bluuebunny/crossref_metadata_2025 huggingface dataset:
Failure of Mechanical Epithelial Removal to Reverse Persistent Hyperopia After Photorefractive Keratectomy
Authors: Gauthier Charline A , Fagerholm Per , Epstein Daniel , Holden Brien A , Tengroth Bjorn , Hamberg-Nystrom Helene
Published: April 2021

ABSTRACT

BACKGROUND: Residual hyperopic overcorrection after photorefractive keratectomy (PRK) using early algorithms is a rare but serious complication. Anecdotal evidence suggests that epithelial removal can stimulate epithelial hyperplasia, thereby reducing overcorrection. The aim of this study was to determine if epithelial removal effectively reduced hyperopia after PRK for myopia and, concurrently, to correlate the healing response with the refractive outcome.

METHODS: Enrolled were seven eyes of seven patients (mean age, 44 + 13 years) who had undergone PRK with a mean manifest refractive error of +2.21 ± 0.74 diopters (D). AU had undergone PRK an average of 24 + 9 months previously. Epithelial removal was performed over the excimer-treated zone with a surgical blade. Subjective refraction, epithelial thickness, corneal topography, and subepithelial haze were measured up to 1 year postoperatively.

RESULTS: Reduction in hyperopia between the baseline and 1-year visit was not statistically significant (mean difference, 0.55 D reduction; p=.102). That epithelial removal did not stimulate a woundhealing response is further supported by the absence of change in epithelial thickness over the first month and the small amounts of subepithelial haze. Central corneal power was reduced by a mean of 0.64 D after 1 month (p<.05).

CONCLUSIONS: Epithelial removal alone did not reduce the hyperopic overcorrection present after PRK, nor did it stimulate epithelial hyperplasia in the majority of these eyes. However, a trend toward improvement was noted with time was noted. [J Refract Surg. 1996;12:601-606.]
Bacterial Keratitis After Photorefractive Keratectomy
Authors: Amayem Ashraf , Ali Ahmed Tawfik , Waring George O , Ibrahim Osama
Published: April 2021

ABSTRACT

Two patients who had excimer laser photorefractive keratectomy (PRK) for myopia developed bacterial keratitis, one from Staphylococcus epidermidis and the other with a negative culture. Both were treated with topical antimicrobial agents. One eye recovered an uncorrected visual acuity of 20/20. The other was left with a moderate subepithelial scar and an uncorrected visual acuity of 20/150. [J Refract Surg. 1996;12:642-644.]
Laser in situ Keratomileusis for Simple Myopic, Mixed, and Simple Hyperopic Astigmatism
Authors: Chayet Arturo S , Magallanes Roberto , Montes Miguel , Chavez Salvador , Robledo Nora
Published: April 2021

ABSTRACT

PURPOSE: To summarize initial results of astigmatic laser in situ keratomileusis (LASIK) for 41 eyes of 26 patients using the EC-5000 Nidek system and assess its safety, efficacy and predictability.

METHODS: The EC-5000 Nidek excimer laser was used to correct simple myopic, mixed, and simple hyperopic astigmatism with manifest cylinder from 2.00 to 6.50 D. Ablation zone diameters were 6.5 mm (steep meridian ablation) to 7.5 mm (flat meridian ablation) with a repetition rate of 40-41 Hz. In eyes with simple myopic and mixed astigmatism, ablation was performed in both meridians; in eyes with simple hyperopic astigmatism, ablation was performed in the flat meridian alone. Followup was 3 months in all eyes.

RESULTS: Uncorrected visual acuity was 20/40 or better in 85% of the eyes. Uncorrected visual acuity was equal to the preoperative spectacle-corrected visual acuity in 63% of the eyes. Intended cylinder correction was within 1.00 D in 95% of eyes. No eyes lost lines of spectacle-corrected visual acuity.

CONCLUSION: LASIK using the EC-5000 excimer laser appears to be effective in the treatment of simple myopic, mixed, and simple hyperopic astigmatism, with favorable results as compared to those previously described for astigmatic keratotomy. [J Refract Surg 1998;14:S175-S176]
Angle-fixated Anterior Chamber Phakic Intraocular Lens for Myopia of -7 to -19 Diopters
Authors: Baikoff George , Arne Jean L , Bokobza Yves , Colin Joseph , George Jean L , Lagoutte Francoise , Lesure Pierre , Montard Michel , Saragoussi Jean J , Secheyron Patrick
Published: April 2021

ABSTRACT

PURPOSE: To assess the safety and efficacy of a second generation, anterior chamber phakic intraocular lens (Baikoff Model ZB5M) in patients with high myopia.

METHODS: One hundred and twenty-one patients (134 eyes) with myopia of -7.00 to -18.80 D were implanted with the ZB5M lens and followed for 18 to 52 months; the number of eyes evaluated was: 6 months (104 eyes), 1 year (91 eyes), 18 months (78 eyes), 2 years (68 eyes), and 3 years (35 eyes).

RESULTS: Postoperative spherical equivalent refraction averaged -1.00 D and the error in refractive correction (achieved minus intended) averaged -0.40 D during the first 2 years, increasing -to -1.30 D refraction and -0.60 D error in refractive correction at 3 years. At 2 years, approximately 40% of eyes had a spherical equivalent refraction within ±0.50 D, and 65% within ±1.00 D. The uncorrected distance visual acuity was 0.048 at baseline and 0.5 at 3 years; near visual acuity was 0.21 at baseline and approximately 0.7 over the 3 years of follow-up. Spectacle-corrected distance visual acuity at baseline was 0.54; it improved to 0.7. Near visual acuity was 0.65 at baseline and it improved to approximately 0.75. Endothelial cell counts in the central and peripheral cornea were reduced by an average 3.3% at 6 months, declining an additional 1% to 2% over the remaining follow-up period. Regression analyses indicated that most of the endothelial cell loss was due to surgery. Additional complications included halos/glare in 37 of 133 eyes (27.8%) and iris retraction with pupillary ovalization in 30 of 133 eyes (22.6%). The intraocular lens was exchanged in four of 133 eyes (3.0%) and removed in three of 133 eyes (2.3%), the latter because of halos (one eye) and a flat anterior chamber with severe inflammation (two eyes).

