bluuebunny/crossref_metadata_2025 huggingface dataset:
Circular and Interrupted Suture Technique for Correction of Hyperopia Following Radial Keratotomy
Authors: Lyle W Andrew , Jin Jia-Chi
Published: April 2021

ABSTRACT

Background: Hyperopia is a possible complication following radial keratotomy. In this article, we describe a circular and interrupted corneal compression suture technique for the correction of hyperopia induced by radial keratotomy.

Methods: A retrospective study was performed to evaluate the effectiveness of this procedure in nine consecutive patients.

Results: The procedure achieved an average of -1.70 diopters change in spherical equivalent refraction. This accounted for an overall correction of 68% of the hyperopia caused by radial keratotomy after a minimum 3-month follow up. Seven of nine eyes (78%) were within 1.00 D of emmetropia after surgery. Uncorrected visual acuity of 20/40 or better was present in only two eyes (22%) preoperatively, and nine eyes (100%), after the corneal suturing procedure. The mean improvement of uncorrected visual acuity was 4.0 Snellen lines (P = .0004). All patients were pleased with their visual outcomes.

Conclusions: We found that this technique is an easy, safe, and reasonably successful treatment for radial keratotomy overcorrection. (Refract Corneal Surg 1992;8:80-83.)
Delayed Sterile Keratitis Following Radial Keratotomy Successfully Treated With Conjunctival Flap
Authors: Mackman Gary
Published: April 2021

ABSTRACT

Background: A case of sterile keratitis involving three adjacent incisions and intervening stroma occurring 5 years after an eight-incision radial keratotomy is reported.

Methods: Multiple cultures showed no pathogens. Treatment with antibiotics, lubricants, patching, and bandage contact lenses failed to improve the condition. A conjunctival bridge flap was therefore performed.

Results: Total resolution of the keratitis occurred rapidly after performing the conjunctival bridge flap.

Conclusions: Delayed keratitis following radial keratotomy has been reported in the past. Treatment in these cases has primarily been corneal transplantation. The present case presents an alternative treatment, conjunctival bridge flap, which was successful in this case of sterile keratitis following radial keratotomy. (Refract Corneal Surg 1992;8:122-124.)
Photorefractive Keratectomy Advances Further in FDA Trials
Authors: Moretti Michael
Published: April 2021

REFRACTIVE LASER UPDATE
Patient Preference-Contact Lens or Radial Keratotomy?
Authors: Haverbeke Luc
Published: April 2021

ABSTRACT

BACKGROUND: Past clinical experience has suggested that patients are more satisfied after radial keratotomy than when wearing contact lenses.

METHODS: One- hundred patients who had worn contact lenses prior to receiving radial keratotomy compared subjectively these two methods for correcting myopia. The postoperative follow up ranged from 3 months to 13 years.

RESULTS: The vast majority (93%) preferred radial keratotomy to the handling of contact lenses.

CONCLUSIONS: The desire to be independent of optical correction is a sufficient indication for refractive surgery. [Refract Corneal Surg 1992;8:315-318.)
Clinical Strategies for Excimer Laser Therapeutic Keratectomy
Authors: Talamo Jonathan H , Steinert Roger F , Puliafito Carmen A
Published: April 2021

ABSTRACT

BACKGROUND: Surgical therapy for superficial corneal scars, dystrophies, or surface irregularities with the 193 nm excimer laser shows great promise. Depending upon the character of the pathology to be treated, different surgical strategies are required.

METHODS: Treatment strategies for three patients with diverse corneal pathology are presented. Focal surface irregularities are treated with small laser spot sizes leaving the epithelium intact. Smooth, uniformly distributed subepithelial anterior stromal pathology is best removed with a large spot size through intact epithelium. When scattered scarring of variable thickness is present, selective epithelial debridement permits improved exposure of irregularities in Bowman's layer and the anterior stroma.

RESULTS: Guidelines for selective debridement of epithelium and protection of adjacent and underlying stroma with moderate viscosity solutions enhances the surgeons's ability to obtain a smooth and clear surface while minimizing corneal thinning. Even with these strategies and use of piano disc ablation, net hyperopic shift generally occurs with broad large area therapeutic ablation.

CONCLUSIONS: Superficial corneal opacities and irregularities can be surgically treated with the excimer laser as an alternative to the more invasive procedure of lamellar keratoplasty. Treatment failures can then go on to lamellar keratoplasty while successfully treated patients are more rapidly rehabilitated at lower total cost than a lamellar graft. Refinement of treatment strategies to minimize the hyperopic shift and facilitate masking around irregularities will further improve the results. Refract Corneal Surg 1992;8:319-324.)
Modified Surgical Technique for Repeated Epikeratophakia Surgery in Aphakic Eyes
Authors: Busin Massimo , Cusumano Andrea
Published: April 2021

ABSTRACT

BACKGROUND: Incomplete epithelial removal from the peripheral keratectomy at the time of repeat epikeratophakia surgery can lead to interface downgrowth and consequent failure, as observed in the case reported herein. We present a modification of the standard surgical technique aimed at avoiding such complication.

METHODS: A 69-year-old white female underwent a third aphakic epikeratophakia modified to reduce the risk of epithelial interface downgrowth, which had caused a previous failure. The aphakic tissue lens, 8.5 mm in diameter, was sutured into a corneal pocket obtained at a deeper level, inside the peripheral keratectomy used for the previous two procedures.

RESULTS: Useful visual acuity (20/60) was obtained and the refractive outcome remained stable up to 1 year postoperatively. Epithelial interface downgrowth did not recur.

