Abstract
Abstract: :
Purpose: Characteristic alterations in retinal photoreceptor alignments were studied in mid to higher range myopic observers and in some normal observers with large/long eyes and flat corneas.1-5 These anomalous orientations were revealed by tests of the SCE-I. Such orientations were found in a region about the optic nerve head. They were greatest on the retina nasal to the disc, less temporal, above and below the disc. In higher myopes, they extend to the foveal area. Both stable and transient anomalies were found. Methods: The SCE-I was mapped in a number of myopes of different degrees, and normals to characterize better the extent and magnitude(s) of these anomalies. Testing was conducted at the following locations: fixation (0º); 5º, 10º, 15º in the nasal visual field (NVF); 5º, 10º, 22º, 27º in the temporal visual field (TVF); 16º/5º & 16º/10º in the inferior/temporal visual field; 16º/5º in the superior temporal visual field. All observers had 20/30 corrected vision or better in eyes reported. Informed consent was obtained. Results: Data were consistent with prior findings. Characteristic patterns of anomalous orientations were found in myopes, with more extensive effects and greater anomalies of alignment detected in higher myopic observers. In affected eyes, SCE-I peaks tended to point more towards the disc, i.e. nasal tilting of receptors at 10º TVF and temporal tilting at 22º and 27º TVF. Normal eyes exhibited characteristic center-of-the-exit-pupil-alignment at all tested retinal loci. A subset of "normal" eyes with long/large globes and flat corneas exhibited SCE-I data similar to myopes. Conclusion: Further evidence of tractional strains on photoreceptors about the optic nerve head was found in myopes and certain normals. The misorientations of receptors over-rode characteristic alignment with the center-of-the eye-pupil found in true normals. The anomalous effects were highly correlated with axial length of the eye and magnitude of the myopia. References: 1,2. IOVS 41(4): S431, 2000; 3,4. IOVS 42(4): S163, 2001; 5. Enoch, J, et al, in Perimetry Update 2000/2001, eds. M. Wall & R.P. Mills, The Hague, The Netherlands, Kugler Pub., 2001, 373-387. Research supported, in part, by the New Del Amo Research Program. None.
Keywords: 517 photoreceptors • 481 myopia • 554 retina