Infantile cataracts

Visual outcome in patients with isolated autosomal dominant congenital cataract

OBJECTIVE

To determine the visual outcome and surgical complication rates of patients with isolated inherited congenital cataract.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

Patients and their families were ascertained from the genetic eye clinic and outpatient databases of Moorfields Eye Hospital, London, and invited to participate in the study. Four hundred twenty-two individuals from 72 pedigrees with this form of autosomal dominant cataract underwent ophthalmologic assessment.

MAIN OUTCOME MEASURES

Visual acuity and surgical complications (glaucoma, retinal detachment, amblyopia).

RESULTS

In this study 49.4% of patients (46.8% of those operated) achieved a visual acuity (VA) of 20/40 or better, 35.9% (36.1% of those operated) a VA between 20/50 and 20/200, and 14.7% (17.1% of those operated) worse than 20/200. Opacities that were more diffuse or did not lie close to the visual axis were associated with a better prognosis for vision; 6.6% had glaucoma and 5.0% had retinal detachment develop.

CONCLUSIONS

Patients with isolated inherited congenital cataract have a better visual and surgical outcome than those with coexisting ocular and systemic abnormalities. The improved prognosis is related in part to the lack of other developmental abnormalities of the eye, and, because inherited cataracts are often partial at birth, surgery may be delayed to later infancy and childhood when there is a lower incidence of surgical complications and refractive correction is easier. Certain inherited phenotypes (lamellar, pulverulent, polymorphic, coralliform, and cortical) also seem to have a better prognosis, and this should be borne in mind when counseling these families. A large number of the patients in this study underwent surgery many years previously, when surgical outcomes were less favorable, and thus the results of this study establish only a minimum acuity dataset for the purposes of counseling.

A comparison of grating visual acuity, strabismus, and reoperation outcomes among children with aphakia and pseudophakia after unilateral cataract surgery during the first six months of life

PURPOSE

The method of correcting aphakia after unilateral cataract extraction during infancy is controversial. Some authorities advocate correction with an intraocular lens (IOL) whereas others advocate correction with a contact lens (CL). We compared grating visual acuity, alignment, and reoperative outcomes in age-matched children treated with these 2 modalities at 5 clinical centers.

METHODS

Twenty-five infants born in 1997 or 1998 with a dense unilateral congenital cataract who had cataract surgery coupled with (IOL group, n = 12) or without (CL group, n = 13) primary IOL implantation were enrolled in this study. All patients were prescribed half-time occlusion therapy. In July 1999, their grating visual acuities, ocular alignments, and reoperation rates were assessed.

RESULTS

The mean grating visual acuity (LogMAR) for the affected eye was 0.70 +/- 0.32 for the IOL group and 0.87 +/- 0.31 for the CL group (P =.19). The mean interocular difference in grating visual acuity was 0.26 +/- 0.30 for the IOL group and 0.50 +/- 0.28 for the CL group (P =.048). The incidence of strabismus (>10 PD) was 75% in the IOL group compared with 92% in the CL group (P =.24). The incidence of reoperations was 83% in the IOL group compared with 23% in the CL group (P =.003).

CONCLUSIONS

Our preliminary data suggest that correcting aphakia after unilateral congenital cataract surgery with primary IOL implantation results in an improved visual outcome but a higher rate of complications requiring reoperation. A randomized clinical trial, the Infant Aphakia Treatment Study, is planned to further study the optimal treatment for aphakia following unilateral cataract extraction during infancy.

Visual outcome and complications of bilateral intraocular lens implantation in children

PURPOSE

To determine the safety and efficacy of bilateral intraocular lens (IOL) implantation in children.

SETTING

Tertiary referral pediatric ophthalmology department.

METHODS

This retrospective study comprised 13 children (26 eyes) who had bilateral cataract surgery with IOL implantation. Patients were divided into 2 groups: congenital cases, diagnosed during the first year of life, and developmental cases, diagnosed after 1 year of age. All patients had small incision phacoemulsification with primary implantation of a poly(methyl methacrylate) or a foldable acrylic IOL. Primary posterior capsulotomy was performed in 16 eyes (61.5%).

RESULTS

Age at surgery ranged from 1 week to just under 8 years. Seven patients (53.8%) had a systemic diagnosis: Down's syndrome (n = 4); developmental delay or cerebral atrophy (n = 3). Five children with systemic problems could not cooperate with formal vision testing; 2 could fix and follow bilaterally, and 3 had central, steady, and maintained vision bilaterally. In the congenital group, 37.5% of eyes attained a visual acuity of 20/20 and 87.5%, 20/120 or better. In the developmental group, formal vision testing was possible in 4 children. Five eyes (83.3%) attained a visual acuity of 20/40 or better. Thirteen eyes (50.0%) required posterior capsulotomy. Primary posterior capsulotomy reduced the incidence of posterior capsule opacification (PCO), but there was no correlation between PCO and IOL material. One patient developed glaucoma bilaterally.

CONCLUSION

Bilateral IOL implantation was safe and produced good visual results in children of all ages with bilateral cataract.

Primary posterior capsulorhexis with optic capture and intracameral heparin in paediatric cataract surgery

PURPOSE

To study the efficacy of using a primary posterior capsulorhexis with optic capture and intracameral heparin in preventing secondary posterior capsule opacification, in paediatric cataract surgery.

METHODS

Primary posterior capsulorhexis and optic capture with a heparin-coated intraocular lens (IOL) was performed after lens aspiration in 14 cataractous eyes of 13 children (group I). Ten international units of heparin were added in the irrigating solution. The results were compared with 14 eyes of 11 children who underwent a similar surgical procedure but without a posterior capsulorhexis (group 2).

RESULTS

The mean age of the patients in group I was 4.2+/-1.5 years (mean +/- SD) and in group 2 was 4.5+/-1.8 years (range 3-6 years in both the groups). The mean duration of follow up was 36+/-6.4 months in group I and 38+/-8.1 months in group 2. A best corrected visual acuity of 6/24 or better was achieved in 12 eyes in group I and II eyes in group 2. The visual axis remained clear in all the eyes in group I, while 8 eyes (57.14%) in group 2 developed posterior capsule opacification (P = 0.0034) which required a neodymium:yttrium-aluminum-garnet laser capsulotomy.

