bluuebunny/crossref_metadata_2025 huggingface dataset:
Topical Diclofenac Treatment Prior to Excimer Laser Photorefractive Keratectomy in Rabbits
Authors: Szerenyi Karin , Wang Xun Wei , Lee Martha , McDonnell Peter J
Published: April 2021

ABSTRACT

PURPOSE: This study sought to determine whether pre- and posttreatment with topical diclofenac sodium 0.1% eye drops suppresses corneal inflammation after 193-nanometer excimer laser corneal ablation more effectively than does posttreatment alone.

METHODS: Eight rabbits were divided into four groups. Animals in group I were treated with topical diclofenac every half hour for 2 hours prior to photorefractive keratectomy; treatment was continued every hour for 3 hours after the ablation. Group Il animals, used as controls, were treated with the diclofenac vehicle according to the same schedule. The third group (III) received diclofenac topically only after the excimer laser ablation. The fourth group (IV) consisted of normal corneas from these same animals. At 3 hours after ablation, prostaglandin E? (PGE2) levels were measured in the corneas ana leukocytes were quantified.

RESULTS: Treatment with topical diclofenac significantly reduced levels of PGE2 compared to treatment with the vehicle (p = .024). Presurgical treatment with topical diclofenac did not result in greater suppression of PGE2 than did posttreatment alone (5.72 ± 0.91 pg/m L versus 5.79 ± 1.29 pg/mL). Similarly, there was a significant inhibition of leukocyte invasion in the diclofenac treated corneas (I vs II: ? = .019, ill vs II: ? = .024), but no statistically significant difference between pretreatment and posttreatment alone groups (I vs III: P = .72).

CONCLUSIONS: Topical administration of diclofenac reduces the release of PGE2 and the migration of polymorphonuclear leukocytes in the rabbit cornea 3 hours after 193-nanometer excimer laser ablation. However, pretreatmenf of the cornea, starting 2 hours prior to laser surgery, does not seem to offer advantages over postablation treatment in this animal model. Refract Corneal Surg. 1993;9:437-442.)

RÉSUMÉ

INTRODUCTION: Nous voulions étudier comparativement l'inflammation cornéenne dans les yeux traités avec diclofenac sodium avant et après kératectomie photorefractive au laser excimer 193 nm avec yeux traités uniquement en postopératoire.

MÉTHODES: Huit lapins furent divisés en 4 groupes. Les animaux du groupe I furent traités avec les gouttes de diclofenac toutes les 30 minutes pendant deux heures avant la kératectomie photorefractive et toutes les heures pendant trois heures post-opérativement. Le deuxième groupe servait de cas témoin, traité seulement avec le véhicule. Le troisième groupe recevait diclofenac uniquement en post-opératoire. Le quatrième groupe était constitué des cornées normales de ces animaux mêmes. Trois heures après la chirurgie, les niveaux de prostaglandin E2 (PGE2) furent mesurés et le nombre de leucocytes compté.
Arcuate Transverse Keratotomy for Astigmatism Followed by Subsequent Radial or Transverse Keratotomy
Authors: Price Francis W , Grene R Bruce , Marks Ronald G , Gonzales Jill S
Published: April 2021

ABSTRACT

BACKGROUND: We studied the safety and efficacy of arcuate transverse keratotomy performed for the primary correction of naturally occurring corneal astigmatism.

METHODS: A multicenter, prospective evaluation of one-stage arcuate transverse keratotomy was conducted in 160 eyes with 1.00 to 6.00 diopters (D) of naturally occurring astigmatism. Vector analysis was used. After 1 month, those eyes that needed further refractive surgery received radial keratotomy for myopia and second- stage arcuate transverse keratotomy for residual astigmatism.

RESULTS: Mean preoperative refractive cylinder was 2.80 D. At 1 month, the vector-corrected change was 2.30 D. Eighty-eight (61%) eyes had at least 1.00 D of residual refractive cylinder and 24 (17%) had at least 2.00 D. Eyes undergoing a second surgery averaged 1.60 D of vector-corrected effect, for a total effect of 2.90 D from both surgeries, indicating the astigmatic refractive effects were not additive. Eyes that had radial keratotomy alone as the second surgery demonstrated a similar change in refractive cylinder as eyes that had both radial and transverse keratotomies. Two eyes lost two lines of spectacle-corrected visual acuity, 29 eyes lost one line, 84 showed no change, and 26 eyes improved one line.

CONCLUSION: Arcuate transverse keratotomy reduced refractive astigmatism. Both overcorrection and undercorrection were common. Complications were infrequent but occasionally caused significant irregular astigmatism. Arcuate transverse keratotomy appears to be a safe procedure with few complications. [J Refract Surg. 1996;12:68-76.]
Anterior Chamber Flare After Photorefractive Keratectomy
Authors: Tomas-Barberan Santiago , Fagerholm Per
Published: April 2021

ABSTRACT

BACKGROUND: The inflammatory reaction produced after excimer photorefractive keratectomy (PRK) remains to be clarified. In this study, we measured flare in the anterior chamber after excimer PRK as an indirect sign of postoperative inflammation.

METHODS: Flare was measured in 25 eyes with a laser flare meter (Kowa FM 500) before and after excimer laser PRK. The eyes were divided in two groups: 1-week and 1-month follow-up groups. All eyes received topical 0.1% dexamethasone drops postoperatively.

RESULTS: The 95% confidence interval for the difference in flare between the operated and fellow eyes was 3.23 ± 1.81 at day 5 and 2.20 ± 2.02 at day 12 after surgery in the 1-month group and 6.50 ± 2.51 at day 2 and 2.12 ± 0.89 day 5 after the procedure in the 1-week group, thus showing a statistically significant elevation in flare after PRK (P<0.05 ). A statistically significant correlation between the depth of the stromal ablation and the flare elevation 12 days after PRK in the 1-month group was shown.

