bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-term Effects of Radial Keratotomy on the Corneal Endothelium
Authors: MacRae Scott M , Rich Larry F 
Published: April 2021

ABSTRACT
BACKGROUND: The long-term effects of radial keratotomy on the corneal endothelium are not well understood. We evaluated the effects of radial keratotomy on the corneal endothelium on the central and midperipheral corneal endothelium.
METHODS: Anterior radial keratotomy in 25 eyes was performed and patients were followed for a duration of 4 to 10 years after surgery. Eleven non- contact lens wearing control eyes did not have surgery and were followed for the same period. Morphometric analysis of specular microscopic images was performed with regard to cell density, percent hexagonality, and coefficient of variation.
RESULTS: Mean corneal endothelial cell loss rates were 0.4% per year in the radial keratotomy group and 0.9% in the untreated control group over the study duration (mean 7 yr). Morphometric analysis of the cells failed to show a significant change in hexagonality and coefficient of variation. Evaluation of the midperipheral corneal cell counts demonstrated a 1% per year cell loss rate. The cell loss rates in radial keratotomy patients followed over this period were consistent with that noted for normal aging (0.5 to 2.5% per year).
CONCLUSION: Radial keratotomy does not cause accelerated endothelial cell loss over 4 to 10 years. [J Refract Surg 1998;14:49-52]
Therapeutic Alloplastic Laser in situ Keratomileusis for Myopia
Authors: Maldonado-Bas Arturo , Pulido-Garcia Ruben 
Published: April 2021

ABSTRACT
BACKGROUND: A new technique, therapeutic alloplastic laser in situ keratomileusis to correct high myopia, is introduced.
METHODS: Therapeutic alloplastic laser in situ keratomileusis consists of neutral homoplastic epikeratoplasty combined with superficial keratectomy performed with an excimer laser and/or a microkeratome. Indications for the technique are: myopia over 20 diopters (D), eyes with corneal scarring after photorefractive keratectomy (PRK), complications following keratomileusis, radial keratotomy complications with undercorrection, and keratoconus suspect myopic eyes.
RESULTS: In all five eyes we achieved precise corneal lathing with the microkeratome or the excimer laser, and obtained a clear allograft. In all eyes, we maintained or improved the patient's spectacle-corrected visual acuity related to baseline values. We did not induce astigmatism, and corneal thickness was almost unchanged.
CONCLUSIONS: Advantages of therapeutic alloplastic laser in situ keratomileusis are that it provides a Bowman's layer for the cornea following keratectomy, it is possible to lathe ablation diameters larger than 5 mm, it prevents the appearance of corneal haze, and reduces the need for corticosteroid treatment. [J Refract Surg 1998;14:64-69]
Results and Complications of Laser in situ Keratomileusis by Experienced Surgeons
Authors: Davidorf Jonathan M , Zaldivar Roberto , Oscherow Susana 
Published: April 2021

ABSTRACT
PURPOSE: To identify intraoperative and early postoperative adverse events and complications that may be encountered after the laser in-situ keratomileusis (LASIK) learning process.
METHODS: One hundred sixty-nine consecutive eyes of 108 patients who had LASIK by a surgeon experienced in LASIK were studied. All intraoperative and early postoperative adverse events and complications were noted. Patients were examined at 1 day and 1 to 3 months after surgery. Six baseline refractive groups were studied: high myopia with astigmatism (-10.25 to -17.50 D; 18 eyes), moderate myopia with astigmatism (-6.00 to -9.50 D; 31 eyes), low myopia with astigmatism (-0.75 to -5.87 D; 81 eyes), mixed astigmatism (-0.25 to +0.50 D; 6 eyes), low to moderate hyperopia with astigmatism (+1.00 to +3.75 D; 19 eyes), and high hyperopia with astigmatism (+4.25 to +7.37 D; 12 eyes). Seventy-eight percent (132 eyes) had a primary LASIK procedure; 22% (37 eyes) had LASIK after previous refractive surgery. Primary and secondary LASIK procedures were analyzed together. The Nidek EC-5000 or the Chiron PlanoScan excimer lasers were used.
RESULTS: The most commonly observed adverse intraoperative events were minor corneal bleeding (3%) and thin flap (1%). The most commonly observed postoperative events were punctate epithelial keratopathy (6%) and small epithelial defect 1 day after surgery (5%). The most serious complication occurred in three eyes with preoperative high hyperopia (spherical equivalent refraction greater than +4.00 D) in which corneal topographic abnormalities resulted. At last examination, mean postoperative spherical equivalent refraction was less than +1.00 D in all groups. Spectacle-corrected visual acuity was 20/20 in 70 eyes (41%) and 20/25 or better in 119 eyes (70%). Loss of spectacle-corrected visual acuity of two or more lines occurred in five eyes (3%), three of which had preoperative high hyperopia with abnormal postoperative corneal topography.
CONCLUSION: Our prospective study should help LASIK surgeons gauge their expectations of intraoperative and early postoperative complications. Surgeons should proceed cautiously when treating patients with high hyperopia, because a higher incidence of loss of spectacle-corrected visual acuity may be encountered postoperatively. [J Refract Surg 1998;14:114-122]
Multiple Photorefractive Keratectomy Retreatments for Myopia
Authors: Higa Hugo , Couper Terry , Robinson David I M , Taylor Hugh R 
Published: April 2021

