Wide-spread myelinated nerve fibers of the optic disc: do they influence the development of myopia?

PURPOSE

To find correlations between the extent of myelinated nerve fibers with refraction anomalies.

METHOD

Searching for myelinated nerve fibers in the slide collection of the University Eye Hospital Freiburg we found 13 patients. We distinguished between eyes with wide-spread myelinated nerve fibers located on and around the optic disc which extended to the midperiphery of the retina (6 patients; Group A) and eyes with circumscribed myelinated nerve fibers, localized merely around the optic disc (7 patients, Group B). In Group A myelinated nerve fibers spared the macula area, but were localized very close to the macula. Color fundus photographs were taken by the Zeiss Fundus camera SK50 (30 degrees and 50 degrees picture size) and by the Olympus Fundus camera GRC-W (same picture size).

RESULTS

The myelinated nerve fibers were found to be unilateral in all 13 patients. In all 6 patients of Group A, a strabismus was present. The affected eye had a severe amblyopia and a unilateral myopia (-5.75 to -25.0 D). The nonaffected fellow eye showed a normal visual acuity with no or only a slight refractive error. In the 7 patients of the Group B, no strabismus was present and a normal or a slightly decreased visual acuity of the affected eye was found. No distinct refractive error was present in the affected and non-affected eyes of this group.

CONCLUSIONS

Myopia only occurred in eyes with wide-spread myelinated nerve fibers but not in eyes with circumscribed myelinated nerve fibers. We assume that myelinated nerve fibers, if wide-spread, cause myopia.