bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isomorphic Corneal Topography: A Clinical Approach to 3-D Representation of the Corneal Surface
Authors: Young Joshua A , Siegel Irwin M 
Published: April 2021

ABSTRACT
BACKGROUND: Newer methods of refractive surgery produce their effect by reshaping the corneal surface. It follows that topographic representations, used primarily to map refractive power, should now emphasize morphology and contour features.
METHODS: We introduce a procedure using commercially available instrumentation which provides isomorphic three-dimensional cornea) topography. The representations may be displayed either as refractive power, as is conventionally done, or as the more surgically relevant contour configuration. These images contain data points that are continuous rather than stepped as in the familiar color-coded displays.
RESULTS: The technique proved easy to execute requiring no special software or mainframe computing. The corneal displays generated were freely rotatable and rescalable.
CONCLUSIONS: In addition to producing clear and intuitive three-dimensional representations, the digital graphics environment allows manipulation unavailable in the conventional color-coded format; such representations should be particularly valuable for pre- and postoperative evaluation. Refract Corneal Surg 1993;9:74-78.)
Aspheric Photorefractive Keratectomy With Excimer Laser
Authors: Seiler Theo , Genth Uwe , Holschbach Andreas , Derse Matthias 
Published: April 2021

ABSTRACT
BACKGROUND: Increased spherical aberration of the cornea is a common finding after excimer laser keratorefractive keratectomy. The shape of the paracentral cornea is probably related to the incidence of side effects like glare and halos at night depending on ablation zone size and pupil diameter. Aspheric curvature changes of the paracentral cornea at the edge of the ablation may decrease those side effects.
MATERIALS AND METHODS: Fifteen patients were treated with photorefractive keratectomy for myopia correction with a Summit excimer laser (Summit Technology, Waltham, Mass), one eye using a standard spherical algorithm and the fellow eye using a new aspherical algorithm. Eyes were followed for 6 to 18 months.
RESULTS: None of 15 patients reported halos in the aspherically corrected eye stronger than in the fellow eye, whereas five patients claimed stronger halos in the spherically corrected eye. The effective clear zone size was 3. 16 ± 0.35 mm in the spherical cases compared to 3.43 ± 0.31 in the aspherical cases, although the same ablation zone diameters of 5 mm were used. This difference is highly statistically significant. Effective spherical aberration based on raytracing analysis of the central 5 mm of the corneal topographic maps was significantly smaller in the corneas with aspheric correction than in those with spheric corrections.
CONCLUSION: These results indicate better optical homogeneity in eyes after aspheric photorefractive keratectomy for myopia compared to standard spherical corrections. (Refract Corneal Surg. 1993;9:166-172.)
RÉSUMÉ
INTRODUCTION: Une augmentation dans l'écart sphérique de la cornée suit souvent la kératectomie photorefractive au laser excimer. La forme de la cornée paracentrale a probablement un rapport avec les effets secondaires comme Péblouissement et les halos nocturnes, selon la taille de la zone d'ablation et la diamètre de la pupille. Il est possible que des changements asphériques dans la courbure cornéenne puissent réduire ces effets secondaires.
METHODS: Quinze patients ont subi la kératectomie photorefractive démyopisante avec le laser excimer de Summit (Waltham, Mass), une oeil selon un algorithme sphérique ordinaire et l'autre selon l'algorithme asphérique nouveau. Le suivi variait de 6 à 18 mois.
RÉSULTATS: Aucun des 15 patients n'a indiqué de halos plus forts dans l'oeil opéré asphériquement que dans l'autre oeil, tandis que cinq patients ont rapporté des halos plus forts dans l'oeil sphériquement corrigé. La taille e la zone claire effective était de 3, 16 ±0,35 mm dans les cas sphériques par comparaison avec 3,43±o,31 dans les cas asphériques, bien qu'on ait utilisé le même diamètre de la zone d'ablation, 5 mm. Cette différence est statistiquement très significative. L'écart sphérique réel, basé sur l'analyse de la recherche des rayons pour les 5 mm qui forment le centre de la cornée était beaucoup plus petit chez les patients à la cornée à correction asphérique que chez ceux dont la correction est sphérique.
Computer Program to Calculate Vectorial Change of Refraction Induced by Refractive Surgery
Authors: Calossi Antonio , Verzella Franco , Penso Andrea 
Published: April 2021

