Mutational analysis and genotype-phenotype correlations in southern Indian patients with sporadic and familial aniridia.

PURPOSE: Aniridia is a rare panocular disorder characterized by iris hypoplasia and other associated eye anomalies. Heterozygous null mutations in paired box gene 6 (PAX6) are the major cause of the classic aniridia phenotype. This study aims to detect the mutational spectrum of PAX6 and associated phenotypes in southern Indian patients with sporadic and familial aniridia. METHODS: Genomic DNA was isolated from peripheral blood from all participants. The coding regions and flanking intronic sequences of PAX6 were screened with Sanger sequencing in 30 probands with aniridia. The identified variations were further evaluated in available family members and 150 healthy controls. The pathogenic potential of the mutations were assessed using bioinformatics tools. RESULTS: Thirteen different mutations were detected in eight sporadic and five familial cases. Eleven novel mutations, including five insertions (c.7_10dupAACA, c.567dupC, c.704dupC, c.868dupA and c.753_754insTA), two deletions (c.242delC and c.249delT), and four splicing variants (c.10+1G>A, c.141G>A, c.141+4A>G and c.764A>G) were identified in this study. Clinical findings of the patients revealed phenotypic heterogeneity with the same or different mutations. CONCLUSIONS: This study reported 11 novel mutations and thus expanded the spectrum of PAX6 mutations. Interestingly, all mutations reported in this study were truncations, which confirms the hypothesis that haploinsufficiency of PAX6 causes the aniridia phenotype. Our observations revealed inter- and intrafamilial phenotypic variability with PAX6 mutations. The common ocular findings associated with PAX6 mutations were iris hypoplasia, nystagmus, and foveal hypoplasia reported in almost all cases, with cataract, glaucoma, and keratopathy reported in approximately 50% of the patients.

Ocular signs, visual and general developmental outcome in Indian children with radiologically proven periventricular leukomalacia.

PURPOSE: Owing to the paucity of literature on Indian children with periventricular leukomalacia (PVL), this retrospective study aimed to describe the visual and associated developmental abnormalities in a series of affected children attending a tertiary level eye care facility. METHODS: Children with radiologically confirmed PVL who attended the Pediatric Department of a tertiary eye hospital were included and underwent a detailed ocular and general developmental assessment. RESULTS: Of the 75 children, the mean age was 2.3 years, the mean follow-up was 3.1 years, 68% were males and 43% were born preterm. Grade I PVL was identified in 13 children (17%), Grade 2 PVL in 39 (52%), and Grade 3 PVL in 23 (31%). Premies with ≤2 kg (72.5%) and term babies with >2 kg (75%) had a greater association of PVL occurrence with a preponderance to severe PVL; 46% of the children were visually impaired which was significantly higher in the children with Grade 3 PVL (74%) than those with Grade 2 PVL (15%). Strabismus was common (80%) with a change in deviation over time. Seventy-one percent of the children had a refractive error, frequently myopic astigmatism. All the children except two had a delay in one or more general developmental milestones. CONCLUSION: PVL occurrence is observed both in the babies born at term and premies, resulting in significant ocular and systemic morbidities. We recommend a system in place for early identification and referral to initiate an early intervention program which goes a long way toward improving the quality of life in these children.

Incomplete penetrance and phenotypic variability characterize Gdf6-attributable oculo-skeletal phenotypes.

Proteins of the bone morphogenetic protein (BMP) family are known to have a role in ocular and skeletal development; however, because of their widespread expression and functional redundancy, less progress has been made identifying the roles of individual BMPs in human disease. We identified seven heterozygous mutations in growth differentiation factor 6 (GDF6), a member of the BMP family, in patients with both ocular and vertebral anomalies, characterized their effects with a SOX9-reporter assay and western analysis, and demonstrated comparable phenotypes in model organisms with reduced Gdf6 function. We observed a spectrum of ocular and skeletal anomalies in morphant zebrafish, the latter encompassing defective tail formation and altered expression of somite markers noggin1 and noggin2. Gdf6(+/-) mice exhibited variable ocular phenotypes compatible with phenotypes observed in patients and zebrafish. Key differences evident between patients and animal models included pleiotropic effects, variable expressivity and incomplete penetrance. These data establish the important role of this determinant in ocular and vertebral development, demonstrate the complex genetic inheritance of these phenotypes, and further understanding of BMP function and its contributions to human disease.

