Primary Photorefractive Keratectomy Research Articles

Repeat Versus Primary Photorefractive Keratectomy for Treatment of Myopia

Although effective, a portion of photorefractive keratectomy (PRK) patients will suffer residual myopia or relapse to myopic regression. This retrospective, non-randomized, comparative study, aimed to compare the efficacy of primary PRK versus PRK performed as retreatment after previous surgery for myopia. Data regarding the right eye of 220 consecutive myopic patients undergoing repeat or primary PRK in 2013–2017 were extracted. Groups were matched for demographics and preoperative spherical equivalent, sphere, astigmatism, uncorrected and corrected distance visual acuity (UDVA and CDVA). Primary outcomes were an efficacy index (ratio between the postoperative UDVA and the preoperative CDVA), a safety index (ratio between the postoperative and the preoperative CDVA), postoperative UDVA and CDVA, and deviation from target refraction. Primary PRK showed significant superiority in logMAR UDVA (0.01 ± 0.05 versus 0.05 ± 0.10, p = 0.001), logMAR CDVA (0.01 ± 0.05 versus 0.04 ± 0.08, p = 0.01), efficacy index (1.00 ± 0.05 versus 0.97 ± 0.09, p = 0.003) and safety index (1.00 ± 0.06 versus 0.98 ± 0.08, p = 0.04) compared to repeat PRK, but had a significantly higher share of patients with postoperative spherical equivalent (74.5% versus 67.3%) and cylinder (74.5% versus 68.2%) in the range of ±0.5 D. To conclude, enhancement PRK leads to inferior efficacy and safety with greater deviation from target refraction. Adjusted nomograms for repeat PRK may be warranted.

Femtosecond LASIK Retreatments After Primary Myopic Photorefractive Keratectomy.

The purpose of the study was to evaluate the results and complications of laser-assisted in situ keratomileusis (LASIK) using a femtosecond laser as a retreatment modality of myopia and myopic astigmatism after previous myopic photorefractive keratectomy (PRK). In this retrospective, consecutive, noncomparative case series study, 69 eyes of 41 patients receiving femtosecond LASIK after previous myopic PRK were evaluated. The mean age was 43.0 ± 8.9 years. The preoperative mean SE was -1.82 ± 1.01 diopter (D), range -0.62 to -6.25. The mean central epithelial thickness was 65 ± 5 μm. A flap was created using a low-energy femtosecond laser (Ziemer LDV Z8), with a programmed thickness calculated by adding 40 μm to the epithelial thickness. Refractive ablation was performed using a Technolas Teneo 317 laser (Bausch and Lomb). Twelve months after LASIK, the mean SE was -0.03 ± 0.17 D, with all eyes ≤0.50 D of SE. The mean DE was 0.30 ± 0.25, with 62 eyes (89.9%) ≤0.50 D and all eyes ≤1 D. The mean corrected distance visual acuity (CDVA) was 0.04 ± 0.10 logMAR; no eye lost more than 1 line of CDVA. The mean uncorrected distance visual acuity was 0.07 ± 0.13 logMAR, being 20/25 or better in all eyes. The safety index (postoperative CDVA/preoperative CDVA) was 1.05. The efficacy index (postoperative uncorrected distance visual acuity/preoperative CDVA) was 0.98. No significant complications occurred. Myopic retreatments by femtosecond LASIK after primary PRK yielded excellent refractive results without relevant complications. The flap thickness must be tailored to the epithelial thickening after PRK.

PRK Enhancement for Residual Refractive Error After Primary PRK: A Retrospective Study.

