Photorefractive keratectomy for low-to-moderate myopia and astigmatism with a small-beam, tracker-directed excimer laser.

OBJECTIVE: To assess the safety and effectiveness of the Autonomous Technologies Corporation LADARVision excimer laser system for photorefractive keratectomy correction of myopia and astigmatism. DESIGN: A multicenter, prospective, noncomparative case series. PARTICIPANTS: The cohort consisted of 467 eyes corrected for spherical myopia and 211 eyes corrected for myopia with astigmatism. INTERVENTION: Treatments were performed at six sites in the United States using a 6-mm ablation zone for spherical myopes and a 5.5-mm zone with a 1.0-mm blend for astigmats. MAIN OUTCOME MEASURES: Visual acuity, subjective refraction, corneal haze, intraocular pressure, complications, adverse reactions, patient satisfaction, and corneal endothelial changes. RESULTS: Twelve-month follow-up was available on 414 spherical eyes and 175 astigmatic eyes. The results for spherical eyes with correction between -1 and -5.99 diopters (D) were: uncorrected visual acuity (UCVA) of 20/40 or better achieved by 98.1%, 20/20 or better by 72%, 1.8% lost 2 lines and 0.3% lost greater than 2 lines of best spectacle-corrected visual acuity (BSCVA); 76.4% were within 0.50 D of the target correction and 94.4% were within 1.00 D. The results for myopia with astigmatism with spherical equivalent correction between -1 and -5.99 D were: UCVA of 20/40 or better in 97.4%, 20/20 or better in 61.7%, 2.5% lost 2 lines and no eyes lost greater than 2 lines BSCVA; 73.9% were within 0.50 D of the target correction and 95% were within 1.00 D. For spherical myopes combined with myopic astigmats corrected for 6 to 10 D, results were: UCVA of 20/40 or better in 93.4%, 20/20 or better in 61.2%, 2.3% lost 2 lines and no eyes lost greater than 2 lines of BSCVA; 67.2% were within 0.50 D of the desired correction and 87.8% were within 1.00 D. Refractive stability was achieved between 3 and 6 months for the spherical and astigmatic groups. No eyes had corneal haze graded as moderate or greater, and there was no significant decrease in endothelial cell density. CONCLUSIONS: Patients treated for 1 to 10 D of spherical equivalent myopia, with or without astigmatism, showed early refractive stability, excellent UCVA, no significant loss of BSCVA, no loss of endothelial cell density, and very low levels of corneal haze to 12 months after surgery.

Five and three year follow-up of photorefractive keratectomy for myopia of -1 to -6 diopters.

BACKGROUND: To report the 5 and 3 year results of photorefractive keratectomy for -1 to -6 D of myopia and less than 1.50 D astigmatism. METHODS: All eyes were treated with a VISX 20/20 excimer laser with an ablation diameter of 5 mm. Our initial series of 133 eyes were treated in four groups: IIA, IIB, III and III No Nitrogen and reported on previously with follow-up from 6 to 36 months. The present report extends the observation period to 3 and 5 years for 114 eyes. RESULTS: Groups IIA and IIB were followed for 5 years and Groups III and III No Nitrogen for 3 years. Group IIA achieved 77% (10 of 13 eyes) +/-1.00 D (54% within +/-0.50 D) of emmetropia with stability from 6 months and 54% (seven of 13 eyes) had visual acuity of 20/20 or better. In Group IIB, 35% (six of 17 eyes) were +/-1.00 D (18% within +/-0.50 D) of emmetropia and stable from 18 months. Two of 17 eyes (12%) had 20/20 or better visual acuity. Group III had 76% (42 of 55 eyes) within +/-1.00 D (51% within +/-0.50 D) of emmetropia with stability after 12 months; 60% (33 of 55 eyes) had 20/20 or better visual acuity. Group III No Nitrogen had 73% (11 of 15 eyes) within +/-1.00 D (60% within +/-0.50 D) of emmetropia and were stable after 6 months; 47% (seven of 15 eyes) had 20/20 or better visual acuity. There was no hyperopic refractive shift. No correlation was found between the percent of correction achieved and preoperative amount of myopia, age, or sex. CONCLUSION: Refractive stability was achieved from 6 to 12 months in most eyes; a few required 18 months to stabilize. Groups IIA and III continued to be stable; Groups HB and III No Nitrogen showed mild regression that was not statistically significant.

Ablation zone centration after photorefractive keratectomy and its effect on visual outcome.

