الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 87 |  |  |
| | | from | 87 | | |
Abstract
Congenital aniridia is a rare condition related to a deficiency in the PAX6 gene expression, which may occur as a result of a family inheritance or a sporadic occurrence. The PAX6 gene encodes a transcription factor with multiple roles in the development of the eye and other tissues. It manifests as a total or partial absence of the iris caused most commonly by mutations in PAX6, FOXC1, PITX2, and CYP1B1. Recently two new genes, FOXD3 and TRIM44, have also been implicated in isolated studies. Classic aniridia is due to PAX6 mutations, while other genes contribute to aniridia-like phenotypes. Classic aniridia is a panocular condition, which includes aniridia, cataract, corneal pannus, foveal, and optic nerve hypoplasia associated with mutations in the PAX6 gene. . Most of the patients with aniridia present with foveal and/or macular hypoplasia since birth. The development of keratopathy, glaucoma, and cataract is frequent and or its presence has implications in the patient’s visual acuity.
The study was a retrospective chart review of children with aniridia that presented to and were examined in the pediatric ophthalmology practice of Alexandria Main University Hospital in the period from 2005 to 2020 reporting the ophthalmic features of these aniridic eyes. Forty-one children with aniridia were identified and their medical records were reviewed. The clinical examination data were complete for 67 eyes of which 17 (25%) were diagnosed as glaucoma in the initial visit. After a follow up of 1 year clinical examination data was completed for 39 eyes of which 14 (39%) were diagnosed as glaucoma and prescribed medical treatment (4 eyes) or subjected to glaucoma surgery (10 eyes). The standard glaucoma procedure in this study was a combined trabeculotomy-trabeculectomy with mitomycin C.
The study population demonstrates a slight female preponderance, and all study population has a bilateral condition (the 2 patients with reported one eye affected demonstrated atrophia in the other eye, and hence the data was not available). The age at presentation was the first 2-3 years of life. Longitudinal follow up data was available for only half of the study eyes, another limitation inherent to the retrospective study design. A C/D ratio of 0.4 – 0.5 raises suspicion of glaucoma especially if coupled with an elevated IOP and/or enlargement of the globe. However, the absence of these changes coupled with the stability of the C/D ratio over the 1 year of follow up of the study eyes (in the eyes in which these parameters were stable) is sufficient evidence of the absence of glaucoma. Glaucoma was diagnosed in the initial visit in 25% of the cases then in 39% of cases on subsequent follow up highlights the importance of follow up of children with aniridia for glaucoma and other complications. Reversal of optic nerve glaucomatous cupping with successful IOP control was found in our study population but the gradual increase of C/D ratio after the initial improvement reveals decline in this success of glaucoma surgery in aniridic children, especially in secondary glaucoma.
The mean IOP and biometric characteristics of aniridia eyes are not significantly different from the reported for age matched normal children’s eyes. Female children with aniridia have significantly longer eyes and thinner CCTs .Older children with aniridia have significantly thinner CCTs, larger C/D ratios, and higher IOPs.
Monitoring children younger than age eight years every four to six months for refractive errors and detection and treatment of incipient or actual amblyopia; annual ophthalmology follow up of all individuals to detect problems such as corneal changes, raised intraocular pressure, and cataracts. Glaucoma remains one of the most challenging features of aniridia. Eyes with aniridia usually develop glaucoma in late childhood or young adulthood, as progressive anatomical changes occur in the drainage angle. The incidence of glaucoma in aniridia on the first visit was 25% and of glaucoma suspects varied between 18% – 19% and at the last visit the incidence of glaucoma was 39% and of glaucoma suspects was 41%. The procedure of combined trabeculotomy-trabeculectomy with mitomycin C for glaucoma with aniridia has a success rate of 50% and results in a reduction of IOP that is sustained for at least 3 years.