Community Interest Company: a Social Enterprise Organisation
Logo above: PHAST: 'Public Health Action Support Team'
Eye care in the UK: Epidemiology, intervention and Ethnicity
Kieran O’Donnell
PHAST
August 2009
Cover image: distorted image representing central vision loss
due to age-related macular degeneration from Bressler (2002)
Public Health Action Support Team CIC
A Social Enterprise organisation and Community Interest Company
Registered office: PO Box 1295, 20 Station Road, Gerrards Cross, Buckinghamshire, SL9 8EL
English Company Number: 06480440
VAT Registration: 926 9466 78
www.phast.org.uk
E&OE
Literature Review
P187 Care Needs Assessment:
Eye Health
This Literature Review was produced as part of a wider Eye Care
Needs Assessment for NHS Tower Hamlets, carried out by a team
supplied by the Public Health Action Support Team CIC (PHAST).
PHAST is a community interest company providing high quality,
evidence based, innovative, rapid results in public health projects,
commissioning, consultancy, training and interim staff.
For this project the team consisted of:
Peter Gluckman
Isabelle Iny
David Lawrence
Les Mayhew
Kieran O’Donnell
Margaret Simons
For further information please see www.phast.org.uk
Disclaimer
This literature review was produced by PHAST for NHS Tower
Hamlets in September 2009 as part of the ‘Care Needs Assessment:
Eye Health’ project commissioned by NHS Tower Hamlets. All
information provided in this literature review was correct at the time of
production and was produced for the sole purpose of supporting the
above commissioned project. PHAST shall not be liable in any way
whatsoever for any use of the material for any purpose other than that
for which the same was originally prepared or intended.
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CONTENTS
INTRODUCTION: _______________________________________ 4
METHOD: _____________________________________________ 5
RESULTS: ____________________________________________ 6
AGE RELATED MACULAR DEGENERATION (AMD) _________________ 6
Pathology: __________________________________________ 6
Epidemiology _______________________________________ 7
Risk factors: ________________________________________ 7
Treatments ________________________________________ 10
CATARACT ___________________________________________ 12
Pathology _________________________________________ 13
Epidemiology: ______________________________________ 13
Risk factors: _______________________________________ 14
Cost effectiveness: __________________________________ 15
DIABETIC RETINOPATHY: _________________________________ 15
Pathology: _________________________________________ 16
Epidemiology: ______________________________________ 17
Risk factors: _______________________________________ 18
Treatment:_________________________________________ 20
Screening: _________________________________________ 23
GLAUCOMA: __________________________________________ 24
Pathology _________________________________________ 24
Epidemiology: ______________________________________ 25
Risk factors: _______________________________________ 26
Modifiable risk factors: _______________________________ 27
Treatments: ________________________________________ 28
Cost effectiveness: __________________________________ 29
Screening: _________________________________________ 30
LOW VISION SERVICES: __________________________________ 31
MINORITY GROUPS AND THE SOUTH ASIAN COMMUNITY: __________ 33
The South Asian community: __________________________ 33
Groups with learning difficulties/disabilities: _______________ 36
SUMMARY: __________________________________________ 37
REFERENCES: _______________________________________ 40
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Introduction:
Eye health is a crucial determinant of quality of life. Those with
a visual impairment or blindness are more likely to be of low
socioeconomic status, be unemployed and have poor health (Nazroo,
2009), although visual impairment affects all ethnic and social groups.
In 2008 there are approximately 153,000 people registered as
severely sight impaired (previously “blind”) and 156,000 registered as
sight impaired (or “partly sighted”) across the UK (NHS information
Centre, 2009). The Royal National Institute for Blind people (RNIB)
suggest this figure is an underestimate and the ‘true’ figure may be
closer to 1,000,000, with a further 1,000,000 living with visual
impairment of some kind (Keil, 2008) .
The cost of visual impairment in the UK is substantial with the
direct medical cost estimated at £2.14billion in 2008 (Access
Economics, 2009). When the indirect cost to society and the
individual are estimated, the total cost approximates £22billion
(Access Economics, 2009). The five most common forms of visual
impairment which can result in loss of vision are; refractive error,
cataract, age-related macular degeneration (AMD), Diabetic
retinopathy and Glaucoma. Many of these conditions show age and
ethnic biases. A recent study reported 1 in 8 people over 75 and 1 in
3 people over 90 years have a significant sight loss (Evans et al.,
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2004). Such findings are noteworthy given the ageing and ethnically
diverse population of the UK.
This review article is intended to provide a description of the
four main causes of visual impairment in the UK in terms of its clinical
appearance and epidemiology. Successful interventions and
treatments will be reviewed together with any available data on cost
analysis or effectiveness. Finally the needs of special groups will be
addressed. This section will focus on the Bangladeshi and south
Asian communities which constitute a significant portion of the
population of Tower Hamlets.
Method:
A detailed literature search was carried out in Pubmed, the
Cochrane Review Database and the NHS evidence website using the
search terms ‘Eye care/health’, ‘UK’, ‘Models of care’, ‘service
delivery’, ‘age-related macular degeneration’, ‘Cataract’, ‘Diabetic
retinopathy’, ‘Bangladeshi’ and ‘South Asian’. Additional references
were sourced from the bibliographies of relevant papers. A more
general internet search was used to source documents related to
Tower Hamlets and visual impairment in the UK. These documents
and the relevant links are provided below (see reference section).
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Results:
Age related macular Degeneration (AMD)
Figure 1: Age-related macular degeneration: These retinal scan
images depict different stages of AMD. The first demonstrates
intermediate AMD yellow deposits are visible across the retina. The
middle images shows loss of retinal pigment and evidence of newly
formed blood vessel. The final image shows Late AMD with retinal
haemorrhage.
Pathology:
Age related macular degeneration (AMD) refers to the
breakdown of retinal membranes. Early AMD may be associated with
increased number of fatty deposits of a material called drusen around
the macula, a heavily pigmented area of the retina.
