207
ARTICLE
Risk factors for and diagnosis of
pseudophakic cystoid macular edema
after cataract surgery in diabetic patients
Jin Yang, MD, PhD, Lei Cai, MD, Zhongcui Sun, MD, PhD, Hongfei Ye, MD, PhD, Qi Fan, MD, PhD,
Keke Zhang, MD, Wenyi Lu, OD, Yi Lu, MD, PhD
Purpose: To evaluate the risk factors and potential diagnostic
criteria for pseudophakic cystoid macular edema (CME) in diabetic
patients after phacoemulsification.
Setting: Department of Ophthalmology, Eye and ENT Hospital of
Fudan University, Shanghai, China.
Design: Prospective nonrandomized study.
Methods: Diabetic patients were followed for up to 6 months after
cataract surgery and examined to evaluate their foveal thickness,
macular sensitivity, and corrected distance visual acuity. Multiple
statistical analyses were performed to determine risk factors and
diagnostic criteria for pseudophakic CME.
Results: The duration, type of diabetes, stage of diabetic retinopathy, nuclear opalescence grading, glycosylated hemoglobin A1c (HbA1c), and ultrasound time were correlated with the
change in foveal thickness and macular sensitivity after cataract
D
iabetic mellitus increases the risk for cataract and
accelerates the progression of cataract in patients.1
With the increasing occurrence of cataract in diabetic patients, cataract surgery is a common procedure for
rapid visual rehabilitation.2,3 Unfortunately, surgery per se
might cause pseudophakic cystoid macular edema (CME)
or exacerbate diabetic retinopathy (DR) as a result of the
impaired blood–aqueous barrier in diabetic patients,4,5
although the advent of phacoemulsification and smallincision cataract surgery has significantly reduced the perioperative and postoperative complications.2,6 Prophylaxis
and management of pseudophakic CME remain challenging because of a lack of putative diagnostic criteria
surgery. Unsupervised data analysis showed 3 groups of
patients as follows: nonpseudophakic CME, level 1 pseudophakic CME, and level 2 pseudophakic CME. Subclinical level
1 patients had a 30% to 40% increase in foveal thickness
1 month postoperatively, while level 2 patients had at least a
40% increase in foveal thickness and a 20% decrease in macular sensitivity. The incidence of clinical pseudophakic CME
was 3.2% in diabetic patients as per the diagnostic criteria.
The change in macular sensitivity was more consistent and
correlated with foveal thickness.
Conclusions: The duration, severity, type of diabetes, hardness
of the lens, and HbA1c were risks for pseudophakic CME in diabetic
patients after cataract surgery. A 40% or more increase in foveal
thickness and 20% or more decrease in macular sensitivity offer
an objective and reliable diagnostic standard to report pseudophakic CME in diabetics.
J Cataract Refract Surg 2017; 43:207–214 Q 2017 ASCRS and ESCRS
and prospective randomized clinical trials.7,8 This lack is
a main cause of unfavorable visual outcomes after uneventful cataract surgery.
With better sensitivity and reproducibility, optical coherence tomography (OCT) has recently emerged as a noninvasive alternative approach to fluorescein angiography to
diagnose and monitor pseudophakic CME by detecting subtle changes in foveal thickness.9 Despite the worldwide application of OCT, different diagnostic criteria for pseudophakic
CME have been proposed, leading to a substantial variation
in the reported incidence.10,11 Apart from morphologic alterations in the central retina, subjective evaluation of macular
edema by visual acuity measurement and objective
Submitted: March 12, 2016 | Final revision submitted: October 31, 2016 | Accepted: November 14, 2016
From the Department of Ophthalmology (Yang, Cai, Sun, Ye, Fan, Zhang, W. Lu, Y. Lu), Eye and ENT Hospital of Fudan University, and the Myopia Key Laboratory of
Health PR China (Yang, Cai, Sun, Ye, Fan, Zhang, Y. Lu), Shanghai, China.
Drs. Yang and Cai contributed equally to this article.
Supported by the International Science and Technology Cooperation Foundation of Shanghai (no. 14430721100) and the Natural Science Foundation of Shanghai
(no. 16ZR1405200).
Corresponding author: Yi Lu, MD, PhD, Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital of Fudan University, Myopia Key Laboratory of
Health PR China, 83 Fenyang Road, Shanghai, China. E-mail: luyieent@126.com.
