Anterior scleral thickness dimensions by swept-source optical coherence tomography

Clinical relevance: Given the association of scleral characteristics with many ophthalmological diseases, there is an important need to measure the anterior scleral thickness (AST).Background: This study examined the AST by swept-source optical coherence tomography (SS-OCT) in a large healthy population, assessing also the reproducibility of AST measurements and the correlation with different parameters.Methods: Cross-sectional study in 605 eyes of 605 subjects. AST measurements were made in the temporal and nasal quadrants at 1 (AST1) and 3 mm (AST3) from the scleral spur using SS-OCT. These dimensions were then assessed for associations in a multivariate model with the factors age, sex, refractive error, conjunctival-Tenon capsule thickness (CTT), anterior chamber angle (ACA), intraocular pressure (IOP), iris thickness (IT), limbus-sulcus distance (LSD), and ciliary muscle thickness (CMT). The reproducibility of the AST measurements was determined in 30 of the participants.Results: The mean age was 42.6 ± 17.3 years (range 5 to 86 years). The following means were recorded: AST1 was 522.3 ± 65.7 µm (355 to 761) and 558.4 ± 71.5 µm (357 to 889); AST2 was 513.3 ± 67.3 µm (343 to 732) and 574.4 ± 71.6 µm (389 to 789), and AST3 548.8 ± 71.9 µm (356 to 762) and 590.1 ± 76.6 µm (414 to 873) in the temporal and nasal quadrants respectively, being thicker the nasal quadrant (all p < 0.001). A positive correlation was detected between AST and age, sex, temporal ACA and LSD (all p ≤ 0.043), being negative the correlation with CMT (p ≤ 0.044). No correlation was observed between AST measurements and refractive error, CTT and IT (p ≥ 0.064). The reproducibility of AST measurements was excellent (intraclass correlation coefficient ≥0.951).Conclusions: SS-OCT allows for in vivo AST measurements. Our data contained a wide range of measurements, showing an association between AST and age, sex, ACA, LSD and CMT.