Functional Structure of the Retinal Fovea and Maxwell's Spot

Abstract

A REDDISH spot can be seen in the centre of the visual field when a white surface is viewed by a normal observer through a dichroic filter transmitting red and blue lights. This phenomenon is called Maxwell's spot and interpreted usually as an entoptic phenomenon due to preferential absorption of blue light in macular pigment. Among various types, the commonest is of symmetrical circular form and is made up of three concentric zones: a spot, a clear ring and a halo, going from the centre to the outside^l,2. The central spot and the halo are reddish, and the clear ring has the same chromatic quality as the background field, which is bluish-red in most cases.