bluuebunny/crossref_metadata_2025 huggingface dataset:
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]
Comparison of Videokeratoscope and Autokeratometer Measurements on Ellipsoid Surfaces and Human Corneas
Authors: Pardhan Shahina , Douthwaite William A
Published: April 2021

ABSTRACT

BACKGROUND: Various studies have compared the accuracy and repeatability of autokeratometers and videokeratoscopes using calibrated convex surfaces. We investigate the agreement between the Topcon KR-3500 autokeratometer and the EyeSys videokeratoscope on human corneas and calibrated convex surfaces.

METHODS: Measurements were obtained from 30 convex ellipsoidal buttons and 20 right eyes of 20 young normal human subjects. Vertex radius and pvalues were compared for the two instruments.

RESULTS: The two instruments showed excellent agreement on convex buttons. The human data showed no such relationship. For vertex radius, a good level of agreement was obtained only for surfaces whose p-values were near unity. Repeatability was also calculated and was shown to be better with the Topcon autokeratometer than with the EyeSys videokeratoscope. Editing the EyeSys data to encompass the same corneal area as that of the Topcon improved its repeatability, although it did not reach the level of the Topcon autokeratometer.

CONCLUSIONS: The Topcon autokeratometer and the EyeSys videokeratoscope showed reasonable agreement for surface topography on convex conicoidal plastic test buttons but not for human corneas. Alterations in the data-capture mechanisms of videokeratoscopes could improve their ability to accurately image paraboloidal surfaces. [J Refract Surg 1998;14:414-419]
Photorefractive Keratectomy for Hyperopia Using an Erodible Disc and Axicon Lens: 2-Year Results
Authors: Carones Francesco , Brancato Rosario , Morico Alessandro , Vigo Luca , Venturi Elisabetta , Gobbi Pier Giorgio
Published: April 2021

ABSTRACT

BACKGROUND: This paper presents the results over a 2-year follow-up of the first human trial of photorefractive keratectomy (PRK) for correction of hyperopia using an erodible disc excimer laser delivery system (Summit) coupled to an axicon lens.

METHODS: We treated 25 eyes of 21 patients for a mean correction of +3.38 ± 0.97 D (range, +1.00 to +4.00 D). The hyperopic correction was made using an erodible disc inserted on the laser optical pathway; an axicon lens was then used to create a blend transition zone. Eyes were evaluated at 1, 3, 6, and 12 months after surgery. For a smaller series of 11 eyes, we also present 24-month results.

RESULTS: Mean refractive error 1 month after treatment (25 eyes) was -2.35 ± 1.55 D (range, +1.00 to -6.50 D). Eight eyes (32%) had a spectacle-corrected visual acuity loss greater than 1 bine. Twelve months after treatment, mean spherical equivalent refraction was -0.47 ± 0.80 D (range, +1.25 to -2.25 D). Nineteen eyes showed an improvement (range, 3 to 8 lines) in uncorrected distance visual acuity and 23 showed improvement in uncorrected vision at reading distance (1 to 7 lines).

CONCLUSION: This technique proved effective in reducing hyperopia, but predictability must be demonstrated in a larger treatment group. Safety was confirmed by the absence of delayed reepithelialization and the absence of spectacle-corrected visual acuity loss greater than 1 line at 1 year after surgery. [J Refract Surg 1998;14:504-511]
Excimer Laser Lamellar Keratoplasty of Augmented Thickness for Keratoconus
Authors: Buratto Lucio , Belloni Sergio , Valeri Renato
Published: April 2021

ABSTRACT

PURPOSE: We describe a modified surgical technique for the treatment of patients in the early stage of keratoconus, when it is still possible to correct the astigmatic ametropia with contact lenses.

