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Alan J Lang, Adam J Roy, Keith Holliday, Tonya Porter, Maggie Young; Range of Vision With Near Center Hydrogel Corneal Inlay in Presbyopic Subjects. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1546.
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© ARVO (1962-2015); The Authors (2016-present)
To understand why presbyopic patients with a broad range of pre-operative refractions can be treated using a single, near-center, design of intracorneal inlay (Raindrop® Near Vision Inlay*, ReVision Optics, Lake Forest, CA, USA).
142 presbyopic subjects with near add requirement (NAR) between 1.50 and +2.50 D with manifest refraction spherical equivalent (MRSE) between -0.50 D and +1.75 D were implanted with a 2 mm diameter hydrogel corneal inlay in the non-dominant eye, under IRB-approved protocols. Uncorrected visual acuity (UVA) for distance, intermediate and near were tested using the Optec 6500 6 months after surgery. Total-eye wavefront differences were used to estimate the anterior corneal surface change and these were used as inputs to a finite eye model for ray-trace analysis. Zemax simulations of letter charts were used to investigate the contribution of adjacent annular power zones within the pupil in order to explain the clinical range of vision.
The average uncorrected distance visual acuity (UDVA) of treated eyes exceeds 0.2 logMAR over the full preop MRSE range investigated, reaching 0.1 logMAR above +1 D. Residual accommodation (2.5 D - Add) does not account for the relatively high UDVA. Zemax letter chart analysis of the contribution of 8 concentric annular zones within a 5 mm pupil reveals that the relatively weak slope of the induced axial power profile (-1 D at 3 mm pupil diameter to 0 D @ 4.5 mm diameter) has little effect on UDVA. For a 4 mm diameter pupil, this distance zone comprises more than 50% of the pupil area. There is a weak correlation between UDVA and postop MRSE (r2 = 0.40), which is, as expected, an approximately linear function of the preop MRSE. Average intermediate UVA remains approximately 0.1 logMAR across the whole MRSE range investigated. Zemax simulations suggest a similar rationale, when applied to the more central pupil zones though the most peripheral region does reduce contrast. Near vision has been discussed previously (ARVO 2013).
The smooth gradient power profile centered on the pupil provides a continuous range of functional vision, minimizing the power profile’s slope within the pupil, which reduces interference with image quality from adjacent annular zones in the pupil. *CAUTION: Investigational device. Limited by Federal (United States) law to investigational use.
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