Direct objective quantification of corneal haze after excimer laser photorefractive keratectomy for high myopia.
Ophthalmology
; 103(11): 1970-8, 1996 Nov.
Article
em En
| MEDLINE
| ID: mdl-8942897
ABSTRACT
PURPOSE:
The purpose of the study is to measure regional distribution differences in corneal haze after excimer laser photorefractive keratectomy for high myopia.METHODS:
The authors developed computerized gradient edge detectors with which were analyzed digitized anterior slit-lamp photographs of 40 eyes, an average of 21.0 plus or minus 14.5 weeks after photorefractive keratectomy for high myopia (-6 to -22 diopters). A treated area an adjacent untreated area on the anterior corneal surface, each containing six regions, were quantified, and the difference was correlated with various parameters.RESULTS:
Mean differences between scarred and clear areas for haze grade 0.5, 1.0, 2.0, 3.0, and 4.0 were 16.9, 26.6, 42.6, 60.4, and 76.4 gray levels, respectively (rs = 0.96; P = 0.0001). A low but statistically significant correlation between the intended correction and postoperative corneal haze was found (r = 0.33; P = 0.037). The mean coefficient of variation of the amount of opacification within each treated area was 9.4%. This coefficient of variation increased with a longer follow-up time (r = 0.88; P = 0.0001). The difference in the intensity of haze between the center and more peripheral regions over the entrance pupil did not correlate with the attempted correction. However, a strong association between a relatively less severe central corneal haze with respect to more peripheral haze and longer follow-up time was found (r = -0.96; P = 0.0001).CONCLUSION:
The amount of corneal haze showed a weak positive association with the attempted correction in excimer laser photorefractive keratectomy for high myopia. Corneal haze appeared fairly uniformly distributed within the ablation zone, but a more heterogeneous distribution was found with a longer follow-up time. Furthermore, later postoperative examinations disclosed a clear trend toward diminishing central opacification relative to peripheral regions over the entrance pupil.
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Base de dados:
MEDLINE
Assunto principal:
Processamento de Imagem Assistida por Computador
/
Ceratectomia Fotorrefrativa
/
Córnea
/
Opacidade da Córnea
/
Miopia
Tipo de estudo:
Etiology_studies
/
Observational_studies
/
Prognostic_studies
/
Risk_factors_studies
Limite:
Adult
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Revista:
Ophthalmology
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Espanha