Long-term Development of Significant Visual Field Defects in Highly Myopic Eyes

PURPOSE: To identify the characteristics that are associated significantly with visual field (VF) defects in highly myopic eyes. DESIGN: Retrospective, observational series. METHODS: The medical records of 492 eyes of 308 patients with high myopia (myopic refractive error > 8 diopters or axial length >= 26.5 mm) with a follow-up of 5 years or more were reviewed. The VFs were determined by Goldmann kinetic perimetry, and the VFs were quantified in 100 sectors within the V4 isopter. Eyes with loss of 10% or more of the sectors were classified as having significant VF defects, and a further loss of 10% or more during the follow-up period was classified as a significant progression. To avoid the influence of the posterior fundus changes resulting from the high myopia, eyes with any type of myopic macular or peripheral lesions that could cause visual field defects were excluded. RESULTS: Significant VF defects were newly developed in 13.2% of these selected highly myopic eyes during a mean follow-up standard deviation of 11.6 +/- 5.5 years. The incidence of significant VF defects in myopic eyes was significantly higher in eyes with an oval optic disc than that in eyes with a round optic disc. An oval optic disc was present significantly more frequently in the myopic eyes with VF defects. Temporal and nasal VF defects were present in the same eye. Among the eyes with significant VF defect, the temporal VF defects were observed in 61.5% of the eyes with round discs, in 75.0% of the eyes with vertically oval discs, and in 68.2% of the eyes with obliquely oval discs. During a mean follow-up +/- standard deviation of 10.2 +/- 3.4 years, 73.8% of the eyes showed a significant progression of the VF defects. An abrupt change of the scleral curvature (types VII and IX staphyloma by Curtin) was the only factor significantly associated with a progression of the VF defects. CONCLUSIONS: Because the VF defects are progressive, we suggest that high myopia is a high risk factor for VF defects and that these eyes be examined at least once yearly. The combination of stretching and distortion of the optic nerve fibers resulting from an abrupt change of scleral curvature may be the factors that lead to the damage of the optic nerve fibers in highly myopic eyes. (Am J Ophthalmol 2011;152:256-265. (C) 2011 by Elsevier Inc. All rights reserved.)