CONCLUSIONS: There was significant increase in anterior chamber flare after PRK, although considerable individual variation occurred. [J Refract Surg. 1996;12:103-107.]
Holmium:YAG Laser Thermokeratoplasty for Astigmatism in Rabbits
Authors: Lim Key Hwan , Kim Woo Jung , Wee Won Ryang , Shin Dong Eul , Lee Jin Hak , Chang Bong Leen
Published: April 2021

ABSTRACT

BACKGROUND: Holmium:YAG laser thermokeratoplasty has generated considerable interest as a technique for correcting hyperopia. In this study, the effect of holmium:YAG laser on inducing astigmatism according to application patterns was evaluated.

METHODS: An experimental study based on the results of astigmatic holmium:YAG laser thermokeratoplasty using the Summit OmniMed laser system (Summit Technology Inc, Waltham, Mass) in 36 rabbit eyes is presented. We divided the rabbits into four groups: arcuate, reverse arcuate, linear, and control group according to application patterns. All rabbits were followed for 3 months and cycloplegic refractive measurements were carried out.

RESULTS: The average surgically induced astigmatism was 1.86 diopters (D) for the arcuate group, 2.93 D for the reverse arcuate group, and 1.31 D for the linear group. No significant complications related to the operation were noted.

CONCLUSION: The reverse arcuate pattern of holmium:YAG laser thermokeratoplasty is most effective in inducing astigmatism in rabbits. [J Refract Surg. 1996;12:190-193.]
Tracker-Assisted Photorefractive Keratectomy for Myopia of -1 to -6 Diopters
Authors: Pallikaris loannis , McDonald Marguerite B , Siganos Dimitrios , Klonos Gregory , Detorakis Stathis , Frey Randy , Downes Richard , Gauthier Charline A
Published: April 2021

ABSTRACT

BACKGROUND: The Autonomous Technologies T-PRK® (Tracker-assisted Photorefractive Keratectomy) excimer laser system uses a small beam scanner that allows flexibility in the ablation pattern that is applied to the cornea and incorporates a sophisticated LADARVision® eye tracker that is capable of following saccadic movements. This paper describes the first clinical results on sighted eyes for the correction of low myopia.

METHODS: Forty-two normal sighted eyes of 42 patients were treated for spherical myopia between -1.00 diopters (D) and -6.00 D with 6 mm ablations. Visual acuity, refractive error, contrast sensitivity (with and without glare), corneal haze, endothelial cell density, and patient satisfaction were measured.

RESULTS: Mean manifest refraction was -0.39 D ± 0.68 D at 1 month with regression to -0.94 D at 3 months and -1.05 D at 6 months. At 6 months, 5 (20%) eyes were ± 0.50 D and 14 (56%) eyes were ± 1.00 D. Consistent with this undercorrection and regression, uncorrected visual acuity (UCVA) of 20/20 and 20/40 or better was achieved by 10 (40%) and 34 (85%) eyes at 3 months and 16 (40%) and 17 (68%) eyes at 6 months. None of the eyes lost 2 or more lines of spectacle corrected visual acuity. Corneal haze was graded as 1/2 trace or less in 89% to 100% of eyes at all intervals. There was no loss of endothelial cells (mean ± SD cell density centrally: preop 3115 ± 322 and 6 months 3220 ± 333) and contrast sensitivity recovered to baseline levels at 3 months.

CONCLUSIONS: The Autonomous Technologies T-PRK® excimer laser system is safe and effective for the reduction or correction of myopia from -1.00 D or -6.00 D. The refractive results may be improved by adjusting the calibration to reduce the undercorrection and by instituting use of topical corticosteroids on an individual basis for those who regress. [J Refract Surg. 1996;12:240-247.]
Double Zone PRK for High Myopia
Authors: Aktunç Turgay , Aktunç Rengin , Bahçecioglu Halil
Published: April 2021

ABSTRACT

INTRODUCTION: Although excimer laser PRK is our operation of choice for treating myopia, the correction of myopia exceeding -8.00 dpt is still a challenge as this procedure requires a deeper keratectomy. Therefore a double zone treatment may be beneficial to reduce ablation depth.

METHODS: Twenty-one eyes with myopia between -8.00 dpt and -14.00 dpt were included in this study. Twelve eyes were treated 60% of myopia by 5 mm zone and the remaining 40% in a 4 mm zone in the same session (Group 1).

RESULTS: Nine eyes achieved 60% of the desired correction treated with a 4 mm zone whereas 40% correction was achieved in a 5 mm zone (Group 2). No significant difference in postoperative healing, pain, hyperopic shift, myopic regression and haze was observed at the end of the mean follow-up time (10.4 months) but photophobic complaints were less in Group 2. Best corrected visual acuity did not decrease significantly.

CONCLUSIONS: Double zone treatment seems to be an interesting method for treating moderate to high myopia. [J Refract Surg. 1996;12:S271-S273.]
Excimer Laser Phototherapeutic Keratectomy for Corneal Opacities and Recurrent Erosion
Authors: Kozobolis Vasilios P , Siganos Dimitrios S , Meladakis George S , Pallikaris Ioannis G
Published: April 2021

ABSTRACT

BACKGROUND: Phototherapeutic keratectomy (PTK) has been used to treat superficial corneal opacities, as well as the recurrent corneal erosion syndrome.

METHODS: We performed PTK 6 eyes of 6 patients to treat corneal opacities, and in one eye of another patient to treat recurrent corneal erosion syndrome. Opacities were caused by a healed corneal ulcer, herpetic keratitis, band keratopathy, corneal burn, corneal dystrophy, and an excised pterygium. The follow-up period ranged from 2 to 6 months.

RESULTS: Corneal clarity improved to variable degrees in all eyes with corneal opacities. There was no recurrence in the Recurrent Corneal Erosion Syndrome. A hyperopic shift was observed in 2 eyes.