CONCLUSIONS

Lens aspiration using intracameral heparin, combined with primary posterior capsulorhexis and optic capture of a heparin-coated IOL, is a useful technique to prevent secondary visual axis opacification in paediatric cataracts.

High levels of binocular function are achievable after removal of monocular cataracts in children before 8 years of age

OBJECTIVE

To investigate the visual acuity and binocular function results achieved in children who had monocular cataracts removed before 8 years of age.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Clinical records of 171 patients who underwent a unilateral cataract removal between January 1986 and 1996 were reviewed retrospectively. Seventy-four eyes were included in the study: 19 congenital, 11 developmental, 19 posterior lenticonus, 19 traumatic, and 6 complicated cataracts. Patients with less than 2 years of follow-up; eyes with cataracts resulting from retinoblastoma; prematurity; and those associated with dense corneal scars, lens dislocation, and persistent hyperplastic primary vitreous were excluded.

INTERVENTION

Visual acuity was measured by means of age-appropriate tests such as the fixation pattern, Allen object recognition cards, isolated optotypes with the Sheridan Gardiner test, and Snellen letters. Sensory fusion was assessed with the Worth 4-dot test, and stereo acuity was assessed with the Titmus stereo test.

MAIN OUTCOME MEASURES

Cataracts were classified regarding type, extent, age at onset, duration of the opacity, age at surgery, method of removal, development of secondary membrane, form of optical rehabilitation, and presence of strabismus. Visual acuity levels between 6/6 and 6/12 were considered "good." Fusion of the Worth 4-dot test at distance and near, and presence of stereo acuity of 100 seconds of arc or better were considered "good" binocular function. Multiple logistic regression analysis was used to define factors that correlated with achieving good visual outcome.

RESULTS

Visual acuity was 6/12 or better in 27 (36.5%) eyes. However, good binocular function was achieved in only 11 of these 27 patients. Results of univariate analysis showed that later age at onset of cataract and absence of strabismus were significant for good visual acuity and binocular function. The presence of strabismus increases the risk of not achieving good visual acuity by 5.45-fold.

CONCLUSIONS

Good visual acuity and binocular function can be achieved after removal of monocular cataracts in visually immature children. Patients with strabismus at presentation or during the follow-up period have the least chance of achieving a good sensory result.

Surgical management of congenital cataract associated with severe microphthalmos

PURPOSE

To report the results of cataract surgery in children with severe microphthalmos and congenital cataract.

SETTING

Seoul National University, Department of Ophthalmology, Seoul, Korea.

METHODS

Retrospective studies were conducted by reviewing the charts of 20 eyes of 11 patients with severe microcornea and microphthalmos or severe microcornea with a corneal diameter smaller than 9.0 mm. The patient pool was divided according to surgical method, specifically by incision site: an anterior group that had corneal limbal incisions and a posterior group treated via pars plicata incisions. Preoperative examinations included bilaterality, corneal diameter, axial length, and eye and systemic abnormalities. Postoperative results and complications of the 2 operative methods were compared.

RESULTS

All 11 patients had bilateral congenital cataract and microphthalmos. Except in 1 case, surgeries were done in patients ranging in age from 2 to 16 months. Mean follow-up was 2 years. Corneal diameter was smaller than 9.0 mm in all 20 eyes and smaller than 7.5 mm in 11 eyes. Ten eyes were categorized into the anterior group, and the other 10 eyes were placed in the posterior group. Postoperative complications included secondary membranes in 3 eyes in the posterior group and corneal opacity in 3 eyes in the anterior group.

CONCLUSION

The surgical management of children with congenital cataract and severe microphthalmos is recommended as a way to improve vision but must be performed carefully to avoid complications.

The genetics of childhood cataract

Human congenital cataract has a diverse aetiology. In the proportion of cases where the cause is genetic, the disease shows wide phenotypic and genetic heterogeneity. Over the past few years, much research has been devoted to mapping the genes that underlie the disorder. This has been helped by the extensive array of naturally occurring and genetically engineered mouse cataract models and the abundance of human candidate genes. Most progress to date has been in the identification of genetic mutations causing autosomal dominant congenital cataract where eight genes have been implicated in cataractogenesis. Overall there is good correlation between the genetic mutations so far identified and the resulting lens phenotype but it is clear that mutations at more that one locus may give rise to similar forms of cataract. The identification of genes causing inherited forms of cataract will improve our understanding of the mechanisms underlying cataractogenesis in childhood and provide further insights into normal lens development and physiology. Perhaps more importantly, it is likely that some of the genes causing early onset cataract will be implicated in age related cataract which remains the commonest cause of blindness in the world.

Clinical symptoms and visual outcome in patients with presumed congenital cataract

PURPOSE

To investigate clinical symptoms and visual outcome in patients who had presumed congenital cataract with visual acuity > or =20/200.

METHODS

Twenty-nine patients (50 eyes) ranging in age from 5-28 years were included in this study. Congenital cataract was diagnosed by patients' past history, previous medical records, and typical findings of congenital cataract. Inclusion criteria were patients with visual acuity measured by Snellen chart, best corrected visual acuity > or =20/200, and no eye or systemic diseases influencing visual acuity. Seven patients had unilateral cataracts and 22 patients had bilateral cataracts. Cataracts were nuclear in 29 eyes, anterior or posterior subcapsular in 12 eyes, and polar in 7 eyes. All patients underwent lens aspiration or phacoemulsification combined with posterior chamber intraocular lens (PC-IOL) implantation without performing intentional posterior capsulotomy and anterior vitrectomy.

RESULTS

The most common clinical symptom was visual disturbance followed by blurred vision, glare and knitting the brow, strabismus, and leukocoria. Comparison of calculated PC-IOL power showed a more significant myopic shift in unilateral cataract than in bilateral cataract. Postoperative best corrected visual acuity >20/25 was attained in 28 (65.1%) eyes with bilateral cataracts and 1 (14.3%) eye with a unilateral cataract.