METHODS: Excimer laser lamellar keratoplasty of augmented thickness (ELLKAT) is a procedure in which a deep piano excimer laser ablation is done on the host cornea and a donor lamellar buttonwith or without an excimer laser refractive ablation on the posterior surface- is sutured into the recipient bed. In 12 of 20 eyes, the homoplastic button, which had parallel faces and was devoid of any dioptric power, was treated refractively on its stromal face with a Chiron Keracor 116 excimer laser to correct the axial and/or induced myopia present due to the weakened cornea.

RESULTS: The 8 eyes that received donor buttons without excimer laser ablation had improved spectacle-corrected visual acuity from a mean preoperative value of 20/100 (no eye saw 20/40 or better before surgery) to a mean postoperative value of 20/30 after 18 months. Mean refractive astigmatism was reduced from 4.84 ± 2.34 D to 1.00 1 0.46 D. Mean keratometric power was reduced from 56.75 ± 8.01 D to 44.21 ± 2.12 D. The associated mean spherical equivalent refraction was reduced from -4.75 to -3.00 D. Mean corneal thickness increased from 422.25 ± 83 µm preoperatively to 562.87 ± 57.81 µm postoperatively. The 12 eyes that received donor lamellar buttons treated with excimer laser also had improved spectacle-corrected visual acuity from a mean preoperative value of 20/100 to a mean postoperative value of 20/30 after 18 months. Astigmatism was reduced from a mean 4.84 ± 2.77 D to 1.66 ± 1.30 D; mean keratometric power was reduced from 56.08 ± 7.00 D to 45.31 ± 2.08 D; and the associated mean spherical equivalent refraction was reduced from -8.75 to -1.75 D. Corneal thickness increased from a mean 414.25 ± 64.75 µm preoperatively to 576.75 ± 28.23 µm postoperatively.

CONCLUSION: Compared to penetrating keratoplasty, excimer laser lamellar keratoplasty of augmented thickness for keratoconus has the advantage of preserving the host endothelium and of reducing the refractive error in keratoconus. [J Refract Surg 1998;14:517-525]
Differences in Keratocyte Apoptosis Following Transepithelial and Laser-scrape Photorefractive Keratectomy in Rabbits
Authors: Kim Woo-Jung , Shah Sujal , Wilson Steven E
Published: April 2021

ABSTRACT

BACKGROUND: Anterior stromal keratocyte cells undergo programmed cell death (apoptosis) in response to corneal epithelial injury. Keratocyte apoptosis may be an initiator of the corneal wound healing response that includes keratocyte proliferation and activation, as well as changes to the overlying epithelium, occurring following refractive surgical procedures such as photorefractive keratectomy (PRK). This study compares the effect of laser-scrape and transepithelial PRK on keratocyte apoptosis.

METHODS: Photorefractive keratectomy was performed in both eyes of 10 New Zealand white rabbits using the Summit Apex excimer laser. Surgery was performed using transepithelial PRK in one eye and laser-scrape PRK in the other. The central cornea was analyzed at 4 hours after surgery using a quantitative TUNEL assay that detects fragmented DNA characteristic of apoptosis. Hepatocyte growth factor (HGF) production by keratocytes was detected by immunocytochemistry.

RESULTS: Average apoptotic cells per 400X microscopic field determined by 2 independent masked observers were 0.9 ± 0.5 (scanning electron microscopy) and 0.2 ± 0.2 in the transepithelial PRK group compared with 5.1 ± 2.9 and 4.1 ± 3.2 in the laser-scrape group. The difference between the two groups was statistically significant for both observers (P < .05, ANOVA). HGF was detected within keratocytes throughout the corneal stroma. Less HGF was detected in the anterior stroma in the laser-scrape group at 4 hours after surgery, consistent with more anterior keratocyte apoptosis in this group.

