Retinal detachment in myopic eyes after photorefractive keratectomy

PURPOSE: To analyze the incidence and characteristics of retinal detachment (RD) in myopic patients who had photorefractive keratectomy (PRK). SETTING: Universidad Miguel Hernández, Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: The incidence of RD in 5936 consecutive eyes that had PRK to correct myopia was studied. Mean follow-up was 38.5 months +/- 17.4 (SD). RESULTS: Retinal detachment occurred in 5 eyes (0.08%); 2 in women and 3 in men. The mean interval between PRK and RD was 21. 00 +/- 15.89 months (range 9 to 48 months). The mean best corrected visual acuity (BCVA) after PRK and before RD development was 20/81 (range 20/200 to 20/25). After RD repair, the mean BCVA was 20/460 (range 20/2000 to 20/29). In 4 of the 5 eyes, BCVA after RD was within 1 line of the preoperative value; in 1 eye, it decreased from 20/40 to 20/2000. The mean spherical equivalent (SE) before RD treatment was -1.35 +/- 1.08 diopters (D) (range 0 to -3.00 D) and after RD treatment, -2.95 +/- 0.83 D (range -2.00 to -4.00 D). Differences between SE before and after RD treatment were statistically significant (P =.01, paired Student t test). CONCLUSIONS: The incidence of RD after PRK to correct myopia was 0.08%. In 4 of 5 eyes, there was little or no visual loss; but in the group as a whole, there was a significant increase in myopic SE.     

Choroidal neovascularization in myopic eyes after laser-assisted in situ keratomileusis

PURPOSE: To analyze the appearance and characteristics of choroidal neovascularization (CNV) in patients with high myopia corrected by laser-assisted in situ keratomileusis (LASIK). PATIENTS AND METHODS: The authors studied CNV in 2955 consecutive eyes (1632 patients) that underwent LASIK for the correction of myopia (from -6 to -27.5 diopters). Follow-up was 34.2+/-11.3 months. RESULTS: Choroidal neovascularization occurred in three eyes (0.10%) and in one eye previous CNV was reactivated (three women, one man). The time interval between refractive surgery and CNV was 13+/-9.5 months (range, 4-26 months). Mean best-corrected visual acuity (BCVA) after LASIK and before CNV development was 20/57 (range, 20/100-20/29). After the appearance of CNV, mean BCVA was 20/606 (range, 20/2000-20/80). Differences between BCVA before and after CNV were statistically significant (P = 0.04, paired Student's t-test). The CNV was treated in two cases by argon laser photocoagulation and in two cases by surgical excision of CNV by vitrectomy. The final mean BCVA was 20/277 (range, 20/800-20/50). Differences between BCVA after LASIK and after CNV treatment were statistically significant (P = 0.04, paired Student's t-test). CONCLUSIONS: Laser-assisted in situ keratomileusis as a correcting procedure for myopia was followed by low appearance of CNV. The appearance and treatment of CNV was followed by a significant decrease of BCVA.     

Excimer laser photorefractive keratectomy in myopic eyes with corectopia.

Corectopia, the eccentric displacement of the pupil, may be associated with other abnormalities such as axial high myopia or ectopia lentis. We report the case of a patient presenting for surgery to correct bilateral myopia of 6.50 diopters (D) associated with corectopia. Excimer laser ablation was decentered and performed on the center of the abnormal pupils. After a 2 year follow-up, best corrected visual acuity was 20/20 with -1.00 D correction in each eye. To our knowledge, this is the first report of excimer laser photorefractive keratectomy for myopia associated with corectopia. The satisfactory results suggest that in abnormally eccentric pupils, excimer laser treatment of myopia may be successful when it is centered on the deviated pupil.     

Choroidal neovascularization in myopic eyes after phakic refractive lens and iris-claw lens implantation

PURPOSE: To describe the appearance of choroidal neovascularization (CNV) in two myopic patients after implantation of a phakic refractive lens (PRL) and an iris-claw lens. METHODS: A PRL was implanted in the left eye of a 35-year-old myopic man. Five weeks later, he reported decreased best-corrected visual acuity (BCVA). Fluorescein angiography revealed juxtafoveal CNV Photodynamic therapy with Visudyne (PDT) was successfully performed, achieving closure of the membrane. BCVA was 20/40 3 months afterwards. An iris-claw lens was implanted in the left eye of a 24-year-old myopic man. BCVA after surgery was 20/40 (SE -0.75). Three years later subfoveal CNV was diagnosed. PDT was performed, achieving complete closure of CNV BCVA was 20/100 3 months after treatment. CONCLUSIONS: The appearance of CNV in myopic eyes corrected by phakic intraocular lens implantation is a possible complication that must be considered.     