IntroductionThe efficacy and safety of photorefractive keratectomy (PRK) has been well documented, but outcomes of PRK enhancement following PRK remain understudied. This study aimed to evaluate the safety, efficacy, and predictability of PRK enhancement in patients with residual refractive error after primary PRK and compare these results to prior studies as well as Food and Drug Administration (FDA) safety and efficacy clinical endpoints.MethodsThis non-randomized, retrospective chart analysis included eyes with a history of PRK that underwent PRK enhancement at a single center. Post-enhancement data were documented at 3-month and 1-year visits. Patient characteristics between the study group and a control group who underwent primary PRK only were compared. Safety and efficacy measures included change in uncorrected distance visual acuity (UDVA), change in corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), amount of induced astigmatism, and presence of serious adverse events.ResultsA total of 188 eyes from 141 patients were included. When compared to the control group, women underwent PRK enhancement at a higher rate than men (P = 0.004). The group undergoing PRK enhancement had a higher sphere (P = 0.013) and spherical equivalent (P = 0.004) than the control group at the time of primary PRK. MRSE was reduced to − 0.97 ± 0.72 D (− 2.25 to + 2.13 D) from pre-enhancement values of − 0.98 ± 0.66 D (− 2.75 to + 1.75 D) and stable over 12-month visits with 86% and 98% of eyes within ± 0.50 D and ± 1.00 D of target, respectively. UDVA of 20/20 or better was achieved in 75% of eyes. The UDVA of 75% of eyes remained the same or improved by 1 or more Snellen lines compared with pre-enhancement CDVA.ConclusionOur results demonstrate that, when compared with previous studies, modern PRK enhancement after PRK has improved visual acuity and refractive outcomes. Though PRK enhancement is not an FDA approved procedure, we show that it meets or exceeds the FDA criteria for the correction of refractive error.

Predictors of myopic photorefractive keratectomy retreatment

To determine the factors associated with retreatment after photorefractive keratectomy (PRK) in myopic eyes. Care-Vision Laser Centers, Tel-Aviv, Israel. Retrospective cohort study. A large database on myopic PRK with mitomycin-C (MMC) performed from 2005 to 2012 was studied. Patients were divided into 2 groups according to whether they had retreatment. Multiple preoperative and intraoperative parameters were analyzed for association with retreatment. A total of 9699 eyes of 9699 consecutive patients were studied. The mean age was 25.9years±7.3 (SD); 54.1% were men. The mean preoperative subjective spherical equivalent and astigmatism were -4.30±2.18 diopters (D) (range -0.5 to -13.0 D) and 0.77±0.83 D (range 0 to 6.0 D), respectively. Twohundred twenty-three eyes (2.30%) were retreated. The 2-year retreatment rate decreased from 42 (6.17%) for primary PRK treatments done in 2005 to 2 (0.10%) for primary PRK done in 2012 (R2=0.79, P<.001). Multiple binary logistic regression analysis showed that transepithelial PRK, astigmatism equal to or higher than 3.5 D, and surgeon factor significantly increased theodds of retreatment. Additional parameters significant on univariate analysis alone included age older than 40years, low preoperative sphere, maximum ablation depth less than 45μm, preoperative corrected distance visual acuity better than 20/20, MMC application longer than 40seconds, and optical ablation zone smaller than 7.0mm. The retreatment incidence of PRK has continued to decrease. High astigmatism and transepithelial PRK were associated with increased myopic PRK retreatment rates.

A retrospective analysis of the postoperative use of loteprednol etabonate gel 0.5% following laser-assisted in situ keratomileusis or photorefractive keratectomy surgery.

BackgroundWhile loteprednol etabonate ophthalmic gel 0.5% (LE gel) is approved for treatment of postoperative ocular inflammation and pain, there have been no reported studies in patients undergoing laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK).MethodsThis was a retrospective chart review conducted at five refractive surgical centers in the USA. Data were collected from primary LASIK or PRK surgery cases in which LE gel was used postoperatively as the clinician’s routine standard of care and in which patients were followed-up for up to 6 months. Data extracted from charts included patient demographics, surgical details, LE gel dosing regimen, pre- and postsurgical refractive characteristics, intraocular pressure (IOP) measurements, and visual acuity. Primary outcomes included postoperative IOP elevations, adverse events, and early discontinuations.ResultsData were collected on 189 LASIK eyes (96 patients) and 209 PRK eyes (108 patients). Mean (standard deviation [SD]) years of age at surgery was 36.0 (11.7) and 33.9 (11.3) in LASIK and PRK patients. LE gel was prescribed most often four times daily during the first postoperative week, regardless of procedure; the most common treatment duration was 7–14 days in LASIK and ≥30 days in PRK patients. No unusual corneal findings or healing abnormalities were reported. Mean postoperative uncorrected distance visual acuity was 20/24 in LASIK and 20/30 in PRK eyes. Mild/trace corneal haze was reported in 20% of PRK patients; two PRK patients with moderate/severe corneal haze were switched to another corticosteroid. Mean postoperative IOP did not increase over time in either LASIK or PRK eyes (P≥0.331); clinically significant elevations from baseline in IOP (≥10 mmHg) were noted in only three eyes of two PRK patients.ConclusionLE gel appears to have a high level of safety and tolerability when used for the management of postoperative pain and inflammation following LASIK and PRK surgery.