CONCLUSIONS: PTK appears to be an effective alternative to penetrating keratoplasty in patients with selected anterior stromal opacities can treat the Recurrent Corneal Erosion Syndrome. [J Refract Surg. 1996;12:S288-S290.]
Arcuate Transverse Keratotomy With a Mechanical Arcutome Based on Videokeratography
Authors: Pallikaris Ioannis G , Xirafis Michael E , Naoumidis Leonidas P , Siganos Dimitrios S
Published: April 2021

ABSTRACT

Corneal topographic hardware was used to develop software analysis for configuration and localization of relaxing astigmatic arcuate incisions. The software is based on the assessment of the results of corneal topographic measurements, performed by the EyeSys Corneal Analysis System. Data assessment includes: A) plotting the dioptric power curves along the circular zones that may be considered appropriate for the placement of arcuate cuts; B) determination of the astigmatic axes position in each selected arc; and C) finding the position of points with the mean dioptric power value between the neighboring astigmatic axes which determine the proposed placement of the arcuate incisions. The new instrument developed for arcuate astigmatic keratotomy includes the algorithm for incision(s) disposition, the software, and the arcutome. [J Refract Surg. 1996;12:S296-S299.]
Effect of Incision Direction on Refractive Outcome After Radial Keratotomy
Authors: Flanagan Gerald W , Binder Perry S
Published: April 2021

ABSTRACT

PURPOSE: Radial keratotomy incisions can be made centripetally or centrifugally. The benefits and effects of both techniques have been disputed since American surgeons began performing RK in the late 1970s. We examined the RK database of a single surgeon to determine if incision direction was associated with refractive outcome.

METHODS: Stepwise regression was employed to select the important predictors of refraction change in the population. In addition to incision direction, variables eligible for entry into the model were optic clear zone diameter, incision number, patient age, corneal curvature and planned incision depth.

RESULTS: All variables except for planned incision depth and corneal power entered the model.

CONCLUSIONS: The results were consistent with previous investigations that found incision number, optic clear zone diameter and patient age important predictors of outcome. We also found incision direction to be a significant predictive variable with centripetal incisions decreasing myopia 0.6 diopters more than centrifugal incisions. [J Refract Surg. 1996;12:S299-S301.]
A New Scleral Suction Trephine for Retrieval of Corneoscleral Donor Tissue
Authors: Vrabec Michael P , Fan Nancy I , Dahl Patricia , Florakis George J
Published: April 2021

ABSTRACT

BACKGROUND: Removal of donor corneo-scleral shell from a cadaver, leaving the remainder of the eye in place, has become a poplular technique. Manual removal can result in excessive trauma to the corneal endothelium or an uneven scleral rim.

METHODS: We describe a new technique for corneal retrieval using a sceral suction trephine.

RESULTS: The scleral suction trephine was cut evenly in our eyebank study. There was no additional trauma to the endothelium and the scleral rim was regular.

CONCLUSION: Suction trephination of the sclera in retrieval of corneal donor tissue appears to be safe and effective. [J Refract Surg. 1996;12:S302-s303.]
Closed-System Technique for Implantation of Iris-Supported Negative-Power Intraocular Lens
Authors: Krumeich Jorg H , Daniel Jan , Gast Robert
Published: April 2021

ABSTRACT

BACKGROUND: The iris-supported claw lens can reversibly correct a wide range of ametropia and aniseikonia with excellent predictability and stability. However, concerns regarding its potential harm to the corneal endothelium have prevented its widespread use. Our experience with the closedsystem surgical technique and the spreader device used in 180 cases between 1987 and 1993 has led us to conclude that potential complications are more likely due to the technique of implantation rather than to the properties of the lens itself.

METHOD: We conducted a prospective study of 35 eyes of 20 consecutive patients (mean age, 38 years; range, 21 to 55 years) operated on between August 1993 and August 1994. Preoperative spherical equivalent refractions ranged from -6.00 to -21.25 diopters (D) (mean, -12.50 D). Follow up was 6 months (86% of eyes) to 1 year (57% of eyes). Spectacle-corrected visual acuity and endothelial cell density were measured prior to, and I1 6, and 12 months following lens implantation. All data were analyzed using the paired t-test.

RESULTS: Mean endothelial cell density dropped insignificantly (p>.10): by 1.22% at 1 month (n=34), by 2.25% at 6 months (n=27), and by 1.21% at 12 months (n=18).

Spectacle-corrected visual acuity increased significantly (p<.001): from a mean of 0.61 preoperatively to 0.77 at 1 month, 0.84 at 6 months, and 0.93 at 12 months postoperatively. At 12 months, 15 eyes (75%) had a refraction within ±0.50 D, 19 eyes (95%) within +1.00 D, and 20 eyes (100%) within +2.00 D of emmetropia.

CONCLUSIONS: Our results suggest that the closed-system approach using the spreader device allows safe implantation of the Worst iris-supported claw lens. [J Refract Surg. 1996;12:334-340.]
Photorefractive Keratectomy for Myopia With a 6-mm Beam Diameter
Authors: Shah Shetal I , Hersh Peter S
Published: April 2021

ABSTRACT

BACKGROUND: Earlier studies have reported clinical outcomes for up to 2 years following photorefractive keratectomy (PRK) using a 5.0-mm treatment zone with the Summit excimer laser. We present results of PRK using a 6-mm ablation zone with the same laser.

METHODS: Forty-five eyes of 45 patients underwent excimer laser PRK for correction of myopia using a 6-mm excimer laser beam diameter. Attempted corrections ranged from 1.50 diopters (D) to 6.00 D. Data on outcomes of uncorrected visual acuity, spectacle-corrected visual acuity, predictability, corneal haze, subjective glare/halo effects, and patient satisfaction with the procedure were analyzed over a follow-up period of 6 months.

RESULTS: All patients obtained a postoperative uncorrected visual acuity of at least 20/40; 28 eyes (62%) achieved at least 20/20. Postoperative spectacle-corrected visual acuity was at least 20/20 in all patients; no patients lost more than one Snellen line of spectacle-corrected visual acuity. Twentyeight patients (62.2%) achieved within ±0.50 D of the attempted correction; 40 patients (84.4%) achieved within +1.00 D. Mean spherical equivalent refraction was -4.99 D preoperatively and +0.44 D at 1 month, +0.04 D at 3 months, and +0.09 D at 6 months. At 6 months, 40 eyes (88.9%) were graded as clear, 4 eyes (8.9%) as having trace subepithelial haze, and 1 eye (2.2%) as having mild subepithelial haze. The mean glare/halo index for all of the patients was 0.59 on a scale of 0 to 5. Mean subjective patient satisfaction was 4.68 (on the same scale).

