High symmetry of visual acuity and visual fields in RPGR-linked retinitis pigmentosa by Bellingrath, J-S, Ochakovski, GA, Seitz, IP, Kohl, S, Zrenner, E, Hanig, N, Prokisch, H, Weber, BH, Downes, SM, Ramsden, S, MacLaren, RE, Fischer, MD