CONCLUSIONS

Cataract surgery is effective not only in improving visual acuity but also in eliminating clinical symptoms. Delaying cataract surgery in early infancy should be considered to avoid intentional operative procedures in patients with bilateral congenital cataract preserving visual acuity >20/200.

Cataract and phthisis bulbi after laser photoablation for threshold retinopathy of prematurity

PURPOSE

To describe the visual and structural outcome of eyes that developed a dense cataract after laser photoablation for threshold retinopathy of prematurity.

METHODS

A retrospective review of eight consecutive infants who developed dense cataract(s) after bilateral laser photoablation for threshold retinopathy of prematurity. Of the 10 eyes with cataract, five eyes were treated with a diode laser and five with an argon laser. The stage and zone of the retinopathy of prematurity, number of burns applied, time of onset of the cataract, clinical findings at the time of cataract surgery, and the course after cataract surgery were reviewed.

RESULTS

Six eyes had zone 1 disease and four had zone 2 disease. The mean number of burns applied per eye was 2532 +/- 856 (range, 1400 to 4500). A cataract was diagnosed a median of 3 [corrected] weeks (range, 1 to 28 weeks) after laser photoablation. Nine of the 10 cataracts were sufficiently dense to preclude a view of the fundus. All 10 eyes had clinical signs suggestive of an inflammatory or ischemic process that included one or more of the following findings: corneal edema, pupillary membrane, iris atrophy, depigmentation of ciliary processes, pigment on the anterior lens surface, posterior synechiae, hyphema, and shallow anterior chamber. Nine eyes underwent cataract surgery. Five of the 10 eyes had retinal detachment ranging in severity from stage 4A to stage 5 at the time of cataract surgery. Nine of the 10 eyes progressed to phthisis bulbi and no light perception.

CONCLUSIONS

A dense cataract developing in the eye of an infant after laser photoablation for threshold retinopathy of prematurity is associated with a poor visual prognosis. The constellation of associated clinical findings appears to be most consistent with anterior segment ischemia.

Missense mutations in MIP underlie autosomal dominant 'polymorphic' and lamellar cataracts linked to 12q

Human inherited cataract is both clinically diverse and genetically heterogeneous. Here we report the identification of the first mutations affecting the major intrinsic protein of the lens, MIP, encoded by the gene MIP on 12q14. MIP is a member of the aquaporin family of membrane-bound water channels. The mutations identified are predicted to disturb water flux across the lens cell membrane.

Intercellular communication in the eye: clarifying the need for connexin diversity

In the vertebrate eye, virtually every cell type is directly coupled to its neighbors by intercellular channels present in gap junctions. Although these structures share the common property of allowing adjacent cells to directly exchange ions, second messengers and small metabolites, intercellular channels in the eye also play a specific role in distinct functions such as neuronal transmission at electrotonic synapses in the retina, and the maintenance of homeostasis in the avascular lens. The structural proteins comprising these channels, the connexins (Cx), are a multigene family of which many members are expressed in the eye, even in the same cell type. This molecular heterogeneity poses the crucial question of whether and how a diversity in gap junctional structural proteins influences intercellular communication in ocular tissues. This review will focus on two recent advances in the understanding of connexin diversity in regard to the eye. First, connexin knockouts have demonstrated that postnatal development and homeostasis in the lens requires multiple connexin proteins. Secondly, functional characterization of new connexins that are abundantly expressed in the retina has revealed biophysical properties that mimic those recorded from retinal neurons.

Linkage analysis in an autosomal dominant 'zonular nuclear pulverulent' congenital cataract, mapped to chromosome 13q11-13

PURPOSE

To determine by linkage analysis the chromosomal locus responsible for autosomal dominant congenital cataract (ADCC) in a four-generation Welsh pedigree.

METHODS

The family pedigree was traced through two members of the family attending the hospital for treatment of their cataracts. Twenty-five members of the family were examined ophthalmologically and blood was collected with consent for genetic linkage analysis.

RESULTS

Fifteen members of this family were known to have bilateral congenital cataracts, of whom 11 had a cataract extraction prior to examination. The youngest member of the pedigree was 5 years old and the oldest was 78 years old. Four children, unoperated at the time of this study, had a phenotypically identical morphology of their zonular pulverulent congenital cataracts. The known loci for congenital cataract were excluded. Significant lod scores for markers in the 13q11-13 region were detected with a Zmax of 3.59 D13S1236 (theta = 0.00).

CONCLUSIONS

We report linkage of an ADCC of the zonular pulverulent type to chromosome 13q11-13 in a four-generation family.

Genetically distinct autosomal dominant posterior polar cataract in a four-generation Japanese family

PURPOSE

To describe the clinical findings of a form of posterior polar cataract in a large Japanese family and to determine whether the posterior polar cataract is causally related to other autosomal dominant cataracts with known genes, chromosomal locations, or both.

METHODS

Systemic and ocular histories were obtained and comprehensive ophthalmic examinations were performed in 15 of 37 members of the Japanese family. The posterior polar cataract was transmitted in an autosomal dominant manner through four generations. Although there is some variation in the degree of opacification, the posterior polar cataract in this family is characterized by progressive disk-shaped posterior subcapsular opacities. Genetic linkage analysis was performed with 41 polymorphic microsatellite markers located in chromosomal regions known for linkage to cataracts. Genomic DNA extracted from the 15 individuals was amplified by polymerase chain reaction, the genotype at the marker loci was determined in each family member, and the lod score was calculated at each locus.

RESULTS

Significant linkage of the posterior polar cataract was ruled out from the following 10 loci or chromosomal regions: 16q22 and 1p36, to which two forms of autosomal dominant posterior polar cataract have been assigned: 1q21-q25, 2q33-q35, 13cen, 17p13, 17q11-q12, 17q24, 21q22, and 22q, which are the regions responsible for other autosomal dominant congenital cataracts.

CONCLUSIONS

This study confirms the genetic heterogeneity of autosomal dominant posterior polar cataracts and demonstrates that the posterior polar cataract in this Japanese family is phenotypically and genetically distinct from previously mapped cataracts.