ABSTRACT
BACKGROUND: After refractive surgery, there may be changes in the spherical and the cylindrical components of the ametropia. In astigmatism, there may be variations in both the power and the axis. The best way to describe change in astigmatism caused by surgery is by vectorial analysis, which Indicates the changes in power and the axis. However, In clinical practice, this procedure is limited by the tedious calculations required to establish the oblique cylinder combinations.
METHODS: We propose a computer program for the calculation, by vectorial analysis, of the refractive changes induced by surgery. The program allows for reference to refractive data or keratometric readings. When the refractive data are considered, it is also possible to obtain the transposition of the correction values from the spectacle plane to that of the cornea. Finally, the program enables the user to calculate the coupling ratio.
RESULTS: Some selected surgical cases are discussed by way of example.
CONCLUSIONS: We think that this program will be a simple and accurate means of evaluating the results of refractive and corneal surgery. (Refract Corneal Surg 1993;9:276-282.)
RESUMÉ
INTRODUCTION: Suivant la chirurgie refractive il peut exister des changements dans les éléments sphériques et cylindriques de l'amétropie. L'analyse vectorielle, qui indique les changements dans la pouvoir et l'axe de l'astigmatisme, est la meilleure façon de décrire ces effets. Néanmoins, les calculs ennuyeux qu'il faut pour établir les combinaisons de cylindres obliques sont peu pratiques en clinique.
METHODES: Nous proposons un programme informatique pour calculer par l'analyse vectorielle les changements réfractifs induits par la chirurgie. Le programme permet d'obtenir des références aux données réfractives et kératométriques. En utilisant les données réfractives on peut transposer la correction optique du plan des lunettes jusqu'à la corneé. Finalement, le programme permet calcul du rapport de couplage.
RÉSULTATS: Nous discutons de quelques malades choisis.
CONCLUSIONS: Nous espérons que ce programme informatique soit un moyen simple et précis afin d'évaluer les résultats des chirurgies cornéennos et réfractives. (Translated by Rob Mack, MD, Iowa City, la.)
SOMMARIO
PREMESSA: Dopo un intervento di chirurgia refratfrva si possono avere variazioni della componente sferica e di quella cilìndrica dell'ametropia. Per quanto riguarda l'astigmatismo, le variazioni si possono avere sia nel potere che nell'asse. Il modo più corretto per descrivere la variazione dell'astigmatismo indotta dalla chirurgia è l'analisi vettoriale, che Indica la variazione sia del potere che deìVasse. D'altra parte nella pratica clinica questa procedura è limitata dalla complessità dei calcoli necessari a risolvere (a combinazione di cilindri obliqui.
Assessing the Efficacy of Topical Corticosteroids Following Radial Keratotomy
Authors: Haverbeke Luc 
Published: April 2021

ABSTRACT
BACKGROUND: The postoperative use of topical corticosteroids may decrease the risk for regression and thereby improve the refractive outcome following radial keratotomy.
METHODS: Twenty patients with identical preoperative refractions in each eye underwent bilateral radial keratotomy in one sitting. One eye was treated with dexamethasone twice daily for 3 months postoperatively; the fellow eye was not.
RESULTS: Three months postoperatively, there was no difference between the refractions of the two groups of eyes.
CONCLUSION: The use of topical dexamethasone after radial keratotomy for 3 months does not improve the refractive outcome, [Refract Corneal Surg 1993;9:379-382.)
Radial Keratotomy Does Not Affect Intraocular Pressure
Authors: Sastry Srinivas M , Sperduto Robert D , Waring George O , Remaley Nancy A , Lynn Michael J , Blanco E , Miller David N 
Published: April 2021