CONCLUSIONS: Implantation of the Baikoff ZB5M lens in the anterior chamber of phakic eyes significantly reduced high myopia and produced a stable refractive outcome over the 3 years, accompanied by marked improvement in uncorrected distance visual acuity and minimal, non-progressive damage to the corneal endothelium. Frequent complications included pupillary ovalization and halos/glare. Improvements in accuracy of IOL power calculations are needed. [J Refract Surg 1998;14:282-293]
Mycobacterium Chelonae Keratitis Following Laser in situ Keratomileusis
Authors: Reviglio Victor , Rodriguez Mabel L , Picotti Gabriela S , Paradello Martin , Luna José D , Juárez Claudio P
Published: April 2021

ABSTRACT

Corneal infection after laser in situ keratomileusis (LASIK) is rare. However, surgical trauma or breakdown of epithelium increases the risk of surface infection. We present the case of a 45 year old woman who developed keratitis due to Mycobacterium chelonae 1 month after LASIK with the Mini-Laser Sight 2000 excimer laser. After an initial improvement following antibiotic therapy the infection progressed until it was necessary to perform penetrating keratoplasty, with a successful result. [J Refract Surg 1998;14:357-3601
A Quantitative Corneal Topography Index for Detection of Keratoconus
Authors: Dastjerdi Mohammad H , Hashemi Hassan
Published: April 2021

ABSTRACT

BACKGROUND: Detection of keratoconus has become a critical issue in patients who are potential candidates for refractive surgical procedures. In eyes with early stages of keratoconus, slit-lamp corneal changes are either absent or too subtle for detection, and keratometry may be normal. Videokeratography systems have greater sensitivity for detection of such cases, but interpretation of the topographic map is sometimes difficult, especially when pathologies with similar topographic patterns are suspected. We introduce an index using corneal topography for detection of keratoconus.

METHODS: From March 1994 to December 1995, a total of 513 unoperated eyes, with no pathology other than keratoconus, from 283 consecutive patients were categorized into three groups based on slit-lamp examination and corneal topographic findings. Those with clinically obvious keratoconus were placed in the first group (53 eyes [10.3%]), those with keratoconus suspect comprised the second group (17 eyes [3.3%]), and the third group was that of normal eyes (443 eyes [86.4%]). In all videokeratographs of these eyes, the highest rate of corneal power changes (in diopters per millimeter) away from the apex (the point of maximum power) to the periphery was measured along its semimeridian. This index, called the "highest rate of steepening (HRS)", was statistically analyzed in the three groups.

RESULTS: The mean ± SD of highest rate of steepening was 3.60 ± 1.70 D/mm (range 1.59 to 7.53 D/mm) in the clinically obvious keratoconus group, 1.59 ± 0.21 D/mm (range 1.35 to 1.98 D/mm) in the keratoconus suspect group, and 0.72 ± 0.31 D/mm (range 0.18 to 1.63 D/mm) in normal eyes. There was a highly statistically significant difference in the means of highest rate of steepening in the three groups (p < 0.0001). A small overlap in the highest rate of steepening ranges was shown among the three groups. Considering the first and second groups as cases of keratoconus, and 1.40 D/mm as the optimum cut-off value for highest rate of steepening, a sensitivity of 95.7% (67 out of 70 cases were detected), a specificity of 96.4% (16 false-positive cases), and an accuracy of 96.3% was obtained.

CONCLUSION: The highest rate of steepening may be a useful measure for keratoconus screening with videokeratography. Validation is needed to evaluate its accuracy. [J Refract Surg 1 998; 14:427-436]
Tenascin and Cytokines in Tear Fluid After Photorefractive Keratectomy
Authors: Vesaluoma Minna H , Tervo Timo T
Published: April 2021

ABSTRACT

BACKGROUND: Basic knowledge of the substances involved in wound healing after photorefractive keratectomy (PRK) is essential for development of pharmacological intervention. We present preoperative and postoperative analysis of tear fluid extracellular matrix proteins and cytokines after PRK.

METHODS: Tear fluid samples from 70 patients (72 eyes) who had PRK (38 women and 32 men, mean age 31.5 yr) were studied. Samples from 18 patients (18 eyes) were analyzed in two different studies.

RESULTS: Mean preoperative tear fluid flow in the collection capillary (volume divided by tear collection time) varied from 4.5 to 22.5 µ?/min in five series of patients. It increased significantly during the first two postoperative days (range of means, 55.5 to 88.8 µ? min, ? < 0.01), and decreased to the preoperative level by day 7 (range of means, 9.7 to 18.2 µ?/min). The tenascin and cytokine release rates increased significantly during the first two days after PRK and returned to the preoperative level by day 7. Mean ± standard error for tenascin: day 0 (5.2 ±1.9 ng/min); day 2 (22.7 ±6.1 ng/min; p=0.02). Mean ± standard error for HGF: day 0 (3.2 ± 0.7 pg/min); day 1 (22.8 ± 4.2 pg/min; p=0.0003). Mean ± standard error for TGF-ßl: day 0 (63.3 ± 19.6 pg/min); days 1-2 (826.2 ± 253.7 pg/min; p=0.001). Mean ± standard error for VEGF: day 0 (166.0 ± 29.6 pg/min); days 1-2 (824.4 ± 165.1 pg/min; p=0.0007). Mean ± standard error for PDGF-BB: day 0 (0.42 ± 0.19 pg/min); day 2 (27.6 ± 5.8 pg/min; p=0.0000). Mean ± standard error for TNF-a: day 0 (9.5 ± 2.6 pg/min); day 2 (28.6 ± 5.9 pg/min; p=0.003). Excluding PDGF-BB, all substances studied were present in normal human tear fluid. PDGF-BB was present in only 17% of the preoperative samples.