Visual results and postoperative complications of capsular bag and ciliary sulcus fixation of posterior chamber intraocular lenses in children with traumatic cataracts

PURPOSE

To evaluate the visual results and postoperative complications of capsular bag and ciliary sulcus fixation of posterior chamber intraocular lenses (IOLs) for traumatic cataracts in children.

SETTING

Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

METHODS

Twenty children (20 eyes) with traumatic cataracts had extracapsular cataract extraction (ECCE) and posterior chamber IOL implantation. They were randomly divided into 2 groups. Capsular bag fixation was performed in 10 children (Group A) and ciliary sulcus fixation in the other 10 (Group B). Traumatic cataracts associated with large corneal lacerations (10.0 mm or more), hyphema, angle recession, or posterior segment involvement were excluded. The best corrected visual acuity (BCVA) as well as early and delayed postoperative complications were prospectively evaluated in both groups.

RESULTS

The BCVA was 6/12 or better in 9 eyes (90%) in Group A and 8 eyes (80%) in Group B at the end of the mean follow-up (24.6 months +/- 10.6 [SD]). Amblyopia (1 eye in Group A) and corneal scar and commotio retinae (1 eye each in Group B) accounted for a visual acuity of worse than 6/12. The residual refractive error did not exceed 3.50 diopters in either group. The incidences of fibrinous anterior uveitis and pupillary capture were significantly higher in Group B (P < .05, Fisher exact test).

CONCLUSION

Capsular bag fixation of posterior chamber IOLs provided visual results similar to those with ciliary sulcus fixation but was associated with fewer postoperative complications, particularly uveitis and pupillary capture. This represents another important reason to attempt in-the-bag fixation in cases of traumatic cataract.

Unilateral intraocular lens implantation during the first six months of life

PURPOSE

The purpose of this study was to determine the incidence of postoperative complications and the occurrence of myopic shift in infantile eyes after cataract surgery and implantation of an intraocular lens (IOL).

METHODS

Cataract surgery and IOL implantation was performed on 11 infants with unilateral congenital cataracts who had a mean age of 10+/-6 weeks at 5 clinical centers. IOLs with a mean power of 26.2+/-2.3 D were implanted using a standardized protocol. The infants were then followed up for a mean of 13+/-6 months for postoperative complications and longitudinal changes in their refractive error.

RESULTS

Eight of the 11 eyes had postoperative complications and were treated with a reoperation. Complications included open-angle glaucoma (n = 2), lens reproliferation into the visual axis (n = 2), pupillary membranes (n = 2), and corectopia (n = 2). A younger age at the time of surgery was positively correlated with the development of a postoperative complication requiring a reoperation (P = .03). A mean myopic shift of 5.49 D occurred in these eyes a year after surgery. No preoperative factors could be identified that correlated with the magnitude of the myopic shift.

CONCLUSION

IOL implantation during infancy is associated with a high complication rate frequently requiring reoperation. A large myopic shift typically occurs that necessitates an initial or a late overcorrection with spectacles or a contact lens, depending on the power of the IOL implanted. Until ongoing randomized trials are completed, we recommend that surgeons exercise caution before implanting IOLs in the eyes of infants.

Genetic and segregation analysis of congenital cataract in the Indian population

Congenital cataract is a major cause of blindness in children, and there is wide variation in the few reports available on the frequencies of its different inheritance patterns. Two hundred and fifty-two families with congenital cataract belonging to 13 different states of India, were clinically and genetically investigated to study their inheritance and segregation patterns. Twenty-one percent of the cases were autosomal recessive, 15% autosomal dominant, 63% were simplex cases, and in the remaining cases the inheritance pattern was not clear. A high incidence of consanguinity (50.9%) was observed in autosomal recessive cases. Out of 340 affected individuals, 222 (65.3%) were males and 118 (34.7%) were females. Segregation analysis showed good agreement in autosomal dominant and recessive families and the data are indicative of the prevalence rate for different inheritance patterns of congenital cataract within the Indian population.

The IOLAB, Inc pediatric intraocular lens study. AAPOS Reasearch Committee. American Association for Pediatric Ophthalmology and Strabismus

PURPOSE

This report is a summary of the data of the IOLAB, Inc pediatric intraocular lens (IOL) implantation investigation. The goal of this study was to evaluate the safety and efficacy of IOL implantation for the treatment of pediatric aphakia, pending approval by the Food and Drug Administration.

METHODS

From May 1981 to July 1994, a total of 1260 pediatric eyes received 171 styles of IOLs implanted by 361 US investigators. Preoperative, operative, and postoperative status reports over the first year were required for each eye entered into the study. Annual visit reports were requested thereafter to determine the long-term effects. The study was terminated in November 1995. All IOLs were obtained from IOLAB, Inc (now Chiron Vision Corp).

RESULTS

Reporting compliance was 98.3% for the preoperative and operative reports, 45.1% at 1 year, and 13.8% at 3 years. The subjects' ages ranged from younger than 1 yearto 17 years. Nine subjects (0.7%) were younger than 1 year, with the largest group of 533 subjects (42.3%) aged between 6 and 12 years atthe time of surgery. Cataract types were congenital (45.6%), traumatic (37.1%), secondary (11%), senile (0.95%), and unrecorded (5.4%). The IOL was implanted primarily in 74.8% of cases and secondarily in 21.4% of cases. There was no record in 3.8% of the cases. IOL types included anterior chamber (4.1%), iridocapsular (0.71%), posterior chamber (93.6%), and unrecorded (1.59%). There were 130 adverse reactions that required secondary surgical intervention. The most frequently performed surgical procedures included lens removal without replacement, vitrectomy, lens repositioning, and lens replacement. More than half (52%) of all eyes had a visual acuity of 20/200 or worse before surgery; amblyopia was reported in 21.1% of all participants at baseline. Postoperative visual acuity data were available on 563 eyes at 1 year after surgery. Overall, 52.8% of all eyes attained a visual acuity of 20/40 or better by the 1-year visit, and only 15.5% had visual acuity worse than 20/200. In general, the older patient, traumatic cataract, and secondary cataract categories were overrepresented in the better visual acuity outcome group.

