Name

Distribution et causes de cécité et déficit visuel sévère pédiatrique dans un centre de référence au Rwanda

To determine the prevalence and the causes of severe visual impairment and blindness (SVI/BL) in children at a tertiary referral centre in Rwanda

In this retrospective study, files of all patients <18 years presenting during the year 2019 at the Kabgayi Eye Unit in Rwanda with SVI/BL (presenting visual acuity of <6/60 Snellen or lack of preferential looking behaviour) in at least one eye were analysed for age, sex, laterality, province of origin and cause of SVI/BL. Causes were categorized according to WHO standard classification. 

Out of 3939 children presenting to the clinic, 428 (10.9%) had SVI/BL in at least one eye. 165 (4.2%) patients had bilateral and 263 (6.7%) had unilateral condition. Of patients with BL/SVI, 36.7% were below the age of 6 years. In bilateral BL/SVI the main causes were cataract (18%), refractive error (18%), keratoconus (13%), congenital eye anomaly (9%), glaucoma (8%), cortical blindness (8%) and retinoblastoma (6%). In unilateral BL/SVI it was trauma (46%), cataract (8%), keratoconus (8%), infectious corneal disease (7%) and retinoblastoma (7%). In preschool children, retinopathy of prematurity accounted for 7% of bilateral BL/SVI. Avoidable BL/SVI accounted for 87% of all cases

In our study, nearly two third of the patients presenting with BL/SVI were boys. A similar observation was made in previous studies on blindness in childhood. 

The most common aetiologies for bilateral disease were cataract, refractive error and keratoconus with a clear difference in aetiologies between the two age groups. Preschool children had, expectedly, a higher rate of congenital eye anomaly, cataract, glaucoma, retinoblastoma and ROP whereas schoolchildren had a higher rate of keratoconus, cataract and refractive error. 

For unilateral disease the most common aetiologies were trauma, cataract, keratoconus and infectious corneal ulcer. In both age groups, trauma was the main cause of unilateral BL/SVI. For preschool children it was followed by retinoblastoma whereas for school children it was followed by keratoconus and cataract. 

Interestingly, the lack of school children blind to ROP and cortical blindness contrasts with a high prevalence in preschool children. This may suggest a changing pattern of BL/SVI secondary to the improvement of neonatal care and the survival of more and younger preterm children. 

Overall our results suggest a BL/SVI pattern with aspects of a middle-income country with ROP emerging as a new cause of bilateral blindness (4% of bilateral cases) and a high rate of cataract (18% of bilateral cases) and glaucoma (8% of bilateral cases), though aspects of a low-income country remain with congenital eye anomaly and infectious corneal opacity accounting for 13% of bilateral cases.

A different pattern of causes observed between preschool and school children suggests an increase in blindness associated with higher survival of premature and complicated birth. The high number of avoidable causes for SVI/BL may be reduced through several cost-effective ways.