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Carol Toris, Sangeetha Raghupathy, George Tye, Alia Baig, Thomas Stokkermans; How accommodative changes can affect intraocular pressure and ocular biometrics. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2715.
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This study investigates how conscious changes in accommodation (CM exercises), can affect intraocular pressure (IOP) and ocular biometrics in healthy adult volunteers of different ages.
Thirty-five healthy volunteers with phakic eyes and refractive errors between -3D and +2D were stratified by age into 20, 40, and 60 year-old (yo) age groups. Biometric measurements of central cornea thickness, anterior chamber depth, anterior chamber angle and pupil size were made by autorefraction and OCT imaging. IOP was measured by pneumatonometry. Next, each subject fixated on a target 40 cm away through lenses that induced non-accommodating (0 diopters) or accommodating (3 diopters) states in the right eye. Three different 10-minute tests were performed by switching lenses – A. non-accommodating, B. accommodating, and C. alternated between accommodating and nonaccommodating every minute for the 10 minutes. The order of tests was randomized. Between tests, the subject was given a 20-minute rest. Data from 31 subjects were included in the analysis. The investigators analyzing the data and images were masked as to age group or test. Statistical tests included ANOVA, and paired t-tests.
Combining all age groups, IOP (mmHg) decreased significantly with the alternating accommodation test (17.7±3.3) when compared with the first IOP of the study (18.7±3.3; p=0.029), and the IOP just before the specific test started (18.4±3.0; p=.013). The 60 yo group had a significant decrease in IOP with the alternating accommodation test (19.1±2.4 vs 17.8±2.2; p=.028). When compared to the 20 yo group, the 60 yo group had smaller pupils when accommodating or nonaccommodating, narrower anterior chamber angles (36.4±7.1 vs 47.6±6.0 degrees; p=.001) and shallower anterior chambers (2.94±0.42 vs 3.22±0.24mm; p=0.001).
These results find that “CM exercises” do lower IOP. The effect is not lost with aging. Apparently, as one ages the ciliary muscle continues to contract and relax despite no effect on lens shape (presbyopia). With a modified experimental design, it may be possible to lower IOP more and maintain the effect for longer.
This is a 2020 ARVO Annual Meeting abstract.
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