Case Series of Children Presenting with Unilateral Retinitis Pigmentosa
Carmel L. Mercado, MD; Shannon Beres, MD; Michael F. Marmor, MD; Scott R. Lambert, MD
Byers Eye Institute at Stanford
Palo Alto, CA
Introduction: Retinitis pigmentosa (RP) has only rarely been reported to be unilateral given its genetic etiology (1-2). Two potential mechanisms have been proposed: mosaicism or the presence of a somatic rather than a germline mutation (3). We present 4 cases with electroretinography (ERG) and imaging documentation.
Methods: We examined 4 children (1 male, 3 female, ages 9-15) referred for possible unilateral RP based on unilateral symptoms and fundus appearance. They underwent full-field ERG, optical coherence tomography, red-free imaging, and fundus photography and autofluorescence.
Results: Unilateral degeneration was found in 2 patients and 2 patients were diagnosed with highly asymmetric disease based on full-field ERG and longitudinal fundus exams (range 0.3-9.8 years). Full-field ERG showed severe unilateral decrease in amplitude and increased implicit time in the affected eye of all patients with unilateral disease. Autofluorescence in these eyes showed widespread lost fluorescence in the periphery and a hyperfluorescent macular ring demarcating the zone of partial foveal preservation. In the patients with asymmetric disease, the ERG revealed subtle abnormalities suggesting retinal degeneration in the fellow eye. Long term follow-up in one asymmetric patient showed patchy peripheral involvement although progression was difficult to assess; long term follow-up in one of the unilateral cases still showed no evidence of disease in the good eye.
Discussion: Functional testing and serial exams revealed subtle changes in the fellow eye of 2 of these 4 patients who all initially presented with unilateral signs and symptoms.
Conclusion: Childhood onset RP may occasionally be very asymmetric. True unilateral RP during childhood is rare.
References: 1. Marsiglia M, Duncker T, Peiretti E, Brodie SE, Tsang SH. Unilateral retinitis pigmentosa: a proposal of genetic pathogenic mechanisms. Eur J Ophthalmol. 2012 Jul-Aug;22(4):654-60. doi: 10.5301/ejo.5000086.
2. Farrell DF. Unilateral retinitis pigmentosa and cone-rod dystrophy. Clin Ophthalmol. 2009;3:263–70.
3. Mukhopadhyay R, Holder GE, Moore AT, Webster AR. Unilateral retinitis pigmentosa occurring in an individual with a germline mutation in the RP1 gene. Arch Ophthalmol. 2011;129:954–6.