Q 2017 ASCRS and ESCRS
Published by Elsevier Inc.
0886-3350/$ - see frontmatter
http://dx.doi.org/10.1016/j.jcrs.2016.11.047
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DIAGNOSIS OF CME IN DIABETIC PATIENTS AFTER CATARACT SURGERY
examination of macular sensitivity by microperimetry provide functional assessment of an edematous macula.
To identify the risk factors for pseudophakic CME in diabetic patients and propose a reliable diagnostic standard, we
collected clinical data and combined noninvasive OCT and
microperimetry to evaluate the structure and function of
the macula. We also performed an unbiased populationbased quantification of the definition of pseudophakic CME.
PATIENTS AND METHODS
The study enrolled a consecutive cohort of diabetic patients with
normal preoperative foveal thickness scheduled for uncomplicated
phacoemulsification cataract surgery at Shanghai Eye and ENT
Hospital of Fudan University between March 2010 and July
2014. This study was approved by the Ethics Committee of Fudan
University and conducted in compliance with the Declaration of
Helsinki developed by the World Medical Association. Informed
consent was obtained from all patients.
Exclusion criteria were previous intraocular surgery of any type
or a history of laser photocoagulation within 3 months before
phacoemulsification; a history of uveitis, nondiabetic retinal disease, or choroidal disorders; diabetic macular edema or abnormal
retinal thickening diagnosed by OCT before surgery; proliferative
retinal retinopathy; and inadequate quality of preoperative OCT
images or fundus photograph images. The diabetic patients were
classified into insulin-dependent and noninsulin-dependent
groups, and their glycosylated hemoglobin A1c (HbA1c) was
measured for correlation analysis.
Patient Assessment
Before cataract surgery, all eyes had a comprehensive ophthalmologic examination. The grading of nuclear opalescence was determined according to the Lens Opacities Classification System
III.12,13 Fundus photography and an OCT examination were performed fewer than 3 months before surgery and 4 weeks before surgery, respectively. The level of DR was evaluated using fundus
photography and recorded as none, mild, moderate, or severe nonproliferative retinopathy.14 The cumulative dissipated energy
(CDE) and ultrasound (US) time were recorded as main system parameters during cataract surgery. Patients were followed 1 week,
1 month, 3 months, and 6 months postoperatively. At each visit,
the eyes were examined with OCT and microperimetry to assess
postoperative rehabilitation. In addition, the corrected distance visual acuity (CDVA) was measured using a logMAR chart.
Foveal Thickness Measurement
After pupil dilation, the patients’ eyes were scanned with the Spectralis HRA plus OCT device (Heidelberg Engineering GmbH) by
skilled physicians and medical technicians to obtain OCT images.
The patients received volume scans comprising 36 high-resolution
slices with 30 ART frames (20 degrees 15 degrees) centered on
the fovea. Each slice was yielded by 512 single A-scans, and the interval between the slices was 116 mm. The scanned area at the posterior pole covered 6000 mm in width and 4500 mm in height. The
center of the fovea was determined from the location of foveal
depression, foveal intraretinal layer convergence, central photoreceptor detachment, and position relative to the optic nerve head.
Line errors were adjusted using Heidelberg software. The foveal
thickness values were determined by scaling the macular thickness
in the central point of the fovea. The data were collected 1 month
before cataract surgery (baseline) and 1 week, 1 month, 3 months,
and 6 months after surgery.
Microperimetry Test
The macular sensitivity in all eyes was examined with a perimeter
(MP-1, Nidek Technologies Srl). The dominant eye of the patient
Volume 43 Issue 2 February 2017
was dilated and adapted to a background of 1.27 candelas/m2 illumination for 15 minutes. The patient was directed to fixate on the
target mark. The eye-tracking system was used to monitor the eye
shift relative to a distinct fundus marker (major vessels or optic
nerve head). In the automated pattern, each test consisted of a
4–2–1 staircase strategy on a mire of 45 Goldmann III stimuli
covering the central 12 degrees of the visual field. Stimulus intensity, ranging from 0 to 20 dB, was titrated in 1 dB steps. The
response of the patients was recorded, and all stimuli were documented on the fixed infrared fundus photograph acquired by a
charge-coupled color camera at the onset of the tests. To obtain
more objective data from patients, the duration of each test within
was restricted 15 minutes to avoid a fatigue-induced lack of
response to stimuli. Moreover, a false-positive test stimulus was
projected onto the optic nerve head area at 60-second interval to
check the status of eyes. Any patient giving a false-positive
response was required to take a 2-hour break before reexamination. The documented macular sensitivity was the mean value
from 45 stimuli during the test.