Mitomycin C application in refractive surgery

Over the years, mitomycin C has been used by refractive surgeons to prophylactically decrease haze after surface ablation procedures and therapeutically in the treatment of preexisting haze. Development of mitomycin C treatments has had a significant role in the revival of surface ablation techniques. We reviewed the literature regarding mechanism of action of mitomycin C, its role in modulating wound healing after refractive surgery, and its safety and efficacy as adjuvant therapy applied after primary photorefractive keratectomy surgery or after photorefractive keratectomy re-treatment after laser in situ keratomileusis and other corneal surgeries and disorders. The drug is a potent mitotic inhibitor that effectively blocks keratocyte activation, proliferation, and myofibroblast differentiation. Many studies have suggested that mitomycin C is safe and effective in doses used by anterior surface surgeons, although there continue to be concerns regarding long-term safety. After initial depletion of anterior keratocytes, keratocyte density seems to return to normal 6 to12 months after the use of mitomycin C when corneas are examined with the confocal microscope. Most clinical studies found no difference between preoperative and postoperative corneal endothelial cell densities when mitomycin C 0.02% was applied during refractive surgery,with exposure time of 2 minutes or less. After approximately 14 years of use, mitomycin C has been found to be effective when used for prevention and treatment of corneal haze.

Factors that Influence Intraocular Pressure Changes after Myopic and Hyperopic LASIK and Photorefractive Keratectomy: A Large Population Study

To describe the factors that influence the measured intraocular pressure (IOP) change and to develop a predictive model after myopic and hyperopic LASIK and photorefractive keratectomy (PRK) in a large population. Retrospective, observational case series. Patients undergoing primary PRK or LASIK with a refractive target of emmetropia between January 1, 2008, and October 5, 2011. The Optical Express database was queried for all subjects. Data were extracted on procedure specifics, preoperative central corneal thickness (CCT), IOP (using noncontact tonometry), manifest refraction, average keratometry, age, gender, and postoperative IOP at 1 week, 1 month, and 3 months. A linear mixed methods model was used for data analysis. Change in IOP from preoperatively to 1 month postoperatively. A total of 174 666 eyes of 91 204 patients were analyzed. Hyperopic corrections experienced a smaller IOP decrease than myopic corrections for both PRK and LASIK (P<0.0001). Patients who underwent LASIK had a 0.94 mmHg (95% confidence interval [CI], 0.89-0.98) greater IOP decrease than patients who underwent PRK (P<0.0001), reflecting the effect of the lamellar flap. The decrease in IOP was linearly related to preoperative manifest spherical equivalent (MSE) for myopic PRK and LASIK (P<0.0001), weakly correlated with preoperative MSE after hyperopic LASIK, and not related to preoperative MSE after hyperopic PRK. The single greatest predictor of IOP change was preoperative IOP across all corrections. By using the available data, a model was constructed to predict postoperative IOP change at 1 month; this was able to explain 42% of the IOP change after myopic LASIK, 34% of the change after myopic PRK, 25% of the change after hyperopic LASIK, and 16% of the change after hyperopic PRK. Myopic procedures lower measured IOP more than hyperopic procedures; this decrease was proportional to the amount of refractive error corrected. Independent of the refractive correction, the creation of the lamellar LASIK flap decreased measured IOP by 0.94 mmHg. A best-fit model for IOP change was developed that may allow better interpretation of post-laser vision correction IOP values.

