Complications of photorefractive keratectomy for myopia: two year follow-up of 3000 cases

Efficacy and safety of single-step transepithelial photorefractive keratectomy with the all-surface laser ablation SCHWIND platform without mitomycin-C for high myopia: A retrospective study of 69 eyes

BACKGROUND

Studies suggest that transepithelial photorefractive keratectomy (TransPRK) with the all-surface laser ablation (ASLA)-SCHWIND platform is effective and safe for both low-moderate myopia and high myopia. In most studies, mitomycin-C is administered immediately after surgery to prevent corneal opacification (haze), which is a significant complication of photorefractive keratectomy in general. However, there is evidence that adjuvant mitomycin-C induces endothelial cytotoxicity. Moreover, a recent study showed that omitting adjuvant mitomycin-C did not increase haze in low-moderate myopia. The present case-series study examined the efficacy, safety, and haze rates of eyes with high myopia that underwent ASLA-SCHWIND TransPRK without adjuvant mitomycin-C.

METHODS

All consecutive eyes with high myopia (≤-6 D) that were treated in 2018-2020 with the SCHWIND Amaris 500E® TransPRK excimer laser without adjuvant mitomycin-C in a tertiary-care hospital (France) and were followed up for 6 months were identified. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and spherical equivalent (SE) were recorded before and after surgery. Postoperative haze was graded using the 4-grade Fantes scale. Efficacy rate (frequency of eyes with 6-month UCVA ≤0.1 logMAR), safety rate (frequency of eyes that lost <2 BSCVA lines), predictability (frequency of eyes with 6-month SE equal to target SE±0.5 D), efficacy index (mean UCVA at 6 months/preoperative BSCVA), and safety index (BSCVA at 6 months/preoperative BSCVA) were computed.

RESULTS

Sixty-nine eyes (38 patients) were included. Mean preoperative and 6-month SE were -7.44 and -0.05 D, respectively. Mean 6-month UCVA and BSCVA were 0.00 and -0.02 logMAR, respectively. Efficacy rate and index were 95.7% and 1.08, respectively. Safety rate and index were 95.7% and 1.13, respectively. Predictability was 85.5%. Grade 3-4 haze never arose. At 6 months, the haze rate was zero.

CONCLUSIONS

ASLA-SCHWIND TransPRK without mitomycin-C appears to be safe as well as effective and accurate for high myopia.

Persistent epithelial defect after photorefractive keratectomy in a patient with autism

Refractive surgery has been performed under general anesthesia on pediatric and neurobehaviorally challenged adults without reported loss of vision or serious complications. Persistent epithelial defect (PED) is a rare complication of photorefractive keratectomy (PRK) in the general refractive surgery population. We report a case of PED following PRK under general anesthesia for high myopia in a man with autism and ocular history of juvenile open-angle glaucoma and dry eye syndrome.

Femtosecond laser assisted in situ keratomileusis (FS-LASIK) yields better results than transepithelial photorefractive keratectomy (Trans-PRK) for correction of low to moderate grade myopia

INTRODUCTION

The purpose of this study was to compare the outcomes of transepithelial photorefractive keratectomy (Trans-PRK) with femtosecond laser assisted in situ keratomileusis (FS-LASIK) for the correction of low to moderate myopia.

METHODS

A retrospective cohort study design was used. The study group included patients with myopia less than -6.0 D, with or without concomitant astigmatism under 2.0 D, who were treated with FS-LASIK or Trans-PRK in 2013 through 2014. Background, clinical and outcome data were collected from the patient files. A comparison between eyes treated with FS-LASIK or Trans-PRK was performed.

RESULTS

The Trans-PRK group was comprised of 1793 eyes and the FS-LASIK group of 666 eyes. Mean ± SD spherical equivalent (SE) refraction prior to surgery was -3.43 ± 1.27 D in the Trans-PRK group and -3.18 ± 1.34 D in the FS-LASIK group (p < 0.001). Efficacy index values were 0.95 ± 0.14 in the Trans-PRK group and 0.98 ± 0.12 in the FS-LASIK group (p < 0.001), and corresponding safety index values were 0.96 ± 0.13 and 0.99 ± 0.12 (p < 0.001). Distance from target refraction was 0.45 ± 0.42 D in Trans-PRK group and 0.43 ± 0.38 D in the FS-LASIK group (p = 0.537); 71.6% and 74.2% of eyes were within ±0.5 D of attempted correction, respectively (p = 0.193).

CONCLUSIONS

Both Trans-PRK and FS-LASIK demonstrated excellent results, mostly comparable with the current literature. FS-LASIK achieved better results than Trans-PRK surgery in the efficacy and safety parameters.

Comparison of clinical results between trans-PRK and femtosecond LASIK for correction of high myopia

Background

To compare the clinical outcomes of transepithelial photorefractive keratectomy (TPRK) with femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for correction of high myopia.

Methods

In this prospective, non-randomised, cohort study, 85 eyes of 46 patients treated with TPRK and 80 eyes of 42 patients treated with FS-LASIK were included. All eyes were highly myopic (spherical equivalent refraction <− 6.00 diopters). Both TPRK and FS-LASIK were performed by Schwind Amaris 750S excimer laser. Visual acuity, refraction, corneal high order aberration (HOA) and other variables were analyzed before and at 1, 3, 6, 12 months after surgery.

Results

At 12 months after surgery, uncorrected logMAR distance visual acuity (UDVA) in the TPRK and FS-LASIK groups was − 0.04 ± 0.04 and − 0.01 ± 0.08, respectively (P = 0.039). Corrected logMAR distance visual acuity (CDVA) was − 0.06 ± 0.05 and − 0.04 ± 0.05 in both groups (P = 0.621). For UDVA, 86% of eyes in the TPRK group and 80% in the FS-LASIK group remained unchanged or improved one or more logMAR lines (P = 0.314), compared to preoperative CDVA. For CDVA, 97% of eyes in the TPRK group and 90% in the FS-LASIK group remained unchanged or improved one or more lines (P = 0.096), compared to preoperative CDVA. Spherical equivalent refraction was − 0.05 ± 0.39 and − 0.26 ± 0.47 in both groups (P = 0.030). 87% of eyes in the TPRK group and 73% in the FS-LASIK group achieved ±0.50 D target refraction (P = 0.019). All 85 eyes (100%) in the TPRK group and 75 eyes (92%) in the FS-LASIK group were within ±1.00 D of target (P = 0.003). Root mean square (RMS) of corneal total HOA and vertical coma in the TPRK group were lower compared with the FS-LASIK group (P < 0.001 for both variables).

Conclusions

TPRK and FS-LASIK showed good safety, efficacy and predictability for correction of high myopia. Clinical outcomes of TPRK were slightly better than FS-LASIK.

Incidence of Intraoperative and Early Postoperative Adverse Events in a Large Cohort of Consecutive Laser Vision Correction Treatments

PURPOSE

To evaluate the incidence of adverse events (AE) following laser vision correction.

DESIGN

Retrospective case series.

METHODS

Optical Express, UK. Patients/study population: patients who underwent laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between July 1, 2014, and June 30, 2016. Intervention/observation procedures: all AEs recorded in the electronic medical record were extracted and retrospectively reviewed. The total incidence of AE and serious adverse events (SAE) was calculated. Loss of 2 or more lines of corrected distance visual acuity (CDVA) was calculated for the entire cohort of patients that attended a minimum of 3 months follow-up.

MAIN OUTCOME MEASURES

AEs; Preoperative and last available postoperative clinical data.

RESULTS

A total of 31,921 (61,833 eyes) were included in the study for LASIK and 5,016 (9,467 eyes) for PRK. The total number of AE was 850 for LASIK (occurring in 783 eyes of 657 patients; incidence of 1.3% or 1:79 eyes) and 227 for PRK (occurring in 218 eyes of 170 patients; incidence of 2.3% or 1:43 eyes). In the LASIK group, there were 287 SAEs (271 eyes of 226 patients; incidence of 0.4% or 1:228 eyes), and the number of SAEs in PRK group was 65 (65 eyes of 39 patients; incidence 0.7% or 1:146 eyes). Combining LASIK and PRK data, the loss of 2 or more lines of CDVA was recorded in 0.37% of eyes.