CONCLUSIONS: Clinical outcomes following excimer laser PRK for myopia using a 6-mm treatment zone are encouraging. Postoperative subjective glare/halo were minimal, suggesting an optical advantage in using the larger ablation zone. [J Refract Surg. 1996;12:341-346.]
Corneal Asphericity and Its Implications for Photorefractive Keratectomy: a Mathematical Model
Authors: Patel Sudi , Marshall John
Published: April 2021

ABSTRACT

BACKGROUND: Several clinical trials investigating myopic excimer laser photorefractive keratectomy (PRK) report an initial change in refraction from myopia to hyperopia, followed by a gradual regression toward emmetropia and occasionally to recurrent myopia. We examined the effect of corneal shape on refraction following PRK for myopia using a mathematical model.

METHODS: We calculated the volume of corneal tissue removed by PRK for -3.00-diopter (D) and -6.00-D corrections with ablation diameters of 5 mm and 6 mm. For all the operating algorithms» the central region of the cornea was considered spherical. Mathematical models were developed based on calculations of the apical radius of the ablated cornea and the final refraction for a range of corneal asphericities. Baker's equation was used to model corneal asphericity.

RESULTS: The smaller both the ablation size and desired correction, the smaller the effect of corneal asphericity on the refractive outcome. While corneal asphericity can influence the immediate refraction after PRK, the maximum effect is unlikely to be greater than +0.75 D.

CONCLUSIONS: Corneal asphericity marginally affects the initial outcome of PRK. The effect will probably be offset by the healing response of the cornea. [J Refract Surg. 1996;12:347-351.]
Pilocarpine in the Management of Overcorrection After Radial Keratotomy
Authors: Laranjeira Eduardo , Buzard Kurt A
Published: April 2021

ABSTRACT

BACKGROUND: Induced hyperopia is a potential complication of radial keratotomy with few effective treatments. We report the results of a retrospective study to evaluate the effectiveness of pilocarpine in the treatment of eyes overcorrected by radial keratotomy.

METHODS: Sixteen eyes of 14 patients, from a consecutive pool of 200 eyes who underwent radial keratotomy, had hyperopia. The patients were subsequently treated with topical pilocarpine. The patients were treated from 3 to 14 weeks (mean, 8.2 weeks).

RESULTS: The mean time of diagnosis of hyperopia was 3 weeks after the surgery (range, 1 to 12 weeks). The mean spherical equivalent of the manifest (fogging) refraction was +1.92 diopters (D) (range, +0.75 D to +5.00 D) and the keratometric power ranged from 31.25 D to 41.00 D (mean, 36.05 D). Mean uncorrected visual acuity before the treatment with pilocarpine was 20/50. After the treatment with pilocarpine, the mean spherical equivalent refraction was -0.31 D (range, -1.75 D to +0.50 D). The mean keratometric power was 38.32 D (range, 34.87 D to 43.12 D), with a mean uncorrected visual acuity at 20/25. The patients were followed for 8 to 49 weeks after treatment without pilocarpine (mean, 21 weeks). The mean spherical equivalent refraction and keratometric readings after that period were -0.71 D (range, -2.25 D to +0.25 D) and 38.33 D (range, 36.12 D to 43.12 D), respectively. All eyes in this study had more than 1.00 D of reduction of hyperopia at the conclusion of the study.

CONCLUSION: Pilocarpine effectively reduced overcorrections after radial keratotomy. After termination of treatment, the steepening of corneal curvature was maintained. [J Refract Surg. 1996; 12:382-390.]
Photorefractive Keratectomy and Laser In Situ Keratomileusis for Myopia Between 6.00 and 10.00 Diopters
Authors: Helmy Sherif A , Salah Ayman , Badawy Tarek T , Sidky Ahmed N
Published: April 2021

ABSTRACT

BACKGROUND: Excimer laser photorefractive keratectomy (PRK) can be effective in correcting myopia up to -6.00 diopters (D). Between -6.00 D and *10.00 D, the procedure is considered less effective and safe because it has been associated with dense scar formation and a high rate of regression. We compared photorefractive keratectomy (PRK) in this group of myopes with excimer laser keratomileusis in situ (LASIK).

METHODS: Forty consecutive eyes with a manifest refraction between -6.00 and -10.00 D were treated with PRK using an ablation-zone diameter of 6 mm. Subsequently, 40 consecutive eyes were treated with LASIK under a hinged flap using an ablation-zone diameter of 5 mm. All procedures used a Summit OmniMed laser and were done by the same surgeon.

RESULTS: Preoperatively, 24 eyes (60%) undergoing PRK had 20/20 spectacle-corrected visual acuity; 1 year postoperatively, 20 (50%) had 20/20 vision uncorrected. Preoperatively, 13 eyes (33%) undergoing LASIK had 20/20 spectacle-corrected visual acuity; 1 year postoperatively, 24 (60%) could see 20/20 uncorrected. Sixteen (39%) PRK eyes had a spherical equivalent refraction within +1.00 D at 1 year; 20 (60%) eyes undergoing LASIK had a refraction within +1.00 D at that point. None of the eyes treated with LASIK developed corneal haze, while after PRK, 36 eyes (90%) developed haze (23 eyes [57%] +2 to +3).

CONCLUSION: LASLK under a hinged flap proved superior to PRK in treating myopia between -6.00 D and -10.00 D. [J Refract Surg. 1996;12:417-421.]
Laser In Situ Keratomileusis to Correct Myopia of -6.00 to -29.00 Diopters
Authors: Knorz Michael C , Liermann Andreas , Seiberth Volker , Steiner Holger , Wiesinger Bettina
Published: April 2021

ABSTRACT

BACKGROUND: Photorefractive keratectomy eau cause corneal scarring and visual loss in highly myopic eyes. We evaluated laser in situ keratomileusis (LASIK) because it has the theoretical advantage of preserving both the corneal epithelium and Bowman's layer.

