Pattern and magnitude of congenital and developmental cataract among children attending Muhimbili national hospital paediatric eye clinic

Background Congenital and developmental cataract affects children from birth up to 16 years of age. When cataract not treated on time can results in blindness or severe visual impairment in these children. Loss of vision in children has an impact in their education, employment and social life. This is the first study to be done in MNH paediatric eye clinic. This study is expected to provide baseline information on the pattern and magnitude of congenital and developmental cataract and to determine the prevalence of associated systemic anomalies among these children. Objectives: This study was designed to determine the prevalence, clinical presentation and etiologies of congenital and developmental cataract among children attending Muhimbili National Hospital Pediatric Eye Clinic. Methods: This was a cross sectional descriptive hospital based study, conducted from June 2009 to January 2010. During the period under study children referred from different parts of Tanzania with visual problems were screened for congenital and developmental cataract. Best corrected visual acuity was done according to the patient's age. Pupil dilation was done to facilitate better view of the lens morphology on slit lamp examination, cycloplegic refraction and fundoscopy where lens was less opaque. All children under study had their blood taken for rubella toxoplasmosis and HIV antibodies. SPSS version 15 was used for data entry, cleaning and statistical analysis. Results: A total of 1213 children from zero to 192 months of age were screened for cataract in MNH paediatric eye clinic whereby the overall prevalence of cataract was found to be 4.8%. Among 116 eyes of 58 patients 87% eyes were found to have cataract. Congenital cataract had a prevalence of 1.6% and developmental cataract 3.1 %. Majority 57.5% of children below 24 months of age were blind. Bilateral cataract was more common in both age groups 44 (75.9%). Most of these patients with unilateral and bilateral cataract had negative blood results for Vll rubella and toxoplasmosis antibodies. However those patients with positive blood results for rubella and toxoplasmosis had high prevalence of bilateral cataract. Congenital heart disease was observed in 3 patients with positive rubella antibodies. Thirty nine eyes were found to have lamellar cataract and 38.5% of these had moderate visual impairment. Among 116 eyes examined, 55 eyes were blind. Total cataract was the commonest morphological characteristic observed in 47 eyes. More than half of the patients 56.9% had undetermined causes of cataract. Conclusion This study has found that rubella and toxoplasmosis are still important causes of congenital and developmental cataract. This is of great concern in the prevention of these infections. These findings also highlight the effort of vision 2020 to focus on these infections in developing countries like Tanzania. The results from this study highlight that childhood cataract is an important cause of childhood blindness especially in the first 24 months of age