CONCLUSIONS: Despite the possible risk of perforation while undermining the recipient cornea at a deeper level, the modified technique might offer a more effective method of preventing epithelial downgrowth after repeat epikeratophakia surgery. [Refract Corneal Surg 1992;8:382384).
Combined Epikeratoplasty and Homoplastic Keratophakia for Correction of Aphakia: Double Curve Effect
Authors: Burillon Carole , Durand Luc , Gourraud Anne
Published: April 2021

ABSTRACT

BACKGROUND: Having used the nonfreeze Barraquer-Krumeich-Swinger set for refractive lamellar keratoplasty since January 1987, the authors found the results of this procedure to be disappointing for correction of aphakia. Insufficient refractive gains for epikeratoplasty ( + 39% of initial refraction at 12-month follow up) persuaded the authors to look for a more effective refractive corneal surgery technique for correcting aphakia.

METHODS: We describe a new technique consisting of the insertion of a plano-convex homoplastic donor cornea meniscus between the patient's cornea and a hypermetropic epikeratoplasty. A nonfreeze Barraquer-Krumeich-Swinger set was used to fashion the two donor lenticules. This double surgery, called the "double curve effect," because it uses two convex surfaces to increase the converging power of the cornea, has been performed in 15 eyes.

RESULTS: We report the results of 10 eyes with a 6-month follow up. The average refractive gain was + 11.75 D, 90% of the needed correction. But there was a loss of approximately 46% of best spectacle-corrected visual acuity.

CONCLUSION: Three problems should be emphasized: the existence of two interfaces, the difficulty of perfectly centering the two lenticules, and the inäuced irregulär astigmatism. Despite these problems which can reduce the level of best spectacle-corrected visual acuity, the double curve effect may offer an effective solution for treating certain cases of unilateral aphakia. [Refract Cornea! Surg. 1993;9;2J4-218.)
Design and Development of a New 193-Nanometer Excimer Laser Surgical System
Authors: Förster Werner , Beck Rasmus , Busse Holger
Published: April 2021

ABSTRACT

BACKGROUND: The 193 -nanometer excimer laser is used for photoablative reprofiling of the cornea to correct refraction errors and to treat corneal pathologies. To use the unique properties of the excimer laser, some technical features should be provided by the excimer laser system. A new excimer laser system is presented.

METHODS: The instrument has a fluence sensor for precise measurement of the actual fluence just before surgery, a new delivery system including an integrator system to homogenize the laser beam, a steelband with apertures and a zoom optic to get the desired form of central reprofiling, and an alignment system to reduce the possibility to decenter the optical zone.

RESULTS: The fluence before surgery can be measured very precisely with the fluence sensor. The ablation zone size is at least 8 mm fn diameter with a homogenous laser beam profile resulting in a smooth surface of the treated material. Different forms of ablations can be created using the steelband with different forms of apertures. The center of the ablation zone can be found using the alignment system.

CONCLUSION: The new excimer laser system fulfills some important technical features for optimal use of the excimer laser in corneal surgery. (Refract Corneal Surg 1993;9:293-299.)
Effect of Topical Interferon-Alpha 2b on Corneal Haze After Excimer Laser Photorefractive Keratectomy in Rabbits
Authors: Monet Nigel , Gillies Mark C , Crouch Roger , Maloof Anthony
Published: April 2021

ABSTRACT

BACKGROUND: Anterior corneal stromal keratocytes are activated by excimer laser photorefractive keratectomy resulting in haze with healing of the ablated area. In some eyes, this causes a visible haze or scar on the cornea, and an unpredictable regression of the myopic correction following refractive ablations.

METHODS: Following a 6.00-diopter excimer laser photorefractive keratectomy to both eyes, 16 rabbits were treated for 5 weeks with interferonalpha 2b drops four times a day to one eye only. Eight of these rabbits were treated with dexamethasone drops four times a day to both eyes. Using a standard grading scale for haze, the corneas were examined and the haze graded weekly.

RESULTS: The observed corneal haze was significantly reduced in the treated eyes by the application of topical interferon-alpha 2b drops (P=. 004), and topical dexamethasone drops (?<.00?). Topical dexamethasone also produced less haze in combination with interferon-alpha 2b than when used alone (p= .035). There was continuing resolution of the corneal haze in those rabbits observed for 7 weeks after the cessation of the drops. Topical interferon-alpha therapy was not toxic to the rabbit eye and was not associated with delayed reepithelialization after the laser procedure.

CONCLUSION: Topical interferon-alpha 2b appears to reduce the corneal haze produced by excimer laser photorefractive keratectomy in rabbits. Refract Corneal Surg. 1993;9:443-451.)

RÉSUMÉ

INTRODUCTION: Les kératocytes dans Ie stroma antérieur sont activés par la kératectomie photorefractive au laser excimer, ce qui produit une brume légère pendant la cicatrisation. Cette brume légère entraine une cicatrice visible et un effet/éfractif non-prévisible en certain cas.

MÉTHODES: Seize lapins furent traités 4 fois par jour pendant 5 semaines avec les gouttes d'interferon-alpha 2b sur un oeil uniquement, suivant une kératectomie photo-réfractive de 6 dioptries sur les deux yeux. Huit de ces lapins furent traités avec les gouttes de dexamethasone 4 fois par jour sur les deux yeux. Les cornées furent examinées et la brume légère fut classifiée une fois par semaine, utilisant une échelle standardisée.

RÉSULTATS: Nous avons observé significativement moins de brume chez les yeux traités par !'interferon -alpha 2b (p= 0,004), et ceux traités par les gouttes de dexamethasone (0,001). La dexamethasone a produit moins de brume légère combinée avec G interferon -alpha 2b qu'en usage seule (p =0,035). La brume légère disparait progressivement pendant les 7 semaines après l'arrêt des gouttes. L'utilisation de l'interferon-alpha 2b n'a pas montré d'effet toxique sur l'oeil du lapin et n'a pas entraîné de délai dans i'epithélialisation en postopératoire.
Automated Lamellar Keratomileusis In Situ for Myopia
Authors: Price Francis W , Whitson William E , Gonzales Jill S , Gonzales Celedon R , Smith Jocelyn
Published: April 2021

ABSTRACT

BACKGROUND: Keratomileusis in situ, particularly automated lamellar keratoplasty, is a commonly performed technique of keratomileusis in the United States.

