###Rationale: 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

###Answer: OPTION D IS CORRECT.
###Question: Aniseikonia refers to
###Options:
A. Difference in the refractive power
B. Difference in the corneal diameter
C. Difference in image colour
D. Difference in the retinal image size
