Photorefractive Keratectomy Eyes Research Articles

Surgical options and clinical outcomes for high myopia.

Higher degrees of myopia are currently being treated with refractive surgery. However, there is limited characterization and outcomes data for this cohort. This article aims to review the literature on highly myopic patients who had refractive surgery and present a retrospective analysis of 149 patients (270 eyes) with high to extreme myopia (≤-5.0D SE) who underwent refractive surgery [laser-assisted subepithelial keratomileusis (LASIK), photorefractive keratectomy (PRK), or implantable collamer lense (ICL)] at a single practice. There is substantial literature on the efficacy of LASIK, PRK, and phakic intraocular lenses for refractive error correction, but a dearth of studies on patients with high to extreme myopia undergoing different types of refractive surgery. Our study reveals that this cohort of patients has excellent outcomes with minimal complications. Our study reveals that the average preoperative myopia was highest in ICL patients (-10.03D), followed by PRK (-7.21D), and LASIK (-7.04D) patients. Not surprisingly, eyes with high myopia and thin corneas were offered and elected ICLs for their procedure. Highly myopic patients achieved outcomes consistent with data reported in the literature- average postoperative uncorrected visual acuity was 20/20 for LASIK and ICL eyes and 20/25 for PRK eyes.

Long-term results of hyperopic ablations using alcohol-assisted PRK and FS-LASIK: comparative study.

To evaluate the long-term visual and refractive outcomes of hyperopic excimer ablation using alcohol-assisted photorefractive keratectomy (PRK) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). American University of Beirut Medical Center, Beirut, Lebanon. Retrospective, matched comparative study. Eyes that underwent alcohol-assisted PRK were compared to matched eyes that underwent FS-LASIK. All patients were followed up for at least 3 years after surgery. The refractive and visual outcomes of each group were compared at different postoperative time points. The main outcome measures were spherical equivalent deviation from target (SEDT), manifest refraction, and visual acuity. 83 eyes underwent alcohol-assisted PRK and 83 matched eyes underwent FS-LASIK. Preoperative manifest refraction spherical equivalent was 2.44 ± 1.18 diopters (D) and 2.20 ± 0.87 D ( P = .133) in the PRK and FS-LASIK groups, respectively. Preoperative manifest cylinder was -0.77 ± 0.89 D and -0.61 ± 0.59 D ( P = .175) for the PRK and LASIK groups, respectively. 3 years postoperatively, SEDT was 0.28 ± 0.66 D and 0.40 ± 0.56 D for the PRK and LASIK groups, respectively ( P = .222), whereas manifest cylinder was -0.55 ± 0.49 D and -0.30 ± 0.34 D for PRK and LASIK, respectively ( P < .001). The mean difference vector was 0.59 ± 0.46 for PRK and 0.38 ± 0.32 for LASIK ( P < .001). 13.3% of PRK eyes and 0% of LASIK eyes had >1 D of manifest cylinder ( P = .003). Both alcohol-assisted PRK and FS-LASIK are safe and effective for the treatment of hyperopia. PRK induces slightly more postoperative astigmatism than LASIK. Larger optical zones and recently introduced ablation profiles that lead to a smoother ablation surface might improve the clinical results of hyperopic PRK.

Effects of mitomycin-C on tear film function following photorefractive keratectomy for mild-to-moderate myopia