METHODS: A single center consecutive series of 152 eyes undergoing keratomileusis in situ for myopia was analyzed. Spherical equivalent refractions were compared before and after surgery. The standard nomogram supplied with the automatic corneal shaper (Chiron Vision Corp, Irvine, Calif) was used. The mean of preoperative myopia treated was -9.30 ± 3.10 diopters (D) (range, -5.12 to -22.75 D).

RESULTS: Of the 144 eyes with 1 month follow up, 30 (21%) were within 0.50 D of the planned correction at 1 month, 54 (38%) were within 1.00 D, and 97 (67%) were within 2.00 D. At 6 or more months follow up, 51 of 68 eyes (75%) achieved uncorrected visual acuity of 20/40 or better and 13 of 68 (19%) 20/20 or better when eyes with macular degeneration and amblyopia were removed. Forty-six of 78 eyes (59%) with 6 months or greater follow up required retreatment procedures to correct residual myopia or astigmatism. Multiple regression analysis explained 40% of the variation between attempted correction and postoperative results. An overall 5% shift of refraction in the myopic direction occurred between 1 and 6 months. Of the 110 eyes with both 1- and 3-month examinations, the spherical equivalent refraction changed between these time intervals by 1.00 D or more in 54 (49%) eyes; and 11 (31%) eyes changed by 1.00 D or more between the 3- and 6-month examinations. Although 6% of eyes lost 2 or more lines of spectacle-corrected visual acuity, 11% gained 2 or more lines.

CONCLUSION: Myopic keratomileusis in situ using the automated lamellar keratoplasty technique appears to be a safe and most effective procedure to reduce moderate to high myopia. However, the predictability of the procedure needs improvement. [J Refract Surg. 1996;12:29-35.]
Radial Keratotomy for Myopia From 5.00 to 13.00 Diopters Two Years After Surgery
Authors: Percival S Piers B , Vyas Ashok V
Published: April 2021

ABSTRACT

BACKGROUND: Radial keratotomy for low myopia can produce good results with few side effects. For higher myopia, predictability becomes less accurate and side effects more common.

METHODS: A retrospective study of 111 eyes of 76 patients were divided into two groups. Group I had 79 eyes with myopia of -5.00 to -8.00 diopters (D); group II had 32 eyes with myopia -8.25 D to -13.00 D. One hundred eleven eyes were followed for 1 year and 90 eyes were followed for 2 years.

RESULTS: Sixty-seven (84.8%) eyes in group I and 12 (37.5%) eyes in group II achieved a refraction within the range of -1.00 D and +1.00 D. Ninety-two percent of group I and 44% of group II achieved an uncorrected visual acuity of 20/40 or better. Three percent lost spectacle-corrected visual acuity. Four eyes developed a hyperopic shift of 1.00 D or more between 2 months and 2 years. Seven other eyes developed a hyperopic shift of 1.00 D or more between 2 months and 5 years.

CONCLUSIONS: Eight-incision radial keratotomy is an attractive option for treatment of myopia up to -8.00 D. For levels above -8.00 D, the results are poorer; there may be a variable period before refraction stabilizes. [J Refract Surg. 1996;12:86-90.]
Multicomponent Intraocular Lens
Authors: Werblin Theodore P
Published: April 2021

ABSTRACT

BACKGROUND: Refractive surgery for any form of ametropia, including postoperative cataract rehabilitation, should have as its refractive goal an accuracy comparable to non-surgical modalities such as contact lenses and spectacles. To date, all refractive procedures fall significantly short of this goal because of poor predictability, significant instability, and annoying optical side effects. The multicomponent intraocular lens is being developed to further refine the accuracy of conventional IOL surgery by making the initial refractive result adjustable.

METHODS: The multicomponent intraocular lens has three optical elements. The spherical base lens looks much like an ordinary PC-IOL. Attached to it are two exchangeable optical elements-a toric sandwich lens and a spherical or multifocal cap lens. The exchangeable elements allow the surgeon to refine the initial refractive result during a second, optional operative procedure.

RESULTS: To date, prototype lenses have been fabricated from polymethylmethacrylate. These lenses have been assembled and disassembled both in vitro and in cat eyes to demonstrate the feasibility of this new concept.

CONCLUSION: The multicomponent intraocular lens concept is a major departure from conventional IOL technology because it allows enhancement, or fine tuning, of an already fairly accurate refractive procedure, IOL surgery. [J Refract Surg. 1996;12:187-189.]
Successful Phototherapeutic Keratectomy for Recurrent Erosions in Bullous Keratopathy
Authors: Thomann Urs , Niesen Ulrike , Schipper lsaak
Published: April 2021

ABSTRACT

BACKGROUND: The treatment of patients with recurrent erosions due to bullous keratopathy is disappointing in cases when penetrating keratoplasty cannot be performed. A trial has been made to prevent recurrent erosions through the smoothing of the cornea with the excimer laser.

METHODS: Excimer laser phototherapeutic keratectomy (PTK) was performed after removal of the epithelium.

RESULTS: Sixteen patients (17 eyes) with recurrent erosions due to bullous keratopathy were treated. The mean follow-up period was 17.2 months (range: 3 to 32 months). All patients responded well to the treatment; their pain subsided after a few weeks. In four cases, a second treatment was necessary because areas with loose epithelium remained, which resulted in recurrent erosions. No complications have been seen so far.

