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Enhanced accommodation and expanded depth-of-focus in presbyopic scleral implant patients: objective correlates for improved near visual acuity

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Session Details

Session Title: Presbyopic Corrections

Session Date/Time: Monday 15/09/2014 | 16:30-18:30

Paper Time: 18:08

Venue: Boulevard F (Level 1)

First Author: : L.Baitch USA

Co Author(s): :    D. Schanzlin   D. Iskander           

Abstract Details


To establish objective optical correlates to long-term post-operative near visual acuity improvements, which have been observed in Refocus scleral implant surgery patients.


Clinical practice/ Clinical research trial


COAS® Dynamic Stimulus Wavefront Aberrometry was performed pre-operatively, and at three-month intervals over an 18-month post-operative period, on nine presbyopic study patients (MRSE -0.75D to +1.00D, Astig ≤1.00D) ages 50-60 years. Subjects viewed an accommodative target through a dichoptic periscope. Optical wavefronts were recorded sequentially at 7.5 FPS in a 10-second time-series as the stimulus target alternated from far to near. Artifact-filtered responses were analyzed using Zernike mode computation up to the 6th Zernike radial order. Refractive power components, depth-of-focus (DoF), visual Strehl ratio-based visual acuity estimates and other salient parameters were also computed as time-series. Correlational analysis was performed between all measured parameters. Far and near visual acuity and refractions were monitored throughout the study on all subjects.


While MRSE and distance visual acuity remained unchanged throughout the post-operative period, mean distance-corrected near visual acuity (DCNVA) improved from logMAR 0.6 (20/80) to logMAR 0.21 (20/32); mean uncorrected near visual acuity (UCNVA) improved from logMAR 0.7 (20/100) to logMAR 0.25 (20/35). Optical wavefront data were reliably obtained for all subjects. Wavefront-based predicted visual acuity showed high correlation with published earlier regression results between wavefront higher-order RMS and image quality metrics. Spherical accommodative shift, as determined by M- and Z20- modes, increased in magnitude relative to pre-operative values. More significantly, dynamic COAS time-series analysis showed substantial changes over the post-operative duration in expansion of DoF (as calculated at the 50% cut-off of the through-focus visual Strehl optical transfer function (VSOTF)), and increase of negative spherical aberration with accommodative effort.


Near visual acuity improvements after scleral implant surgery appear to be related to substantial changes in higher-order wavefront structure (primarily spherical aberration), expanded depth-of-focus, and a partial restoration of the spherical accommodative shift lost to presbyopia. This small prospective cohort of scleral implant study patients show changes in objectively-measured pre- vs post-op optical behavior, which are dynamic in nature, and whose metrics parallel observed near visual acuity improvements.

Financial Interest:

One or more of the authors... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented

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