CONCLUSION: Corneal wounding induces an increased release of several growth modulating cytokines which may be involved in healing processes. [J Refract Surg 1998;14:447-4541
Prospective Bilateral Study of Night Glare After Laser in situ Keratomileusis With Single Zone and Transition Zone Ablation
Authors: El Danasoury M Alaa
Published: April 2021

ABSTRACT

PURPOSE: Evaluation of night glare after excimer laser in situ keratomileusis (LASIK) using two different ablation zone diameters.

METHODS: One hundred and twenty eyes of 60 consecutive myopic patients received LASIK with the Nidek EC-5000 excimer laser. Eyes were randomized so that every patient had a single ablation zone of 5.5 mm on one eye and an ablation zone of 5.5 mm with a transition zone of 1.0 mm diameter larger on the other eye. Night glare was measured by two methods; a spot light test and a subjective questionnaire.

RESULTS: At 6 months, 54 patients (90%) were examined; results of the spot light test showed that 40 patients (74.1%) perceived more glare with the eye with the single ablation zone; the subjective questionnaire indicated that 22 patients (40.7%) had more night glare with the eye with a single ablation zone compared to the other eye. The use of the transition zone increased the required total ablation depth by 20%.

CONCLUSION: The use of a peripheral transition 1.0 mm diameter larger than the ablation zone significantly decreased night glare after LASLK with slight increase in the required central ablation depth. [J Refract Surg 1998;14:512-516]
Lamellar Refractive Surgery with Scanned Intrastromal Picosecond and Femtosecond Laser Pulses in Animal Eyes
Authors: Kurtz Ron M , Horvath Christopher , Liu Hsiao-Hua , Krueger Ronald R , Juhasz Tibor
Published: April 2021

ABSTRACT

PURPOSE: To evaluate the use of scanned intrastromal picosecond and femtosecond laser pulses in lamellar refractive surgical procedures.

METHODS: Intrastromal corneal photodisruption was performed in fresh porcine and primate cadaver eyes with a solid-state femtosecond laser. Laser pluses were focused 150 to 200 um below the epithelial surface and scanned in a spiral pattern to create a plane. A flap was made by scanning an arc pattern from the plane of the spiral to the surface of the cornea. Tissue plane separation was graded using a standard scale, while internal surfaces were analyzed by scanning electron microscopy. Comparison was made to a picosecond laser system using the same delivery system device. Creation of a stromal lenticule for in situ keratomileusis was also demonstrated and compared with both laser systems.

RESULTS: For femtosecond pulses, tissue separation was achieved best with pulse energies from 4 to 8 µl and spot separations from 10-15 µm. Picosecond pulses accomplished less complete separations with pulse energies of 25 uJ and spot separations from 10 to 20 µp?. Surface quality corresponded to dissection results, with high-grade dissections resulting in a smooth surface appearance, versus a more irregular surface for low-grade dissections. Although high-grade dissections could be created with picosecond pulses (with optimal parameters) in ex vivo porcine eyes, only femtosecond parameters produced similar results in ex vivo primate eyes.

CONCLUSION: In contrast to previous attempts using picosecond lasers which require additional mechanical dissection, high precision lamellar refractive surgery may be practical with femtosecond laser pulses. [J Refract Surg 1998;14:541-548]
Perioperative Microbiologic Profile of the Conjunctiva in Photorefractive Keratectomy
Authors: Barequet Irina S , Jabbur Nada S , Barron Yolanda , Osterhout Gerard J , O'Brien Terrence R
Published: April 2021

ABSTRACT

PURPOSE: Therapeutic soft contact lenses are used commonly as an adjunctive treatment after photorefractive keratectomy (PRK) to decrease postoperative pain caused by the movement of lids over the corneal epithelial defect and to facilitate epithelial healing. We assessed the microbiological profile of the conjunctiva of patients undergoing PRK for myopia, before and after the concurrent use of a therapeutic soft contact lens, and compared the effect on ocular bacterial colonization of prophylactic administration of topical tobramycin 0.3% versus ofloxacin 0.3%.

METHODS: Forty-three consecutive eyes from 37 patients underwent PRK for myopia or myopic astigmatism. Eyes were assigned randomly to prophylactic antibacterial treatment with either topical ofloxacin 0.3% or tobramycin 0.3%, applied prior to surgery and three times daily after surgery until therapeutic soft contact lens removal. Material from the conjunctival sac was obtained for bacteriologic cultures prior to surgery. Clinical evaluation of all eyes was conducted prospectively. Three days after PRK, the therapeutic soft contact lenses were removed and cultured. Cultures from the conjunctival sac were then repeated.

RESULTS: No statistically significant differences were observed in culture positivity between the two groups of eyes, in spite of some positive preoperative and postoperative cultures. Only one out of 43 eyes (assigned to the ofloxacin group) developed a peripheral corneal infiltrate. The corneal infiltrate healed completely without sequelae using antibiotic and corticosteroid therapy.

CONCLUSIONS: The use of therapeutic soft contact lenses after PRK with either topical tobramycin 0.3% or ofloxacin 0.3% were well tolerated. However, perioperative positive conjunctival cultures were relatively frequent and prophylactic antibiotics should be used in the setting of an epithelial defect and therapeutic soft contact lens following PRK. [J Refract Surg 2001;17:55-62]
Laser in situ Keratomileusis for the Correction of Hyperopia From +0.50 to +11.50 Diopters With the Keracor 117C Laser
Authors: Tabbara Khalid F , El-Sheikh Hisham F , Islam S M Monowarul
Published: April 2021

ABSTRACT

PURPOSE: To evaluate excimer laser in situ keratomileusis (LASIK) for the correction of hyperopia.

