ARTICLE

Changes in centra

l corneal thicknessafter congenital cataract surgery

Amir Faramarzi, MD, Mohammad Ali Javadi, MD, Mohammad Hossein Jabbarpoor Bonyadi, MD,Mehdi Yaseri, MS

Q 2010 A

Published

SCRS an

by Elsev

PURPOSE: To evaluate central corneal thickness (CCT) changes after congenital cataract surgerywith or without intraocular lens (IOL) implantation.

SETTING: Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Beheshti University ofMedical Sciences, Tehran, Iran.

DESIGN: Comparative case series.

METHODS: Anterior lensectomy and anterior vitrectomy were performed in eyes with congenitalcataract. Eyes had IOL implantation (pseudophakic group) or remained aphakic (aphakic group).The CCT and intraocular pressure were measured in all cases preoperatively and 1 and 6 monthspostoperatively. Age-matched normal eyes served as a control group.

RESULTS: The study evaluated 47 eyes (30 patients), 32 pseudophakic and 15 aphakic. The meanpreoperative CCT was 540 mmG 34 (SD) in the pseudophakic group, 548G 61 mm in the aphakicgroup, and 558G 36 mm in the control group (PZ .207). The mean CCT in the aphakic group wassignificantly greater than in the pseudophakic group (587G 65 mm versus 539G 37 mm) 1 monthpostoperatively (P Z .018) and at 6 months (602 G 65 mm versus 540 G 36 mm) (P Z .012).Although the CCT values in the pseudophakic group at 1 month and 6 months were similar to pre-operative values (P Z .463 and P Z 1.00, respectively), both postoperative CCT values in theaphakic group were significantly greater than preoperatively (P<.001).

CONCLUSIONS: The CCT in eyes with congenital cataract was similar to that in normal age-matchedeyes. However, shortly after cataract removal, the CCT was significantly greater in aphakic eyes thanin pseudophakic eyes.

Financial Disclosure: No author has a financial or proprietary interest in any material or methodmentioned.

J Cataract Refract Surg 2010; 36:2041–2047 Q 2010 ASCRS and ESCRS

Increased central corneal thickness (CCT) after re- compared with that in normal eyes? (2) Does cataract

moval of a congenital cataract has been reported.1–5

It is unclear whether the increased CCT is present be-fore surgery or develops postoperatively. Most inves-tigators believe the change occurs postoperatively.1,4

Some suggest that surgical trauma at the time of cata-ract extraction may compromise endothelial cell func-tion and result in increased CCT in these patients.3,5

In adults6–9 and in children,10 a thicker central cor-nea is associated with higher intraocular pressure(IOP) readings by Goldmann applanation tonometry.The thickened cornea after congenital cataract extrac-tion can lead to overestimation of IOP readings andcause over diagnosis of aphakic glaucoma with over-use of antiglaucoma medications.

In this study, we sought to answer 2 questions: (1) Isthe CCT increased in eyes with congenital cataract

d ESCRS

ier Inc.

extraction (with or without intraocular lens [IOL] im-plantation) have an effect on CCT? To answer thesequestions, we measured the CCT in eyes with conge-nital cataract preoperatively and compared the resultswith those in normal age-matched eyes. We continuedtomeasure the CCT for 6months after cataract surgeryin aphakic eyes and pseudophakic eyes. To our knowl-edge, this is the first longitudinal study to analyze CCTbefore and after congenital cataract extraction and toevaluate the role of IOL implantation on CCT in pedi-atric cataract surgery.

PATIENTS AND METHODS

All congenital cataract cases consecutively scheduled for sur-gery at Labbafinejad Medical Center between January 2008and September 2009 were enrolled in this prospective study.

0886-3350/$ - see front matter 2041doi:10.1016/j.jcrs.2010.07.016

2042 CCT CHANGES AFTER CONGENITAL CATARACT SURGERY

Normal eyes of children who had general anesthesia for uro-logical procedures at the same center were recruited as a con-trol group. An institutional review board reviewed andapproved the study protocol.

