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Abhiram S. Vilupuru, Susan Tsai, Alexandra Almazan, Susan S. Lee, Michael R. Robinson, James A. Burke; Comparative Anatomy of Angle Biometrics with Anterior Chamber OCT. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6279.
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© ARVO (1962-2015); The Authors (2016-present)
To accommodate aqueous bypass shunt devices and anterior chamber flow tubes from glaucoma drainage valves, a clear understanding of the iridocorneal angle anatomy is required to avoid toxicity to the iris and cornea. In addition, proper species selection is critical during the development of angle devices to translate information from animal to man. We performed anterior chamber optical coherence tomography (AS-OCT) on several commonly used species in preclinical development to compare the angle biometrics with published information in man.
Six species were evaluated: cats, beagle dogs, minipigs, owl monkeys, cynomolgus monkeys, and rhesus monkeys, N= 6 or 7 per species. Iridocorneal angle measurements were performed using the Visante® AS- OCT, Horizontal AC single scan protocol. The parameters evaluated were AC angle (degrees), angle opening distance (AOD) defined as the distance (mm) along a line perpendicular to Schwalbe’s line to the iris and the angle recess area (ARA) defined as the triangular area (mm2) formed by the AOD, the iris surface, and the inner corneoscleral wall (sides of the triangle). The species measurements were compared with published OCT biometrics in human1 using comparable parameters, AOD 500 and ARA 500.
AC angle was largest in the cat 63 ± 6 > owl monkey 54 ± 4 > dog 42 ± 4 > minipig 40 ± 3 > rhesus monkey 36 ± 1 > cynomolgus monkey 34 ± 2 degrees. AOD was cat 3.3 ± 0.5 > owl monkey 2.05 ± 0.2 > dog 1.08 ± 0.1 > rhesus monkey 0.92 ± 0.06 > minipig 0.64 ± 0.04 > cynomolgus monkey 0.43 ± 0.03 mm. ARA was cat 3.5 ± 0.1 > owl monkey 1.41 ± 0.2 > dog 0.88 ± 0.1 > rhesus monkey 0.62 ± 0.06 > minipig 0.21 ± 0.05 > cynomolgus monkey 0.15 ± 0.01 mm2.
The cynomolgus monkey, a commonly used species in preclinical glaucoma studies, has the smallest and narrowest angle of all the species evaluated. The cat, owl monkey, dog and rhesus monkey have both AOD and ARA measurements within 10% or greater to the published OCT biometrics in man (mean AOD 0.68 mm, mean ARA 0.69 mm2), with dog and rhesus monkey having the closest measurements to man and are relevant species to evaluate angle devices.
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