My Most Commonly Asked Questions Related to Glaucoma
Murray Fingeret, OD
Murray Fingeret, OD
Clinical Professor, SUNY College of Optometry
Chief, Optometry Section, Dept Veterans Affairs, NYHHCS, Brooklyn, NY
718-298-8498
murray.fingeret@va.gov
This course will discuss the most common questions I receive. Examples are: should IOP
be converted based upon corneal thickness, is there a need to treat if glaucomatous
damage is not present, what should I do for therapy after using prostaglandins. These are
other questions related to both diagnosis and therapy will be addressed.
1. Is the optic nerve the first site of glaucomatous damage?
The structure-function relationship will be explored, illustrating examples where
the optic nerve changes first, followed by selective field loss (SWAP, FDT) and then
loss on standard automated perimetry. Still looking at Ocular Hypertension Treatment
Study (OHTS) data, fields are often the initial way that glaucoma is diagnosed.
2. Is pachymetry a standard of care?
The role of corneal thickness measurements will be discussed and why this test is
crucial to better understand the intraocular pressure (IOP) within the eye. Is role as a
surrogate for risk will be described based upon OHTS data.
3. Do you correct the IOP for corneal thickness?
Clinicians have been besieged with conversion charts, often used by companies
for marketing purposes, and are confused about their importance. The issue that there
is no accepted algorithm will be described. Also, other biomechanical factors such as
corneal rigidity play a role in IOP measurements and why a simple conversion chart
often does not work well.
4. Is a person who has had refractive surgery at a greater risk for developing
glaucoma? This common question relates to the naturally thin cornea offering
greater risk for glaucoma development. A surgically thin cornea does not have
this risk but rather will simply underestimate the IOP.
5. Are risk calculators useful in determining which individuals with ocular
hypertension should be treated?
Risk assessment is becoming a new tool useful to recognize which individuals
with ocular hypertension are at risk of developing glaucoma and deserve therapy.
Risk assessment as a tool will be discussed. Data from OHTS has shown that rather
than 1% of inviduals with OHTN developing glaucoma per year, when we look at
IOP, Cup/Disc ratio, visual fields, age and corneal thickness- the figure for some
increase to 7% conversion per year. It is those individuals in which therapy is
considered.
6. Is Diabetes a risk factor for Glaucoma?
Recent work has shown that diabetes is neither protective or a risk factor for
glaucoma when one has ocular hypertension and should not be used when deciding
whether to initiate therapy.
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7. What Harm will occur if we wait until glaucomatous damage is present?
An important question is whether glaucoma is like cancer, requiring early therapy to
prevent damage from accelerating over time. This assumption is one reason why
ocular hypertension is often treated. There is no data to support the concept of early
therapy or waiting at this time, and with the new tools for risk assessment we are
aiming preventive therapy at those most at risk.
8. Is Goldmann tonometry outdated? Should we adopt one of the new tonometers?
While Goldmann tonometry is 50 years old, we are comfortable with the data we
receive and understand how to use it. While not perfect, it will take awhile before the
newer instruments are adopted.
9. Is their a role for peripheral field testing in glaucoma?
Peripheral fields were evaluated 25 years ago and never adopted due to a host of
reasons including variability in the periphery. The peripheral threshold tests do not
offer probability limits because of the overlap between normal and abnormal results,
reducing its use to that of a screening test.
10. Is there a need for more sensitive perimetric tests such as FDT or SWAP?
A twenty year quest has been to improve the ability of visual fields to discover visual
field damage early on. SWAP and FDT are two tests meant to discover such change.
While they have problems, they do offer another method to explore the field.
11. Can the Matrix perimeter replace my standard one currently in use in the
management of my patients with glaucoma?
Perimeters are evolving and while the Matrix perimeter uses a different stimulus,
nonetheless it performs quite well and can be used in the management of glaucoma.
The larger issue is whether the instrument stores the data as well as has tools to
analyze the fields for change.
12. Have optic nerve imaging become a standard of care?
Standard of care issues are difficult to address and in fact evolve over time as the
instruments mature and become commonly used. Still imaging of any form is useful
and important to aid clinicians in recognizing early change as well as detecting
progressive loss.
13. What target IOP is needed to treat glaucoma?
Target IOPs are an important goal, and provide direction to the clinician. The target
IOP is related to the amount of damage present as well as the IOP level. Still no
magic number exists and it is a floating number as each case is individualized.
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