Vision loss due to AMD is more associated with the late forms
of AMD of which there are two types. The first is known as dry
(geographic/atrophic) AMD. This is occurs due to the thinning of the
macula and results in blurring of vision. This process may be
followed by the formation of new blood vessels which are weak and
susceptible to haemorrhage. This so called ‘wet’ AMD can result in
severe loss of central vision (see cover image). As these processes
are gradual and generally painless early detection can be difficult.
AMD is an incurable condition. There are currently no effective
treatments for dry AMD. Treatments for wet AMD focus on
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preservation of the retina by targeting new blood vessel formation.
Therapies range from intra-ocular injections to laser treatments.
Individuals suffering from AMD are good candidates for low vision
services to best utilise residual vision.
Epidemiology
Age related macular degeneration (AMD) is the most common
form of visual impairment in adults over the age of 55 living in
developed countries (Coleman et al., 2008). By 2020 it is estimated
there will be 8 million affected by AMD worldwide (Bressler, 2002). In
the UK AMD accounts for 42% of blindness in individuals aged 65-75
(Bunce and Wormald, 2008). This figure increases dramatically with
age such that AMD accounts for 75% of blindness in those aged 85
and above (Bunce and Wormald, 2008). Similarly a large scale MRC
study reported AMD to be the most common cause of visual
impairment in individuals aged 75 and over (Evans et al., 2004).
By 2011 one study estimates 250,000 individuals will be living
with a visual impairment in the UK due to AMD (Owen et al., 2003).
This is in line with projections from a recent RNIB report which
estimates approximately 223,000 people will be affected by 2010.
This report goes further by estimating a total of 1,493,963 people
experiencing either early or late AMD by 2010 (Access Economics,
2009).
Risk factors:
The most important risk factor for developing AMD is age. The
prevalence of AMD increases dramatically with age (Coleman et al.,
2008). Pooled data from three large scale population studies (1
American, 1 European and 1 Australian) estimate the prevalence of
AMD to be 0.2% in those aged 55-64 years, rising to 13% in those
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aged 85 years and over (Smith et al., 2001). Another study reports
that AMD was approximately 11 times more common in those aged
75-85 than those aged 45-54 (Klein et al., 2006).
Ethnicity is an important factor in development of AMD. Unlike
many of the other eye conditions described below, white populations
are more susceptible to AMD, followed closely by Chinese people
(Klein et al., 2006). This is of relevance to Tower Hamlets given its
predominantly white older population.
Gender has been shown to have some association with AMD,
notably female sex. This finding from Smith et al (2001) was not very
robust (Smith et al., 2001).
There is a substantial genetic component to AMD with
estimates ranging from 25-75% (Klaver et al., 1998, RNIB, 2009).
Importantly in their study of AMD patients and their families Klaver
and colleagues demonstrated a 5-fold increased risk of AMD in 1st
degree relatives (Klaver et al., 1998). Such findings could be used to
inform policy by adopting a ‘family-centred’ approach to interventions.
A number of modifiable risk factors are also associated with
AMD. A recent meta-analysis using 5 prospective cohort studies and
eight case-controlled studies report a positive association between
smoking and AMD. This association was stronger for current
smoking status, perhaps suggestion of a beneficial effect of smoking
cessation (Cong et al., 2008). This unlike those risk factors listed
above is a potential candidate for intervention strategies.
Alcohol intake is also associated with the deployment of AMD.
In their systematic review Chong and Colleagues (2008) report heavy
drinking (3 or more standard drinks per day) is associated with
developing early AMD. Despite a large sample size the data did not
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permit the relationship between moderate drinking and AMD to be
explored (Chong et al., 2008). The association between heavy
drinking and late AMD was less strong but in three out of the four
studies reviewed the association was positive. The authors suggest
that heavy alcohol intake may reduce the levels of antioxidants which
may promote the development of AMD.
Diet may also be a determinant of eye health. Diets rich in
antioxidants have been found to be protective against developing
AMD (van Leeuwen et al., 2005). In their large population study of
over 5,000 individuals above average consumption of 4 nutrients
(beta carotene, vitamin C, vitamin E, and zinc) was associated with a
35% reduced risk AMD. This result remained significant when
supplement users were excluded suggesting normal dietary intake is
important. A similar finding was reported by the Age Related Eye
Disease Study (AREDS) who found antioxidant supplementation
reduced the incidence of AMD by 25% over a 5 year study period
(AREDS, 2001).
However a recent Cochrane review found no effect of vitamin or
antioxidant supplementation on the development of early or late AMD
(Evans and Henshaw, 2008). An additional systematic review by the
same author suggests a modest benefit of antioxidant
supplementation for slowing the progression of AMD (Evans, 2006).
The authors suggest that such effects may be sensitive to the
population studied. An emphasis is also drawn to the
contraindications of antioxidants in smokers where a link has been
established with the development of lung cancer (Evans, 2006). In
summary antioxidants do appear to be a promising therapeutic agent
and may slow the progression of AMD. The current research would
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suggest increasing dietary intake may be beneficial. Promoting high
dose supplementation of antioxidants should be avoided until more
long term population studies have been completed.
There have been conflicting reports of an association between
AMD and traditional cardiovascular risk factors (reviewed by
Coleman, 2006). Most consistently AMD has been linked to
hypertension, while a protective effect of HDL (good) Cholesterol on
AMD development has been reported in 2 studies (Hyman et al.,
2000, Tomany et al., 2004).
Due to the association found in some studies between
traditional cardiovascular risk factors and AMD, statins are now being
used as a potential therapeutic tool. In a recent Cochrane review
only one randomised control trial was identified as eligible for review.
This trial which included 30 participants showed no effect of
treatment, relative to placebo, at follow up 30-45 days post treatment.
Another trial which is on-going has not shown a beneficial effect at a
12 month follow up assessment. The authors conclude that these
data are insufficient to assess the role of statins in the development of
AMD (Gehlbach et al., 2009)
Treatments
Pharmacological treatments for AMD centre on growth factor
inhibitors to reduce the growth of new blood vessels in the retina. A
number of trials have shown a beneficial effect of Vascular
Endothelial Growth Factors (VEGF) inhibitors. One trial involving
1,200 patients found all subtypes of AMD benefited from treatment
over a two year period (Gragoudas et al., 2004). Similarly a recent
trial of ranibizumab found significantly less functional decline in the
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treatment group, an effect still evident at 24 months follow up
(Rosenfeld et al., 2006).