METHODS: In a prospective study, LASIK was performed in 62 myopic eyes (42 patients) using the Automatic Corneal Shaper (Chiron Vision) and the Eeracor 116 excimer laser (Chiron Technolas). We measured refraction and visual acuity, and evaluated corneal topography (TMS 1) and corneal clarity after 4 to 8 weeks and 4 to 6 months.

RESULTS: Four- to 6-month follow up was completed in 51 eyes. The mean preoperative spherical equivalent refraction was -14.80 diopters (D) (range, -6.00 to -29.00 D). Postoperatively, the mean deviation from the target refraction was -1.70 D (range, -9.00 to +2.50 D) at 4 to 8 weeks and -1.90 D (range, -9.50 to 4-2.25 D) at 4 to 6 months. At 4 to 6 months, 19 eyes (37%) were within ±0.50 D of the target refraction, 24 (47%) within ±1.00 D, 33 (65%) within ±2.00 D, and 40 (78%) within ±3.00 D. From 4 to 8 weeks to 4 to 6 months, the mean regression of myopia was -0.20 D (0.50 D or less in 24 eyes [47%], 1.00 D or less in 32 [63%], and 2.00 D or less in 42 [82%]). In six eyes (12%), the stromal interface was not visible, in 38 (74%) it was barely visible, and in seven (14%) it was clearly visible. Corneal topography revealed only small variations in clear-zone gize and dioptric value, demonstrating a very stable correction 4 to 6 months postoperatively.

CONCLUSIONS: LASIK may be a safe and effective procedure to correct high myopia. Further research is required to develop satisfactory microkeratome technology, effective laser algorithms, and to determine long-term stability of refraction. [J Refract Surg. 1996;12:575-584.]
Comparison of Intersecting Trapezoidal Keratotomy and Arcuate Transverse Keratotomy in the Correction of High Astigmatism
Authors: Harto Miguel A , Maldonado Miguel J , Cisneros Angel L , Perez-Torregrosa Vicente T , Menezo José L
Published: April 2021

ABSTRACT

BACKGROUND: High astigmatism can be corrected using trapezoidal or arcuate transverse keratotomies. Videokeratography enables qualitative evaluation of the corneal topography.

METHODS: Fifty-five eyes of 41 patients presenting with high astigmatism after penetrating keratoplasty or naturally occurring astigmatism (mean, 6.29 diopters [D]; range, 3.00 to 16.00 D) underwent correction using either intersecting trapezoidal or arcuate transverse keratotomies. Corneal topographic maps were analyzed and classified into keratographic patterns. Mean follow up was 3 years (range, 1 to 6 years).

RESULTS: The mean net decrease in refractive astigmatism was 3.60 D (52.7% reduction). The flattening/steepening ratio was on average higher for intersecting trapezoidal keratotomy (7.26 for astigmatism after penetrating keratoplasty and 8.31 for naturally occurring astigmatism) than for arcuate transverse keratotomy (.98 in astigmatism after penetrating keratoplasty and 1.76 in naturally occurring astigmatism). Accordingly, intersecting trapezoidal keratotomy tended to produce a hyperopic shift in the spherical equivalent refraction, whereas arcuate transverse keratotomy generally preserved the spherical equivalent refraction (mean hyperopic shift, 2.65 and .56 D, respectively). The mean vector-corrected change of refractive astigmatism after intersecting trapezoidal keratotomy was 88.8% in naturally occurring (ra=21 eyes) and 70.3% in penetrating keratoplasty astigmatism (n= 13). Arcuate transverse incisions corrected on average 79.9% of naturally occurring (n=13) and 60.8% of penetrating keratoplasty astigmatism (w=8). Videokeratography showed the asymmetric bowtie pattern as the most frequent pattern for both procedures. Intersecting trapezoidal keratotomy was characterized by relatively higher incidences of polygonal and irregular patterns. Arcuate transverse incisions caused less wound healing defects and glare than intersecting trapezoidal keratotomy.

CONCLUSIONS: Both intersecting trapezoidal keratotomy and arcuate transverse incisions effectively reduced high naturally occurring astigmatism and astigmatism after penetrating keratoplasty. However, greater corneal surface irregularity and more complications were seen following intersecting trapezoidal keratotomy. Trapezoidal keratotomy should not be used unless a large decrease of myopia is needed, and then a nonintersecting technique is preferable. [J Refract Surg. 1995;12:585-594.]
Inferior Steepening is Associated with Thinning of the Inferotemporal Cornea
Authors: Colin Joseph , Sale Yves , Malet Florence , Cochener Beatrice
Published: April 2021

ABSTRACT

PURPOSE: Videokeratography has enabled detection of inferior steepening patterns in patients thereby designated as keratoconus suspects. Since no information about the corneal thickness of these eyes is available, we studied several patients with such patterns, and compared the corneal thickness of their eyes with that of normals.

METHODS: Three groups of patients who had undergone videokeratography were studied with ultrasonic pachymetry centrally and in four quadrants at the 3-mm clear zone: 44 eyes with true keratoconus, 23 eyes of individuals with inferior steepening of the cornea who were family members of patients with keratoconus; and 44 normal eyes never fitted with contact lenses. The corneal thickness of the eyes in the first two groups was then compared with that in the third using ANOVA and Student's t test.

RESULTS: Corneal thickness in the normal eyes and in those with inferior steepening was similar in all except the inferotemporal quadrant. In this quadrant, the corneas of the eyes with inferior steepening were thinner than those of the normal eyes: 544 ± 32 µm vs 581 ± 30 µm (p < .05)

CONCLUSION: Eyes with inferior steepening on videokeratography have thinner inferotemporal corneas than normal eyes. [J Refract Surg. 1996;12:697-699.]
Variability in Corneal Thickness Before, During, and After Radial Keratotomy
Authors: Terry Mark A , Ousley Paula J
Published: April 2021

ABSTRACT

BACKGROUND: Precision in radial keratotomy requires accurate pachymetry for safety and efficacy. We evaluated the location, timing, and extent of changes in corneal thickness between those determined by preoperative measurement in the clinic and those determined by pre-incision and post-incision measurement in the operating room.