CONCLUSION: Excimer laser PTK is an effective, easy to perform treatment of bullous keratopathy. [J Refract Surg. 1996;12:S290-S292.]
Incision Depth vs. Incision Number in the Rupture Strength of Pig Eyes Following Radial Keratotomy
Authors: Kung John S , Lucca John A , Santaniaria Jaime
Published: April 2021

Radial Keratotomy
Corneal Topography, Arcuate Keratotomy, and Compression Sutures for Astigmatism After Penetrating Keratoplasty
Authors: Koffler Bruce H , Smith Vivien M
Published: April 2021

ABSTRACT

BACKGROUND: Twenty (20) patients with postpenetrating keratoplasty (PKP) (21 eyes) and excessive corneal astigmatism were studied using corneal topography to determine placement of arcuate incisions and compression sutures for astigmatism reduction.

METHODS: Keratoplasty wounds and compression sutures were placed asymmetrically based on corneal topography only. Incisions were at the donor-host junction at a depth of 500 microns.

RESULTS: A 56% reduction in corneal astigmatism was accomplished with an average cylinder reduction of 5.3 D. Keratometry readings were reduced in 18 of 20 (90%) of eyes and refractive cylinder was reduced in 15 of 20 (75%) of eyes. Corrected visual acuity improved in 15 of 20 (75%) declined in 15%, and did not change in 10%.

CONCLUSION: Visual acuity can be improved by manipulating the astigmatism after penetrating keratoplasty using corneal topography maps to determine placement of arcuate incisions and compression sutures. [J Refract Surg. 1996;12:S306-S309.]
Acute Tissue Deformation of the Human Cornea After Radial Keratotomy
Authors: Hjortdal Jesper Ø , Ehlers Niels
Published: April 2021

ABSTRACT

PURPOSE: The regional deformation pattern of the cornea after radial keratotomy, which is essential for understanding the mode of action of the procedure, has not previously been studied in detail.

METHODS: Up to 90 tiny mercury droplets were placed from center to limbus on the epithelial and endothelial corneal surfaces of eight eviscerated human donor eyes with four radial keratotomies (depth 100% of central corneal thickness, 3.5-mm clear zone). From digital images obtained under pressure loads ranging from 2 to 100 mm Hg, the distances between the fixed droplets were measured with an accuracy of 1 µ??. After transforming the data to polar coordinates, regional meridional and circumferential strain patterns were calculated. Regional meridional and circumferential radii of curvatures were calculated from corneal profile images obtained at different pressure loads before and after keratotomy.

RESULTS: Increasing the intraocular pressure from 2 to 100 mm Hg induced: an epithelial side wound gape of 44 mm; epithelial side circumferential tissue compression between incisions; considerable epithelial side meridional tissue elongation at and between incisions; little endothelial side circumferential strain across incisions; and little endothelial side meridional strain at and between incisions.

The radial keratotomy induced 2.30 diopters (D) of central corneal flattening at an intraocular pressure of 2 mm Hg. The degree of central flattening correlated linearly with the amount of wound gape. In the physiological pressure range of the central cornea flattened 0.05 D for each millimeter-of-mercury increment in intraocular pressure. Pronounced meridional steepening was induced corresponding to the middle and peripheral parts of the keratotomy incisions.

CONCLUSIONS: Our study suggests that the peripheral "tissue addition" seen after radial keratotomy is a net result of wound gape and circumferential tissue compression. Local bending of intact stromal tissue below the incisions plays an important role for the generation of the wound gape at the corneal surface. These data may help verify finite-element computer models of the human cornea. [J Refract Surg. 1996;12:391-400.]
Photorefractive Keratectomy for Compound Myopic Astigmatism With an Eye Cup Erodible Mask Delivery System
Authors: Brancato Rosario , Carones Francesco , Venturi Elisabetta , Morico Alessandro , Gobbi Pier Giorgio
Published: April 2021

ABSTRACT

BACKGROUND: The erodible mask is a new energy delivery system for the 193-nm argon fluoride excimer laser. It consists of a polymethylmethacrylate button, whose profile is transferred by photoablation onto the corneal surface. We present the 6- and 12-month results of this technique in the correction of compound myopic astigmatism.

METHODS: We performed the mask procedure on 21 eyes of 16 subjects (mean age, 30.7 years; range, 24 to 46) to correct combined myopia and astigmatism. Attempted myopic correction ranged between -1.50 diopters (D) and -10.00 D (mean, -7.07 D). Attempted astigmatic correction ranged between -1.50 D and -4.00 D (mean, -2.46 D).

RESULTS: Mean procedure error was: sphere +0.74 D (range, -3.00/+5.00), cylinder -1.41 D (range, -3.50/0.00) at 1 month after surgery; sphere +0.18 D (range, -2.50/+3.50), cylinder -1.56 D (range, -4.00/0.00) at 6 months; and sphere -1.30 D (range, -3.00/0.00), cylinder was -1.25 D (range, -2.00/-0.50) at 12 months (10 eyes). During follow up, haze values were never higher than 1, except for one case of haze 2 that regressed to 0 during follow up. Postoperative uncorrected visual acuity improved in all eyes where emmetropia was envisaged; none of the eyes lost spectacle-corrected visual acuity lines 6 or 12 months after surgery.

CONCLUSIONS: The erodible mask proved effective and fairly predictable mainly in the correction of the spherical component of refractive error, while the correction of astigmatism revealed greater unpredictability, with a constant trend to undercorrection. [J Refract Surg. 1996;12:501-511.]
Autologous Keratophakia for the Correction of Consecutive Hyperopia After Automated Lamellar Keratoplasty for Myopia
Authors: Chan Wing-Kwong , Maloney Robert K
Published: April 2021

ABSTRACT

PURPOSE: Consecutive hyperopia occurs if too much corneal tissue is resected during automated lamellar keratoplasty for myopia. We report what are, to our knowledge, the first two cases of consecutive hyperopia after automated lamellar keratoplasty that were treated by keratophakia with autologous corneal tissue.

METHODS: The patient in case 1 had a spherical equivalent refraction of +3.38 diopters (D) and the patient in case 2 a refraction of +3.63 D in each eye after automated lamellar keratoplasty for myopia. Corneal tissue from the contralateral eye of each patient was obtained with an automated microkeratome and transferred to the overcorrected eye in an autologous keratophakia procedure.