Inclusion criteria were congenital or developmental cata-ract severe enough to decrease the red reflex to less thanthree tenths and significant blocking of the visual axis. Exclu-sion criteria were ocular pathology other than congenital cat-aract, including traumatic cataract, pathologic cataract,microphthalmos, glaucoma, corneal opacity, anterior seg-ment dysgenesis, iris coloboma, and accompanying uveitis.All patients had a detailed preoperative evaluation. Visualacuity was assessed using Snellen charts when possible; ifnot, fixation patterns were noted. The red reflex was evalu-ated by direct ophthalmoscopy. Slitlamp biomicroscopyevaluation of the anterior segment was performed preopera-tively in cooperative patients. A retinal examinationwas per-formed by indirect ophthalmoscopy. If media opacity was sosevere that the retina could not be seen, B-scan ultrasonogra-phy was performed. Infants who could not cooperate forexamination were scheduled for examination under generalanesthesia. During general anesthesia, detailed ophthalmicevaluation was done, including IOP measurement witha Tono-Pen (Reichert). Tonometry was performed no longerthan 5 minutes after induction of anesthesia. The CCT wasmeasured with an ultrasonic pachymeter (PachymeterSP-2000, Tomey Corp.) soon after induction of anesthesia.The pachymeter probe was placed lightly on the center ofthe cornea 3 times. At each contact, the CCT was measured10 times automatically (auto mode). The instrumentautomatically calculated the mean measurement. Duringthe procedure, the cornea was moistened frequently witha balanced salt solution to ensure it was adequatelyhydrated. The same examiner (A.F.) performed all CCTmeasurements.

Based on the findings of the examination under generalanesthesia, if cataract extraction was indicated, patientshad surgery at the same session. The IOL power was calcu-lated using the SRK/T formula based on the keratometry(K) reading and axial length. When keratometry could notbe performed, the standard K reading for the patient’s agewas used.11 To prevent a postoperative myopic shift, a 10%reduction in IOL powerwas considered for children youngerthan 5 years. A 3-piece foldable acrylic posterior chamberIOL with poly(methyl methacrylate) haptics (AcrySof

Submitted: April 27, 2010.Final revision submitted: July 6, 2010.Accepted: July 10, 2010.

From the Ophthalmic Research Center (Faramarzi, Javadi, Bonyadi),Labbafinejad Medical Center, Shahid Beheshti University of MedicalSciences, and the Department of Epidemiology and Biostatics(Yaseri), School of Public Health, Tehran University of MedicalSciences, Tehran, Iran.

Supported by the Ophthalmic Research Center, Shahid BeheshtiMedical University, Tehran, Iran.

Corresponding author: Amir Faramarzi, MD, Ophthalmic ResearchCenter, Labbafinejad Medical Center, Pasdaran Avenue Boostan 9Street, Tehran 1666694516, Iran E-mail: amirfaramarzy@yahoo.com.

J CATARACT REFRACT SURG - V

MA60BM, Alcon, Inc.) was implanted in pseudophakiceyes. If the patient had bilateral cataract and was youngerthan 6 months, an IOL was not implanted. In cases of unilat-eral cataract, an IOL was implanted in infants older than2 months. In these cases, the nonoperated fellow eye wasconsidered a control for the operated eye. Bilateral casesdid not have simultaneous surgery; the second eye wasoperated on no more than 1 month after the first eye.

Surgical Technique

The same experienced surgeon (A.F.) performed all proce-dures using general anesthesia. Preoperative pupil dilationwas achieved by tropicamide 1% eyedrops. After the neces-sary limbal incisions were made and the anterior chamberwas deepened with hydroxypropyl methylcellulose 2%,a forceps-assisted anterior capsulorhexis was created. Ade-quate hydrodissection and manual lens aspiration witha Simcoe irrigation/aspiration system were performed. Aposterior continuous curvilinear capsulorhexis was initiatedwith a 27-gauge cystotome and completed with a capsulo-rhexis forceps. A 2-port central anterior vitrectomy wasperformed through 2 limbal paracenteses. Machine parame-ters included a cut rate of 600 cuts/min and vacuum of100 mm Hg.

If the eye was a candidate for IOL implantation, the IOLwas placed in the ciliary sulcus. Then, the optic was capturedthrough the posterior capsulorhexis with a second instru-ment (sealed-bag technique12). After meticulous irrigationof the anterior chamber, the incisions were closed with10-0 nylon. At the end of surgery, all eyes received a subcon-junctival injection of 100 mg of cephazolin, 2 mg ofdexamethasone, and a sub-Tenon injection of 20 mg methyl-prednisolone acetate.

Postoperative Treatment

Postoperative treatment included betamethasone eye-drops 6 times a day, tapered over 6 weeks, and chloram-phenicol eyedrops 4 times a day for 1 week. Postoperativedilation was achieved intermittently using tropicamide 1%to prevent synechiae formation. Patients were examinedpostoperatively at 1 and 2 days, 1 and 2 weeks, and 1, 3,and 6 months. Each visit included visual acuity, slitlamp bi-omicroscopy evaluation, and IOPmeasurementwith a Tono-Pen when possible. One month and 6 months after surgery,the CCT was measured. In patients unable to cooperate, themeasurement was performed using general anesthesia;the evaluation also included a detailed ophthalmic examina-tion including refraction, suture removal, and IOP measure-ment with a Tono-Pen. The method of CCT measurementwas the same as the technique used before surgery.

