Precision of limbal ischemia evaluation in ocular chemical injuries with anterior segment optical coherence tomography angiography

Purpose To evaluate the limbal ischemia objectively in ocular surface chemical injuries by using anterior segment optical coherence tomography angiography (AS-OCTA). Methods In this cross-sectional study, acute ocular surface chemical injury patients with less than 1 week injury history were enrolled. Demographic data of the patients were noted, and detailed ophthalmological examination with Dua classification was performed. AS photographs and AS-OCTA images were obtained and used for the assessment of limbal ischemia. To visualize the limbal vasculature, the device was focused manually to get a sharp image for all 4 quadrants of the limbus. The absence of vasculature was regarded as "ischemia," and the amount of the ischemia was defined in clock hours. The limbal ischemia detected in clinical evaluation with biomicroscopy was compared with the AS-OCTA detected ischemia amount to make a conclusion for the correlation. Results Nineteen eyes of 18 patients with acute ocular surface chemical injury were enrolled to the study (2 female, 16 male). The mean age was 35.1 +/- 10 (18-55), and the mean best corrected visual acuity was 0.75 +/- 1 (0.1-3.1) LogMAR. The causative agents were acid in 6 and alkaline in 12 patients. Limbal ischemia detected by using AS-OCTA was greater ((5.8 +/- 2.6 (2-10) clock hours) than that detected in biomicroscopy (4.8 +/- 2.4 (2-12) clock hours). The difference was statistically significant (p < 0.0005). Conclusion AS-OCTA has a significant importance on limbal vascularity visualization; therefore, its use for more objective and sensitive evaluation of limbal ischemia in ocular surface chemical injuries seems to have a crucial impact. AS-OCTA images may reveal the extension of limbal ischemia more precisely than clinical evaluation with biomicroscopy. However, future studies with higher number of patients are needed to come to a specific conclusion.