Surgical Technique
All phacoemulsification surgeries were performed by the experienced surgeon (L.Y.) using the Infiniti Vision System (Alcon Laboratories, Inc.). Briefly, after topical anesthesia was administered, a
2.4 to 2.6 mm long self-sealing clear corneal incision was created.
This was followed by capsulorhexis, hydrodissection, phacoemulsification, manual aspiration of the cortex, and implantation of a
foldable intraocular lens (Tecnis ZCB00 or Tecnis ZA9003, Abbott
Medical Optics, Inc.; Acrysof IQ SN60WF, Alcon Laboratories,
Inc.; Superflex Aspheric 970C/920H, Rayner Intraocular Lenses
Ltd.). No suture was required, and all incisions were checked to
make sure they self-sealed. Postoperatively, topical prednisolone
acetate 1.0% was given 4 times a day for 2 weeks and then 3 times
daily for another week, pranoprofen 0.1% was given 4 times a day
for 6 weeks, and levofloxacin 0.5% was applied to the eyes of diabetic patients.
Monitoring and Identification of Risk Factors for Macular
Edema
To monitor the postoperative macular edema in diabetic patients, the baseline and postoperative foveal thickness, macular
sensitivity, and CDVA values were assessed. To identify potential
risk factors for postoperative macular edema other than surgical
complications, uveitis, and retinal macular edema, the differential values between baseline and the 1-month postoperative evaluation were analyzed to obtain the change in foveal thickness,
macular sensitivity, and CDVA. This was followed by correlation
analyses of the basic clinical characteristics of patients, including
the duration and types of diabetes, grading of nuclear opalescence, and stage of DR.
Suggested Diagnostic Standard of Pseudophakic Cystoid
Macular Edema
The absolute threshold for thickening macula, the relative increase
over normal control population, and the percentage increase from
baseline have been proposed to diagnose pseudophakic CME. To
avoid biased and subjective diagnosis of pseudophakic CME in a
diabetic population, a data matrix including 6 continuous variables (increase in foveal thickness, decrease in macular sensitivity,
change in CDVA, HbA1c, CDE, and US time) was generated for
1002 patients. An unsupervised hierarchical clustering analysis
was performed based on the Euclidean distance among patients.
The Euclidean distance was based on the following 6 continuous
variables: the change in foveal thickness, macular sensitivity, and
CDVA; cumulated dissipated energy (CDE); HbA1c; and US
time for hierarchical clustering analysis. The clustering analysis
and distance matrix subdivided the patients into 3 groups as follows: nonpseudophakic CME, level 1 pseudophakic CME, and
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DIAGNOSIS OF CME IN DIABETIC PATIENTS AFTER CATARACT SURGERY
level 2 pseudophakic CME. To evaluate the compromised visual
function in pseudophakic CME patients, the percentage change
in macular sensitivity and CDVA from 1 week to 1 month postoperatively was further quantified.
Macular Sensitivity as a Functional Parameter in
Diagnostic Criteria for Pseudophakic Cystoid
Macular Edema
The structural change in the macula and the functional compromise have been suggested as diagnostic markers of pseudophakic
CME. As 1 of the most significant clinical findings in pseudophakic CME patients, a compromised CDVA does not have a
strong correlation with macular thickness.
The consistency of macular sensitivity and CDVA change from
baseline values to postoperative values was analyzed. Also analyzed
was the linear relationship between the increase in foveal thickness
1 month postoperatively and the decrease in macular sensitivity or
the change in CDVA at different postoperative timepoints.
Statistical Analysis
All values are expressed as the mean G SD. Statistical analyses
were performed using SAS, Graphpad Prism, and R software.