A cost effectiveness study has been reported for pegatanib
(Mecugen) and has shown cost-effective across all age-groups
studies. Discontinuing treatment in those patients whose vision
deteriorated maximised the cost effectiveness (Wolowacz et al.,
2007). A second cost-effectiveness study again demonstrates the
beneficial effects of a growth factor inhibitor verteporfin (Visudyne).
Using a health economic model the authors demonstrate costeffectiveness to be approximately £20,996 per quality adjusted life
year (Bansback et al., 2006).
An interesting association has been observed between the
progression of AMD and cataract surgery. A number of studies
suggest the successful treatment of cataracts can increase the risk of
developing AMD (Bockelbrink et al., 2008). Bockelbrink et al., 2008
carried out a systematic review of over 2,769 publications. The
authors provide some evidence of a reduced latency to AMD in
patients treated for cataracts. While cataract surgery is now seen as
routine practice, treatments for AMD are often more lengthy, requiring
multiple treatments and follow ups. This association may underscore
the importance of preventative strategies for AMD to ensure the gains
made by cataract surgery uptake are not lost to increased prevalence
of AMD.
Currently surgical interventions are used as a treatment in late
AMD. One on-going RCT is comparing the clinical and costeffectiveness of two different surgical techniques. No data are
available as yet (Lois et al., 2008)
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As stated individuals experiencing visual impairment due to
AMD are good candidates for low vision rehabilitation. This consists
of training and education together with the provision of aids to
maximise an individual’s residual vision (see low vision services
below).
Finally the psychological impact of and AMD diagnosis should
not be overlooked. Mitchell and Bradley (2006) report a two-fold
increased incidence of depression in AMD patients relative to other
community dwelling adults (Mitchell and Bradley, 2006).
Cataract
Figure 2: Older woman with bilateral cataracts. Right eye: advanced
cataract (pupil is densely white). Left eye: early cataract (pupil is
central, round and faintly grey or white in colour).
Photographer: Murray McGavin with permission from International
Centre for Eye Health)
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Pathology
Cataracts are cloudy formations which occur in the lens of the
eye (See figure 2). This occurs through break down of the proteins
found in the lens and a loss of moisture from the lens. Visual
impairment may increases as the size of the cataract grows or cause
blurring of the vision or problems with colour vision. If left untreated
cataracts can result in sight loss. Treatment options include surgical
intervention to remove the affected lens and replace with a substitute
lens. The cost/benefit of this procedure is described as one of the
most effective interventions in healthcare (Riaz et al., 2006).
There are four main types of cataracts 1) age-related, 2)
congenital, 3) Secondary often caused by inflammation or chronic
steroid and 4) traumatic. Of these subtypes age-related cataract is
the most common with increasing prevalence from 60 years onwards.
There is some evidence of a gender bias with females reportedly at a
greater risk than males.
Epidemiology:
Worldwide cataract problems are the leading cause of visual
impairment (WHO, 2005). A study in North London previously
reported the prevalence of vision impairing cataract was 30%.
Worryingly 88% of those with cataract were not under the care of an
eye specialist. Conversely the authors found 72% of the visual
impairments observed were remediable through intervention (Reidy et
al., 1998). The large scale MRC study already cited (Evans et al.,
2004) report cataract as the second greatest cause of visual
impairment observed in 35.9% of cases.
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Risk factors:
Tan et al (2008) in a large epidemiological sample
demonstrated that diabetes and hypertension are associated with an
increased risk of developing cataract (Tan et al., 2008). There is
some limited evidence the smoking is also a risk factor. Finally some
reports suggest women are more likely to develop cataracts however
this may reflect inequalities in access to treatments rather than a
patho-physiological process. Cataract prevention is not viable given
current understanding of the condition. Identifying the most clinically
and cost effective surgical technique, together with improving access
and uptake appear the most realistic therapeutic options at the
current time.
As with AMD, age is a major risk factor for cataract.
Dhaliwal and Gupta (2007) explored the barriers to uptake of
cataract surgery in a Hindi speaking Indian sample. Interestingly,
attitudinal barriers were reported more commonly than those related
to cost (Dhaliwal and Gupta, 2007). Still retaining some functional
ability, not knowing someone who had had surgery, fear of surgery
and religious beliefs were all reported as reasons for reduced uptake.
This would suggest that for any targeted intervention to succeed it
should not only address issues of accessibility but also acceptability.
A recent study carried out in Birmingham suggests that while positive
attitudes towards health exist, eye health is not central to individuals’
perception of general health (Cross et al., 2007). This study focusing
an Afro-Caribbean sample demonstrated poor uptake of glaucoma
information and consultations were generally symptom driven.
An interesting retrospective study has recently suggested that
cataract surgery is associated with overall decreased mortality
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(Blundell et al., 2009). This contrasts with previous research
reporting a greater rate of mortality in those treated for cataracts. The
authors suggest that improvements to the surgical method could
underpin this association (Blundell et al., 2009).
Cost effectiveness:
Given that surgical intervention is seen as a cost effective
strategy for the treatment of cataract studies of cost effectiveness
have tended to focus on the cost/benefit of different types of surgeries
(Riaz et al., 2006) or service provision (Fedorowicz et al., 2005;
Fedorowicz et al., 2006) .
Riaz et al (2006) compared a number of techniques for the
removal of age related cataract. They conclude that
phacoemulsification gave a better visual outcome than extracapsular
surgery with little difference in the cost of the procedure (Riaz et al.,
2006)
Fedorowicz and Lawrence (2005, 2006) compare day case
versus in-patient treatment for cataract. The authors demonstrate
that day case surgery, for the removal of cataract, was both cost
effective and did not result in increased complications (Fedorowicz et
al., 2005; Fedorowicz et al., 2006)
Diabetic retinopathy:
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Figure 3: Vision loss due to diabetic retinopathy. The image on the right
represents how an individual may view the scene on the left (available
from http://www.nei.nih.gov/health/diabetic/retinopathy.asp)
Pathology:
Diabetic retinopathy is the most common cause of blindness in
working age people in the UK (Bunce and Wormald, 2008). The
disease has a rapid progression and occurs in both early and late
onset diabetes. If left untreated, of those progressing to the late
stages of the disease 50% will be blind within 2 years (Hamilton et al.,
1996).