Choroidal neovascularization occurring concurrently in myopic eyes of monozygotic twins

PURPOSE: To present young monozygotic twins both of whom developed choroidal neovascularization at the same time. CASE/OBSERVATIONS: Monozygotic twins, 22-year-old women, who lived in the same house, developed choroidal neovascularization in the left eye at the same time. The degree of myopia was higher in the left eye (-7.75 and -8.5 dpt in spherical equivalent) than in the right eye (-6.75 and -4.5 dpt) of both patients. The choroidal neovascularization regressed in a different time course and the visual acuity returned to normal in both patients. CONCLUSION: This pair of monozygotic twins suggests that both genetic and environmental factors underlie the development of choroidal neovascularization in myopic eyes.     

准分子激光屈光性角膜切削术后眼压测量值的变化

目的：探讨影响准分子激光屈光性角膜切削术（laser photorefractive keratectomy,PRK)后眼压测量值变化的因素。方法：对209例（364只眼）近视患者行PRK,手术前、后采用Goldemann压平式眼压计测量患者的眼压,并测量角膜厚度和角膜曲率,进行量角膜厚度和角膜曲率,进行统计学分析。术后随访时间＞1年。结果：术后6个月和12个月术眼的眼压测量值低于术前,差异有非常显著意义（P＜0．001）,术后12个月的眼压测量值低于术后6个月,差异有非常显著意义（P＜0．001）,术后12个月的眼压测量值低于术后6个月,差异有非常显著意义（P＜0．001）。术后眼压测量值的降低与角膜厚度的减少和角膜曲率的降低均呈高度正相关（P＜0．01）,其二元回归方程为Y（手术前、后眼压差,mmHg）＝1．156＋0．022X1（手术前、后角膜厚度差,μm)＋0．052X2（手术前、后角膜曲率差,D）。结论：PRK术后眼压测量值低于术前;角膜厚度和角膜曲率是导致手术前、后眼压测量值变化的因素。     

Determining corneal power using Pentacam after myopic photorefractive keratectomy

Purpose: To assess the accuracy of Pentacam Scheimpflug camera for corneal power measurement in eyes with previous photorefractive keratectomy for myopia. Methods: In this comparative interventional case series, 35 eyes of 35 patients who had myopic photorefractive keratectomy were studied. Corneal power was measured by conventional topography and Pentacam Scheimpflug camera, and equivalent keratometry readings (EKR) in different central corneal rings (0.5 to 4.5 mm), true net power and simulated keratometry (K) measurements as well as those obtained using Shammas no‐history, Koch‐Maloney and Haigis methods were compared with clinical history method. Results: All corneal power measurements except for the topography simulated K and true net power values were statistically similar to the clinical history values. Simulated keratometry and 4.5‐mm EKR values were more closely correlated with clinical history method. Shammas formula, Pentacam simulated K and 3‐, 4‐ and 4.5‐mm EKR provided a 95% confidence interval within ±0.50 D of the mean clinical history method value, among these, the width of the 95% limits of agreement (LoA) was narrower for Shammas and Pentacam simulated K and 4.5‐mm EKR values; however, considerably large 95% LoA were found between each of these values and those obtained with the clinical history method. Estimated preoperative keratometry was statistically similar to the preoperative measurement; however, estimated refractive change was different from actual value. Conclusions: The Pentacam 4.5‐mm EKR and simulated keratometry may be used as an alternative to clinical history method to predict corneal power when pre‐keratorefractive surgery data are unavailable; however, wide LoA should be considered in the calculations.     