CONCLUSIONS: Transepithelial PRK induced less anterior keratocyte apoptosis in rabbbits than laser-scrape PRK. This suggests that transepithelial PRK could be useful in preventing or minimizing refractive regression and subepithelial scarring. [J Refract Surg 1998;14:526-533]
The Call of the Sirens: Ethically Navigating the Sea of Nonvalidated Therapies
Authors: Grimmett Michael R , Sulmasy Daniel P
Published: April 2021

ABSTRACT

Medical research and innovation are vital to the advancement of medicine and, ultimately, benefit society and individual patients. However, the ethical principles of beneficence, respect for persons, and justice must guide the development and implementation of new practices. Ethical codes governing clinical practice and research already warn practitioners to avoid the use of nonvalidated practices outside of controlled clinical trials. Nonetheless, lack of compliance with these codes places many patients at risk for harm. Ophthalmologists, as well as all physicians, must recommit themselves to these ethical principles and codes and establish more vigorous peer-review methods to protect patients from nonvalidated practices that are implemented without a scientific basis. [J Refract Surgl998;14;559-566]
Experimental Circular Keratotomy for Correction of Corneal Astigmatism
Authors: Wijdh Robert H , van Rij Gabriël
Published: April 2021

ABSTRACT

PURPOSE: To investigate the effect of circular keratotomy depth and diameter on corneal astigmatism.

METHODS: High astigmatism was induced in 25 human donor eyes by an anterior radial 7-0 silk suture across the corneoscleral Iimbus. With a 6.0, 6.5, 7.0, or 7.5 mm trephine, a 0.3 mm deep circular incision was made in 20 donor eyes. In 5 donor eyes 5 circular incisions were made with a diamond knife set at 0.1, 0.2, 0.3, 0.4, and 0.5 mm depths.

RESULTS: The reduction of astigmatism between the 4 groups in which different trephination diameters were used showed no statistically significant difference (P>.1). The relationship between incision depth and reduction of astigmatism was statistically significant (P<001).

CONCLUSION: Artificially induced corneal astigmatism was reduced by a circular keratotomy in this donor eye model. Deeper incisions showed a greater effect. [J Refract Surg 1998;14:594-5961
Scleral Fixation for a Phakic Anterior Chamber Disc Intraocular Lens
Authors: Maggi Riccardo , Maggi Carlo
Published: April 2021

ABSTRACT

BACKGROUND: Angle-supported phakic anterior chamber intraocular lenses (IOLs) require a high degree of anterior vaulting, but this can cause an inadequate distance between the IOL and the cornea, especially during rubbing or squeezing of the eye.

METHODS: A vaultless implant was designed by anchoring 3 supple haptics through the anterior chamber into the sclera. Thus, a suspended rather than a wedged implant w$ts achieved.

RESULTS: The lens was implanted in 3 eyes of 2 patients in 1990. Good tolerance of the IOL was maintained over 7 years of follow-up.

CONCLUSION: A suspended anterior chamber phakic IOL maintains an adequate position with lack of bowing and shows promising results. J Refract Surg 1998;14:597-601]
Photorefractive Keratectomy in Eyes with Congenital Nystagmus
Authors: Siganos Dimitrios S , Evangelatou Kyriaki A , Papadaki Theokliti G , Katsanevaki Vikentia J , Dagos Athanassios I , Pallikaris Ioannis G
Published: April 2021

ABSTRACT

BACKGROUND: We report 2 eyes of 2 patients with nystagmus and myopia who underwent photorefractive keratectomy (PRK) to correct myopia.

METHODS: A 32-year old male patient with a baseline spectacle-corrected visual acuity of 20/40 had PRK with an Aesculap Méditée MEL 60 excimer laser with a suction ring system for correction of a spherical equivalent of -8.25 diopters (D). A 19-year old male patient with baseline spectacle-corrected visual acuity of 20/50 had PRK with an Autonomous Technologies T-PRK flying spot and tracking excimer laser to correct a spherical equivalent of -5.00 D.

RESULTS: Twenty-seven months after PRK, the operated eye of the 32-year old patient had an uncorrected visual acuity of 20/32 and a spectaclecorrected visual acuity of 20/25. Six months postoperatively, the operated eye of the 19-year old patient had uncorrected and spectacle-corrected visual acuity of 20/50.