RESULTS: The patient in case 1 had an unaided visual acuity of 20/20, with a spherical equivalent refraction of +0.63 D 4 months after the autologous keratophakia. The patient in case 2 had an unaided visual acuity of 20/60, with a spherical equivalent refraction of -2.25 D 2.5 months postoperatively.

CONCLUSION: These two cases illustrate the use of simultaneous contralateral myopic automated lamellar keratoplasty with autologous keratophakia to treat eyes overcorrected following previous automated lamellar keratoplasty for myopia. [J Refract Surg. 1996;12:514-516.]
Epithelial Inclusion Cysts Following Epikeratoplasty
Authors: Al-Rajhi Ali A , Al-Kharashi Soliman A
Published: April 2021

ABSTRACT

BACKGROUND: Epikeratoplasty for keratoglobus performed to tectonically support the thin globular cornea may have complications such as interface opacities.

METHODS: We report the case of a patient with persistent interface opacities and epithelial cysts following epikeratoplasty for keratoglobus that were treated primarily by washouts and repeated argon laser photocoagulation.

RESULTS: Interface opacities led to massive epithelial inclusion cysts. Direct removal of these cysts and placement of a new lamellar graft resulted in a favorable outcome.

CONCLUSION: Massive epithelial inclusion cysts may develop in the lamellar interface after epikeratoplasty. Direct surgical removal was successful. [J Refract Surg. 1996;12:517-520.]
Ultrastructure of Picosecond Laser Intrastromal Photodisruption
Authors: Krueger Ronald R , Quantock Andrew J , Juhasz Tibor , Ito Mitsutoshi , Assil Kerry K , Schanzlin David J
Published: April 2021

ABSTRACT

PURPOSE: To investigate the ultrastructure of the corneal stroma after picosecond intrastromal photodisruption with a neodymium-doped yttriumlithium-fluoride (Nd:YLF) laser.

METHODS: We performed picosecond intrastromal photodisruption on six human eye-bank eyes using a lamellar technique. Thirty picosecond pulses at 1000 Hz and 20 to 25 mj per pulse were placed in an expanding spiral pattern, the pulses separated by 15 um. Three layers were placed in the anterior stroma, separated from each other by 15 uni. In addition, intrastromal radial and arcuate incisions were generated in two living rabbit eyes in a plane perpendicular to the corneal surface. After the procedure, the corneas were processed for scanning and transmission electron microscopy.

RESULTS: Scanning electron microscopy of the eye-bank eyes demonstrated multiple, coalescing intrastromal cavities forming a layer oriented parallel to the corneal surface. These cavities had smooth inner walls. Transmission electron microscopy demonstrated tissue loss surrounding some cavities, with the terminated ends of collagen fibrils clearly evident. Other cavities were formed by separation of lamellae, with little evidence of tissue loss. A pseudomembrane was present along the margin of some cavities. Although there was occasional underlying tissue disruption along the border of a cavity, there was no evidence of thermal damage or tissue necrosis. The perpendicular photodisruptions demonstrated intrastromal cleavage of corneal collagen similar to diamond-knife incisions, with the exception of intact overlying Bowman's and epithelial layers.

CONCLUSION: Intrastromal photodisruption with a Nd:YLF picosecond laser induced no thermal necrosis or coagulative change in the region of tiesue interaction. Lamellar intrastromal photodisruption demonstrated both tissue loss and lamellar separation when performed with the current treatment parameters, possibly limiting ablation efficiency and predictability. [J Refract Surg. 1996;12:607-612.]
Corneal Wound Healing and Nerve Morphology after Excimer Laser In Situ Keratomileusis in Human Eyes
Authors: Latvala Terho , Barraquer-Coll Carmen , Tervo Kaarina , Tervo Timo
Published: April 2021

ABSTRACT

BACKGROUND; Our aim was to describe wound healing and nerve regeneration in the human cornea after excimer laser in situ keratomileusis.

METHODS: Excimer laser in situ keratomileusis was done in three human eyes 8 days, 54 days, and 4 months prior to enucleation. Acetylcholinesterase reaction was used to histochemically demonstrate the corneal nerves. Immunohistochemical methods were used to demonstrate the following wound healing proteins: cellular fibronectin, tenascin, transforming growth factor-ßl, and a-smooth muscle actin.

RESULTS: All corneas healed without complication. No epithelial hyperplasia appeared and the Bowman's layer was smooth and acellular. An epithelial plug extending up to 100-300 µ?? under the flap margins was seen in all specimens. Regenerative nerve fiber bundles emerging from sharply cut anterior stromal nerves were observed, but the deeper nerves were normal. Restricted expression of fibronectin and tenascin was found at the wound area. All corneal cell types were positive for transforming growth factor-ßl antibody. Cells lining the limbal vessels were positive for a-smooth muscle actin antibody whereas the corneal cells were negative.

CONCLUSIONS: The nerve morphology showed only a few abnormalities, especially in deep stromal nerves. Epithelial plugs at the flap margins may maintain a delayed wound healing process for several months but otherwise the process remained active for a relatively short time. [J Refract Surg 1996;12:677-683]
Histopathological Comparison of Photorefractive Keratectomy and Laser In Situ Keratomileusis in Rabbits
Authors: Amm Marita , Wetzel Wolfgang , Winter Martin , Uthoff Detler , Duncker Gernot I W
Published: April 2021

ABSTRACT

BACKGROUND: After 193 nm excimer laser photorefractive keratectomy (PRK) for myopia, superficial opacities in the ablation zone and regression of refractive results can occur. Clinical studies have emphasized that corneal clarity and early refractive stability can be achieved with laser in situ keratomileusis (LASDX). We present clinical and histological results that compare PRK and LASIK for the treatment of myopia in rabbits.