The disease can be classified into 4 stages:
1)
Mild non-proliferative retinopathy. This stage is
characterized by swelling (microaneurysms) within the
blood vessels of the retina.
2)
Moderate non-proliferative retinopathy. Some blood
vessels that nourish the retina become blocked
3)
Severe non-proliferative retinopathy. Several areas of
the retina become deprived of adequate blood supply
4)
Proliferative retinopathy. New blood vessels grow to
compensate for the lack of blood supply. These vessels
are weak hemorrhaging easily which results in visual
impairment.
Source: National Eye Institute: http://www.nei.nih.gov/health/diabetic/retinopathy.asp
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Throughout these stages fluid may leak into the retinal
membranes particularly the macula, causing swelling (macular
oedema). This can impair central vision.
Diabetic retinopathy often has no symptoms. As the condition
progresses patients may become aware of blurring or specks in the
visual field. Diagnosis of Diabetic retinopathy may be made by eye
chart tests or imaging the retina.
Early detection of the condition and laser treatment can halve the risk
of sight loss. In 2007 screening was offered to 85.7% of newly
diagnosed diabetic patients. While this met national guidelines the
Department of Health has set a more ambitious target of 100%
screening of those diagnosed with diabetes (see screening section
below) (Department of health, 2008).
Epidemiology:
The prevalence of diabetic retinopathy is inevitably linked to the
incidence of diabetes. Worldwide diabetes is increasing with
projections estimating a worldwide diabetic population of 300million
by 2025 (King et al., 1998). This can be seen at a local level with the
diabetic population of Tower Hamlets projected to grow to 16, 000 by
2026, a doubling of the level seen in 2001 (See figure 4) (Healthcare
for London, 2008). These data underscore the importance of
developing effective strategies to tackle the increasing rates of
diabetic retinopathy which will track the increased rates of diabetes in
Tower Hamlets.
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Figure 4: The prevalence of diabetes in Tower Hamlets PCT 2001 to
2026 (from Healthcare for London, 2008)
Risk factors:
There is evidence to suggest diabetic retinopathy is more
common in type 1 diabetic patients. However a common risk factor
for both subtypes relates to duration of disease. Changes to the
retina may be observed in diabetic patients at diagnosis, however a
greater duration of disease is related to an increased risk of
developing retinopathy. This was clearly demonstrated by Klein and
colleagues who report the prevalence of diabetic retinopathy in type 1
and type 2 patients grouped by the duration of disease (5 years
versus 15 years). For type 1 patients’ diabetic retinopathy was seen
in 17% (5 years or less) to 98% (15years or more) of individuals. In
type 2 patients the prevalence of retinopathy was found to be 29%
and 78% of patients with a disease duration of 5 and 15 years
respectively (Klein, 2007). This has been replicated in a number of
epidemiological studies (see Klein, 2007). The strength of this
association is such that most diabetics will experience retinopathy if
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they live long enough (Williams et al., 2004; Klein, 2007). Such data
highlight the clear need to address disease management and reduce
secondary complications such as retinopathy.
Two studies based in London demonstrate the higher
prevalence of diabetes and diabetes related complications in the
South Asian community (Mather, 1985, Nicholl et al., 1986). South
Asians, resident in Southall, were 4 times more likely to develop
diabetes (Mather, 1984). Furthermore this group found that despite a
shorter duration and younger age, Asian diabetic patients were more
likely to report secondary complications including increased rates of
retinopathy (Nicholl et al 1986).
A more recent study carried out in Bradford compared the rates
of diabetic retinopathy in South Asians versus a sample of
Caucasians. Higher rates of retinopathy were reported for all age
ranges in South Asians relative to Caucasians (Figure 5) (Pardhan et
al.). From their data the authors find that the rates of retinopathy
shown in Caucasians occur approximately 12 years earlier in their
South Asian sample (Pardhan et al.). This finding contrasts with
another study which found a lower prevalence of retinopathy in
Asians versus Caucasians suggesting the other characteristics of the
population may also be important (Samanta et al., 1991). However a
recent publication from the RNIB suggests approximately 35%
increased risk of visual impairment in Asian versus white people from
the UK due to diabetic disease (Access Economics, 2009). This
figure is based on a complex model using data from multiple sources
including (but not limited to) household census and academic
publications e.g. Evans et al (2002, 2004) Reidy et al (1998).
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Figure 5: Rates of diabetic retinopathy in Asian versus Caucasian
patients. Age groups range from 45-80 years and over. From
Pardhan et al (2004).
Such findings, particularly those of Pardhan et al (2004) may be
of importance to service provision in Tower Hamlets. This study
suggests that any existing interventions should be focused at an
earlier age in the South Asian community.
Additional risk factors for diabetic retinopathy include
hypertension, elevated blood/sugar, pregnancy and renal disease.
While smoking, obesity and physical inactivity have shown some
association with diabetic retinopathy.
Treatment:
Mohamed et al., (2007) performed a systematic review
encompassing 44 studies (including 3 meta-analyses) and describes
the current management of diabetic retinopathy (Mohamed et al.,
2007).
Controlling a patient’s blood/sugar level has been demonstrated
to be an effective treatment strategy for preventing and delaying the
progression of diabetic retinopathy (Klein, 1996). Such strategies can
have a dramatic impact on the incidence and progression of diabetic
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retinopathy with glycaemic control associated with a 76% and 54%
reduction in the incidence and progression of diabetic retinopathy
respectively (see Mohamed et al., 2007). This strategy together with
blood pressure control remains the only proven effective primary
intervention for diabetic retinopathy (Mohamed et al., 2007).
