This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Degenerative Conditions, Subject name: Ophthalmology
[{'content': 'Pterygium causes visual disturbances due to: \nSelect and explain. \nA. Astigmatism, B. Myopia, C. Hypermetropia, D. Keratoconus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref: Basak Essentials of Ophthalmology 5th edition pg no 153 -156Explanation:PterygiumElastotic degeneration of the subconjunctival tissue which proliferates as a triangular fold of tissue to invade the cornea.Etiology:Idiopathic.Exposure to UV raysHot sandy weather are risk factorsPingecula may be a precursorSymptoms:Appearance of a massDefective vision - Due to astigmatism f with the rule astigmatism] & obstruction of the papillary area by the tissue invasionDiplopia - due to symblepliaron causing restricted ocular movementsSigns:Most common on the nasal side.Double Pterygium - When pterygium is seen on both nasal & temporal sideThree PartsHead - apex of the triangular mass.Neck - constricted portion at the limbus,Body - the remaining bulky part & cap - infiltration in front of the head."Stocker\'s line"- iron deposit infront of cap in the corneal epithelium.Stages:Progressive - fleshy, thick with prominent vascularity, gradually increases in size. Cap is presentAtrophic - Thin, attenuated with poor vascularity. Stationary.Management: Pterygium excision with conjunctival autograft/ amniotic membrane graft', 'role': 'assistant'}]