A young man presented to you with night blindness and tubular vison. On examination the findings are IOP is 18mm, normal anterior segment, fundus examination shows waxy, pallor of disc, attenuation of aeriole, bony corpuscles like spicules of pigmentation in midperipheral retina. Perimetry test shows a ring scotoma with subnormal ERG. What is the your most likely diagnosis?

Patient in the question is showing features of retinitis pigmentosa, which is a primary pigmentary retinal dystrophy affecting the rods more than the cones. Examination of fundus in this condition shows pigmentary changes typically perivascular and resembling bone corpuscles, attenuation of retinal aerioles and pale and waxy optic disc. Visual field changes includes annular or ring shaped scotoma and finally a tubular vision. Electroretinogram initially shows decreased scotopic response later followed by a decreased photopic response. Ref: Comprehensive Ophthalmology By A K Khurana, 4th Edition, Page 269