An effective medical intervention to prevent the onset or
progression of diabetic retinopathy remains elusive. A series of
promising agents have had disappointing results in clinical trials
(Mohamed et al., 2007). A recent example comes from the
CALDIRET study (Haritoglou et al., 2009). This clinical trial found no
effect of calcium dobesilate in the incidence of macular oedema
(symptom associated with diabetic retinopathy) over the five year
study period (Haritoglou et al., 2009).
Fenofibrate, a drug treatment for blood lipid control has also
received some modest success (Mohamed et al., 2007). An
intervention study demonstrated a reduced rate of retinal laser
surgery in those receiving treatment (Keech et al., 2005). While the
results from the fenofibrate study are encouraging replication in other
populations is required. This is highlighted by more recent data from
the same study showing the benefits gained from fenofibrate
treatment were independent of blood lipid or blood glucose level,
suggesting another mechanism of action for fenofibrate (Keech et al.,
2007).
A recent study has demonstrated an effect of candesartan, a
drug which strengthens the blood vessels and may prevent
haemorrhaging in the eye (Sjølie, 2008). This study showed the drug
reduced the incidence of retinopathy in type 1 diabetics but the
effects in type 2 diabetics failed to reach significance. Additionally the
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benefits observed were seen in patients in the early stages of the
disease highlighting the importance of early screening (Sjølie, 2008).
Secondary interventions for diabetic retinopathy include laser
and surgical interventions. The strongest benefit from these
interventions is seen in those with proliferative diabetic retinopathy.
In earlier stages of the disease the benefits of laser surgery can be
off-set by the complications e.g. loss of colour or night vision
(Mohamed et al., 2007).
Other treatments for diabetic retinopathy include corticosteroids
and anti-growth factors. Corticosteroids have been shown to improve
vision over a 2 year period however this improvement was also
associated with an increased rate of cataract in the treatment group.
VEGF inhibitors as described in the treatment of AMD may have a
role in the treatment of diabetic retinopathy. Both of these conditions
benefit from management of new blood vessel formation. Pegaptanib
has been shown to improve vision following treatment and reduced
the need for laser surgery in the treatment group (Cunningham et al.,
2005). However these findings were based on a short study
timeframe and detailed longitudinal study of such agents in the
treatment of diabetic retinopathy is required (Mohamed et al., 2007).
In summary, of the treatment options available blood/sugar and
blood pressure regulation appear the most consistently replicated
effective strategies for preventing or delaying diabetic retinopathy.
An encouraging recent finding comes from a longitudinal study
of diabetic retinopathy (Klein et al.). Klein and colleagues found
evidence to suggest that strategies to reduce diabetic retinopathy and
resultant loss of vision could prove effective. Controlling for duration
of diabetes, blood sugar and a range of other factors those with a
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more recent diagnosis were almost 10% less likely to suffer from
diabetic retinopathy (Klein et al., 2009). The authors suggest this
indicates that at least for early on-set diabetes successful
management and preventative strategies (e.g. photocoagulation
therapy) can be beneficial.
Screening:
From a recent diabetes strategy report by Tower Hamlets PCT
it is clear that this screening target has not been achieved (Tower
Hamlets PCT, 2009). The report reports that between 30-40% of
patients invited for retinal screening fail to attend. This combined with
data from the London health observatory indicating only 72.35% of
patients are offered a retinal screen implies a screening level of
between 33-43%. It is clear that the problem is multi-factorial.
Improved record keeping should help increase the number offered
retinal screening. However this must occur in parallel with attempts
to increase uptake of screening. Given the results of Dhaliwal and
Gupta (2007) and related literature it seems vital that community,
cultural and contextual factors be will be integrated into any screening
program.
A key aim of the National Screening Committee is to reduce the
incidence of blindness occurring due to diabetic retinopathy within 5
years (James et al., 2000).
James and Colleagues provide a detailed cost analysis
comparing opportunistic versus systematic screening for diabetic
retinopathy. They conclude that the cost/benefit of replacing
opportunistic methods with more systematic screening protocols is
justified yielding an additional 157 cases at £32 extra per case
(James et al., 2000).
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A special group for consideration in relation to screening is
young children and adolescents. There is emerging evidence that
diabetic retinopathy can precede other symptoms of diabetes. A
series of studies, mainly from Japan, have documented both
background and progressive retinopathy in participants ranging in
ages from 17-28 (see Pinhas-Hamiel and Zeitler, 2007). Such
findings are important both in the context of increasing rates of
diabetes in young people (Pinhas-Hamiel and Zeitler, 2007) but also
given the evidence to suggest retinopathy occurs earlier in ethnic
minorities than Caucasians (Pardhan et al.). If these findings are
supported by research in South Asian samples it may strengthen the
case for screening in adolescence.
Glaucoma:
Pathology
Glaucoma is often referred to as the ‘Sneak thief of sight’ or the
‘Silent Blinder’. This is because the glaucoma is the most common
form of irreversible blindness, characterised by an insidious onset
leading to permanent nerve damage and blindness.
There are a number of glaucomas however two main categories
may be used to distinguish different aspects of the condition 1)
primary open angle glaucoma (POAG) and 2) primary closed angle
glaucoma (PCAG). The first and most common is a chronic condition
and difficult to detect. One study reports 50% of people with
glaucoma are unaware of its presence (Tielsch et al., 1991).
Conversely PCAG is much less common but more acute and can
cause severe and rapid loss of vision. In PCAG the Iris obstructs the
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set, cause pain, headaches and nausea. If untreated, PCAG can
result in permanent sight loss over a short period. In POAG the Iris
does not obstruct the outflow from the eye (open angle) however
progression of the condition will result in loss of vision.
In the past increased intra-ocular pressure (IOP) or pressure
within the eye was viewed as a defining feature of glaucoma, with
IOP greater than 21mm Hg characteristic of the condition (Coleman,
1999). However the modern clinical definition focuses more on the
extent of visual field loss and changes in the optic nerve head
(Coleman, 1999). Such symptoms can, but do not always, result in
higher IOP. Despite this change of definition of POAG the focus of
current treatments revolve around reducing IOP to protect the nerve
fibres in the eye from further damage. This is seen as the only
proven and treatable risk factor (Weinreb and Khaw, 2004)
Unlike AMD glaucoma tend to result in loss of peripheral vision
and depth perception. This can result in a higher rate of falls and car
accidents in these patients and have a detrimental effect on an
individual’s quality of life (Coleman, 1999).
