Gaze-induced ONH deformations following eye movements are greater in high myopic eyes. Photo: Andrew Rouse, OD. Click image to enlarge.
It’s long been known that individuals with high myopia are at increased risk of glaucoma due the more challenging posterior segment anatomical circumstances brought about by long axial length. Researchers recently found that even simple eye movements put added strain on the lamina cribrosa and may contribute to an increased risk of glaucoma in such patients. They presented their results on the first day of ARVO 2023 in New Orleans.
The team used mathematical modeling and in vivo OCT imaging to estimate the effect of optic nerve traction on optic nerve head (ONH) deformations following horizontal eye movements, both in adduction and abduction in highly myopic eyes (axial length >26mm). To compare a model of an emmetropic eye with a longer axial length and thinner scleral thickness to represent changes in high myopia, the study imaged 16 eyes from nine patients with high myopia and 14 eyes from eight non-high myopia subjects. The eyes were imaged using OCT in primary gaze, 20° adduction and 20° abduction. A 3D strain algorithm measured lamina cribrosa strains for all loading scenarios.
ONH strains were greater in the high myopia vs. emmetropic finite element model during horizontal eye movements. On average, ONH deformations in adduction were higher than in abduction. Lamina cribrosa strains induced by adduction and abduction were both greater in the high myopia (0.051 and 0.037, respectively) vs. the emmetropic model (0.035 and 0.025). In human subjects, 3D strain tracking results showed lamina cribrosa strains were significantly greater in high myopia vs. non-high myopia eyes for both adduction (0.060 vs. 0.039) and abduction (0.039 vs. 0.025).
The researchers noted that clinicians should be aware of this possibility for increased risk for glaucoma in their myopic patients.
Original abstract content © Association for Research in Vision and Ophthalmology 2023.
Liu T, Wang YX, Hoang DQV, et al. Eyes with high myopia experience greater gaze-induced optic nerve head deformations compared to normal eyes. ARVO 2023 annual meeting.