bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bacterial Keratitis Following Phototherapeutic Keratectomy
Authors: Al-Rajhi Ali A , Wagoner Michael D , Badr Ihsan A , Al-Saif Abdulrazzaq , Mahmood Muneera 
Published: April 2021

ABSTRACT
BACKGROUND: Phototherapeutic keratectomy (PTK) is effective in the treatment of many superficial corneal disorders. The incidence of bacterial keratitis following PTK has not been assessed in a large, prospective clinical trial.
METHODS: We report three cases of bacterial keratitis that occurred in a prospective study of 258 consecutive PTK procedures at King Khaled Eye Specialist Hospital.
RESULTS: Three (1.2%) of 258 eyes developed bacterial keratitis during a period of follow up ranging from 1 to 24 months. All three cases were in 183 eyes (1.6%) with a diagnosis of climatic droplet keratopathy, while no cases were observed in 75 eyes with other anterior corneal disorders. Gram-positive species (Streptococcus pneumonia in two, coagulase-negative Staphylococcus in one) were the predominant species isolated from all three cases. Two of the cases were polybacterial. The final visual outcomes ranged from 20/125 to 20/400.
CONCLUSIONS: The risk of bacterial keratitis following treatment of superficial corneal disorders with PTK is low but its occurrence may adversely affect the final visual outcome. [J Refract Surg. 1996;12:123-127.]
Communicating With Keratography
Authors: Grimm Bradford B 
Published: April 2021

ABSTRACT
BACKGROUND: Videokeratographic images are important in understanding the corneal topographic changes made by refractive surgery. These images are often poorly presented and cluttered with unnecessary, distracting information.
METHODS: A simple method for producing better quality keratographic images, using the Computed Anatomy TMS-1 instrument and an IBM-compatible computer running Microsoft PowerPoint, is described. Scaling of the color-coded dioptric steps after refractive surgery is discussed.
RESULTS: This method yields a high-quality image, suitable for presentation or publication, and displays the corneal topography clearly and concisely.
CONCLUSION: High-quality videokeratographic images can be easily produced by computer. Modification of the image with better scaling and masking of unnecessary information enhances understanding of corneal topography. [J Refract Surg. 1996;12:156-159.]
Hyperopic Shift and Myopic Regression in a Patient 7 Years After Bilateral Refractive Keratotomy
Authors: Chavez Salvador , Celikkol Leyla , Feldman Sandy T 
Published: April 2021

ABSTRACT
PURPOSE/METHODS: To report a patient who developed hyperopic progression in one eye and myopic regression in the other eye following bilateral, non-simultaneous refractive keratotomy.
RESULTS: Uncorrected visual acuity improved to 20/25 and 20/25-2 in the right and left eyes, respectively, 3 months following refractive keratotomy (one procedure in the right eye, two procedures in the left eye). The visual acuity was not stable over time and almost 8 years after surgery, uncorrected distance visual acuity was 20/40- and 20/200. The spherical equivalent refraction of the right eye progressed from -0.50 diopter (D) 3 months after surgery to +1.25 D several years later. The left eye regressed from a spherical equivalent refraction of -0.75 D 3 months after the second surgery to -2.50 D more than 7 years postoperatively. Slit-lamp microscopy disclosed deeper, opaque incisions in the hyperopic eye, and shallower and more transparent incisions in the myopic eye.
CONCLUSIONS: The shift toward hyperopia and myopia in an individual suggest that instability of the radial keratotomy wound may be related to local wound healing events that are, in part, related to incision depth. [J Refract Surg. 1996;12:160-162.]
Photorefractive Keratectomy Following Radial Keratotomy
Authors: Burnstein Yochanan , Hersh Peter S 
Published: April 2021

ABSTRACT
BACKGROUND: Excimer laser photorefractive keratectomy (PRK) has been used to correct residual myopia in eyes that have had refractive keratotomy.
METHODS: Nine eyes of eight patients were studied at a mean of 13 months after PRK. Previous procedures included radial keratotomy (9 eyes) and myopic keratomileusis (1 eye). PRK was performed using a Summit Technology excimer laser with a 5.0-mm diameter ablation zone.
RESULTS: Uncorrected visual acuity improved in 7 of 9 eyes. The refractive outcome was within 1.00 diopter (D) of attempted correction for 3 of 9 eyes. Spectacle-corrected visual acuity decreased 2 or more Snellen lines in 2 of 9 eyes. Subepithelial corneal stromal haze was seen 1 month postoperatively in 6 of 8 eyes and was present in 4 of 6 eyes at 1 year. Stromal haze was associated with regression of the refractive effect of the PRK.
CONCLUSIONS: PRK in eyes with previous radial keratotomy appears to be less predictable and may be associated with greater corneal haze and regression of refractive correction than in previously unoperated eyes. Activation of stromal fibroblasts in the previous corneal incisions may cause these findings. [J Refract Surg. 1996;12:163-170.]
Cutting the Cornea With a Waterjet Keratome
Authors: Lipshitz Isaac , Bass Rephael , Loewenstein Anat 
Published: April 2021