Down syndrome with bilateral posterior lenticonus.

We present a case of bilateral posterior lenticonus in a young boy with Down syndrome. Association of posterior lenticonus in Down syndrome is rarely reported in the literature. We have discussed the clinical features and management of this patient at our hospital.

Crystallin gene mutations in Indian families with inherited pediatric cataract.

PURPOSE: Pediatric cataract is the most common form of treatable childhood blindness and is both clinically and genetically heterogeneous. Autosomal dominant and recessive forms of cataract have been reported to be caused by mutations in 22 different genes so far. Of the cataract mutations reported to date, about half the mutations occur in crystallins, a quarter of the mutations in connexins, and the remainder is evenly divided between intrinsic membrane proteins, intermediate filament proteins, and transcription factors. This study is aimed at identification of the spectrum and frequency of crystallin gene mutations in cataractous patients in an Indian population. METHODS: Genetic analysis was extended to screen the entire coding region of the CRYAA, CRYAB, CRYBA1, CRYBA4, CRYBB1, CRYBB2, CRYBB3, CRYGC, CRYGD, and CRYGS genes using single stranded conformational polymorphism (SSCP) analysis as a screening technique followed by direct sequencing of all subjects that displayed an electrophoretic shift. RESULTS: This report describes the first simultaneous mutation analysis of 10 crystallin genes in the same population, represented by 60 south Indian families. The analysis allowed the identification of causative mutations in 10 of the families (three novel and six reported). This includes six missense mutations (CRYAA-R12C, R21W, R54C, CRYAB- A171T, CRYGC-R168W, CRYGS- S39C), two nonsense mutations (CRYBB2- Q155X, CRYGD- R140X), and one splice mutation, which was identified in two families (CRYBA1-IVS3+1G>A). CONCLUSIONS: Crystallin mutations are responsible for 16.6% of the inherited pediatric cataract in this population. As causative mutations have not been found in many of the families analyzed, this study suggests the presence of further novel genes or sequence elements involved in the pathogenesis of cataract in these families.

Pigmented free-floating retrolental space cyst.

We report an unusual case of a free-floating pigmented retrolental cyst, which was diagnosed after examination by slitlamp, B-scan ultrasonography, and ultrasound biomicroscopy. Pigmented cysts, which may arise from the ciliary body epithelium, are embryologically and morphologically different from clear cysts.

Electroretinographic assessment and diagnostic reappraisal of children with visual dysfunction: a prospective study.

PURPOSE: To assess the presence or absence of a retinal cause of visual impairment using electroretinography (ERG) in children with no obvious discernable cause on ocular examination. DESIGN: Prospective observational case series. MATERIALS AND METHODS: A prospective study was carried out involving 120 children with the mean age 4.4+/-3.2 years with visual dysfunction. All children underwent ERG under general anesthesia using a special handheld mini-Ganzfeld (Kurbisfeld) dome. RESULTS: Fifty-two (43.3%) children were male and 68 (56.7%) were female. The clinical diagnosis was as follows: Leber's congenital amaurosis (LCA) (n=47), achromatopsia (n=25), congenital stationary night blindness (CSNB) (n=9) and others (unclassifiable, n=39). The visual acuity ranged from perception of light (PL) to PL with projection in children with LCA. In the rest (n=73), some sort of visually guided behavior was discernable. Following ERG, a diagnostic reappraisal resulted as follows: LCA (n=49), achromatopsia (n=28), CSNB (n=4), cone-rod dystrophy (n=22), rod-cone degeneration (n=7), normal (n=8) and others (unclassifiable, n=2). Except for the two unclassifiable cases, ERG was successful in the diagnosis or exclusion of retinal dysfunction in the rest. By Pearson Chi-square test, there was a statistically significant association between the clinical and ERG diagnosis (P < 0.001). CONCLUSION: LCA was the commonest cause of visual dysfunction in our series. A statistically significant correlation between clinical and electrophysiological diagnosis was seen. ERG helped in firmly establishing the presence or absence of global retinal dysfunction in the majority (118/120) of pediatric patients with visual dysfunction.

Retinitis pigmentosa associated with blepharophimosis, blue dot cataract and primary inferior oblique overaction: a new syndrome complex?

A 15-year-old girl with retinitis pigmentosa, blepharophimosis, blue dot cataract and primary overaction of inferior oblique muscle in both the eyes is being reported. Computerized search using Medline did not reveal any such previously reported association.