CONCLUSIONS

Contemporary LASIK and PRK are safe procedures with a low incidence of serious adverse events.

Ability of a new crosslinked polymer ocular bandage gel to accelerate reepithelialization after photorefractive keratectomy

PURPOSE

To evaluate the safety and performance of a crosslinked thiolated carboxymethyl hyaluronic acid liquid-gel (CMHA-S) ocular bandage gel in accelerating reepithelialization of corneal defects created for photorefractive keratectomy (PRK).

SETTING

Three community-based clinical research sites.

DESIGN

Prospective case series.

METHODS

Patients scheduled for bilateral PRK had both eyes randomized immediately after PRK to Group 1 (ocular bandage gel 4 times a day for 14 days and bandage contact lens), Group 2 (ocular bandage gel 4 times a day for 14 days), or Group 3 (control; bandage contact lens and artificial tears 4 times a day for 14 days). Patients received a 9.0 mm epithelial defect for PRK and were followed through 28 days postoperatively. Safety assessments included adverse events, vision, pain, slitlamp, intraocular pressure, and fundus examinations. The primary performance endpoint was time to corneal reepithelialization after PRK.

RESULTS

The study comprised 39 patients. The ocular bandage gel was well tolerated. The time to reepithelialization was 3 days for 54.5%, 80.0%, and 45.5% of patients in Group 1, Group 2, and Group 3, respectively. Compared with measurements in the control group, the mean horizontal and vertical defect lengths in Group 2 (ocular bandage gel alone) were 36.9% and 29.0% smaller, respectively, by 1 day.

CONCLUSION

Crosslinked hyaluronic acid showed the ability to quickly reepithelialize the cornea and may promise a well-tolerated and effective therapy for ocular wound care after trauma, disease, or surgery.

Safety and complications after three different surface ablation techniques with mitomycin C: a retrospective analysis of 2757 eyes

BACKGROUND

To evaluate the safety and spectrum of complications of three excimer laser surface ablation techniques (SATs) with an intraoperative application of mitomycin C (MMC) 0.02%. A retrospective, non-comparative large case series.

METHODS

SATs were performed on 2757 eyes with a preoperative spherical equivalent (SE) of - 4.41 ± 2.44 and a Wavelight Allegretto 200 platform. Ablation zone diameters between 6.0 and 7.0 mm were used according to mesopic pupil size. All patients were treated with an intraoperative application of MMC for 30 to 90 s depending on refractive error. The mean follow-up time was > 3 months (107 ± 24 days). Complication range and incidence were analyzed retrospectively and safety index was calculated.

RESULTS

Two thousand seven hundred and fifty-seven eyes met the inclusion criteria for surface ablation. Two thousand five hundred and seventy-three eyes were assigned to alcohol-assisted photorefractive keratectomy (APRK), 135 eyes to transepithelial photorefractive keratectomy (TPRK), and 49 eyes to off-flap epithelial laser in situ keratomileusis (EpiLASIK/EpiK). Overall, the safety index was 1.06 ± 0.28. Haze was graded according to the Fantes scale. Haze incidence rates were highest in the TPRK group (14.81%) and comparably low in APRK (2.95%) and EpiK (4.08%) groups.

CONCLUSIONS

Intraoperative topical application of MMC (0.02%) results in good safety and no severe side effects. However, highest incidence of haze was observed after TPRK. The more frequent peripheral localization of haze might be attributed to large ablation zones and the wavefront optimized ablation profile especially in the PTK modus of the laser platform.

Outcomes of photorefractive keratectomy in patients with atypical topography

Background

Photorefractive keratectomy (PRK) is at risk of serious complications such as corneal ectasia, which can reduce corrected distance visual acuity. The rate of complications of PRK is higher in patients with atypical topography.

Objective

To determine the outcomes of photorefractive keratectomy in patients with atypical topography.

Methods

This cross-sectional study was done in 2015 in Shiraz in Iran. We included 85 eyes in this study. The samples were selected using a simple random sampling method. All patients were under evaluation for uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction, corneal topography, central corneal thickness using pentacam, slit-lamp microscopy, and detailed fondus evaluation. The postoperative examination was done 1–7 years after surgery. Data were analyzed using IBM SPSS 21.0 version. To analyze the data, descriptive statistics (frequency, percentage, mean, and standard deviation), chi-square, and independent samples t-test were used.

Results

We studied 85 eyes. Among the patients, 23 (27.1%) were male and 62 (72.9%) were female. Mean age of the participants was 28.25±5.55 years. Mean postoperative refraction was – 0.37±0.55 diopters. Keratoconus or corneal ectasia was not reported in any patient in this study. There was no statistically significant difference between SI index before and after operation (p=0.736). Mean preoperative refraction was −3.84 ± 1.46 diopters in males and −4.20±1.96 diopters in females; thus there was not statistically significant difference (p = 0.435).

Conclusion

PRK is a safe and efficient photorefractive surgery and is associated with low complication rate in patients with atypical topography.

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

BACKGROUND

While 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).

METHODS

This 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.

RESULTS

Data 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.

CONCLUSION

LE 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.

Fifteen years follow-up of photorefractive keratectomy up to 10 D of myopia: outcomes and analysis of the refractive regression

PURPOSE

To evaluate outcomes of photorefractive keratectomy up to -10.00 D of myopia and -4.50 of astigmatism and to develop a predictive model for the refractive changes in the long term.

SETTING

Vissum Corporation and Miguel Hernandez University (Alicante, Spain).

DESIGN

Retrospective-prospective observational series of cases.

METHODS

This study included 33 eyes of 33 patients aged 46.79±7.04 years (range 40-57) operated with the VISX 20/20 excimer laser with optical zones of 6 mm. No mitomycin C was used in any of these cases. The minimum follow-up was 15 years. The main outcome measures were: uncorrected and corrected distance visual acuity, manifest refraction and corneal topography. Linear regression models were developed from the observed refractive changes over time.

RESULTS

Safety and efficacy indexes at 15 years were 1.18 and 0.83, respectively. No statistically significant differences were detected for any keratometric variable during the follow-up (p≥0.103). 15 years after the surgery 54.55% of the eyes were within ±1.00 D of spherical equivalent and 84.85% within ±2.00 D. The uncorrected distance visual acuity at 15 years was 20/25 or better in 60.6% of the eyes and 20/40 or better in 72.73% of the eyes. The correlation between the attempted and the achieved refractions was r=0.948 (p<0.001) at 1 year, and r=0.821 (p<0.001) at 15 years. No corneal ectasia was detected in any case during the follow-up.

CONCLUSIONS

Photorefractive keratectomy is a safe refractive procedure in the long term within the range of myopia currently considered suitable for its use, although its efficacy decreases with time, especially, in high myopia. The model developed predicts a myopic regression of 2.00 D at 15 years for an ablation depth of 130 µm.

Safety and Efficacy of Epi-Bowman Keratectomy in Photorefractive Keratectomy and Corneal Collagen Cross-Linking: A Pilot Study

PURPOSE

The purpose of this study is to compare the efficacy and safety of Epi-Bowman Keratectomy (EBK) using Epi-clear™ epikeratome with a mechanical scraper for corneal epithelium debridement during photorefractive keratectomy (PRK) and corneal collagen cross-linking (CXL).

METHODOLOGY

Sixty eyes of 30 patients undergoing PRK and 44 eyes of 44 patients undergoing CXL were included in this study. In the PRK group, one eye of each patient underwent EBK and the other eye epithelial debridement with a mechanical scraper. In the CXL group, 22 eyes of 22 patients underwent EBK and the other 22 eyes with a mechanical scraping to remove the epithelium. Intra-operative spectral domain optical coherence tomography (SD OCT; Bioptigen Inc, Durham, NC) was performed to evaluate the integrity of Bowman's membrane following epithelial removal. The time taken for epithelial removal, post-operative pain score using the Wong-Baker's pain scale, time for epithelial healing, and the epithelial profile using the Optovue (Optovue Inc. Fremont, CA) during the healing was observed and analyzed between the two groups and subgroups.

