Confocal microscopic study of rabbit and human corneal epithelia using two objectives with different numerical aperture

Abstract

The prospective study compares the confocal microscopic images of the rabbit and human corneal epithelial layers obtained with two objectives having different numerical apertures (NA). Methods: Ten rabbit eyes were enucleated and kept in place by a pneumatic support to ensure the best performance of each objective, with no disturbance due to eye movements. Five normal patients were selected after agreement. The rabbit eyes and those of the patients were all examined with slit lamp. Confocal microscopy (Tomey, Erlangen-Tennenlohe, Germany) was performed with Achroplan (Zeiss, Oberkochen, Germany) 40x/NA = 0.75 and 63x/NA = 0.9 objectives. Selected images of the corneal epithelium layers were evaluated qualitatively for the size, shape, light scattering, and reflection of the cells. Results: The cells in the superficial corneal epithelium of rabbit and human eyes, before desquamation, produced a much brighter reflection than the surrounding cells. This was clearly seen only with the 63x/NA = 0.9 objective. The corneal epithelium subsegments of the rabbit eyes, like the basal cell layer or the intermediate cell layer (wing cells), were visible under the high numerical aperture (63x/NA = 0.9) objective only. These layers, in the human eyes, were more clearly visible using the high numerical aperture objective. Conclusion: An objective with a high numerical aperture and a high optical resolution provided an improved analysis to study all the layers of the rabbit and human corneal epithelium. Estudo em microscopia confocal do epitélio corneano do coelho e do homem utilizando objetivas com diferentes aberturas numéricas Trabalho realizado no Serviço de Oftalmologia do Hospital Hôtel-Dieu de Paris e apresentado em parte nos seguintes congressos: ICER-XIII International Congress of Eye Research, Paris, França, Julho de 1998; DOG-Deutsche Ophthalmologische Gesellschaft, Berlin, Alemanha, Setembro de 1998. Os autores declaram não possuir nenhum interesse financeiro em produtos, equipamentos ou medicamentos mencionados no estudo.

In‐vivo estimation of tissue electrical conductivities of a rabbit eye for precise simulation of electric field distributions during ocular iontophoresis

“…The difference of the electrical conductivity between the human eye and the rabbit eye originates from the difference of the tissue properties. Compared to the human, the rabbit has less layers in the superficial tissues, such as the cornea and sclera, 33 which lead to the higher conductivity of the sclera in the rabbit than in the human. In addition, the electrical conductivities of living tissues are considerably different from those of dead tissues.…”