The 1-sample Kolmogorov-Smirnov test was used to evaluate
normal distribution of continuous variables before statistical significance was analyzed. Variables from 2 groups were compared
using a 2-tailed Student t test or 2-way repeated-measures analysis
of variance. Statistical analyses of multiple-group comparison
were corrected by the Bonferroni post hoc test. Correlation analyses between multiple groups and the distance matrix were generated by an in-house R script without artificial intervention.
Spearman correlation coefficients were computed, which together
with multiple linear regression, were applied to seek risk factors for
pseudophakic CME. The statistical analysis results were considered significant at a P value of less than 0.05.
RESULTS
The study enrolled 1200 patients. After excluding 8 patients with intraoperative or postoperative complications
and 190 patients who did not complete the 6-month
follow-up assessment, 1002 eyes of 1002 patients (511
men, 491 women) were included in the final analyses.
Table 1 shows the basic characteristics of patients with a
long duration (R5 years) or short duration (!5 years)
of diabetes mellitus.
Risk Factors for Postoperative Macular Edema
in Diabetics
Figure 1 shows the quantitative analyses of the CDE, US
time, grade of nuclear opalescence, change in foveal thickness and macular sensitivity from baseline to 1 month
postoperatively in different population of diabetic patients. It also shows the correlation analysis of the increase
in foveal thickness, decrease in macular sensitivity, change
in CDVA, CDE, HbA1c, and US time. The macular sensitivity and CDVA improved significantly after phacoemulsification (Table 2). However, the macular thickness
peaked 1 month after surgery (Table 2). Patients with a
longer duration of diabetes, insulin dependence, less nuclear transparency, or more severe DR had a worse postoperative outcome (Figure 1).
Correlation analysis of continuous variables (eg,
HbA1c, CDE, US time) by linear regression showed
that although these continuous variables had only a
Table 1. Patient demographics.
Parameter
Patients (n)
<5 Years
521
R5 Years
481
P Value
d
Eyes
O.05
Sex (n)
Male
260
234
Female
261
247
Mean age (y) G SD
Mean HbA1c (%) G SD
66.9 G 6.1
68.8 G 7.6
!.05
6.8 G 0.8
7.1 G 0.9
!.05
Diabetes type (n)
Noninsulin dependent
287
205
!.05
Insulin dependent
234
276
!.05
None
101
35
!.05
Mild NPDR
157
108
!.05
Moderate NPDR
166
153
!.05
97
185
!.05
Magnitude of DR (n)
Severe NPDR
NO
2.6
2.8
!.05
DR Z diabetic retinopathy; HbA1c Z glycosylated hemoglobin A1c; NO Z nuclear
opalescence; NPDR Z nonproliferative diabetic retinopathy
slight correlation with the postoperative change in
macular sensitivity and CDVA, there was a positive
correlation between the change in foveal thickness and
the level of HbA1c or US time (Figure 1). Taken
together, the results suggest that the parameters diabetes
and lens are potential risk factors for postoperative
macular edema.
Suggested Diagnostic Standard of Pseudophakic Cystoid
Macular Edema
Analysis of the percentage increase in foveal thickness
from baseline to 1 month postoperatively showed perfect
segregation of 3 clusters of patients as follows: nonpseudophakic CME, greater than 30% increase
(n Z 955); level 1 pseudophakic CME, 30% to 40% increase (n Z 15), and level 2 pseudophakic CME, greater
than 40% increase (n Z 32) (Figure 2, B). Despite the immediate visual rehabilitation after cataract surgery, a
reduction in macular sensitivity and CDVA caused by
postoperative macular edema occurred 1 week after surgery (Figure 2, C and D).
Regarding compromised visual function in pseudophakic
CME patients, from 1 week to 1 month postoperatively
there was no reduction in macular sensitivity in the nonpseudophakic CME group, a 20% decrease in the pseudophakic level 1 CME group, and a 30% decrease in the level
2 pseudophakic CME patients on average (Figure 2, C).
