Efficacy and safety of transepithelial photorefractive keratectomy combined with accelerated corneal cross-linking for refractive error in thin or irregular cornea

Objective

To evaluate the efficacy and safety of transepithelial photorefractive keratectomy (Trans-PRK) combined with accelerated corneal cross-linking (CXL) for refractive error in patients with thin or irregular corneas, excluding keratoconus.

Methods

An observational case series study was performed.Fifty-five right eyes of 55 myopic patients diagnosed with thin or irregular corneas, who underwent Trans-PRK combined with prophylactic CXL surgery, were included at Baotou Chaoju Eye Ophthalmic Hospital from August 2017 to July 2018.Uncorrected distance visual acuity (UDVA) of the operated eye was measured using international standard visual acuity charts, and refractive diopters were measured by computer and comprehensive refraction before surgery and at 1 week, 1, 3, 6, and 12 months after surgery.Corneal morphology was assessed with the Pentacam anterior segment analyzer before surgery and at 3, 6, and 12 months after surgery.Intraocular pressure (IOP) was measured with a non-contact tonometer before surgery and at 1, 3, 6, and 12 months after surgery.The incidence of postoperative complications was recorded.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Baotou Chaoju Ophthalmic Hospital (No.btcj-u-1). Written informed consent was obtained from each subject.

Results

Preoperative, 1-week, 1-, 3-, 6-, and 12-month postoperative UDVA (LogMAR) were 0.52(0.55, 0.78), 0.22(0.12, 0.17), 0.10(0.04, 0.07), 0.00(-0.04, -0.16), -0.08(-0.05, -0.03) and -0.08(-0.06, -0.04), respectively, showing a statistically significant overall difference (Z=249.44, P<0.001). UDVA at each postoperative time point was improved compared to preoperative, and UDVA at 3, 6, and 12 months postoperatively was significantly improved compared to 1 week and 1 month postoperatively (all at P<0.001). The spherical diopter at each postoperative time point decreased significantly compared to preoperative, with the spherical diopter at 1, 3, 6, and 12 months postoperatively being lower than that at 1 week postoperatively, and the 12-month postoperative spherical diopter being lower than that at 3 and 6 months postoperatively, showing statistically significant differences (all at P<0.001). The cylindrical degree at 1, 3, 6, and 12 months postoperatively was lower than that at preoperative and 1 week postoperatively, with statistically significant differences (all at P<0.05). After the operation, the spherical equivalent of the operated eye gradually decreased with time, tending toward emmetropia.The spherical equivalent at each postoperative time point decreased compared to preoperative, with the spherical equivalent at 1, 3, 6, and 12 months postoperatively being lower than that at 1 week postoperatively, and the spherical equivalent at 12 months postoperatively being lower than that at 3 and 6 months postoperatively, showing statistically significant differences (all at P<0.001). The corneal K1 and K2 values at 3, 6, and 12 months postoperatively were significantly lower than preoperatively (all at P<0.001), and the corneal K1 and K2 values at 3 months postoperatively tended to stabilize.The IOP of the operated eye at 3, 6, and 12 months postoperatively was significantly lower than preoperatively, and the IOP at 6 and 12 months postoperatively was lower than that at 1 and 3 months postoperatively, with statistically significant differences (all at P<0.001). One eye developed grade 0.5 corneal haze at 1 week postoperatively, which spontaneously resolved to transparency at 1 month postoperatively.

Conclusions

Trans-PRK combined with accelerated CXL has good efficacy, stability and safety for refractive error patients with thin or irregular corneas, except for keratoconus.

Refractive error; Corneal surgery, laser; Corneal cross-linking; Transepithelial photorefractive keratectomy; Treatment outcome; Safety