ABSTRACT
BACKGROUND: Waterjet cutting is an advanced technology. It consists of a cutting tool that uses a very thin stream of ultra-high-pressure water forced at high velocity through a very small nozzle, creating a very sharp knife. We report on the first experimental use of waterjet technology to reshape the cornea.
METHODS: The system was used in vitro on 10 bovine eyes, and in vivo on 10 albino rabbit eyes. Using the waterjet keratome (Lipshitz-Bass knife, LBK) lamellar corneal incisions were performed. Histological examinations were performed.
RESULTS: A waterjet stream was found to be capable of incising corneas at relatively low energy levels (4000 PSI). Good surface quality could be obtained, and there was no collateral damage to the remaining portion of the cornea, lens, or retina. In the in vivo experiments, the epithelium healed within 48 hours.
CONCLUSIONS: These preliminary experiments suggest that waterjet technology can be an effective instrument for reshaping the cornea. [J Refract Surg. 1996;12:184-186.]
Mathematical Simulation of Retinal Image Contrast After Photorefractive Keratectomy With a Diaphragm Mask
Authors: Ludwig Klaus , Schäffer Peter , Gross Herbert , Lasser Theo , Kampik Anselm 
Published: April 2021

ABSTRACT
BACKGROUND; Photorefractive keratectomy (PRK) using a dilating diaphragm mask engraves a delicate three-dimensional staircase pattern into a formerly smooth corneal surface. The created steps are later smoothed by tear film and wound healing processes. The present study investigates, in a mathematical simulation, the effects that such staircase patterns and their smoothing may have on retinal image contrast.
METHODS: All simulations are based on the Gullstrand eye model and calculate retinal image contrast from point spread function (PSF) analysis of Gullstrand eyes treated by simulated PRK under various conditions.
RESULTS: The simulations indicate that PRK can reduce retinal contrast markedly. The most critical factor for such a reduction is the step height of the ablation pattern. With step heights below 0.4 µm, loss of contrast due to the created staircase pattern is always moderate and should be restored during early wound healing. Complete wound healing may smooth out larger step heights. Micromovements during PRK also can lead to partial loss of retinal image contrast.
CONCLUSIONS: Simulation of retinal contrast after PRK shows that step heights below 0.4 µm seem to be acceptable. A minimization of the micromovements during PRK can offset some of the reduction of retinal contrast. [J Refract Surg. 1996;12:248-253.]
Comparison of Corneal Epithelial Wound Healing After Photorefractive and Lamellar Keratectomy
Authors: Reidy James J , Jacobson Mark S , Thompson Hilary W , Beuerman Roger W , Leach David H , McDonald Marguerite B 
Published: April 2021

ABSTRACT
BACKGROUND: The rate of corneal epithelial wound healing may be determined, in part, by the characteristics of the stromal surface. The excimer laser has the ability to produce a highly uniform ablated surface, which may facilitate reepithelialization after photorefractive keratectomy (PRK).
METHODS: The rate of corneal epithelial wound healing after excimer laser PRK was compared with the rate of reepithelialization after manual lamellar keratectomy. Ten rabbits received a 4-mm diameter ablation in one eye (fluence = 160 m J/cm2) and a shallow, 5-mm diameter, manual lamellar keratectomy in the contralateral eye. At 0, 4, 8, 12, 24, 36, 48, 60, and 72 hours after wounding, sodium fluorescein was instilled, and photographs were taken, converted to video images, and digitized. Wound area was calculated for each time point and converted to wound radius; the slopes of the wound radius, plotted over time, were compared to determine rates of healing. Scanning electron microscopy was performed immediately after wounding to examine surface regularity.
RESULTS: By 24 hours after wounding, corneas that had undergone PRK demonstrated a significantly faster rate of epithelial wound healing compared with eyes that underwent lamellar keratectomy (33.4±1.9 um/hr vs 27.8±1.4 um/hr, respectively, for 12 to 72 hours) (p<0.0001). Scanning electron microscopy showed greater stromal surface irregularity in the corneas that had undergone lamellar keratectomy, compared with the laser-ablated corneas.
CONCLUSIONS: This study demonstrates that the rate of epithelial wound healing is significantly faster after excimer laser PRK than after lamellar keratectomy in the rabbit. Variations in surface regularity and wound edge profile may contribute to differences in wound healing. [J Refract Surg. 1996;12:352-357.]
Control of Pain After Photorefractive Keratectomy
Authors: Verma Seema , Marshall John 
Published: April 2021

