Setsuko S. Oak

Ocular Blood Flow Velocity in Age-related Macular Degeneration

BACKGROUND Changes in the structure of the ocular blood vessels associated with age-related macular degeneration (AMD) have been described in some detail, but comparatively little is known of the concomitant circulatory changes. The goal of this study is to evaluate changes in the ocular circulation that may be associated with AMD. METHODS Ocular blood flow velocities and vessel pulsatilities were measured in volunteers with and without AMD using a color Doppler imaging unit. Spectral analyses were recorded from the ophthalmic artery, central retinal artery and vein, the temporal and nasal short posterior ciliary arteries, and the four vortex veins. RESULTS Adjusting for age, pulsatility indices of all arteries were higher in subjects with AMD (central retinal artery [P = 0.02]; temporal and nasal short posterior ciliary arteries [P = 0.06 and 0.002, respectively]; and ophthalmic artery [P = 0.24]). End-diastolic blood flow velocity of the short posterior ciliary arteries tended to decrease in the presence of AMD. CONCLUSIONS The combination of increased pulsatility and decreased velocity of the short posterior ciliary arteries, observed in the presence of AMD, are interpreted as evidence of increased vascular resistance. The clinical signs of AMD may be related to degradation of the metabolic transport function of the retinal pigment epithelium, resulting from impaired choroidal perfusion.

Evidence for Mitosis in the Adult Corneal Endothelium

Intracellular structures probably representative of mitotic figures were seen by specular microscopy in the endothelium of a corneal graft following a rejection reaction. Serial measurements over an eight month period initially showed grossly enlarged cells and apparent mitotic figures. Subsequently, clusters of cells smaller than any cells previously seen were observed. Measurements of endothelial cell area over this period demonstrated a highly significant (P less than 0.0001) decrease in cell area, or increase in cell density, with time. These observations indicate that at least under some circumstances mitosis occurs in the endothelium of the adult human cornea.

Morphometric analysis of corneal endothelium following radial keratotomy

ABSTRACT We performed morphoinetric analysis of the central corneal enclothelium on 24 eyes of 19 patients who had had anterior radial keratotomy. The endothelium was analyzed for a variety of parameters, including cell area, perimeter, side lengths, cell shape, and number of sides. Mean, standard deviation, and coefficient of variation were calculated for each parameter. The mean cell density decreased from 2,8:35 to 2,677 cells/mm2, mean cell perimeter increased from 71.4 &mgr;m to 74.3 &mgr;m, and mean side length increased from 11.8 &mgr;m to 12.3 &mgr;m following surgery. The changes in these three parameters were statistically significant (P < 0.05). The coefficient of variation of cell area (polymegathism) changed from 0.319 to 0.307, the hexagonality changed from 62.5% to 59.6%, and the cell shape changed from 0.872 to 0.867. The changes in these parameters were not statistically different before and after surgery. The group of patients that had no reported microperforations shoNved only a small decrease of cell density (1.6%), while the group of patients that had microperforations showed a large decrease of cell density (14.3%). The cell perimeter and side lengths showed a similar pattern. The group of corneas with the optical zone diameter less than 3.5 nun showed a decrease in mean cell density from 2,994 to 2,725 cells/mm2, and the cell shape changed from 0.874 to 0.866 following surgery. The changes in these parameters were statistically significant (P < 0.05) before and after surgery. Among all factors associated with radial keratotomy, microperforation and a small diameter of central optical zone appear to be the two greatest risk factors.

Clinical Examination of the Crystalline Lens by Retrocorneal Specular Microscopy

Normal crystalline lenses and a variety of primary and secondary cataracts were photographed with a contact clinical specular microscope having a new W10X long working distance objective. In the normal lens, the anterior and posterior cell pattern and the lens fiber pattern could be seen. In patients with developing cataracts, a variety of abnormal structures was observed; in some cases the detailed morphologic structure of the light scattering objects could be appreciated. In pseudophakic patients, precipitates, leukocytes, and debris were observed on the surface of IOL implants. The methods described enable cellular and morphologic changes occurring with time in the lens and capsule to be studied. The results obtained show the potential usefulness of specular microscopy for evaluation and documentation of retrocorneal pathologic structures at high magnification.