Abstract
Abstract: :
Purpose: To evaluate VISX's multi-focal presbyopic correction. The target was for patients to perform all normal daily tasks without corrective lenses. The objective measurement method was required because the treated eye must see both near and distance uncorrected, simultaneously. Methods: The ideal target is simultaneous 0.0 LogMAR for distance vision and 0.0 LogMAR for near vision, or better. A new notion is to represent this two dimensional measurement by DANA{x,y}(Distance & Near Acuity) in units of {LogMAR, LogMAR}. The DANA representation provides the eye's distance and near acuity, but because the DANA values map into a 2 dimensional space, a simplifying concept is required, which begins by defining a family of lines with minus-one slope intersecting the values DANA{i,i}, with another term, SAR(i) (Simultaneous Acuity Rating) where i is a real number. The SAR(i) values represent depth range. The families of lines are defined as: NearAcuity = -DistanceAcuity +2i, where i is the SAR index. Any DANA value can be converted to SAR index. The distance between two adjacent SAR indices in DANA space is √2 in units of LogMAR. Eight myopic and 12 hyperopic eyes received an investigational presbyopic treatment combined with a distance vision treatment on a VISX STAR S3. Each patient received comprehensive eye exams and were evaluated pre-op and post-op at 1week, 1, 3, 6, and 12 months. Pre- and post-op topographies were taken to evaluate the eye’s response to the ablations. Difference maps between pre-op and 3 months were analyzed for shape factor and compared to the effectiveness evaluations. Results: Average uncorrected distance acuity increased by 8 lines. Final average distance acuity was -0.03 ± 0.07 LogMAR. The presbyopic surface did not interfere with the distance correction. Average near vision acuity increased by 2 lines. Final average near acuity was 0.29 ± 0.17 LogMAR. Near-vision comparison was made between pre-surgery distance-adjusted near vision (distance manifest included) and post-surgery uncorrected near vision. Simultaneous vision acuity rating increased by 5.5 lines. Four of the 9 patients’ results were good to excellent. Average DANA for the 4 patients was (-0.03, 0.14) which equals an SAR of 0.06, which equals 20/20+1 distance and 20/25+1 near vision. Conclusions: The VISX presbyopic multi-focal correction performed well. With refinements it will allow presbyopes to function without glasses or contacts. The objective test method correlated well with patients’ subjective, positive assessments of post-op vision.
Keywords: refractive surgery • refractive surgery: LASIK • visual acuity