RESUMEN
OBJECTIVE: Most procedures to treat refractive error are based on laser surgery, but other techniques are available. We review the relative advantages and the risk associated with the different surgical options. AREAS OF AGREEMENT: Laser refractive surgery is now a safe and effective alternative to glasses or contact lenses. AREAS OF CONTROVERSY: Because refractive surgery is an area of rapidly developing technology, the relative benefits of the different surgical options remain uncertain. AREAS TO DEVELOP RESEARCH: Controlled trials are needed to provide better guidance as to the relative merits of the different surgical options. Better interventions are required to minimize the biological response after laser surface treatment to eliminate the need for mechanical cutting of a flap for laser in situ keratomileusis. An effective surgical treatment for presbyopia is awaited.
Asunto(s)
Cirugía Laser de Córnea/métodos , Terapia por Láser/métodos , Errores de Refracción/terapia , Procedimientos Quirúrgicos Refractivos/métodos , Cirugía Laser de Córnea/efectos adversos , Humanos , Satisfacción del Paciente , Errores de Refracción/diagnósticoRESUMEN
PURPOSE: To evaluate the clinical results of epi-LASIK for the treatment of low to moderate myopia and myopic astigmatism. DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: Two hundred thirty-four eyes of 138 patients underwent epi-LASIK for the correction of low to moderate myopia. Mean preoperative spherical equivalent ranged from -1.0 to -7.25 diopters (D) (-3.74+/-1.46, mean+/-standard deviation [SD]) and baseline logarithm of the minimum angle of resolution (logMAR) best spectacle-corrected visual acuity (BSCVA) from 0.10 to -0.18 (mean+/-SD, 0.00+/-0.06). METHODS: All enrolled eyes underwent epi-LASIK using the Centurion SES epikeratome (Norwood Abbey EyeCare, Victoria, Australia) and the Allegretto (Wavelight Laser Technologie AG, Erlangen, Germany) laser platform. The enrolled patients were followed up daily until the epithelial healing was complete as well as at the 1-, 3-, 6-, and 12-month postoperative intervals. MAIN OUTCOME MEASURES: The main parameters assessed were subjective evaluation of postoperative pain, uncorrected visual acuity (UCVA) and BSCVA, manifest refraction, haze grade, and contrast sensitivity of the operated eyes. RESULTS: The mean epithelial healing time was 4.70+/-0.87 days (range, 3-7 days), with mean logMAR UCVA on the day of reepithelization of 0.26+/-0.14 (range, 0.7-0.0). One year after the treatment, the spherical equivalent of the treated eyes (n = 222) ranged from -1.25 to +0.625 D (mean+/-SD, -0.18+/-0.6 D), with 80.33% of the eyes within 0.5 D (96.72% within 1 D) of the attempted correction. At the same interval, 86% of the eyes had clear corneas and 14% clinically insignificant (trace) haze, whereas 60% of the eyes had a line gain of 1 or more lines of BSCVA. Mean logMAR contrast sensitivity of the treated eyes at 4 different spatial frequencies was improved or remained unchanged throughout the follow-up period. CONCLUSIONS: One-year visual and refractive results after epi-LASIK suggest that it is a safe and efficient method for the correction of low to moderate myopia and myopic astigmatism.
Asunto(s)
Astigmatismo/cirugía , Queratomileusis por Láser In Situ/métodos , Miopía/cirugía , Adolescente , Adulto , Astigmatismo/fisiopatología , Sensibilidad de Contraste/fisiología , Epitelio Corneal/fisiología , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Miopía/fisiopatología , Dimensión del Dolor , Dolor Postoperatorio/fisiopatología , Refracción Ocular/fisiología , Estudios Retrospectivos , Factores de Riesgo , Resultado del Tratamiento , Agudeza Visual/fisiología , Cicatrización de Heridas/fisiologíaRESUMEN
PURPOSE: To compare the effect of Epi-LASIK or Laser In Situ Keratomileusis (LASIK) on corneal sensitivity and tear function. DESIGN: Prospective, non-randomized comparative clinical trial. METHODS: Seventy-nine eyes (Group A) underwent Epi-LASIK and 61 eyes underwent LASIK (Group B) for the treatment of myopia. Matching parameters between the groups were age and attempted correction. Corneal sensitivity, tear break-up time (BUT), and Schirmer test II were evaluated before and at one, three, and six months after the procedure. RESULTS: Corneal sensitivity and BUT were decreased at one month in Group A (P < .001) to be restored by the third month (P = .71 and P = .58, respectively). In Group B, corneal sensitivity and BUT were reduced postoperatively (P < .001). There was a significant difference in corneal sensitivity between the two groups at all postoperative intervals. Schirmer test II was not significantly decreased postoperatively in Group A. In Group B, it was decreased at one and three months and restored by the sixth month. CONCLUSION: Epi-LASIK-treated eyes had faster rehabilitation of corneal sensitivity and tear function than LASIK-treated eyes.