ABSTRACT
PURPOSE: To examine the outcome of multiple photorefractive keratectomy retreatments by the excimer laser on eyes treated for myopia and myopic astigmatism.
METHODS: We present 980 of 1218 (80%) consecutive eyes treated with a VISX 20/20 excimer laser that were available for follow-up. Thirteen eyes of 13 individuals were retreated twice using the same VISX excimer laser because of refractive regression. Epithelium was mechanically removed in the initial treatment and subsequent retreatment of all the eyes. No increased difficulty was noted upon removing the epithelium on subsequent retreatments. The aim in both the initial and subsequent treatments was to correct 100% of the refractive error.
RESULTS: Eyes with higher amounts of myopia and astigmatism were more likely to require multiple retreatments. Seven eyes (54%) attained a spectacle-corrected visual acuity of 20/20 or better. Twelve eyes (92%) attained a spectacle-corrected visual acuity of 20/40 or greater following the second retreatment. The amount of astigmatism corrected was improved in 10 of the 13 eyes with an average improvement of 1.90 D of cylinder. Only one patient experienced a haze score of 3 or more following retreatment.
CONCLUSION: There is a subgroup of patients who require multiple PRK retreatments for myopic regression. A good visual outcome may be obtained with minimal haze. [J Refract Surg 1998;14:123-128]
Effects of Gamma-interferon on Keratocyte-induced Collagen Gel Contraction and Keratocyte Proliferation
Authors: Pakkar Alireza , Rofougaran Roya , Lu Ken , Wee Won R , Isfahani Amir K , McDonnell Peter J 
Published: April 2021

ABSTRACT
PURPOSE: Gamma-interferon has been shown to be an effective immunoregulatory polypeptide that can modulate fibroblastic response. We investigated the effects of gamma-interferon on keratocyte proliferation and keratocyte-induced collagen gel contraction.
METHODS: Gamma-interferon in concentrations of 0.01, 1, 100, and 1000 U/ml of media was added to keratocytes embedded in polymerized type I collagen and the gel area was measured after 5 days with an image analysis system. The rate of keratocyte proliferation within and outside the collagen gel under the influence of gamma-interferon was also investigated.
RESULTS: Keratocyte-induced collagen gel contraction was significantly inhibited at all concentrations above 0.01 U/ml. The keratocyte proliferation was not affected by low and moderate concentrations and was significantly stimulated at concentration of 1000 U/ml.
CONCLUSION: Keratocyte-induced collagen gel contraction is inhibited by gamma-interferon and the mechanism of this effect is not inhibition of keratocyte proliferation by gamma-interferon. [J Refract Surg 1998;14:152-155]
Corneal Interface Abscess after Excimer Laser in situ Keratomileusis
Authors: Aras Cengiz , Özdamar Aki , Bahçecioglu Halil , Sener Bozkurt 
Published: April 2021

ABSTRACT
Laser in situ keratomileusis (LASIK) carries the risk of infection. We report a case culture-negative interface abscess following LASIK that was successfully treated with antibiotics and povidone iodine. [J Refract Surg 1998;14:156-157]
Laser in situ Keratomileusis for Myopia
Authors: Lavery Frank 
Published: April 2021

ABSTRACT
PURPOSE: To evaluate the efficacy of laser in situ keratomileusis (LASIK) for myopia.
METHODS: We performed LASIK on 55 eyes using the Nidek EC-5000 excimer laser. We altered the PRK algorithms to make them appropriate for LASIK. The Chiron automated corneal shaper was used to create the flap.
RESULTS: A high rate of satisfaction was noted among patients and the complication rate was low. Our retreatment rate was 6%.
CONCLUSION: Our algorithms for myopic LASIK ablations using the Nidek EC-5000 are accurate. [J Refract Surg 1998;14:S177-S178]
Laser in situ Keratomileusis for Hyperopia and Hyperopic Astigmatism
Authors: Ibrahim Osama 
Published: April 2021