RESULTS

Intra-operative SD OCT showed a smooth and undamaged Bowman's membrane when EBK was performed. Post-operative pain was significantly less (p < 0.01 in the PRK group and p < 0.001 in the CXL group) with faster epithelial healing (p < 0.001 in the PRK group and p < 0.0001 in the CXL group) in the EBK subgroup as compared with the mechanical scraper subgroup. Epithelial profiling during the healing phase showed an edematous epithelium in the initial 2 weeks in the mechanical scraper subgroup while the EBK subgroup showed minimal epithelial edema lasting up to a week with regularized and smooth corneal epithelium healing.

CONCLUSION

Epi-Bowman Keratectomy appears to be an effective and safe method of corneal epithelial debridement with negligible damage to Bowman's membrane and the surrounding epithelium leading to early healing thereby reducing the post-operative pain and complications.

Four-year to seven-year outcomes of advanced surface ablation with excimer laser for high myopia

PURPOSE

We aimed to evaluate and compare outcomes after photorefractive keratectomy with cooling (cPRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopia.

METHODS

This was a retrospective, single-masked follow-up study of patients treated for myopia between 2007 and 2009 with cPRK or LASEK, using a high-frequency flying-spot excimer laser with eye-tracker (MEL80; Carl Zeiss, Jena, Germany). One eye of each patient was randomly chosen for analysis. Re-treated eyes were excluded.

RESULTS

Forty-six cPRK patients and 35 LASEK patients were included. Spherical equivalent averaged -7.69 ± 1.47 diopters (D) in cPRK eyes and -7.98 ± 2.06 D in LASEK eyes (p = 0.31) before surgery. The average follow-up time was 4.6 years in cPRK patients and 6.0 years in LASEK patients (p < 0.05). At final follow-up, no cPRK eyes and one LASEK eye (p = 0.46) had lost two lines of corrected distance visual acuity (CDVA). No eyes had significant haze at final follow-up, although trace haze was found in four cPRK eyes and six LASEK eyes (p = 0.44). However, at 6 weeks after surgery, zero cPRK eyes and nine LASEK eyes (p < 0.05) had significant haze. At final follow-up, 63 % of cPRK eyes and 35 % of LASEK eyes (p = 0.17) were within ±1.0 D of intended refraction. Finally, 100 % of cPRK patients and 92 % of LASEK patients (p = 0.87) were satisfied or very satisfied with the surgery at final follow-up.

CONCLUSION

cPRK and LASEK seemed safe and with high patient satisfaction 4 to 7 years after surgery for high myopia. However, cPRK was more effective than LASEK in reducing initial significant corneal haze.

Techniques, indications and complications of corneal debridement

The cornea is the most exposed surface of the eye and, as such, is vulnerable to external trauma and the risk of infection. Many corneal diseases alter shape, surface, and transparency and thus result in reduced vision. The external position of the cornea, however, lends itself to diagnostic and therapeutic maneuvers that are commonly performed and readily done in the clinic. More sophisticated techniques require the use of complex equipment such as excimer and femtosecond laser. Complications that develop from poor healing and/or secondary infection are best avoided with appropriate technique, antisepsis, and modification of wound healing. We review corneal debridement in the management of corneal disease.

Prospective, randomized, fellow eye comparison of WaveLight Allegretto Wave Eye-Q versus VISX CustomVueTM STAR S4 IRTM in photorefractive keratectomy: analysis of visual outcomes and higher-order aberrations

Background

The purpose of this study was to compare differences in visual outcomes, higher-order aberrations, contrast sensitivity, and dry eye in patients undergoing photorefractive keratectomy using wavefront-guided VISX CustomVue™ and wavefront-optimized WaveLight^® Allegretto platforms.

Methods

In this randomized, prospective, single-masked, fellow-eye study, photorefractive keratectomy was performed on 46 eyes from 23 patients, with one eye randomized to WaveLight Allegretto, and the fellow eye receiving VISX CustomVue. Three-month postoperative outcome measures included uncorrected distance visual acuity, corrected distance visual acuity, refractive error, root mean square of total and grouped higher-order aberrations, contrast sensitivity, and Schirmer’s testing.

Results

Mean values for uncorrected distance visual acuity (logMAR) were −0.03 ± 0.07 and −0.06 ± 0.09 in the wavefront-optimized and wavefront-guided groups, respectively (P = 0.121). Uncorrected distance visual acuity of 20/20 or better was achieved in 91% of eyes receiving wavefront-guided photorefractive keratectomy, and 87% of eyes receiving wavefront-optimized photorefractive keratectomy, whereas uncorrected distance visual acuity of 20/15 was achieved in 35% of the wavefront-optimized group and 64% of the wavefront-guided group (P ≥ 0.296). While root mean square of total higher-order aberration, coma, and trefoil tended to increase in the wavefront-optimized group (P = 0.091, P = 0.115, P = 0.459, respectively), only spherical aberration increased significantly (P = 0.014). Similar increases were found in wavefront- guided root mean square of total higher-order aberration (P = 0.113), coma (P = 0.403), trefoil (P = 0.603), and spherical aberration (P = 0.014). There was no significant difference in spherical aberration change when comparing the two platforms. The wavefront-guided group showed an increase in contrast sensitivity at 12 cycles per degree (P = 0.013).

Conclusion

Both VISX CustomVue and WaveLight Allegretto platforms performed equally in terms of visual acuity, safety, and predictability in photorefractive keratectomy. The wavefront-guided group showed slightly improved contrast sensitivity. Both lasers induced a comparable degree of statistically significant spherical aberration, and tended to increase other higher-order aberration measures as well.

Reducing peak corneal haze after photorefractive keratectomy in rabbits: prednisolone acetate 1.00% versus cyclosporine A 0.05%

PURPOSE

To compare the effects of topical cyclosporine A 0.05% (Restasis) with those of prednisolone acetate 1.00% (Pred Forte) on corneal haze after photorefractive keratectomy (PRK).

SETTING

Gavin Herbert Eye Institute, University of California, Irvine-Orange, California, USA.

DESIGN

Experimental study.

METHODS

After -9.00 diopter PRK, 15 rabbits were divided into 3 groups and treated for 4 weeks with prednisolone acetate 1.00% or cyclosporine A 0.05% or neither (control). Corneal haze was measured by in vivo confocal microscopy preoperatively and 2, 4, 6, 8, and 12 weeks postoperatively. At 12 weeks, the corneas were evaluated for collagen organization by ex vivo 2-photon second-harmonic generation and stromal cell density.

RESULTS

Corneal haze was significantly less in the prednisolone acetate group than in the cyclosporine and control groups during the first 6 weeks postoperatively (P<.02). At 8 weeks, there was no significant difference between the 3 groups. There was no significant difference in haze between the cyclosporine and control groups at any time. The stroma was also significantly thinner in the prednisolone acetate group than in the other groups for the first 4 weeks postoperatively (P<.02). Second-harmonic generation scar thickness measurements at 12 weeks were not significantly different between the groups, although the prednisolone acetate group tended to have lower stromal cell density.

CONCLUSION

Cyclosporine A 0.05% had no effect on wound healing after PRK, while prednisolone acetate 1.00% significantly reduced peak corneal haze but had no effect on long-term corneal haze after discontinuation of the drug.

Long-term follow-up of photorefractive keratectomy for myopia: Comparative study of excimer lasers

PURPOSE

To compare the long-term results of photorefractive keratectomy (PRK) for low to moderate myopia performed using a broad-beam laser system or a scanning-slit laser system.

SETTING

Department of Ophthalmology, University of Helsinki, Helsinki, Finland.

DESIGN

Case-control study.

METHODS

This follow-up study comprised eyes with myopia (-1.25 to -7.00 diopters [D]) or myopic astigmatism (astigmatism lower than -2.50 D) corrected by PRK using a broad-beam (Visx) or scanning-slit (Nidek) laser. Follow-up included a visit at 3 months and at more than 8 years. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refraction were recorded.

