Conjunctivitis It is caused by virus and bacteria, it is also caused by allergy. Glaucoma narrow or blocked angle of anterior chamber. Corneal Ulcer Bacteria, virus, fungus. Iritis Endogenous & exogenous causes. Cataract Due to old age, trauma, genetic, nutritional, UV-rays. Refractive Errors Due to small or large eye ball and abnormal curvature of cornea. Trachoma Chlamydia organisms. Retinopathy Affects the retina due to diabetes and hypertension. Squint Refractive error/nerve palsy. Night Blindness Deficiency of vitamin A/retinitis pigmentosa. Corneal Opacity Injuries to cornea, vitamin A deficiency.