METHODS: We reviewed retrospectively the medical records of 46 patients treated with LASIK for hyperopia. All patients had a complete ophthalmologic evaluation. The corneal bed was ablated using the Bausch & Lomb Chiron Keracor 117C excimer laser to create a paracentral annular ablation under a nasally hinged 160-µm corneal flap with the Chiron Automatic Corneal Shaper microkeratome. Follow-up was a minimum of 6 months.

RESULTS: Eighty eyes of 46 patients (23 males and 23 females) were included. Age ranged from 18 to 65 years (mean, 42 yr). The range of preoperative spherical equivalent refraction was +0.50 to +11.50 D (mean, +3.40 D). Mean postoperative spherical equivalent refraction at 6 months was +0.26 D. Six months after surgery, 35 eyes (44%) achieved uncorrected visual acuity of 20/20 or better and 78 eyes (97.5%) achieved 20/40 or better. Forty-six eyes (58%) had a postoperative spherical equivalent refraction within ±0.50 D of attempted correction, and 67 eyes (84%) were within ±1.00 D of attempted correction. When using the Bausch & Lomb Chiron Keracor 117C excimer laser to correct hyperopia, eyes with a spherical equivalent refraction less +2.00 D should be overcorrected by 25%, +2.00 to +4.00 D by 30%, and over +4.00 by 40%. The positive cylinder should, be overcorrected by 10%.

CONCLUSIONS: LASBS was safe and effective in the treatment of hyperopia from +0.50 to +11.50 D. Regression following LASIK for hyperopia remains a problem. A special nomogram was required to achieve results comparable with those for myopia. [J Refract Surg 2001;17:123-128]
Prevention of Corneal Ectasia in Laser in situ Keratomileusis
Authors: Vinciguerra Paolo , Camesasca Fabrizio I
Published: April 2021

ABSTRACT

PURPOSE: Ectasia after laser in situ keratomileusis (IASIK) is a rare but serious complication. Prevention includes proper patient selection with detection of those at particular risk. Causes of ectasia include predisposition, excessive ablation with less than 250 µt? of residual stromal bed, thicker than normal flap, irregular corneal thickness, and different ablation rates.

METHODS: We evaluated corneal curvature patterns and their relationship to corneal topography and pachymetry maps.

RESULTS: Corneal topography (axial, tangential, and altimetric) and pachymetry map characteristics of normally astigmatic corneas, keratoconus, false-positive and false-negative cases, as well as contact lens-induced warpage are discussed.

CONCLUSIONS: Preoperative pachymetry maps for LASIK surgery allow accurate case selection through detection of borderline cases, and provide important documentation of preoperative status, as well as useful information for improving surgical strategy. Another important parameter is the asphericity index. [J Refract Surg 2001;17(suppl): S187-S189]
Interface Fluid and Diffuse Corneal Edema After Laser in situ Keratomileusis
Authors: Portellinha Waldir , Kuchenbuk Marcio , Nakano Kozo , Oliveira Marivaldo
Published: April 2021

ABSTRACT

PURPOSE: To report a new complication of interface fluid accumulation and corneal edema in an uneventful laser in situ keratomileusis (LASIK) procedure.

METHODS: Uncomplicated bilateral LASIK for myopia using the Hansatome microkeratome was performed. One day postoperatively, the patient noted decreased visual acuity. The topical corticosteroid was changed from dexamethasone to prednisolone acetate 1% every 2 hours. Two weeks later the patient reported worsening visual acuity in both eyes. Uncorrected visual acuity was 20/200 in the right eye and 20/100 in the left. Slit-lamp biomicroscopy indicated significant fluid build-up in the interface. Intraocular pressure (IOP) by Goldmann applanation tonometry was 15 mmHg in the right eye and 14 mmHg in the left.

RESULTS: After 4 weeks, intraocular pressure by bidigital pressure was increased and high. The corticosteroid was discontinued and antiglaucoma medication lowered the intraocular pressure, which resulted in corneal clearing and disappearence of interface fluid in both eyes.

CONCLUSIONS: Early recognition of this new complication of LASHi is necessary. The falsely low reading of IOP in the setting of interface fluid was the result of easy compressibility of the fluid-filled space and reflects the pressure of the interface fluid. This apparently low IOP reading can be an additional sign of the existence of interface fluid. The corticosteroid should be discontinued and antiglaucoma medication instituted. This should lead to a lowering of intraocular pressure and result in corneal clearing and disappearence of the interface fluid with improvement in visual acuity. [J Refract Surg 2001;17(suppl):S192-S1951
Management of Corneal Epithelial Defects Following Laser in situ Keratomileusis
Authors: Smirennaia Elena , Sheludchenko Viatcheslav , Kourenkova Natalia , Kashnikova OIesja
Published: April 2021

ABSTRACT

PURPOSE: To determine the main principles of postoperative management in patients with epithelial defects following LASHC

METHODS: Patients with myopia and myopic astigmatism (N=2972; refraction from -1.25 to -15.50 D) were treated with the Nidek EC-5000 excimer laser, using the Chiron Vision HT-230 Hansatome microkeratome. We observed 95 cases with intraoperative epithelial damage among 5896 operations (1.6%) . Patients received traditional topical medical treatment (Tobramycin 0.3%, five times a day; Lacrisifi, six to eight times a day). In eyes with an epithelial defect lees then 3 mm, no additional medical care was needed. In eyes with epithelial defects more then 3 mm, soft therapeutic contact lenses were used until total re-epithelialization occurred.

RESULTS: Total re-epithelialization was observed the day following surgery in patients with small defects (less then 3 mm). Visual acuity achieved preoperative level 4 to 7 days after surgery. Total re-epithelialization in patients with soft contact lenses occurred 1 to 3 days after LASHL On the next day examination, Solcoseryl 20% eye gel was added to topical therapy for corneal healing. In these patients visual acuity achieved preoperative level 10 to 14 days after surgery. In three eyes with large epithelial defects (4 to 5 mm), irregular astigmatism (one eye; 0.02%) or against-therule astigmatism (two eyes; 0.03%) occurred. Patients complained of blurred and double vision. Transepithelial phototherapeutic keratectomy was performed after 3 months for epithelial smoothing, with good visual results.

