This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Optics and refraction, Subject name: Ophthalmology
[{'content': 'Aniseikonia refers to \nSelect and explain. \nA. Difference in the refractive power, B. Difference in the corneal diameter, C. Difference in image colour, D. Difference in the retinal image size', 'role': 'user'}, {'content': 'Answer: D \nExplanation: ANISEIKONIA Aniseikonia is defined as a condition wherein the images projected to the visual coex from the two retinae are abnormally unequal in size and/or shape. Etiological types: 1. Optical aniseikonia: may occur due to either inherent or acquired anisometropia of high degree. 2. Retinal aniseikonia: may develop due to displacement of retinal elements towards the nodal point in one eye due to stretching or oedema of the retina. 3. Coical aniseikonia: implies asymmetrical simultaneous perception inspite of equal size of images formed on the two retinae. Symptoms : 1. Asthenopia, i.e., eyeache, browache and tiredness of eyes. 2. Diplopia due to difficult binocular vision when the difference in images of two eyes is more than 5 percent. 3. Difficulty in depth perception. Figure : Schematic presentation of the ocular sources determining aniseikonia and the visualization of a visual field angle a (for simplicity the optical and visual axis are assumed equal here). Reference :- A K KHURANA; pg num:-39', 'role': 'assistant'}]