Background: Mitomycin C (MMC) is used to prevent corneal opacity after photorefractive keratectomy (PRK). This study sought to determine the effect of MMC on tear film function after PRK in eyes with mild-to-moderate myopia.Methods: This prospective, contralateral eye comparison was conducted on 30 eyes of 15 patients with low-to-moderate myopia referred to Alzahra Eye Hospital, Zahedan, Iran. The eyes of the control group underwent PRK with a balanced salt solution, while the fellow eyes in the intervention group underwent PRK with 0.02% MMC for 25 s. The tear breakup time test (TBUT) and basic Schirmer test results of eyes in the control and intervention groups were compared at baseline and 1, 3, and 6 months postoperatively. Tear osmolarity was recorded and compared at baseline and 3 months postoperatively. Results: The mean ± standard deviation (SD) age of participants was 27.53 ± 7.04 years. No statistically significant differences were observed in the means ± SDs for tear osmolarity, TBUT, and basic Schirmer test values (all P &gt; 0.05) between MMC-treated eyes and untreated fellow eyes at baseline and during postoperative follow-up. The means ± SDs for tear osmolarity, TBUT, and basic Schirmer test results were comparable in both groups between the baseline and postoperative follow-ups (all P &gt; 0.05). Conclusions: Single application of a standard dose of MMC (0.02%) for 25 s in PRK did not change tear stability, tear production, or variation in tear dynamics up to 6 months postoperatively in eyes with low-to-moderate myopia. Future longitudinal studies with a longer follow-up and a larger sample size are warranted to confirm our findings.

LASIK versus PRK for high astigmatism.

To compare the refractive outcomes of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for myopic astigmatism of 3 diopters (D) or more. Retrospective matched comparative study. This study include consecutive myopic patients (SE 0 to -10 D) undergoing LASIK or PRK between 2007 and 2016 with astigmatism of 3 to 6 D, and postoperative follow-up of at least 30days for LASIK and 60days for PRK, compared outcomes of LASIK and PRK eyes. The LASIK and PRK groups comprised 175 eyes of 175 patients each, with median follow-up of 39 and 139days, respectively (P < 0.001). Mean preoperative manifest astigmatism was -3.35 ± 0.46 and -3.42 ± 0.51 D (P = 0.92), postoperative SE was -0.43 ± 0.55 and -0.16 ± 0.64 D (P < 0.001), and arithmetic astigmatism was -0.59 ± 0.46 and -0.88 ± 0.60 D (P < 0.001), for the LASIK and PRK groups, respectively. Fifty-seven and 64.0% eyes had postoperative SE within ± 0.5 D of emmetropia (P = 0.19), and 57.7 and 38.8% eyes were within 0.5 D of attempted astigmatic correction (P < 0.001) for the LASIK and PRK groups, respectively. More PRK eyes were overtreated regarding both SE and astigmatism than LASIK eyes (P < 0.001). The efficacy and safety indices were close to 1.0 in both groups. The surgically induced astigmatism, magnitude of error, index of success, correction index and flattening index were all better in the LASIK group. Both LASIK and PRK achieve good outcomes in high astigmatism. LASIK achieved mild superiority over PRK.

Long Term Follow-Up Safety and Effectiveness of Myopia Refractive Surgery.

(1) Background: Refractive surgery is an increasingly popular procedure for decreasing spectacle or contact lens dependency. The two most common surgical techniques to correct myopia are photorefractive keratectomy (PRK) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). This study demonstrates the long-term effectiveness, safety, and predictability of both techniques for the refractive surgery of myopia. (2) Methods: A retrospective non-randomized study was performed. We followed 509 PRK eyes and 310 FS-LASIK surgeries for ten years. Patients were followed-up after 3 months and after 1, 2, 5, and 10 years, gathering data on their uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA). The safety index of both procedures was defined as the quotient between the postoperative BCVA and the preoperative BCVA. We defined a procedure as safe if this quotient was equal to or greater than 1. The effectiveness index was calculated as the quotient between postoperative UCVA divided by the preoperative BCVA. (3) Results: The safety index was higher than 1 (1.09) and an effectiveness index of 0.82 after ten years of surgery in both groups was found. (4) Conclusion: These data demonstrated excellent safety and effectiveness indices for both techniques, although FS-LASIK is a technique with better safety and effectiveness indices than PRK.

Outcomes of photorefractive keratectomy in patients with posterior corneal steepening.

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 (BCVf) and back (BCVb) cornea, the symmetry index of front (SIf) and back (SIb) 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 BCVf, BCVb, SIf and SIb were significantly higher in corneas with posterior steepening (p < 0.0001) and remained higher following the surgery except for BCVf. 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.

A Review on Different Tonometers for Intraocular Pressure Measurement After Photorefractive Keratectomy or Small Incision Lenticule Extraction.

