Retinal and choroidal microvasculature in early and three months post COVID-19: A case-control study.

To compare the retinal vascular density (VD), choroidal vascularity index (CVI), and choroidal thickness (CHT) between patients infected with COVID-19 and healthy subjects using non-invasive optical coherence tomography angiography (OCTA) and enhanced depth imaging OCT (EDI-OCT) technique. This case-control study was carried out on patients with COVID-19 and healthy controls. Patients' data were acquired immediately after active infection and three months later. The diagnosis was based on clinical symptoms and a positive PCR test. VDs in superficial and deep capillary plexuses (SCP and DCP) and CHT and CVI were measured and compared between groups. A total of 160 eyes from 80 patients (55% female, mean age 51 ± 13 years) and 80 controls (55% female, mean age 49 ± 12 years) were enrolled. In acute phase infection, the mean foveal avascular zone (FAZ) area was 0.28 ± 0.06 mm2 and 0.22 ± 0.05 mm2 in patient and control groups, respectively (P < 0.001). CVI was 61.06 ± 2.59 µm and 72.28 ± 3.84 µm in patients and control groups, respectively (P < 0.001). After three months, the mean FAZ area was 0.28 ± 0.06 mm2 and 0.23 ± 0.05 mm2 in the patient and control groups, respectively (P < 0.001). CVI was 60.93 ± 2.11 µm and 72.46 ± 3.80 µm in patients and control groups, respectively (P < 0.001). Subfoveal CHT was not significantly different between groups (P = 0.69). SCP and DCP VDs were significantly less in the patients' group (P < 0.001). In the patients' group, the VDs in the DCP of the whole images and parafoveal DCP (P < 0.001) were reduced significantly after three months in comparison to the acute phase, while the FAZ area, subfoveal CHT, and CVI were not significantly different. COVID-19 infection may be associated with acute and long-term changes of VDs in the retinal and choroidal vasculature without significant effect on the subfoveal CHT.

A Comparison between Wavefront-Optimized and Wavefront-Guided Photorefractive Keratectomy in Patients with Moderate-to-High Astigmatism: A Randomized Clinical Trial.

Purpose: To compare clinical outcomes of wavefront-optimized (WFO) and wavefront-guided (WFG) photorefractive keratectomy (PRK) in patients with moderate-to-high astigmatism. Methods: Patients with corneal cylinder above 2 diopters and myopic spherical equivalent were randomized into WFO or WFG PRK. Visual acuity (VA), refraction, contrast sensitivity, higher-order aberrations (HOAs), and astigmatic vector differences were documented and compared for 6 months after surgery. Results: The total number of 362 eyes from 181 patients was analyzed. The amount of total aberration was reduced 2.7 root mean square (RMS) and 2.9 RMS in the WFO and WFG groups, respectively (P < 0.001 in each group and between the groups). HOAs including coma, trefoil, and spherical aberrations increased in both the groups (P < 0.001) but were significantly more in the WFO group (P < 0.001). The increased spherical aberration was similar in both the groups (P = 0.12). Surgically induced astigmatism was not significantly different between the groups (P = 0.20). The magnitude of error was significantly higher in the WFO group (P < 0.001), but the absolute angle of error and the arithmetic angle of error were not significantly different between the groups (P = 0.20 and P = 0.30, respectively). Conclusion: WFO and WFG platforms of PRK appear comparable in terms of VA, refractive correction, and total aberration. Yet, HOAs may increase especially after WFO PRK.