Abstract
Purpose :
Multifocal contact lenses (MCLs) are designed to provide near vision functionality in presbyopia. They rely on proper deployment of the multifocal power profile on the cornea and on optical interactions between the MCL and eye. Using custom-developed spectral Anterior Segment Optical Coherence Tomography (OCT) we evaluated the contact lens profile on eye, and potential conformity to the cornea.
Methods :
OCT images were obtained on one eye of 13 subjects (age: 35.69 ± 13.83 y/o; Spherical error from -4.75D to +2.50D), with naked eyes and with MCLs on eye. All eyes were tested (5 repetitions) with the same MCLs: 1-Day Acuvue® Moist Brand MCL (Johnson & Johnson® Vision Care; -2.00D distance power; 8.4mm base curve; 14.3mm diameter) and three different additions: +1.25D (Low, L), +1.75D (Mid, M) and +2.50D (High, H). The OCT acquisition speed was 25000 A-Scans/s, the axial range was 7mm in depth, and the axial pixel size 3.4μm. Images were processed using custom routines for segmentation, fan distortion correction, 3D model construction, and surface fitting. The radius of curvature of the external surface of the MCLs (RCL) and the anterior surface of the naked cornea (RC) were obtained from spherical fitting within a 3-mm diameter central area (addition area) and within a 3-6 mm peripheral ring.
Results :
RC ranged from 7.5 to 8.2 mm across subjects (8.02±0.22mm, on average). The shift in RCL in the periphery (by 0.55 mm on average) was consistent with the flattening produced by the negative MCL base power, and was constant independently of the corneal power of the subject. RC and RCL were correlated (p<<0.005) in the periphery for the three MCL additions (r=0.87, 0.84 and 0.82 for L, M and H adds, respectively) and also in the addition area (p<<0.005, r=0.85, 0.82, 0.78, L, M, H, respectively). The average RCL across subjects in the addition area was 8.37±0.31mm (L), 8.32±0.34mm (M) and 8.30±0.28 mm (H), and in the periphery was 8.59±0.30mm (L), 8.54±0.33mm (M) and 8.53±0.28mm (H), consistent with a relative central steepening, particularly for the higher add.
Conclusions :
OCT provided with quantification tools allows to study the fitting of MCLs on eye in vivo. We found that, overall, soft MCLs conform to the underlying cornea, both in the central addition area and the periphery. However, the near central add is provided, as expected.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.