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Higher-Order Aberrations, Corneal Density, and Visual Acuity After Excimer Laser Phototherapeutic Keratectomy (PTK)
Simon Helm1, Johanna Wiedemann1, Benjamin Rosswinkel2
1Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
Background:
To evaluate visual acuity outcome after excimer laser phototherapeutic keratectomy (PTK) for epithelial basement membrane dystrophy (EBMD) and to provide new insights into higher-order aberrations (HOAs) and corneal density changes.
Methods:
In this single-center cohort, 92 eyes from 80 individuals underwent PTK for EBMD, with follow-up durations reaching up to 7.5 years (mean 332 ± 526.5 days).
Results:
Mean BCVA in EBMD improved by 0.17 ± 0.17 logMAR (p < 0.001) for patients without visual acuity limitations and by 0.14 ± 0.31 (p = 0.004) logMAR if patients had additional visual acuity limitations. Refraction remained stable after PTK. HOA reduced by 0.16 ± 0.23 μm (p < 0.001), corneal density by 6.73 ± 11.83 gray scale units (p < 0.001), and K max by 1.02 dpt (±2.73) (p = 0.006) after PTK. A correlation before and after PTK between HOA (p = 0.014 and 0.002), corneal density (p < 0.002), and K max (p = 0.010) with BCVA was observed. Light haze occurred in 10% of the cases. Re-PTK was necessary for 1 patient (1.1%).
Conclusion:
PTK significantly enhances visual acuity in patients with EBMD, independently of additional visual acuity limitations. The significant reduction of HOA, corneal density, and K max as well as the correlation of these parameters with visual acuity prove an effective therapy on an objective level.