Asunto(s)
Córnea/fisiología , Queratomileusis por Láser In Situ , Miopía/cirugía , Lágrimas/fisiología , Humanos , Miopía/fisiopatología , Estudios Prospectivos , Recuperación de la Función/fisiología , Sensación/fisiologíaRESUMEN
PURPOSE OF REVIEW: The aim of this article is to provide an update on epipolis laser in-situ keratomileusis--an alternative surface photorefractive surgical technique for the correction of myopia. RECENT FINDINGS: In-vivo studies on animal models provide evidence that the replacement of the epithelial sheet on an ablated cornea can control corneal wound healing. Preliminary clinical data confirm that epipolis laser in-situ keratomileusis can provide excellent long-term visual and refractive results. The problems of late visual rehabilitation and postoperative pain, however, have not yet been fully addressed. SUMMARY: Being a recently introduced surgical photorefractive technique for ametropias correction, epipolis laser in-situ keratomileusis is a fast evolving area of interest for refractive surgeons.
Asunto(s)
Epitelio Corneal/cirugía , Queratomileusis por Láser In Situ/métodos , Miopía/cirugía , Humanos , Resultado del Tratamiento , Cicatrización de HeridasRESUMEN
PURPOSE: To report the histological findings of four eyes of three patients who underwent epi-LASIK treatment for the correction of low myopia. METHODS: The epithelial sheets were harvested either immediately after separation (one eye) or were accidentally dislocated and harvested from the operative eyes 24 hours after treatment (three eyes). All sheets underwent optical and transmission electron microscopy. RESULTS: Histological evaluation showed that the majority of the epithelial cells were morphologically normal in all examined specimens. CONCLUSIONS: Histological examination of specimens in four eyes showed that 24 hours after mechanical separation the epithelial cells' morphology was close to normal.
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Epitelio Corneal , Queratomileusis por Láser In Situ/métodos , Miopía/cirugía , Epitelio Corneal/cirugía , Epitelio Corneal/ultraestructura , Estudios de Seguimiento , Humanos , Técnicas In Vitro , Microscopía Electrónica de Transmisión , Miopía/patología , Periodo PosoperatorioRESUMEN
PURPOSE: To report the intraoperative management of incomplete microkeratome LASIK flaps. DESIGN: Small, retrospective, noncomparative, interventional case series. PARTICIPANTS: Five outpatients. METHODS: In 5 eyes of 5 patients, the premature stop of the microkeratome resulting from mechanical obstacles resulted in an incomplete flap that would not allow for the completion of the LASIK procedure. After the careful realignment of the partial flaps and the removal of the identified obstacles, the second pass of the microkeratome resulted in flaps of the intended size. MAIN OUTCOME MEASURES: Final creation of a flap as intended, completion of the procedure, and visual and refractive outcome of the operative eyes. RESULTS: The second pass of the microkeratome resulted in flaps as planned. All the procedures were completed, and the operative eyes that were followed up for at least 3 months had excellent visual and refractive results. CONCLUSIONS: The second pass of the microkeratome can successfully manage incomplete flaps resulting from microkeratome premature stop as a result of mechanical obstacles.
