https://www.selleckchem.com/products/as1842856.html ncreasing the IVC rate compared to distance learning. It also promotes positive changes in attitudes to this prophylactic procedure, which is why it should be recommended for wider implementation. Med Pr. 2020;71(6)665-85. To assess post-operative outcomes following photorefractive keratectomy (PRK) in patients with posterior corneal steepening compared to an age, gender and refraction matched control group. A retrospective matched case-control study that analysed outcomes of PRK in eyes with posterior corneal steepening as shown by the Sirius tomography (Sirius, CSO, Italy), versus normal eyes. Both groups were age, gender and refraction matched. Data collected include demographic data, pre-operative and post-operative refraction, uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), maximal ablation depth. Inferior-superior ratio, central corneal thickness (CCT), mean posterior keratometry (K), Baiocchi Calossi Versaci index for the front (BCV ) and back (BCV ) cornea, the symmetry index of front (SI ) and back (SI ) corneal curvature were assessed pre- and postoperatively. Overall, 89 study eyes and 954 normal myopic eyes were included. Compared to the control group, corneas with posterior steepening demonstrated significantly reduced CDVA (p < 0.0001 and p = 0.007) and lower CCT (p < 0.0001 and p = 0.03), before and following the operation, respectively. Pre-operative BCV , BCV , SI and SI were significantly higher in corneas with posterior steepening (p < 0.0001) and remained higher following the surgery except for BCV . Ectasia occurred in one eye (1.1%). The safety and efficacy indices at 12 months were comparable for both groups. PRK on corneas with posterior steepening results in similar refractive outcomes compared to normal eyes, 1 year following the surgery. Keratectasia is a rare, however a possible complication. PRK on corneas with posterior steepening results in simil