Mixed Astigmatism
Conditions
Keywords
Astigmatism, Mixed astigmatism, FS-LASIK, TransPRK
Brief summary
Mixed astigmatism is a type of refractive error in which the two principal steep and flat meridians focus the light in front and behind the retina, respectively.1 Laser vision correction (LVC) for mixed astigmatism is challenging as it involves a bitoric ablative pattern to flatten the steepest meridian and steepen the flattest one. The aim of the current study was to compare the visual and refractive outcomes of FS-LASIK versus single-step TransPRK for treatment of patients with mixed astigmatism.
Interventions
PROCEDUREFemtosecond laser-assisted LASIK
Patients in the FS-LASIK group underwent flap creation using the femtosecond laser WaveLight FS200® (Alcon lab, TX, USA). After flap creation, wave-front optimized stromal ablation was performed with WaveLight EX-500 (WaveLight®; Alcon Laboratories, Fort Worth, TX, USA) for mixed astigmatism correction.
PROCEDURESingle-step transepithelial PRK
Patients in the single-step TransPRK group underwent StreamLight® PRK in WaveLight EX-500 Excimer laser (WaveLight®; Alcon Laboratories, Fort Worth, TX, USA). In a single step, epithelial ablation (based on epithelial mapping) followed by stromal ablation for mixed astigmatism correction, were accomplished.
Sponsors
Assiut University
Study design
Observational model
COHORT
Time perspective
RETROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
No
Inclusion criteria
* Mixed astigmatism (Plus sphere up to +4 diopters D and a minus cylinder up to -6 D). * Stable refraction. * Clear cornea. * Normal corneal tomography.
Exclusion criteria
* Corrected distance visual acuity worse than 20/32 Snellen's acuity. * Difference between manifest and cycloplegic refraction ≥ 1 D. * Previous corneal or ocular surgeries, other ocular diseases. * Systemic diseases including diabetes mellitus and autoimmune diseases.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Uncorrected distance visual acuity (UDVA) | 24 months | Visual acuity measurement using Snellen's Acuity Chart converted to logMAR notation. |
| Corrected distance visual acuity (CDVA) | 24 months | Corrected visual acuity measurement using Snellen's Acuity Chart and converted to logMAR notation. |
| Postoperative refraction | 24 months | Manifest sphere and cylinder measured by Topcon Auto-Keratorefractometer |
Countries
Egypt
Outcome results
None listed