Mitomycin C: Biological Effects and Use in Refractive Surgery

To provide an overview of the safety and efficacy of mitomycin C (MMC) as adjuvant therapy after refractive surgery procedures. Literature review. Over the past 10 years, MMC has been used by refractive surgeons to prophylactically decrease haze after surface ablation procedures and therapeutically in the treatment of preexisting haze. Development of MMC treatments has had a significant role in the revival of surface ablation techniques. We reviewed the literature regarding mechanism of action of MMC, its role in modulating wound healing after refractive surgery, and its safety and efficacy as adjuvant therapy applied after primary photorefractive keratectomy surgery or after photorefractive keratectomy re-treatment after laser in situ keratomileusis and other corneal surgeries and disorders. The drug is a potent mitotic inhibitor that effectively blocks keratocyte activation, proliferation, and myofibroblast differentiation. Many studies have suggested that MMC is safe and effective in doses used by anterior surface surgeons, although there continue to be concerns regarding long-term safety. After initial depletion of anterior keratocytes, keratocyte density seems to return to normal 6 to 12 months after the use of MMC when corneas are examined with the confocal microscope. Most clinical studies found no difference between preoperative and postoperative corneal endothelial cell densities when MMC 0.02% was applied during refractive surgery, with exposure time of 2 minutes or less. After more than 10 years of use, MMC has been found to be effective when used for prevention and treatment of corneal haze. Questions remain regarding optimal treatment parameters and long-term safety.

Mitomycin C in Photorefractive Keratectomy

To evaluate the outcome of primary or retreatment photorefractive keratectomy (PRK) or phototherapeutic keratectomy (PTK) with mitomycin C (MMC) 0.02% applied prophylactically intraoperatively for the prevention of haze and regression in cases of significant haze and regression after primary PRK, due to previous radial keratotomy (RK), in primary PRK eyes with high myopia, and in comeas with a previous superficial foreign body scar. This was a retrospective evaluation of 34 eyes treated with PRK or PTK and intraoperative MMC. Mitomycin C was applied immediately after laser ablation. Postoperative examinations were conducted 3 and 7 days after surgery and monthly for 6 months. Haze was graded on a standard 0+ (clear cornea) to 4+ (total opacity) scale. Visual acuity was measured as a general baseline indicator. Postoperatively, uncorrected visual acuity (UCVA) was 20/20 or better in 21 eyes and 20/25 in 5 eyes with best spectacle-corrected visual acuity (BSCVA) of 20/20 or better. Three eyes achieved UCVA of 20/30 with BSCVA of 20/20 or better; and 5 eyes had UCVA of 20/40 with BSCVA of 20/20 or better. Nineteen (56%) eyes had grade 0+ haze and 15 (44%) eyes had grade 0.5+ haze (trace haze) at 6-month follow-up. Mitomycin C 0.02% used prophylactically during PRK or PTK retreatment was effective in preventing significant recurrent haze from developing. In eyes with high myopia or previous RK or scarring, MMC was effective in preventing significant haze formation.

Photorefractive Keratectomy With 0.02% Mitomycin C for Treatment of Residual Refractive Errors After LASIK

To evaluate the efficacy and safety of prophylactic mitomycin C (MMC) during photorefractive keratectomy (PRK) over LASIK flaps for the treatment of residual refractive errors following LASIK. In this single center, retrospective clinical study, 30 eyes of 33 patients (mean age 37.2 years) who had MMC (0.02%, 30 to 120 seconds) during PRK for the treatment of residual refractive errors following myopic LASIK were evaluated. The retreatment procedures were performed with a VISX S4 laser with iris registration. All patients underwent slit-lamp microscopy, manifest and cycloplegic refraction, corneal topography, pachymetry, pupillometry, and wavefront analysis pre- and postoperatively. All patients underwent follow-up at 1 day, 1 week, and 1, 3, and 6 months and thereafter as required. Mean time between LASIK and PRK retreatment was 67.3 months (range: 7 to 113 months). No intra- or postoperative complications occurred during primary LASIK or PRK retreatment. Mean spherical equivalent refraction of attempted correction with PRK was -0.94 diopters (D) (range: -2.38 to +0.75 D). At mean 7.1-month follow-up, the average uncorrected visual acuity (UCVA) improved from 20/50 (range: 20/30 to 20/200) to 20/28 (range: 20/15 to 20/70). Twenty-seven of 30 eyes showed improvement in UCVA. Two eyes had subjective improvement of glare symptoms (and objective improvement in higher order aberrations), and one eye lost one line of best spectacle-corrected visual acuity due to unrelated corneal abrasion in the postoperative period. None of the eyes in the cohort developed postoperative haze. Photorefractive keratectomy with prophylactic MMC (0.02%) is a safe and effective option for treating myopic regression following LASIK. A single intraoperative application of 0.02% MMC for as few as 30 seconds was effective in preventing postoperative haze formation.