ABSTRACT
BACKGROUND: The correction of hyperopia by excimer laser remains challenging because the procedure is followed by regression and loss of effect. We evaluated excimer laser in situ keratomileusis (LASIK) to correct hyperopia and hyperopic astigmatism using the NIDEK scanning slit excimer laser and a modified nomogram.
METHODS: The study included the first consecutive 58 eyes treated for hyperopia and hyperopic astigmatism by one surgeon. All eyes were operated at the Alexandria Eye Center, Alexandria, Egypt using the Nidek excimer laser and the Chiron automated corneal shaper. Astigmatic correction was done Hist by myopic ablation using a 5.0 mm ablation zone and a 5.5 mm transition zone, followed by narrow hyperopic ablation using a 5.5 to 7.5 mm zone.
RESULTS: Mean preoperative cycloplegic spherical equivalent refraction was +3.75 D (range, +1.00 to +6.00 D). Mean preoperative astigmatism was 2.75 D (range, 0 to 4.00 D). After hyperopic LASDX, all eyes had a reduction in their hyperopia, but regression occurred gradually until the last followup examination. At 6 months follow-up, the mean cycloplegic refraction was +2.25 D (range, 0 to +3.25 D). The postoperative astigmatism had a mean of 1.25 D (range, 0 to 2.75 D). Four eyes had a reduction in the quality of vision due to a decentered ablation and a small ablation zone, but no other vision threatening complications were reported.
CONCLUSION: LASIK to correct hyperopia and hyperopic astigmatism is safe, effective, and repeatable. Predictability and long-term stability needs improvement. A better ablation profile and a modified algorithm need to be provided by excimer laser manufacturers. [J Refract Surg 1998;14:S179-S182]
Long-term Results of Photorefractive Keratectomy for Hyperopia and Hyperopic Astigmatism
Authors: Vinciguerra Paolo , Epstein Daniel , Radice Paola , Azzolini Marco 
Published: April 2021

ABSTRACT
PURPOSE: This study was conducted to determine the safety and efficacy of using the Nidek EC5000 excimer laser for photorefractive keratectomy to correct hyperopia and hyperopic astigmatism.
METHODS: We treated 67 eyes of 44 patients for hyperopia and hyperopic astigmatism with the Nidek EC-5000 excimer laser. The algorithm provided an ablation zone of 5.5 mm diameter with the addition of a tapered transition zone of 3.5 mm diameter, for a total ablation of 9 mm diameter.
RESULTS: Uncorrected visual acuity (geometrical mean) changed from 0.16 to 0.37 at 12 months; corrected visual acuity (geometrical mean) changed from 0.8 to 0.89; mean sphere decreased by 2.08 D from 3.76 to 1.40 D (range, 1.70 to 1.68 D) and cylinder by 1.40 D from 2.20 to 1.00 D. Refractive results for =S3.00 D were reasonably accurate and stable, but for >+3.00 D, undercorrection and regression over 1 year were the rule.
CONCLUSION: Hyperopic PRK proved to be a safe technique in regard to the risk of loss of visual acuity with no central corneal opacities and with a generally rapid recovery of baseline spectacle-corrected visual acuity, but the predictability of correction greater than +3.00 needs improvement. [J Refract Surg 1998;14:S183-S185]
A Scanning and Rotating Slit ArF Excimer Laser Delivery System for Refractive Surgery
Authors: Lubatschowski Holger , Kermani Omid , Welling Herbert , Ertmer Wolfgang 
Published: April 2021

ABSTRACT
PURPOSE: This study was designed to investigate the quality of a scanning and rotating slit delivery system of an ArF excimer laser (Nidek EC 5000).
METHODS: The ablation patterns on polymethylmethacrylate (PMMA) wafers weve examined by scanning electron microscopy. The influence of inhomogeneities in the beam profile was simulated on a computer and compared with a conventional large-area ablation system. The impairment of the ablation rate by radiation absorption of the ablation plume was measured as a function of the repetition rate and the application of a fixation ring.
RESULTS: The scanning and rotating slit delivery system is tolerant of small-beam non-homogeneities. The ablation rate is sensitive to the dynamics of the ablation plume.
CONCLUSIONS: Although the operating procedure takes less time with a large-area ablation system, a scanning and rotating delivery system has the advantage of reliable and homogeneous removal of corneal tissue. [J Refract Surg 1998;14:S186-S191]
Efficacy of Topical Nonsteroidal Drops as Pain Relief after Excimer Laser Photorefractive Keratectomy
Authors: Frangouli Andromachi , Shah Sunil , Chatterjee Anupam , Morgan Phil B , Kinsey John 
Published: April 2021

