Variation of vortex veins at the horizontal watershed in normal eyes

PURPOSE

To assess the vascular pattern of choroidal vortex veins at the horizontal watershed zone in normal eyes using optical coherence tomography (OCT).

METHODS

We retrospectively studied 207 normal eyes of 207 patients whose fellow eyes were diagnosed with unilateral retinal diseases without choroidal involvement. Venous anastomosis between the superior and inferior vortex veins and deviation of the horizontal watershed zone were evaluated using 12 × 12-mm en face OCT images. Central choroidal thickness (CCT) was measured on B-mode OCT images.

RESULTS

Vortex vein anastomosis was observed in 92 eyes (44.4%) at the horizontal watershed zone. Superior or inferior deviation of the horizontal watershed was ascertained in 69 eyes (33.3%). The frequency of the anastomosis and deviation did not differ significantly between age groups (P = 0.56 and 0.96, respectively). Mean CCT of all eyes was 221 ± 80 μm. CCT was significantly greater in eyes with anastomosis than in those without (233 ± 73 μm vs 210 ± 83 μm, P < 0.05). However, CCT did not differ significantly between eyes with and without deviation of the horizontal watershed zone (223 ± 74 μm vs 219 ± 82 μm).

CONCLUSIONS

Venous anastomosis at the horizontal watershed zone as well as superior or inferior deviation of the zone were frequently observed in normal eyes. CCT was greater in eyes with than in those without anastomosis, suggesting subclinical vortex vein congestion.

The quantitative measurements of foveal avascular zone using optical coherence tomography angiography in normal volunteers

Purpose

To provide normative data of foveal avascular zone (FAZ) and thickness.

Methods

In this cross-sectional study both eyes of each normal subject were scanned with optical coherence tomography angiography (OCTA) for foveal superficial and deep avascular zone (FAZ) and central foveal thickness (CFT) and parafoveal thickness (PFT).

Results

Out of a total of 224 eyes of 112 volunteers with a mean age of 37.03 (12–67) years, the mean superficial FAZ area was 0.27 mm², and deep FAZ area was 0.35 mm² (P < 0.001), with no difference between both eyes. Females had a larger superficial (0.32 ± 0.11 mm² versus 0.23 ± 0.09 mm²) and deep FAZ (0.40 ± 0.14 mm² versus 0.31 ± 0.10 mm²) (P < 0.001) than males. By multivariate linear regression analysis, in normal eyes, superficial FAZ area varied significantly with the gender, CFT, and deep FAZ. Deep FAZ varied with the gender and CFT.

Conclusion

The gender and CFT influence the size of normal superficial and deep FAZ of capillary network.