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Sustancia Propia/cirugía , Complicaciones Intraoperatorias , Queratomileusis por Láser In Situ/métodos , Procedimientos Quirúrgicos Refractivos , Colgajos Quirúrgicos , Adulto , Sustancia Propia/patología , Femenino , Humanos , Cuidados Intraoperatorios , Queratomileusis por Láser In Situ/efectos adversos , Masculino , Persona de Mediana Edad , Refracción Ocular , Errores de Refracción/etiología , Reoperación , Estudios Retrospectivos , Agudeza VisualRESUMEN
PURPOSE: To evaluate the clinical results of epi-LASIK, a new surface ablation surgical technique for the treatment of low myopia. SETTING: Vardinoyannion Eye Institute of Crete, University of Crete, Greece. METHODS: Forty-four eyes of 31 patients had epi-LASIK for the correction of low myopia. Mean preoperative spherical equivalent was 3.71 diopters (D) +/- 1.2 (SD) (range -1.75 to -7.00 D) and the mean baseline logMAR best spectacle-corrected visual acuity was -0.01 +/- 0.06 (range 0.10 to -0.10). All the epithelial separations were performed with the Centurion epikeratome (CIBA Surgical). The enrolled patients were followed daily until the epithelial healing was complete as well as at 1- and 3-month intervals. On the operative day, patients filled out a questionnaire grading visual performance and pain score of treated eyes every 2 hours for a total of 5 records. RESULTS: The mean epithelial healing time was 4.86 +/- 0.56 days (range 3 to 5 days). The mean logMAR uncorrected visual acuity on the day of reepithelization was 0.19 +/- 0.09 (range 0.40 to 0.10). At 1 month, the mean was spherical equivalent of the treated eyes (N=44), -0.3 +/- 0.6 D (range -1.0 to 0.87 D), and at 3 months it was (N=37), -0.10 +/- 0.4 D (range -0.75 to 0.75 D); 97% of eyes had clear corneas or trace haze 3 months after treatment. CONCLUSIONS: Preliminary clinical results suggest that epi-LASIK is a safe and efficient method for the correction of low myopia. Further studies will establish this method as an alternative surface ablation procedure.
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Astigmatismo/cirugía , Epitelio Corneal/cirugía , Queratomileusis por Láser In Situ/métodos , Miopía/cirugía , Adolescente , Adulto , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Complicaciones Posoperatorias , Pronóstico , Refracción Ocular , Agudeza Visual , Cicatrización de HeridasRESUMEN
To compare the effect of mechanical and alcohol-assisted excision on the histological ultrastructure of epithelial disks from human corneas. Vardinoyiannion Eye Institute of Crete, University of Crete, Medical School, Crete, Greece. Ten eyes of 10 patients were deepithelialized by 1 of 2 two techniques. In 6 eyes, a customized instrument was used to mechanically separate the epithelial layer. In 4 eyes, the epithelial disks were obtained using the conventional laser-assisted subepithelial keratectomy (LASEK) technique; that is, with alcohol concentrations of 15% and 20%. All specimens were assessed by light and electron microscopy, and the histological findings of the 2 methods were compared. Transmission electron microscopy showed that when the epithelial disks were excised by mechanical separation, the lamina densa and lamina lucida were preserved and the hemidesmosomes had normal morphology along almost the entire length of the basement membrane. The basal epithelial cells of the separated epithelial disks showed minimal trauma and edema. Specimens obtained using 15% and 20% alcohol concentrations showed formation of cytoplasmic fragments of the basal epithelial cells, enlargement of the intercellular spaces, and extensive discontinuities in the basement membrane, which was excised at the level of the lamina lucida. Mechanical separation did not affect the normal cell morphology of the excised epithelial disks. Transmission electron microscopy of the specimens proved the manual technique is less invasive to epithelial integrity than LASEK using either alcohol concentration.
Asunto(s)
Separación Celular/métodos , Córnea/ultraestructura , Desbridamiento/métodos , Células Epiteliales/ultraestructura , Etanol/farmacología , Queratomileusis por Láser In Situ/métodos , Membrana Basal/efectos de los fármacos , Membrana Basal/cirugía , Humanos , Colgajos QuirúrgicosRESUMEN
PURPOSE: The aim of the current study was to control the hypothetical effects of decreased laser energy delivered to the peripheral cornea during phototherapeutic keratectomy (PTK) and provide quantitative calculation of induced low and high order aberrations. METHODS: We employed a model eye to simulate the refractive effect of homogeneous laser corneal irradiation, as in PTK, for different laser fluences (range 125 to 225 mJ/cm2) and treatment depths up to 200 microm. RESULTS: The hyperopic shift induced by the relatively lower energy delivered at the peripheral ablation zone during PTK was proportional to the treatment depth and inversely proportional to the energy fluence. The hyperopic shift calculated using the above ablation parameters was lower compared to previously reported clinical results. Higher order wavefront aberration (total root mean square) changes were of minimal significance for treatment depths up to 200 microm. CONCLUSIONS: After PTK, a hyperopic shift cannot be attributed to the energy delivery method alone. Modification of laser energy delivery algorithms may only minimize PTK-induced hyperopia.
