David R. Hardten

CORNEOSCLERAL MELT AFTER PTERYGIUM SURGERY USING A SINGLE INTRAOPERATIVE APPLICATION OF MITOMYCIN-C

A 59-year-old man underwent pterygium excision with intraoperative application of 0.2 mg/ml (0.02%) mitomycin-C placed on the scleral bed for 3 min. A sliding conjunctival flap was used to cover the exposed limbus and sclera. Five weeks after the original surgery, the patient had mild trauma and noted decreased vision. At that time, it was noted that he had a corneoscleral melt with perforation. The patient was managed with a lamellar transplant in this area. Intraoperative single-dose application of topical mitomycin-C can be associated with serious complications. This case occurred despite the fact that this patient received the lowest dose used in a series of 25 eyes using the same technique without any other complications. Although topical mitomycin-C is effective as an adjunct to pterygium surgery and may reduce recurrence, the safety and efficacy of various concentrations and dosing schedules need further definition.

Excimer Laser Photorefractive Keratectomy in High Myopia: A Multicenter Study

Excimer photorefractive keratectomy was performed at three centers on 16 highly myopic eyes (8 diopters [D] or more) and followed up for 6 months. Ablation depths ranged from 137 to 230 microns. The preoperative spherical equivalent of myopia ranged from -8.62 D to -14.50 D (mean +/- SD, -11.57 +/- 1.62 D). Six months after surgery, the mean refraction (spherical equivalent) was -0.90 +/- 2.13 D. Eleven of 16 eyes achieved refractions within 2 D of that attempted. All eight patients at one site were treated with a maximum-beam diameter of 6.0 mm and were corrected to within 2 D of that attempted, and all were 20/40 or better uncorrected. Three of eight eyes at the other two sites were treated with a 5.5- or 5.6-mm maximum-beam diameter, which achieved corrections within 2 D of that attempted. The epithelium healed within 3 to 4 days, and there were no erosions. Mild subepithelial reticular haze, similar to that seen with excimer photorefractive keratectomy for lower myopia, was seen in all patients, with two patients experiencing more significant corneal haze. This peaked at 3 to 6 weeks and then gradually diminished. All but two patients had a return of their best corrected preoperative visual acuity to within one Snellen line at 6 months. This preliminary study shows excimer photorefractive keratectomy to be a promising surgical treatment for patients with higher myopia.

193-nm Excimer Photorefractive Keratectomy in High Myopia

PURPOSE To evaluate the refractive results of 193-nm excimer laser photorefractive keratectomy (PRK) performed on 48 highly myopic eyes in a multicenter study. METHODS A Visx 2015 or 2000 argon-fluoride excimer laser and a single-zone ablation technique were used. Postoperatively, eyes were treated with topical fluoromethalone for up to 5 months. Most eyes were treated with a 6.0- to 6.2-mm beam diameter after undercorrections and increased regression were noted with a 5.5-mm beam in earlier studies. Forty-eight eyes were treated for myopia, which was between -8.0 and -15.25 diopters (D) (spherical equivalent). The mean preoperative refraction was -11.2 D. Retreatment was performed after 6 to 16 months on 11 eyes for undercorrection. All eyes not retreated were followed for at least 12 months. RESULTS At 6 months, follow-up was available on 47 eyes. Of these eyes, 40% and 64% achieved corrections within 1 and 2 D of attempted correction, respectively. At 1 year, 60% of eyes attained 20/40 visual acuity or better uncorrected. Eleven patients (23%) were retreated between 6 to 16 months for undercorrection and/or regression. After retreatment, 47% and 81% of eyes achieved corrections within 1 and 2 D of attempted correction, respectively. At 1 year, 15% of eyes lost two lines of best-corrected visual acuity, and no eyes lost more than two lines. There was slightly more corneal haze seen in this group compared with the haze seen in patients undergoing PRK for low and moderate myopia. CONCLUSIONS These data show that excimer PRK can correct high amounts of myopia with reasonable stability after 6 months. Excimer PRK is an effective surgical treatment of severe myopia, but long-term follow-up is still needed to assess the stability of its effect.

Cataract surgery in patients with prior refractive surgery.

As the number and types of keratorefractive procedures increase and as the baby boomer population moves into the “cataractous decades,” the number of patients requiring cataract surgery following refractive surgery grows larger each year. While technological advances in surgical instrumentation and intraocular lens (IOL) design allow us to perform cleaner, faster, and more reliable cataract extractions, the ultimate postoperative refraction depends primarily on calculations performed before surgery. Third-generation IOL formulas (eg, Haigis, Hoffer Q, Holladay 2, or SRK/T) provide outstanding accuracy when used for eyes with physiologic, prolate corneas. In addition, most instruments used today for measuring corneal curvature and power were designed before the era of refractive surgery. These formulas and instruments make assumptions about the anatomy and refractive properties of the cornea that are no longer valid following most keratorefractive procedures. These breakdowns in IOL calculation often result in a “refractive surprise” after cataract surgery, which may require subsequent surgical correction. This article examines recent publications of modeling studies of various methods for estimating effective K values for IOL calculation, cataract surgery case series following refractive surgery, new corneal topography technologies and methods for correcting “refractive surprises” postoperatively.