PURPOSE: To determine the relation between ablation zone decentration, measured by corneal topography, and visual and refractive outcome, contrast sensitivity, glare, and subjective reports of halos after photorefractive keratectomy (PRK). SETTING: Eye Foundation, University of Missouri-Kansas City School of Medicine. METHODS: This study comprised 70 eyes of 70 patients enrolled into Phase III of the clinical investigation of the VISX 20/20 excimer laser for the correction by PRK of 1.00 to 6.00 diopters of pre-existing sphere. All patients were treated with 5.0 mm ablation zones. Preoperative and postoperative corneal topography in 67 eyes was done using the EyeSys system. Ablation zone decentration was measured relative to the pupillary center at all postoperative visits as determined from the difference or change map. RESULTS: Mean distance between the ablation zone center and the pupillary center was 0.62 mm +/- 0.34 (SD) (range 0.07 to 1.67 mm). Twenty seven of 66 patients with corneal topography (40.9%) had decentrations less than 0.5 mm; decentrations in 6 eyes (9.1%) were 1.0 mm or more from the pupillary center. No correlation was observed between the magnitude of decentration and 1 year postoperative best spectacle-corrected acuity (r = -.04, P = .76), uncorrected acuity (r = -.03, P = .84), or spherical equivalent (r = -.07, P = .59); preoperative uncorrected acuity (r = .04, P = .73) or spherical equivalent (r = -.02, P = .90); or reduction in spherical equivalent (r = .02, P = .89). The magnitude of decentration was correlated with preoperative spectacle-corrected acuity (r = -.37, P = .002). There was no difference in contrast sensitivity, glare, or halos between the cases with less than 0.5 mm of decentration and those with 0.5 mm or more of decentration. CONCLUSIONS: The degree of ablation zone decentration did not affect postoperative Snellen visual acuity or contrast sensitivity.

Excimer retreatment for myopic photorefractive keratectomy failures. Six- to 18-month follow-up.

PURPOSE: To study the results of retreatment after myopic photorefractive keratectomy in 22 patients. Five patients showed regression and 17 showed undercorrection combined with regression. The follow-up was 6 to 18 months. METHODS: A laser was used with a fluence of 160 mJ/cm2 at a frequency of 5 Hz. The same nomogram used for the initial treatment was used for the retreatment. No nitrogen purge was used. Fluorometholone 0.1% four times daily tapered over 4 months was applied postoperatively except in five patients. RESULTS: There was no untoward effect in any patient who had retreatment. The mean preoperative spherical equivalent before retreatment was -2.61 +/- 1.62 diopters (D) (range, -1.00 to -6.63 D). After 1 year, the mean spherical equivalent was -0.84 +/- 1.22 D (range, 0.00 to -4.88 D) and at 18 months it was -1.31 +/-1.60 D (range, 0.00 to -5.13 D). Spherical equivalent was +/- D in 82% of patients at 1 year and in 67% at 18 months. Uncorrected visual acuity was 20/40 or better at 1 year in 77% of patients and 20/20 or better in 55%; at 18 months, it was 20/40 or better in 67%. CONCLUSION: Retreatment may be considered for undercorrection and/or regression in photorefractive keratectomy. No complications were observed, and there is appreciable improvement in the final results. The refraction 6 months after retreatment is stable with no statistically significant change from 6 to 12 months (Student's t=0.51; P=0.62) and 6 to 18 months (Student's t=1.0l; P=0.33).

Two-zone excimer photorefractive keratectomy for moderate myopia. Six- to 18-month follow-up.

PURPOSE: To study the results of the two-zone photorefractive keratectomy (PRK) in 35 eyes of 27 patients with moderate myopia of 6 to 8 diopters (D) over 6 to 18 months. METHODS: An excimer laser was used with a fluence of 160 mJ/cm2 at a frequency of 5 Hz. The ablation was performed with two zones (6 and 5 mm). All patients received topical steroid (0.1 fluorometholone) tapered over 4 months. RESULTS: There were no significant untoward effects in any patient. There were minimal changes in contrast sensitivity, brightness acuity, and astigmatism. Uncorrected visual acuity of 20/40 or better was obtained in 77% of patients at 6 months, in 73% at 12 months, and in 71% at 18 months. A refraction of +/-1.0 diopter was obtained in 69% at 6 months, in 65% at 12 months, and in 71% at 18 months. There is no statistically significant difference at 6, 12, and 18 months in both visual acuity and refraction. CONCLUSIONS: Two-zone PRK in moderate myopia is safe and reasonably effective. The results are stable from 6 to 18 months.

Corneal endothelial status 12 to 55 months after excimer laser photorefractive keratectomy.

PURPOSE: To investigate the long-term effect (range, 12-55 months) of photorefractive keratectomy (PRK) on the human corneal endothelium. METHODS: Specular microscopy of the central corneal endothelium was performed on 106 patients who underwent PRK to correct myopia. The duration of follow-up varied from 12 to 55 months (mean, 33 months; median, 37 months). Patients were divided in two groups: group 1 included 32 patients (35 treated eyes) with preoperative and postoperative central endothelial images; group 2 included 26 patients from group 1 and 74 additional patients with postoperative central endothelial images of the treated and untreated fellow eyes. RESULTS: In group 1, preoperative and postoperative values were as follows: mean cell density (+/- standard deviation), 2950 +/- 329 cells/mm2 and 2907 +/- 337 cells/mm2, respectively (P = 0.43); polymegathism index, 0.29 +/- 0.06 and 0.28 +/- 0.05, respectively (P = 0.38); pleomorphism index, 65.8% +/- 5.6% and 64.2% +/- 5.6%, respectively (P = 0.22); figure coefficient index, 0.86 +/- 0.05 and 0.87 +/- 0.02, respectively (P = 0.20). In group 2, postoperative values of the treated and untreated eyes were as follows: mean cell density, 2912 +/- 363 cells/mm2 and 2922 +/- 434 cells/mm2, respectively (P = 0.86); polymegathism index, 0.28 +/- 0.05 and 0.30 +/- 0.08, respectively (P = 0.04); pleomorphism index, 64.93% +/- 7.49% and 64.07% +/- 8.31%, respectively (P = 0.45); figure coefficient index, 0.88 +/- 0.03 and 0.88 +/- 0.03, respectively (P = 0.79). CONCLUSIONS: Photorefractive keratectomy caused no damage to the central corneal endothelium. Polymegathism differences in treated and untreated eyes could be attributed to modifications in corneal metabolism or to a yet unknown mechanism.