ABSTRACT
BACKGROUND: Recent reports have suggested that a secondary effect of radial keratotomy may be a reduction in intraocular pressure (IOP) levels.
METHODS: In an effort to study the relationship of radial keratotomy to IOP, we compared the mean IOP from the baseline and follow-up visits during 1 year after surgery of operated versus nonoperated eyes of patients enrolled in the Prospective Evaluation of Radial Keratotomy (PERK) study. To investigate if radial keratotomy had more of an effect on eyes with higher baseline IOPs, the same analysis was performed on a subset (134 patients) who had a baseline IOP of 15 mm Hg or greater.
RESULTS: The average baseline IOP for both operated eyes and nonoperated eyes was 14.6 mm Hg. There was no significant difference in mean IOP between operated and nonoperated eyes across all time points (p=.18). Although mean IOP changed over time, it did not clinically differ in operated versus nonoperated eyes at any time point. These findings were similar in the analysis of eyes with higher baseline IOP (15 mm Hg or greater).
CONCLUSION: We conclude that the radial keratotomy performed in the PERK study had no effect on IOP within 1 year after surgery. (Refract Corneal Surg. 1993;9:459-464.)
RÉSUMÉ
INTRODUCTION: Plusieurs rapports ont suggéré que la kératotomie radiaire peut réduire la pression jntraoculalre comme effet secondaire.
MÉTHODES: Afin d'étudier les effets de la kératotomie radiaire vis à vis de la pression întraoculaire nous avons comparé la pression moyenne întraoculaire lors de la première visite avec les pressions mesurées pendant une année en suite post-opératoire sur les yeux opérés et les yeux non-opérés chez les patients dans L'Etude Prospective de la Kératotomie Radiare (PERK, en Anglais). Pour déterminer l'effet de la kératotomie radiaire sur les yeux avec une pression plus haute avant traitement, ia même analyse fut utilisée chez 134 patients avec une pression d'au moins 15 mm Hg.
RÉSULTAT: La pression moyenne întraoculaire chez les yeux opérés et les yeux non-opérés était de 14,6 mm Hg. Il n'existait à aucun moment une différence significative dans la pression moyenne întraoculaire entre les yeux opérés et les yeux non-opérés (p=0,18). Quoique la pression moyenne întraoculaire variait avec le temps, elle n'a jamais changé entre les yeux opérés et les yeux non-opérés. Les résultats furent similaires avec les yeux ayant une pression plus élevée au début r>15mmHg).
CONCLUSION: Nous concluons que la kératotomie radiaire dans l'étude PERK n'a eu aucun effet sur la pression întraoculaire post-opératoire. (Translated by Robert Mack, MD, Iowa City, la.)
Lamellar Keratoplasty for Hyperopia
Authors: Manche Edward E , Judge Anisha , Maloney Robert K 
Published: April 2021

