Quantitative assessment of anteroposterior keratocyte density in the normal rabbit cornea.
ABSTRACT The anteroposterior keratocyte density distribution in the rabbit cornea was measured. Unsectioned tissue blocks from the central cornea of five rabbits were stained with propidium iodide and imaged using a Leica laser scanning confocal microscope. A z-series of images was acquired confocal microscope. A z-series of images was acquired in each sample, from anterior to posterior stroma in either 3- or 8-microns steps. Software was developed to allow interactive marking of the keratocyte nuclei within each section of the z-series and for calculating cell density. For convenience, cell density was expressed as the number of cells per corneal volume element (CVE), where CVE is a newly defined volume unit with x, y, and z dimensions of 250, 250, and 10 microns, respectively. The calculated keratocyte density was 20.2 +/- 1.0 cells/CVE (n = 5), which is equivalent to 32,360 +/- 1,660 cells/mm3. The greatest density was underneath the epithelium (26.3 +/- 2.5 cells/CVE), the density then decreased linearly with depth to 15.2 +/- 1.4 cells/CVE; there was a slight increase in density pre-Descemets membrane to 18.5 +/- 3.5 cells/CVE. A 30% decrease in cell density over the entire anteroposterior stromal thickness was observed. To facilitate statistical analysis, the cell density was averaged over 5% thickness intervals from anterior to posterior cornea. A significant difference in mean cell density of these intervals was found (ANOVA, n = 20, p < 0.01). To further assess the density distribution, linear regression analysis was performed. A significant correlation was found between keratocyte density and stromal depth (R = -0.94, n = 20, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
[Show abstract] [Hide abstract]
ABSTRACT: Purpose: To document keratocyte distribution and changes with age in the cellular network of the human cornea in vivo.Setting: Department of Ophthalmology, University of Rostock, Rostock, Germany.Methods: Forty-nine eyes of 31 healthy subjects of various ages were examined with a modified Microphthal® scanning-slit confocal microscope (SSCM) (Hund) to document keratocyte distribution in the intact living cornea. Optical sections made by confocal microscopy were recorded on videotape, and the keratocyte density was determined for the total volume of the cornea and for the stromal sublayers.Results: The highest cell density was in the anterior stroma of the cornea immediately posterior to Bowman’s membrane (24 320 cells/mm3 ± 6740 [SD]), the lowest in the central area (11 610 ± 4290 cells/mm3), and an intermediate density in the posterior stroma immediately adjacent to Descemet’s membrane (18 850 ± 4610 cells/mm3). The differences were statistically significant (P < .005). The keratocyte density was significantly lower in the anterior and posterior regions in the group older than 50 years: Cell density at 4% depth was 20 960 ± 8200 cells/mm3 and at 96%, 15 520 ± 4290 cells/mm3 (P < .05).Conclusions: In healthy living corneas, the keratocyte density was high in the areas adjacent to Bowman’s and Descemet’s membranes and was lower in patients older than 50 years than in those younger than 50 years. Further studies are needed to document the rate of change with age and to better understand the role and capacity of aging keratocytes in regenerative processes following corneal diseases or surgical procedures.
Progress in Retinal and Eye Research 01/1995; 14(2):527-565. DOI:10.1016/1350-9462(94)00018-B · 9.90 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: In recent years, confocal microscopy has become a powerful tool for examining microscopic structures in the living eye. The decisive advantage of this technique is that it permits the investigation of optical sections of relatively thick (> 10 mu m) specimens. Because confocal microscopy suppresses the out-of-focus blur, sharp three-dimensional images with excellent resolution can be obtained. Confocal microscopy is therefore able to provide more information than the classic methods -i.e., specular microscopy and slit-lamp biomicroscopy. This paper reviews recent applications of confocal microscopy in three fields of ophthalmology: the observation of the anatomy of the anterior parts of the eye, the investigation of these structures after local administration of drugs and, finally, the use of this technique for the diagnosis of infectious ocular diseases.Journal of Ocular Pharmacology and Therapeutics 12/1997; 13(6):559-578. DOI:10.1089/jop.1997.13.559 · 1.42 Impact Factor