METHODS: Sixty eyes of 37 patients had ultrasonic pachymetry measurements of the central and paracentral cornea taken in the clinic 20 minutes before each patient underwent radial keratotomy. The pachymetry was repeated intraoperatively immediately before and, in a subset of 17 eyes, immediately after incisions were made, and the readings were compared.

RESULTS: The thinnest of the four paracentral readings measured just prior to placing the radial keratotomy incisions was located temporally in 92% of the eyes and inferiorly in 8%. Corneas progressively thinned from clinic to surgery by an average of 7 ± 12 µm centrally and 10 + 18 µm temporally. Additional thinning of 13 ± 14 µm centrally and 22 + 23 µm temporally occurred during surgery.

CONCLUSION: The thinnest paracentral corneal region measured in an eye was not always located in the same quadrant preoperatively and intraoperatively. During the time of incision placement, significant corneal thinning had occurred at each incision site. Individual variations in corneal thickness between that measured preoperatively and that measured during surgery cautions against the use of clinic readings for diamond knife settings during radial keratotomy. [J Refract Surg. 1996;12:700-704.]
Hot Needle Thermal Keratoplasty to Correct Naturally Occurring Hyperopic Astigmatism
Authors: Charpentier Dominique Y , Bertel Franck , Duplessix Michel , Colin Joseph , Denis Philippe
Published: April 2021

ABSTRACT

OBJECTIVE: To study the safety, effectiveness, predictability and stability of sectoral thermal keratoplasty in the treatment of naturally occurring hyperopic astigmatism.

METHODS: Using Fyodorov's technique, sectoral controlled coagulations were applied on both sides of the flattest meridian in 12 eyes from eight patients with naturally occurring hyperopic astigmatism. Preoperative average refractive cylinder was +3,19 ± 1.13 diopters (D), and the mean spherical component was +0.71 ± 1.03 D. Mean follow-up time was 13.2 months.

RESULTS: Immediately after surgery, we observed a significant overcorrection in the treated meridian in all patients. Then, a gradual decrease of the refractive effect was noticed, since the average refractive astigmatism was +0.25 ± 1.23 D at 6 months and +1.15 ± 0.86 at 12 months after surgery. At 1 month after surgery, the mean shift in the cylinder axis was 83.75° ± 8.82° and 12.08° ± 12.33° at the 1-year examination. Uncorrected visual acuity was 20/40 or better in all patients 1 year after surgery. We did not observe severe corneal complications, such as irregular astigmatism or delayed epithelial wound healing.

CONCLUSION: Hot needle sectoral thermal keratoplasty appears to be safe and partially effective in reducing hyperopic astigmatism, but considerable postoperative regression may occur. [J Refract Surg 1996;12:705-708.]
Posterior Polymorphous Dystrophy Associated with Astigmatism and Amblyopia in Children
Authors: DeRespinis Patrick A , Norden Richard A , Rispoli Lauren C
Published: April 2021

ABSTRACT

BACKGROUND: Posterior polymorphous dystrophy has been described in the scientific literature as having more than a casual association with keratoconus in adults. We studied four consecutive children with posterior polymorphous dystrophy who had coexisting astigmatism. In our patients, the posterior changes appeared to be associated with the corneal astigmatism, as evidenced by videokeratography.

METHODS: Four consecutive cases of posterior polymorphous dystrophy in children were found over a 3-year period by one of the authors (PD). They presented with varying degrees of amblyopia in the eyes with the greater amount of posterior polymorphous dystrophy. Cycloplegic refractions and keratometry readings were performed . The more affected eyes had greater degrees of astigmatism, presumably causing the amblyopia. Whenever possible, the results were supplemented by confirmation by a corneal specialist, specular microscopy, slit-lamp photographs and videokeratography.

RESULTS: Greater asymmetry of posterior polymorphous dystrophy was associated with greater astigmatism in the more affected eye. When more astigmatic anisometropia was present there was a greater amblyopia. Videokeratography of one of the patients showed that an area of confluent blebs forming a crescent shape compared exactly with a steep cylinder along the same axis. With-the-rule astigmatism was associated with a more diffuse pattern of blebs.

CONCLUSION: Decreases in visual acuity in children with posterior polymorphous dystrophy may sometimes be due to an amblyopia caused by the astigmatism of asymmetric disease. [J Refract Surg. 1996;12:709-714.]
Topography of Rabbit Corneas after Photorefractive Keratectomy for Hyperopia Using Airborne Rotational Masks
Authors: Dierick Hans G , Van Mellaert Catherine E , Missotten Luc
Published: April 2021

ABSTRACT

PURPOSE: To determine the long-term outcome of photorefractive keratectomy (PRK) for hyperopia on the rabbit cornea using ablation profiles with a smooth transition zone.

METHODS: Two profiles were ablated by means of an excimer laser and rotational masks, each profile on four rabbit eyes. Corrections of +10 diopters (D) were planned in all operations. The right eye was treated with a 4-mm optical zone and a 2-mm transition zone (4-mm/8-mm profile), the left eye with a 4-mm ablation and a 1-mm transition zone (4mm/6-mm profile). Corneal topography was measured with an EyeSys videokeratoscope at 3, 10, 20, 30, 40, 50, 65, 75 and 120 weeks postoperatively.

RESULTS: After more than 2 years the axial power- not corrected for the physiologic flattening of the corneas- showed a residual steepening of +3.60 (± 3.90) D for the right eyes and +3.9 (±2.8) D for the left eyes. The diameter of the topographic optical zone was equal to or smaller than the innermost mire. The power started to decrease paracentrally, giving the profile graph of the power a characteristic peak pattern. The flat transition zone, typical of PRK for hyperopia, could be recognized on the Placido images as a characteristic broadening of the midperipheral rings. The axial power map and the power profile did not show this flattening in the transition zone.