ABSTRACT
PURPOSE: Lamellar keratoplasty for hyperopia (automated lamellar keratoplasty for hyperopia) can correct hyperopia by weakening the cornea with a deep lamellar resection. The safety and efficacy of the procedure is uncertain.
METHODS: Twenty-four eyes of 17 patients underwent hyperopic lamellar keratoplasty using the automated corneal shaper (Chiron Corp, Irvine, Calif) by one surgeon using a flap technique. The mean attempted correction was +3.90 ± 0.90 D (range, +2.00 to +6.00). The eyes were followed for 1 month (23 eyes) to 6 months (17 eyes).
RESULTS: Six months after hyperopic lamellar keratoplasty, the mean difference between attempted and achieved correction was an undercorrection of +1.40 ± 0.80 diopters (D) with 7 of 17 eyes within 1.00 D of the attempted correction. No eyes were overcorrected, and 15 eyes were undercorrected. In eyes with a refractive goal of emmetropia, uncorrected visual acuity was 20/40 or better in 13 of 15 eyes and 20/20 or better in 8 of 15 eyes. No eye lost two or more lines of spectacle-corrected visual acuity at 3 or 6 months postoperatively. Between 1 and 6 months, there was a mean hyperopic shift of 0.20 D. There was clinically significant epithelial ingrowth into the interface in two eyes.
CONCLUSION: Hyperopic lamellar keratoplasty is an effective method of reducing hyperopia and induces little irregular astigmatism. The nomogram we used produces a consistent undercorrection. Refraction appears to stabilize at 1 month, but longer follow up is necessary to assess stability. [J Refract Surg. 1996;12:42-49.]
Keratocyte-Populated Collagen Gel as an In Vitro Model of Excimer Laser Keratectomy
Authors: Wee Won Ryang , Nassaralla Belquiz A , Garbus Jenny , McDonnell Peter J 
Published: April 2021

ABSTRACT
BACKGROUND: To develop an in vitro model to study the effects of excimer laser keratectomy on corneal stromal cells, we evaluated two types of collagen gel populated with keratocytes.
METHODS: Keratocyte-populated collagen gels were prepared with type I collagen in 6-well plates or in culture plate inserts, the bottom of which consisted of a nitrocellulose membrane, contained within 6-well plates. The gels were ablated by the 193-nm excimer laser, set to ablate 50, 100, or 200 µm deep, and was observed under a phase-contrast microscope for 2 days.
RESULTS: Keratocytes cultured in collagen gel developed cytoplasmic processes and formed networks of interconnected cells. Cells within the ablated area in the 6-well plates began to lose their cytoplasmic processes and became round approximately 3 hours after excimer laser ablation. These cellular changes were more prominent in the gels ablated to a depth of 200 µm. Cells outside of the ablation zones ill the 6-well plates and the culture plate inserts remained intact.
CONCLUSIONS: These results suggest the use of keratocyte-populated collagen gel as an in vitro model of cellular response to excimer laser keratectomy and also suggest that gel prepared in culture plate inserts is the preferred method. [J Refract Surg. 1996;12:98-102.]
Phototherapeutic Keratectomy for Climatic Droplet Keratopathy
Authors: Badr Ihsan A , Al-Rajhi Ali , Wagoner Michael D , Dunham Timithy , Teichmann Klaus D , Cameron James A 
Published: April 2021

ABSTRACT
BACKGROUND: Phototherapeutic keratectomy (PTK) is an effective treatment for many superficial corneal disorders. The efficacy of PTK for the treatment of climatic droplet keratopathy (CDK) has not been reported.
METHODS: We report the results of excimer laser (Summit Technology, Inc, Waltham, Mass) PTK on 75 eyes (67 patients) with "smooth" climatic droplet keratopathy (55 eyes) and "irregular" climatic droplet keratopathy (20 eyes) in whom more than 6 months of follow up are available.
RESULTS: PTK was successful in reducing corneal opacification in both smooth (98%) climatic droplet keratopathy and irregular (80%) climatic droplet keratopathy. Achievement of a clear or mildly hazy cornea following PTK was more likely to occur with smooth (80%) climatic droplet keratopathy than irregular (25%) climatic droplet keratopathy (P=0.01). Eyes with smooth climatic droplet keratopathy were more likely to obtain more than one line of improved uncorrected (56% vs. 25%) or spectacle-corrected visual acuity (61.8% vs. 21.2%) than those with irregular climatic droplet keratopathy (P=0.03 and 0.005, respectively). Delayed re-epithelialization (longer than 14 days) was more common in irregular CDK (21%) than in smooth CDK (9%), as was the incidence of secondary microbial keratitis (10.0% vs. 1.8%).
CONCLUSIONS: PTK is effective in reducing superficial corneal opacification in CDK, although serious complications may occur, especially in advanced irregular CDK. [J Refract Surg. 1996;12:114-122.]
Eye Infections After Refractive Keratotomy
Authors: Jain Sandeep , Azar Dimitri T 
Published: April 2021

