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Updated: May 12, 2026

Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile

Published on: September 20, 2024

Changes in spherical aberration after various corneal surface ablation techniques.

Hyun Seok Ahn¹, Jae Lim Chung, Eung Kweon Kim

¹S-Eye Center, Ansan, Korea.

Korean Journal of Ophthalmology : KJO

|April 2, 2013

Summary

Corneal spherical aberration (SA) changes after refractive surgery differ by procedure. Photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK) induced significant SA shifts, while phototherapeutic keratectomy (PTK) showed a decrease.

Keywords:

Aberration Laser epithelial keratomileusis Photorefractive keratectomy Phototherapeutic keratectomy

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Last Updated: May 12, 2026

Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile

Published on: September 20, 2024

$Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter$

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Published on: September 16, 2025

Area of Science:

Ophthalmology
Corneal Surgery
Refractive Error Correction

Background:

Refractive surgical procedures can alter corneal shape, impacting both visual acuity and higher-order aberrations like spherical aberration (SA).
Understanding these induced changes is crucial for predicting visual outcomes and optimizing surgical techniques.

Purpose of the Study:

To evaluate and compare the changes in corneal spherical aberration (SA) following three distinct surface ablation techniques: phototherapeutic keratectomy (PTK), myopic photorefractive keratectomy (PRK), and myopic wavefront-guided laser epithelial keratomileusis (LASEK).

Main Methods:

A comparative study involving 26 eyes (PTK), 26 eyes (PRK), and 34 eyes (LASEK).
Corneal SA was measured preoperatively and 6 months postoperatively using the iTrace aberrometer.

Main Results:

Six months post-surgery, mean corneal SA was -0.173 µm (PTK), 0.672 µm (PRK), and 0.143 µm (LASEK).
The mean change in corneal SA (ΔSA) was -0.475 µm for PTK, +0.402 µm for PRK, and -0.143 µm for LASEK.

Conclusions:

The magnitude and direction of surgically induced corneal spherical aberration vary significantly depending on the specific surface ablation procedure employed.
Predicting these SA alterations is essential for refining future refractive surgery algorithms and enhancing visual quality.