Corneal Haze Following PRK With Mitomycin C as a Retreatment Versus Prophylactic Use in the Contralateral Eye

To report photorefractive keratectomy (PRK) treated with mitomycin C (MMC) for previous corneal haze in one eye and PRK with MMC to prevent corneal haze formation in the fellow eye. A 40-year-old woman underwent PRK with MMC to treat previous corneal haze (secondary to previous PRK without MMC) for residual refractive error of +0.50 +0.25 x 165 in the left eye and PRK with MMC to prevent corneal haze in the right eye. Postoperative slit-lamp examination revealed no haze in the right eye, but continued mild haze in the left eye. Treatment with PRK and MMC for previous corneal haze is not as effective as primary PRK with MMC in preventing postoperative corneal haze formation.

Enhancement outcomes after photorefractive keratectomy and laser in situ keratomileusis using topographically guided excimer laser photoablation

To evaluate the efficacy and safety of topographically guided excimer laser photoablation to retreat unsuccessful myopic and hyperopic photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Eye Clinic, San Salvatore Hospital, University of L'Aquila, L'Aquila, Italy. At least 3 months after primary PRK (Group A) or primary LASIK (Group B), 48 eyes of 42 patients were submitted to PRK or LASIK enhancements. The eyes were treated with an excimer laser linked to a computerized videokeratography unit with a topographically supported customized ablation workstation. The mean follow-up was 27.8 months +/- 8.2 (SD). In Group A, the uncorrected visual acuity (UCVA) changed from 0.5 +/- 0.7 logarithm of the minimum angle of resolution (logMAR) (range 20/600 to 20/200) to 0.1 +/- 0.7 logMAR (range 20/60 to 20/20); the mean best spectacle-corrected visual acuity (BSCVA) changed from 0.1 +/- 0.7 logMAR (range 20/50 to 20/20) to 0 +/- 0.7 logMAR (range 20/50 to 20/20) after the enhancement. In Group B, the UCVA changed from 0.7 +/- 0.8 logMAR (range 20/600 to 20/40) to 0.1 +/- 0.7 logMAR (range 20/40 to 20/20); the mean BSCVA improved from 0.2 +/- 0.8 logMAR (range 20/30 to 20/20) to 0 +/- 1.3 logMAR (range 20/25 to 20/20) after surgery. The enhancements using topographically guided excimer laser photoablation with a topographically supported customized ablation method resulted in satisfactory and stable visual outcome with good safety and efficacy after unsuccessful PRK and LASIK.

Laser in situ keratomileusis for residual myopia after photorefractive keratectomy