This paper aims to review different tonometers for intraocular pressure measurement in eyes after photorefractive keratectomy or small incision lenticule extraction. An Entrez Pubmed search was performed on July 19th, 2020. There were 32 eligible articles investigated in the use of tonometers or biomechanical properties of cornea in post photorefractive keratectomy eyes and 11 articles investigated in post small incision lenticule extraction eyes. Corvis ST and dynamic contour tonometry were found to be accurate for intraocular pressure measurement in post photorefractive keratectomy eyes. For post small incision lenticule extraction eyes, Corvis ST was found to be more accurate than other tonometers. Other tonometers such as Goldmann applanation tonometer, noncontact tonometry, Tonopen, ocular response analyzer can also be used in post photorefractive keratectomy or small incision lenticule extraction eyes in clinical practice; however, it is important for ophthalmologists to take note of the chances of discrepancies.

Comparison of single-step transepithelial photorefractive keratectomy and conventional photorefractive keratectomy in low to high myopic eyes.

Purpose:To compare the visual outcome, safety, safety index, efficacy, efficacy index and corneal transparency between single-step transepithelial photorefractive keratectomy (t-PRK) and conventional photorefractive keratectomy (PRK) with manual debridement of epithelium in eyes with low to high simple myopia and compound myopic astigmatism.Methods:In this retrospective ,case control study, we analysed and compared the postoperative uncorrected visual acuity(UCVA), postoperative best corrected visual acuity (BCVA) , safety, safety index,efficacy,efficacy index and the corneal transparency between t-PRK and PRK with 6th-generation Amaris excimer 500E laser (Schwind eye-tech-solutions) in 115 eyes of 59 patients.Results:Preoperative Mean Refractive Spherical Equivalent (MRSE) was - 3.88 + 0.23 Diopters(D) and -4.73 + 0.23D in PRK and t-PRK group respectively(p=0.09). In both the groups , none of the eyes lost postoperative BCVA at the end of mean follow-up period of 3.5 months . All the eyes achieved post operative UCVA of 20/40 or better in both the groups. Incidence of trace corneal haze was high in t-PRK group at the end of 3.5 months (P = 0.003).Conclusion:Single-step t-PRK and PRK provide similar results at the end of mean follow-up period of 3.5 months postoperatively with regards to post-operative UCVA, post operative BCVA, safety, safety index, efficacy and efficacy index. There was high incidence of trace haze in t- PRK eyes. Both the procedures are predictable, effective, and safe for correction of low to high myopia.

Clinical outcomes of mechanical and transepithelial photorefractive keratectomy in low myopia with a large ablation zone

To evaluate the clinical outcomes, vector parameters, and aberrations between mechanical photorefractive keratectomy (PRK) and transepithelial PRK in eyes with low myopia. Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, Korea. Retrospective, comparative case series. Eighty-four eyes of 84 patients with low myopia (≤2.00 diopters) were treated with mechanical or transepithelial PRK (41eyes and 43 eyes, respectively), with the application of alargeoptical zone (OZ). Visual acuity, manifest refraction, slitlampevaluation, autokeratometry, corneal topography, and the evaluation of corneal wavefront aberrations were measured preoperatively and at 1, 3, and 6months after surgery. The efficacy, predictability, vector parameters, corneal aberrations, and safety at 6months after surgery were compared between the two treatment groups. The mean uncorrected distance visual acuity was comparable, at -0.13±0.05 (SD) and -0.15±0.05, in the mechanical and transepithelial PRK groups, respectively, at 6months after surgery. The safety and efficacy indices, vector parameters, and aberrometric values were also comparable between the two groups. The OZ was large in both groups (7.09±0.20mm and 7.12±0.27mm in the mechanical PRK and transepithelial PRK groups, respectively), and showed no significant difference between groups. The corneal total root-mean-square higher-order aberrations and coma significantly reduced after treatment in both groups, and spherical aberrations significantly decreased after transepithelial PRK. Mechanical and transepithelial PRK with a large OZ provided effective and safe outcomes for the correction of low myopia without differences in visual acuity and refractive outcomes between procedures.