Statistical Analysis

Descriptive statistical results are presented as the mean,standard deviation, and minimum and maximum values.Paired t tests were used to analyze the differences betweeneach pair of measurements. A P value less than 0.05 was con-sidered statistically significant.

RESULTS

The study enrolled 47 eyes of 30 patients; 19 patients(63.3%) were boys. Seventeen patients had bilateral

OL 36, DECEMBER 2010

Table 1. Baseline descriptive statistics by group.

Group

VariablePseudophakic

(n Z 32)Aphakic(n Z 15)

Control(n Z 51) P Value

Age (mo) !.001Mean G SD 37.7 G 26.9 5.6 G 6.1 29.1 G 25.6Range 2–102 1–28 1–96

Right eye/left eye (n) 16/16 8/7 26/25 O.999Bilateral/monolateral (n) 11/10 6/3 25/1 d

Mean CCT (mm) G SD 540 G 34 548 G 61 558 G 36 .207

CCT Z central corneal thickness

2043CCT CHANGES AFTER CONGENITAL CATARACT SURGERY

congenital cataract; in these cases, both eyes were en-tered in the study. Table 1 showsbaseline characteristicsof 32 pseudophakic eyes of 21 patients, 15 aphakic eyesof 9 patients, and 51 normal eyes of 26 patients (controlgroup). There was no significant difference in the meanbaseline CCT between the 3 groups (PZ .207).

Table 2 shows the preoperative and postoperativemean CCT values in the aphakic group and pseudo-phakic group and the statistical analysis results ineach group and between the pseudophakic groupand the aphakic group. The difference between the 2groups in themean CCT at the 1-month follow-up visitwas statistically significant (P Z .018). This differencewas greater after adjustment of the 1-month CCTvalues for baseline CCT values (P!.001). The differ-ence between the 2 groups at 6 months was also statis-tically significant (P Z .012) (Figures 1 and 2). Thisdifference was greater after adjustment of the 6-monthCCT values for baseline CCT values (P!.001). After

Table 2. Preoperative and postoperative mean CCT values in the aphakeach group and between the 2 groups.

Time

Mean (mm) G SD

PseudophakicGroup (n Z 32)

AphakicGroup (n Z 15)

Baseline 540 G 34 548 G 61Postoperative

1 MonthCCT 539 G 37 587 G 65Change 2 G 17 �38 G 30P value, within* .463 !.001

6 MonthsCCT 540 G 36 602 G 65Change 0 G 18 �50 G 31P value, within* 1.0 !.001

CI Z confidence interval; CCT Z central corneal thickness; GEE Z generalized es*Based on paired t test†Adjusted for baseline values and age (based on GEE)

J CATARACT REFRACT SURG - V

the 2 groups were adjusted for age and preoperativeCCT values, the differences remained significant at 1month and 6 months (P!.001) (Table 2).

In the pseudophakic group, there was no significantdifference between the 1-month and 6-month postop-erative CCT values and the baseline measurements(P Z .463 and P Z 1.00, respectively). In the aphakicgroup, however, both differences were statisticallysignificant (P!.001) (Table 2).

Table 3 shows baseline and follow-up data compar-ing the 10 unilateral pseudophakic eyes and thenonoperated fellow eyes (controls). There was no sig-nificant difference in the mean CCT measurementsbetween the 2 subgroups at any time.

The mean preoperative IOP was 15 G 5.6 mm Hg inthe pseudophakic group and 14.1 G 4.6 mm Hg in theaphakicgroup (PZ .51).Themean IOP6monthspostop-erativelywas 14.5G 4.2mmHg and 15.2G 3.3mmHg,respectively (P Z .39). There was no significant

ic group and pseudophakic group and statistical analysis results in

Mean Difference(95% CI)

P Value

Based onGEE Adjusted†

�8 (�36 to 19) .831 d

�48 (�78 to �18) .018 !.00136 (21 to 52) !.001 d

d d d

�62 (�92 to �33) .012 !.0017 (4 to 10) !.001 d

d d d

timating equation

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Figure 1. Mean and 95% CI of CCT in aphakic eyes and pseudo-phakic eyes at baseline and postoperatively at 1month and 6months(CCT Z central corneal thickness; CI Z confidence interval).

Figure 2.Meanand95%CIofCCTchanges in aphakic eyes andpseu-dophakic eyes at baseline and postoperatively at 1 month and6months (CCTZ central corneal thickness;CIZ confidence interval).