Purpose: To evaluate the efficacy and safety of laser in situ keratomileusis (LASIK) for myopic regression and undercorrection after photorefractive keratectomy (PRK).Setting: The Eye Institute, Sydney, Australia.Methods: Fifty eyes of 32 patients were treated by LASIK for residual myopia following primary PRK. The mean spherical equivalent refraction (SEQ) was −2.92 diopters (D) ± 1.57 (SD) (range −0.75 to −7.88 D). The mean refractive cylinder was 0.96 ± 0.74 D (range 0 to 3.50 D). For analysis, the eyes were divided into 2 groups: those with 0 or low corneal haze (Group 1) and those with severe corneal haze (Group 2). In Group 1, the SEQ was −1.99 ± 0.79 D (range −0.75 to −3.75 D) and in Group 2, −3.77 ± 1.62 D (range −0.75 to −7.90 D). The procedure was performed using the Chiron Automated Corneal Shaper® and the Summit Apex Plus® laser. The mean interval between PRK and LASIK was 25 months (range 9 to 59 months). The following parameters were studied before and after LASIK retreatment: SEQ, mean refractive cylinder, uncorrected visual acuity (UCVA), and best corrected visual acuity (BCVA). Complications after LASIK retreatment were evaluated.Results: Six months after LASIK, the mean SEQ in all eyes was −0.65 ± 0.86 D (range +1.50 to −3.35 D); 70.0% of eyes were within ±1.00 D of emmetropia and the UCVA was 6/12 or better in 72.5%. The mean SEQ in Group 1 was −0.22 ± 0.55 D (range −0.88 to −1.50 D) and in Group 2, −0.97± 0.92 D (range 0.12 to −3.25 D); the UCVA was 6/12 or better in 94.0% of eyes in Group 1 and in 56.0% in Group 2. No statistically significant between-group difference was found in lines of Snellen acuity lost or gained at 6 months. No eye lost more than 1 line of BCVA.Conclusions: Laser in situ keratomileusis appears to be a safe, effective, and predictable procedure for treating eyes with 0 or low haze with residual myopia after PRK. It is less predictable in eyes with severe haze.

Laser in situ keratomileusis for treatment of residual myopia after photorefractive keratectomy

PURPOSE: To evaluate the results of laser in situ keratomileusis after photorefractive keratectomy. METHODS: Eighty eyes of 80 patients with residual myopia after photorefractive keratectomy were reoperated with laser in situ keratomileusis. The study was retrospective. Laser in situ keratomileusis was performed using the automated corneal shaper microkeratome and Chiron Technolas 217-C d1 excimer laser. Data measured after laser in situ keratomileusis included uncorrected visual acuity, best-corrected visual acuity, refraction, haze, pachymetry, and keratometry. The follow-up was at least 12 ± 1.6 months (range, 12 to 15 months). RESULTS: After laser in situ keratomileusis the mean spherical equivalent was −0.24 diopters ± 0.78. (range, −3 to +1.5) at 12 months, and the mean uncorrected visual acuity was 0.76 diopters ± 0.24 (range, 0.1 to 1). Sixty-five eyes (81.3%) had various degrees of haze after laser in situ keratomileusis. One eye (1.2%) lost 2 lines of best-corrected visual acuity. CONCLUSIONS: Laser in situ keratomileusis enhancement may be a good alternative to correct residual myopia and astigmatism after primary photorefractive keratectomy. Corneal haze is a common problem in these eyes, and the treatment after laser in situ keratomileusis enhancement should be the same as the treatment after primary photorefractive keratectomy.

Laser in situ keratomileusis enhancement after photorefractive keratectomy.

To describe the safety, effectiveness, and predictability of laser in situ keratomileusis (LASIK) for correcting residual myopia after primary photorefractive keratectomy (PRK). A retrospective, noncomparative case series. Thirty-six consecutive eyes of 30 patients underwent LASIK after primary PRK. A Multiscan Schwind excimer laser was used for LASIK enhancement. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity, refraction, videokeratography, and complications were determined before and after LASIK retreatment. Follow-up was at least 12 months. Before LASIK, 11.11% of eyes showed a UCVA of 20/40 or better. This increased to 94.44% 12 months after LASIK. A UCVA of 20/25 or better was achieved in 0% before and in 72.22% after retreatment. Refraction +/-0.5 diopters (spherical equivalent) represented 0% of eyes before and 77.78% of eyes after enhancement. Before LASIK, two eyes had significant haze. Haze remained in these two eyes and appeared in another eye. Laser in situ keratomileusis proved to be safe and effective for treating residual myopia after PRK. Care must be taken when considering LASIK retreatment in patients with significant haze after primary PRK.

