Feasibility test of a new method to measure retinal thickness noninvasively.

There are many devastating ocular diseases that are directly related to an alteration of the retinal or nerve fiber layer thickness, such as glaucoma and macular edema. To diagnose these diseases earlier and to monitor their therapy more sensitively, an accurate measurement of the tissue thickness is needed. Since no clinical method is currently available, we developed and tested a new method capable of measuring noninvasively the retinal thickness. The separation between the images of the anterior and posterior intersections is quantitated by an optoelectronic system. The theoretical performance of the method has been calculated. Tests of the method in a model eye indicated that the measurements were basically diffraction limited, their reproductivity was +/- 9 microns, and their accuracy was 5.5 microns. Tests performed in vivo indicated that two intersections between the laser and the retina are present and correspond to the anterior and posterior surfaces of the retina. These intersections can be resolved and analyzed to yield quantitative data. These encouraging results indicate that this method is feasible and could yield sensitive measurements of the retinal thickness.