Transepithelial photorefractive intrastromal corneal crosslinking versus photorefractive keratectomy in low myopia

To compare the outcomes of transepithelial photorefractive intrastromal corneal crosslinking (CXL) and photorefractive keratectomy (PRK) in eyes with low myopia. Purpan Hospital, Toulouse, France. Prospective case series. Myopic patients with a manifest refraction spherical equivalent (MRSE) of -1.00 to -2.50 diopters (D) and a cylindrical component of plano to -0.75 D were included. The dominant eye had PRK (PRK eyes). The nondominant eye had transepithelial photorefractive intrastromal CXL with riboflavin (ParaCel Part 1 and 2), 30mW/cm2 pulsed ultraviolet-A irradiation centered on the pupil (Mosaic System) for 16minutes and 40seconds, and a supplemental oxygen delivery mask (CXL eyes). The primary outcome measure wasthe change in the MRSE. Other outcome measures werethe uncorrected (UDVA) and corrected (CDVA) distance visual acuities, mean keratometry, and endothelial cell count (ECC) over a 6-month follow-up. Adverse events were assessed. Nineteen patients were included. By 6months, the mean MRSE had decreased by 0.72 D ± 0.42 (SD) in CXL eyes and by 1.35±0.46 D in PRK eyes (P<.001). The mean change in UDVA was -0.35±0.21 logarithm of the minimum angle of resolution (logMAR) in CXL eyes and -0.66±0.19 logMAR in PRK eyes (P<.001). No complications were reported. The change in the ECC and CDVA was not statistically significant. Photorefractive keratectomy provided better visual and refractive outcomes than transepithelial photorefractive intrastromal CXL. Transepithelial photorefractive intrastromal CXL, however, showed the potential refractive effect of CXL but with a limited magnitude of myopic correction.

Long-term evaluation of corneal sub-basal nerve recovery after photorefractive keratectomy and influence of pars plana vitrectomy.

The corneal sub-basal nerve (SBN) plexus is destroyed during photorefractive keratectomy (PRK) and its recovery is still a matter of debate. In vivo confocal microscopy (IVCM) was used to evaluate SBN plexus in 23 patients at a distance of 10-25 years (mean 15.6 years) from myopic PRK. Because 8 out of the 23 PRK patients underwent pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment, IVCM was also performed on those patients 6 months after PPV. Thirteen patients matched for age and myopia served as controls (non-PRK). SBN plexus was markedly reduced after PRK compared with non-PRK eyes and showed a slow, continuous but incomplete recovery up to the end of our follow-up (range 10-25 years). PRK and non-PRK eyes showed a marked reduction in SBN density 6 months after PPV, thus demonstrating a detrimental effect exerted by PPV on SBN plexus.

In Vivo Prediction of Air-Puff Induced Corneal Deformation Using LASIK, SMILE, and PRK Finite Element Simulations.

To simulate deformation amplitude after laser-assisted in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), and photorefractive keratectomy (PRK) with finite element models. Finite element simulations of air-puff applanation on LASIK, SMILE, and PRK models were performed on a cohort of normal eyes, which had undergone refractive treatments. Short- and long-term wound healing responses were considered for SMILE and LASIK models based on evidence of microdistortions in Bowman's layer and crimping of collagen fibers. First, inverse simulations were performed to derive the preoperative properties of the cornea. Using these properties and planned refractive treatment, postoperative air-puff deformation amplitude was predicted and compared with the in vivo measurements. The predicted postoperative corneal stiffness parameters agreed very well with in vivo values of SMILE, LASIK, and PRK eyes. Intraclass correlations (ICC) were greatest in PRK eyes (ICC > 0.95). This agreement was lower for peak deformation amplitude and peak deflection amplitude in SMILE and LASIK eyes (ICC < 0.9). In PRK eyes, peak deformation and deflection amplitude predictions were the best relative to in vivo magnitudes. Also, linear correlation (r) between in vivo measurement and predicted biomechanical parameters indicated strong agreement between them (SMILE: r ≥ 0.89, LASIK: r ≥ 0.83, PRK: r ≥ 0.87). The is the first study to present predictive simulations of corneal deformation changes after different procedures. Patient-specific preoperative corneal biomechanical properties and finite element models were a significant determinant of accurate postoperative deformation amplitude prediction.