ABSTRACT
BACKGROUND: The inadequate control of pain after photorefractive keratectomy remains an important issue for both patients and clinicians.
METHOD: A survey of postoperative pain regimens used in excimer centers worldwide was carried out. A pilot study to assess the temporal basis of pain after photorefractive keratectomy was done by using a visual analog pain score in 30 patients. A comprehensive literature search was undertaken to ascertain the suitability of topical ophthalmic anesthetics in controlling pain after photorefractive keratectomy.
RESULTS: Many drugs, both oral and topical, are used worldwide to control pain after photorefractive keratectomy, but no group has shown satisfactory pain control in all patients. The pilot study revealed that the pain was most severe in the first 24 hours after photorefractive keratectomy and declined to low levels thereafter. Topical anesthetics cause corneal complications when used excessively and for prolonged periods.
CONCLUSION: Pain after photorefractive keratectomy is most severe in the first 24 hours. Topical anesthetics would only be needed for this short time and would guarantee pain relief in all patients. We do not anticipate any corneal complications if the anesthetics are used for short times and under close medical supervision. [J Refract Surg. 1996,12:358-364.]
Quantitative Measurement of Corneal Haze After Myopic PRK
Authors: Chang Shou-Sung , Maurice David M , Ramirez-Florez Susana 
Published: April 2021

ABSTRACT
OBJECTIVE: To design and evaluate an instrument for the objective measurement of haze in rabbits after myopic PRK.
METHODS: A circular fluorescent lamp bulb projected light onto the cornea through a circular collimating aperture covered with an orange filter. The image was collected on a centrally mounted CCD camera and the profile of the haze circle along its horizontal diameter determined.
RESULTS: Haze circles were observed and quantitated. In the first weeks, they were donut-shaped, frequently with a central bright area, but later they became square-topped. The instrument reproduced measurements with an error of a few percentage points and showed good long-term stability. [J Refract Surg. 1996;12:412-416.]
Transient Central Corneal Steepening After Radial Keratotomy
Authors: Suzard Kurt A , Fundingsland Bradley R , Friedlander Miles 
Published: April 2021

ABSTRACT
Three case studies are presented illustrating topographic transient central steep island following radial keratotomy. Three stages are apparent: fîrst, a central corneal steepening; next, an overcorrection with exaggerated central flattening; and, finally, the final refractive correction. The steepening is probably caused by temporary midperipheral swelling of the cornea. [J Refract Surg. 1996;12:521-525.]
Diclofenac and Ketorolac in the Treatment of Pain after Photorefractive Keratectomy
Authors: Weinstock V Moss , Weinstock David J , Weinstock S Joseph 
Published: April 2021

ABSTRACT
BACKGROUND: Photorefractive keratectomy (PRK) can produce significant ocular pain. Topical diclofenac, a non-steroidal anti-inflammatory drug (NSAID), is effective in the reduction of this pain. This study compares a second NSAID, ketorolac, to diclofenac.
METHODS: This prospective matched-control study involved 102 eyes of 102 patients. Prior to PRK, patients were randomly assigned to receive ketorolac or diclofenac drops. At the first postoperative visit, a standardized questionnaire was used to assess the patient's average and peak levels of discomfort. In addition, the quantities of acetaminophen and codeine consumed were recorded.
RESULTS: The overall level of discomfort was 1.53 ± 0.64 for diclofenac and 1.88 ± 0.55 for ketorolac (scale: 0 to 4)(P=0.004). The diclofenac group reported a peak discomfort level of 2.0 ± 0.75 and the ketorolac group reported 2.3 ± 0.62 (P > 0.05). The diclofenac group consumed 2000 ±1150 mg of acetaminophen and 92 ± 54 mg of codeine whereas the ketorolac group consumed 2150 ± 940 of acetaminophen and 98 ± 50 mg of codeine (P > 0.05).
CONCLUSIONS: The differences in levels of peak discomfort, acetaminophen ingestion, and codeine ingestion, were not statistically significant. As compared to ketorolac, diclofenac resulted in a statistically significant lower mean overall discomfort. [J Refract Surg 1996;12:792-794].
Phototherapeutic Keratectomy for Granular and Lattice Corneal Dystrophies at 1.5 to 4 Years
Authors: Nassaralla Belquiz A , Garbus Jenny , McDonnell Peter J 
Published: April 2021