RESULTS

The broad-beam group comprised 27 eyes and the scanning-slit group, 34 eyes. At the last postoperative follow-up, the UDVA was 0.0 or better in 55% of eyes in the broad-beam group and 65% of eyes in the scanning-slit group. The CDVA was 0.0 or better in all eyes in the broad-beam group and 96% of eyes in the scanning-slit group. Regarding predictability, 48% and 73% of the eyes, respectively, were within ±0.50 D of the intended spherical equivalent refraction. There were no statistically significant differences between the 2 laser groups in any preoperative or postoperative parameter.

CONCLUSION

There were no significant differences in UDVA, CDVA, or SE after PRK for low to moderate myopia between the broad-beam laser system and the scanning-slit laser system.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Ten-year follow-up of photorefractive keratectomy for myopia

BACKGROUND

The aim of this study is to evaluate the long-term (10-year) outcome of excimer laser photorefractive keratectomy (PRK) on myopic eyes.

METHODS

This retrospective study included 42 eyes of 29 patients (13 male, 16 female; mean age 33.4 years, range 21 to 60) who were treated with myopic PRK at St. Luke's International Hospital, Tokyo, Japan, from May 1 1995 to December 31 1998, and followed up for more than 10 years. The main outcome measures were efficacy, predictability, stability, safety, and complications. We also evaluated the progress of intraocular pressure, corneal thickness, and endothelial cell density after the surgery. The cases of retreatments were excluded from this study.

RESULTS

Ten years after the surgery, 17 eyes (40%) had 20/20 vision or better, and 35 eyes (81%) had 20/40 or better. With regard to the refractive predictability, 55 percent of the eyes were within ± 1.0D and 76% were within ± 2.0D, 10 years after the surgery. There was myopic regression with a mean change in refraction of-0.51 ± 1.78D. Best spectacle-corrected visual acuity (BCVA) was unchanged or improved in 95%, and only two eyes lost 1 line of BCVA. The mean corneal haze score was 0.19 ± 0.40, and the decreasing rate of endothelial cell was 8.30 ± 9.94% at 10 years, which was slightly higher than the spontaneous decreasing rate with age.

CONCLUSIONS

PRK is safe and effective in refraction even 10 years after surgery; however, further long-term follow-up is needed to evaluate the decreasing of endothelial cells.

A new transepithelial phototherapeutic keratectomy mode using the NIDEK CXIII excimer laser

PURPOSE

To evaluate epithelial healing, postoperative pain, and best spectacle-corrected visual acuity (BSCVA) after transepithelial photorefractive keratectomy (PRK) performed with a new phototherapeutic keratectomy (PTK) mode using the NIDEK CXIII excimer laser.

METHODS

Fifteen eyes from 10 patients with myopia underwent transepithelial PRK using a multistage program to perform PTK followed by PRK. The PTK incorporated Flex Scan, which accounts for the loss of radial ablation efficiency on the peripheral cornea. The epithelium was removed with the excimer laser by monitoring the disappearance of blue fluorescence during the ablation. Epithelial healing was evaluated by taking slit-lamp photographs every 24 hours until complete reepithelialization. Postoperative pain was measured according to the Faces Pain Rating Scale. All outcomes are reported for 3 months postoperatively. Haze was graded by two ophthalmologists, each masked to the other's result.

RESULTS

Mean reepithelialization took 3.50+/-0.85 days, mean pain score was 3.00+/-1.20, and BSCVA was 20/20 for 9 eyes, 20/30 for 3 eyes, and 20/40 for 3 eyes. All patients had haze below grade 2.

CONCLUSIONS

The outcomes of the preliminary study show that the incorporation of the Flex Scan algorithm in the PTK mode is as safe and effective as conventional PTK algorithms. The primary advantage of this new PTK mode may be more consistent epithelial removal. Additional studies are needed to determine long-term outcomes.

Comparison of early postoperative clinical outcomes of photorefractive keratectomy and lamellar epithelial debridement

PURPOSE

To compare early postoperative clinical outcomes of photorefractive keratectomy (PRK) and lamellar epithelial debridement (LED).

SETTING

Department of Ophthalmology, Kangbuk Samsung Hospital, Seoul, Korea.

METHODS

This prospective study was of patients randomly assigned to have PRK or LED. In the LED group, an epithelial flap was created using an Amadeus II epikeratome. Postoperative follow-up was at 1, 3, and 7 days and 1, 3, and 6 months. The outcome parameters were uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), higher-order aberrations (HOAs), epithelial healing time, and corneal haze.

RESULTS

The study comprised 39 patients (76 eyes). The mean preoperative spherical equivalent (SE) was -3.96 diopters (D) +/- 1.24 (SD) in the PRK group and -4.06 +/- 1.39 D in the LED group. Postoperative UCVA was significantly better in the LED group 1 day postoperatively. The UCVA was 20/20 or better in 14.6% in the PRK group and 42.9% in the LED group (P = .006); 20/25 or better in 41.5% and 82.9%, respectively (P = .000); and 20/40 or better in 80.5% and 100%, respectively (P = .006). On subsequent follow-up visits, the UCVA was comparable between groups. No eye lost lines of BCVA at 3 months. There was no difference between groups in postoperative SE refraction, HOAs, or corneal haze.

CONCLUSIONS

Lamellar epithelial debridement and PRK had comparable safety and efficacy in the surgical correction of low to moderate myopia. The UCVA was significantly better after LED than after PRK 1 day postoperatively and equivalent thereafter.

Ten-year follow-up of photorefractive keratectomy for myopia of less than -6 diopters

PURPOSE

To evaluate the long-term outcomes of excimer laser myopic photorefractive keratectomy (PRK) for myopia of less than -6 diopters (D).

DESIGN

Long-term (10-year) follow-up retrospective, interventional case series.

METHODS

The study included 225 eyes of 138 myopic patients with spherical equivalent (SE) between 0 and -6 D treated with myopic PRK at the Instituto Oftalmológico de Alicante, Alicante, Spain, using the VISX 20/20 excimer laser (Santa Clara, California, USA). The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications.

RESULTS

At 10 years, 169 (75%) of 225 eyes were within +/- 1.00 D and 207 (92%) were within +/- 2.00 D. Ninety-five (42%) eyes underwent retreatments because of overcorrection, regression, or both. The mean SE slightly decreased (myopic regression) with a mean magnitude of -0.10 +/- 1.08 D over 10 years (-0.01 +/- 0.11 D per year). Forty-one (58%) of 225 eyes demonstrated increase in best spectacle-corrected visual acuity after 10 years. Only one eye lost eight lines because of significant cataract, and two eyes lost vision (one lost seven lines and the other lost four lines) because of posterior segment-related complications. The mean corneal haze score gradually decreased from 0.22 +/- 0.39 at three months to 0.01 +/- 0.09 at 10 years.

CONCLUSIONS

Photorefractive keratectomy for myopia of less than -6 D is a safe and effective procedure in the long-term.

Ten-year follow-up of photorefractive keratectomy for myopia of more than -6 diopters

PURPOSE

To evaluate the long-term outcomes of excimer laser myopic photorefractive keratectomy (PRK) for myopia higher than -6 diopters (D).

DESIGN

A long-term (10-year) follow-up retrospective, interventional case series.

METHODS

The study included 267 eyes of 191 patients with myopia with spherical equivalent (SE) of more than -6 D treated with myopic PRK at the Instituto Oftalmológico de Alicante, Alicante, Spain, using the VISX 20/20 excimer laser (Santa Clara, California, USA). All patients were evaluated three months, one year, two years, five years, and 10 years after surgery. The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications.

RESULTS

At 10 years, 156 (58%) of 267 eyes were within +/- 1.00 D and 209 (78%) were within +/- 2.00 D. One hundred and twenty-four eyes (46.4%) underwent retreatments because of overcorrection, regression, or both. The mean SE decreased (myopic regression) in eyes that did not undergo retreatment, with a mean magnitude of -1.33 +/- 2.0 D over 10 years (-1.13 +/- 0.20 D per year). One hundred and twenty-one (48.3%) of 267 eyes demonstrated increase in best spectacle-corrected visual acuity, and only eight eyes lost lines of vision because of cataract and posterior segment-related complications. The mean corneal haze score decreased gradually from 0.48 +/- 0.69 at three months to 0.09 +/- 0.33 at 10 years.