The reduction in CDVA in the level 2 pseudophakic
CME group was significant compared with that in the
nonpseudophakic CME group (Figure 2, D). The slight difference between the level 1 pseudophakic CME group and
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DIAGNOSIS OF CME IN DIABETIC PATIENTS AFTER CATARACT SURGERY
Figure 1. Risk factors for postoperative
macular edema. Quantitative analysis
of CDE (A and B), US time (C and D),
the grade of nuclear opalescence
(E and F), and the change in foveal
thickness (G and H) and in macular
sensitivity (I and J) from baseline to
1 month postoperatively in different
population of diabetic patients. The
data are shown as mean G SD. K: Correlation analysis of the increase in
foveal thickness (DFT), decrease in
macular sensitivity (DMS), change in
CDVA (DCDVA), CDE, HbA1c, and US
time. The Spearman correlation coefficients were converted into a heat map
(CDE Z cumulative dissipated energy;
HbA1c Z glycosylated hemoglobin A1c;
IDDM Z insulin-dependent diabetes
mellitus; mpo Z months postoperative; NIDDM Z noninsulin-dependent
diabetes mellitus; NO Z nuclear opalescence; US Z ultrasound).
nonpseudophakic CME group suggested that patients with
a 30% to 40% increase in foveal thickness could be diagnosed as having subclinical pseudophakic CME. Patients
with at least a 40% increase in foveal thickness from
Volume 43 Issue 2 February 2017
baseline and a 20% decrease in macular sensitivity from
1 week postoperatively could be diagnosed as having clinical pseudophakic CME, the incidence of which was 3.2%
in this study.
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DIAGNOSIS OF CME IN DIABETIC PATIENTS AFTER CATARACT SURGERY
Table 2. Change in foveal thickness, macular sensitivity, and CDVA over time.
Mean ± SD
Postoperative
Parameter
Foveal thickness (mm)
Macular sensitivity (dB)
CDVA (logMAR)
Baseline
1 Week
1 Month
3 Months
6 Months
247.2 G 7.6
257.3 G 9.4
283.5 G 34.9
267.0 G 28.5
251.0 G 24.3
9.4 G 2.6
13.1 G 2.0
13.4 G 2.4
13.4 G 2.2
13.2 G 2.1
0.51 G 0.14
0.19 G 0.10
0.183 G 0.12
0.17 G 0.09
0.19 G 0.10
CDVA Z corrected distance visual acuity
Macular Sensitivity as a Functional Parameter
in Diagnostic Criteria for Pseudophakic Cystoid
Macular Edema
Thirteen (87%) level 1 pseudophakic CME patients and 14
(44%) level 2 pseudophakic CME patients did not have
compromised visual acuity 1 month after surgery
(Figure 2, D). Thus, the correlation of another functional
parameter, visual field sensitivity, with macular thickness
Figure 2. Diagnostic criteria for pseudophakic CME revealed by unsupervised hierarchical clustering analysis. A: Distance matrixbased heat map results of unbiased hierarchical clustering analysis.
B: The increase in foveal thickness 1 month postoperatively from
baseline. C and D: Change in macular sensitivity and CDVA. The
data are shown as mean G SD (* Z P ! .05; *** Z P ! .001;
CDVA Z corrected distance visual acuity; FT Z foveal thickness;
mpo Z months postoperative; MS Z macular sensitivity;
PCME Z pseudophakic cystoid macular edema; I-PCME Z level
1 pseudophakic cystoid macular edema; II-PCME Z level 2 pseudophakic cystoid macular edema).
was evaluated. First, the chronological trajectory of the
mean foveal thickness, macular sensitivity, and CDVA
showed that macular sensitivity dynamics functionally reflected the structural change in the macula better than
CDVA (Figure 3, A to C). The large peaks and valleys in
the curve of CDVA in level 2 pseudophakic CME patients
suggest extreme variation in this group's subjective visual
function (Figure 3, C). Regarding consistency, the changes
in macular sensitivity at different postoperative stages
were more highly correlated with one another than the
alteration in CDVA (Figure 3, D and E). Finally, the linear
relationship between the increase in foveal thickness
1 month postoperatively and the decrease in macular sensitivity or the change in CDVA at different postoperative
timepoints showed that the change in macular sensitivity
was more negatively correlated with the change in foveal
thickness than with the change in CDVA, especially at
the peak of macular thickening after surgery (Figure 3, F).
These data together suggest macular sensitivity must be
included as a functional parameter in the diagnosis and
prognosis of pseudophakic CME.
DISCUSSION
Our study with a large sample found more risk factors for
pseudophakic CME and might provide potential diagnostic
criteria for this common cause of visual loss after uneventful cataract surgery in diabetic patients.15 The results in this
prospective study would lay a foundation for future randomized clinical trials to treat pseudophakic CME in diabetic patients.