ABSTRACT
PURPOSE: To compare the efficacy of topical aqueous indomethacin and ketorolac for pain relief following excimer laser photorefractive keratectomy (PRK).
METHODS: We conducted a double masked, randomized trial involving 120 patients. All patients received a standard regimen of one of the trial drugs and chloramphenicol ointment to be used four times daily for 2 days. Pain levels and quality were assessed on a 10 cm linear analogue scale prior to each instillation of the topical medication with the McGill pain questionnaire. Pain threshold was evaluated using a modified State Trait Anxiety Inventory questionnaire. Patients were advised to use paracetomol for additional pain relief but were allowed to use any oral analgesic (except nonsteroidal agents) which they documented (type and quantity).
RESULTS: There was no significant difference in pain scores between the groups using indomethacin and ketoralac.
CONCLUSION: We found no significant difference between topical ketoralac and aqueous indomethacin as pain relief following excimer laser PRK. Both drugs seemed to significantly reduce pain. [J Refract Surg 1998;14:S207-S208]
Satisfaction after Photorefractive Keratectomy
Authors: Shah Sunil , Perera Sumith , Chatterjee Anupam 
Published: April 2021

ABSTRACT
PURPOSE: To evaluate patient satisfaction one year after photorefractive keratectomy (PRK) for myopia and myopia astigmatism using the Nidek EC-5000 excimer laser.
METHODS: This study assessed the level of satisfaction of 6280 patients who underwent PRK after a minimum follow-up of 1 year. All patients were asked to enter their level of satisfaction as excellent, good, worthwhile, or disappointed into a networked computer database. Their responses were subsequently analyzed according to baseline and postoperative refractive data.
RESULTS: Patients considered their results to be as follows: 82.3% good or excellent, 14.9% worthwhile, and 2.8% were disappointed with the outcome.
CONCLUSION: A high percentage of patients were satisfied with the outcome following PRK. However, a fair number (14%) of patients considered the treatment to be worthwhile but it did not meet their expectations. Extensive counseling and inculcating realistic expectations before treatment is essential in achieving better patient satisfaction. [J Refract Surg 1998;14:S226-S227]
Iatrogenic Keratectasia after Laser in situ Keratomileusis
Authors: Seiler Theo , Koufala Konstantina , Richter Gernot 
Published: April 2021

ABSTRACT
BACKGROUND: Lamellar refractive surgery reduces the biomechanical strength of the cornea which may lead to mechanical instability and keratectasia.
METHODS: Three eyes had laser in situ keratomileusis (LASIK) for myopia from -10.00 to -13.50 D. The procedures were performed with two different wide-field excimer lasers and two different microkeratomes. The patients were followed up to 1 year after surgery.
RESULTS: Central steep areas developed between 1 and 8 months after surgery. In contrast to conventional central steep islands, these showed rapid progression and were interpreted as keratectasia.
CONCLUSION: Iatrogenic keratectasia represents a complication after LASDX that may limit the range of myopia correction. Based on biomechanical considerations we recommend a residual corneal thickness of the stromal bed of at least 250 µm. [J Refract Surg 1998;14:312-317]
Five and Three Year Follow-up of Photorefractive Keratectomy for Myopia of -1 to - 6 Diopters
Authors: Matta Camille S , Piebenga Larry W , Deitz Michael R , Tauber Joseph , Garner Lynne P 
Published: April 2021

ABSTRACT
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 nun. Our initial series of 133 eyes were treated in four groups: DA, DB, ID and ID 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 DA and DB were followed for 5 years and Groups ID and ID No Nitrogen for 3 years. Group DA 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 DB, 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 ID 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 ID 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 DA and DI continued to be stable; Groups HR and HI No Nitrogen showed mild regression that was not statistically significant. [J Refract Surg 1998;14:318-324]
Unilateral Refractive Keratotomy for Anisometropia
Authors: Maden Ahmet , Erkin Esin F , Oner Ferit H 
Published: April 2021