CONCLUSIONS

PRK for myopia of more than -6 D is a safe and effective procedure in the long-term.

Effects of acetylcysteine and dexamethasone on experimental corneal wounds in rabbits

Corneal wound healing often leads to the development of scar tissue with loss of transparency. Reconstitution of transparent corneal stroma depends on the regulation of the biosynthetic activities of post-lesional keratocytes as well as to a large extent on the limitation of matrix degradation. It has been shown that 3% concentration of N-acetylcysteine (NAC) improves the healing time of corneal wounds but some corneal haze remains. On the other hand, topical corticosteroids may retard the corneal wound healing but decrease the haze. Thus, the aim of the study was to evaluate whether adding dexamethasone to NAC could reduce the side effects of the two drugs. In this study, experimental corneal wounds were created surgically, up to the depth of one half of the stroma in the center of both eyes of all rabbits. The left eyes were treated topically with 0.9% NaCl as controls and the right eyes were treated with a combination of one drop of 3% NAC and one drop of 0.1% dexamethasone, 6 times per day. Corneal wounds were measured by fluorescein staining every day. The results indicated that the combination of acetylcysteine and dexamethasone significantly increased the mean healing time compared to the control group (p < 0.05). Clinical and histopathologic examinations revealed that the corneal haze in the treatment group was greater than in the control group. It is concluded that treatment of the eyes by a combination of 3% acetylcysteine and 0.1% dexamethasone (if used from the first day of ulceration) may retard the corneal wound healing in rabbits.

Early Postoperative Pain Following Epi-LASIK and Photorefractive Keratectomy: A Prospective, Comparative, Bilateral Study

PURPOSE

To compare postoperative pain associated with epi-LASIK versus photorefractive keratectomy (PRK).

METHODS

This prospective observer-masked randomized study included 40 eyes of 20 patients with myopia and astigmatism who received epi-LASIK (Moria Epi-K) in one eye and PRK in the contralateral eye. Corneal ablation was done using the NIDEK EC-5000 excimer laser. Patients were seen at days 1, 3, and 6 to rate their pain via three measuring tools: 1) a global subjective rating, 2) a 10-cm visual analog scale, and 3) an 11-point numeric scale of pain.

RESULTS

On postoperative day 1, 19 of 20 patients reported pain in both eyes. Using the global subjective rating scale, patients reported more pain for those eyes treated by PRK. Although clinically relevant, this difference was not statistically significant (P = .56). Based on the 11-point numeric scale of pain and visual analog scale, mean pain scores were similar for both groups. On day 3, using the global subjective rating scale, 11 of 12 patients who had pain reported more in the epi-LASIK treated eye (P = .0005). In addition, epi-LASIK eyes demonstrated higher mean pain scores based on the other two scales (visual analog scale, P = .045 and 11-point numeric scale of pain, P = .023). Only 6 patients reported minimal pain on day 6. It was more frequently reported and slightly more marked in epi-LASIK eyes, but did not reach statistical significance.

CONCLUSIONS

Epi-LASIK and PRK have similar pain on postoperative day 1, but epi-LASIK demonstrated statistically more pain than PRK on days 3 and 6.

Evidence for Superior Efficacy and Safety of LASIK over Photorefractive Keratectomy for Correction of Myopia

PURPOSE

To examine possible differences in efficacy and safety between LASIK and photorefractive keratectomy (PRK) for correction of myopia.

DESIGN

Meta-analysis/systematic review.

PARTICIPANTS

Patient data from previously reported prospective randomized controlled trials (PRCTs) and a systematic review of prospective case series in the Food and Drug Administration (FDA) clinical trials database.

METHODS

A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify PRCTs comparing LASIK and PRK for correction of myopia. A meta-analysis was performed on the results of PRCTs. In parallel, a systematic review of prospective data from FDA case series of LASIK and PRK for correction of myopia was undertaken.

MAIN OUTCOME MEASURES

Key efficacy outcomes (uncorrected visual acuity [UCVA] > or = 20/20, +/-0.50 diopters [D] of the target mean refractive spherical equivalent) and safety outcomes (loss of > or =2 lines of best spectacle-corrected visual acuity [BSCVA], final BSCVA > or = 20/40, and final BSCVA < 20/25 where preoperative BSCVA was > or =20/20).

RESULTS

Seven PRCTs were identified comparing PRK (683 eyes) and LASIK (403 eyes) for correction of myopia. More LASIK patients achieved UCVA > or = 20/20 at 6 months (odds ratio, random effects model [95% confidence interval], 1.72 [1.14-2.58]; P = 0.009) and 12 months (1.78 [1.15-2.75], P = 0.01). Loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.69 [1.01-7.18], P = 0.05). Data from 14 LASIK (7810 eyes) and 10 PRK (4414 eyes) FDA laser approval case series showed that more LASIK patients achieved UCVA of 20/20 or better at 12 months (1.15 [1.03-1.29], P = 0.01), significantly more LASIK patients were within +/-0.50 D of target refraction at 6 months (1.38 [1.26-1.50], P<0.00001) and 12 months (1.21 [1.08-1.36], P = 0.0009) after treatment, and loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.91 [2.22-3.83], P<0.00001).

CONCLUSIONS

LASIK appears to have efficacy and safety superior to those of PRK. However, the data examined are from studies conducted > or =5 years ago. It is therefore unclear how our findings relate to present-day methods and outcomes. Further trials comparing contemporary equipment and techniques are needed to reevaluate the relative merits of these procedures.

Clinical Results With the Medennium Phakic Refractive Lens for the Correction of High Myopia

PURPOSE

To evaluate the predictability, safety, stability, complications, and biocompatibility of the phakic refractive lens (PRL) as a posterior chamber intraocular lens to correct high myopia.

METHODS

Fifty eyes of 31 patients who underwent posterior chamber PRL implantation were evaluated prospectively. Mean preoperative myopia was -12.54 +/- 4.22 diopters (D) (range: -4.50 to -23.50 D) and mean astigmatic refractive power was -1.38 +/- 1.24 D (range: -1.00 to -4.50 D). Surgical implantation was performed through a 3.0- to 4.0-mm clear cornea sutureless incision using parabulbar (sub-Tenon's) anesthesia. Intra- and postoperative complications were recorded.

RESULTS

Three months after surgery, the mean spherical equivalent refraction was -0.21 +/- 0.42 D (range: +1.00 to -1.75 D). At 6 and 12 months, mean spherical equivalent refraction was -0.23 +/- 0.38 D (range: 0 to -1.25 D). At the last examination, uncorrected visual acuity was > or = 20/40 in 41 (82%) eyes and > or = 20/20 in 22 (44%) eyes. Best spectacle-corrected visual acuity (BSCVA) was > or = 20/40 in 42 (84%) eyes and > or = 20/20 in 27 (54%) eyes. Comparison of pre- and postoperative BSCVA at 12 months showed that 12 (36.4%) of 33 eyes gained > or =1 lines of BSCVA and 7 (21.2%) of 33 eyes gained > or =2 lines. One (2%) eye developed anterior subcapsular cataract requiring lens exchange, and 1 (2%) eye developed acute angle closure glaucoma requiring YAG-iridotomy. One (2%) eye developed macular hemorrhage.

CONCLUSIONS

At 6 months and 1 and 2 years, PRL implantation yielded encouraging visual and refractive results with excellent biocompatibility. The efficacy, stability, and short-term safety of this lens was established. Serious complications, such as cataract and acute angle closure glaucoma, may occur, and long-term safety needs to be evaluated.

Comparison of Laser Epithelial Keratomileusis With and Without the Use of Mitomycin C

PURPOSE

To analyze the results of prophylactic intraoperative use of mitomycin C (MMC) in laser epithelial keratomileusis (LASEK).

