Localized retinal nerve fiber optic nerve atrophy

Glaucomatous optic nerve atrophy is morphologically characterized by intrapapillary changes such as a loss of neuroretinal rim, parapapillary alterations such as an enlarged parapapillary chorioretinal atrophy, and changes in the retinal nerve fiber layer (RNFL) [1-3]. These include a diffuse loss with a generalized decreased visibility of the retinal ganglion cell axons and a localized type of damage with sharply demarcated wedge-shaped defects. The latter, occurring very rarely in normal eyes, have high specificity for optic nerve damage [3]. This study was performed to evaluate whether these localized R N F L defects are pathognomonic for glaucoma or can also be found in other types of optic nerve atrophy. Wide-angle red-free R N F L photographs of 222 eyes with nonglaucomatous optic nerve damage were examined. The mean age of the patients was 47.4__ 19.0 years (range 8-84 years) and the refractive error averaged 0.4 + 2.3 Di. The patients were part of an ongoing prospective study on the biomorphometry of the optic nerve involving all those patients coming to the hospital with an optic nerve anomaly or disease. The optic nerve atrophy was caused by intraocular diseases such as toxoplasmotic retinochoroiditis, optic disc changes such as disc drusen, and extraocular factors such as intracranial tumors. We used a 60 ° fundus camera, high-power illumination, a blue filter and a low-sensitivitiy film with high resolution. Instead of paper prints, dapositives were developed. Mixed with the diapositives of more than 300 glaucoma patients and 200 normal subjects, the slides were projected with a magnification of 15 times after maximal defocusing of the projector. The area of the blurred image of the optic disc was covered, then the projector was refocused and the R N F L evaluated. A localized defect was defined as a wedgeshaped and not spindle-like defect, running towards or touching the optic disc border for not more than 60 ° of the optic disc circumference.