Abstract
Purpose:
Explain with clinical data and ray-trace simulations how an intracorneal inlay provides a functional near range, independent of age (Add) and improves intermediate VA.
Methods:
192 emmetropes / low-hyperopes (MRSE: -0.50 to +1.75 D), presbyopic (Add 1.50 to +2.50 D), subjects were implanted with a 2 mm diameter hydrogel corneal inlay (RaindropTM Near Vision Inlay, ReVision Optics)*, in the non-dominant eye. The Optec® 6500 recorded visual acuities. Everyday task performance (five tasks each distance) was ascertained via self-questionnaire. The studies were each conducted according to an IRB-approved protocol. Zemax simulated letter charts yielded near range for fixed VA levels, as a function of pupil size and spectacle defocus, using the inlay effect derived from post-pre wavefront difference maps in a finite eye model. The inlay effect ranged from -4 D at pupil center, returning to the unaltered anterior cornea at 4 mm diameter.
Results:
The mean preop uncorrected near visual acuity (UCNVA) is logMAR 0.51 and by 3 months mean UCNVA is logMAR 0.06 (p<0.001). Near task performance improves (mean increase > 6 points: p<0.001), as does near satisfaction (mean improvement > 2 levels: p<0.001). A series of multivariate statistical models demonstrates postop UCNVA and near (task & satisfaction) are independent of the preop reading add (p ≥ 0.58), postop spherical equivalent (p ≥ 0.27), and patient age (p ≥ 0.45). The mean preop uncorrected intermediate visual acuity is logMAR 0.38 and by 3 months is logMAR 0.12 (p<0.001). In bright light (3 mm), Zemax simulations yield a near 20/20 range between -4.25 D and -2.5 D, an intermediate range -1.25 D to -0.75 D, and at 20/32, a continuous range between -5.0 D (near) and -0.75 D (intermediate); in mesopic conditions (5 mm pupil), a near 20/32 range between -4.0 D and -2.25 D, 20/20 intermediate between -1.0 D and -0.5 D, and a continuous 20/40 from -4.25 D to -0.25 D. The near power > -2.5 D allows closer object distances (e.g., magnification), facilitating near tasks in dim light.
Conclusions:
For emmetropes and low hyperopes, a range of near power ≥ 2.5 D improves near task performance and VA, regardless of age (Add), with high patient satisfaction. The small myopic shift of distance Rx potentially improves intermediate VA. *CAUTION: Investigational device. Limited by Federal (United States) law to investigational use.
Keywords: 479 cornea: clinical science •
678 refractive surgery •
653 presbyopia