METHODS

A retrospective analysis of 30 LASEK cases that received MMC 0.02% intraoperatively (MMC group) was performed and compared to the results obtained in 28 LASEK cases not receiving MMC (no MMC group). Mitomycin C was placed in contact with the ablation zone for 75 seconds with an imbibed microsponge. Both groups received postoperative fluorometholone for 3 months. Preoperative spherical equivalent refraction was -5.72 +/- 2.82 diopters (D) in the MMC group and -5.81 +/- 2.74 D in the no MMC group. Best spectacle-corrected visual acuity was 0.88 +/- 0.12 in the MMC group and 0.88 +/- 0.13 in the no MMC group.

RESULTS

Spherical equivalent refraction at 6 months postoperatively was +0.11 +/- 0.13 D in the MMC group and +0.09 +/- 0.37 D in the no MMC group. Best spectacle-corrected visual acuity was 0.90 +/- 0.13 in the MMC group and 0.88 +/- 0.13 in the no MMC group. Uncorrected visual acuity (UCVA) > or = 20/40 was obtained in 93.3% of cases in the MMC group and in 89.3% of cases in the no MMC group; UCVA > or = 20/25 was achieved in 76.6% of cases in the MMC group and in 71.4% of cases in the no MMC group. Haze incidence for the MMC group was: trace: 0%, Grades I: 0%, II: 0%, III 0%, IV: 0%, and for the no MMC group: trace: 17.9%, Grades I: 3.6%, II: 0%, III: 0%, IV: 0%. A statistically significant difference (P<.001) was noted in haze intensity between the MMC group and no MMC group.

CONCLUSIONS

Prophylactic use of intraoperative MMC in LASEK significantly decreases haze incidence.

Laser in situ keratomileusis: ablation on the flap and stromal bed in a primary treatment

PURPOSE

To analyze outcomes of laser in situ keratomileusis (LASIK) performed on the flap and on the stromal bed at the same time in a primary treatment.

SETTING

Instituto de la Visión, Buenos Aires, Argentina.

METHODS

Twenty-two cases (13 female, 9 male) were studied retrospectively; the mean age of the patients was 33.15 years +/- 10.44 (SD). Inclusion criteria were low pachymetry or topographic asymmetry. Twenty cases (90.9%) presented with low pachymetry (512.2 +/- 21.40 mum), and 2 cases (9.1%) presented with topographic asymmetry (inferior-superior difference more than 1.5 diopters [D]). Ablation was performed on the flap from the back and on the bed. The flap was made using the Technolas Hansatome microkeratome and the ablation by the Technolas 217z excimer laser (both by Bausch & Lomb). Preoperatively, the spherical equivalent (SE) was -5.61 +/- 1.72 D, the cylinder was -1.78 +/- 1.24 D, and the best spectacle-corrected visual acuity (BSCVA) was 0.77 +/- 0.19. Difficulties and complications of the technique, efficacy and safety index, and aberrations were analyzed.

RESULTS

According to the surgical plan and our nomogram, diopters corrected on the flap were -1.73 +/- 1.08 and on the bed were -4.77 +/- 1.89. The mean follow-up was 8.28 +/- 2.19 months. At 6 months, the SE was -0.21 +/- 0.39, vectorial change was 1.69 +/- 0.74, and the BSCVA was 0.77 +/- 0.20. Postoperatively, no eye had an increase in refractive astigmatism. Uncorrected visual acuity was 20/40 or better in all cases (100%) and 20/25 or better in 13 cases (59.1%). Regarding gained and lost lines of BSCVA, 54.5% conserved the lines, 18.2% lost 1 line, 9.1% gained 1 line, and 18.2% gained 2 lines.

CONCLUSIONS

Simultaneous ablation on the flap and on the bed in cases of low pachymetry or topographical asymmetry was predictable, effective, and safe.

Evidence for Delayed Presbyopia after Photorefractive Keratectomy for Myopia

PURPOSE

To evaluate uncorrected near visual acuity (NVA), accommodation, corneal aberrations, and the optical quality of the retinal image in presbyopic eyes after photorefractive keratectomy (PRK).

DESIGN

Nonrandomized comparative retrospective study.

PARTICIPANTS

Ten post-PRK patients and 10 normal patients.

METHODS

Twenty eyes (10 right and 10 left after PRK for myopia, minimum of 10 years after the operation; group A) were compared with 20 eyes (10 right and 10 left age- and gender-matched normal controls; group B). All subjects were over 40 years of age.

MAIN OUTCOME MEASURES

With best distance correction, NVA was measured at 40 cm (Jaeger, J series), and the range of accommodation (diopters [D]) was measured subjectively (negative relative amplitude and positive relative amplitude). The modulation transfer function (MTF) and corneal aberrations such as comalike, spherical (SAs), and higher order (HOAs) were measured with a Hartmann-Shack aberrometer. From the MTF curves, the spatial frequencies corresponding to contrast values of 0.1 and 0.5 were noted.

RESULTS

Mean ages (+/- standard deviations [SDs]) were 46.3 years (4.7) for group A and 47.6 years (4.9) for group B (P>0.05). Near acuity was J1 or better in 12 of 20 post-PRK and 4 of 20 control eyes. Mean accommodations (+/- SDs) were 3.2 D (1.14) for right group A eyes and 2.1 D (0.94) for right group B eyes (P = 0.0152), and 3.4 D (0.99) for left A eyes and 2.3 D (1.02) for left B eyes (P = 0.0168). Total HOA indexes (+/- SDs) were 1.449 (0.409) for right group A eyes and 0.824 (0.241) for right group B eyes (P = 0.008), and 1.464 (0.388) for left A eyes and 1.067 (0.542) for left B eyes (P = 0.0752). Pooling the data from post-PRK and control eyes, a significant correlation was found between near acuity and SA (right eyes, r = -0.535, P = 0.015; left eyes, r = -0.493, P = 0.027). Significant associations were found between accommodation, near acuity, HOA, and comalike aberration for right eyes only. Mean spatial frequencies (+/- SDs) corresponding to contrast values of 0.1 for right and left eyes were 14.96 (5.71) for right group A eyes and 22.02 (6.85) for right group B eyes (P = 0.074), and 15.11 (7.80) for left A eyes and 21.41 (9.00) for left B eyes (P = 0.271). Mean spatial frequencies (+/- SDs) corresponding to contrast values of 0.5 for right and left eyes were 2.86 (0.63) for right group A eyes and 3.21 (0.35) for right group B eyes (P = 0.596), and 2.76 (0.98) for left A eyes and 3.22 (0.27) for left B eyes (P = 0.194).

CONCLUSIONS

Compared with normal eyes, in previously myopic eyes treated with first-generation PRK lasers there is a tendency for (1) the optical quality of the retinal image to be reduced at low contrast, (2) the aberrations attributed to the corneal surface to increase, and (3) both measured subjective accommodation and near acuity to be greater than expected. We postulate that the corneal aberrations induced by PRK for myopia may reduce the quality of the retinal image for distance but enhance near acuity by way of a multifocal effect that can delay the onset of age-related near vision symptoms.

LASIK in Myopic Patients With Dermatological Keloids

PURPOSE

To evaluate the visual and refractive out come of LASIK in myopic patients with a known history of dermatological keloid scar.

METHODS

This retrospective case series included 10 eyes of 5 white patients with a known history of dermatological keloids. All patients had low to moderate myopia with no corneal or limbal keloid. All underwent uneventful bilateral LASIK. Postoperatively, visual outcomes, refractive outcomes, and complications were evaluated. Minimum 1-year follow-up was indicated for all patients in this study.

RESULTS

Mean preoperative uncorrected visual acuity (UCVA) was 20/320 and 1 year postoperative 20/20. Mean preoperative best spectacle-corrected visual acuity (BSCVA) was 20/25 and 1 year postoperative was 20/20. The mean preoperative spherical equivalent refraction was -5.00 +/- 2.6 diopters (D) and +0.1 +/- 0.2 D 1 year postoperative. The safety index was 1.02 and the efficacy index was 1.02. None of the included in this study underwent retreatment for correction of residual error or regression up to 1 year postoperatively. No sight-threatening complications were reported. No patient reported postoperative haze, severe dry eye syndrome, or flap-related problems.

