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Evaluation of visual outcome and high order aberrations after correcting myopia with or without astigmatism with a new variable spot scanning ablation

Session Details

Session Title: Surface Ablation I

Session Date/Time: Sunday 06/10/2013 | 08:00-09:30

Paper Time: 08:30

Venue: Main Lecture Hall (Ground Floor)

First Author: : M.Khalifa EGYPT

Co Author(s): :    M. Shafik Shaheen              

Abstract Details


To analyze the visual outcome and the induced changes of ocular high order aberrations (HOA’s) after the correction of myopia with or without astigmatism with a Variable Spot Scanning (VSS) Refractive ablation.


Horus Vision Correction Center, Alexandria, Egypt.


This study is a prospective consecutive enrolment study, which included 50 myopic eyes of 25 patients with myopia -1.0 to -10.0 D. of spherical equivalent with or without astigmatism up to 2.75 D. Each eye had LASIK using Moria M2 microkeratome (Moria) and Star S4 IR excimer laser (Abbott Medical Optics, Santa Ana, CA) using the new manifest refraction based VSS Refractive procedure, which uses a variable spot size and variable repetition rate to reduce thermal effects. Visual outcome was evaluated preoperatively and 3 months after surgery including contrast sensitivity (CS) measured with the CVS-1000 (Vector Vision, Greenville, OH) and HOA’s measured with the I-Design aberrometer (Abbott Medical Optics, Santa Ana, CA), with pupil diameter 4 mm used for the treatment calculation and 5 mm pupil diameter for comparison of preoperative and postoperative HOA RMS.


Mean age was 36.2 years (±11.8), females were 64% and males were 36%. Mean preoperative MRSE was -2.94 D (-1.0 to -9.0) and mean preoperative cylinder was -0.78 D (0.0 to -2.75). After 3 months, 82% of eyes were within 0.5 D. and 92% were within 1.0 D of MRSE, monocular UCVA was 1.0 in 74% and 0.8 in 96% of eyes. There were 4 eyes gained one line and one eye lost one line of BCVA. Mesopic contrast sensitivity showed no significant difference in all frequencies. There was minimal non significant shift of the spherical aberration in the positive direction ( mean of change 0.07± 0.09 ?m), which had no correlation with the amount of myopia corrected.


The new technique of variable spot scanning ablation was safe, effective, and predictable in correcting myopia with or without astigmatism. The induction of some spherical aberration was minimal and non-significant and interestingly not correlated with the amount of corrected myopia.

Financial Interest:

... research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented

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