Excimer photorefractive keratectomy for myopia.

PURPOSE: To study the safety, effectiveness, predictability, and stability of excimer laser photorefractive keratectomy (PRK) in 133 normally sighted eyes. METHODS: An excimer laser was used with a fluence of 160 mJ/cm2 at a frequency of 5 Hz and an ablation zone of 5.0 mm. The effects of nitrogen purge at surgery and postoperative steroids were evaluated. RESULTS: No significant complications occurred in any patient. After an initial over-correction, the refraction stabilized. The average results obtained at 6 months were maintained on successive examinations to 36 months. Analysis of their visual acuity in groups IIA, IIB, and III indicates that results at 6 months are predictive of final results at 1 to 3 years (P < 0.0001; r > 0.9). In myopia (1.00-6.00 diopters [D]) treated with the excimer laser, there was a trend toward improvement in results over the course of the study. In 60% in group IIA, 58% in group IIB, 71% in group III, and 88% in group III no nitrogen (no N2), +/- 1 D was obtained. For 20/40 or better uncorrected visual acuity, the outcome was 70% for group IIA, 67% for group IIB, 75% for group III, and 100% for group III no N2. Significant improvement was noted without nitrogen purge. No significant improvement was observed from steroid treatment as used. CONCLUSION: In reducing myopia, PRK appears to be safe and effective. The results obtained are reasonably predictable and stable after 6 months. As more refinements are introduced, this procedure could become one of the most promising in refractive surgery.

Climatic droplet keratopathy with corneal amyloidosis.

Climatic droplet keratopathy (CDK) is a degenerative disease of the cornea, highly prevalent in Saudi Arabia. It is characterized by aggregates of small, golden-yellow globules that accumulate in the subepithelial layers, Bowman's layer, and the superficial stroma of the cornea. The authors report on 22 patients (40 eyes) with CDK and lattice lines in the cornea. The condition occurred late in life (mean age, 67 years). It was bilateral in 82% of patients, with no family history of lattice dystrophy or systemic amyloidosis. These lines were found in all layers of the stroma. Results of histopathologic and electron microscopic examination of the lattice lines confirmed the presence of amyloid. Results of immunohistochemical examination showed evidence of deposition of AP protein. The cause of these deposits in the cornea is not known, but the authors speculate that environmental factors causing CDK also may play a role in the deposition of protein AP in the cornea. The contribution of trachoma to the degenerative changes in the cornea and secondary amyloidosis could not be ruled out, as all patients had inactive trachoma. Climatic droplet keratopathy with corneal amyloidosis, therefore, represents a form of "lattice degeneration" of the cornea.

Cryotherapy of herpes simplex keratitis.

Twenty-one cases of epithelial herpetic keratitis were treated with cryotherapy and 14 cases were treated with Iodoxouridine (IDU). Cryotherapy was found statistically superior to IDU. The average healing time was 2.4 days for cryotherapy and 6.2 days for IDU. The advantages of cryotherapy are emphasized.

Expulsive hemorrhage: report of five cases.

Five cases of expulsive hemorrhage occurring over a period of one year were reviewed. Two cases occurred during a trabeculectomy procedure. There appear to be multiple factors playing a role in the etiology of expulsive hemorrhage. There was not a single common factor among these 5 cases, except for the conjectural presence of some kind of vascular disease. However, there were some important factors that may have played a role such as glaucoma, hypertension, vascular disease, and general anesthesia (and sudden decompression of the globe).

Outcome of traumatic hyphema.

One hundred and twenty-seven cases of traumatic hyphema are reviewed and discussed according to a definite system of grading. Grade iii hyphemas have definitely a poorer prognosis than Grade ii and Grade i hyphemas. Rebleeding occurs more frequently when there is a delay in treatment but does not appear to affect the outcome of a traumatic hyphema. Blood staining of the cornea could be avoided by an adequate treatment started immediately after the trauma, thus decreasing the percentage of blindness following a traumatic hyphema.

Eye manifestations in acrodermatitis enteropathica.

A case of acrodermatitis enteropathica is presented that is the first to manifest punctal stenosis, the fourth to show corneal changes, and the sixth to survive into adulthood.