Surgically induced astigmatism after hyperopic and myopic photorefractive keratectomy

PURPOSE: To compare the axis and magnitude of surgically induced refractive astigmatism (SIA) after hyperopic and myopic photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: In this single-center retrospective study, the VISX Star S2 excimer laser was used to create a peripheral annular ablation profile to correct spherical hyperopia in 23 eyes of 16 consecutive patients. Attempted corrections ranged from +0.50 diopter (D) to +4.25 D with 0 to 1.00 D of astigmatism. The same laser was used to create a central ablation profile to correct spherical myopia in 25 eyes of 17 consecutive patients. Attempted corrections ranged from -2.25 to -6.50 D with 0 to 1.00 D of astigmatism. The absolute change in refractive astigmatism was calculated by taking the difference in magnitudes of astigmatism before and after laser treatment without regard to axis. Axis and magnitude of SIA were analyzed by vector differences. Magnitudes were compared using the Student t test, and axial shifts were compared using the chi-square test. All patients were followed for a minimum of 6 months. RESULTS: The mean changes in absolute astigmatism were 0.29 +/- 0.28 D at 3 months and 0.34 +/- 0.29 D at 6 months after hyperopic PRK and 0.40 +/- 0.35 D at 3 months and 0.39 +/- 0.36 D at 6 months after myopic PRK. The mean vectoral magnitudes were 0.49 +/- 0.29 at 3 months and 0.52 +/- 0.25 at 6 months after hyperopic PRK and 0.48 +/- 0.39 at 3 months and 0.44 +/- 0.38 at 6 months after myopic PRK. The mean values for SIA (the centroid) were 0.10 +/- 0.57 D x 113 degrees at 3 months and 0.15 +/- 0.57 D x 131 degrees at 6 months after hyperopic PRK and 0.04 +/- 0.63 D x 160 degrees at 3 months and 0.08 +/- 0.58 D x 171 degrees at 6 months after myopic PRK. There was no statistically significant difference between the 2 groups in vectoral axis or magnitude of SIA. CONCLUSION: Surgically induced astigmatism after hyperopic PRK was comparable to astigmatism induced by myopic PRK. A peripheral annular ablation for hyperopic correction, similar to a central ablation in myopic PRK, did not appear to result in uneven corneal healing causing astigmatism.     

Corneal haze among blue eyes and brown eyes after photorefractive keratectomy

BACKGROUND: To compare the incidence and severity of corneal haze after photorefractive keratectomy (PRK) among white patients with blue eyes and Saudi patients with brown eyes. DESIGN: Retrospective, nonrandomized, comparative trial. PARTICIPANTS: A total of 150 patients (71 females and 79 males) were included in this study. Two hundred sixty-six eyes of 150 patients were subjected to PRK. One hundred blue eyes of 50 white patients and 166 brown eyes of 100 Saudi patients were included in this study. METHODS: Two hundred sixty-six eyes of 150 patients were subjected to PRK with the Chiron Technolas Keracor 117C for the correction of myopia and astigmatism. MAIN OUTCOME MEASURES: All patients had complete ophthalmologic examinations, visual acuity testing, intraocular pressure, pachymetry, corneal haze assessment (0-4+), and computerized corneal topography. RESULTS: There were 266 eyes of 150 patients with 100 blue irides and 166 brown irides. The spherical equivalent was -0.50 diopter (D) to -8.75 D. The mean postoperative spherical equivalent at 6 months was -0.063 D (standard deviation [SD], +/-0.595) in blue eyes compared to -0.28 D (SD, +/-0.683) in brown eyes (P = 0.006). Ninety-five (95%) of 100 of the blue eyes achieved +/- 1 D of attempted correction compared to 148 (89.2%) of the 166 brown eyes. All patients with blue eyes had a visual acuity of 20/30 or better compared to 153 (92.2%) of the 166 brown eyes (P = 0.009). Forty-eight (18.04%) eyes had minimal to mild haze, 3 (1.12%) eyes had moderate haze, and 2 (0.75%) eyes had severe haze. The incidence of corneal haze among brown eyes was 48 (28.9%) of 166 eyes compared to 5 (5%) of 100 in blue eyes (P < 0.001). The difference remained significant after adjustment for age and gender with a P value of 0.0283. The relative risk for developing haze in brown eyes was found to be 7.72. CONCLUSION: The incidence of corneal haze after PRK was significantly higher among Saudi patients with brown irides than among white patients with blue irides. This suggests that racial factors may play a role in the development of corneal haze.     

Corneal haze after mechanical debridement for overcorrection after myopic photorefractive keratectomy

A 47-year-old man had photorefractive keratectomy (PRK) to correct myopia. Three months after surgery he was slightly overcorrected with +1.25–0.5/170°. He then suffered a gout attack and showed a refraction of +2.5–0.5/4° which decreased to +1.75–0.5°. To reduce this permanent overcorrection we performed mechanical debridement of the corneal epithelium. the patient had haze grade 2–3 after 2 weeks and haze grade 0–1 some 4 month later. The refraction was +1–0.5/25°. This case report indicates that mechanical debridement is able to reduce overcorrection after PRK and bears a risk of haze formation comparable to that associated with PRK.     