ABSTRACT
BACKGROUND: Ocular infections are serious and potentially vision-threatening complications of refractive keratotomy. We have performed an integrative review of published literature to address important issues concerning these complications.
METHODS: Articles in MEDLINE and published manuscripts and abstracts reporting previously unpublished cases of infections after refractive keratotomy were systematically identified and reviewed. Our review did not target patients treated with relaxing incisions for postkeratoplasty astigmatism. Pertinent data were abstracted and analyzed.
RESULTS: Forty-three cases (47 episodes: 42 keratitis and 5 endophthalmitis) of infection appeared in 26 published reports from 1975 to 1994. The frequency ranged from 0.25% to 0.70%. In 22 (47%) eyes, infection occurred before 2 weeks. Thirty-five (74%) infections were located in the inferior half of the cornea, and 22 (62%) were located in the inferotemporal quadrant. Thirty-one (66%) infections were bacterial (32% gram-positive, 23% gram-negative, 9% acid fast, 496 unknown), 5% fungal, 6% viral, 19% sterile, and 4% of unknown origin. Spectacle-corrected visual acuity after conservative treatment was 20/40 or better in 70% of eyes. Penetrating keratoplasty was performed in six cases. Potential associations included reoperations in 12 (26%) eyes, postoperative contact lens wear in 7 (15%), and intraoperative perforation in 7 (15%).
CONCLUSIONS: The published literature indicates that infections after refractive keratotomy may compromise visual function. Approximately half of the infections occur in the first 2 weeks. Reoperations, postoperative contact lens wear, and intraoperative perforations may be significant risk factors. [J Refract Surg. 1996;12:148-155.]
Videokeratography of Keratoconus in Monozygotic Twins
Authors: Parker James , Ko William W , Pavlopoulos George , Wolfe Peter J , Rabinowitz Yaron S , Feldman Sandy T 
Published: April 2021

ABSTRACT
PURPOSE: To determine the corneal topographic appearance in a pair of monozygotic twins and family members of the twins because one of the twins had keratoconus and the other appeared normal by clinical examination.
METHODS: Clinical examination and videokeratography (Topographic Modeling System, Tomey) of the patient, his monozygotic twin brother, an older brother, and his parents were performed. The I-S values (difference in the average dioptric powers of symmetrical points between the inferior and superior cornea) were calculated.
RESULTS: The patient, a 28-year-old man, had clinical keratoconus confirmed with videokeratography. Clinical examination of family members including a twin brother, an older brother and both parents revealed no corneal abnormalities. Videokeratography of the clinically normal twin brother showed inferior steepening with progression over time. The I-S value of the clinically normal brother was 1.36 (right eye) (greater than 2.00 SD of normal controls), which progressed to 1.69 (right eye), 1.32 (left eye) 5 months later and to 1.87 (right eye), 1.43 diopters (D) (left eye) 14 months later. Minimal asymmetric inferior steepening was noted in an older brother who had an I-S value of 0.81 (right eye), 1.27(left eye). The mother appeared topographically normal.
CONCLUSIONS: This study lends support to the existence of subclinical keratoconus detectable by videokeratography only. [J Refract Surg. 1996;12:180-183.]
Early Results of Photorefractive Keratectomy for Myopic Astigmatism
Authors: Kaskaloglu Mahmut 
Published: April 2021

