Abstract
Purpose :
To quantify accommodative movements of the lens and choroidal movements in the human eye and the anterior hyaloid movements in the monkey eye, to determine if they are related to accommodative amplitude and presbyopia.
Methods :
In eyes of 4 rhesus monkeys (aged 8-19 yrs), accommodative responses were induced by central electrical stimulation of the midbrain in a dose-dependent manner, from minimal to maximal accommodative responses. Accommodation was induced in the human eye by 4% topical pilocarpine. Accommodative amplitude was measured by Hartinger coincidence refractometry. OCT and ultrasound biomicroscopy (UBM; 50, 20 MHz) images were collected in the region of the lens, ciliary body and over the entire extent of the globe in monkey and human subjects in resting and accommodated states.
Results :
Monkey: In this preliminary study, accommodative anterior hyaloid posterior movement was significantly related to accommodative amplitude in all 4 animals thus far measured (the more the anterior hyaloid moved posteriorly during accommodation, the higher the accommodative amplitude) but the relationship changed with age. In the young eye the average slope of the regression equation was 44.2 ± 5.5 diopters/mm (p= 0.001, n=2), but in the older eye it was 16.02 ± 3.23 diopters/mm (p= 0.007, n=2). Human: Lens accommodative thickening was significantly related to accommodative amplitude (26.02 ± 3.28 diopters/mm, n=22) but the relationship changed with age; young = 12.5 ± 6.6 diopters/mm (p=0.08, n=14); older = 3.72 ± 3.65 diopters/mm (p=0.35, n=8). In the older eye accommodative centrifugal choroidal movement around the optic nerve was negatively correlated with accommodative amplitude; the more centrifugal choroid movement the less accommodative amplitude (-0.63 ± 0.11 mm/diopter, p=0.028, r=0.97, n=4). Choroidal thinning was positively correlated with accommodative amplitude; the more the choroid thinned the higher the accommodative amplitude (43.5 ± 9.2 µm/diopter, p=0.042, r=0.96, n=4).
Conclusions :
There are statistically significant accommodative movements of the choroid and various intravitreal structures. The posterior anterior hyaloid and choroidal movements may provide insights to the mechanism of accommodation, presbyopia, accommodating IOL function and perhaps glaucoma.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.