CONCLUSION: Management of epithelial defects following LASHC can be concentrated on avoiding epithelial hyperplasia. Epithelial defects less than 3 mm do not appear to produce epithelial hyperplasia. Irregular astigmatism induced by LASHC can result in reduced best spectacle-corrected visual acuity. A common cause of irregular astigmatism is corneal epithelial remodeling and corneal thickening secondary to corneal epithelial defects created at the time of the LASHC procedure. [J Refract Surg 2001;17(suppl):S196-S199]
Photorefractive Keratectomy With Customized Segmental Ablation to Correct Irregular Astigmatism After Laser in situ Keratomileusis
Authors: Gimbel Howard V , Stoll Stuart B
Published: April 2021

ABSTRACT

PURPOSE: To correct irregular astigmatism after laser in situ keratomileusis (LASIK) with customized segmental ablation using the Nidek OPD-Scan (ARK-10000) to guide the Nidek EC-5000 excimer laser with the Final Fit software.

METHODS: One eye of a patient that had undergone LASIK and one enhancement was treated using photorefractive keratectomy (PRK) with customized segmental ablation. OPD-Scan maps were analyzed before and after surgery. The Final Fit software was used to link the OPD-Scan to the EC-5000 laser to guide the customized ablation.

RESULTS: At 1 month postoperatively, best spectacle-corrected visual acuity had improved from 20/20-2 to 20/15-2, the patient's subjective evaluation of vision was markedly improved, and the postoperative OPD-Scan maps appeared more regular.

CONCLUSION: Customized segmental ablation can be performed using the Nidek OPD-Scan and Final Fit software to improve best spectaclecorrected visual acuity and minimize irregular astigmatism, which may result from prior surgical procedures. [J Refract Surg 200l;17(suppl): S229-S232]
Intraocular Lens Implantation and Laser in situ Keratomileusis (Bioptics) to Correct High Myopia and Hyperopia With Astigmatism
Authors: Velarde José I , Anton Paula G , de Valentin-Gamazo Luis
Published: April 2021

ABSTRACT

PURPOSE: To analyze the refractive outcome of moderate to high myopic and hyperopic patients with astigmatism who underwent programmed refractive surgery; first lens phacoemulsification with intraocular lens implantation and 3 months later, laser in situ keratomileusis (LASIK).

METHODS: Four men and eight women (22 eyes) with a mean age 47.3 years (range, 38 to 75 yr), and an average spherical equivalent refraction of -11.76 D and +5.22 D and (range, -17.50 to +8.50 D) underwent two refractive procedures. First, phacoemulsification of the lens with a self-sealing incision through clear cornea on the steepest topographic axis and implant of a monofocal intraocular lens in the bag was performed by two experienced surgeons. Second, LASLK was performed with the Nidek EC-5000 excimer laser and the Moria LSK-One microkeratome, by one surgeon. Eyes were divided into two different groups. In the first group, the IOL implanted was calculated to leave the eye slightly myopic, with final correction to be achieved with LASLK. In the second group, the IOL implanted was calculated to achieve emmetropia, correcting any residual refractive error with the laser.

RESULTS: After surgery, mean spherical equivalent refraction was +0.26 D (range, -0.375 to +1.50 D). Predictability of refractive outcome: 0 to -1.00 D, 63.63%; +0.25 to +1.00 D, 31.80%; +1.25 to +2.00 D, 4.54%. Mean residual refractive astigmatism was 0.30 D (range, 0 to 1.50 D). Uncorrected visual acuity of 20/20 or better was achieved in 18.3% of eyes; 20/40 or better in 81.8%. No eyes lost two or more Snellen lines of visual acuity and no adverse effects were observed.

CONCLUSIONS: Bioptics (phacoemulsification with IOL implantation followed 3 months later by LASLK with the Nidek EC-5000 excimer laser) for correction of moderate to high myopia and hyperopia, with astigmatism, enabled us to treat the total refractive error and adjust final outcomes. [J Refract Surg 2001;17(suppl):S234]
Comparison of Laser in situ Keratomileusis Outcomes With the Nidek EC-5000 and LSX LaserSight Excimer Lasers
Authors: Merchea Mohan , Tokarewicz Al
Published: April 2021

ABSTRACT

PURPOSE: To report the results of laser in situ keratomileusis (LASIK) for myopia with and without astigmatism using the Nidek EC-5000 and LaserSight LSX excimer laser systems.

METHODS: A retrospective analysis of refractive outcomes with each laser was conducted. Approximately 2900 myopic and astigmatic treatments up to -10.00 D (spherical equivalent refraction) were analyzed using refractive outcomes analysis software.

RESULTS: At 6 months postoperatively, 78% of patients treated with the Nidek EC-5000 laser and 53% of patients treated with the LaserSight LSX laser were within ±0.50 D of the intended correction.

CONCLUSION: A difference in safety, stability, and efficacy of LASIK was found that favored the Nidek EC-5000 excimer laser. [J Refract Surg 2001;17(suppl):S246-S249]
Experience With the Nidek MK-2000 Microkeratome in 1220 Cases
Authors: Sarkisian Karen A , Petrov Aleksey A
Published: April 2021

ABSTRACT

PURPOSE: To evaluate the performance of the Nidek MK-2000 microkeratome.

METHODS: The Nidek MK-2000 microkeratome was used in 1220 cases of LASDC with the Nidek EC-5000 excimer laser. Patients had a wide range of myopia (-0.75 to -25.00 D), hyperopia (+0.75 to +9.00 D) and/or astigmatism (-7.00 to +6.50 D). The flap was created with the 130-µm microkeratome plate for 859 eyes, and the 160-µm plate for 361 eyes. In 632 eyes, the 8.5-mm ring was used, and the 9.5-mm ring was used in 588 eyes. The flap hinge was placed nasally, superiorly, or inferiorly depending on the needs of the case. An easy external modification allowed us to gently increase and decrease the vacuum level and to perform the procedure using a low vacuum regimen, if necessary.