CONCLUSION

The IOLAB, Inc pediatric IOL study is the first multiple-practitioner, national study designed to evaluate the safety and efficacy of IOL implantation in children. The study results are compromised by the almost 50% loss of follow-up at the 1-year evaluation. Other variables that most likely influenced outcome results were the methods of cataract extraction, medical management, and IOL design, all of which evolved dramatically over the time course of the study. Despite these issues, pediatric IOL implantation seems to be a reasonable treatment modality for aphakia, on the basis of the available 1-year follow-up data of the remaining 45.1% of eyes in the study.

Infantile lensectomy and intraocular lens implantation with long-term follow-up in a monkey model

PURPOSE

To report the long-term clinical and histopathologic findings in infant monkeys following a lensectomy and intraocular lens (IOL) implantation using two different surgical techniques.

METHODS

A lensectomy and IOL implantation was performed on the right eye of 10 infant monkeys. A posterior capsulotomy was performed using a limbal approach in 5 monkeys (Group 1), and a pars plana approach in 5 other monkeys (Group 2). The residual refractive error in the pseudophakic eye was then corrected with a contact lens and the fellow eye was occluded for 70% of the daylight hours. The monkeys were then examined at regular intervals for 2 to 4 years. Visual acuity was assessed using operant testing and sweep visual evoked potentials (VEPs). At the end of the study, the pseudophakic eyes were studied histopathologically.

RESULTS

The only complications that required reoperation were diaphanous fibrin membranes on the lens optic (n=10) and lens reproliferation into the pupillary space (n=5). The visual outcome was similar in Groups 1 and 2, with better acuities in the phakic eyes compared with the pseudophakic eyes. A higher percentage of both haptics were found in the capsular bag for the monkeys in Group 2 (n=3) than in Group 1 (n=1).

CONCLUSIONS

Although haptic placement was superior using a pars plana approach to perform the primary posterior capsulotomy, no clinically discernable difference was noted in IOL centration between the monkeys undergoing a limbal versus a pars plana posterior capsulotomy and no difference was noted in the visual outcome.

Childhood blindness in Uzbekistan

PURPOSE

To elucidate the aetiology of childhood blindness in the Republic of Uzbekistan and to assess the needs for future provision of ophthalmic services for children.

METHODS

Six hundred and seventy-one children in seven schools for the blind and visually impaired throughout Uzbekistan were examined using the WHO/PBL (World Health Organization Prevention Of Blindness) childhood blindness proforma. The locations were chosen to give a representation of the major areas of population within the country.

RESULTS

Of the 671 children examined, 506 (75.4%) were blind or severely visually impaired (corrected visual acuity of less than 6/60 (20/200) in the better eye). Cataract-related blindness (35%), retinal dystrophies (24%) and microphthalmos (23%) formed the three largest diagnostic categories.

CONCLUSIONS

The commonest avoidable cause of blindness was found to be cataract; the cause of poor vision may be due to unoperated cataract, aphakia, amblyopia or post-operative capsular fibrosis. The high proportion of retinal dystrophies may be related to the common practice of consanguineous marriage. The frequent finding of microphthalmos is discussed and compared with findings from other surveys. Glaucoma accounted for approximately 5% of the avoidable blindness.

Clinical and genetic heterogeneity in autosomal dominant cataract

AIMS

To determine the different morphologies of autosomal dominant cataract (ADC), assess the intra- and interfamilial variation in cataract morphology, and undertake a genetic linkage study to identify loci for genes causing ADC and detect the underlying mutation.

METHODS

Patients were recruited from the ocular genetic database at Moorfields Eye Hospital. All individuals underwent an eye examination with particular attention to the lens including anterior segment photography where possible. Blood samples were taken for DNA extraction and genetic linkage analysis was carried out using polymorphic microsatellite markers.

RESULTS

292 individuals from 16 large pedigrees with ADC were examined, of whom 161 were found to be affected. The cataract phenotypes could all be described as one of the eight following morphologies-anterior polar, posterior polar, nuclear, lamellar, coralliform, blue dot (cerulean), cortical, and pulverulent. The phenotypes varied in severity but the morphology was consistent within each pedigree, except in those affected by the pulverulent cataract, which showed considerable intrafamilial variation. Positive linkage was obtained in five families; in two families linkage was demonstrated to new loci and in three families linkage was demonstrated to previously described loci. In one of the families the underlying mutation was isolated. Exclusion data were obtained on five families.

CONCLUSIONS

Although there is considerable clinical heterogeneity in ADC, the phenotype is usually consistent within families. There is extensive genetic heterogeneity and specific cataract phenotypes appear to be associated with mutations at more than one chromosome locus. In cases where the genetic mutation has been identified the molecular biology and clinical phenotype are closely associated.

Management of monocular congenital cataracts

Monocular congenital cataracts have been treated for the past two decades with early surgery, contact lens correction and patching of the unaffected eye. While an occasional patient has had a good visual outcome with this treatment regiment, the majority end up being legally blind in the aphakic eye. Intraocular lenses (IOLs) are increasingly being used as an alternative means of optically correcting aphakia during infancy. A growing body of literature suggests that an IOL correction is associated with an improved visual outcome and a relatively low incidence of post-operative complications. A monkey model has also been used to study the safety and feasibility of correcting aphakia in neonates with IOLs. These studies have revealed that the visual outcome is as good if not better with an IOL correction. A multicentre clinical trial, the Infant Aphakia Treatment Study (IATS), is being organised in the United States to critically compare an IOL and contact lens correction for infantile aphakia.

Primary posterior capsulorhexis without anterior vitrectomy in pediatric cataract surgery: longer-term outcome

PURPOSE

To assess the effectiveness of primary posterior capsulorhexis without anterior vitrectomy in preventing posterior capsule opacification (PCO) in pediatric cataract surgery.

SETTING

Children's Hospital, Dublin, Republic of Ireland.