CONCLUSIONS

LASIK is a safe, effective, and predictable technique for correcting low and moderate myopia in patients with dermatological keloids.

Mitomycin C, Ceramide, and 5-Fluorouracil Inhibit Corneal Haze and Apoptosis After PRK

PURPOSE

To investigate the effects of mitomycin C (MMC), ceramide, and 5-fluororacil (5-FU) on haze after photorefractive keratectomy (PRK) and exposure to ultraviolet B (UVB) radiation.

METHODS

The right eyes of 42 New Zealand white rabbits were treated with PRK to correct -10 diopter with a 5-mm optical zone. Sponges soaked in 0.02% MMC, 10 or 40 micromol/L ceramide, or 0.5% 5-FU were applied to the right eyes of 6 rabbits each, and a tarsorrhaphy was performed. Eight weeks after complete healing, topical 0.02% MMC or 0.5% 5-FU was applied twice daily to the right eyes of 6 rabbits that had previously received PRK but no topical medication. The control group of 6 rabbits was treated only with PRK. Three weeks after PRK, all the laser-treated eyes were exposed to 100 mJ/cm UVB radiation. Corneal haze was assessed biomicroscopically every 2 weeks using the Fantes scale. Eyes were enucleated 2, 7, and 13 weeks after PRK, and tissue specimens were stained with hematoxylin and eosin and with Apostain.

RESULTS

Corneal haze was observed in all rabbits after PRK and was aggravated by UVB irradiation. When applied immediately after PRK, MMC induced corneal opacity and apoptosis of keratocytes, but, at later times, this reagent significantly suppressed opacity, Apostain-positive keratocytes and reactivation of keratocytes, even after UVB irradiation. In contrast, ceramide and 5-FU suppressed corneal opacity after PRK, but this effect was not sustained after UVB irradiation.

CONCLUSIONS

MMC is a potent inhibitor of haze induced by PRK and UVB irradiation. Throughout the process of corneal wound healing, the severity of apoptosis and reactivation of keratocytes was closely correlated with haze formation.

Conductive Keratoplasty for the Correction of Residual Hyperopia After LASIK

PURPOSE

To report the 6-month results concerning efficacy, safety, predictability, and stability of conductive keratoplasty for the correction of residual hyperopia after corneal refractive surgery.

METHODS

A total of 35 eyes (26 patients) with residual hyperopia after corneal refractive surgery ranging between +1.00 to +4.75 diopters (D) of spherical equivalent refraction were enrolled in the study and underwent conductive keratoplasty following a modified nomogram.

RESULTS

Variables and data were available for all eyes at 6 months postoperatively. A total of 24 (69%) eyes had uncorrected visual acuity (UCVA) of > or = 20/40, and 10 (29%) eyes had UCVA of 20/20. Manifest refractive spherical equivalent was within +/- 0.50 D in 17 (49%) eyes and within +/- 1.00 D in 25 (71%) eyes in cases of previous hyperopic LASIK; the optical zone was significantly increased.

CONCLUSIONS

Using a modified nomogram, conductive keratoplasty for correction of residual hyperopia was effective, but predictability was not satisfactory and safety needs to be established.

Effects of topical tranilast on corneal haze after photorefractive keratectomy

PURPOSE

To determine whether topical tranilast might reduce corneal haze through suppression of transforming growth factor (TGF)-beta1 synthesis in keratocyte after photorefractive keratectomy.

SETTING

Department of Ophthalmology, Korea University College of Medicine, Seoul, Republic of Korea.

METHODS

Photorefractive keratectomy was performed on 48 eyes of 28 white rabbits and 24 eyes in a tranilast group were treated with tranilast solution, and the other 24 eyes in control group were treated with saline after laser ablation. The grades of corneal haze at 1, 2, 4, and 8 weeks after surgery were evaluated in 10 eyes of each group for comparison. Immunohistochemistry was performed on 10 eyes of each group, and Western blot analysis was done on 4 eyes of each group for studying TGF-beta1 expression at postoperative day 7.

RESULTS

There was no statistically significant difference in corneal haze between 2 groups from week 1 to week 4 after surgery, but a significant difference was found at week 8 after photorefractive keratectomy (P=.02). The mean number of keratocytes that expressed TGF-beta1 in the tranilast group was 58.3 (+/-17.2), which showed significant difference, compared with that of the control group, 104.5 (+/-23.0) (P<.01). Western blot analysis also revealed that the amount of TGF-beta1 in tranilast group was slightly less than the control group.

CONCLUSIONS

Topical tranilast could reduce corneal haze by suppressing TGF-beta1 expression in keratocytes after photorefractive keratectomy.

Décollement de rétine post laser Excimer (Lasik/PKR myopique)

INTRODUCTION

Refractive surgery by LASIK or photorefractive keratectomy (PRK) generaly aims at a myopic population that has a high probability of developing rhegmatogenous retinal detachment (RD). The authors report a multicenter study with 15 cases of RD appearing after refractive surgery by Excimer laser and discuss the role played by the techniques used.

MATERIAL AND METHODS

Five centers fitted with nine Excimer laser devices took part in this study. Of 22,700 eyes undergoing refractive myopic surgery during the period 1994-2002, 15 eyes developed rhegmatogenous RD. The average age of the patients with RD was 37 years. The average myopia was 13.5 D. RD occurred a mean of 20 months after refractive laser.

RESULTS

Fifteen eyes of 13 patients developed a rhegmatogenous RD, two of which were bilateral. Eight of these cases had LASIK surgery and six had photorefractive keratectomy; one of the latter patients was retreated with LASIK because of substantial regression after PRK. RD was total or subtotal in five eyes, partial superior with a temporal tear in six eyes, and nasal in three eyes. One case with inferior RD, two cases with giant retinal tear and one case with posterior tear were also repaired. Fourteen eyes were suitable for operation. The retina was reattached in 12 cases. Mean postoperative visual acuity was 7/10.

DISCUSSION

The occurrence of rhegmatogenous RD in the myopic population is estimated at 2.2%. It is estimated at 0.1% in the emmetropic population. The Excimer laser, through its thermic effects, shock wave, traumatism undergone by the suction ring at the time of LASIK surgery, could increase this risk in myopic patients. A review of the literature cast doubt on the cause and effect hypothesis. Personal and multicenter studies (including ours) show that the frequency rate of rhegmatogenous RD after Excimer laser is equivalent and even lower than that estimated with an emmetropic population. The low percentage of RD after Excimer surgery found in the literature as well as in our study (<0.1%) may be explained by patient selection, the systematic monitoring of the peripheral fundus, and the prophylactic treatment of degenerative lesions by photocoagulation. In RD surgery, the cornea must be manipulated carefully, a case of flap dehiscence has been reported in the literature.

CONCLUSION

Refractive surgery by LASIK or PRK for severe myopia increases the risk of RD. Systematically monitoring the peripheral fundus and preventive photocoagulation have mitigated its occurrence, and the risk incurred in the myopic population has fallen to the emmetropic population's rate. Nevertheless, candidates for LASIK or PRK surgery must be informed because severe myopia constitutes a non-negligible risk factor.

Pathologic findings in postmortem corneas after successful laser in situ keratomileusis

PURPOSE

To examine the histologic and ultrastructural features of human corneas after successful laser in situ keratomileusis (LASIK).

METHODS

Corneas from 48 eyes of 25 postmortem patients were processed for histology and transmission electron microscopy (TEM). The 25 patients had LASIK between 3 months and 7 years prior to death. Evaluation of all 5 layers of the cornea and the LASIK flap interface region was done using routine histology, periodic acid-Schiff (PAS)-stained specimens, toluidine blue-stained thick sections, and TEM.