Epidemiology:
The number of people affected by POAG (the most common
form) is around 1.33% of the population (Quigley and Vitale, 1997).
There is an association with increasing age with the prevalence of
glaucoma reported as 3% in a North London cohort aged 65 and over
(Reidy et al., 1998). A recent study found glaucoma was the cause of
nearly 11% of blind registrations in the UK (Bunce and Wormald,
2008). However it should be noted that prevalence data is population
sensitive as certain ethnicities are at a greater risk of developing the
condition (see below).
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Risk factors:
Glaucoma shows increased prevalence in certain ethnicities.
Eskimo, Chinese, Afro-Caribbean and South Asian samples have
been shown to have greatly increased risk. In terms of ethnicity the
Afro-Caribbean community are at greatest risk of developing POAG.
This group are 8 times more likely to develop POAG which usually
has an earlier onset in this ethnic group (Cross et al., 2007). Asian
populations (including South Asian) are another high risk group.
A large population study in India (age 30 years and over)
reports POAG as a cause of blindness in 12.1% of a visually impaired
sample, a figure similar to that seen in the UK (Dandona et al., 1998;
Bunce and Wormald, 2008). The prevalence rate of POAG is
reported as 3.2% in a South Indian sample aged 45 years and over
(Vijaya et al., 2008b). There is a significant effect of age with the
prevalence of POAG rising from 2.25% (40-49 years) to 10.2% (80
years and over) (Vijaya et al., 2008b). Two studies have focused
specifically on samples from Bangladesh.
The prevalence of POAG was consistent between both studies
at 3.4% (Raychaudhuri et al., 2005) and 3.1% (Rahman et al., 2004)
in those aged 40 years and over. These figures demonstrate almost
a 2-fold increased prevalence of POAG in Bangladeshi samples
relative those reported from a large sample of white Americans
(1.69%) (Friedman et al., 2004).
Similarly the prevalence of PCAG is seen to be higher in South
Indian samples relative to UK samples. A recent study reported
approximately 9 cases of PCAG per 1000 screened in a South Indian
sample (Vijaya et al., 2008a). This is in marked contrast to a recent
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UK based study which reported approximately 4 cases per 100,000
screenings (Keenan et al., 2009).
The prevalence findings reported in the studies above are of
importance when considering the ethnic profile of Tower Hamlets.
Despite the overall low prevalence of glaucoma in the UK, in Tower
Hamlets, an area enriched with high-risk ethnicities, glaucoma
awareness should be a priority.
Similar to AMD there is a strong genetic link to glaucoma. At
least 6 genes have been identified which increase the risk of
developing glaucoma (Coleman, 1999). Unsurprisingly this gives rise
to elevated risk in families with an affected member. A study in the
US suggested the risk was trebled in first degree relatives, while a
European study found the risk rose to nine times that of non-relatives.
These findings strengthen the idea that awareness of glaucoma
should have a family focus. Effective campaigns highlighting the
heritability of glaucoma may prove most cost effective.
Modifiable risk factors:
The most consistent risk factor both for the development and
progression of POAG is increased IOP (Coleman and Miglior, 2008).
Individuals with a higher than average IOP at baseline, were 10-14%
more likely to go on to develop POAG over the course of 5-9 years
(Coleman and Miglior, 2008). The authors of this study report that
increased IOP and age are the two most prominent risk factors for
developing POAG. As discussed below a reduction in IOP may be
achieved by medication or surgical intervention. These treatments
will be described briefly together with an evaluation of their
cost/benefit.
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Treatments:
The initial treatment of POAG usually centres on topical or oral
medication to lower the IOP. These pharmacological agents reduce
IOP either through decreased production or increased clearance of
aqueous humor (see Table 1) (Weinreb and Khaw, 2004). These
medications are not without side-effects a factor which should be
considered when assessing the cost effectiveness of these
treatments (Anderson et al., 2009).
Table 1: Medical treatments for POAG their action and side effects.
From Coleman (1999)
Laser surgery may be used to increase the drainage of fluid
from the eye (laser trabeculoplasty). This procedure while initially
effective has been shown to have a failure rate of about 10% per year
such that by 5 years there is a 50% failure rate (Weinreb and Khaw,
2004). A second laser treatment (laser diode cyclophotocoagulation)
is used in advanced POAG targets aqueous humor production. This
procedure tends to have limited and transitory beneficial effects
(Weinreb and Khaw, 2004).
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Conventional surgical interventions may also be considered for
the treatment of POAG. By removing a portion of the ineffective
drainage network (Trabeculectomy) outflow may be enhanced. This
procedure has been found to reduce IOP and preserve vision but due
to its invasive nature and risk of complications is no longer used as a
primary intervention (Weinreb and Khaw, 2004).
The concept of neuroprotection and glaucoma has received
attention in recent years. There are a number of therapeutic agents
which can protect and preserve the nerves of the eye, termed
neuroprotectants (McKinnon et al., 2008). These agents in
combination with attempts to reduce IOP may prove beneficial in the
treatment of glaucoma, although data from well controlled trials are
lacking.
The treatment for PCAG primarily focuses on removing the
obstruction to the drainage system of the eye. Medical treatments
are similar to those described above for POAG however the mainstay
of PCAG treatment is creating an opening in the peripheral iris (laser
iridotomy) (Coleman, 1999)
Cost effectiveness:
Schmier and colleagues provide a detailed review of studies
reporting cost analyses of the medical treatment of glaucoma
(Schmier et al., 2007). The authors report that many studies focus
only on the cost of medication and fail to factor in the cost to the
individual or society. The authors call for a more standardised
approach to assessing cost effectiveness in the study of glaucoma
such as ‘cost of reaching target IOP’. The authors conclude that
older treatments focusing on the adrenergic system are most costly
relative to newer prostaglandin analogues (Schmier et al., 2007).
