Passant Sayed Saif

To evaluate within-group corneal biomechanical changes induced by LASIK, photorefractive keratectomy (PRK), and corneal cross-linking (CXL) using Corvis ST, while accounting for differences in baseline corneal status between refractive surgery candidates and keratoconic eyes. This prospective comparative study included 150 eyes of 150 patients undergoing LASIK (n = 50), PRK (n = 50), or epithelium-off CXL for keratoconus (n = 50). Corneal biomechanical parameters were assessed preoperatively and at 6 months postoperatively using Corvis ST, including deformation amplitude (DA), stiffness parameter at first applanation (SP-A1), DA ratio at 2 mm, Ambrósio relational thickness horizontal (ARTh), corneal biomechanical index (CBI), and tomographic biomechanical index (TBI), the latter derived from combined Pentacam tomography and Corvis ST measurements. Within-group changes were analyzed using paired parametric or non-parametric tests as appropriate. Between-group comparisons were performed using ANCOVA or linear mixed-effects models adjusted for baseline values, age, central corneal thickness, and biomechanically corrected intraocular pressure. LASIK and PRK eyes demonstrated significant postoperative increases in DA, DA ratio at 2 mm, CBI, and TBI, along with significant reductions in SP-A1 and ARTh (all p < 0.001), indicating biomechanical weakening relative to their preoperative state. The magnitude of weakening was greater following LASIK than PRK after baseline adjustment. In contrast, keratoconic eyes treated with CXL showed significant reductions in DA, DA ratio, CBI, and TBI, and a significant increase in SP-A1 (p < 0.001), consistent with biomechanical stiffening. These changes occurred despite differing baseline biomechanical profiles between groups. LASIK and PRK are associated with measurable corneal biomechanical weakening, whereas CXL induces biomechanical stiffening in keratoconic corneas. These findings should be interpreted within the context of distinct baseline corneal conditions rather than as direct comparisons of procedural efficacy. Corvis ST provides a robust framework for quantifying procedure-specific biomechanical directionality within different clinical settings.

To assess the effect of systemic hypertension on retinal and peripapillary vascular density and visual field (VF) deviation. This prospective observational case-control study included 136 eyes, 68 eyes of 34 patients with hypertension (HTN), and 68 eyes of 34 healthy controls. HTN patients: group 1: ≤5 years HTN duration was less than 5years and group 2: HTN > 5 years. All participants were assessed using OCTA quantitative (vessel density (VD), foveal avascular zone (FAZ) area, superficial capillary plexus (SCP), deep capillary plexus (DCP), choriocapillaris (CC), radial peripapillary capillaries (RPC)) and 24 − 2 glaucoma hemifield tests. The results were recorded and analyzed. Macula OCTA revealed a reduction in foveal and total VD in the SCP and DCP in HTN groups 1 and 2. There was a reduction in the inferior CC layer in the HTN group2, enlarged FAZ area and perimeter were demonstrated with reduced circularity. in DCP in HTN. Humphrey visual field (HFA) testing in HTN group 1 and 2. revealed that visual field defects occurred more often in group 2 patients with longer HTN duration than in group 1 and controls. The association between the duration of systemic hypertension and the diminution in vessel density, VF deviation, and defects justifies the verification of longitudinal studies. OCTA and visual field examinations are tools for monitoring systemic hypertension.

To evaluate endothelial cell density (ECD) and corneal biomechanical changes following implantation of Veriflex and Implantable Collamer Lens (ICL) phakic intraocular lenses (pIOLs) over a 12-month period. Sixty patients (117 eyes) were included in this prospective comparative study. 58 eyes underwent implantation with the Veriflex lens (Group I), while 59 eyes received the ICL (Group II). Preoperative and postoperative ECD and corneal biomechanical values were assessed using specular microscopy and Corvis St at baseline, 6 months, and 1 year. Endothelial cell loss percentages and corneal biomechanical changes were calculated and compared between the 2 groups. Preoperatively, the mean ECD was 2683.4 ± 340.6 cells/mm ² in Group I and 2732 ± 322.8 cells/mm ² in Group II ( P  = 0.718). At 1 year, Group I exhibited a significantly greater reduction in ECD compared to Group II (P = 0.021), indicating higher endothelial cell loss with Veriflex. The mean endothelial cell loss at 12 months was 5.4% (145.7 ± 62.8 cells/mm ² ) in Group I compared to 1.53% (42 ± 17.3 cells/mm ² ) in Group II ( P  < 0.001). The Veriflex group showed greater corneal biomechanical changes, with a deformation amplitude (DA) increase to 1.15 ± 0.11 mm and a highest concavity time (HCT) of 17.2 ± 1.1 ms, while the ICL group demonstrated more stable biomechanics, with a DA of 1.09 ± 0.09 mm and an HCT of 16.6 ± 1.0 ms at one year postoperatively. Both Veriflex and ICL pIOLs resulted in a decrease in ECD over one year, with Veriflex showing a significantly higher rate of endothelial cell loss. These findings suggest that ICL may be a safer option for long-term endothelial preservation. Long-term studies are required to assess the continued impact of both lenses on corneal endothelial health.

Purpose: To describe retinochoroidal vascular alterations in patients treated through Egypt’s National Treatment program for hepatitis C using en face optical coherence tomography angiography (OCTA). Patients and methods: This cross–sectional study included 60 patients (120 eyes) with a history of hepatitis C virus (HCV) infection, aged 34–61 years, who had achieved sustained virologic response after treatment with direct-acting antivirals. Exclusion criteria included ocular diseases, diabetes, or systemic conditions affecting microvasculature. Retinal and choroidal vascular parameters were assessed using OCTA, including superficial vessel density (SVD), deep vessel density (DVD), foveal avascular zone area, and subfoveal choroidal thickness. Data were analyzed by age subgroup and compared with previous studies. Results: Patients demonstrated a significant reduction in retinal SVD and DVD, particularly in parafoveal areas, and a larger foveal avascular zone compared with normative data (P<0.05). Subfoveal choroidal thickness was notably thinner, correlating with age and treatment duration. Age subgroup analysis revealed greater vascular alterations in older patients (≥50 years), with reductions in parafoveal SVD and DVD being most pronounced. Comparative studies indicate similar trends in microvascular alterations in treated HCV populations, though variations exist due to demographic and methodological differences. Conclusion: En face OCTA reveals significant retinochoroidal vascular changes in post-HCV treatment patients, with age-related exacerbation. These findings suggest that microvascular remodeling persists despite viral eradication, emphasizing the need for long-term ocular monitoring. Further studies are warranted to explore underlying mechanisms and potential clinical implications.