CONCLUSION: Patients with nystagmus are eligible for PRK to correct their refractive error with these two laser systems. [J Refract Surg 1998;14:649-652]
Laser in situ Keratomileusis Interface Deposits
Authors: Hirst Lawrence W , Vandeleur Kevin W
Published: April 2021

ABSTRACT

BACKGROUND: A clinical investigation was undertaken to determine the origin of a brown interface deposit that developed in 15 eyes after laser in situ keratomileusis (LASEK).

METHODS: The LASBK procedure was evaluated and agents that were thought to be related to these brown deposits in the interface were eliminated sequentially. Eyes were observed after LASBK for presence or absence of the deposit.

RESULTS: Twenty-five consecutive LASES eyes in which a methylcellulose sponge was eliminated as a protector of the hinge developed no similar interface deposits.

CONCLUSION: The use of a dry methylcellulose sponge to protect the hinge may result in unexpected interface deposits after LASBK. [J Refract Surg 1998;14:653-654]
Laser in situ Keratomileusis to Correct Residual Myopia After Cataract Surgery
Authors: Ayala Maria J , Pérez-Santonja Juan J , Artola Alberto , Claramonte Pascual , Alió Jorge L
Published: April 2021

ABSTRACT

PURPOSE: To evaluate the effectiveness, predictability, and safety of laser in situ keratomileusis (LASIK) for correcting residual myopia after cataract surgery with intraocular lens implantation.

METHODS: Twenty-two eyes of 22 patients underwent LASIK for the correction of residual myopia after cataract surgery. LASIK was carried out using the Chiron Automated Corneal Shaper and the NIDEK EC-5000 excimer laser. In all eyes, the follow-up was 12 months.

RESULTS: Before LASIK, 1 eye (4.5%) had an uncorrected visual acuity of 0.5 or better; 12 months after LASIK, 10 eyes (45.4%) achieved this level of visual acuity and 0 eyes achieved 1.00 or better. Before LASIK, mean refraction was -2.90 ± 1.80 D; 12 months after LASIK it decreased significantly to 0.40 ± 0.60 D (P < .01). In 18 eyes (81.8%) at 12 months after LASIK, spherical equivalent refraction was within ±1.00 D of emmetropia; 11 eyes (50%) were within 0.50 D. No vision-threatening complications occurred.

CONCLUSION: LASIK with the Automated Corneal Shaper and Nidek EC-5000 excimer laser was an effective, predictable, stable, and safe procedure for correcting residual myopia after cataract surgery. No intraocular lens or cataract incision related complications occurred when LASIK was performed at least 3 months after phacoemulsification. [J Refract Surg 2001;17:12-16]
Smoothness of Ablation on Acrylic by Four Different Excimer Lasers
Authors: Argento Carlos , Valenzuela Gonzalo , Huck Hugo , Cremona Gustavo , Cosentino Maria Jose , Gale Maria Fernandez Ruiz
Published: April 2021

ABSTRACT

PURPOSE: There are many different excimer laser devices available for photoablative refractive surgery. Smoothness of ablation may vary with different excimer lasers systems.

METHODS: Ablations were performed on polymethylmethacrylate (PMMA) plates of 8 x 4 x 0.5 cm, with four different excimer lasers: VISX-Star, Coherent Schwind Keratom I/II, Chiron Technolas Keracor 117C (Plano Scan), and the Nidek EC-5000, to determine and compare the homogeneity and smoothness of the surface. Ten -3.00 D samples, ten -6.00 D samples, and ten -0.00 D samples were ablated with each laser. The PMMA discs were examined with optical microscopy, documented by photographs, and each sample was measured quantitatively using a Hommel-Werkel rugosimeter. We used the same PMMA material throughout.