Novel mutations in GJA8 associated with autosomal dominant congenital cataract and microcornea.

PURPOSE: The purpose of this study was to estimate the importance of mutations in the connexin50 gene (GJA8) as a cause of congenital or developmental cataracts in the Indian population and to identify novel mutations in GJA8 that cause cataract in this population. METHODS: The coding region of GJA8 was analyzed for mutation by single strand conformational polymorphism in 60 probands affected with congenital or developmental cataract of which 11 probands' corneal diameter measured less than 11.00 mm. Direct sequencing was performed for samples that displayed an abnormal electrophoresis pattern. The segregation of the change with the diseased phenotype was analyzed in the entire pedigree by restriction fragment length polymorphism (RFLP) analysis. RESULTS: Molecular analysis of GJA8 revealed two novel missense mutations V44E and R198Q, in the population screened. The mutations cosegregated with the diseased phenotype in an autosomal dominant manner and were absent in 400 normal control chromosomes analyzed. GJA8 mutations were seen in two of the 60 unrelated probands with cataracts. Affected individuals in both of whose families also had microcornea and variable myopia. CONCLUSIONS: This is the first report of mutations in GJA8 to be associated with autosomal dominant cataract and microcornea. Mutations in GJA8 cause 3.3% of congenital cataracts in the population of India.

PAX6 missense mutations associated in patients with optic nerve malformation.

PURPOSE: PAX6 missense mutations are likely to cause a spectrum of ocular, neurological, and systemic developmental defects and have been reported in various ethnic groups. The purpose of this study was to investigate the clinical features of optic nerve malformation caused by PAX6 mutations in Indian patients. METHODS: Total genomic DNA was isolated from peripheral blood of 27 sporadic probands affected with congenital optic nerve malformation, unaffected family members, and 50 unrelated age-matched controls. Informed consent was obtained from all study subjects. Polymerase chain reaction was carried out to explore PAX6 defective alleles using single-strand conformation analysis (PCR-SSCA) followed by automated bidirectional sequencing. RESULTS: We identified two novel PAX6 missense mutations in two unrelated sporadic probands. The mutation analysis revealed variation at position c.469G>C, codon 36 in proband ONH 4-1 with optic nerve hypoplasia. The other de novo mutation was observed at c.514G>C, codon 51 in proband ODC 5-1 with optic disc coloboma. Both G>C base substitutions cause a relatively conservative amino acid change, altering glycine to alanine residues within the paired DNA-binding domain. CONCLUSIONS: In this study, we have been able to identify two sequence variations in the PAX6 gene. These missense mutations may uniquely alter the structure and expression of PAX6 protein, resulting in distinct clinical phenotypes. Mutation analysis of 27 probands for PAX6 has resulted in only two significant variants. This finding demonstrated that the frequency of PAX6 mutations associated with optic nerve malformation is low, requiring the elucidation of other candidate genes in other patients.

Immune status of health care personnel & post vaccination analysis of immunity against rubella in an eye hospital.

BACKGROUND & OBJECTIVES: Congenital rubella syndrome (CRS) accounts for a significant amount of mortality and morbidity in India. Rubella vaccination is not included in our national immunization programme. Occupational exposure of the health care personnel to rubella infection is well known. This study aims to assess the serological status of health care workers against rubella virus in Aravind Eye Care System, Madurai and to follow the immune response in the seronegative individuals after vaccination. METHODS: A total of 500 female and 81 male workers were enrolled in the study. Blood sample was collected for the analysis of rubella specific IgM and IgG antibodies. The seronegative individuals were vaccinated with monovalent rubella vaccine, RA 27/3. The post-vaccination samples were analysed for the antibody levels and their avidity using enzyme immunoassay. RESULTS: Of the 581 volunteers, 493 were seropositive with good protective immunity and 22 had both IgM and IgG antibodies. Sixty six volunteers (59 females and 7 males) were found to be seronegative to rubella. The seroconversion was observed in all the sixty vaccinated individuals, as seen by the appearance of anti-rubella IgG antibodies by fourth week, reaching the peak protective levels (>20 IU/ml) by third month. There was also a progressive increase in the avidity after vaccination. INTERPRETATION & CONCLUSION: Nearly 11.4 per cent of the health care workers were found to be seronegative for rubella virus and after vaccination, these volunteers developed a good protective immunity, thereby reducing the risk of contracting the hospital based rubella infection. Therefore, rubella vaccination may be instituted in hospitals for the benefit of health care workers.