Studying the factors related to refractive error regression after PRK surgery

BackgtoundPhotorefractive keratectomy (PRK) is used for a wide range of refractive errors such as low to moderate myopia, hyperopia and astigmatism. While many improvements have been made in laser application and accuracy as well as the modes of corneal flap removal, and although the results are somewhat predictable, regression of refractive errors is still a common complaint among the patients undergoing refractive surgery with Excimer Laser. We aimed to determine related factors of regression following photorefractive keratectomy (PRK) in different types of refractive errors.MethodsThis cross-sectional study included patients who had undergone PRK more than 6 months previously and investigated refractive error regression and related factors. The participants were those who had PRK eye surgery for the first time from 2013 to 2016 using Technolas 217z100. A refraction value of spherical equivalent > 0.75 D after cycloplegic refraction was defined as refractive error regression.ResultsA total of 293 eyes on 150 subjects were studied. The preoperative refractive error of the eyes were as follows: 5.5% were myopic, 1% were hyperopic, 4.8% had astigmatism, 76% had myopic astigmatism and 12.6% had hyperopic astigmatism. Regressed and non-regressed eyes were assessed using the generalized estimating equations for the probabilistic variables of demographic characteristics, topography and eye refraction. The variables of simulated keratometry astigmatism (simK) (OR = 2.8; p = 0.04), 5 mm irregularity (OR = 3.56; p = 0.01) and sphere value (OR = 1.98; p = 0.01) were significantly related to refractive error regression. There was no significant relationship between the regressed and non-regressed eyes of the same person (p ≥ 0.05).ConclusionThere was a positive relationship between the increase of 5 mm irregularity, simK, sphere value before surgery and refractive error regression. Age, sex and type of refraction error of the patient and the expertise of the PRK surgeon could change the general results; therefore, not all cases should be dealt with identically.

Two-year follow-up of corneal cross-linking and refractive surface ablation in patients with asymmetric corneal topography

AimsTo evaluate the safety and efficacy of corneal cross-linking (CXL) followed by photorefractive keratectomy (PRK) for refractive correction in patients with bilateral asymmetric topography.MethodsForty-four patients (88 eyes) were enrolled in...

Comparative analysis of safety and efficacy of photorefractive keratectomy versus photorefractive keratectomy combined with crosslinking.

PurposeTo assess the safety, efficacy, and refractive predictability of half-fluence accelerated corneal collagen crosslinking (CXL) applied concurrently with photorefractive keratectomy (PRK), and compare the results to standard PRK.SettingRefractive Services, The Eye Foundation, Coimbatore, India.DesignInterventional comparative case series.MethodsPatients seeking refractive correction for myopia or myopic astigmatism were included in the study. Photorefractive keratectomy with concurrent half-fluence crosslinking (PRK Xtra) was performed in eyes with borderline suspicious tomography (not amounting to forme fruste keratoconus) or low pachymetry between 450 and 474 µm with an otherwise unremarkable corneal tomography. Eyes with normal corneal tomography and thickness between 475 and 500 µm underwent standard PRK. The minimum follow-up period was 1 year.ResultsIn total, 109 eyes underwent PRK Xtra (Group A) and 118 eyes underwent PRK alone (Group B). The preoperative MRSE was −3.64 D and −3.38 D in Groups A and B, respectively (P=0.28). Group A had a significantly higher number of eyes with thinner corneas (P<0.01) and corneal tomographic abnormalities (P=0.02). At 1 year follow-up, 96.3% of eyes in group A as against 99.1% of eyes in group B achieved a best corrected distance visual acuity (CDVA) of 20/20 or better. No iatrogenic ectasia or hyperopic shift secondary to progressive flattening was noted in the PRK Xtra group. No significant difference in incidence of haze was noted.ConclusionPRK Xtra showed comparable safety, efficacy, and stability to PRK in eyes with thinner pachymetry and tomographic abnormalities. Combining crosslinking with PRK in suspicious tomographies augurs for safe and predictable outcomes.