ABSTRACT
BACKGROUND: The Technolas Keracor 116 excimer laser has been used to correct myopic astigmatism. The purpose of this study was to evaluate the early results in our patients.
METHODS: The Technolas Keracor 116 excimer utilizes a scanning beam to correct myopic astigmatism. Following the correction of the astigmatic error, spherical myopic component is then treated. Twenty-eight eyes with myopic astigmatism were treated utilizing a 4 x 12 mm ablation zone for astigmatism and 4.5 nun to 6.6 mm transition zone for the spherical component at the same session. The mean preoperative spherical equivalent refraction was -4.87 ± 3.48 diopters (D) (range: -1.00 to -14.25) and the mean preoperative astigmatic error was -2.53 ± 1.49 D (range: -1.00 to -6.00 D) All eyes received dexamethasone eye drops for 3 months.
RESULTS: At 6 months, the mean spherical equivalent refraction was +0.23 D (range +1.38 to -1.50 D), the mean postoperative refractive cylinder was -0.16 ± 0.99 D (range: +1.50 to -2.00 D) and 78% of the eyes had a refraction within ± 1 D. Fifty-five percent achieved 20/40 or better uncorrected visual acuity. In three cases there was one line loss and in two cases there was two line loss in best corrected spectacle visual acuity.
CONCLUSIONS: Early results from this study suggest that excimer laser photorefractive keratectomy effectively reduces myopic astigmatism. The treatment of astigmatism offers a new challenge for excimer laser corneal surgery. Lasers utilize different methods to control the beam that reshapes the cornea.1-5 [J Refract Surg. 1996;12:S258-S260.]
Photorefractive Keratectomy With a Transition Zone for Myopia from -7 to -14 Diopters
Authors: Siganos Dimitrios S , Pallikaris loannis G , Margaritis Vasilios N 
Published: April 2021

ABSTRACT
PURPOSE: To study transition zone excimer laser photorefractive keratectomy (PRK) in moderate and high myopia defined as a spherical equivalent of -7.00 diopters (D) or more. The follow-up period was 18 months.
METHODS: Forty eyes of 40 patients with myopia of 7.00 to - 13.50 D (mean ± SD, -921 ± 1.98) underwent transition zone (5.0 to 7.0 mm transition zone) PRK using the Aesculap Meditec Mel 60 excimer laser. The mean attempted correction was 8.3 ± 1.64 D (range: -6.50 to -12.00 D).
RESULTS: At 18 months, 83% achieved an unaided visual acuity of 20/50 or better and HOW 12% 20/25 or better. Eighty-eight percent were within ±2 D of emmetropia. The mean spherical equivalent was -1.1 D (+3.00 to -9.00 D).
CONCLUSIONS: Transition zone PRK is useful in moderate to high myopia. Regression, as well as overcorrection are issues for further investigation. [J Refract Surg. 1996;12:S261-S263.]
Disability Glare After Excimer Laser Photorefractive Keratectomy for Myopia
Authors: Niesen Ulrike M , Businger Urs , Schipper Isaak 
Published: April 2021

ABSTRACT
BACKGROUND: A change of corneal topography and haze after excimer laser photorefractive keratectomy (PRK) can reduce contrast sensitivity and cause glare. Both glare and contrast sensitivity can be examined in a reproducible manner with one instrument.
METHODS: We have used the Berkeley Glare Test to examine 46 eyes of 32 patients before and 1, 3, 6, 9, and 12 months after excimer laser PRK for moderate to high myopia. Multiple regression analysis was used for statistical analysis.
RESULTS: High contrast visual acuity showed a statistically significant deterioration during the first 6 months after PRK (p=0.01); 1 year after treatment visual acuity returned to almost pretreatment levels (p=0.2). High- and low contrast visual acuity under glare deteriorated significantly 3 months after PRK and had only risen slightly 1 year later (p≤0.0065). A similar development could be observed for the low contrast visual acuity without glare.
CONCLUSION: Although high contrast visual acuity recovers by 1 year after PRK, low contrast visual acuity and glare deteriorate significantly and do not recover, even after 1 year. [J Refract Surg. 1996;12:S267-S268.]