Identification of novel mutant PAX6 alleles in Indian cases of familial aniridia.

BACKGROUND: Haploinsufficiency at the PAX6 locus causes aniridia, a panocular eye condition characterized by iris hypoplasia and a variety of other anterior and posterior eye defects leading to poor vision. This study was performed to identify novel PAX6 mutations that lead to familial aniridia in Indian patients. METHODS: Genomic DNA was isolated from affected individuals (clinically diagnosed aniridia) from nine unrelated aniridic pedigrees, unaffected family members, and unrelated normal controls. The coding regions of PAX6 were amplified and subjected to single strand conformation polymorphism (SSCP) gel analysis, and direct cloning and sequencing. RESULTS: SSCP band shifts, indicative of DNA base pair mutations, were observed in five of these unrelated families. Four mutations were shown to be previously unreported insertion or deletions in PAX6, leading to frameshifts. These new mutations were c.1174delTG (in exon 10), c.710delC (exon 6), c.406delTT (exon 5) and c.393insTCAGC (exon 5). The other nonsense mutation, a transition (c.1080C>T) in exon 9, has been reported previously as a mutation hotspot for PAX6 in other ethnic pedigrees. All mutant alleles transmitted through aniridic individuals in each family. CONCLUSION: These new deletions and an insertion create frameshifts, which are predicted to introduce premature termination codons into the PAX6 reading frame. The genetic alterations carried by affected individuals are predicted to lead to loss-of-function mutations that would segregate in an autosomal dominant manner to subsequent generations. This is the first report of the 'hotspot' c.1080C>T transition from Indian families.

Ocular Morbidity Associated With Retinopathy of Prematurity in Treated and Untreated Eyes: A Review of the Literature and Data From a Tertiary Eye-care Center in Southern India.

Retinopathy of prematurity (ROP) is an emerging cause of childhood blindness in low- and middle-income countries. We review the magnitude, causes, prevention and treatment of visual impairment caused by ROP over a time span. A review of literature on short and long term structural and functional outcomes of ROP was conducted through PubMed search primarily focusing on studies published during the last decade. Additionally, we have shared data from our institute located in Southern India. Visual Impairment in ROP-treated children ranged from 4.1% to 30% in various settings, attributable mainly to refractive errors, amblyopia, strabismus and perinatal neurological events followed by structural changes like macular scarring and retinal detachment. We conclude that towards an early detection and a proper management of all the above mentioned conditions, these children need to be followed-up for a long time by a committed pediatric ophthalmologist at a specifically scheduled interval. The overall success depends upon the strength of the networking system between parents/neonatologists/pediatricians/pediatric ophthalmologist and a retina specialist.

Double Augmented Vertical Rectus Transposition for Large-Angle Esotropia Due to Sixth Nerve Palsy.

PURPOSE: To study the binocular alignment and ocular motility in patients with large-angle esotropia due to sixth nerve palsy treated with double augmented vertical recti transposition. METHODS: This was a prospective interventional study. Fifteen patients with non-resolving sixth nerve palsy who underwent surgical correction were included in the study. Fourteen patients also underwent an additional medial rectus recession. Two patients with an associated small vertical deviation had a selective augmentation of one vertical rectus muscle. Binocular alignment, ocular motility, duction limitation, improvement in head posture, induced vertical deviations, and field of diplopia-free binocular single vision (when possible) were analyzed. Successful outcome was defined as a residual horizontal deviation of 10 prism diopters (PD) or less with no vertical deviation at final follow-up (6 months). RESULTS: The double augmented Hummelsheim procedure improved esotropia from 58.3 ± 10.8 PD preoperatively to 7.2 ± 5.1 PD postoperatively (P = .001). Three (20%) patients had residual deviation of greater than 10 PD, of which 1 patient had diplopia and was treated with prisms. Postoperative binocular field of vision was performed in 6 patients, the mean of which was 20° for abduction and 45° for adduction. Three of 6 patients had elimination of face turn and the rest had residual head posture of less than 5°. Two patients had an induced vertical deviation of less than 4 PD. In patients who had selective augmentation, the vertical deviation was completely corrected. CONCLUSIONS: The patients operated on with double augmentation of the Hummelsheim procedure combined with medial rectus recession had reduced mean primary esotropia and improved diplopia-free field of vision postoperatively. [J Pediatr Ophthalmol Strabismus. 2016;53(6):369-374.].