METHODS

The study comprised 32 eyes of 22 pediatric patients who had cataract extraction between 1994 and 1998. Extracapsular cataract extraction was performed using radiofrequency diathermy capsulorhexis to the anterior and posterior capsules without an anterior vitrectomy. Posterior chamber intraocular lens implantation was performed in 20 eyes. There were 23 congenital, 6 developmental, and 3 traumatic cataracts.

RESULTS

Patient age ranged from 1 month to 12 years. Mean follow-up was 19 months (range 6 to 50 months). Twenty-seven of 32 eyes (84.4%) had a clear visual axis at last follow-up. Five eyes required a neodymium: YAG capsulotomy, which was performed a mean of 5 months postoperatively (range 1 to 9 months). The incidence of PCO requiring capsulotomy was 15.6%.

CONCLUSION

Primary posterior capsulorhexis without anterior vitrectomy was safe and effective, with a low reopacification rate. Long-term follow-up of this patient cohort is necessary.

Connexin46 mutations in autosomal dominant congenital cataract

Loci for autosomal dominant "zonular pulverulent" cataract have been mapped to chromosomes 1q (CZP1) and 13q (CZP3). Here we report genetic refinement of the CZP3 locus and identify underlying mutations in the gene for gap-junction protein alpha-3 (GJA3), or connexin46 (Cx46). Linkage analysis gave a significantly positive two-point LOD score (Z) at marker D13S175 (maximum Z [Zmax]=>7.0; maximum recombination frequency [thetamax] =0). Haplotyping indicated that CZP3 probably lies in the genetic interval D13S1236-D13S175-D13S1316-cen-13pter, close to GJA3. Sequencing of a genomic clone isolated from the CZP3 candidate region identified an open reading frame coding for a protein of 435 amino acids (47,435 D) that shared approximately 88% homology with rat Cx46. Mutation analysis of GJA3 in two families with CZP3 detected distinct sequence changes that were not present in a panel of 105 normal, unrelated individuals. In family B, an A-->G transition resulted in an asparagine-to-serine substitution at codon 63 (N63S) and introduced a novel MwoI restriction site. In family E, insertion of a C at nucleotide 1137 (1137insC) introduced a novel BstXI site, causing a frameshift at codon 380. Restriction analysis confirmed that the novel MwoI and BstXI sites cosegregated with the disease in families B and E, respectively. This study identifies GJA3 as the sixth member of the connexin gene family to be implicated in human disease, and it highlights the physiological importance of gap-junction communication in the development of a transparent eye lens.

Genetic diseases and gene knockouts reveal diverse connexin functions

Intercellular channels present in gap junctions allow cells to share small molecules and thus coordinate a wide range of behaviors. Remarkably, although junctions provide similar functions in all multicellular organisms, vertebrates and invertebrates use unrelated gene families to encode these channels. The recent identification of the invertebrate innexin family opens up powerful genetic systems to studies of intercellular communication. At the same time, new information on the physiological roles of vertebrate connexins has emerged from genetic studies. Mutations in connexin genes underlie a variety of human diseases, including deafness, demyelinating neuropathies, and lens cataracts. In addition, gene targeting of connexins in mice has provided new insights into connexin function and the significance of connexin diversity.

National cross sectional study of detection of congenital and infantile cataract in the United Kingdom: role of childhood screening and surveillance. The British Congenital Cataract Interest Group

OBJECTIVES

To determine the mode of detection and timing of ophthalmic assessment of a nationally representative group of children with congenital and infantile cataract.

DESIGN

Cross sectional study.

SETTING

United Kingdom.

SUBJECTS

All children born in the United Kingdom and aged 15 years or under in whom congenital or infantile cataract was newly diagnosed between October 1995 and September 1996.

MAIN OUTCOME MEASURES

Proportion of cases detected through routine ocular examination and proportion assessed by an ophthalmologist by 3 months and 1 year of age.

RESULTS

Data were complete for 235 (95%) of 248 children identified. Of these, 83 (35%) were detected at the routine newborn examination and 30 (12%) at the 6-8 week examination; 82 children presented symptomatically. 137 (57%) children had been assessed by an ophthalmologist by the age of 3 months but 78 (33%) were not examined until after 1 year of age. In 91 cases the child's carers suspected an eye defect before cataract was diagnosed.

CONCLUSIONS

A substantial proportion of children with congenital and infantile cataract are not diagnosed by 3 months of age, although routine ocular examination of all newborn and young infants is recommended nationally. Strategies to achieve earlier detection through screening and surveillance are required.

Visual outcome after paediatric cataract surgery: is age a major factor?

AIMS

To determine functional results after unilateral and bilateral cataract surgery in children with different aphakic optical correction.

METHODS

In this retrospective study, we evaluated visual acuity and binocular vision in 107 children who underwent cataract surgery during the 10 year period from 1985 to 1995. Aphakia was corrected by an intracapsular intraocular lens (IOL), spectacles or contact lenses.

RESULTS

Mean visual acuity was > 20/40 (< 0.3 log MAR) with normal binocular vision in 58 children over 7 months of age operated on for bilateral cataracts. Pseudophakic eyes regained visual acuity > 20/63 (< 0.5 log MAR) more often (90%) than aphakic eyes (46%) (p < 0.001). Binocular vision was also achieved more often after IOL implantation (p < 0.001). Visual outcome of early bilateral cataracts was less satisfactory in children with abnormal foveolar function. For 49 children who had surgery for unilateral cataracts, prognosis was poor when surgery was performed before the age of 7 months. For cataract surgery in older children (> or = 7 months) mean visual acuities were better with IOL implantation (p < 0.05).

CONCLUSION

Cataract surgery with unilateral and bilateral IOL implantation can provide a beneficial effect on final visual outcome in children who are operated on before abnormal foveolar function develops.

Intraocular lens calculator for childhood cataract

PURPOSE

To evaluate a computer program to predict the pseudophakic refraction of a child at any age.

SETTING

A pediatric ophthalmology practice.

METHODS

A computer program was written for Windows 95 that calculates the initial postoperative pseudophakic refraction of a child using Holladay's formula, given the axial length and keratometry readings. The logarithmic model was used to predict the ultimate refraction at age 20 years and chart the predicted curve of refractive error with standard deviations.