Aspheric versus wavefront-guided aspheric photorefractive keratectomy in eyes with significant astigmatism

To compare the refractive and higher-order aberrations (HOAs) outcomes after photorefractive keratectomy (PRK) in patients with significant astigmatism using aspheric versus wavefront-guided aspheric profiles. Ophthalmic Research Center and Department of Ophthalmology, Shahid Beheshti University of Medical Sciences, Negah Eye Hospital, Tehran, Iran. Prospective randomized case series. One eye of each patient with a refractive astigmatism more than 2.00 diopters (D) randomly received aspheric PRK. In theother eye, wavefront-guided and aspheric treatment was performed using a personalized treatment advanced algorithm. Visual acuity, refractive errors, and HOAs were compared between the 2 groups preoperatively and 12months postoperatively. The study comprised 32 patients (64 eyes). The mean preoperative refractive astigmatism was -4.07 D ± 1.64 (SD) and -4.02±1.55 D in the aspheric group and wavefront-guided aspheric group, respectively (P=.2). The mean postoperative astigmatism was -0.46±0.37 D and -0.82±0.53 D in theaspheric group and wavefront-guided aspheric group, respectively (P=.02). Postoperatively, the root mean square of total HOAs was significantly increased in both groups. However, compared with wavefront-guided aspheric PRK, aspheric PRK induced fewer HOAs (P=.003). In eyes with high astigmatism, post-PRK residual astigmatism was lower in the aspheric group than in the wavefront-guided aspheric group. The increase in HOAs was significantly higher in the wavefront-guided aspheric group than in the aspheric group.

Myopic Surface Ablation in Asymmetrical Topographies: Refractive Results and Theoretical Corneal Elastic Response

To evaluate refractive results and the theoretical elastic response of photorefractive keratectomy in eyes with asymmetrical corneal surface and to compare such outcomes with a control-matched group of normal topographies. Retrospective interventional case series with matched comparison group. Thirty eyes with superior-inferior dioptric difference (SI index) > 1.40 diopter (D) were compared to 30 eyes with normal topographies. Bothgroups were matched for age, preoperative spherical equivalent (SE), mean keratometry, and percentage of tissue altered (PTA). Refractive results and the theoretical elastic modulus calculations were evaluated. The mean preoperative SI index in the asymmetrical group was 2.06 ± 0.56 D vs 0.14 ± 0.73 D in the control group (P < .001). From 3 to 12months postoperatively, the asymmetrical group presented a mean re-steepening of 0.51 ± 0.39 D vs 0.19 ± 0.40 D in the control group (P= .014). The mean PTA of14.42% generated a theoretical elastic modulus reduction of 10.25% in the asymmetrical group vs 2.45% in the control group (P= .006). The reduction of the theoretical elastic modulus correlated with thepreoperative SI index (ρ=-0.387, P= .007). After 36months, 90% of all eyes were within ±0.50D of SEand the theoretical elastic modulus did not presentasignificant difference between both groups(P= .085). Asymmetrical-topography corneas treated with myopic surface ablation presented an increased short-term keratometric re-steepening and reduction of the theoretical elastic moduli. The long-term follow-up indicated that, in selected cases of asymmetrical topographies, myopic surface ablation could induce a premature biomechanical elastic response ratherthan a progressive pathologic process.

Comparison of clinical outcomes between wavefront-optimized versus corneal wavefront-guided transepithelial photorefractive keratectomy for myopic astigmatism

