Early Visual, Refractive, and Astigmatism Vector Outcomes of StreamLight Trans-PRK for High Astigmatism (≥ 2.00 D).

Abstract

Objective: To report the early refractive, visual, and astigmatic-vector outcomes of single-step StreamLight™ transepithelial photorefractive keratectomy (Trans-PRK) on the WaveLight EX500 platform in eyes with high preoperative astigmatism (≥ 2.00 dioptres, D).

Methods: Single-centre cohort study of 171 consecutive eyes of 107 patients (mean age 27.87 ± 6.56 years; 37.4% female) treated by a single surgeon. Astigmatic outcomes were analyzed by the Alpins method at the corneal plane. A subset of 57 eyes with a mean follow-up of 10.3 ± 7.4 months underwent stability sub-analysis.

Results: Mean preoperative cylinder was 3.29 ± 0.81 D and mean spherical equivalent (SE) was -2.73 ± 2.56 D. At one month, mean UDVA was 0.05 ± 0.09 logMAR, mean residual cylinder was 0.65 ± 0.44 D, and mean SE was -0.22 ± 0.47 D. SE was within ±0.50 D of intended in 71.3% of eyes; cylinder was ≤ 0.50 D in 53.2%. Mean efficacy and safety indices were 1.04 ± 0.22 and 1.10 ± 0.22, respectively, with no eye losing two or more lines of CDVA. Vector analysis yielded a correction index of 1.09 ± 0.16, an index of success of 0.21 ± 0.14, and 99% of eyes within ±15° of the intended axis. Stability sub-analysis showed minimal change in SE and an unchanged cylinder between 1 month and a mean follow-up of 10.3 ± 7.4 months (SE -0.14 to -0.07 D).

Discussion: Trans-PRK delivered good early visual, refractive, and astigmatic vector outcomes. Axis precision was high with a mean angle of error of -0.81 ± 5.32°, 80% of eyes within ±5°, and 99% within ±15° of the intended axis. Interpretation of vectorial results is subject to the specificity of the 1-month post-Trans-PRK central epithelial thickness (CET decreases in the first week, returns to baseline at 1 month, and progressively increases up to 6 months).

Conclusions: Single-step StreamLight™ Trans-PRK on the WaveLight EX500 platform achieves favorable early refractive, visual, and vector-analytic outcomes in eyes with high preoperative astigmatism, with corneal-plane vector parameters that compare favorably with those reported in the published Trans-PRK literature.