2044 CCT CHANGES AFTER CONGENITAL CATARACT SURGERY

difference in themean preoperative or 6-month postop-erative IOP within the aphakic group or within thepseudophakicgroup (PZ .58 andPZ .74, respectively).

There were no significant intraoperative complica-tions. During short-term follow-up, there were 3 casesof postoperative inflammation in the pseudophakicgroup and 2 cases in the aphakic group. All cases

Table 3. Intrasubject analysis of preoperative and postoperative mean C

Mean G SD

Time

PseudophakicGroup(n Z 10)

ControGroup(n Z 10

Baseline 541 G 37 540 G 3Postoperative

1 MonthCCT (mm) 534 G 26 545 G 2Change (mm) 19 G 22 8 G 1Change (%) 3 G 4 1 G 2P value, within* .142 .171

6 MonthsCCT (mm) 544 G 40 551 G 3Change (mm) 4 G 12 �2 G 8Change (%) 1 G 2 0 G 1P value, within* .192 .405

CI Z confidence interval; CCT Z central corneal thickness*Based on paired t test†Adjusted for baseline based on generalized estimating equation

J CATARACT REFRACT SURG - V

resolved after the frequency of the steroid eyedropswas increased. Three cases of capsule phimosisoccurred in the pseudophakic group; in 1 case, thevisual axis was occluded and surgical membranec-tomy was performed 8 months after cataract surgery.There were no cases of aphakic or pseudophakicglaucoma during the 6-month follow-up.

CT measurements in unilateral pseudophakic eyes.

l

)Mean Paired Difference

(95% CI) P Value†

8 1 (�12 to 14) .895

2 �11 (�33 to 11) .2401 10 (�7 to 27) .163

2 (�1 to 5) .164d d

9 �7 (�18 to 4) .1796 (�5 to 17) .2191 (�1 to 3) .221

d d

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2045CCT CHANGES AFTER CONGENITAL CATARACT SURGERY

DISCUSSION

Although there are many reports of increased CCTafter the removal of congenital cataracts,1–5 none com-pared the CCT values before cataract removal with thepostoperative values. Lupinacci et al.4 measured theCCT in eyes with congenital cataracts and surgicalaphakia. They found that aphakic eyes due to conge-nital cataract extraction had thicker corneas thannormal phakic eyes and suggest that the increasein CCT occurs postoperatively. They included nopseudophakic eyes in their study.

Muir et al.1 found that the CCT was similar in eyeswith pediatric cataract and in normal control eyesand that the CCT increased after cataract surgery.However, in their study, the mean CCT in aphakiceyeswas greater than in the control eyes, eyeswith cat-aract, and eyes with pseudophakia. The authors didnot mention the percentage of primary and secondarypseudophakia.

Simsek et al.2 compared 43 eyes of 43 aphakic andpseudophakic patients after congenital cataract sur-gery with eyes of 44 healthy age- and sex-matched vol-unteers. The mean CCT values of the aphakic eyeswere significantly greater than in the pseudophakiceyes, in which an IOL had been implanted at thetime of congenital cataract surgery. Differencesbetween aphakic eyes and pseudophakic eyes inwhich an IOL had been implanted secondarily werenot significant. Only 10 eyes in their study werepseudophakic, and primary IOL implantation wasperformed in 5 cases.

Simon et al.3 describe increased CCT in aphakic/pseudophakic children compared with controlpatients. In their series, only 2 primary pseudophakiapatients were included.

Nilforushan et al.5 report that the corneas in eyeswith extracted congenital cataract were significantlythicker than in normal control eyes. They found no sig-nificant difference in the corneal endothelial cell countor morphology between operated eyes and normaleyes. They dismissed endothelial damage as a possibleexplanation for the increase in CCT after congenitalcataract surgery. The authors propose that eyes withcongenital cataract have thicker corneas preopera-tively. This differs from our findings.

All previous studies of the change in CCT aftercongenital cataract surgery compared the CCT inaphakic/pseudophakic eyes and control eyes; nonehad access to preoperative CCT values. We believeours is the first longitudinal study of CCT changes inpatients who had congenital cataract extraction.

