The effect of corneal dryness on optical coherence tomography angiography

Dry eye disease is an important clinical condition that directly affects imaging techniques due to tear film instability and disruption of ocular surface integrity. Optical coherence tomography angiography (OCTA) is highly sensitive to tear film breakup and surface irregularities; therefore, both image quality and the reliability of microvascular measurements may decrease in the presence of dry eye. Accordingly, this study aimed to compare pre-instillation (Pre-D) and post-instillation (Post-D) OCTA quality scores, acquisition time, and vascular density measurements between dry eye and normal eyes. The findings demonstrated that Pre-D OCTA quality scores were significantly lower in the dry eye group (38.17±2.72 vs. 39.67±1.30; p=0.001), and acquisition time was significantly longer (61.13±14.84 s vs. 49.20±11.98 s; p=0.001). Following artificial tear instillation, an increase in quality scores and a marked decrease in acquisition time were observed, with these improvements being more pronounced in the dry eye group (quality increase: 3.9% vs. 1.8%). Although intergroup differences in microvascular parameters were mostly limited, inferior parafoveal superficial vascular complex vessel area density (SVC VAD) showed a significant increase after instillation in the dry eye group (p=0.019). In conclusion, tear film instability has a clear impact on OCTA image quality, and artificial tear application significantly enhances technical quality, particularly in individuals with dry eye. The results also indicate that the effects of clinical parameters on OCTA variables are multifactorial. These findings highlight the importance of considering tear film integrity when interpreting OCTA measurements and suggest that incorporating artificial tear instillation into clinical practice may improve imaging reliability. KEYWORDS: Dry eye disease , Tear film instability, Optical Coherence Tomography Angiography, Microvascular imaging