Clinical outcomes of Transepithelial photorefractive keratectomy to treat low to moderate myopic astigmatism

Abstract

Background: To evaluate the refractive and visual outcomes of Transepithelial photorefractive keratectomy (TransPRK) in the treatment of low to moderate myopic astigmatism.

Methods: This retrospective study enrolled a total of 47 eyes that had undergone Transepithelial photorefractive keratectomy. Preoperative cylinder diopters ranged from - 0.75D to - 2.25D (mean - 1.11 ± 0.40D), and the sphere was between - 1.50D to - 5.75D. Visual outcomes and vector analysis of astigmatism that included error ratio (ER), correction ratio (CR), error of magnitude (EM) and error of angle (EA) were evaluated.

Results: At 6 months after TransPRK, all eyes had an uncorrected distance visual acuity of 20/20 or better, no eyes lost ≥2 lines of corrected distant visual acuity (CDVA), and 93.6% had residual refractive cylinder within ±0.50D of intended correction. On vector analysis, the mean correction ratio for refractive cylinder was 1.03 ± 0.30. The mean error magnitude was - 0.04 ± 0.36. The mean error of angle was 0.44° ± 7.42°and 80.9% of eyes had axis shift within ±10°. The absolute astigmatic error of magnitude was statistically significantly correlated with the intended cylinder correction (r = 0.48, P < 0.01).

Conclusions: TransPRK showed safe, effective and predictable results in the correction of low to moderate astigmatism and myopia.

Keywords: Astigmatism; Myopia; Transepithelial photorefractive keratectomy.

Fig. 1

Basic astigmatic vector quantities and relationships. EA: Error of angle; EV: Error vector; EM: Error of magnitude; IRC: Intended refractive correction; SIRC: Surgically induced refractive correction

Fig. 2

Comparison of preoperative corrected distance visual acuity (CDVA) and postoperative uncorrected distance visual acuity (UDVA) (a). Change in snellen lines of CDVA at 6 months postoperatively (b)

Fig. 3

Levels of astigmatism before (a) and after (b) transepithelial photorefractive keratectomy

Fig. 4

Achieved versus attempted spherical equivalent corrections 6 months postoperatively (a). Achieved versus attempted astigmatism corrections 6 months postoperatively (b). The red solid line indicates the outcome of linear regression analysis, the area between two dotted lines mean within ±0.50D

Fig. 5

Scatter diagram of Error Angle (EA) for 47 eyes (A). Summary of the EA between the achieved treatment and the intendent treatment