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However the systemic side effects of such drugs should also be
factored into any cost analysis (Weinreb and Khaw, 2004). For
example prostaglandins have been shown to induce respiratory
problems in some people (1 in 24). This can result in higher costs
due to these systemic side effects. In summary, while prostaglandin
analogues appear the more cost effective data are required on the
true cost of these treatments factoring in treatment for side-effects.
Screening:
Weinreb and Khaw (2004) suggest a screening protocol for
glaucoma based on ethnicity and age groups. Focusing on AfricanAmericans versus other non-symptomatic patients they propose the
schedule detailed in Table 2 (Weinreb and Khaw, 2004). A schedule
such as detailed in table 2 may well be applicable to other high risk
groups such as the South Asian community.
Age (years)
Asymptomatic
Other
African Americans
Asymptomatic
patients
20–29
Every 3–5 years
At least once
30–39
Every 2–4 years
At least twice
40–64
Every 2–4 years
Every 2–4 years
>65
Every 1–2 years
Every 1–2 years
Table 2: Suggested screening protocol for high and normal risk
asymptomatic patients. Modified from Weinreb and Khaw (2004)
Baker and colleagues (2009) have recently reported good
public knowledge of glaucoma. However the authors report a
significantly lower level of awareness in a London based (Ealing)
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ethnic minority group formed predominantly of Indian minority groups
(Baker et al., 2009). While interesting and suggestive of the disparity
in levels of awareness this study did not address if there was
decreased uptake of eye care services between groups. This study
highlights the need to target ethnic minorities who may be at
increased risk of developing glaucoma.
Low vision services:
Approximately 80% of those with visual impairment have useful
residual vision and may benefit from low vision aids (Bruce, 1991,
Culham et al., 2002)
Culham et al., (2002) report patchy low vision service provision
across the UK. They propose this may be due to a lack of an ideal
model of care for low vision rehabilitation and call for further research.
Given the ageing population of the UK they call for investment in low
vision services and tentatively suggest three appointments to assess
prescribe and follow up those seeking low vision aids (Culham et al.,
2002).
The authors also report approximately 65% of low vision
consultations occur in hospital settings. This is despite adequate
expertise and training in primary care settings. They suggest this
underutilisation of primary care settings should be addressed which
would improve accessibility and may prove more cost effective.
Low vision rehabilitation generally involves reducing visual
impairment disability through the provision of aids such as magnifiers
and teaching patients the importance of controlling illumination. A
recent randomised controlled trial found no additional benefit of home
visits when compared to conventional hospital based low vision
rehabilitation. This study carried out in Manchester with an elderly
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sample (>80 years of age) found no difference in quality of life or
performance on a vision task at 12 months between three arms of the
RCT (Reeves et al., 2004). Such findings underscore the importance
of trialling services to ensure interventions are effective before
widespread implementation.
An interesting model of care has been implemented in South
Devon which has shown good levels of patient satisfaction and
compliance. This multi-disciplinary multi-agency team involves
partnership with local enterprise, the RNIB and non-social services
(Collins and Skilton, 2004). To date data is only available on
satisfaction and compliance but with an average referral to
completion of three weeks it appears a useful model. In addition to
the practical advice and information about low vision aids a counsellor
is available to address the psychological aspects of living with a
visual impairment.
A study which focused on reduced uptake of low vision services
demonstrated the importance of cultural sensitivity and the availability
of non-English materials. O’Connor et al found a third of their sample
which failed to complete the referral process were non-English
speaking (O'Connor et al., 2008).
The Low Vision Service Implementation Group (LVSIG) recently
published a national evaluation report for UK based Low vision
services (Gibson, Hundt and Stuttaford, 2005). They cite lack of
funding as a barrier to the provision of high class service. They
conclude however that low vision services have improved between
1999 and 2004. The report does not however address if there is a
disparity between the services received by specific minority groups.
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Minority groups and the South Asian Community:
A recent study based in Leeds makes a number of
recommendations to engage the South Asian community in clinical
trials. Many of these recommendations may also be applicable to eye
care service delivery (Hussain-Gambles et al., 2004). The authors
report social class was a greater determinant than ethnicity per se.
Other barriers to participation included religion, gender issues and
community gossip. The recommendations include engaging the local
community through focus groups and consulting representatives from
the community such as community leaders to raise the profile of
clinical trials within the community. The need for health professionals
to be culturally sensitive was emphasised. Further, by determining the
most appropriate mass media the profile of trials could be augmented
(Hussain-Gambles et al., 2004).
The South Asian community:
A recent study carried out in Tower Hamlets supports many of
the findings of Hussain-Gambles et al (2004) but in the context of
visual impairment and eye care. Despite government guidelines on
promoting inclusion within Tower Hamlets success has been modest
at best (Ahmed, Cheesman and Robin, 2003). Sainsbury and Alam
focus on three minority ethnic groups Bangladeshi, Gujarati and
Somali together with a group of white British blind people. A series of
qualitative interviews were carried out with these subgroups.
Sainsbury and Alam (2006) explore the concept of modern day
racism and how this may impinge on the health seeking behaviours of
ethnic minorities. The authors report participants’ experience of
institutional racism and give examples of how this can influence
perceptions of primary care settings. The authors find overt racism
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may reduce the use of aids such as canes. A participant reported
feeling at increased risk of racism due to his loss of vision and felt a
white cane would increase the likelihood of being targeted. This
highlights the need of commissioners to be aware of the practical
limitations of being labelled disabled in a deprived area.
An interesting observation from this study was that social class
was a greater determinant of the experience of overt racism.
Members of the Gujarati community, many based in North London
were less likely to experience overt racism than their Somali or
Bangladeshi counterparts living in Tower Hamlets.
Another theme emerging from the interviews was the need for a
holistic approach to assessment. The authors also stress the
importance of an individualised approach to service provision. This
theme is in keeping with current governmental policy directives
promoting more person centred approaches to care. An example
was home visits which participants felt would meet their needs more
effectively than services available in the community.
