Static characteristics and dynamic functionality of retinal vessels in longer eyes with or without pathologic myopia.

Purpose: To analyze major retinal vessels in eyes with high myopia by means of the Dynamic Vessel Analyzer (DVA) in order to gather insight on retinal vascular functionality and better understand why these eyes are resistant to diabetes-related changes.
Methods: A total of 20 high-myopia eyes with pathologic myopia, 20 high-myopia eyes without pathologic myopia and 20 age- and sex-matched control subjects (without pathologic myopia) were included and compared.
Results: Dynamic analysis showed mean arterial dilation of 2.44 ± 1.59 % in high-myopia eyes with pathologic myopia, 2.67 ± 1.17 in high-myopia without pathologic myopia eyes, and 3.28 ± 1.46 % in healthy eyes. Mean venous dilation was 3.45 ± 1.82 %, 3.57 ± 1.72, and 4.45 ± 2.72 % respectively. Static analysis in high myopia eyes with pathologic myopia showed a mean central retinal artery equivalent (CRAE) of 171.6 ± 24.3, a mean central retinal vein equivalent (CRVE) of 199.5 ± 27.73, and a mean arteriovenous ratio (AVR) of 0.86 ± 0.01. In patients with high myopia without pathologic myopia, we found a mean CRAE of 173 ± 21.6, a mean CRVE of 198.2 ± 18.8, and a mean AVR of 0.87 ± 0.1. In control subjects, mean CRAE was 190.3 ± 11.93, mean was CRVE 215.7 ± 13.30, and mean AVR was 0.88 ± 0.04.
Conclusions: Static and dynamic tests revealed that in high-myopia eyes, the vessels at the retinal posterior pole have reduced diameter, but are functionally comparable to control subjects. This supports the hypothesis of reduced oxygen consumption in high-myopia eyes.