RESULTS: Statistically significant differences in smoothness were found between the Chiron Technolas 117C and the VISX-Star, Nidek and VISX-Star, and Coherent Schwind and VISX-Star in the homogeneities achieved by ablating -3.00 D. Ablations of -6.00 D resulted in homogeneities that were statistically significantly different: Chiron Technolas 117C with the other three devices, the Nidek EC-5000 with the VISX-Star, and the Coherent-Schwind with the VISX-Star. In the ablations for -9.00 D, statistically significant differences in homogeneity were found between the Chiron Technolas 117C and Nidek, between the Chiron and VISX-Star, between the Coherent Schwind and VISX-Star, and between the Nidek and VISX-Star. The laser with the scanning spot system was smoother.

CONCLUSION: Scanning spot technology produced smooth ablations even up to -9.00 D. [J Refract Surg 2001;17:43-45]
Comparison of Laser in situ Keratomileusis and Photorefractive Keratectomy for the Correction of Myopia of -6.00 Diopters or Less
Authors: Tole Derek M , McCarty Daniel J , Couper Terry , Taylor Hugh R
Published: April 2021

ABSTRACT

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) compared to photorefractive keratectomy (PRK) for the correction of low or moderate myopia (-0.50 to -6.00 D) at 6 months after surgery.

METHODS: The study population comprised a non-randomized consecutive series of 622 eyes of 392 patients who were treated with the Nidek EC-5000 excimer laser. LASER was performed using the ACS Chiron microkeratome on 314 eyes and surface PRK on 308 eyes. All patients were treated using a standard protocol, then assessed at 1, 3, and 6 months postoperatively.

RESULTS: Forty-four percent of the LASIK group and 67% of the PRK group attended their 6-month examination. Eighty percent of patients (111 eyes) after LASEK and 65% (136 eyes) after PRK had an uncorrected visual acuity of 20/20 or better. Spherical equivalent refraction was within ±0.50 D of intended refraction in 78% (109 eyes) for LASEK and 82% (170 eyes) for PRK. Loss of two more lines of best spectacle-corrected visual acuity at 6 months occurred in 1.4% (2 eyes) of the LASEK group and 1.0% (2 eyes) of the PRK group.

CONCLUSION: At 1 month follow-up, the percentage of eyes that achieved 20/20 uncorrected visual acuity was greater in the LASEK group than in the PRK group. At 6 months, visual and refractive outcomes of LASEK and PRK were similar. Although flap related complications occurred only after LASEK, the overall risk of loss of best spectacle-corrected visual acuity was not significantly greater than for PRK. [J Refract Surg 2001;17:46-54]
Surgical Treatment of Keratoconus at the Turn of the 20th Century
Authors: Sekundo Walter , Stevens Julian D
Published: April 2021

ABSTRACT

PURPOSE: This paper reviews surgical modalities for treatment of keratoconus at the threshold of the 20th century.

METHODS: All ophthalmic literature from 1895 until 1925 in English and German, available at the library of the Institute of Ophthalmology, London, United Kingdom, was studied with respect to this topic.

RESULTS: Three thermal procedures were described; galvanocauterization with perforation, without perforation, and a non-contact application of heat to the corneal apex. Radial extension of a thermal burn to correct the minus cylinder represented a further modification. Excision of the conical area was suggested either as a lamellar dissection or as a full thickness trephination. Incision of the cone appeared to be less popular. In staged procedures, a combination of galvanocauterization, splitting of the cornea, conjunctival flap, and a subsequent optical iridectomy were applied.

CONCLUSION: The treatment of keratoconus 100 years ago used refractive surgery to improve visual function by modifying corneal shape. [J Refract Surg 2001;17:69-73]
Preliminary in vitro Study of the Histological Effects of Low Fluence 193-nm Excimer Laser Irradiation of Corneal Tissue
Authors: Al-qahtani Jerman M , McLean Ian W , Weiblinger Richard P , Ediger Marwood N
Published: April 2021

ABSTRACT

PURPOSE: To determine if moderate numbers of low fluence, 193-nm excimer laser pulses modify or damage the corneal stroma.