ABSTRACT
BACKGROUND: The capability of the 193-nm excimer laser to ablate the cornea and to remove opacities and various other corneal diseases in a procedure called phototherapeutic keratectomy (PTK) has been demonstrated. In this study we evaluated the long-term results of PTK for treatment of granular and lattice corneal dystrophies.
METHODS: Four eyes with granular or lattice corneal dystrophy were treated with a mean followup of 47.8 months (range, 36 to 58 months). Focal ablations of the central cornea with an ablation zone of 5.5 to 6.0 mm were performed. Ablation depth was 110 µt? in three eyes and 140 /on in one eye.
RESULTS: Removal of corneal opacities allowed for improvement in corrected visual acuity in all patients. Mean corneal thickness in the area of pathology decreased from 0.583 mm before surgery to 0.449 mm after surgery. Spherical equivalent of the manifest refraction measurements increased by a mean of +5.09 D. There were no major complications, but all patients developed slight haze. There was a hyperopic shift in three eyes.
CONCLUSION: Our long-term results suggest that PTK is a safe and effective alternative to penetrating and lamellar keratoplasty in patients with granular or lattice corneal dystrophies. [J Refract Surg 1996;12:795-800]
Laser in situ Keratomileusis to Correct Hyperopia from +4.25 to +8.00 Diopters
Authors: Göker Sinan , Er Hamdi , Kahvecioglu Cezmi 
Published: April 2021

ABSTRACT
OBJECTIVE: To evaluate the efficacy and predictability of laser in situ keratomileusis (LASIK) for hyperopia in a prospective study of 54 eyes of 29 patients.
METHODS: Before LASIK, 44 eyes (81.48%) had a spectacle-corrected visual acuity of 20/20 or better, and 54 eyes (100%) had 20/40 or better. Surgery was performed under topical anesthesia using the Keracor 116 excimer laser and Chiron automated corneal shaper. Mean follow-up was 19 months.
RESULTS: Mean baseline uncorrected hyperopia was +6.50 ± 1.33 D (range, +4.25 to +8.00 D). Mean uncorrected manifest spherical equivalent refraction was +0.44 ± 1.95 D at 18 months after LASIK. Twenty-one eyes (38.8%) were within ±0.50 D of emmetropia, 41 eyes (75.92%) were within ±1.00 D, and 47 eyes (87.03%) were within ±2.00 at 18 months after LASIK. Uncorrected visual acuity was 20/20 or better in eight eyes (14.81%) and 20/40 or better in 36 eyes (66.66%) 18 months after LASIK. Regression and undercorrection of more than 2.00 D occurred in seven eyes (12.9%) between the 3 and 6 month examinations; three of these seven eyes (42.8%) required retreatment to correct residual hyperopia. Three eyes (6.8%) lost two or more lines of spectacle-corrected visual acuity.
CONCLUSION: Excimer laser keratomileusis in situ with the Keracor 116 appears to be an effective and safe procedure to decrease low and moderate hyperopia, but the predictability of the procedure needs improvement. [J Refract Surg 1998;14:26-30]
Late Onset of Haze Associated with Viral Keratoconjunctivitis Following Photorefractive Keratectomy
Authors: Pineda Roberto , Talamo Jonathan H 
Published: April 2021

ABSTRACT
BACKGROUND: To report a newly recognized cause of late onset of corneal haze following photorefractive keratectomy (PRK).
METHODS: A 35-year old woman who underwent uneventful PRK and subsequently developed viral keratoconjunctivitis 1 year after treatment.
RESULTS: During resolution of the viral keratoconjunctivitis, the patient developed extensive central corneal subepithelial infiltrates and anterior stromal fibrosis in the PRK ablation zone. More than 1 year after the initial infection, the central subepithelial fibrosis persisted, complicated by myopic regression, central steep island on videokeratography, and loss of five lines of spectacle-corrected visual acuity. By the end of the second year after the infection, visual acuity had improved with disappearance of the central steep island on videokeratography. However, the myopic regression and subepithelial fibrosis remained.
CONCLUSION: Patients who undergo PRK may be at greater risk of visual loss following viral keratoconjunctivitis secondary to persistent subepithelial infiltrates and/or stromal fibrosis within the PRK treatment zone. [J Refract Surg 1998;14:147-1511
A Method for Examining Surface and Interface Irregularities after Photorefractive Keratectomy and Laser in situ Keratomileusis: Predictor of Optical and Functional Outcomes
Authors: Vinciguerra Paolo , Azzolini Marco , Radice Paola , Sborgia Maurizio , De Molfetta Vito 
Published: April 2021