Noninvasive spectral-domain OCT, a relatively new diagnostic tool, is fast and provides high-resolution imaging of
the retina to detect subtle changes in foveal thickness.
Although OCT has not replaced fluorescein angiography
to diagnose diabetic macular edema and retinal vein occlusion as the gold standard, the technique has been widely
adopted to provide definite evidence for the diagnosis of
pseudophakic CME.7–9 The development of the MP-1 microperimeter includes an autotracking system to facilitate
the accurate measurement of macular sensitivity within
the central visual field and incorporates a color fundus camera for image registration.16 Microperimetric assessment
has become an important adjunct to traditional CDVA
test for evaluating visual function. In this study,
we excluded all patients with macular edema before surgery.
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DIAGNOSIS OF CME IN DIABETIC PATIENTS AFTER CATARACT SURGERY
Figure 3. Correlation between
structural change and visual function. Chronological trajectory of FT
(A), macular sensitivity (B), and
CDVA (C) in nonpseudophakic
CME, level 1 pseudophakic CME,
and level 2 pseudophakic CME patients from preoperatively to
6 months postoperatively. The
data are shown as mean G SD.
D: Correlation and linear regression
analysis of postoperative change in
macular sensitivity at 1 week,
1 month, 3 months, and 6 months
shows consistent change of macular sensitivity at different timepoints. E: Correlation analysis of
the change in CDVA over time. F:
Heat map showing Spearman correlation
coefficients
between
change in foveal thickness at
1 month and CDVA and macular
sensitivity over time by group
(** Z P ! .01; *** Z P ! .001;
D Z change; CDVA Z corrected
distance visual acuity; FT Z foveal
thickness; mpo Z months postoperative; MS Z macular sensitivity;
PCME Z pseudophakic cystoid
macular edema; I-PCME Z level 1
pseudophakic cystoid macular
edema; II-PCME Z level 2 pseudophakic cystoid macular edema;
wpo Z weeks postoperative).
Because the cause of macula edema is not distinguished by
OCT or microperimetery, we cannot completely rule out
that diabetic macular edema can occur 1 week after surgery.
However, we believe that phacoemulsification surgery is
still the dominant cause for macular edema soon after
surgery.
We correlated the change in foveal thickness, macular
sensitivity, and CDVA 1 month postoperatively with clinical data to determine risk factors for CME and found that
a long duration (R5 years) of diabetes, insulin dependence, nuclear opacity, severe DR, elevated HbA1c, and
long US time conferred a high risk for postoperative macular edema in diabetic patients. Based on studies with
small samples,17 diabetics with a long duration of the disease are more susceptible to developing DR and further
progress to macular edema after phacoemulsification.
The exclusion of patients with diabetic macular edema
in our large sample confirmed the association of duration
and type of diabetes and the stage of DR with macular
edema and reduced visual acuity, which is consistent
with results in a previous study.17 We further identified
new risk factors for pseudophakic CME, including nuclear
Volume 43 Issue 2 February 2017
opacity, HbA1c, and US time. Patients with an HbA1c
higher than 7 mg/dL or US time longer than 50 milliseconds are more susceptible to pseudophakic CME after
cataract surgery. Although the level of HbA1c reflects
the severity of the DR, more US energy is required to
emulsify harder lenses, which might result in the release
of inflammatory factors after surgery and exacerbate macular edema.
Furthermore, our study provides diagnostic criteria for
pseudophakic CME. In the literature, the lack of a putative
diagnostic standard leads to variable reported incidence of
pseudophakic CME in cataract patients, ranging from less
than 1% to 70%.3,7,8,10,18 More important, setting an absolute
threshold and a relative increase over a control population to
diagnose pseudophakic CME would not rule out the interpatient and inter-institution variability. A previous study10
enrolled patients with diabetes, those with uveitis, and
healthy controls who had cataract surgery and suggested a
postoperative increase in macular thickness of 40% or
more as a way to diagnose pseudophakic CME. However,
previous studies19,20 analyzed small samples with a mixed
population and subjectively defined patients with macular
DIAGNOSIS OF CME IN DIABETIC PATIENTS AFTER CATARACT SURGERY
edema ahead of proposing a diagnostic standard. In this
study, we analyzed 1002 diabetic patients using an unbiased
data-analysis approach and proposed that subclinical pseudophakic CME patients have a 30% to 40% increase in foveal
thickness from baseline as determined by OCT, while a 40%
increase in foveal thickness and 20% decrease in macular
sensitivity 1 month postoperatively could be a more reliable
and valid diagnostic standard for clinical pseudophakic CME
in diabetic patients. A reduction in visual acuity is not consistently correlated with morphologic changes in the macula in
patients.21 Even though there was a negative correlation between the change in foveal thickness and CDVA in our
study, 87% of level 1 pseudophakic CME patients and 42%
of level 2 pseudophakic CME patients did not have compromised visual acuity after visual rehabilitation. Therefore, it is
unsuitable to include CDVA in the diagnostic criteria. With
the suggested diagnostic standard, the incidence of clinical
pseudophakic CME in diabetic patients is 3.2%.