MATERIALS AND METHODS: We treated 12 New Zealand white rabbits with PRK and 12 with LASLK using a 193-nm excimer laser (Aesculap Meditec). In both techniques, the identical excimer software and ablation parameters of -10 D treatment depth were used. Six months after surgery, all eyes were removed and prepared for light, fluorescence and transmission electron microscopy.

RESULTS: At the time of enucleation, nine eyes in the PRK group had a moderate to high degree of haze (grade 2 to 3), whereas after LASIK, all corneas showed an almost clear interface in the ablation zone. Correspondingly, all histological investigations after LASIK showed a regular stromal architecture, in contrast to the obvious anterior stromal disorganization after PRK.

CONCLUSION: The preserved integrity of the superficial corneal layers after LASLK ensures quick wound healing with minimal tissue proliferation, resulting in a transparent corneal interface. This technique appears especially suitable for correcting high myopia. [J Refract Surg 1996;12:758-766]
Photorefractive Keratectomy after Radial Keratotomy
Authors: Al-Rajhi Ali A , Risco J Miguel , Badr Ihsan A , Teichmann Klaus D
Published: April 2021

ABSTRACT

BACKGROUND: Twenty-three eyes of 22 patients remained undercorrected 5 to 49 months after radial keratotomy, either alone or in combination with transverse keratotomy.

METHOD: We attempted to correct the residual myopia ranging from -1.25 to -5.75 diopters (D) (with astigmatism of 0 to 1.25 D) with photorefractive keratectomy. The mean age of patients was 26 years (range 22 to 40 years).

RESULTS: After photorefractive keratectomy (follow-up 6 to 17 months) uncorrected visual acuity was equal to or better than 20/20 in 39% (9 eyes), better than 20/25 in 65% (15 eyes), and better than 20/40 in 74% (17 eyes). Spectacle-corrected visual acuity was equal or better than 20/40 in all eyes; one eye (4%) lost two lines of spectacle-corrected visual acuity. Refractive error was within ±0.50 D in 48% (11 eyes) and within ±1.00 D in 65% (15 eyes). Undercorrections of more than 1.00 D occurred in 22% (5 eyes) and overcorrections of more than 1.00 D occurred in 13% (3 eyes). No or minimal haze was present in 57% (13 eyes), mild haze in 39% (9 eyes) and moderate haze in 4% (1 eye). Final uncorrected visual acuity was better (p=0.0002) and haze was less (p=0.003) in the group with less than -3.00 D than in the group with greater than or equal to -3.00 D.

CONCLUSION: Photorefractive keratectomy after radial keratotomy is safe but less effective and less predictable in eyes with greater than or equal to -3.00 D compared to those with less than -3.00 D. [J Refract Surg 1996;12:801-805]
Intraocular Lens Power Calculation for Cataract Surgery after Photorefractive Keratectomy for High Myopia
Authors: Kalski Richard S , Danjoux Jean-Pierre , Fraenkel Graham E , Lawless Michael A , Rogers Christopher
Published: April 2021

ABSTRACT

OBJECTIVE: To assess intraocular lens (IOL) power calculations in patients undergoing cataract surgery after excimer laser photorefractive keratectomy (PRK) for myopia.

METHODS: Four eyes of two patients underwent phacoemulsification with IOL implantation after PRK for myopia. The estimated refractive error that would have been induced had the IOL predicted for emmetropia been implanted was calculated using SRK-n, SBKfT, Holladay, and Binkhorst formulas. Manual keratometry and videokeratography-simulated keratometry values measured before surgery were used. Keratometry values calculated by subtracting the refractive change induced by the excimer laser PRK from the manual keratometry or videokeratography-simulated keratometry values measured before PRK were also used. Both spectacle and corneal plane calculations were performed.

RESULTS: Manual keratometry and videokeratography-simulated keratometry values underpredieted the IOL power. Corneal plane manual or videokeratography refraction-derived keratometry calculations were most accurate using the SRKT formula, while spectacle plane calculations were most accurate using the SRK-II formula. In both methods the calculated refractive error was within 0.52 diopters (D) for the emmetropic lens power predicted. Statistical analysis was not performed.

CONCLUSIONS: Refraction-derived keratometric values provided the most accuracy in calculating IOL powers. Our results suggest the SRK/T formula was the most accurate for corneal plane calculations, while the SRK-II formula was the most accurate for spectacle plane calculations. [J Refract Surg 1997;13:362-366]
Assessment of Corneal Wound Healing by Interactive Topography
Authors: Buzard Kurt A , Fundingsland Bradley R
Published: April 2021

ABSTRACT

INTRODUCTION: Constitutive properties of the cornea and wounds within the cornea have been measured previously by destructive methods in which a strip of cornea was removed, placed on an instrument, and stretched until broken. To assess corneal wound healing and the interaction of medication, incision patterns and other clinical issues, we present a simple, noninvasive test of corneal wound healing utilizing a videokeratoscope and Honan 'balloon.

METHODS: A pre-test corneal topography was performed. The Honan balloon was placed on the eye at a pressure of 30mm mercury for 5 minutes. After removal of the balloon, additional corneal topographies were performed for comparison to the baseline topography. Study eyes were divided into six groups: 15 eyes in the normal group not involved in the Honan balloon test, 15 eyes formed a control group without previous ocular surgery, 15 eyes were within 3 months of radial keratotomy (RK), 15 eyes were more than 9 months after RK, 12 eyes had previous automated in situ keratomileusis (ALK), and 12 eyes had previous penetrating keratoplasty (PK).

