Infantile cataracts

Profile of congenital cataract in the first year of life from a tertiary care center in South India - A modern series

Purpose:

To report the etiology, clinical presentation, and morphology of congenital cataract in a tertiary care center.

Methods:

It is a prospective cohort study conducted at L V Prasad Eye Institute, Hyderabad. All children with congenital cataract ≤ 12 months of age that required surgical intervention between August 2015 and July 2016 were included in the study. 109 such patients were subjected to meticulous history taking, pedigree charting, ocular, and systemic examination, B-scan, TORCH testing, clinical photographs, pediatrician consult and blood tests, which included serum calcium, serum phosphorous and urine for reducing sugars.

Results:

The mean age of presentation was 4.1 months (±2.6 months) and both the genders were equally affected (P = 0.49). Eighty-five patients (77.9%) presented with bilateral cataracts while 24 patients had a unilateral presentation (22.1%). The common morphological presentation was either a total or a nuclear cataract, both variants noticed in 47 patients (43.1%). TORCH infections were responsible for a maximum (37 patients, 33.4%) number of cases followed by familial (20 patients, 18%) and developmental anomalies (11 patients, 10.1%) while the total number of idiopathic cases were 24% (27 patients). Eighteen patients (16.5%) had congenital heart defects and the majority (16 patients, 88.9%) of these had positive TORCH titres.

Conclusion:

Familial cataract and those possibly due to TORCH are still the predominant cause of congenital cataract in this series-highlighting the role of vaccination and preventive measures.

An increase in apoptosis and reduction in αB-crystallin expression levels in the lens underlie the cataractogenesis of Morioka cataract (MCT) mice

We examined the morphological changes in fibers, localization of apoptotic cells, and protein expression of αB-crystallin in the lens of Morioka cataract (MCT) mice, a novel cataract model. Using a scanning electron microscope, swollen lens fibers and enlarged spaces between lens fibers were observed in the lens of 3-week-old MCT mice. At 2 weeks of age (before cataract), the single-strand DNA (ssDNA)-positive (indicating apoptosis) cell ratio of the lens epithelium was significantly higher in MCT than in wild-type ddY mice. At 2 and 4 weeks of age, αB-crystallin protein expression of the lens in MCT mice was significantly lower than that in wild-type ddY mice. These findings suggest that increase in apoptosis and reduction in αBcrystallin level are involved in the cataractogenesis of MCT mice.

Novel cataract mouse model using ddY strain: hereditary and histological characteristics

A novel cataract model was identified in the ddY strain (outbred colony) reared at Osaka Prefecture University. Opacity appeared as a white pinpoint focus in the unpigmented eyes of cataract mice at 6 weeks of age. All mice, fully viable and fertile, were bilaterally affected by the time they were 10 weeks of age. There were no gender differences in the incidence of cataracts. Histologically, 5-month-old cataract mice showed vacuolation of epithelial cells, disruption of lens fibers, and dislocation of the lens nucleus to the posterior lens cortex. To elucidate the mode of inheritance, heterozygous mutant hybrids between cataract mice and wild-type ddY mice, as well as offspring between the heterozygous mutants, were analyzed. No affected mice were observed among the heterozygous mutants, and the ratio of affected to unaffected mice was 1:3 among offspring between heterozygous mutants. For linkage analysis, we produced backcross progeny [cataract mouse x (cataract mouse x MSM/Ms mouse)], and concluded that the cataracts are inherited by an autosomal recessive gene. Moreover, the locus of the cataract gene, mct, was mapped to the 3.91 cM region encompassed by D2Mit467 and D2Mit320 on mouse chromosome 2 by linkage analysis. Thus, the present cataract mice represent a novel cataract mouse model, and have been designated Morioka cataract (MCT) mice.

[Examination methods in the diagnosis of uni- and bilateral cataracts in childhood]

Today, the management of congenital and developmental pediatric uni- and bilateral cataract is still a problem, particularly because untreated lens opacity has a high amblyogenic potential. Such irreversible deprivation amblyopia in pediatric cataracts requires an early diagnosis. Due to the increased inflammatory reaction postoperatively, a minimally traumatic operation, intensive occlusion therapy and optimal correction with glasses or contact lenses are also necessary. Uni- and bilateral cataracts and their preoperative diagnostics have to be considered separately.

Cataracts in children

Bilateral congenital cataract is the most common cause of treatable childhood blindness. Nuclear cataract is usually present at birth and is nonprogressive, whereas lamellar cataract usually develops later and is progressive. Surgery must be performed promptly in cases with dense congenital cataract; if nystagmus has developed, the amblyopia is irreversible. A treatment regimen based on surgery within 2 months of birth combined with prompt optical correction of the aphakia and aggressive occlusion therapy with frequent follow-up has been successful in unilateral and bilateral cases. Both anterior and posterior capsulorhexes are performed in most children. Intraocular lens implantation can be performed safely in children older than 1 year. Anterior dry vitrectomy is recommended in preschool children to avoid after-cataract. Opacification of the visual axis is the most common complication of cataract surgery in children. Secondary glaucoma is the most sight-threatening complication and is common if surgery is performed early. Life-long follow-up is essential in these cases.