RESULTS: The edges of the flaps and the corneal surface were of good quality in all eyes. No free flaps were noted. One case was aborted because of inappropriate flap formation in a patient with a large difference (6.50 D) in corneal curvature in two main meridians. This patient successfully underwent LASDi 1 month later, placing the flap hinge in the opposite direction. Small epithelial shrinkage was noted in 38 eyes. No other flap complications were noted. In all patients the flap diameter and thickness were close to that estimated by the manufacturer. The vacuum level was adequate and stable in all cases.

CONCLUSION: The Nidek MK-2000 microkeratome was easy to use, predictable, and safe. However, we suggest a modification, adding an adjustable head movement to create wider hingeto-center-of-pupil distance and an additional 9.0-mm suction ring. [J Refract Surg 2001; 17(suppl):S252-S254].
Anterior Corneal Optical Aberrations Induced by Photorefractive Keratectomy for Hyperopia
Authors: Oliver Katherine M , O'Brart David P S , Stephenson Christopher G , Hemenger Richard P , Applegate Raymond A , Tomlinson Alan , Marshall John
Published: April 2021

ABSTRACT

PURPOSE: Photorefractive keratectomy (PRK) for hyperopia requires both a steepening of the central cornea and a flattening of the mid-periphery to achieve its effect and is likely to affect the optical aberrations of the eye.

METHODS: Nine patients underwent PRK to correct between +2.00 and +4.00 D of hyperopia (first eye treated for each patient) using the Summit Technology Apex Plus excimer laser. Anterior corneal aberrations for pupil diameters of 3, 5.5 and 7 mm were estimated from corneal topography data (TMS-I), assuming a uni-index, single surface cornea. Refractive error was assessed using retinoscopy and standard subjective tests.

RESULTS: Apart from the intended change in refraction (mean spherical equivalent manifest refraction, +4.60 ? 1.60 D before surgery and +0.70 ? 1.60 D at 1 year after surgery), the most significant change was in spherical aberration. Anterior corneal spherical aberration was positive (+1.60 ? 0.60 D for a 5.5-mm pupil) before surgery and became negative after surgery (-1.80 ? 1.20 D at 1 year). The change in spherical aberration was related to the achieved change in refractive error.

CONCLUSIONS: The large change (approximately 3.00 D) in spherical aberration (from positive to negative aberration) has implications for the optical performance of the whole eye, where the effects of lenticular aberration must also be considered. [J Refract Surg 2001;17:406-413]
Corneal Temperature Changes During Photorefractive Keratectomy Using the Laserscan 2000 Flying Spot Laser
Authors: Vetrugno Michele , Maino Anna , Valenzano Emanuele , Cardia Luigi
Published: April 2021

ABSTRACT

PURPOSE: To evaluate the thermal variations during photorefractive keratectomy (PRK) induced by a Laserscan 2000 flying spot excimer laser.

METHODS: Thermal changes during PRK were recorded using a non-contact infrared thermometer on 58 eyes with an attempted correction ranging from -1.25 to -9.00 D. The eyes were randomly divided into two groups to test the thermal effects of two different ablation scan techniques: sequential and randomized modes. Thermal measurements were also performed during myopic ablations on polymethylmethacrylate (PMMA) test plates.

RESULTS: On PMMA plates, a significant relationship between the amount of attempted myopic correction and thermal changes was established (P=.017 in sequential mode and P=.0O7 in randomized mode); this was not established for human eyes. With the sequential mode, an unexpected cooling effect after PRK was reported for each myopia subgroup (P=.003 in the low and high myopia subgroups, P-cOOl in the medium myopia subgroup). With the randomized mode, the cooling effect was detected only for low amounts of myopia.

CONCLUSION: Despite a high repetition rate, the Laserscan 2000 flying spot laser minimized thermal shock. In comparison with randomized (nonsequential) pulse application, sequential pulsing showed no increase in the thermal loading of corneas. In fact, a cooling effect during PRK was produced. [J Refract Surg 2001;17:454-459]
Broad Beam vs. Flying Spot Excimer Laser: Refractive and Videokeratographic Outcomes of Two Different Ablation Profiles After Photorefractive Keratectomy
Authors: Fiore Tito , Carones Francesco , Brancato Rosario
Published: April 2021

ABSTRACT

PURPOSE: To assess the refractive outcomes and videokeratographic patterns in photorefractive keratectomy (PRK) of two last-generation excimer lasers: broad beam and flying spot lasers.

METHODS: Forty eyes were treated for a mean myopic correction of -5.59 ± 2.17 D with a Ladarvision excimer laser (Autonomous Technology Corp). We compared the refractive outcomes and the videokeratographic patterns with those of 40 eyes treated with the Summit Apex Plus laser (Summit Technology Ine) for a mean myopic correction of -5.60 ± 2.24 D.

RESULTS: During the 6-month follow-up, we found no significant difference in uncorrected and spectacle-corrected visual acuity, haze grade, regularity index, or decentration. The eyes treated by Ladarvision showed a lower refractive error at 1 month (P - .04), a lower incidence of central islands at 1 (P = .003) and 3 months (P = .04), a wider mean effective ablation area at 1 (P = .0004), 3 (P = .0000009), and 6 months (P = .0000000004), a less steep ablation edge at 1 (P = .0026), 3 (P = .015), and 6 months (P = .011).

CONCLUSIONS: The small beam excimer laser provides better videokeratographic outcomes, which lead to quicker refractive stability and better visual performance. [J Refract Surg 2001;17: 534-541]
Spot Size and Quality of Scanning Laser Correction of Higher Order Wavefront Aberrations
Authors: Huang David , Arif Muhammad
Published: April 2021

ABSTRACT

PURPOSE: To investigate the effect of laser spot size on the outcome of aberration correction with scanning laser corneal ablation.