Results One Year After Using the 193-nm Excimer Laser for Photorefractive Keratectomy in Mild to Moderate Myopia

As part of a clinical trial, photorefractive keratectomy using the VISX 2015 193-nm excimer laser was performed on 91 healthy eyes of 91 patients. Preoperative refractive errors (spherical equivalent) ranged from -1.00 to -7.50 diopters (mean, -4.16 +/- 1.41 diopters). No patient had more than 1 diopter of refractive astigmatism. Six months postoperatively, the average residual refractive error was +0.09 +/- 0.63 diopters (range, -2.13 to +1.63 diopters). Correction within 1 diopter of that attempted was attained in 85 eyes (93%). Uncorrected visual acuity of 20/40 or better was attained in 86 eyes (95%) and was 20/25 or better in 67 eyes (74%). At one year, follow-up information was available on 85 eyes of 85 patients. The average residual refractive error was -0.15 +/- 0.65 diopters (range, -2.50 to +1.63 diopters). Correction within 1 diopter of that attempted was attained in 85 eyes (93%). Uncorrected visual acuity was 20/40 or better in 83 eyes (98%) and was 20/25 or better in 68 eyes (80%). One patient lost three lines of best-corrected visual acuity because of corneal haze, dropping from 20/15 to 20/30, whereas all other patients returned to best-corrected visual acuity within one line of their preoperative best-corrected visual acuity. Photorefractive keratectomy with the 193-nm excimer laser appears to be a useful treatment modality for the reduction of mild to moderate myopia.

Fibrin glue for the prevention of epithelial ingrowth after laser in situ keratomileusis

We present 3 cases of recurrent epithelial ingrowth following laser in situ keratomileusis. All patients consented to flap lifting, epithelial ingrowth removal, and placement of fibrin glue (Tisseel(R) VH, Baxter) at the flap edges. Two of 3 eyes had no evidence of recurrent epithelial ingrowth within a relatively short follow-up. One eye that also had had radial keratotomy had a small nest of stable epithelial cells that had not progressed. Fibrin glue may be a useful adjunct to prevent recurrent epithelial ingrowth. There were no complications associated with its use.

Concentrations of levofloxacin, ofloxacin, and ciprofloxacin in human corneal stromal tissue and aqueous humor after topical administration.

Objective: To evaluate the penetration of commercially available levofloxacin 0.5%, ofloxacin 0.3%, and ciprofloxacin 0.3% topical ophthalmic solutions in human corneal stromal and aqueous humor tissues. Methods: A total of 67 patients scheduled to undergo penetrating keratoplasty for treatment of stromal scar or dystrophy, keratoconus, pellucid marginal degeneration, or endothelial disease were enrolled in this prospective, double-blind, 3-center study. To be considered for inclusion, patients had to have an intact corneal epithelium and minimal or no corneal edema (pachymetry < 650 μm). After informed consent was obtained, patients were randomized to receive 1 drop of levofloxacin 0.5%, ofloxacin 0.3%, or ciprofloxacin 0.3% topical ophthalmic solution at approximately 15 and 10 minutes before surgery. Approximately 0.1 mL of aqueous fluid was aspirated by paracentesis through the trephination wound at the onset of surgery, followed by excision of the affected cornea and removal of its epithelium. Specimens were stored frozen at −70°C until assayed by high-performance liquid chromatography. Results: All 3 fluoroquinolones were well tolerated. A total of 65 corneas and 59 aqueous fluid samples were obtained and assayed. The mean ± standard deviation corneal concentrations of ciprofloxacin, ofloxacin, and levofloxacin following a 2-drop administration were 9.92 ± 10.99 μg/g (n = 18), 10.77 ± 5.90 μg/g (n = 23), and 18.23 ± 20.51 μg/g (n = 24), respectively. Although corneal stromal levels were highest in the levofloxacin group, the high degree of interpatient variability prevented demonstration of statistically significant differences when compared with ofloxacin (P = 0.377). In contrast, levofloxacin concentrations were approximately twice as high as ciprofloxacin, and this difference reached statistical significance (P = 0.014). The corresponding aqueous humor concentrations of ciprofloxacin, ofloxacin, and levofloxacin were 0.135 ± 0.231 μg/mL (n = 15), 0.135 ± 0.111 μg/mL (n = 20), and 0.372 ± 0.546 μg/mL (n = 24, P < 0.001 versus ciprofloxacin and ofloxacin). Conclusion: The topical administration of all 3 agents was well tolerated in patients undergoing penetrating keratoplasty. Two drops of levofloxacin 0.5% solution results in a 1.7- to 2.7-fold greater penetration into human corneal stromal and aqueous humor tissues than ofloxacin 0.3% or ciprofloxacin 0.3%. The mean intracorneal concentrations of all three agents following 2 drops exceeds the MIC90 for the majority of pathogens causing bacterial keratitis. Topical levofloxacin appears to offer pharmacokinetic and pharmacodynamic advantages over ofloxacin and ciprofloxacin in terms of enhanced transcorneal penetration; however, clinical comparative trials are needed to confirm these relative advantages.

