Ocular Characteristics of Patients with Retinitis Pigmentosa in Ibadan, South West Nigeria

Abstract

Introduction: Retinitis pigmentosa (RP) is an inherited retinal disease affecting the photoreceptors.1 RP is thought to be rare with a prevalence of 1 in 4000 worldwide. 3 In Nigeria, the prevalence from hospital-based studies varies from 0.31% to 0.69%. 3-7 The classic triad of clinical signs in RP include bone spicule pigmentation, waxy pale disc and attenuated vessels. 1 Varying ocular disorders such as myopia, glaucoma, cataracts, optic disc drusen and keratoconus may be associated with RP.7.8Nyctalopia and constrictedvisual fields occur in RP. Visual impairment may be a debilitating sequelae.2The aim of this study was to describe the ocular features of patients presenting with RP at the retina clinic of the University College Hospital, Ibadan, Nigeria.

Methods: A retrospective study of all patients with clinical diagnosis of RP seen in the retina clinic of the University College Hospital, Ibadan, Nigeria from January 2018 to June 2022. The demographic data, best corrected visual acuity,
presenting complaints and other relevant information were retrieved from patients’ notes. Statistical analysis was done with SPSS Version 23.

Results: Forty-six (2.4%) of 1911 new patients seen during the study periodat the Retina clinic had a diagnosis of RP. Forty-three patients who had the necessary complete data were studied. Twenty- four (54.8%) of the patients studied were males while 19(44.2%) were females. The male to female ratio was 1.3:1. Sporadic mode of inheritance was the most common and was seen in 60.5% of the patients (Figure 1). Features of typical RP were found in 78.6% of the patients. The predominant complaint was poor vision which was present in 40 (93%) patients (Table 1). Night blindness was the initial complaint in 26 patients (60.5%). Thirty-one (72.1%) patients had visual impairment. In RP patients with visual impairment, maculopathy was the commonest aetiology. Bone spicule pigmentation (Figure 2) was present in all
patients with typical RP (78.6%). The commonest refractive error was myopia which was present in 34 eyes (39.5%). Thirty-three (38.4%) eyes had cataracts while features of glaucoma was presentin 1 (4.7%) patient. The best corrected visual acuity (BCVA) in 26 (30.2%) of all eyes studied was >6/18.

Conclusion: The prevalence of RP in this study was higher than previous figures ranging between 0.31% and 0.69% from similar studies from various parts of Nigeria.3-7 A male preponderance was noted and this is similar to other studies but
differed from a report from Cameroon.9 The mean age was identical to what was obtained in a study in Onitsha3 but lower than other recent multicenter studies in Nigeria.5,7Poor vison was the commonest presenting complaint akin to findings in Benin city.6 Prevalence of visual impairment noted was similar to other local studies in Nigeria.3,7 There was a
high prevalence of cataracts and low rate of glaucoma comparable to findings in China but differing from other studies. 5,9,10 RP is a common inherited retinal disease in our populace. There is an increasing prevalence possibly attributable to
increased patient awareness. Molecular and genetic studies are important tools in accurate diagnosis of these patients.