Visser Esther-Simone, Visser Rients, Van Lier Henk J J
Visser Contact Lens Practice and the University of Nijmegen, Nijmegen, The Netherlands.
Optom Vis Sci. 2006 Apr;83(4):233-6. doi: 10.1097/01.opx.0000214297.38421.15.
The purpose of this study was to investigate whether back surface toric scleral lenses stabilized (i.e., returned to their original position after rotation) and how long the return times were. Return time was studied in relation with actual wearing time and comfort; moreover, the performance of the spherical scleral lens was compared with the toric scleral lens design.
Toric scleral lenses were rotated clockwise and counterclockwise over 60 degrees. Return times and the actual wearing time were recorded. Results were transformed into nasal and temporal return times for symmetry reasons. The present and former types of correction were compared for comfort (ranging from 0: very poor to 10: excellent) and regular wearing time. All the subjects attended regular follow-up visits.
Forty-three subjects (43 lenses) entered the study. All the lenses returned to the original position within a median of 4 seconds after nasal rotation and 6 seconds after temporal rotation. A significant correlation was found between mean return times and actual wearing time (r = 0.63). Significant increases in median comfort (from 6-8) and median wearing time (from 15-16 hours) were demonstrated when the toric scleral lens designs were compared with the former type of correction (both p < 0.001). Median comfort and median wearing time also increased significantly after changing from spherical scleral lenses to the toric design (from 7-8 and from 14-16 hours, both p < 0.001, n = 27 eyes).
Toric scleral lenses returned rapidly to their original position after rotation. The flattest meridian of the toric scleral lenses stabilized symmetrically. Patient interviews demonstrated differences in comfort and wearing time in favor of the toric design.
