Related Experiment Video
Updated: Jul 8, 2025
Author Spotlight: Advancements in Refractive Surgical Correction for Presbyopia and Exploring Postoperative Visual Acuity
Published on: September 20, 2024
Vector Analysis and Prognostic Factors for Femtosecond Arcuate Keratotomy in Post-Keratoplasty Astigmatism
Bayan A Alsaif1, Abdulaziz Al Somali2, Sumayah H Banaji1
1Department of Ophthalmology, College of Medicine, King Fahd Hospital of the University, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.
Purpose:
To analyze different tomographic and refractive parameters for predicting successful visual outcome following femtosecond laser-assisted arcuate keratotomy (FSAK) for post-keratoplasty astigmatism.
Design:
Retrospective.
Methods:
Retrospective study evaluating patients with astigmatism following penetrating keratoplasty (PKP) or deep anterior lamellar keratoplasty (DALK) who underwent FSAK. Vector analysis using the Alpins method was done to calculate surgically induced astigmatism (SIA). An improvement of 3 lines of Early Treatment Diabetic Retinopathy Study (ETDRS) lines was used for successful outcome. Outcome was measured at 3 months and 17 months.
Results:
This study included 106 eyes from 104 patients (65 males and 39 females). Mean age was 31.8±8.6 years, and 89.4% (n=93) of cases were keratoconus (KC), 3.8% (n=4) scar, 3.8% (n=4) granular dystrophy, 1.9% (n=2) post-LASIK ectasia, and 1.0% (n=1) macular dystrophy. Uncorrected visual acuity (UCVA) improved from 1.02±0.53 logarithm minimal angle of resolution (logMAR) to 0.87±0.49 logMAR (p=0.01) at 3 months and to 0.92±1.08 logMAR (p=0.57) at 17 months. Best spectacle-corrected visual acuity (BSCVA) improved from 0.41±0.30 logMAR to 0.31±0.19 logMAR (p<0.01) at 3 months and to 0.23±0.27 logMAR (p<0.01) at 17 months. Success was achieved in 50% (n=53) and 49% (n=52) at 3 and 17 months follow-up, respectively. Success group showed worse preoperative UCVA (1.21±0.56 vs 0.83±0.44 logMAR; p<0.01), worse preoperative BSCVA (0.50±0.36 vs 0.33±0.19 logMAR; p=0.01). Preoperative UCVA had an area under the curve of 0.721 (95% CI: 0.622-0.820; p< 0.01). The Youden's optimal cutoff point was 0.90 logMAR (equivalent Snellen 20/159) with 76.9% sensitivity and 35.2% specificity. Flattening index (FI) was 87% in DALK and 73% in PKP (p=0.14). Correction index (CI) was 99% and 86% (p=0.18) for DALK and PKP, respectively. Success of the astigmatic surgery for DALK and PKP was 44% vs 42% (p=0.29), respectively.
Conclusion:
Improvement of at least three lines was achieved in 49% of patients who underwent FSAK following PKP or DALK; this improvement was achieved in patients who had a worse preoperative UCVA.