Novel mutations in GJA3 associated with autosomal dominant congenital cataract in the Indian population.

PURPOSE: Connexin 46 (Cx46) is crucial in the maintenance of lens homeostasis and it is known to be expressed mainly in the terminally differentiated lens fiber cells. The present study aimed to identify the spectrum of mutations in Connexin 46 in the Indian population. METHODS: PCR based Single Stranded Conformational Polymorphism (SSCP) analysis was used to screen sixty probands with nonsyndromic congenital cataract for mutations in the Cx46 gene (GJA3), followed by direct sequencing of samples that showed an electrophoretic shift. Mutation predicted to affect the coding sequence were subsequently analyzed in the entire pedigree. RESULTS: Two novel missense mutations were identified in Cx46. The mutation in Family 1 was characterized as R76G with a total cataract phenotype. A V28M missense mutation was identified in family 2, the cataract phenotype varied in its severity and the age of onset. The mutation was also identified in 2 unaffected individuals of the family and the intrafamilial variation of the disease suggests the possibility of a modifier gene(s) or the effects of environmental factors being involved. The mutation was identified in all the affected members in the family and found to be absent in 400 ethnically matched control chromosomes analyzed. CONCLUSIONS: We conclude that connexin 46 mutations might account for as much as 3.3% of the hereditary congenital cataract in the Indian population.

The impact of visual impairment on functional vision of children in rural South India: the Kariapatti Pediatric Eye Evaluation Project.

PURPOSE: To determine the impact of visual impairment on functional vision of children in a rural population of south India. METHODS: A visual function questionnaire (LVP-VFQ) was administered to 1194 children aged 7 to 15 years identified through a systematic random sampling technique from 144 hamlets of Kariapatti in rural south India as part of a larger population-based project. Visual acuity estimations and clinical examinations for morbidity were performed in these 1194 children. A Rasch analysis was performed to validate the use of the instrument in this population. Bootstrap estimates (95% confidence intervals) of the regression coefficients were used to compare visual function scores between children with normal sight and children with uncorrected monocular and binocular visual impairment. RESULTS: The mean age of children was 10.3 +/- 2.1 years. The reliability estimates were 0.82 for person ability and 0.88 for item difficulty parameters, according to the Rasch analysis. A separation index of 2.15 was obtained for person measures and 2.74 for item measures, and the mean square infit and outfit statistics were 1.03 (Z(STD) 0.1) and 0.99 (Z(STD) -0.1), respectively. Children with monocular visual impairment (bootstrap estimate [95%CI] -0.05 [-0.08 to -0.01]) and binocular visual impairment (bootstrap estimate [95%CI] -0.09 [-0.11 to -0.07]) were more likely to have functional visual deficits than were normally sighted peers. CONCLUSIONS: Monocular or binocular visual impairment impacts on the functional vision of children in this rural population. Further studies are needed to determine the impact of treatment of visual impairment on functional vision in children of this population.

Mutation analysis of congenital cataracts in Indian families: identification of SNPS and a new causative allele in CRYBB2 gene.

PURPOSE: To study some functional candidate genes in cataract families of Indian descent. METHODS: Nine Indian families, clinically documented to have congenital/childhood cataracts, were screened for mutations in candidate genes such as CRYG (A-->D), CRYBB2, and GJA8 by PCR analyses and sequencing. Genomic DNA samples of either probands or any representative affected member of each family were PCR amplified and sequenced commercially. Documentation of single nucleotide polymorphisms (SNPs) and candidate mutations was done through BLAST SEARCH (http://www.ncbi.nlm.nih.gov/blast/Blast.cgi?). RESULTS: Several single nucleotide polymorphisms in CRYG, CRYBB2, and GJA8 genes were observed. Because they do not co-segregate with the phenotype, they were excluded as candidates for the cataract formation in these patients. However, a substitution (W151C in exon 6 of CRYBB2) was identified as the most likely causative mutation underlying the phenotype of central nuclear cataract in all affected members of family C176. Protein structural interpretations demonstrated that no major structural alterations could be predicted and that even the hydrogen bonds to the neighboring Leu166 were unchanged. Surprisingly, hydropathy analysis of the mutant betaB2-crystallin featuring the amino acids at position 147 to 155, further increased the hydrophobicity, which might impair the solubility of the mutant protein. Finally, the Cys residue at position 151 might possibly be involved in intramolecular disulphide bridges with other cysteines during translation, possibly leading to dramatic structural changes. CONCLUSIONS: Exon 6 of CRYBB2 appears to be a critical region susceptible for mutations leading to lens opacity.

