Evaluation of Scleral Thickness in Patients With Keratoconus

To evaluate scleral thickness of patients with keratoconus by anterior segment optical coherence tomography (AS-OCT).

Fifty-two eyes of 42 patients with keratoconus (group 1) and 42 right eyes of 42 healthy individuals (group 2) were included. Scleral thickness measurements were taken with AS-OCT 6, 4, and 2 mm behind the scleral spur in four gaze positions: superior, inferior, temporal, and nasal. The data including central corneal thickness (CCT) by Pentacam from patients with keratoconus was also analyzed and its relationship with scleral thickness was evaluated.

In group 1, mean scleral thickness from 6 mm posterior to scleral spur in superior, inferior, temporal, and nasal quadrants were 397±35.3 (320-482), 408±29.5 (341-467), 393±40.8 (297-469), and 403±35.8 (310-482) μm, respectively. In group 2, mean scleral thickness from 6 mm posterior to scleral spur in superior, inferior, temporal, and nasal quadrants were 440±42.2 (346-552), 461±33.9 (390-563), 451±46.6 (340-549) and 448±34.3 (350-521) μm, respectively. The mean scleral thickness in group 1 was significantly lower in all quadrants compared with group 2 ( P <0.001). The mean CCT in group 1 was 478.22±87.55 (306-632) μm. Positive correlation was found between scleral thickness measurements taken at 4 mm (ϱ=0.312, P =0.037) and 2 mm (ϱ=0.308, P =0.039) posterior from the scleral spur in the inferior quadrant and CCT.

Scleral thickness was significantly lower in patients with keratoconus. Scleral thickness and CCT were positively correlated in inferior quadrant. Even though it is not yet known whether scleral changes are progressive or not, scleral thickness measurement may also find a place in the diagnosis and follow-up of patients with keratoconus in the future.