RESULTS

The program provided a graph of a child's predicted pseudophakic refraction versus age that would allow the surgeon to dynamically view the effects of changing the intraocular lens (IOL) power.

CONCLUSIONS

If pseudophakia and aphakia have the same effect on the growth of the eye, this program should accurately predict the myopic shift of a pseudophakic child. This could help guide the surgeon's choice of IOL power.

Pediatric intraocular lens implantation. Surgical results and complications in more than 300 patients

OBJECTIVE

The study aimed to review pediatric intraocular lens (IOL) implantations performed in the authors' institution for the past 7 years.

STUDY DESIGN

The study design was a retrospective chart review.

PARTICIPANTS

All children who underwent IOL placement between January 1, 1989, and January 31, 1996, at ages 2 to 16 years were studied. Follow-up was a minimum of 6 months up to 4 years with an average of 13 months.

INTERVENTION

Placement of a primary or secondary posterior chamber IOL was performed.

MAIN OUTCOME MEASURES

Visual acuity and possible complications were tabulated.

RESULTS

Fifty-seven percent of the cataracts were caused by trauma, and 37% were infantile cataracts. Visual acuities of 20/40 or better were attained in 44% of eyes and visual acuities of 20/50 to 20/80 were attained in 27% of eyes. Visual acuities were better in children older than 4 years of age (P = 0.001). Compliance with amblyopia therapy improved vision (P = 0.004). Fibrinous membranes occurred in 41 eyes (13%), and posterior capsule opacification occurred in 120 eyes (39%). There were no significant differences in visual outcome and complications between primary and secondary implants (17%) or between capsular bag and sulcus fixation (27%). The first stable postoperative refraction was predicted accurately in most patients, based on the Sanders-Retzlaff-Kraff II (SRK II) formula and intraoperative corneal curvature and axial length determinations. The mean refraction differed from the goal by only +0.28 diopter and 84% were within +/- 2 diopters. A few patients showed large overcorrections or undercorrections. On average, no myopic shift occurred.

CONCLUSIONS

Short-term results of IOLs implanted in children older than 2 years of age were favorable. Visual acuities obtained were better than 20/80 in 71% despite a high prevalence (28%) of penetrating trauma. Major complications were rare.

Theoretic refractive changes after lens implantation in childhood

OBJECTIVE

Children with aphakia tend to have decreasing hyperopia as they grow older. No large study of the long-term refractive changes in children with pseudophakia has been published, although myopic shifts of greater than 10 diopters (D) have been reported. The authors used the refractions of children with aphakia and long follow-up to calculate the theoretic long-term refractive effects of pseudophakia.

DESIGN

The study design was a chart review of eyes that underwent cataract surgery before age 10 with documented refractions for more than 7 years.

PARTICIPANTS

Ninety-three eyes were studied.

INTERVENTION

The initial aphakic refractions of the study eyes were used to calculate the intraocular lens (IOL) powers that would have been required to give emmetropia at cataract removal. The aphakic refractions at last follow-up were used to calculate the final pseudophakic refractions, and these were compared with the predictions of a logarithmic model of myopic shift.

RESULTS

The mean follow-up time was 11 years. The median calculated pseudophakic refraction at last follow-up was -6.6 D with a range of -36.3 to +2.9 D. Children who underwent surgery in the first 2 years of life had a substantially greater myopic shift than older children (P < 0.001) and a larger variance in this myopic shift (P < 0.001). The logarithmic model accurately predicted the final refraction within 3 D in 24% of eyes undergoing surgery before 2 years of age and in 77% of eyes undergoing surgery after this age.

CONCLUSIONS

Pseudophakia in children is predicted to result in a large quantity of myopic shift, particularly in very young children. An IOL power chosen to leave a child initially hyperopic should lessen both the quantity of myopic shift and the extreme myopia that can result with growth. The surgeon who implants IOLs in young children must be prepared for a wide variation in long-term myopic shift.

Traumatic cataract in children: correction of aphakia by contact lens or intraocular lens

PURPOSE

To compare the postoperative complications, visual outcome, and incidence of strabismus in children suffering from traumatic cataract corrected with contact lens or intraocular lens and to follow up the refractive changes in these eyes for an extended period of time.

METHODS

Forty children, 2 to 13 years old at time of surgery for unilateral traumatic cataract, were followed up for 1.5 to 11 years. Seventeen children were corrected with contact lenses and 23 with intraocular lenses. Thirty-two underwent a primary posterior capsulectomy and anterior vitrectomy.

RESULTS

The mean follow-up after surgery was 7.4 years for the children with contact lenses and 6.2 years for those with intraocular lenses. The incidence of secondary surgical interventions was higher among the children corrected with contact lenses. The eight children (five with contact lenses, three with intraocular lenses) who did not undergo primary posterior capsulectomy had Nd:YAG capsulectomy within 1 year after surgery. Fifteen of the 23 children with intraocular lenses (65.2%) achieved a best-corrected visual acuity of 20/40, and 17 children (73.9%) had a final visual acuity of 20/50, but only five of 17 children with contact lenses (35.3%) achieved this level of visual acuity.

CONCLUSIONS

Correction of unilateral aphakia by intraocular lens in children after traumatic cataracts results in better final visual acuities and binocularity with a smaller incidence of strabismus than when correction is carried out by contact lens. Intraocular lens implantation should be considered the primary aphakic correction in children with traumatic cataract.

Corneal edema after pediatric cataract surgery

INTRODUCTION

We have encountered idiopathic corneal edema in four patients (five eyes) after pediatric lensectomy. This problem has not been previously described in the pediatric ophthalmology literature.

METHODS

Clinical and operative records were reviewed. The children, who ranged in age from 15 months to 6 years, underwent apparently uncomplicated limbal lensectomy without lens implantation. After surgery, all received subconjunctival hydrocortisone (12.5 mg) and 2 to 4 drops daily of topical prednisolone acetate. The corneal edema developed between 2 and 14 days after surgery.

