<prompt> What is the cause of glaucoma in retinoblastoma?Blockge of trabecular networkNeovascularisationMass effect of the tumourLysis of the lens  <response>: Ans. is b i.e., Neovascularisation Neovascular glaucoma Rubeosis iridiso It is a secondary angle closure glaucoma which results due to formation of neovascular membrane over the iris i.e., neovascularization of iris rubeosis iridis.o Causes of rubeosis iridis arei Common Diabetic retinopathy most common cause, central retinal vein occlusion Eales disease, sickle-cell retinopathy.ii Rare causes: - Long standing retinal detachment, central retinal artery occlusion, intraocular inflammation uveitis, intraocular tumors choroidal melanoma, retinoblastoma, radiation retinopathy, ocular ischemic syndrome carotid ar tery disease, carotid - cavernous fistula, Fuschs heterochromic iridocyclitis. 