Cataract surgery for congenital cataract: Endothelialcell characteristics, corneal thickness, and impact onintraocular pressureNaveed Nilforushan, MD,a Khalil Ghasemi Falavarjani, MD,a Mohammad Reza Razeghinejad,b

and Pejman Bakhtiari, MDa

PURPOSE To investigate whether central corneal thickness (CCT), endothelial cell characteristics,and intraocular pressure (IOP) are affected in patients with previous congenital cataractsurgery and to focus on their clinical significance.

METHODS CCT and IOP measurements and specular microscopy were performed in 31 eyes of 17cases of extracted congenital cataracts and 40 eyes of 20 age- and sex-matched participantsas control group. The mean of three pachymetry measurements of the central cornea wastaken as CCT. IOP was checked using an applanation tonometer.

RESULTS The mean corneal thickness of the eyes with extracted congenital cataract (632 � 45 �m)was significantly greater than that of the control eyes (546 � 33 �m; p � 0.001). Therewas no significant difference in the corneal endothelial cell count, coefficient of variation(CV), and mean cell area (AVG) of endothelial cells between operated eyes and thecontrol group. The mean measured IOP in the operated group (22.8 � 3.3 mm Hg) wassignificantly greater than IOP in controls (14.1�1.8 mm Hg, p � 0.001).

CONCLUSIONS Although the corneas were clinically clear and there was no significant difference inendothelial characteristics of eyes with extracted congenital cataract and controls, centralcorneas of operated eyes were significantly thicker than those of controls. To differentiatethe actual glaucoma from ocular hypertension in these patients, the central cornealthickness measurement should strongly be considered. ( J AAPOS 2007;11:159-161)

C ongenital cataracts are an important cause of visualimpairment in infants and children.1 Cataract sur-gery is performed early to prevent amblyopia;

however, early surgery can affect the structure of theeye,2,3 including the cornea.4-6

The risk of glaucoma among aphakic children has beendemonstrated to be as high as 32% in previous studies.7-9

However, the diagnosis of glaucoma in these reports hasrested primarily on intraocular pressure (IOP) measure-ment7,10 and increasing evidence has suggested that IOP maybe influenced by central corneal thickness (CCT).11-15

In practice, we have encountered numerous patientswho underwent surgery for congenital cataract and hadelevated IOP without any other signs suggesting glau-coma. Many of these pseudophakic or aphakic patientsmay actually be ocular hypertension cases.10,16 We evalu-

Author affiliations: aEye Research Center, Iran University of Medical Science, Tehran,Iran; bKhalili Hospital, Shiraz University of Medical Science, Shiraz, Iran

None of the authors have any financial interest in the subject matter of this article.Submitted May 24, 2006.Revision accepted August 30, 2006.Published online November 2, 2006.Reprint requests: Khalil Ghasemi Falavarjani, Eye Research Center, Rasool Akram

Hospital, Sattarkhan Avenue, Tehran, Iran (email: drghasemi@yahoo.com).Copyright © 2007 by the American Association for Pediatric Ophthalmology and

Strabismus.

1091-8531/2007/$35.00 � 0doi:10.1016/j.jaapos.2006.08.017

Journal of AAPOS

ated the CCT, IOP, and endothelial characteristics inpatients who underwent cataract surgery for congenitalcataract and compared these measurements to those ofchildren without congenital cataracts.

Patients and methodsThirty-one eyes of 17 patients (8 boys and 9 girls) with a meanage of 12.7�6.6 years who had undergone limbal approachlensectomy/anterior vitrectomy for congenital cataract wereevaluated. These included 14 bilateral and 3 unilateral cataractextractions. The mean age at the time of the cataract operationwas 19.58 � 19.08 (range, 2-72) months. The mean time offollow-up between cataract surgery and assessments was 10.7 �

6.08 years. All of the selected patients had clear corneas withhorizontal corneal diameters of 10.5-11.5 mm on slit-lamp ex-amination at the time of evaluation. Forty eyes of an age- andsex-matched group of 20 normal volunteers who visited thegeneral eye clinic for routine eye examinations were used ascontrols. All patients or their parents (for children) signed aninformed consent. The Institutional Review Board of Iran Uni-versity of Medical Sciences approved the study.

The corneal thickness was measured during the day ( between10 AM and 2 PM) with a pachymeter (Paxis, Biovision Inc.,Clermont Ferrand, France). The corneal thickness was measuredthree times at the center of each cornea and the mean of these

three measurements was used if their SD was less than 0.005 mm.

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Volume 11 Number 2 April 2007160 Nilforushan et al

The indices of corneal endothelial cells were measured byspecular microscopy (SP2000, Topcon Corp., Tokyo, Japan).For each eye the mean of measurements made on three micro-graphs was calculated.

The IOP was measured during the day ( between 10 AM and2 PM) by a Goldman applanation tonometer. All IOPs (includingpatients and controls) were measured by one examiner using onetonometer.

Patients with any structural eye disease other than congenitalcataract (including congenital glaucoma and any corneal opacity)and those with glaucomatous optic nerve damage were excludedfrom the study.

Statistical analyses were performed with SPSS for Windows V11.5 (SPSS, Chicago, IL, USA) using the independent t-test andMann-Whitney test. Differences were considered to be statisti-cally significant when p � 0.05.

ResultsTable 1 shows corneal thickness, endothelial characteris-tics, and intraocular pressure in eyes with congenital cat-aract extraction and controls.

The mean corneal thickness of eyes with extracted con-genital cataract (632 � 45 �m) was significantly greaterthan that of control eyes (546 � 33 �m; p � 0.001). Therewas no significant difference in the corneal endothelial cellcounts among the operated eyes (3454 � 450 cells/mm2)and the control eyes (3470 � 527 cells/mm2, p � 0.93).There was no significant difference in the coefficient ofvariation (CV) in the cell size between operated eyes(19.5 � 6) and controls (22 � 5, p � 0.4).