Bilateral congenital cataracts result from a gain-of-function mutation in the gene for aquaporin-0 in mice

Cataract Tohoku (Cat(Tohm)) is a dominant cataract mutation that leads to severe degeneration of lens fiber cells. Linkage analysis showed that the Cat(Tohm) mutation is located on mouse chromosome 10, close to the gene for aquaporin-0 (Aqp0), which encodes a membrane protein that is expressed specifically in lens fiber cells. Sequence analysis of Aqp0 revealed a 12-bp deletion without any change in the reading frame, which resulted in a deletion of four amino acids within the second transmembrane region of the AQP0 protein. Targeted expression of the mutated Aqp0 caused lens opacity in transgenic mice, the pathological severity of which depended on the expression level of the transgene. The mutated AQP0 protein was localized to the intracellular and perinuclear spaces rather than to the plasma membranes of the lens fiber cells. The cataract phenotype of Cat(Tohm) is caused by a gain-of-function mutation in the mutated AQP0 protein and not by a loss-of-function mutation.

Results of bilateral cataract extraction with posterior chamber intraocular lens implantation in children

OBJECTIVE

A retrospective study was undertaken to evaluate long-term anatomic and visual outcomes in eyes of children who underwent bilateral intraocular lens implantation.

DESIGN

The study design was a review of medical records of 24 children operated on for bilateral cataracts and posterior chamber-intraocular lenses.

PARTICIPANTS

Twenty-four children operated on for bilateral cataracts by 1 surgeon between February 1980 and February 1995 were studied.

INTERVENTION

Cataract extraction with bilateral posterior chamber-intraocular lens implantation was performed.

MAIN OUTCOME MEASURES

Best-corrected visual acuity, visual acuity without correction, intraocular pressure, manifest refraction, and any intraoperative or postoperative complications were measured.

RESULTS

At last follow-up (mean follow-up, 50.8 months; range, 10-149 months), the intraocular lens was in good position and the intraocular pressure was normal without medication in all eyes. Four years after surgery, 79.2% (19 of 24) of first eyes achieved a best-corrected visual acuity of 20/40 or better compared to 66.7% (16 of 24) of second eyes. No eye had any loss in best-corrected visual acuity. In first eyes of 3- to 8-year olds at the time of surgery, 73.3% (11 of 15) achieved a spherical equivalent within 2 diopters of the intended at 4 years after surgery compared to 80% of second eyes. In the 9- to 18-year-old group, 88.9% (8 of 9) of first eyes and 100% of second eyes achieved a spherical equivalent within 2 diopters of the intended at 4 years after surgery. Intraoperative and postoperative complications were minimal.

CONCLUSIONS

Long-term anatomic and visual results have been gratifying in this series of patients with bilateral implants.

Genetic mapping of a mouse ocular malformation locus, Tcm, to chromosome 4

The Tcm mutation in the mouse is an autosomal dominant ocular malformation manifesting as microphthalmia, iris dysplasia, cataract, and coloboma. As a first step to cloning the Tcm gene, we report the localization of the Tcm mutation with respect to known microsatellite markers. Backcross progeny carrying the Tcm mutation were produced by mating Tcm/+ heterozygous mice to normal C57BL/6 partners. Genomic DNA from each mouse was subjected to PCR analysis to identify simple sequence length polymorphisms. Our results locate Tcm to Chr 4 and suggest candidate genes responsible for the Tcm phenotype. Finally, ocular histopathology was done in 3-week-old animals to define the extent of the malformation.

Cloudy lenses and issues: a pedigree of unoperated congenital cataracts

The issue of when congenital cataracts should be removed seems to be well resolved, with most recommendations stating that all significant central lens opacities should be removed by 4 months of age, with removal most commonly occurring the first month. Although there are many strong recommendations regarding congenital cataracts in the literature, little has been written about the initial decision of whether or not to operate. A pedigree is presented of multiple generations with inherited bilateral central cataracts. Two affected children, who did not undergo surgery, were followed from birth. These two children developed essentially normal vision, despite seemingly significant central opacities. This pedigree emphasizes the need to further examine prognostic factors regarding bilateral infantile cataracts and to analyze the initial surgical decision. Because this condition does not often occur and a large number of patients is necessary to determine the predictive value, a large, collaborative study is required to make significant headway in this area. If we can identify the factors that have strong predictive value for good vision after cataract surgery, we may start to define the profile of children who will have good vision, with or without surgery.

Pediatric cataracts

The presentation, etiology, diagnostic examination, and management of pediatric cataracts are discussed in this article. If untreated, cataracts result in significant visual deprivation. Evaluation of the pupillary light reflex should become an integral part of every pediatrician's physical examination. Patients should be referred for a complete eye examination whenever a cataract is suspected because early intervention may be the most important factor in determining a good visual outcome.