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Tobin Ansel, Ann Nour, Alexandra Benavente-Perez; Non-invasive Measurements of Ocular Perfusion Pressure in Marmosets and its Relationship with Myopia Development and Progression. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5513.
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To develop a non-invasive protocol to measure ocular perfusion pressure (OPP) in marmosets, and to describe how OPP changes with age and with myopia development and progression.
OPP was measured non-invasively in a total of 29 marmosets (N=12 for repeatability and reproducibility; N=11 treated; N=6 age-matched untreated). The eleven treated marmosets wore -5D contact lenses for 10 weeks from the age of 67.64±7.26 days (N=5 binocular treatment; N=6 OD -5D/ OS plano). Refractive error (Rx), vitreous chamber depth (VC), and OPP measurements were recorded immediately prior to treatment, and at 4, 8 and 10 weeks during treatment (T4, T8, T10). OPP calculations were derived from non-invasive intraocular pressure (IOP; Tonopen AVIA Vet) and blood pressure measurements (BP; CODA monitor system) performed under anesthesia (alfaxan, 0.0015 cc/g, im). OPP was calculated as two thirds of mean arterial pressure (MAP) minus IOP.
Treatment with -5D contact lenses induced compensatory changes in refraction (change in Rx at the end of treatment: monocular group: -3.65±1.54D; binocular group: -5.57±1.34D) and VC (change in VC: monocular group 645.38±116.59 µm; binocular group: 819.07±124.48 µm). OPP measurements were normally distributed, repeatable and reproducible (IOP: CoR: 9.82%, CoV: 18.23%, CoRepro: 14.49%; MAP: CoR: 2.08%, CoV: 2.35%, CoRepro: 15.38%). OPP remained within 2.73±7.56 mmHg in untreated marmosets as they aged (repeated ANOVA, p>0.05). However, both treatment groups showed a significant increase in OPP as myopia developed (change in OPP at the end of treatment: monocular group: 1.48±6.38mmHg, p=0.015; binocular group: 9.35±5.55 mmHg, p=0.013).
Non-invasive measurement of ocular perfusion pressure in anesthetized marmosets is a safe and repeatable procedure. OPP did not change significantly with age within the first year of life, but increased with myopia development and progression. This relationship between ocular perfusion pressure and myopia may be related to changes in metabolic demands with increased axial length, and suggests an active vascular autoregulatory mechanism in marmoset eyes.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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