Blood flow in vessels supplying the eye in persons with degenerative myopia. Part II. Blood flow in the central retinal artery

Introduction
To analyse the blood flow parameters in the central retinal artery (CRA) of myopic patients depending on the severity of the degenerative changes in ocular fundi.

Material and methods
70 myopic subjects, aged 18 to 79 years, with the axial ocular length ranging between 22.61 and 33.36 mm (27.9 ± 5.37) were examined. According to the extent and severity of degenerative lesion progression, patients were divided into 4 groups: I – no degenerative changes on the fundus (n = 32; K – 23, M – 9), II – myopic crescent (n = 20; K – 14, M – 6), III – retinal thinning accompanying the myopic crescent (n = 8; K – 6, M – 2), IV – extensive chorioretinal atrophy in the fundus (n = 10; K – 7, M – 3). Blood flow parameters in the central retinal artery were determined using Doppler Color ultrasonography (Aplio SSA, Toshiba), with the 12 MHz probe. The following, standard parameters were analysed: maximum (Vmax), minimum (Vmin) and mean (Vm) velocity at systole, resistive index (RI) and pulsation index (PI). The differences were analysed statistically using the variance analysis and the Spearman’s rank correlation coefficient, with the p< 0.05 assumed as statistically significant.

Results
The severity of degenerative retinal changes correlated with the blood flow in CRA. At lowered Vmax, Vmin, Vm acompanying the elevated RI and Pi the lesions progressed rapidly and were considerably more advanced and extensive.

Conclusions
The extent and severity of degenerative processes within the myopic retina are directly proportional to blood flow deterioration in the central retinal artery. This association can explain the development and progression of myopic retinopathy.