PAX6 gene variations associated with aniridia in south India.

BACKGROUND: Mutations in the transcription factor gene PAX6 have been shown to be the cause of the aniridia phenotype. The purpose of this study was to analyze patients with aniridia to uncover PAX6 gene mutations in south Indian population. METHODS: Total genomic DNA was isolated from peripheral blood of twenty-eight members of six clinically diagnosed aniridia families and 60 normal healthy controls. The coding exons of the human PAX6 gene were amplified by PCR and allele specific variations were detected by single strand conformation polymorphism (SSCP) followed by automated sequencing. RESULTS: The sequencing results revealed novel PAX6 mutations in three patients with sporadic aniridia: c.715ins5, [c.1201delA; c.1239A>G] and c.901delA. Two previously reported nonsense mutations were also found: c.482C>A, c.830G>A. A neutral polymorphism was detected (IVS9-12C>T) at the boundary of intron 9 and exon 10. The two nonsense mutations found in the coding region of human PAX6 gene are reported for the first time in the south Indian population. CONCLUSION: The genetic analysis confirms that haploinsuffiency of the PAX6 gene causes the classic aniridia phenotype. Most of the point mutations detected in our study results in stop codons. Here we add three novel PAX6 gene mutations in south Indian population to the existing spectrum of mutations, which is not a well-studied ethnic group. Our study supports the hypothesis that a mutation in the PAX6 gene correlates with expression of aniridia.

A novel PAX6 gene mutation in an Indian aniridia patient.

PURPOSE: A mutation in the PAX6 gene is thought to be the genetic cause of aniridia. Here we search for PAX6 gene mutations in Indian aniridia patients. METHODS: We amplified the coding exons of the PAX6 gene from the genomic DNA of 15 unrelated aniridia patients using polymerase chain reaction technology. We then performed single-strand conformation polymorphism analysis and heteroduplex analysis to search for sequence variants. RESULTS: Sequencing of shifted bands in two patients revealed PAX6 gene mutations. One of these was a novel mutation, 1180insA, located in exon 10 at the start of the PST domain. The other mutation, 1080C->T (R240X), located in exon 9 within the homeodomain, and is another example of the most commonly reported PAX6 mutation. CONCLUSIONS: Although PAX6 gene mutations and polymorphisms have been reported from various ethnic groups, we report for the first time the identification of PAX6 gene mutations in Indian aniridia patients.

The Kariapatti pediatric eye evaluation project: baseline ophthalmic data of children aged 15 years or younger in Southern India.

PURPOSE: To estimate the prevalence of ocular morbidity among children of rural southern India before developing a service delivery model for community-based pediatric eye care. DESIGN: Population-based cross sectional study. METHODS: Trained field-workers performed door-to-door enumeration in 74 randomly selected villages of the Kariapatti block in southern India to identify children aged 15 years or younger and performed visual acuity measurements using Cambridge crowded cards and external eye examination with torchlight. Pediatric ophthalmologists further examined subjects with ocular problems identified by the field-worker. The clinical team performed repeat visual acuity measurements with Cambridge crowded cards, refraction, slit-lamp anterior segment examinations, and dilated posterior segment examinations at the screening site. The ophthalmologist identified and recorded one major cause for each visually impaired eye. RESULTS: Field-workers screened 10605 (94.6%) of 11206 children enumerated, and identified 1441 (13.6%) children as requiring further clinical examination. An additional 449 children identified as normal by the field-worker were randomly chosen for repeat examinations at the screening sites. In all, 1578 (83.5%) of these 1890 children were examined at the screening site. According to World Health Organization criteria, 6.2 of 10000 children were blind; 42.9% of this blindness was potentially avoidable. Refractive errors (0.55%, 95% confidence interval: 0.41, 0.69) and strabismus (0.43%, 95% confidence interval: 0.30, 0.55) were the major ocular morbidity in this population. CONCLUSIONS: Developing an appropriate service delivery model for this region will require a balance between the relatively low prevalence of morbidity and blindness and the need for service in this population.