Twice-Daily, Preservative-Free Ketorolac 0.45% for Treatment of Inflammation and Pain After Cataract Surgery

PURPOSE To evaluate the efficacy and safety of twice-daily, preservative-free ketorolac 0.45% (Acuvail; Allergan, Inc, Irvine, California, USA) administration for treatment of inflammation and pain after cataract surgery. DESIGN Prospective, randomized trial. METHODS Two multicenter, double-masked studies randomized 511 cataract surgery patients (2:1) to receive twice-daily ketorolac 0.45% or vehicle in the operative eye for 16 days, beginning 1 day before surgery. The primary efficacy end point was the percentage of patients with a summed ocular inflammation score of 0 for anterior chamber cell and flare on postoperative day 14. The main secondary efficacy end point was the percentage of patients with no pain on postoperative day 1. RESULTS On day 14, 52.5% of ketorolac patients and 26.5% of vehicle patients had an summed ocular inflammation score of 0 (P < .001). On day 1, 72.4% of ketorolac patients and 39.7% of vehicle patients had a pain score of 0 (P < .001). Median time to pain resolution was 1 day in the ketorolac group and 2 days in the vehicle group (P < .001). The percentage of ketorolac and vehicle patients who had a +3-line or more improvement in best-corrected visual acuity from baseline was 60.5% versus 44.0% on day 14 (P = .002). Overall, adverse events were more prevalent in the vehicle group than in the ketorolac group (48.5% vs 35.2%; P = .004). Burning or stinging (per a composite Medical Dictionary for Regulatory Activities) was reported by 1.5% of ketorolac patients and 0.6% of vehicle patients. CONCLUSIONS Twice-daily ketorolac 0.45% was well tolerated and effectively treated inflammation and pain following cataract surgery.

To lift or recut: Changing trends in LASIK enhancement

Purpose: To report serious complications caused by recutting laser in situ keratomileusis (LASIK) flaps for enhancement and reconsider the current preferred method of LASIK enhancement. Setting: Multiple surgeon practices. Methods: This retrospective noncomparative nonconsecutive case series comprised LASIK patients in the private practices of 9 experienced refractive surgeons and those reported in a survey of refractive surgeons. Case histories, refractions, corneal topographies, slitlamp photographs, and measurements of uncorrected and best corrected (BCVA) visual acuity after recutting LASIK flaps were collected. Surveys of refractive surgeons and an analysis of changing practice trends among the authors and these surgeons were assessed. Results: In 12 cases, significant loss of BCVA and subjective visual difficulties resulted from recutting LASIK flaps. Most surveyed surgeons had changed their practice from recutting to lifting flaps even 9 to 10 years postoperatively with good results. Conclusion: Recutting flaps for enhancement should be avoided unless other alternatives are unavailable.

A multicenter study to map genes for Fuchs endothelial corneal dystrophy: Baseline characteristics and heritability

Purpose: To describe the methods for family and case–control recruitment for a multicenter genetic and associated heritability analyses of Fuchs endothelial corneal dystrophy (FECD). Methods: Twenty-nine enrolling sites with 62 trained investigators and coordinators gathered individual and family information, graded the phenotype, and collected blood and/or saliva for genetic analysis on all individuals with and without FECD. The degree of FECD was assessed in a 0 to 6 semiquantitative scale using standardized clinical methods with pathological verification of FECD on at least 1 member of each family. Central corneal thickness was measured by ultrasonic pachymetry. Results: Three hundred twenty-two families with 330 affected sibling pairs with FECD were enrolled and included a total of 650 sibling pairs of all disease grades. Using the entire 7-step FECD grading scale or a dichotomous definition of severe disease, heritability was assessed in families via sib–sib correlations. Both binary indicators of severe disease and semiquantitative measures of disease severity were significantly heritable, with heritability estimates of 30% for severe disease, 37% to 39% for FECD score, and 47% for central corneal thickness. Conclusions: Genetic risk factors have a strong role in the severity of the FECD phenotype and corneal thickness. Genotyping this cohort with high-density genetic markers followed by appropriate statistical analyses should lead to novel loci for disease susceptibility.