The application of modern cataract surgery and administration of prednisolone acetate 1.0% for 3 weeks and pranoprofen for 6 weeks after surgery are considered to have
reduced the incidence of pseudophakic CME in the present
study. Previous studies22,23 found that a combination of
topical corticosteroids and nonsteroidal antiinflammatory
drugs (NSAIDs) reduces the risk for developing pseudophakic CME after cataract surgery compared with using
single-drug treatment of corticosteroids. It has been suggested that using NSAIDs before surgery in diabetic patients
also reduces the incidence of pseudophakic CME and hastens the visual recovery in the immediate postoperative
period.22,24 However, there is no direct evidence to suggest
that the prophylactic use of NSAIDs reduces the incidence
of angiographic or OCT-based pseudophakic CME longer
term (O3 months) or reduces vision loss from pseudophakic
CME after cataract surgery. In this study, we did not use
NSAIDs preoperatively. In the future, we plan to use
NSAIDs 3 days before surgery in high-risk patients, such
as those with diabetes, and to evaluate the incidence of pseudophakic CME after cataract surgery. Macular sensitivity
measured by microperimetry provides a thorough evaluation
of macular disorders such as age-related macular degeneration, myopic maculopathy, macular dystrophies, and diabetic macular edema.25,26 We included the change in
macular sensitivity assessed by microperimetry into diagnostic criteria for clinical pseudophakic CME for the
following reasons: First, the temporal dynamics of macular
sensitivity reliably reflect the structural change in the macula
after cataract surgery. Second, the postoperative change in
macular sensitivity is more consistent at different timepoints
and more correlated with macular thickness than with
CDVA. Our results suggest that macular sensitivity serves
as a more sensitive, consistent, and reliable way to evaluate
the function of the retina.
In conclusion, this study identified several risk factors for
postoperative macular edema that deserve more attention
of clinicians pertaining to the management of cataract patients with diabetes. Notably, we suggest a 40% increase
in foveal thickness and 20% decrease in macular sensitivity
213
as diagnostic criteria for clinical pseudophakic CME and
report that 3.2% of diabetic patients developed pseudophakic CME after cataract surgery. These patients should
be selected for future clinical trials for preventing and treating pseudophakic CME.
WHAT WAS KNOWN
Pseudophakic CME is an important cause of visual decline
after uncomplicated cataract surgery, and the incidence
may be even higher in diabetic patients. Optical coherence
tomography has recently emerged as an alternative to
fluorescein angiography for diagnosing pseudophakic CME.
However, the putative diagnostic standard of pseudophakic
CME and the true incidence of pseudophakic CME in large
numbers of diabetic patients after cataract surgery have not
been defined clearly.
WHAT THIS PAPER ADDS
The combination of OCT and microperimetry was an
effective method to evaluate the macular function after
phacoemulsification in cataract patients with diabetes. Results show that an increase in foveal thickness of 40% might
be an appropriate cutoff for diagnosing clinically relevant
pseudophakic CME.
The incidence of pseudophakic CME determined from OCT
plus microperimetry testing might provide more precise risk
stratification and translate ultimately into more timely treatment and targeted prophylaxis for patients with high-risk
characteristics.
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Disclosure: None of the authors has a financial or proprietary interest in any material or method mentioned.
First author:
Jin Yang, MD, PhD
Department of Ophthalmology, Eye and
ENT Hospital of Fudan University,
Shanghai, China