METHODS: The corneal epithelium of fresh bovine eyes was scraped off and the exposed stroma was irradiated with 200 low fluence laser pulses from an argon fluoride excimer laser. This process was performed on five eyes each at two laser fluences, 10 mJ/cm
p 2
and 30 mJ/cm
p 2
. The ten irradiated and three control (unirradiated) corneas were sectioned and studied by electron microscopy. The maximum and minimum thickness of the anterior layer of randomly oriented collagen fibers was measured using electron microscopy.

RESULTS: The mean maximum thickness of the anterior randomly oriented layer of collagen was 1.23 ± 0.45 µm in the control corneas, 0.67 ± 0.32 µm in the corneas irradiated at 10 mJ/cm
p 2
, and 0.10 ± 0.12 µm in the corneas irradiated at 30 mJ/cm
p 2
. The mean thickness of corneal stroma removed was 0.7 µm at a fluence of 10 mJ/cm
p 2
and 1.1 µm at a fluence of 30 mJ/cm
p 2
. A thin, electron-dense pseudomembrane was present at both fluences.

CONCLUSION: We report removal of bovine corneal stroma at 10 mJ/cm
p 2
-below the previously reported ablation threshold of 20 mJ/cm
p 2
. [J Refract Surg 2001;17:105-109]
Laser in situ Keratomileusis for the Correction of Hyperopia From +1.25 to +5.00 Diopters With the Technolas Keracor 117C Laser
Authors: Rashad Khaled M
Published: April 2021

ABSTRACT

PURPOSE: To assess the efficacy, predictability, stability, and safety of laser in situ keratomileusis (LASIK) in patients with hyperopia and to evaluate the visual and refractive results of the procedure.

METHODS: LASIK was performed on 85 eyes of 53 patients for correction of hyperopia, with a preoperative mean manifest spherical equivalent refraction of +3.31 ± 0.69 D (range, +1.25 to +5.00 D) and mean refractive astigmatism of +0.91 ± 1.06 D (range, 0 to +3.00 D). The Carriazo-Barraquer (Moria) manual microkeratome was used to create the corneal flap, and laser ablation was performed using the Technolas Keracor 117C excimer laser with an ablation zone diameter of 6.0 mm and a transition zone diameter to 9.0 mm. Follow-up was 12 months for all patients.

RESULTS: Refraction was stable by 3 months after surgery. At 1 year after LASIK, the mean manifest spherical equivalent refraction was +0.43 ± 0.57 D (range, -1.25 to +2.00 D) and refractive astigmatism was reduced to a mean of 0.36 ± 0.30 D (range, 0 to 1.00 D). Fifty-two eyes (61.2%) had a manifest spherical equivalent refraction within ±0.50 D of emmetropia, and 76 eyes (89.4%) were within ±1.00 D. Uncorrected visual acuity was 20/20 in 21 eyes (24.7%) and 20/40 or better in 79 eyes (92.9%). Spectacle-corrected visual acuity was reduced by two lines in one eye (1.2%) and improved by two lines in five eyes (5.9%). There were no significant complications.

CONCLUSION: LASIK was an effective, safe, and predictable procedure for the correction of hyperopia up to +5.00 D and hyperopic astigmatism up to +3.00 D with the Technolas Keracor 117C excimer laser. The large size of the corneal flap obtained by the Carriazo-Barraquer (Moria) manual microkeratome facilitated laser ablation entirely in the exposed corneal stromal bed. [J Refract Surg 2001;17:113-122]
Laser in situ Keratomileusis: Three Unexpected Complications
Authors: Rosa Daniele Aron
Published: April 2021

ABSTRACT

PURPOSE: To report unexpected outcomes in three patients after uneventful laser in situ keratomileusis (LASEK) performed using the Nidek EC-5000 excimer laser and the Hansatome microkeratome (Bausch & Lomb Surgical).