In the current study, the mean CCT in the normaleyes was 558 G 36 mm, similar to values reportedby Hossein et al.13 (549 G 46 mm) and Dai et al.14

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(563G 36 mm). We found that the CCT before surgeryin eyes with congenital cataract was similar to that innormal eyes and that there was an increase in CCTpostoperatively in aphakic eyes but not in pseudo-phakic eyes. Themechanism of CCT increase after con-genital cataract extraction remains a matter ofspeculation. In normal eyes without cataract, the cen-tral cornea is thicker at birth, rapidly decreases inthickness during the first few months of life, andthen stabilizes over time.13 This change in cornealthickness occurring in the first months of life indicatesthat corneal development continues after birth. Devel-opment of the cornea is affected by the crystalline lensduring the embryological period.15 This effect maycontinue after birth, and removing the crystallinelens at an early age may stop it. We speculate thatthe crystalline lens acts as a barrier because substitu-tion of the natural lens with an IOL in pediatric cata-ract surgery had no effect on CCT in our study.

Another theory of the increase in CCT after pediatriccataract surgery is endothelial cell damage at the timeof surgery.3,5 Mechanical stress to endothelial cellswith unrecognized surgical trauma and irrigationfluids has been proposed as a cause of endothelialcell dysfunction and increased CCT after pediatric cat-aract surgery. Increased CCTwas seen in aphakic eyesbut not in pseudophakic eyes in our study. Thus, it isless probable that the increase is due to mechanicalstress during cataract surgery because theoretically,endothelial cell trauma would be greater in pseudo-phakic eyes than in aphakic eyes.

There are several reports that primary pseudophakiamay be associated with a lower rate of glaucoma fol-lowing surgery for congenital cataract.16–19 It has beensuggested that exposure of maturing angle structuresto thepotentiallyharmful effect of vitreous componentsis a possible factor in developing aphakic glaucoma,and access to the trabecular meshwork is preventedor minimized in the pseudophakic eye by the presenceof the IOL.10,16 This finding is a key component of ourtheory about the barrier effect of the IOL in preventingincreased CCT after pediatric cataract surgery.

Some authors believe that surgery for congenitalcataract at an early age increases the risk for glaucomawhether the eye is aphakic or pseudophakic.20,21 Therewere no cases of postoperative glaucoma in our series.The mean 6-month postoperative IOP was not greaterthan the mean preoperative IOP in the aphakic group,although the postoperative CCT values in those eyeswas significantly thicker than baseline measurements.Thismay be because all IOP readings in our studywereperformedwithaTono-Pen, and this instrument is leastaffected by CCTwhen used to measure IOP.22,23 Gold-mann applanation tonometry tends to overestimate

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2046 CCT CHANGES AFTER CONGENITAL CATARACT SURGERY

IOP in pediatric eyes with a thick cornea,10 leading tounnecessary prescription of antiglaucoma medica-tions. Absence of postoperative glaucoma in our seriescan be attributed to the relatively short follow-up,primary PC IOL implantation in the majority of caseswith haptics in the ciliary sulcus instead of in thecapsular bag, and surgery at an older age (mean 37.7months, pseudophakic group; 5.6 months, aphakicgroup).

It was impossible to age match aphakic eyes withpseudophakic eyes in our study because of the limita-tion of IOL implantation in very young infants;however, we evaluated the role of age by comparingpatients of the same age in the 2 groups. After adjust-ment for age, the mean CCT was significantly greaterin the aphakic group than in the pseudophakic group 1month and 6 months postoperatively (P!.001). Basedon these findings, we believe that regardless of patientage, primary pseudophakia has a protective roleagainst increased CCT after pediatric cataract surgery.

Several factors control corneal hydration and there-fore corneal thickness; these include evaporation, IOP,swelling pressure, endothelial permeability, endothe-lial fluid pump, endothelial pump rate receptors, andcorneal epithelium.24 Our study could not clearly ad-dress the reasons for increased CCT in the eyes leftaphakic after congenital cataract surgery. Evaluationof the corneal layers’ anatomy and function in eyeswith congenital cataract before and after cataractextractionwould help elucidate the underlying causes.

Our findings are from the first 6 months postopera-tively. The results, especially in pseudophakic eyes,may change with a longer follow-up. Another limita-tion is the small number of patients, especially in theaphakic group, which makes it difficult to generalizethe results with certainty.

In conclusion, IOP measurement is the most impor-tant factor in the diagnosis of glaucoma in children.Therefore, increased corneal thickness in aphakiceyes after cataract extraction and its effect on IOPmea-surement must be kept in mind. We showed that theCCT increases after surgery and that IOL implantationmay have a protective effect. We speculate thatvitreous factors could have an important effect onthe maturing cornea and that IOL implantation afterpediatric cataract surgery appears to protect thecornea against these unknown factors.

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36, DECEMBER 2010

First author:Amir Faramarzi, MD

Ophthalmic Research Center,Labbafinejad Medical Center, ShahidBeheshti University of MedicalSciences, Tehran, Iran