Optical coherence tomography angiography in herpetic leucoma.

BACKGROUND: Herpes simplex virus (HSV) keratitis remains a leading infectious cause of blindness worldwide. Although all forms of HSV keratitis are commonly recurrent, the risk is greatest in stromal keratitis, which is the most likely to result in corneal scarring, thinning, and neovascularization. Recent studies showed the ability of Optical Coherence Tomography Angiography (OCTA) to detect and study vascular abnormalities in the anterior segment, including abnormal corneal vessels. This study intends to investigate the potential of OCTA device to image and describe quantitatively the vascularization in eyes diagnosed with herpetic leucoma and to discuss and review the usefulness of this technique in this pathology. METHODS: A Cross-sectional study was made, including 17 eyes of 15 patients with leucoma secondary to herpetic keratitis. All eyes underwent anterior segment Slit-Lamp photography (SLP), and OCTA with en-face, b-scans and c-scans imaging. The vessel density (VD) was analyzed in the inferior, nasal and temporal corneal margin in all patients, and in the central area, in eyes with central corneal neovascularization (CoNV). The measurements were calculated after binarization with ImageJ software, using OCTA scans with 6 × 6 mm in a depth of 800 µm. RESULTS: Patients included had a mean age 53.267 ± 21.542 (years ± SD). The mean total vessel area was 50.907% ± 3.435%. VD was higher in the nasal quadrant (51.156% ± 4.276%) but there were no significant differences between the three analyzed areas (p = 0.940). OCTA was able to identify abnormal vessels when SLP apparently showed no abnormal vessels; OCTA was able to distinguish between larger and smaller vessels even in central cornea; OCTA scans allowed the investigation of several corneal planes and the relation of them with clinical findings. CONCLUSIONS: OCTA can be useful in both qualitative and quantitative follow-up of patients and may become a non-invasive alternative to objectively monitor treatment response in eyes with corneal vascularization due to herpetic infection.

ANALYSIS OF CONJUNCTIVAL VASCULAR DENSITY IN SCLERAL CONTACT LENS WEARERS USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PURPOSE: To investigate conjunctival vascular density (VD) using Anterior Segment Optical Coherence Tomography Angiography (OCTA) in Scleral Contact Lens (ScCL) wearers. METHODS: In this cross-sectional study, the conjunctival blood VD was assessed using OCTA with an anterior segment lens adapter. The nasal surface of each eye (6 ×6 mm) was scanned to a depth of 800 µm with ScCL and fifteen minutes after removing the lens. Conjunctival VD was defined as the percentage of the scanned volume occupied by vessels in which blood flow was measured. Measures of limbal indentation were subjectively determined by two independent observers using Anterior Segment Optical Coherence Tomography (AS-OCT). Comparisons between VD measurements before and after ScCL removal and correlations between conjunctival VD, time of use, vault and indentation values were also investigated. RESULTS: A total of 23 patients (3 females, 20 males) with keratoconus, with a mean age (years±SD) of 38.74±10.38 were included in the study. VD was significantly higher without ScCL (71.75%±2.97) than VD measured with ScCL (69.81%±2.63), p=0.02. A moderately negative correlation was found between indentation and vault (r=-0.44, p<0.05) and a positive tendency regarding the time of wearing ScCL and indentation (r=0.11 and r=0.068, respectively). CONCLUSIONS: Using OCTA with an anterior segment lens adapter, the ocular surface blood VD was imaged and assessed with good repeatability and reliability. This study presents a new possible application of OCTA to investigate and monitor conjunctival vasculature in ScCL wearers. This results cautiously suggest that the repeated use of ScCL can cause vascular alterations in conjunctiva of the eyes of ScCL wearers, possibly due to a hidden hypoxia caused by prolonged limbal indentation.