CONCLUSION: A steepening of the central cornea by PRK is possible. The diameter of the topographic optical zone of homogeneous power is smaller than induced, increasing considerably the asphericity of the central cornea. The 4-mm/8-mm ablation profiles did not give a larger diameter topographic optical zone nor less regression than the 4-mm/6-mm ablation profiles. The videokeratoscope makes errors in measuring axial power of mixed convex-concave surfaces. [J Refract Surg 1996;12:774-782]
Laser in situ Keratomileusis for Myopia from -5.50 to -11.50 Diopters with Astigmatism
Authors: Zaldivar Roberto , Davidorf Jonathan M , Oscherow Susana
Published: April 2021

ABSTRACT

PURPOSE: To determine the efficacy, predictability, safety, and short-term stability of laser in situ keratomileusis (LASIK) in treating patients with high myopia and astigmatism.

METHODS: We retrospectively studied the results of our initial 119 eyes with myopia ranging from -5.50 to -11.50 D and astigmatism less than 4.00 D that underwent LASIK with the Nidek EC-5000 excimer laser. Follow-up was at 1 day, 1 month, and 3 to 6 months; follow-up was 71% (84 eyes) at the 3 to 6 month visit (average 4.5 months).

RESULTS: Of the 84 eyes with 3 to 6 months of follow-up, mean baseline spherical equivalent refraction was -8.62 ± 1.27 D and mean cylinder was -1.84 ± 1.02 D. Mean postoperative spherical equivalent refraction at the last examination was -0.61 ± 0.84 D and mean cylinder was -0.39 ± 0.38 D, with 83% (70 eyes) achieving a spherical equivalent refraction within ±1.00 D of emmetropia, and 56% (47 eyes) within ±0.50 D. Mean regression of spherical equivalent from 1 day to 1 month was less than -0.50 D and refractions were stable between 1 month and 3 to 6 months. An uncorrected visual acuity of 20/40 or better was noted in 84% (71 eyes) of these eyes on day 1 after surgery, in 75% (63 eyes) at 1 month, and in 77% (65 eyes) at 3 to 6 months. Twenty-two percent (18 eyes) of these eyes achieved 20/20 or better uncorrected visual acuity at 3 to 6 months; only 17% (14 eyes) had 20/20 or better spectacle-corrected visual acuity before surgery. One patient lost two or more lines of spectacle-corrected visual acuity at the last examination due to epidemic keratoconjunctivitis.

CONCLUSION: LASIK with the Nidek EC-5000 excimer laser appears to be an effective and safe means for treating patients with high myopia and astigmatism. Studies with longer follow-up will help evaluate the long-term stability of the procedure and the possibility of late complications. [J Refract Surg 1998;14:19-251
Excimer Laser Photorefractive Keratectomy for Presbyopia: 24-month Follow-up in Three Eyes
Authors: Vinciguerra Paolo , Nizzola Guido Maria , Bailo Giorgio , Nizzola Francesco , Ascari Andrea , Epstein Daniel
Published: April 2021

ABSTRACT

BACKGROUND: For some patients, standard optical correction for presbyopia is not satisfactory. Using a specially designed mask, we developed a procedure for correcting presbyopia with excimer laser photorefractive keratectomy (PRK).

METHODS: A mask consisting of a mobile diaphragm formed by two blunt blades was used to ablate a 10 to 17 µm deep semilunar-shaped zone immediately below the pupillary center, steepening the corneal curvature in that area. Three eyes of three presbyopic patients were treated, aiming at a near addition of +3.00 D. Follow-up time was 24 months.

RESULTS: After an initial regression of 1.00 D during the first 6 months, the presbyopic correction remained stable for the duration of the follow-up period, enabling uncorrected near vision of J3 in all three eyes. Uncorrected distance visual acuity was not altered. Contrast sensitivity (Regan) was slightly decreased only at the 11% level. Videokeratography confirmed corneal steepening in the ablated area.

CONCLUSION: The visual and refractive outcome of excimer laser PRK for presbyopia with the Aesculap-Meditec MEL 60 is promising, especially in view of the 2-year follow-up. [J Refract Surg 1998;14:31-37]
Effect of Decreasing Surface and Interface Irregularities after Photorefractive Keratectomy and Laser in situ Keratomileusis on Optical and Functional Outcomes
Authors: Vinciguerra Paolo , Azzolini Marco , Airaghi Pietro , Radice Paola , De Molfetta Vito
Published: April 2021

ABSTRACT

PURPOSE: To assess a new method for decreasing corneal ablated surface irregularities after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) by performing a final smoothing immediately after the treatment.

METHODS: One hundred forty-seven eyes with ablation irregularities after PRK or LASIK using the Nidek EC-5000 excimer laser and examined with the Nidek EAS 1000, were randomized into two groups: 74 eyes had final smoothing and 73 eyes were patched immediately. Preoperative mean refraction for the smoothing group was -7.55 ± 250 D and for the patched group, it was -7.30 ± 1.90 D, (p = 0.04).

RESULTS: At 12 months after treatment, mean haze was 0.5 ± 0.3 in the smoothing group and 1.2 ± 0.4 in the patched group (p = 0.006); mean spectaclecorrected visual acuity was 1.1 ± 0.25 in the smoothing group and 0.95 ± 0.18 in the patched group (p = 0.02); the percentages of eyes within 1.00 D of the planned correction was 68% in the smoothing group and 33% in the patched group.

CONCLUSION: Performing a final smoothing immediately after PRK or LASIK improves refractive and optical outcomes. [J Refract Surg 1998;14:S199-S203]
Multizone and Transition Zone Photorefractive Keratectomy for High Myopia
Authors: Zhao Kanxing , Wang Yan , Zuo Tong , Wang Hongyue
Published: April 2021

ABSTRACT

BACKGROUND: Variations in ablation profile may alter the stability of refraction and cause adverse effects in photorefractive keratectomy. We compared the benefits of multizone and transition zone ablation in the treatment of high and extreme myopia.

METHODS: A scanning excimer laser system, Nidek EC-5000 was used with three-zone treatment and our results were compared retrospectively with results obtained in a group with a conventional ablation profile using a transition zone.