METHODS: Numerical simulation of ablation outcome.

RESULTS: Correction of wavefront aberrations of Zernike modes from second to eighth order were simulated. Gaussian and top-hat beams of 0.6 to 2.0-mm full-width-half-maximum diameters were modeled. The fractional correction and secondary aberration (distortion) were evaluated. Using a distortion/correction ratio of less than 0.5 as a cutoff for adequate performance, we found that a 2 mm or smaller beam is adequate for spherocylindrical correction (Zernike second order), a 1 mm or smaller beam is adequate for correction of up to fourth order Zernike modes, and a 0.6 mm or smaller beam is adequate for correction of up to sixth order Zernike modes.

CONCLUSIONS: Since ocular aberrations above Zernike fourth order are relatively insignificant, current scanning lasers with a beam diameter of 1 mm or less are theoretically capable of eliminating most of the higher order aberrations of the eye. [J Refract Surg 2001;17:S588-S591]
Objective Measurement of Wavefront Aberrations With and Without Accommodation
Authors: Pallikaris Ioannis G , Panagopoulou Sophia I , Siganos Charalambos S , Molebny Vasilys V
Published: April 2021

ABSTRACT

PURPOSE: The measurement of the refractive error profile is more useful than corneal topography in understanding the complexities of refractive surgery. We report on experimental studies of the spatially resolved refractometer Tracey-1, developed in Ukraine by IBME in medical cooperation with VEIC, Greece.

METHODS: Ten eyes were subjected to dynamic measurement of accommodation, in order to test the effectiveness of Tracey refractometry. Measurements were performed in zones 0 to 6 mm. The refractive aberrations were calculated and accommodation was evaluated.

RESULTS: Evaluation of data shows that the instrument can effectively follow the dynamic change of refractive aberrations through the accommodation process.

CONCLUSION: Clinical tests of Tracey technology demonstrated the ability to investigate accommodation using this instrument. [J Refract Surg 2001;17:S602-S607]
Choice of Spatial Frequency for Contrast Sensitivity Evaluation After Corneal Refractive Surgery
Authors: Montés-Micó Robert , Charman W Neil
Published: April 2021

ABSTRACT

PURPOSE: To study the utility of measurements of contrast sensitivity at different spatial frequencies as an index of visual recovery following refractive surgery.

METHODS: Contrast sensitivity at 1.5, 3, 6, 12, and 18 c/deg was measured with the Stereo Optical FACT chart in 20 patients after photorefractive keratectomy (PRK) using the Nidek EC-5000 excimer laser system, and in 18 patients following laser in situ keratomileusis (LASER). Contrast sensitivity was measured preoperatively and 1, 3, 6, and 12 months after surgery.

RESULTS: Results showed a statistically significant reduction (P<01) in contrast sensitivity at all spatial frequencies in PRR patients during the first and third month, but contrast sensitivity recovered to preoperative values by 6 months after surgery (P>.1). In LASIK patients, decreased contrast sensitivity values 1 month after surgery were also obtained at all spatial frequencies. After 3 mouths, contrast sensitivity at 1.5 and 3 c/deg had recovered and did not differ significantly from preoperative values (P>.1), although contrast sensitivity at other frequencies remained reduced (P<.01). At 6 and 12 months, contrast sensitivity at all spatial frequencies did not differ from that obtained preoperatively (P>.1).

CONCLUSIONS: Contrast sensitivity measurements at 6 and 12 c/deg appear to be most useful in the assessment of patients who have undergone laser refractive surgery because defocus and optical aberrations primarily affect the higher spatial frequencies. [J Refract Surg 2001;17:646-651]
Effect of Photorefractive Keratectomy for Myopia on Measurement of Retinal Nerve Fiber Layer Thickness Using Optical Coherence Tomography
Authors: Carpineto Paolo , Ciancaglini Marco , Zuppardi Eduardo , Doronzo Emanuele , Di Stefano Nicola , Mastropasqua Leonardo
Published: April 2021

ABSTRACT

PURPOSE: To evaluate the effect of excimer laser photorefractive keratectomy (PRK) on nerve fiber layer thickness measurements by optical coherence tomography in myopic eyes.

METHODS: Twenty-two patients who had PRK for myopia underwent nerve fiber layer measurement by optical coherence tomography in both eyes before and 6 months after surgery in the first operated eye and before surgery in the fellow (control) eye, 6 months after the first PRK. Optical coherence tomography was performed with a Humphrey Optical Coherence Tomography Scanner. Each eye was scanned at the nerve head program radius of 1.5. For each of the optical coherence tomography parameters (average for each quadrant, superior, inferior, temporal, nasal; average for each clock hour; average over the entire cylindrical section), descriptive statistics were calculated. The difference between the observed change from the first to the second examination was calculated between the treated and the control eye. Individual mean differences were tested with Student's f-test. Hotelling's T-squared generalized means test was used to determine whether the set of mean differences was equal to zero.

RESULTS: The average preoperative refractive error was -3.90 ? 1.50 D in treated eyes and -3.89 ? 1.50 D in control eyes (P = .Sl, Student's /-test). Mean achieved refractive correction was 3.70 ± 1.70 D, corresponding to 48.1 ± 22.1 ?t? of corneal ablation. No statistically significant difference was found in any measurement in the treated eye compared with the untreated control eye.

CONCLUSIONS: At 6 months postoperatively, photorefractive keratectomy for moderate myopia that resulted in clear corneas did not affect nerve fiber layer thickness measurements, as obtained by optical coherence tomography. [J Refract Surg 2001;17:676-681]
Scraping and Mitomycin C to Treat Haze and Regression After Photorefractive Keratectomy for Myopia
Authors: Vigo Luca , Scandola Elena , Carones Francesco
Published: April 2021

ABSTRACT

PURPOSE: To evaluate the efficacy, safety, and predictability of therapeutic scraping and application of a diluted 0.02% mitomycin C solution to treat haze and regression after photorefractive keratectomy (PRK) for myopia.

