Table 2. Outcomes of t-PRK alone or combined t-PRK and CXL in treatment of keratoconus.

Author & year	Study design & number of eyes	Techniques	Follow-up	Outcomes	Complications
Kymionis et al (2010)[35]	Case report; 1 eye	Transepithelial phototherapeutic keratectomy followed by corneal CXL	6mo	Significant improvement in UCVA and spectacle corrected visual acuity along with corneal topography. Topography remained stable, six months postoperatively.	Clear cornea without any haze formation
Fadlallah et al (2011)[36]	Comparative case series; 50 eyes (study group) and 50 eyes	t-PRK (study group) and conventional PRK (control group)	3mo	Pain score 2.0 in the study group and 4.5 in the control group. Faster epithelial healing and better UDVA in the study group.	Corneal haze significantly less in the study group
Mukherjee et al (2013)[37]	Prospective pilot study; 22 eyes (control group)	t-PRK and sequential cross-linking	12mo	Significant improvement in visual acuity, refractive outcome, and topographic parameters. Keratometric values were stable postoperatively.	Three eyes developed mild haze and one developed moderate haze.
Ahmet et al (2018)[38]	Retrospective study; 46 eyes	Simultaneous topography-guided t-PRK and accelerated corneal CXL	2y	UDVA, CDVA, corneal topography improved considerably. Keratoconus progression not observed in any patient.	No clinically significant complication observed in any patient. No patient lost more than two lines of CDVA
Xi et al (2018)[39]	Retrospective study; 47 eyes	t-PRK	6mo	UDVA and CDVA both improved	No patients lost two or more lines of CDVA

CXL: Collagen cross-linking; PRK: Photorefractive keratectomy; UDVA: Uncorrected distance visual acuity; CDVA: Corrected distance visual acuity; t-PRK: Transepithelial keratectomy.