Mean cell area (AVG) of endothelial cells was 311 �26 �m2 for the operated group and 306 � 36 �m2 forcontrol group, which did not represent a significantdifference ( p � 0.71). The mean measured IOP in theoperated group (22.8 � 3.3 mm Hg) was significantlygreater than IOP in controls (14.1 � 1.8 mm Hg,p � 0.001).

In the operated group, there was a relationship betweencentral corneal thickness and IOP (linear regression anal-ysis, p � 0.002; Figure 1). In this model, IOP increases 4.8mm Hg for every 100 �m increase in central cornealthickness. Analysis of the relationship between IOP andcentral corneal thickness in controls revealed an IOP in-crease of 3.1 mm Hg for each 100 �m increase in central

Table 1. Corneal thickness and endothelial characteristics in eyes with

Corneal thickness (�m)Endothelial cell counts ( per mm2)Coefficient of variationMean cell area (�m2)Intra-ocular pressure (mmHg)Adjusted intra-ocular pressure (mmHg) for central corneal thickness‡

* Mean � standard deviation.† Student’s t-test.‡ Based on linear regression analysis of study data.

corneal thickness (linear regression analysis, p � 0.000).

DiscussionCongenital cataracts interfere with normal visual develop-ment and represent an important problem in pediatricophthalmology.1 Early removal of visually significant cat-aracts is probably the most important factor in determin-ing the visual outcome of these eyes.1 However, early lensremoval induces anatomic and physiologic changes in eyeswith extracted congenital cataract.2,3

Our results showed that the corneas of the eyes withextracted congenital cataract were significantly thickerthan the corneas of children without congenital cataracts.Also there was significant elevation of IOP in these eyes.The endothelial cell count and morphology were not sig-nificantly different from the control group.

The significantly thicker corneas could falsely elevateapplanation pressures.12-15 Thus appropriate criteria fordiagnosing glaucoma in children who have had cataractextractions warrant careful consideration. Minor eleva-tions in IOP may be of less concern in children with thickcorneas.10 It is clearly preferable to include measures ofstructural and functional optic nerve changes when follow-

ital cataract extraction and controls

Control group* Cataract extracted eyes* p-value†

546 � 33 632 � 45 p � 0.0013470 � 527 3454 � 450 p � 0.93

22 � 5 19.5 � 6 p � 0.4306 � 36 311 � 26 p � 0.7114.1 � 1.8 22.8 � 3.3 p � 0.00113.9 � 1.2 18.7 � 3 p � 0.001

Central corneal thickness (microns)

800700600500

Intr

aocu

lar

pres

sure

(m

mH

g)

32

30

28

26

24

22

20

18

16

FIG 1. Relationship between central corneal thickness and intraocularpressure for children who have had cataract extractions. Linear regressionanalysis yields a nonzero slope ( p � 0.002), with a value of 0.048 (mmHg increase in IOP/1 �m increase in central corneal thickness).

congen

ing these patients over time.16 Our study supports the

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Volume 11 Number 2 April 2007 Nilforushan et al 161

importance of CCT measurement in the presence of ele-vated IOP in pseudophakic/aphakic children.

Some reports6,10,17 in the past speculated that the in-creased CCT in children who have had cataract extrac-tions may be due to the endothelial damage at the time ofsurgery or after that. Simon et al reported that compro-mise of endothelial function may have resulted from sur-gical trauma due to manipulation or irrigation solutions orfrom postoperative inflammation. Impaired endothelialfunction has been proposed to increase corneal thick-ness.10,17 It is noteworthy that none of our patientsstudied had clinically identifiable corneal edema as aresult of impaired endothelial function and also that theendothelial characteristics were not significantly differ-ent from controls.

Amino et al6 evaluated the corneal thickness followingpars plana lensectomy for 24 eyes with congenital cataractsand compared the results with those of 15 normal eyes.They found an increase in CCT after surgery. They alsoreported the endothelial characteristics and found signifi-cant differences in the frequency of hexagonally shapedendothelial cells and in the coefficient of variation in theendothelial cell size, but the difference of endothelial cellcount was not statistically significant. They proposed thatthe mechanical stress during cataract surgery can alsodamage the corneal endothelial cells and cause cornealthickening. They did not state the corneal status in termsof edema and clarity, however. Also, technical difficultiesfor specular microscopy in children and some differencesin the sample size of cases and controls may explain thevariance of their endothelial findings with our results.

Our study clearly shows that another cause should beconsidered to explain increased CCT. One plausible ex-planation for the increased corneal thickness in childrenwho have had cataract extractions is an association be-tween CCT and cataract in the pediatric population; eyeswith congenital cataracts may have thicker corneas. An-other possible explanation is a developmental change. Forexample, lens extraction in early childhood affects oculargrowth, and retardation of axial elongation after cataractsurgery in infants has been reported.1 Embryological in-vestigations have shown that the formation and develop-ment of the cornea is induced by the lens.18 Furthermore,several studies have reported a decrease in corneal thick-ness with age.2 These developmental changes to the cor-nea might have been interrupted by the lens extraction inthe early period of life, and as a result, the corneas of theeyes with extracted congenital cataract might have becomethicker relative to those of the controls.

This study has some limitations. Preoperative measure-

ments of CCT and endothelial characteristics, with com-

Journal of AAPOS

parisons to postoperative data, would help to elucidate thecause of changes in corneal thickness. Also, a larger samplesize would enhance our analysis.

Despite these limitations, we believe that, in childrenwho have had cataract extractions when IOP is elevated,CCT should be measured to aid in its interpretation.

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