<prompt> A young patient presented with sudden painless loss of vision with systolic murmur over chest, ocular examination reveals - cherry red spot in macula with clear AC, with perception of light, diagnosis:Central retinal aery occlusionCentral retinal vein occlusionMacular choroiditis with infective endocarditisCentral serous retinopathy  <response>: A i.e. Central retinal aery occlusion All the above can lead to sudden painless loss of vision, but Cherry-Red Spot is seen only in CRAO Sudden Painful Painless Acute Macular edema congestive CRAO Q central retinal aery angle occlusion closure CRVO Q central retinal vein occlusion glaucoma Q Central serous retinopathy Acute Retinal detachment Q iridocyclitis Exudative Age Related Macular uveitis Q Degeneration ARMD Chemical Vitreous retinal haemorrhage eg mechanical Eales disease Q injury to Optic neuritis Q eyeball Methyl alcohol amblyopia Subluxation or dislocation of lens Gradual Painful Painless Corneal Progressive pterygium ulceration Corneal dystrophy Chronic Corneal degeneration simple Cataract Q developmental senile glaucoma Chorioretinal degeneration Chronic Dry type - Age related macular iridocyclitis degeneration ARMD Q uveitis Diabetic retinopathy Q Retinitis pigmentosa Q Optic atrophy Q Refractive errors Preshyopia Cherry Red Spot Macula is situated at posterior pole with its centre foveola being about 2 disc diameters lateral to temporal margin of disc. When retina becomes milky white due to edema, central pa of macular are shows cherry red spot due to vascular choroid shining through the thin retina of this region. Cause are:- 1. Quinine amblyopia 2. Niemann-Picks diseaseQ 3. Metachromatic leukodystrophyQ 4. Multiple sulfatase deficiencyQ 5. Taysachs diseaseQ GM2 gangliosidosis type 1 6. Berlins oedema Commotio retinaeQ due to blunt blow on eye 7. Central Retinal Aery occlusion CRAOQ not in CRVOQ 8. Gauchers diseaseQ, Goldberg syndrome 9. Generalized gangliosidosis Gml gangliosidosis type 1Q 10. Sandhoff disease Gm2 gangliosidosis type 2, sphingolipidosis 11. Sialidosis type 1 2 cherry red spot myoclonus syndrome, sphingolipidosis 12. Farbers disease 13. Hurlers syndrome Mucopolysaccharidosis 1H, HallervordenSpatz disease 14. Mucopolysachharidosis VII 3 galactosidase deficiency 