Retinal cartography. An analysis of two-dimensional and three-dimensional mapping of the retina.

The current two-dimensional (2D) retinal drawing chart is an azimuth equidistant representation of the retina. The distortion produced by this chart was analyzed and compared to other 2D projections, such as stereographic, equal area, and orthographic maps of the retina. Circumferential distortion was calculated for lesions at varying distances from the macula using the azimuth equidistant retinal map and was found to increase exponentially as a function of the distance from the macula. Circumferential distortion was 57.1% at the equator, 88.5% 3 mm anterior to the equator, and 137.8% 6 mm anterior to the equator. A three-dimensional (3D) model of the retinal surface was created using 3D computer assisted design (CAD) software. This 3D model was able to represent retinal lesions such that their true size, shape, location, and orientation were all conserved. Retinal lesions could be viewed from multiple angles and examined in cross section. The use of 3D CAD software coupled with ultrasound or magnetic resonance imaging data has the potential to represent retinal lesions more accurately than current methods.