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Córnea/cirugía , Opacidad de la Córnea/cirugía , Hiperopía/etiología , Queratectomía Fotorrefractiva/efectos adversos , Complicaciones Posoperatorias , Humanos , Hiperopía/prevención & control , Láseres de Excímeros , Matemática , Modelos Biológicos , Queratectomía Fotorrefractiva/métodosRESUMEN
The reports of an increasing incidence of iatrogenic ectasia, the evolution of wavefront aberrometry, and the suggestion that the laser in situ keratomileusis flap could lead to unpredictable biomechanical corneal changes have renewed interest in surface ablation and have set the stage for the introduction of alternative photorefractive treatment modalities. The theoretical advantage of surface procedures, such as laser epithelial keratomileusis that preserve the epithelial button, stems from the repositioning of the epithelial flap over the laser-ablated corneal surface. This epithelial sheet is thought to act as a natural contact lens that decreases postoperative pain and haze formation. Epipolis laser in situ keratomileusis is an alternative modality of epithelial separation with the use of a device that features a blunt oscillating blade. This surgical approach does not require the use of alcohol for epithelial loosening.
Asunto(s)
Queratomileusis por Láser In Situ/métodos , Procedimientos Quirúrgicos Refractivos , Córnea/citología , Córnea/cirugía , Células Epiteliales , HumanosRESUMEN
BACKGROUND: To compare the corneal healing response between conventional and phototherapeutic keratectomy through a masking agent, in rabbit corneas. METHODS: 24 adult rabbits underwent phototherapeutic keratectomy. Animals were divided in two groups: 12 received photoablation through a masking agent (PALM gel) and the remaining 12 received conventional phototherapeutic keratectomy of equal depth and served as control. Light and transmission electron microscopy was performed in specimens of both groups obtained: immediately after, four hours, one week, one, three and six months after treatment. RESULTS: Reepitheliazation was complete within five days in all eyes. Light and transmission electron microscopy did not reveal any differences of the healing process in the experimental eyes compared to the controls. CONCLUSION: Photoablation through the PALM technique did not result any evident alterations of the reepithelisation and stromal healing process.
Asunto(s)
Carragenina/uso terapéutico , Colágeno Tipo I/uso terapéutico , Sustancia Propia/patología , Epitelio Corneal/patología , Queratectomía Fotorrefractiva/métodos , Cicatrización de Heridas/efectos de los fármacos , Animales , Córnea/efectos de los fármacos , Córnea/cirugía , Quimioterapia Combinada , Geles , Láseres de Excímeros , ConejosRESUMEN
OBJECTIVE: To identify the incidence and refractive outcome of intraoperative laser in situ keratomileusis (LASIK) complications using one type of microkeratome. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Three hundred thirty-four consecutive myopic LASIK patients (September 1997 to November 1998) operated on by one surgeon. INTERVENTION: Myopic LASIK surgeries were performed with the Mediate Mel 60 Aesculap Meditec Laser system. MAIN OUTCOME MEASURES: Preoperative and 1-year postoperative spherical equivalent, best spectacle-corrected visual acuity (BSVA), and corneal anatomic features (as obtained from videokeratography) were recorded, as was the incidence of intraoperative complications. RESULTS: Forty-eight (14%) eyes had keratome-related complications. Thirty-seven (77%) eyes were immediately treated; the remaining eyes were treated on a later date. One year after treatment, 13% of the immediately treated complicated eyes maintained the preoperative BSVA; 24% had a 1-line loss; 2.7% had a greater loss of BSVA. CONCLUSIONS: Microkeratome-related complications may result in loss of BSVA. The complication of an irregular flap had the poorest refractive outcome in this series of eyes. We did not find any statistically significant relationship between corneal anatomic factors and keratome-related complications in this series.