Characterization of Soft Contact Lens Fitting Using Ultra-Long Scan Depth Optical Coherence Tomography

Abstract

Objectives: To evaluate the centration and movement of soft contact lenses and to verify the repeatability of two repeated measurements of the lens centration and movement using ultra-long scan depth optical coherence tomography (UL-OCT).

Methods: A 1-day Acuvue® Define™ lens was tested on both eyes of 10 subjects (5 males and 5 females; mean age, 31.6 years). The centration and blink-induced movement of the contact lens were measured using UL-OCT at 5 min and 30 min after insertion. The measurements were repeated once at each checkpoint.

Results: Good repeatability was found in the lens centration and movement between the two repeated measurements at either checkpoint. The values of the lens movement were 0.457 ± 0.248 mm and 0.402 ± 0.229 mm at 5 min and decreased to 0.197 ± 0.065 mm and 0.211 ± 0.110 mm at 30 min after insertion for the right and left eyes, respectively (P < 0.05).

Conclusions: The custom-built UL-OCT presented good repeatability of centration and movement in Define lenses at 5 min and 30 min after insertion. Most of the lenses were centered temporal and inferior to the cornea during the first 30 min wearing period. Compared with 5 min after insertion, the lens was centered better and exhibited less movement at 30 min.

Figure 1

Evaluation of the Define lens centration using UL-OCT images. (a) Horizontal meridian. (b) Vertical meridian. The nasal (blue dot)/temporal (green dot)/inferior (blue dot)/superior (green dot) boundaries of the inner painted pupil/iris in lenses were indicated. The perpendicular distances between those four points and the corneal apex (red dashed lines) were marked as “A,” “B,” “C,” and “D.” The difference between “A” and “B” was defined as the decentration at the horizontal meridian (a). The difference between “C” and “D” was defined as the decentration at the vertical meridian (b). The bars indicate 500 μm.

Figure 2

Assessment of the Define lens movement through UL-OCT images. (a) was before a blink and (b) after. The lens movement was tracked as the perpendicular distance between red/green dots and the yellow dashed line. The linear distance “D” was defined as the amount of the lens movement. The bars indicate 500 μm.

Figure 3

Bland-Altman plots of the differences between two measurements of the lens centration and movement at 5 min after insertion. The mean differences of the variables between two repeated measurements for lens centration (a)–(d) at both meridians and the blink induced (e)-(f). The mean differences in the values between the two measurements were around approximately zero, and the 95% confidence limits were represented by the dotted lines. OD: the right eye; OS: the left eye.

Figure 4

Bland-Altman plots of the differences between two measurements of the lens centration and movement at 30 min after insertion. The mean differences of the variables between two repeated measurements for lens centration (a)–(d) at both meridians and the blink induced (e)-(f). The mean differences in the values between the two measurements were around zero. OD: the right eye; OS: the left eye.

Figure 5

Scatter plots of the lens centration at 5 and 30 min. The lenses were centered temporal and inferior to the corneal apex during the first 30 minutes. Better centration and less movement occurred at 30 min. For the right eye, positive values were denoted with “N” (nasal) and “I” (inferior), and negative with “T” (temporal) and “S” (superior). The horizontal variables of the lens centration were opposite for the left eyes. OD: the right eye; OS: the left eye.