Myopic regression after photorefractive keratectomy: a retrospective cohort study

Abstract

Background: Myopic regression is a major complication of photorefractive keratectomy (PRK). The rates and causes vary considerably among different studies. This study aimed to investigate myopic regression at six months after myopic PRK.
 Methods: In this retrospective cohort study, we included all eligible patients with myopia ranging from - 0.75 to - 9 D, aged 18 to 50 years, who underwent PRK by a single surgeon with the availability of preoperative and postoperative data at six months after the initial procedure. All participants underwent comprehensive ophthalmic examinations preoperatively and at six months post-PRK. Overcorrection was planned based on the participant’s age range to achieve the desired refractive result after PRK. All patients received the same postoperative antibiotic and steroid eye drops in a similar dosage regimen, and the contact lenses were removed after complete corneal epithelial healing. Based on the spherical equivalent of refraction six months after PRK, eyes without and with myopic regression were allocated into groups 1 and 2, respectively.
 Results: We included 254 eyes of 132 patients who underwent myopic PRK with a mean (standard deviation) age of 30.12 (7.48) years; 82 (62.12%) were women and 50 (37.88%) were men. The frequency of myopic regression was significantly lower in patients with younger age, lower preoperative cylindrical refraction, and lower ablation depth (all P < 0.05). Overcorrection was more successful in eyes with low myopia than in eyes with high myopia (P < 0.05). The highest frequency of myopic regression occurred in eyes with moderate myopia (25.68%), followed by eyes with high myopia (20.0%) and low myopia (6.54%). Among different age groups, patients aged less than or equal to 30 years had a lower frequency of myopic regression. The frequency of myopic regression in the different age groups was 5.0% at 18-20 years, 7.46% at 26-30 years, 12.28% at 21-25 years, 21.31% at 31-35 years, and 26.53% at 36-50 years.
 Conclusions: Overcorrection was more successful in eyes with low myopia than in eyes with high myopia. The success rate was higher in younger patients with lower astigmatism and ablation depths. Myopic regression was most frequent in eyes with moderate myopia, followed by those with high and low myopia. Further studies should replicate our findings over a longer follow-up period with a larger sample size before generalization is warranted.

Safety and efficacy of implantable phakic contact lens versus implantable collamer lens in myopia correction

“… Abbreviations: UCDVA, uncorrected distance visual acuity; BCDVA, best-corrected distance visual acuity; SE, spherical equivalent; n, number of eyes; Q2, the second quartile; Q3, the third quartile; D, diopters. Note: P -values < 0.05 are shown in bold; Follow-up comparisons within each group were performed using the Friedman test with notation as a P -value; Pairwise comparisons between two follow-ups were performed using the Wilcoxon matched-pairs signed rank test with notation as b P -value; The two groups were compared using the Mann – Whitney U test with notation as c P -value; The implantable collamer lens (ICL) group comprised 100 eyes of 100 individuals who underwent ICL implantation (ICL Model V4c; STAAR Surgical Co., Nidau, Switzerland); The implantable phakic contact lens (IPCL) group comprised 100 eyes of 100 individuals who underwent IPCL implantation (IPCL V2 model; Care Group, Baroda, India); The SE was calculated in D using the spherical component of the refined subjective refraction plus one-half the cylindrical component [ 16 ] . …”

“…Employing the trial frame, refraction was then subjectively refined, and the best-corrected distance visual acuity (BCDVA) was recorded in decimal notation using a Snellen chart. The spherical equivalent (SE) was calculated in D using the spherical component of the refined subjective refraction plus one-half the cylindrical component [ 16 ]. IOP was measured using an air puff tonometer (CT-80; Topcon Corp.).…”