Purpose: To evaluate eyelid and eye contour factors that can influence the fitting of toric soft contact lenses (TSCLs).
Methods: Thirty-two subjects (64 eyes) were enrolled and fitted with Lo-Torque design TSCLs. One eye of each subject was randomly selected. High-resolution digital images were acquired after the subjects had worn the lens for 20 minutes, and the images were then processed with Adobe Photoshop. The palpebral aperture (PA), various angles of the eyelid, horizontal visible iris diameter (HVID), and lens parameters were obtained. Finally, lens fitting was evaluated.
Results: During the assessment of the correlations between the eyelid and eye contour factors and the lens fitting, there were four pairs of significant correlations: (1) the PA and rotational direction of the lens: larger eye PA was associated with a greater possibility of nasal rotation of the corresponding lens (P=0.03); (2) the angle of the central lower lid (θ3) and the rotational stability of the lens: the larger the angle was, the worse the rotational stability was (P=0.02); (3) the lower lid angle of the medial canthus (θ5) and temporal rotational recovery: the smaller the angle was, the more quickly the lens recovered (P=0.05); and (4) HVID and routine fitting assessments: the larger the HVID was, the looser the lens fitting (P=0.00). Finally, when assessing correlations between some lens parameters and the orientation of the lens, we found that lower sphere values were associated with quicker lens recovery (P=0.04).
Conclusion: Several eye factors, as well as lens characteristics, had impacts on the TSCLs fitting, including the PA, the angle of the central lower lid (θ3), the lower lid angle of the medial canthus (θ5), and the sphere of the lens. These factors should receive particular attention when fitting TSCLs.