ABSTRACT
BACKGROUND: In anisometropia, the asymmetry of refractive error produces disparity of image magnification (aniseikonia) that can create visual discomfort, especially when asymmetry is 3.00 diopters or more.
METHODS: A prospective study of 20 eyes of 20 patients between 18 and 61 years of age who underwent unilateral radial and/or transverse keratotomy was conducted; results of at least 12 months follow-up are presented. The efficacy of keratotomy was evaluated by the following criteria: 1) change in spherical and cylindrical refraction, 2) decrease in refraction difference between two eyes of each patient, 3) change in spectacle-corrected visual acuity, and 4) change in binocular vision functions and asthenopic complaints.
RESULTS: Mean decrease in spherical refractive error was 3.66 ±1.58 D (range, 1.25 to 7.50 D) and 2.08 ± 0.81 D (range, 1.00 to 3.50 D) in astigmatic refraction. The mean refraction difference between two eyes was 4.90 ± 2.20 D preoperatively, and this difference regressed to 1.79 ± 1.42 D postoperatively. Spectacle-corrected visual acuity increased in seven eyes (35%), remained the same in 12 eyes (60%) and decreased in one eye (5%). All patients reported relief of asthenopic complaints. Fusion amplitudes increased in 12 (60%) patients. Stereoscopic vision improved in five (25%) patients.
CONCLUSION: Monocular refractive keratotomy can significantly decrease anisometropia. [J Refract Surg 1998;14:325-330]
Measurement of Radial Keratotomy Clear Zone Diameters
Authors: Grimmett Michael R , Ogawa Gregory S H 
Published: April 2021

ABSTRACT
BACKGROUND: To compare the accuracy of photographic measurements to slit-lamp measurements of radial keratotomy clear zone diameters in order to develop an independent, objective, unbiased, and reproducible method of verifying clinical observations.
METHODS: Twenty-five patients (48 eyes) following radial keratotomy had matched slit-lamp and photographic measurements of the diameter of the central clear cornea between the ends of opposite radial incision pairs. Matched slit-beam, photographic, and pathologic observations were compared statistically.
RESULTS: Two hundred fifty-four slit-lamp clear zone diameter measurements were obtained. In twenty instances (8%), the radial incision end-point could not be identified on the photograph. For the remaining 234 measurements, the mean slit-lamp clear zone diameter was statistically smaller than the photographic measurement by 0.03 mm (/-test, ? = 2.2 x 10"5). The slit-lamp and photographic clear zone measurements were strongly positively correlated (Pearson r = 0.99, ? < 1.0 ? IO15). Matched slitlamp, photographic, and pathologic clear zone measurements (N=8) in one excised corneal button were not statistically different.
CONCLUSIONS: For radial keratotomy clear zone diameters, slit-beam measurements and photographic caliper measurements yield indistinguishable results that are highly concordant over a wide range of diameters. Both slit-beam and photographic measurements yield accurate and reliable results that reflect the true pathologic achieved clear zone diameter following radial keratotomy surgery. [J Refract Surg 1998;14:331-337]
Principles and Microscopic Confirmation of Surface Quality of Two New Waterjet-based Microkeratomes
Authors: Gordon Eugene , Parolini Barbara , Abelson Marc 
Published: April 2021

ABSTRACT
PURPOSE: The HydroBlade and the HydroBrush keratomes are waterjet-based devices for corneal surgery that operate at normal intraocular pressure in two different modes: removal of parallel or shaped lenticules or hinged flaps with a small diameter, high speed waterjet; and removal of the epithelium with a waterjet sheet. The operating principles as well as histology of the cut surfaces are described.
METHODS: A flap was made in one cadaver eye with a Chiron ACS keratome and in the second eye with the HydroBlade keratome. The epithelium was removed in one cadaver eye with a surgical blade and in the second eye by the HydroBrush keratome. Scanning and transmission electron microscopy and light microscopy was obtained.
RESULTS: The HydroBlade keratome cleaved only cross-linking fibrils and left intact keratocytes. Shape and dimensions of the flap were accurate. There was no observable hydration or significant heating of the tissue. Mechanical forces on the cornea were small. The HydroBrush keratome removed the epithelium quickly, left no epithelial debris, and did not damage Bowman's layer.
CONCLUSION: With the HydroBlade keratome, the cuts are ideal blunt dissections. Epithelial removal with the HydroBrush keratome is effective and quick. [J Refract Surg 1998;14:338-345]