RESULTS: Six-month follow-up data were available for 65 eyes with a transition zone and 46 eyes with three-zone treatment. Postoperative mean (±SD) healing time was 2.98 days (±0.12) and 3.02 days (±0.15), and night vision disturbances were 16% and 11.5% respectively, (p>0.05). Refractive regression was also similar in the two groups; uncorrected visual acuity of 20/40 or better was 90.77% and 89.14%. At 6 months postoperatively, the mean (±SD) corneal clarity score was 0.61 (±0.29) in the transition zone group, and 0.51 (±0.07) in the multizone group (p<0.05).

CONCLUSION: No discernible differences between treatments were found in either epithelial healing or refractive outcome, such as regression, between the groups. Corneal haze was less in eyes treated with three-zone ablation. [J Refract Surg 1998;14:S222-S225]
Photorefractive Keratectomy for Myopia with -8.00 Diopter Cylindrical Correction
Authors: Shah Sunil , Chatterjee Anupam
Published: April 2021

ABSTRACT

PURPOSE: A colleague requested PRK. The last time the patient was seen, no spectacles or contact lenses were worn. However, subjective refraction was -7.00 -5.50 x 165°. The original Nidek nomogram would have suggested setting the laser at the actual refraction. Our algorithm adjustments suggested a 40% extra correction of cylinder would be required. The laser was therefore set to -3.50 -8.00 ? 165° aiming for a -1.00 -2.00 x 165° outcome to allow for possible retreatment.

METHODS: A 165 µm depth ablation was performed.

RESULTS AND CONCLUSION: At 6 weeks after surgery, visual acuity was 0.63 unaided with a refraction of +1.50 -1.75 x 170° on pred forte. [J Refract Surg 1998;14:S228-S229]
Posterior Chamber Phakic Intraocular Lens for Myopia of -8 to -19 Diopters
Authors: Zaldivar Roberto , Davidorf Jonathan M , Oscherow Susana
Published: April 2021

ABSTRACT

PURPOSE: To examine the efficacy, predictability, stability, and safety of posterior chamber phakic intraocular lens (IOL) implantation in patients with extreme myopia.

METHODS: We analyzed the results of 124 eyes that received a posterior chamber hydrogel collagen plate phakic IOL (Staar Collamer Implantable Contact Lens, ICL) for the correction of their myopia. The target postoperative spherical equivalent refraction was emmetropia. Mean follow-up was 11 months (range 1 to 36 mo).

RESULTS: The mean preoperative spherical equivalent refraction was -13.38 ± 2.23 D (range, -8.50 to -18.63 D). Mean postoperative spherical equivalent refraction at last examination was -0.78 ± 0.87 D (range, +1.63 to -3.50 D), with 69% (86 eyes) within ±1.00 D and 44% (55 eyes) within ±0.50 D of emmetropia. The refraction remained stable with a statistically insignificant change (p > 0.05 at each interval) during follow-up. A gain of two or more lines of spectacle-corrected visual acuity was seen in 36% (45 eyes) at last examination. One eye (0.8%) lost two or more lines of spectacle-corrected visual acuity from a retinal detachment.

CONCLUSION: Posterior chamber phakic IOL implantation with the Staar Collamer plate lens is an effective and safe method for reducing or correcting myopia between -8 and -19 D. Gains in spectacle-corrected visual acuity were common, and results suggested good refractive stability. Improvements in phakic IOL power calculation formulas are needed to improve the predictability of refractive outcome. [J Refract Surg 1998;14:294-305]
Results of Photorefractive Keratectomy for Low, Moderate, and High Myopia
Authors: Tuunanen Tiina H , Tervo Timo T
Published: April 2021

ABSTRACT

PURPOSE: To compare the predictability, safety, and stability of photorefractive keratectomy (PRK) in patient groups with low, moderate, and high myopia. The astigmatic component of these corrections was also evaluated.

METHODS: In 110 patients, 110 consecutive eyes were operated with a VISX 20/20 excimer laser using standard settings and a 6 mm ablation zone for PRK. The eyes were divided into three groups. In low myopia group (N=52) the intended correction ranged from -1.50 to -6.00 D (mean -4.28 ± 1.29 D), in the moderate myopia group (N=34) from -6.10 to -8.00 D (mean -7.05 ± 0.70 D), and in the high myopia group (N=24) from -8.10 to -11.50 D (mean -9.40 ± 1.13 D). Twenty-seven eyes had 0.75 D of preoperative myopic astigmatism. All patients were followed for 12 months and 36% (N=40) were available for the 24-month follow-up examination.

RESULTS: At 12 months the spherical equivalent manifest refraction was within 0.50 D of intended refraction in 58% (N=30) of eyes in the low myopia group, 50% (N= 17) in the moderate myopia group, and 29% (N=7) in the high myopia group. Eighty-seven percent (N=45) in low, 79% (N= 27) in moderate, and 67% (N=16) in the high myopia group were within 1.00 D of intended refraction. At 12 months, 88% (N=46) of the eyes with low myopia, 68% (N=23) with moderate myopia, and 68% (N=16) with high myopia achieved uncorrected visual acuity of 20/40 or better, while 6% (N=16) of the eyes lost and 4% (N=4) gained two or more lines of Snellen visual acuity. Uncorrected visual acuity of 20/20 or better at 12 months was achieved by 58% (N=30) of low myopes, 26% (N=9) of moderate myopes, and 33% (N=8) of high myopes; 20/25 or better by 71% (N=37) of low myopes, 39% (N=13) of moderate myopes, and 42% (N=IO) of high myopes. Overcorrection (>0.25 D) was detected at 12 months in 31% (N=16) with low, 38% (N=13) with moderate, and 67% (N=16) with high baseline myopia, with statistically significant differences between the low and high myopia groups.

CONCLUSION: In all groups, the safety of PRK was satisfactory, without major complications; in the high myopia group where corrections exceeded 8.0 D (mean -9.40 ± 1.13 D) the procedure was only slightly more unpredictable than in low and moderate myopia at 1 year. [J Refract Surg 1998;14:437-446J