METHODS: LASIK was performed with the Nidek EC-5000 excimer laser and the Hansatome microkeratome (Bausch & Lomb Surgical) in three patients.

RESULTS: In three patients, unexpected outcomes were observed. One patient treated for -3.00 D of myopia presented with a central island. One patient treated for +2.00 D (+1.00 x 90°) of hyperopia in both eyes ended up emmetropic in one eye and overcorrected in the fellow eye. The third patient with -12.00 D (-2.00 x 180°) of myopia was treated as -8.60 -1.00 x 180° and at last examination was +4.00 D. During these sessions, all other patients treated were within ±0.50 D of emmetropia.

CONCLUSION: After LASIK with the Nidek EC-5000 excimer laser and the Hansatome microkeratome (Bausch & Lomb Surgical), unexpected outcomes may still occur, despite controlling all the usual variables. [J Refract Surg 2001;17(suppl): S177-S179]
Decentration After Refractive Surgery
Authors: Vinciguerra Paolo , Camesasca Fabrizio I
Published: April 2021

ABSTRACT

PURPOSE: To examine factors useful in evaluation of suspect decentration after refractive surgery.

METHODS: We evaluated 148 cases (eyes) referred to us for recentering procedures by review of information obtainable by evaluation of pupil position, corneal topography, and corneal curvature gradient.

RESULTS: Only a minority of eyes (n=5, 3.4%) were truly decentered; in the remaining majority a high dioptric grathent with consequent focal scarring was present (n=107, 72.3%). In 28 eyes (18.9%), a drifting of the eye during treatment was responsible, and in eight eyes (5.4%), a central island was observed.

CONCLUSIONS: Proper corneal topographical diagnosis reduces the risk of improperly suspecting decentration, and for most cases, smoothing of the central cornea is a simple and efficacious solution. Recommendations for the prevention of decentration include proper patient positioning, special care in treating high myopes, preoperative check of pupil displacement nasally, evaluation of preoperative map with detection of high temporal curvature grathent, and use of the cross-cylinder technique in the treatment of astigmatism. [J Refract Surg 2001;17(suppl):S190-S191]
Clinical Results After Subepithelial Photorefractive Keratectomy (LASEK)
Authors: Kornilovsky Igor M
Published: April 2021

ABSTRACT

PURPOSE: To study the results of photorefractive keratectomy (PRK) after creation of an epithelial flap and replacement of the flap after ablation (LASER).

METHODS: PRR was performed with the Nidek EC-5000 excimer laser. The technology of subepithelial PRK was developed in experiments in vitro in 10 pig eyes and six human eyes. The experiments in vivo were carried out in eight eyes of four rabbits. In patients, subepithelial PRK was carried out in 12 eyes with high myopia, best spectaclecorrected visual acuity of 20/30 and below. LASLK, ordinary PRR, or transepithelial PRK were performed in the second eye to act as a controL

RESULTS: The basic steps of subepithelial PRR include creation of an epithelial flap, refractive ablation, and subsequent repositioning of the epithelial flap. In the clinical trial, creation of an epithelial flap was easy in five (41.7%) eyes, moderate in four (33.3%) eyes, and difficult in three (25.0%) eyes. No pain occurred in six (50%) eyes, some discomfort in four (33.3%) eyes, and pain in two (16.7%) eyes. After subepithelial PRK, visual and refractive results were similar with both LASLK and PRK The common components of ordinary PRK, transepithelial PRK, and subepithelial PRK are removal of Bowman's layer and epithelium. The advantages and disadvantages of subepithelial PRR are considered.

CONCLUSION: Subepithelial PRR (LASER) has the potential for widespread use in clinical practice, but further development of special instruments and techniques would be helpful. [J Refract Surg 2001;17(suppl):S222-S223]