RESULTS

In patients for whom visual acuity was known, the first postoperative day uncorrected visual acuity was 20/15 to 20/30. In patients for whom clinical records were available, the postoperative corneal topography was normal and clinical examination showed a semicircular ring of haze at the wound margin of the LASIK flap. Histologically, the LASIK flap measured, on average, 142.7 microm (range, 100-200). A spectrum of abnormal histopathologic and ultrastructural findings was present in all corneas. Findings at the flap surface included elongated basal epithelial cells, epithelial hyperplasia, thickening and undulations of the epithelial basement membrane (EBM), and undulations of Bowman's layer. Findings in or adjacent to the wound included collagen lamellar disarray; activated keratocytes; quiescent keratocytes with small vacuoles; epithelial ingrowth; eosinophilic deposits; PAS-positive, electron-dense granular material interspersed with randomly ordered collagen fibrils; increased spacing between collagen fibrils; and widely spaced banded collagen. There was no observable correlation between postoperative intervals and the severity or type of pathologic change except for the accumulation the electron-dense granular material.

CONCLUSIONS

Permanent pathologic changes were present in all post-LASIK corneas. These changes were most prevalent in the lamellar interface wound. These changes along with other pathologic alterations in post-LASIK corneas may change the functionality of the cornea after LASIK.

Korneale Wundheilungsreaktionen nach hyperoper PRK und LASIK

BACKGROUND

The purpose of this study was to investigate the influence of different postoperative treatments on the wound healing reaction in the anterior stroma after PRK and in the interface area after LASIK.

METHODS

Seventy-two corneal buttons of refractively treated rabbit eyes underwent different postoperative eyedrop regimens with antibiotics and/or steroids or additional UV-B irradiation. Morphological and immunohistological investigations were performed 6 months postoperatively by light and transmission electron microscopy.

RESULTS

PRK eyes showed interdigitations between the epithelia and the anterior stroma. LASIK-treated eyes showed only minor changes between epithelia and stroma in the incisional region. Only a slight increase in deposits of fibrillar extracellular matrix components were detectable in the interface region.

CONCLUSIONS

The clinically important problem of haze after PRK is caused by the interdigitations between epithelia and anterior stroma. The delicate wound healing reactions in the interface region in LASIK eyes corresponded to the clinically visible minor changes in these corneas.

Epithelial healing and clinical outcomes in excimer laser photorefractive surgery following three epithelial removal techniques: mechanical, alcohol, and excimer laser

PURPOSE

To evaluate epithelial healing, postoperative pain, and visual and refractive outcomes after photorefractive keratectomy (PRK) using three epithelial removal techniques.

DESIGN

Prospective, nonrandomized, comparative trial.

METHODS

SETTING

Department of Ophthalmology, Yonsei University College of Medicine and Balgensesang Ophthalmology Clinic, Seoul, Korea.

INTERVENTIONS

For the PRK procedure, the corneal epithelium was removed in one of three ways: mechanically (conventional PRK [PRK]) in 88 eyes of 44 patients; using excimer laser (transepithelial PRK [tPRK]) in 106 eyes of 53 patients; or using 20% diluted alcohol, laser-assisted subepithelial keratomileusis (LASEK) in 106 eyes of 53 patients.

MAIN OUTCOME MEASURES

Epithelial healing, postoperative pain, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and remaining refractive error.

RESULTS

The mean postoperative pain scores were 4.84 +/- 1.45 for PRK, 4.71 +/- 1.62 for tPRK, and 4.63 +/- 1.52 for LASEK (P = .125). The mean epithelial healing rates were 12.3 +/- 4.6 for PRK, 15.2 +/- 4.9 for tPRK, and 18.1 +/- 5.2 mm2/day for LASEK (P < .001). The postoperative 6-month remaining mean spherical equivalents (diopters) were -0.46 +/- 1.01 for PRK, 0.18 +/- 0.91 for tPRK, and -0.82 +/- 1.18 for LASEK (P = .01). The LASEK group showed less favorable UCVA than other groups. There was no significant difference in BSCVA between the groups.

CONCLUSIONS

Postoperative pain, subepithelial opacity and BSCVA were similar regardless of the epithelial removal procedure. A faster epithelial healing rate did not result in better visual or refractive outcomes. Using the same nomogram, tPRK resulted in a slight overcorrection, and LASEK resulted in a slight undercorrection.

Automated superficial lamellar keratectomy augmented by excimer laser masked PTK in the management of severe superficial corneal opacities

AIM

To assess superficial lamellar keratectomy augmented by excimer laser smoothening with sodium hyaluronate 0.25%, for the management of superficial corneal opacities.

METHODS

Consecutive procedure performed in 14 eyes (13 patients) with an automated microkeratome and excimer laser phototherapeutic keratectomy (PTK) smoothening using sodium hyaluronate 0.25%.

MAIN OUTCOME MEASURES

UCVA, BCVA, pachymetry, degree of haze, ray tracing analysis, and complications. Mean follow up was 12 (SD 1.6) months.

RESULTS

Mean preoperative haze from previous corneal refractive surgeries was 3.5 (SD 0.5) (11/14 cases). In one case, opacity was caused by ocular trauma and in two by infectious keratitis. The mean preoperative UCVA was 0.7 logMAR (0.2 (SD 0.13) decimal value). BCVA was 0.4 logMAR (0.4 (SD 0.17) decimal value). Mean preoperative corneal pachymetry was 508 (SD 62.5) micro m and mean opacity depth measured by corneal confocal microscopy was 115.2 (SD 49.4) micro m. At 6 months, 71.4% of the eyes with previous corneal refractive surgery showed grade I haze or less. Mean postoperative corneal pachymetry at 6 months was 352.36 (SD 49.05) micro m.

CONCLUSIONS

Automated superficial lamellar keratectomy combined with excimer laser PTK smoothening assisted by sodium hyaluronate 0.25% induces a significant improvement of corneal transparency and visual acuity in cases of corneal opacity caused by previous refractive surgery, ocular trauma, and keratitis.

Update on laser subepithelial keratectomy (LASEK)

PURPOSE OF REVIEW

This study reviews current concepts in laser subepithelial keratectomy (LASEK), variations in LASEK techniques, the role of pharmacology in LASEK, and optimizing outcomes in LASEK.

RECENT FINDINGS

Recent studies continue to support the use of LASEK over that of LASIK in the correction of refractive error. In addition, the advent of pharmacological/biologic intervention, improved algorithms, and wavefront technology have expanded the armamentarium available to ophthalmologists in the maximization of LASEK outcomes.

SUMMARY

LASEK offers an excellent profile in terms of both final outcome (uncorrected visual acuity) and safety (best corrected visual acuity). Untoward effects of LASEK are readily prevented/treated with a variety of agents. Postoperative pain can be ameliorated using topical and oral analgesia. Infection can be most effectively addressed with the fourth generation of fluoroquinolones. Haze may be treated or prevented using numerous remedies namely autologous serum, steroids, ascorbic acid, mitomycin-c, and NSAIDS. Wavefront combined with LASEK rather than with LASIK may offer the best refractive outcome.

Laser in situ keratomileusis versus laser-assisted subepithelial keratectomy for the correction of high myopia

PURPOSE

To compare the visual and refractive outcomes of laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) in the treatment of high myopia.

SETTING

Institute of Vision Research, Department of Ophthalmology, College of Medicine, Yonsei University, and Balgeunsesang Ophthalmology Clinic, Seoul, South Korea.

METHODS

Four hundred seventy eyes of 240 patients with manifest refraction spherical components greater than -6.00 diopters (D) were assigned to 2 groups: 324 eyes (167 patients) were treated with LASIK and 146 eyes (73 patients), with LASEK. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), remaining refractive error, corneal haze, and complications were followed in both groups for 12 months.

RESULTS

At 12 months, the mean spherical equivalent (SE) was within +/-0.50 D of emmetropia in 205 eyes (63.3%) in the LASIK group and 81 eyes (55.5%) in the LASEK group and within +/-1.00 D in 261 eyes (80.6%) and 104 eyes (71.2%), respectively. The UCVA was 20/25 or better in 269 LASIK eyes (83.0%) and 111 LASEK eyes (76.0%). There was more than a 1-line loss of BSCVA in 4 LASIK eyes (1.2%) and 21 LASEK eyes (14.3%). The between-group differences in SE, magnitude of cylinder, UCVA, and haze were statistically significant (P<.05).

CONCLUSIONS

Both LASIK and LASEK were safe and effectively treated eyes with high myopia. Laser in situ keratomileusis provided superior results in visual predictability and corneal opacity.