Intraocular pressure trend following myopic photorefractive keratectomy

International Ophthalmology - To evaluate the intraocular pressure (IOP) trend and risk factors for IOP rise after myopic photorefractive keratectomy (PRK). One eye of each patient undergone PRK...     

Evaluation of photorefractive keratectomy retreatments after regressed myopic laser in situ keratomileusis

PURPOSE: To evaluate the results of photorefractive keratectomy (PRK) enhancements in eyes previously treated by myopic laser in situ keratomileusis (LASIK) showing an undercorrection due to either a refractive regression or a primary undercorrection, when an in-the-bed enhancement was not advisable because of residual stromal thickness limitations. DESIGN: Noncomparative, prospective, interventional case series. PARTICIPANTS: Seventeen eyes of 17 patients previously treated by LASIK for a spherical equivalent (SE) correction of -8.125 to -12.50 diopters (D; mean, -9.45 +/- 1.01 D), that after a follow-up of 6 to 14 months ended up with a refraction of -1.50 to -3.75 D (SE; mean, -2.48 +/- 0.74 D). Intended flap thickness was 160 microm for all eyes. In all cases, the residual stromal bed under the flap was considered too thin (255-305 microm) to allow an in-the-bed enhancement without exceeding an assumed safety thickness limit (250 microm). INTERVENTION: Eyes were treated by PRK at least 6 months after LASIK. The PRK ablation parameters (diameter, attempted correction) were selected to avoid theoretical flap perforation. The deepest ablation was 60 microm, for a -3.75-D correction. We used a Bausch & Lomb 217 C excimer laser (Bausch & Lomb, Rochester, New York). MAIN OUTCOME MEASURES: Refraction, uncorrected and best-corrected visual acuity (BCVA), slit-lamp evidence of corneal opacity or other visible complications, and corneal topography. RESULTS: Although the initial postoperative period was characterized by very satisfactory refractive results (mean SE error at 1 month, -0.04 +/- 0.37 D; range, +0.75 to -0.625 D), during follow-up, a dense haze (grade 3 and 4) developed in 14 eyes (82.3%) that induced a further myopic regression (SE, -1.725 to -5.50 D; mean, -3.11 D) and BCVA loss (two to six lines). These 14 eyes underwent a further surgical treatment to remove the severe haze at 3 to 10 months after PRK. CONCLUSIONS: Based on these results, we strongly advise against PRK as a possible option to correct eyes previously treated by myopic LASIK that resulted in an undercorrection.     

Wavefront-guided photorefractive keratectomy for myopia and myopic astigmatism

PURPOSE: To evaluate the results of wavefront-supported customized ablation (WASCA) in eyes treated with photorefractive keratectomy (PRK) to correct spherical myopia and myopic astigmatism. METHODS: One-hundred fifty eyes of 104 patients (mean age 33.4 +/- 4.4 years) were included in the study. An Asclepion Shack-Hartmann wavefront aberrometer was used to assess lower and higher order refractive aberrations of eyes, and customized PRK treatments were carried out using the Asclepion-Meditec MEL 70 G-Scan excimer laser. Follow-up time was 6 months. RESULTS: The mean preoperative spherical equivalent refraction was -4.02 +/- -1.04 D, and mean uncorrected visual acuity (UCVA) was 0.06 +/- 0.02. Postoperatively, mean UCVA was 1.04 (better than 20/20), mean best spectacle-corrected visual acuity was 1.22 (20/16), and average spherical equivalent refraction was -0.12 D; 98.6% (148 of 150 eyes) were within +/-0.50 D of intended refraction, and 100% were within +/-1.00 D. Concerning safety, in 71.1% of eyes (107 of 150) BSCVA was the same as preoperatively, and in 8.2% (11 of 150) it increased by two or more Snellen lines. None of the eyes lost two or more lines of BSCVA. The root mean square value for higher order aberrations increased 1.4 times following PRK. CONCLUSIONS: WASCA-guided PRK was efficacious, safe and predictable; BSCVA may be improved by the WASCA method compared to results achievable with a traditional PRK technique, in spite of an increase in the root mean square value for higher-order aberrations.