Ocular surface characteristics and its association with soft contact lens fitting

To analyse the associations between ocular surface shape parameters and soft contact lens fitting.

A total of 106 eyes of 53 participants (53 right and 53 left eyes) fitted with standard silicone hydrogel soft lenses were analysed retrospectively. The sagittal height of the lenses was obtained from an independent publication. The lens fit was analysed objectively with proprietary software and corneo-scleral parameters were obtained with the Eye Surface Profiler. The relationship between the sagittal height of the eye (OC-SAG) and the lens (CL-SAG) was defined as the delta-sag (δ-sag) and characterised for this group.

The OC-SAG and δ-sag were in the range of 3600 and 400 μm, respectively, with no statistically significant differences between the right and left eyes. There were statistically significant differences between the corneoscleral junction (CSJ) angle of the right and left eyes (p = 0.002). The nasal portion showed the sharpest transition in both eyes and was significantly different between the right and left eyes only in that specific quadrant (p < 0.001). The peripheral cornea (α) was steeper with a mean value around 38°. The proximal sclera (β) showed a flatter slope close to 36° in both eyes. Following the pattern of the CSJ angle, there were statistically significant differences only between the nasal-α of the right and left eyes (p < 0.001). There were no significant correlations between the δ-sag and the lens fitting features in either eye (p > 0.05). Some moderate and strong associations between the lens fit and peripheral ocular parameters were found, although they were not consistent between the right and left eyes.

Soft contact lens movement seems to be influenced by the corneo-scleral transition at the superior and inferior quadrants. It would be better to focus on the slopes in these peripheral areas rather than the central corneal parameters or the sagittal height.