RESULTS: Average videokeratometric flattening was reported for all groups at intervals of 1, 2, and 3 minutes after removal of the Honan balloon. The normal group flattened by 0.04 ± 0. 10 D (range, +0.10 to -0.12 D) at 1 minute; 0.02 ± 0.08 D (range, +0.1 0 to -0.10 D) at 2 minutes; and 0.02 ± 0.06 D (range, +0.10 to -0. 09 D) at 3 minutes. The control group flattened by -0.10 ± 0.10 D (range, +0.30 to -0.30 D) at 1 minute; 0.01 ± 0.12 D (range, +0.15 to -0.25 D) at 2 minutes; and 0.07 ± 0.11 D (range, +0.14 to -0.18 D) at 3 minutes. The 3-month RK group flattened 0.95 ± 0.23 D (range, 1.35 to 0.67 D) at 1 minute; 0.53 ± 0.16 D (range, 0.71 to 0.39 D) at 2 minutes; and 0.40 ± 0.15 D (range, 0.56 to 0.30 D) at 3 minutes. The 9-month RK group flattened 0.10 ± 0.13 D (range, 0.23 to 0.02 D) at 1 minute; 0.10 ± 0. 12 D (range, 0.18 to -0.01 D) at 2 minutes; and 0.01 ± 0.14 D (range 0.05 to 0.10 D) at 3 minutes. The ALK group flattened 0.65 ± 0.42 D (range 0.98 to 0.38 D) at 1 minute; 0.27 ± 0.19 D (range 0.39 to 0.10 D) at 2 minutes; and 0.21 ± 0.17 D (range, 0.29 to 0.09 D) at 3 minutes. The PK group flattened 1.30 ± 0.60 D (range, 1.75 to 0.90 D) at 1 minute; 1.18 ± 0.43 D (range, 1.51 to 0.98 D) at 2 minutes; and 0.41 ± 0.57 D (range, 0.88 to 0.30 D) at 3 minutes.

CONCLUSIONS: We have established normal corneal wound healing curves from preliminary data utilizing Buzard interactive topography on normal control eyes and after radial keratotomy, automated lamellar keratoplasty, and penetrating keratoplasty. Deviation from these normal curves indicates either excessive or inadequate wound healing. [J Refract Surg 1998;14:53-60]
Clear Lensectomy and Intraocular Lens Implantation for Hyperopia from +7 to +14 Diopters
Authors: Siganos Dimitrios S , Pallikaris Ioannis G
Published: April 2021

ABSTRACT

BACKGROUND: Our results of clear lens extraction and intraocular lens implantation to correct hyperopia from +6.75 to +13.75 D are presented, as well as evaluation of two intraocular lens calculation formulae.

METHODS: Clear lens extraction and posterior chamber intraocular lens implantation was performed in 35 normally sighted eyes of 21 patients with a mean baseline hyperopic spherical equivalent refraction of +9.19 ± 0.34 D (range +6.75 to +13.75 D). The refractive goal was -1.50 D, using the SRK II formula in 17 eyes and the SRK-T formula in 18 eyes. Follow-up was up to 5 years.

RESULTS: Mean uncorrected visual acuity after surgery was 0.8 (range 0.5 to 1.0). Stability of refraction was noted from the second month after surgery. No eyes lost any lines of spectacle-corrected visual acuity. Using the SRK II formula, 100% of eyes were within ±1.00 D of emmetropia and with the SRK-T formula, 83.3% for a combined 91.4% of eyes within ±1.00 D of emmetropia. One eye required intraocular lens exchange and another eye required photorefractive keratectomy for myopia. Both procedures were necessitated by an intraocular lens miscalculation of more than ±2.00 D. Nineteen eyes (54.2%) developed posterior capsular opacification and were treated with Nd:YAG laser capsulotomy.

CONCLUSION: Clear lens extraction is a safe, effective, and predictable procedure for the treatment of hyperopia from +6.75 to +13.75 D. The SRK II formula proved slightly superior to the SRK-T in intraocular lens calculation when using the "-1.50 D rule." [J Refract Surg 1998;14:105-113].
Treatment of Corneal Dystrophies with Phototherapeutic Keratectomy
Authors: Örndahl Mats J F , Fagerholm Per P
Published: April 2021

ABSTRACT

PURPOSE: To evaluate the excimer laser as a surgical instrument for treatment of corneal dystrophies.

METHODS: Excimer laser photoablation was performed with the Summit UV 200 and VISX 20/20 excimer lasers on 30 eyes of 21 patients with different types of corneal dystrophies; phototherapeutic keratectomy (PTK) on 28 eyes (20 patients) and photorefractive keratectomy (PRK) on two eyes (one patient). The treatment goals were to improve visual acuity (26 eyes of 18 patients), heal recurrent corneal erosions (eight eyes of five patients), and treat fluctuating refraction and visual acuity (three eyes of two patients). Mean follow-up was 37 months (range 24 to 54 mo). The dystrophy groups included: map-dot-fingerprint (nine eyes of seven patients), lattice type I (five eyes of four patients), lattice type II (two eyes of one patient), granular (five eyes of three patients), central crystalline (four eyes of three patients), ReisBücklers' (two eyes of one patient), Meesmann's (two eyes of one patient), and Fuchs' endothelial (one eye).

RESULTS: In 22 of 26 eyes (84.6%) there was an improvement in spectacle-corrected visual acuity after 6 to 12 months. This improvement remained stable in 18 eyes (69.2%). Pronounced recurrences of dystrophic changes with reduction in visual acuity were seen in three eyes of two patients: lattice type II (two eyes) and granular (one eye). In one eye with Fuchs' endothelial dystrophy, there was a recurrence of subepithelial fibrosis which had been previously removed. In eight of eight eyes (100%) treated for recurrent corneal erosions (map-dot-fingerprint, Meesmann's, and lattice type I), the erosions healed shortly after treatment and did not recur. Preoperative fluctuating refraction stabilized in three of three eyes (100%) with mapdot-fingerprint after treatment. The mean hyperopic refractive shift was +2.55 ± 2.16 D. In none of the patients did the treatment per se lead to a decrease in spectacle-corrected visual acuity or any corneal surface problems.

