Electron microscopic studies of epithelial adhesion complex of keratoconus

PURPOSE: Keratoconus is a bilateral noninflammatory ecstatic disease of cornea. Clinical manifestations and treatments are well-described , but the exact pathophysiology has many debates. There are many reports on pathologic abnormalities of keratoconus, but few reports on epithelial adhesion complex. The authors investigated the abnormalities in epithelial adhesion complex of keratoconus. METHODS: Using 4 corneas from 4 recipients of penetrating keratoplasty, examination was done with transmission electron microscope (Hitachi-600, Japan) after proper fixation and staining. Central and peripheral portion of each corneal tissues were examined. RESULTS: In two tissues, severe degeneration of basement membrane and Bowman's layer were found. Some degree of abnormalities was found in other tissues, which had minimal change. Some of hemidesmosomes, the most distinct part of adhesion complex, were found only in well-maintained tissue but the distribution was abnormal. CONCLUSIONS: The fact that basal plasma membrane had selectively more degenerations and changes than intercellular plasma membrane implies pathophysiology of keratoconus on adhesion complex, basal plasma membrane, basement membrane and Bowman's layer. Further study on this issue will reveal more information as to its pathophysiology.

Analysis of 137 Pediatric Low Vision Patients

PURPOSE: We intended to analyze the characteristics of a pediatric low vision population. METHODS: Among 430 patients who visited our low vision clinic from May 1995 to April 2000, 137 patients(31.9%) aged 15 years or less were reviewed to study epidemiologic characteristics, prescribed aids and required magnification. RESULTS: The percentage of pediatric low vision patients was higher than that of developed countries. Male predominance was found. Optic atrophy(41.6%), congenital cataract(12.4%), macular degeneration and dystrophy(9.5%) were the major causes of low vision in this population. The most commonly prescribed low vision aid was a telescope. For near task, light-gathering magnifiers were prescribed most commonly. The visual acuity was improved significantly at near and far distance after correction with low vision aid. The mean required magnification was 3.5 xand this means that a low magnification was sufficient in the majority of cases. CONCLUSIONS: Early rehabilitation and long-range planning for the low vision child are required because of profound effect of childhood visual impairment.