RESUMEN
BACKGROUND: In contrast to incisional keratotomy, corneas that have undergone photorefractive keratectomy may be difficult to detect by inspection with slitlamp biomicroscopy alone. Eye bank corneas that have undergone high myopic refractive surgical correction could potentially result in substantial postoperative hyperopic correction if used as donor tissue for corneal transplantation. Surface irregularities or displacement of the treated optical zone within the graft in relation to the entrance pupil of the recipient could result in significant induced astigmatism and distortion. This study examines computerized videokeratographic screening of eye bank globes as a strategy for detecting myopic photorefractive keratectomy. METHODS: Preoperative and postoperative corneal topographic maps of freshly enucleated human and rabbit eyes that have undergone myopic photorefractive keratectomy with an excimer laser were placed in a globe-fixating device and analyzed using a vertically oriented videokeratoscope. The same system was applied in an actual eye bank setting, and potentially transplantable globes from donors without a history of corneal surgery were analyzed. RESULTS: Computerized videokeratography using a vertically mounted system reliably detected photorefractive keratectomy in 12 of 12 human eye bank corneas treated by excimer photorefractive keratectomy in a range between -1.5 to -6.0 diopters. This method also detected similar changes on lased rabbit corneas enucleated 6 weeks after excimer surgery. Data processed with the tangential mode yielded a "bull's-eye" topography pattern reflecting central corneal flattening that was more sensitive in detecting myopic corrections than the conventional axial formula-based color maps. False-positive results were not detected in 96 cadaver globes sequentially screened in the eye bank. CONCLUSIONS: Computerized videokeratography represents a feasible method to screen donor globes for myopic photorefractive keratectomy as shown by the in vitro and rabbit models. However, only whole globes and not corneoscleral sections are amenable to processing with this technique. Tangential maps provided greater sensitivity in detecting low myopic corrections than the axial formula-based color maps.
Asunto(s)
Córnea/patología , Topografía de la Córnea/métodos , Bancos de Ojos , Miopía/diagnóstico , Queratectomía Fotorrefractiva , Animales , Córnea/cirugía , Trasplante de Córnea , Humanos , Hiperopía/prevención & control , Láseres de Excímeros , Miopía/cirugía , Complicaciones Posoperatorias/prevención & control , Conejos , Donantes de TejidosRESUMEN
PURPOSE: To test the ProTek (Vifilcon A) therapeutic soft contact lens in the alleviation of post-photorefractive keratectomy pain, its effect on epithelial healing, and its safety. METHODS: Forty-seven consecutive eligible patients undergoing unilateral excimer laser photorefractive keratectomy for myopia were randomly assigned to receive standard postoperative care with or without the use of a ProTek soft contact lens. Patients prospectively graded a self-administered 5-point scale for pain and a 4-point scale for abnormal sensations at 4, 8, 12, 16, and 20 hours after surgery. They also recorded the type and dose of all medications taken during that time period. All patients were examined on the first and third days after surgery. The lenses were worn continuously for 3 days. RESULTS: The soft contact lens group (n = 24) disclosed a statistically significant (P < .05) reduction in pain intensity and abnormal sensations that was greatest at 8, 12, 16, and 20 hours postoperatively. Compared with control patients (n = 23), the soft contact lens group showed significant decreased dependence on most pain medications after the 12th hour (P < .05) and faster epithelial healing (P = .03). However, one case of bacterial keratitis, two cases of subepithelial infiltrates, and seven cases of contact lens intolerance were present in the soft contact lens group. CONCLUSIONS: The ProTek therapeutic soft contact lenses were effective in decreasing pain and other related abnormal sensations after excimer photorefractive keratectomy. They decreased dependence on pain medications and hastened epithelial healing but were not well tolerated in some patients.
Asunto(s)
Lentes de Contacto Hidrofílicos , Córnea/cirugía , Miopía/cirugía , Dolor Postoperatorio/terapia , Queratectomía Fotorrefractiva/efectos adversos , Adulto , Analgésicos/administración & dosificación , Lentes de Contacto Hidrofílicos/efectos adversos , Femenino , Humanos , Láseres de Excímeros , Masculino , Persona de Mediana Edad , Dimensión del Dolor , Dolor Postoperatorio/etiología , Estudios Prospectivos , Seguridad , Encuestas y Cuestionarios , Cicatrización de HeridasRESUMEN
PURPOSE: To present two cases of excimer photorefractive keratectomy decentration associated with visual distortion secondary to irregular astigmatism. METHOD: Patients were retreated with a repeat photorefractive keratectomy using a technique whereby the circle of adherent epithelium overlying the decentered ablation served as a mask. RESULTS: After retreatment, there was significant improvement in the patients' visual symptoms, decreased astigmatism on refraction, and better centration on corneal topography. CONCLUSION: This method appears to offer an effective means to treat photorefractive keratectomy ablation zone decentration by improving the abnormalities introduced by the initial decentration.