Symptoms of dry eye and recurrent erosion syndrome after refractive surgery

Purpose To determine the incidence and severity of patient complaints typical of dry eye and recurrent erosion syndrome after excimer laser refractive surgery and to compare the incidence of these symptoms after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Setting Outpatient university practice. Methods A questionnaire was mailed to 1731 patients who had had primary myopic PRK or LASIK at least 6 months previously. Questions were designed to determine the incidence and character of ocular dryness and recurrent erosion symptoms and their impact on patient satisfaction and willingness to have surgery again. Responses from PRK and LASIK patients were compared. Results Responses from 231 PRK patients and 550 LASIK patients revealed an incidence of dryness symptoms in 43% and 48%, respectively ( P > .05). Soreness of the eye to touch was reported by 26.8% and 6.7%, respectively ( P < .0001). Sharp pains occurred in 20.4% of PRK patients and 8.0% of LASIK patients ( P = .0001). Complaints of the eyelid sticking to the eyeball occurred in 14.7% and 5.6%, respectively ( P = .0001). All symptoms occurred predominantly on waking. Frequency of eyelid sticking ( P < .0005) and sharp pain ( P < .005) symptoms, as well as severity of sharp pain symptoms ( P < .0001), were significantly greater in PRK patients than in LASIK patients. On a scale of 0 to 10 (10 high), median overall patient satisfaction with surgery was 9 in both groups. Soreness of the eyelid to touch occurred significantly more frequently among patients with symptoms of sharp pains on waking ( P < .001) and the sensation of the eyelid sticking to the eyeball ( P < .001). Patients with 1 or more symptoms were twice as likely as asymptomatic patients to have a satisfaction score of less than 8 ( P < .001). Conclusions Ocular dryness symptoms occurred commonly after PRK and LASIK. Symptoms suggestive of mild recurrent erosions included sharp pains, the sensation of the eyelid sticking to the eyeball, and soreness of the eyelid to touch, a previously unrecognized symptom of this condition. These symptoms occurred commonly after excimer laser procedures but were significantly more common, more severe, and more prolonged after PRK. The presence of these symptoms had a significant effect on patient satisfaction.

Apical nodular subepithelial corneal scar after retreatment in hyperopic photorefractive keratectomy

PurposeTo report a complication, apical nodular subepithelial corneal scar, that can occur after hyperopic photorefractive keratectomy (PRK) retreatment. SettingIstanbul University Eye Research Center, Istanbul, Turkey. MethodsTwelve eyes of 6 patients with apical nodular subepithelial corneal scar were retrospectively studied. Mean age of the 5 men and 1 woman was 30.2 years ± 5.4 (SD). All eyes had hyperopic PRK retreatment for regression 9.5 ± 1.44 months after primary hyperopic PRK. Mean spherical equivalent refraction of the residual hyperopia before retreatment was +4.67 ± 0.81 diopters (D). All patients had a corneal haze grade of less than 1+. Hyperopic PRK retreatment was performed with a 193 nm excimer laser (Chiron Technolas Keracor 116). ResultsApical nodular subepithelial corneal scars developed within the first month of hyperopic PRK retreatment and progressed until the third month in 12 eyes of 6 patients. The lesion was round and symmetrical in both eyes, smaller than 2.0 mm, and centrally located. During the mean 40.66 ± 2.46 month follow-up, the lesion did not change in size or density. Mean spherical equivalent refraction after retreatment was 2.88 ± 0.88 D (range +1.50 to +4.00 D) at 1 month and +4.36 ± 1.83 D at last follow-up. Refraction was unmeasurable in 3 eyes. Five eyes lost 1 line of best spectacle-corrected visual acuity and 7 eyes, 2 or more lines. The surface regularity indexes were higher than 2.00 in all the eyes. ConclusionHyperopic PRK retreatment may cause the sight-threatening complication of apical nodular subepithelial corneal scar. This complication behaves unlike corneal haze and does not resolve spontaneously over time.

Epithelial scrape for photorefractive keratectomy overcorrection associated with induced regression.

