Evidence for transient forces/strains at the optic nerve head in myopia: repeated measurements of the Stiles–Crawford Effect of the First Kind (SCE‐I) over time

Abstract

Probable transient changes in photoreceptor alignments, inferred from the measurements of the Stiles-Crawford effect of the first kind (SCE - I), were demonstrated in myopic eyes with elongated axial length (regardless of the magnitude of refractive error) at three retinal locations; the fovea (point of fixation), and 22 degrees and 27 degrees in the nasal retina. The changes were much bigger at 22 degrees and 27 degrees in the nasal retina (which are located beyond the optic nerve head) than at the fovea. These transient effects were revealed by repeatedly testing the same retinal locations over a period of time. Time intervals between the subsequent/repeated measurements ranged from less than an hour to several months. In some locations, the changes were recorded in less than an hour. Collectively, these were very meaningful changes. Generally bigger effects were recorded in the horizontal SCE - I than in the vertical SCE - I.

Influences of accommodation and myopia on the foveal Stiles–Crawford effect

“…Fluctuations in photoreceptor alignment have been demonstrated in eyes with elongated axial lengths, whether myopic or emmetropic, by repeatedly testing three retinal locations (the fovea, and 22 and 27 in the nasal retina) over a period of time [25], with the authors suggesting that the cause of these were mechanical forces originating near the optic nerve head in long eyes.…”

The Human Eye and Adaptive Optics

“…Delayed recovery of photoreceptor directionality was found when measuring SCE at a stage of the disease when no abnormalities were found using other common diagnostic techniques such as VA and optical coherence tomography (OCT). Transient changes of the SCE have also been found in the near periphery of myopic eyes with elongated axial lengths (Choi et al, 2004) and in eyes with permanent visual field loss and damage of the inner retinal layers secondary to optic neuropathies .…”

Traction centered nasal to the optic nerve head in high myopic observers

“…Here, we tested the SCE-1 at 22 in the Temporal Visual Field (TVF) [17]. This test locus lies on the horizontal raphe´a bit nasal on the retina relative to the disc.…”

“…The magnitudes of measured receptor orientation changes remain greatest just nasal to the optic nerve head (or disc) and decrease slowly with increasing distance from this apparent locus in all radial directions across the posterior pole of the eye, see e.g. [3,17,18]. In a separate study, this apparent effect was differentiated from strains induced by vitreous body adhesions to the retina and optic nerve head [19].…”