This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Optics and Errors of Refraction, Subject name: Ophthalmology
[{'content': 'Minus cylinder lenses are prescribed because of \nSelect and explain. \nA. Cheaper to produce and distribute, B. Preferred due to meridional aniseikonia, C. Reduces minification, D. Causes less coma and trefoil', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Aniseikonia is defined as a condition wherein, images projected to visual coex from the two retinae are abnormally unequal in size and/or shape. Up to 5% aniseikonia is well tolerated. Meridional aniseikonia - refractive differences only occur in one meridian In a plus cylinder the lens is ground on the anterior surface of spectacle and thus there is more scattering and distoion of image as compared to a minus cylinder which is ground on posterior surface. Thus a minus cylinder is more comfoable to the patient and hence all prescriptions are written with a minus cylinder. Extra edge: - In pt with monocular aphakia wearing contact lens, % of aniseikonia is approximately 8% - In aphakia, Aniseikonia is decreased with contact lens than glasses. Hence, IOL implantation is preferred management NOTE- Aneisokonia with IOL- (1-3%)', 'role': 'assistant'}]