CONCLUSION: In corneal dystrophies with epithelial and anterior stromal opacities, excimer laser PTK may be successful in improving vision and healing recurrent corneal erosions over the long term. [J Refract Surg 1998;14:129-135]
Retreatment of Regression after Photorefractive Keratectomy for Myopia
Authors: Vorotnikova E K , Kourenkov V V , Polunin G S
Published: April 2021

ABSTRACT

PURPOSE: To study results of retreatment after regression in myopic patients who underwent photorefractive keratectomy (PRK).

METHODS: Procedures were performed with the Nidek EC-5000 excimer laser. This was a retrospective study of 20 of 2127 patients, with follow-up of at least 6 months, who underwent repeated excimer laser ablation.

RESULTS: No patient with low myopia had regression. We evaluated six eyes (group I) with moderate myopia; 13 eyes (group ?) with high myopia; and ten eyes (group III) with extreme myopia. Average uncorrected visual acuity at 6 months after retreatment was 0.73 ± 0.21 in group I, 0.64 ± 0.35 in group II, and 0.61 ± 0.38 in group III. At six months after retreatment, the average was - 0.36*1.08 D in group I, -0.42 ± 1.12 D in group II, and -1.40 ± 1.62 D in group III.

CONCLUSION: The amount and frequency of regression was higher in patients with high and extreme myopia; however, the preliminary results of retreatment of regression were satisfactory. [J Refract Surg 1998;14:S197-S198]
Comparison of 18% Ethanol and Mechanical Debridement for Epithelial Removal Before Photorefractive Keratectomy
Authors: Shah Sunil , Doyle S J , Chatterjee Anupam , Williams B E B , Ilango B
Published: April 2021

ABSTRACT

PURPOSE: To assess the safety of alcohol compared to mechanical debridement for epithelial removal prior to photorefractive keratectomy (PRK).

METHODS: Forty-one second eyes of 41 patients underwent epithelial removal using alcohol prior to PRK with a Nidek EC-5000 excimer laser. The results were compared with the results of the 41 first eyes of the same patients that had mechanical debridement.

RESULTS: Initial results showed that the alcohol treated group tended to stay slightly hyperopic but had less haze compared to the mechanical debridement group. The treating surgeons favored alcohol as the preferred method of epithelium removal.

CONCLUSIONS: Alcohol debridement is an effective procedure although algorithms may have to be altered to take into account the slightly different healing process postoperatively. [J Refract Surg 1998;14:S212-S214]
Corneal Transparency and Measurement of Corneal Permeability in Excimer Laser Photorefractive Keratectomy
Authors: Polunin G S , Kourenkov V V , Polunina E G
Published: April 2021

ABSTRACT

PURPOSE: To introduce an image analysis of the cornea in photorefractive keratectomy (PRK) for preoperative and early postoperative determination of changes in the condition of the cornea.

METHODS: Slit-lamp videography was used to evaluate the cornea. Microdensitometry of the corneal images was performed. The optic density of the anterior, middle, and posterior corneal layers was measured. Photorefractive keratectomy was performed with the Nidek EC-5000 excimer laser. We followed patients with different amounts of myopia (range, -1.00 to -20.00 D) classified into three groups, according to age. Each age group was divided into four subgroups depending on the amount of myopia.

RESULTS: The analysis of the microdensitometry results of the optic section of transparent corneas in myopic patients demonstrated differences depending on age and mean amount of myopia. A correlation between the microdensitometric data of permeability by fluorescein and the refractive results of PRK was found.

CONCLUSION: Quantitative image analysis of the cornea is a useful method to evaluate the condition of the cornea before and after PRK. This method can identify early damage to the cornea in myopic patients. Preoperative investigation of permeability of the cornea using fluorescein is an important method for selection of the patients for PRK. [J Refract Surg 1998;14:S230-S234]
Purse-string Sutures for Hyperopia Following Radial Keratotomy
Authors: Damiano Richard E , Forstot S Lance , Frank Cari J , Kasen Wesley B
Published: April 2021

ABSTRACT

BACKGROUND: Five years ago, we presented 19 procedures employing two intrastromal pursestring sutures to treat hyperopic shift following radial keratotomy. Thirty-four additional procedures and longer follow-up are now presented detailing the task of rehabilitating these eyes.

METHODS: Fifty-three eyes of 53 radial keratotomy patients who were unhappy with their uncorrected vision and who were dissatisfied with contact lens or spectacle correction underwent double corneal intrastromal purse-string suturing and were subsequently followed for at least 1 year. There were seven eyes with primary overcorrection and 46 eyes with progressive hyperopic shift. Spherical equivalent refraction before purse-string sutures ranged from +0.50 to +6.25 D (mean, +2.60 D, SD ± 1.26 D). Prior to purse-string suturing, uncorrected visual acuity ranged from 20/30 to 20/400 with 21 eyes (45.3%) 20/100 or worse.

RESULTS: The follow-up after suturing averaged 3.6 years (range, 1 to 10 yr). All patients had followup of at least 1 year. The steepening in average keratometric power was 2.94 ± 1.72 D (range, 1.06 to 6.68 D). The sherical equivalent refraction after suturing averaged -0.15 ± 1.17 D (range, +3.75 to -2.50 D). Uncorrected visual acuity after suturing was 20/40 or better in 38 eyes (72%) and 20/50 to 20/100 in 15 eyes (28%). The number of eyes with a spherical equivalent refraction of ±0.50 D with 0.50 D or less refractive astigmatism was 15 (26% of eyes). There were 34 eyes (66%) with ±1.00 D with 1.00 D or less of refractive astigmatism, and 42 eyes (78%) with ±2.00 D with 2.00 D or less refractive astigmatism. Most of the spread was on the myopic side, as intended. There were no significant intraoperative or postoperative complications. Fifteen eyes gained two or more lines of best spectacle-corrected visual acuity and no eyes lost one line.

CONCLUSION: Double intrastromal purse-string suturing produces steepening of the central cornea and reduces hyperopia after radial keratotomy. [J Refract Surg 1998;14:408-413]