To evaluate and compare the clinical outcomes, including visual acuity, refractive errors, and aberrations, between aberration-free transepithelial photorefractive keratectomy (PRK) and corneal wavefront-guided transepithelial PRK in eyes with myopic astigmatism. Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea. Retrospective comparative case series. Patients with myopic astigmatism were treated with aberration-free transepithelial PRK or corneal wavefront-guided transepithelial PRK using a 1050Hz high-repetition excimer laser.The safety, efficacy, predictability, and corneal aberrations were compared preoperatively and 1, 2, 3, and 6months postoperatively. The study comprised 188 patients (188 eyes); 91 eyes had aberration-free transepithelial PRK and 97 eyes corneal wavefront-guided transepithelial PRK. Six month after surgery, the mean uncorrected distance visual acuity was comparable (-0.06 logMAR±0.07 [SD] aberration-free group; -0.06±0.06 logMAR wavefront-guided group). The safety, efficacy, and predictability of refractive and visual outcomes were also comparable between groups. Corneal total root-mean-square (RMS) higher-order aberrations (HOAs) increased after treatment in both groups, although fewer RMS HOAs were induced in the corneal wavefront-guided group than in the aberration-free group. Spherical aberration increased similarly after treatment in both groups. However, coma and trefoil increased only in the aberration-free group. Aberration-free transepithelial PRK and corneal wavefront-guided transepithelial PRK were safe and effective for correction of myopic astigmatism without difference in visual acuity and refractive outcomes. However, the corneal wavefront-guided profile induced fewer corneal aberrations than the aberration-free profile.

Quality of vision after wavefront-guided laser in situ keratomileusis or photorefractive keratectomy: Contralateral eye evaluation

To compare quality of vision between laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California, USA. Prospective randomized case series. Patients had refractive surgery, with 1 eye treated with LASIKand the other with PRK. Eyes were randomized for dominance. The patients completed a questionnaire assessing quality of vision in each eye at the initial visit and 1, 3, 6, and 12months postoperatively. The study comprised 34 patients (68 eyes). There were no initial differences in quality of vision. The PRK eyes had worse clarity during the day (P=.001) and at night (P=.001), worse overall vision (P=.024), more vision fluctuation (P=.006), and more double vision (P=.022) at 1month. Eyes with higher preoperative higher-order aberrations (HOAs) having PRK had worse clarity during the day and at night (P=.006 and P=.012, respectively) and more vision fluctuation (P=.041); PRK eyes with lower preoperative HOAs had worse daytime clarity (P=.036) at 1month. After 1month, there were no differences. The quality of vision was better in LASIK eyes after 1month. At subsequent visits, there was no significant difference in quality of vision.

Outcomes and complications of excimer laser surgery in patients with collagen vascular and other immune-mediated inflammatory diseases

To assess refractive and visual outcomes and postoperative complications in a large number of patients with well-controlled collagen vascular and other immune-mediated inflammatory diseases. Optical Express, Glasgow, United Kingdom. Retrospective case series. The files were reviewed of patients who had collagen vascular and other immune-mediated inflammatory diseases and who had excimer laser surgery between 2008 and 2015. In all cases, the disease was well controlled with no flare or symptoms for a minimum of 6months preoperatively. The study comprised 622 patients (1224 eyes) with 1 of the following underlying diseases: rheumatoid arthritis (50.6% of patients), systemic lupus erythematosus (19.5%), psoriatic arthritis (10.5%), sarcoidosis (10.0%), ankylosing spondylitis (6.4%), multiple sclerosis (1.9%), or scleroderma (1.1%). Laser in situ keratomileusis (LASIK) was performed in 1114 eyes (91.0%) and photorefractive keratectomy (PRK) in 110 eyes (9.0%). The mean follow-up was 10.9months. The preoperative spherical equivalent ranged between -10.13 diopters (D) and +4.13 D (LASIK) and -9.50 D and +4.00 D (PRK). Postoperatively, 81.8% LASIK eyes and 82.3% PRK eyes were within ±0.50 D. The uncorrected distance visual acuity was 20/20 or better in 76.8% and 73.4%, respectively. Complications were mostly those that would be expected after excimer laser surgery in a population of patients without disease with the exception of 1 peripheral flap melt that responded to treatment with topical steroids. Excimer laser surgery can be safely performed in patients with well-controlled collagen vascular or other immune-mediated inflammatory disease. Dr. S.C. Schallhorn is a consultant to Abbott Medical Optics, Inc., Acufocus, Inc., and Carl Zeiss Meditec AG, and a global medical director for Optical Express. No other author has a financial or proprietary interest in any material or method mentioned.