Abstract
Purpose:
To investigate retinal vascular anatomy and function in eyes with pathologic myopia by Dynamic Vessel Analyzer (DVA, Imedos, Jena, Germany) in order to explain why these eyes are resistant to diabetes-related changes.
Methods:
A total of 20 patients with pathological myopia (20 eyes) were included in the study and compared with 20 eyes of age and sex matched healthy control subjects. Complete ophthalmologic examination, dynamic and static retinal vessels analysis were performed on all participants.
Results:
The dynamic analysis of eyes stimulated by flickering light highlighted a mean arterial dilation of 2.44±1.59% in myopic eyes and 3.28±1.76% in healthy eyes (p=0.189). Mean venous dilation was 3.45±1.82% and 4.45±2.72%, respectively (p=0.409). In myopic patients, the static retinal analysis 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 control subjects mean CRAE was 190.3±11.93 and mean CRVE 215.7±13.30 (both p = 0.0031 vs respective measurements in myopia) and mean AVR was 0.88±0.04 (p=0.913). An inverse relationship between axial length and CRAE and CRVE (r2 = 0.18, p=0.0051 and r2 = 0.18, p=0.0165, respectively) was evidenced by the linear regression analysis.
Conclusions:
Static and dynamic vessels analysis showed that myopic eyes have retinal posterior pole vessels with reduced diameter, but with normal function. The vascular network at the posterior pole does not appear to play a key role in determining chronic state of ischemia involved in the relative protection from diabetic retinopathy.