ABSTRACT
PURPOSE: To develop a system for the examination of the ablated surface after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASER) and to correlate the surface regularity to the functional outcome.
METHODS: A Nidek Eas-1000 Anterior Eye Segment Analysis System was used to examine the ablated surface or the interface regularity immediately after PRK and LASIK. Eighty eyes were evaluated and divided into three study groups: group 1; regularity (18 eyes), group 2; mild irregularity (32 eyes), group 3; severe irregularity (30 eyes).
RESULTS: At 12 months postoperatively, group 1 (regularity) showed the best percentage of eyes with O haze (100%) and with a refraction ±1.00 D of piano (89%); group 2 (mild irregularity) 84% had 0 haze and 62% were ±1.00 D of piano; group 3 (severe irregularity) 27% had 0 haze and 47% were ±1.00 D of piano.
CONCLUSION: The patients with no postoperative irregularity had a sharply lower incidence of haze and a better refractive outcome with respect to piano, confirming the influence of ablation regularity on the results and the importance of this analysis in clinical practice. [J Refract Surg 1998,14:S204-S206]
Accuracy of Visual Correction in Photorefractive Keratectomy
Authors: Deva Jenny P 
Published: April 2021

ABSTRACT
PURPOSE: To investigate the accuracy of preoperative optical assessment and other factors that influenced the final visual outcome after photorefractive keratectomy (PRK).
METHODS: The records of 126 eyes from 54 male and 72 female eyes were studied retrospectively, ranging from 6 months to 3 years post-PRK. Refractive errors ranged from low to high myopia and astigmatism, and proper and careful preoperative selection of patients was made. A single standard ablation zone (AZ) of 6.00mm and transition zone (TZ) of 7.00mm was made in all cases.
RESULTS:The study population showed a high degree of accuracy in visual outcome. In simple myopia, 92.3% of female eyes and 84.1% of male eyes had a visual acuity of more than 6/9 or better. In myopia with astigmatism, 83.05% of female and 65.9% of male eyes had a visual acuity of 6/9 (20/40) or better. However, despite the residual myopia, whether with or induced astigmatism, post PRK visual acuity seemed to be less influenced by it, than as in the pre-PRK status.
CONCLUSION: This study showed an accuracy in visual outcome of >90% for females and >80% for males. The Nidek EC-5000 was satisfactory for its purpose. [J Refract Surg 1998;14:S215-S217]
Posterior Chamber Phakic Intraocular Lens for Hyperopia of +4 to +11 Diopters
Authors: Davidorf Jonathan M , Zaldivar Roberto , Oscherow Susana 
Published: April 2021

ABSTRACT
PURPOSE: To examine the efficacy, predictability, stability, and safety of posterior chamber phakic intraocular lens (IOL) implantation in eyes with high hyperopia.
METHODS: We analyzed the results of 24 eyes that received a posterior chamber hydrogel-collagen plate phakic IOL (Staar Collamer Implantable Contact Lens, ICL) for the correction of hyperopia with the goal of emmetropia. Mean follow-up was 8.4 months (range, 1 to 18 mo).
RESULTS: The mean preoperative spherical equivalent refraction was +6.51 ± 2.08 D (range, +3.75 to +10.50 D). Mean postoperative spherical equivalent refraction at last examination was -0.39 ± 1.29 D (range, +1.25 to -3.88 D), with 79% (19 eyes) within ±1.00 D and 58% (14 eyes) within ±0.50 D of emmetropia. Postoperative uncorrected visual acuity at last examination was 20/20 or better in 8% (two eyes) and 20/40 or better in 63% (15 eyes). A gain of two or more lines of spectacle-corrected visual acuity was seen in two eyes (8%) at last examination. One eye (4%) lost two or more lines of spectacle-corrected visual acuity due to progressive neovascular glaucoma initiated by early postoperative pupillary block.
CONCLUSION: Posterior chamber phakic IOL implantation with the Staar Collamer plate lens is an effective method for correcting high hyperopia. Large, patent iridotomies are important in hyperopic eyes to lower the risk of postoperative pupillary block. Improved phakic IOL power calculation formulas will refine predictability of refractive outcome. [J Refract Surg 1998;14:306-311]