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

To investigate conjunctival vascular density (VD) using Anterior Segment Optical Coherence Tomography Angiography (OCTA) in Scleral Contact Lens (ScCL) wearers.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.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).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.