METHODS: We performed a non-comparative, non-randomized retrospective study of 35 eyes of 30 patients who had previously undergone PRK for myopia and developed haze and regression after treatment. The range of refractive error after regression was -0.75 to -5.50 D (mean -2.92 D). Haze, ranging from grade 3 to 4 (scale: 0 to 4) caused a best spectacle-corrected visual acuity loss of 1 to 6 Snellen lines. All eyes were treated 6 to 12 months after PRK by scraping the stromal surface and application of a 0.02% mitomycin C solution for 2 minutes using a soaked merocel sponge. No laser ablation was performed. Corneal transparency, refractive error, and visual outcomes were evaluated over a 12-month follow-up period.

RESULTS: All eyes had significant improvement in corneal transparency. Thirty-one eyes had haze grades lower than 1, which were maintained over time. Only four eyes showed haze grades 1 to 2 and two of them needed further treatment using the same technique. At 12 months after treatment, all eyes were within ±1.50 of original intended correction (mean 0.04 ± 0.63 D). BSCVA improved in all eyes. No toxic effects were observed during reepithelialization or during follow-up.

CONCLUSION: Single application of diluted mitomycin C 0.02% solution following scraping of the corneal surface was effective and safe in treating haze and regression after PRK. [J Refract Surg 2003;19:449-454]
Electron Microscopy of Surface Smoothness of Porcine Corneas and Acrylic Plates With Four Brands of Excimer Laser
Authors: Thomas Justus W , Mitra Shrabanee , Chuang Alice Z , Yee Richard W
Published: April 2021

ABSTRACT

PURPOSE: This study compares ablation smoothness patterns produced on four different excimer laser devices available for photorefractive surgery.

METHODS: VISX calibration plastic and porcine cornea were ablated with standard -3.00-D, -6.00-D, and -9.00-D settings using four different excimer lasers: VISX S2 Smooth Scan, Nidek EC-5000, Autonomous Ladar Vision System, and Bausch and Lomb Technolas. Electron microscopy and laser interferometry were used for qualitative evaluation of the ablated surfaces. Corneal ablation surface smoothness was graded by ten independent observers. Calibration plastic ablated surfaces were evaluated quantitatively for smoothness by laser interferometry.

RESULTS: The independent observer assessment of corneal ablation surface smoothness demonstrated that the Autonomous small spot Gaussian profile laser produced the smoothest ablation surfaces, followed by the other broad beam lasers. In comparing ablation smoothness among various refractive powers (-9.00 D, -6.00 D, and -3.00 D), a trend was observed that indicated a correlation of higher refractive settings with decreasing surface smoothness. However, this trend was not statistically significant. The quantitative laser interferometry measurements supported the independent observer ranking of the Autonomous flying small spot ablation profile as the smoothest. However, there were differences between the laser interferometry smoothness rankings and independent observer smoothness rankings.

CONCLUSION: There were significant differences in ablation surface smoothness among the four excimer lasers tested. [J Refract Surg 2003; 19:623-6281
Wavefront-guided Treatment for Previous Laser in situ Keratomileusis and Photorefractive Keratectomy: Case Reports
Authors: Salz James J
Published: April 2021

ABSTRACT

PURPOSE: To describe the off-label use of the Alcon LADARVision System for CustomCornea (LADARWave and LADARVision4000) in two patients, one for retreatment after laser in situ keratomileusis (LASIK) and one for retreatment after photorefractive keratectomy (PRK).

METHODS AND RESULTS: Both patients were unhappy with the quality of their vision after initial refractive surgery. The first patient initially had LASIK to correct -4.75 D of myopia in each eye, and then had retreatment with CustomCornea. Before retreatment, manifest refraction was OD 0.50 -0.50 ? 180° (20/25 uncorrected) and OS -0.50 -0.75 ? 180° (20/40 uncorrected). Two months after retreatment with CustomCornea, his uncorrected visual acuity OD was 20/15, and 1 month after retreatment in his left eye, uncorrected visual acuity was 20/15. The second patient had PRK OD, with a postoperative uncorrected visual acuity of 20/25 and cycloplegic refraction of +1.00 -0.75 x 84°. After CustomCornea retreatment, his 3.5-month postoperative uncorrected visual acuity was 20/15 and manifest refraction was +0.50 -0.50 x 180°.

CONCLUSION: The Alcon LADARVision System for CustomCornea was used effectively to retreat both a myopic LASIK and myopic PRK patient, primarily for subjective quality of night vision complaints. [J Refract Surg 2003;19:S697-S702]
Fluorescein Angiography of Soft Contact Lens Induced Vascularization in Penetrating Keratoplasty
Authors: Mackman Gary , Polack Frank M , Sidrys Linas
Published: April 2021

ABSTRACT

Soft contact lenses after penetrating keratoplasty have become more popularas improved materials with high water content and high oxygen permeability have become available. However, aphakic patients who have undergone penetrating keratoplasty seem to be at high risk for development of graft vascularization when extended wear soft lenses are used for optical correction. This report, to our knowledge, is the first to use corneal fluorescein angiography to study contact lens induced vascularization. Corneal fluorescein angiography, in two cases, showed that vascularization was often more extensive than clinically apparent. Further, these "new" vessels, in both cases, were shown to be "leaky." This great degree of leak contributed to graft edema in both and possibly, in one case, to graft rejection. These findings suggest that care in fitting and careful follow-up is necessary in any graft patient fit with an extended wear lens and that delicate or problem patients may be better aided with other forms of optical correction. Further, this report shows the value of corneal fluorescein angiography as a useful tool in the study of vascularization of the cornea from any cause.