To study the effect of combined corneal epithelial scrape and contact lens wear treatment on regression in eyes with symptomatic overcorrection after photorefractive keratectomy (PRK) or PRK retreatment. Fifteen eyes had corneal epithelial scrape with a scalpel followed by soft contact lens wear for approximately 1 month. Eight of the eyes were treated 3-4 months after the laser procedure, and seven eyes were treated >4 months after laser treatment. Fifteen eyes that had the same level of PRK correction and monitored during the same interval after PRK were used as matched control eyes. Epithelial scrape was performed for mean spherical equivalent (SE) of +1.1+/-0.4 diopters (D) (range, +0.50 to +1.75 D) at mean 6.1+/-3.2 months after PRK or PRK retreatment. The SE in these eyes was +0.5+/-0.6 D (range, -0.25 to +1.25 D) 3 months after epithelial scrape and +0.4+/-0.5 D (range, -0.75 to +1.25 D) 6 months after scrape. The change in scraped eyes at 3 and 6 months compared to before scrape was statistically significant (p = 0.001 and p = 0.001, respectively). The change in mean SE at 6 months after scrape (-0.7+/-0.5 D) was significantly different than the change noted in matched control eyes that were not scraped (-0.1+/-0.2 D) over the same interval after the PRK or PRK retreatment procedure. The change in SE at 6 months after epithelial scrape was greater for the eyes scraped 4 months or less (mean, 3.6+/-0.5 months) after PRK (-0.9+/-0.3 D) than eyes scraped >4 months (9.0+/-2.6 months) after PRK (-0.4+/-0.5 D). This difference approached statistical significance (p = 0.06). Epithelial scrape and soft contact lens treatment for symptomatic overcorrection after PRK may induce regression and is more likely to be effective when performed <4 months after the primary PRK or PRK retreatment procedure.

Diametral ablation--a technique to manage decentered photorefractive keratectomy for myopia.

Decentered ablation after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) is an intraoperative complication that may significantly influence the visual outcome. Currently, there is no accepted technique available to manage this problem. A technique of reoperation for eccentric ablation after PRK called diametral ablation is presented that uses a transepithelial phototherapeutic keratectomy (PTK) that leaves epithelium over the area of primary PRK. This residual epithelium acts as a shield for the previously treated stroma during a second PRK located opposite to the primary PRK with reference to the pupil center. The results of six such retreatments (6 eyes of 6 patients) are presented. In all eyes, a significant improvement regarding centration and subjective complaints was achieved. The eccentricity was reduced from 1.43+/-0.66 mm to 0.36+/-0.15 mm (P = .003). Diametral ablation is a promising alternative treatment of eccentric ablation.

Epithelial removal with the excimer laser (laser-scrape) in photorefractive keratectomy retreatment

Objectives To retrospectively evaluate refractive and topographic outcomes after excimer laser photorefractive keratectomy (PRK) retreatment using the laser-scrape technique for epithelial removal. Design Retrospective clinical study. Participants Thirty eyes of patients who had PRK retreatment for undercorrection after primary PRK were examined. Intervention The PRK retreatment was performed using a laser-scrape technique in which the excimer laser was used to remove the majority of the epithelium overlying the anterior stromal surface before additional PRK ablation. Main outcome measures Uncorrected visual acuity, best-corrected visual acuity (BCVA), surface regularity index (SRI), and surface asymmetry index were measured. Results Primary PRK was performed for myopia of −5.1 ± 1.7 diopters (range, −1.1 to −7.5 diopters). Mean spherical equivalent (SE) was −1.3 ± 0.4 diopters (range, −0.6 to −2.0 diopters) before retreatment. Mean SE 6 months after retreatment decreased to +0.1 ± 0.4 diopter (range, +1.25 to −0.75 diopters; P < 0.0001). Four eyes (15%) were more than +0.5 diopter overcorrected at 6 months. Ninety-six percent of eyes achieved mean SE within ±1 diopter and 77% within ±0.5 diopter of emmetropia after retreatment. Visual acuity improved significantly 6 months after reablation ( P < 0.0001) with 100% 20/40 or better and 73% 20/25 or better without correction. Final BCVA also improved compared with before retreatment ( P = 0.02). Twelve eyes gained 1 line of BCVA and no eye lost more than 1 line of BCVA. The SRI before retreatment was 0.6 ± 0.3 (range, 0.0–0.9) and remained the same 0.6 ± 0.2 (range, 0.1–1.0; P = 0.8), 6 months after retreatment. Conclusion Excimer laser PRK retreatment using the laser-scrape technique for epithelial removal is an accurate and safe procedure for treating undercorrection of eyes after PRK for low-to-moderate myopia.