Based on these interviews the authors make 5 recommendations for
policy makers:
1) An individual should be assessed in the context of their family,
community and local environment
2) Monitoring should be on-going and dynamic, sensitive to
changing needs of an individual over time
3) In-service training for social workers may enhance
understanding of local communities
4) Visual impairment specialists should not only be knowledgeable
about visual impairment but appreciate the value of family and
community
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5) User perspective should form a element of training for
specialists
This study describes challenges faced by a group of ethnic
minorities in Tower Hamlets. The authors acknowledge that sampling
was not random and may be biased in favour of men. Additionally,
demographic information such as socioeconomic status or education
attainment is not reported. Participants ranged in age from young
adults to elderly. It may be difficult to generalise these findings to the
experience of all South Asians in Tower Hamlets. However the
interviews underscore the complexity of service provision for such
minority groups. A clear and achievable starting point to address
issues of social inclusion is more detailed ethnic monitoring of service
uptake.
Despite this complexity targeting minority groups could provide
cost effective and result in overall decreased long term health care
expenditure. In a recent RNIB report a series of 4 scenarios based
on eye care intervention were explored. The scenario targeting the
needs of minorities groups showed the greatest cost effectiveness
ratio. Explanations for this increased cost efficiency centre on
minority’s reduced access to care and resultant greater severity of
eye conditions (Access Economics, 2009).
An interesting recent study has shown that ethnic minorities in
the UK (including Bangladeshi community members) were not less
likely to access primary care for cardiovascular and diabetes related
care. Differences did emerge in terms of hospital based services and
dental treatment. This perhaps underscores the importance of
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community based practices for eye care service delivery (Nazroo et
al., 2009).
A recent Thomas Polkington report makes a number of best
practice suggestions for commissioners (Joule and Levenson, 2008).
These focus on a holistic approach to assessment of the individual,
similar to that advocated by Sainsbury and Alam (2006). These
recommendations go further by also placing an emphasis on carers.
Of particular relevance to Tower Hamlets the authors highlight the
work of SeeAbility and Dekhtay Chai. The work of SeeAbility is
acknowledged and the authors emphasise the importance of such
outreach work to engage visually impaired individuals from minority
backgrounds.
Dekhtay Chai is a voluntary organisation which provides
information and support for minority groups particularly those from the
Bengali and Bangladeshi communities. The authors report that
Dekhtay Chai through providing information on benefits and
entitlements has increased the uptake of services, however no data
are presented (Joule and Levenson, 2008). From this report it is
clear that there are groups working in Tower Hamlets already
engaging with minority groups. It would seem prudent to build upon
any successes of these groups to increase awareness and uptake of
eye care in Tower Hamlets.
Groups with learning difficulties/disabilities:
Another group of individuals which may require targeted
interventions are those living with intellectual disabilities. People with
learning disabilities are less likely to undergo an eye test. This may
be due to such groups living independently or relying on family
members as informal carers (Starling et al., 2006). Furthermore
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people with learning difficulties may be less likely to notice changes in
their vision. These factors suggest that special attention must be paid
to intellectually disabled groups. The literature in this area has
predominantly focused on individual syndromes such as Down
syndrome. A recent study has shown that a range of conditions were
observed in a sample of children with Down syndrome including
refractive errors and cataracts (Stephen et al., 2007). Other studies
consistently report ophthalmic abnormalities in children with Down
syndrome highlighting the need for early screening for this population
(e.g. Da Cunha and Moreira, 1996).
Of particular interest in this area is the study of Van Istardel
(2007). The authors noted a significant relationship between adults
with a learning disability, visual impairment and mobility. In their
retrospective study those that were not visually impaired showed
increased mobility. Although this study was carried out using an
institutionalised sample the findings may have implications for the
wider community. By protecting vision in vulnerable adults greater
independence may be achieved which could potentially reduce
avoidable burden on carers and healthcare providers.
Summary:
Outlined above are four of the main causes of visual impairment
in the UK. As the population of the UK grows older and more diverse
the prevalence of many of these conditions will increase dramatically.
A number of key points emerge from the literature which may
be useful when formulating interventions.
1) The importance of family: Many of the conditions outlined
above show a strong genetic component. By increasing awareness
of the heritability of conditions such as glaucoma and AMD,
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interventions stand to maximise their benefits. In addition to this the
qualitative studies underscore the central role families can play in the
uptake of eye services. Finally the results from the study focused on
people with intellectual disabilities show they can often be reliant on
family members to facilitate access to services.
2) Age is a major risk factor: AMD, Cataract, glaucoma and to
an extent diabetic retinopathy (i.e. duration of diagnosis) all show a
positive association with age.
3) Ethnicity is a determinant of risk: AMD, glaucoma, diabetic
retinopathy demonstrate marked variation in terms of prevalence.
Further to this ethnicity is also a determinant of uptake of services.
This makes it especially important to ensure access to eye care for
ethnic groups at most risk of developing these conditions.
4) The need for targeted screening and holistic assessment: As
demonstrated by
Smeeth and Illeth (2006) in a systematic review of screening in the
elderly, general screening for visual impairment is unlikely to prove
cost effective (Smeeth and Iliffe, 2006). Rather targeted systematic
screening including known risk factors and standardised assessments
is more likely to prove cost effective and clinically relevant (James et
al., 2000). This point is of particular relevance to Tower Hamlets
when its population is stratified by age and ethnicity. In Tower
Hamlets a series of focused targeted campaigns by age group,
ethnicity or other risk factor may prove more beneficial than a more
generalised approach.
5) Investment should be made in low vision services: while
prevention is a primary objective for many of these conditions,
inevitably some individuals will experience visual impairment. By
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helping these individuals maximise their residual vision it may
improve both the outcome for the individual (e.g. quality of life) and
promote independent living.
The RNIB projections for sight loss in the UK by 2020 suggest
expenditure due to the four conditions outlined above is set to grow
substantially over the next 10 years. By developing cost effective
interventions/strategies perhaps some of this cost can be defrayed
and result in improved service delivery and uptake.
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