In Vivo Evaluation of the Limbus Using Anterior Segment Optical Coherence Tomography.

Purposes: To investigate the limbal structure using anterior segment optical coherence tomography (AS-OCT) and compare the difference between a Chinese Han population and a Caucasian population. Methods: Sixty healthy Chinese Han subjects (109 eyes, Chinese group) and 32 healthy Caucasian subjects (51 eyes, Caucasian group) were included in this comparative cross-sectional study. The central cornea and the superior, inferior, nasal, and temporal limbal regions of each subject underwent Fourier-domain AS-OCT. The following parameters were measured: corneal epithelial thickness (CET), maximum limbal epithelial thickness (LET), the mean LET, the width of limbus, distance between scleral spur and the location where limbal epithelium was the thickest (S-T), and limbal epithelial area between scleral spur and the end of Bowman's layer (LEA). Results: CET was similar in both groups (P = 0.577). The width of limbus was more than 32.8% greater in all limbal quadrants in the Caucasian group (range, 1.25-2.20 mm) than in the Chinese group (range, 0.81-1.40 mm). S-T and LEA were also significantly higher in all limbal quadrants in the Caucasian group (all P < 0.001). The maximum LET and mean LET were 7.8% and 6.9% thicker at the nasal limbus and 8.1% and 8.7% thicker in the temporal limbus in Caucasian subjects than in Chinese subjects. Conclusions: The limbal structures can be visualized using AS-OCT and differ significantly between the Caucasian and Chinese eyes. Translational Relevance: Research of the limbus and surgeons performing procedures involving the limbal area should take into consideration of the anatomic differences especially when limbus is used as an anatomic reference.