RESULTS

The condition cleared in all patients during a 5- to 14-day course of intensive topical steroids. No sequelae have been apparent. Final visual acuities are 20/30 or better in the three children (four eyes) old enough for recognition acuity testing. The fifth eye has excellent central fixation.

CONCLUSIONS

We suspect that the corneal decompensation was a manifestation of sterile inflammation. Two of the children had a history of iritis. Difficulty measuring cellular response at the slit-lamp examination and instilling eyedrops at home may have contributed to the complication. Postoperative corneal decompensation can be responsive to topical steroids, which we now prescribe more intensively even in apparently quiet eyes.

A new locus for dominant "zonular pulverulent" cataract, on chromosome 13

Inherited cataract is a clinically and genetically heterogeneous disease that most often presents as a congenital autosomal dominant trait. Here we report the linkage of a new locus for dominant "zonular pulverulent" cataract (CZP) to chromosome 13. To map the CZP locus we performed molecular-genetic linkage analysis using microsatellite markers in a five-generation English pedigree. After exclusion of eight known loci and several candidate genes for autosomal dominant cataract, we obtained significantly positive LOD scores (Z) for markers D13S175 (maximum Z [Zmax] = 4.06; maximum recombination frequency [theta max] = 0) and D13S1236 (Zmax = 5.75, theta max = 0). Multipoint analysis gave Zmax = 6.62 (theta max = 0) at marker D13S175. Haplotype data indicated that CZP probably lies in the centromeric region of chromosome 13, provocatively close to the gene for lens connexin46.

Secondary intraocular lens implantation after cataract surgery in children

PURPOSE

To report results of secondary intraocular lens implantation after cataract surgery in children.

METHODS

We reviewed clinical records for a 5-year period of patients who had cataract surgery in childhood and received a secondary intraocular lens implant. We studied indications for secondary intraocular lens placement; surgical procedures for intraocular lens implantation; preoperative and postoperative visual acuity, refractive error, and binocular status; and complications of the procedure.

RESULTS

A secondary intraocular lens was placed in 28 eyes of 25 patients who had cataract surgery in childhood. In 20 eyes, the lenses were placed in the ciliary sulcus. The other eight eyes had insufficient capsular support for an intraocular lens; in two, the intraocular lens was placed in the anterior chamber and, in six, in the posterior chamber with suture fixation to the sclera. Twenty of 28 eyes (71%) had measurable improvement in visual acuity; only one eye had a decrease in visual acuity of 2 lines. Fifteen patients (54%) had a final refraction within 1.50 diopters of the fellow eye; 21 (75%) were within 3.00 diopters. During follow-up, two eyes developed glaucoma. One had transient pressure elevation; one required two filtration procedures. Three patients required Nd:YAG capsulotomy. Six patients demonstrated Worth fusion at distance and near; three demonstrated 200 seconds of arc or better stereo visual acuity.

CONCLUSION

Secondary placement of an intraocular lens in the posterior chamber appears to be a safe, effective alternative for correction of aphakia in the contact lens- or spectacles-intolerant child or young adult.

Radiofrequency diathermy capsulorhexis of the anterior and posterior capsules in pediatric cataract surgery: preliminary results

PURPOSE

To assess the effectiveness of radiofrequency diathermy capsulorhexis in preventing opacification of the posterior capsule in pediatric cataract extraction.

SETTING

The Children's Hospital, Dublin, Ireland.

METHODS

Radiofrequency diathermy capsulorhexis to the anterior capsule followed by injection of sodium hyaluronate behind the posterior capsule and primary posterior capsule diathermy capsulorhexis were performed in 14 eyes of 7 children requiring cataract surgery.

RESULTS

Six patients had bilateral congenital and 1 patient bilateral developmental cataracts. Ten eyes (5 patients) received heparin-surface-modified intraocular lenses, and 4 eyes (2 patients) were left aphakic. There were no intraoperative complications, and only mild anterior segment inflammation was noted postoperatively.

CONCLUSION

With follow-up from 7 to 16 months (mean 12.1 months), our results showed no epithelial regrowth or opacification of the posterior capsule following diathermy capsulorhexis.

Epidemiology of cataract in childhood: a global perspective

Cataract is the most important cause of treatable childhood blindness. There are an estimated 200,000 children blind from cataract worldwide; 20,000 to 40,000 children with developmental bilateral cataract are born each year. Rubella is still an important cause of preventable disease in many countries. In the developing world, there is a need to improve early case detection and referral services and to establish centers with expertise in the assessment, surgical treatment, and long-term management of the child with cataract.

Choice of lens and dioptric power in pediatric pseudophakia

PURPOSE

To evaluate lens choice and dioptric power in pediatric eyes having posterior chamber intraocular lens (IOL) implantation.

SETTING

Oxford Eye Center and the St. John Eye Hospital, Johannesburg, South Africa.

METHODS

This retrospective study evaluated the refractive development in 156 pseudophakic eyes of 99 children aged 1 month to 8 years who had surgery between June 1983 and April 1994. The children were divided into three groups based on age at time of IOL implantation: Group A (68 eyes), 1 to 18 months; Group B (32 eyes), 19 to 36 months; Group C (48 eyes), 3 to 8 years. Poly(methyl methacrylate) posterior chamber IOLs with an overall diameter between 10.5 and 12.0 mm were used. The dioptric power was 3.00 to 6.00 diopters (D) less than that needed to achieve emmetropia.

RESULTS

In Group A, the mean growth in axial length was 3.59 mm +/- 1.80 (SD) and the mean change in refraction was 6.39 +/- 3.68 D. In Group B, the respective means were 0.75 +/- 0.85 mm and 2.73 +/- 1.40 D and in Group C, 0.76 +/- 0.69 mm and 2.60 +/- 1.84 D.

CONCLUSIONS

The younger the child at time of implantation, the greater the myopic shift. To reduce the necessity of IOL exchange, these eyes should be undercorrected, with the residual refractive error corrected by spectacles that are adjusted throughout life according to refractive development. This leads to initial hypermetropia that gradually moves to emmetropia or moderate myopia in adulthood.