Posters

Transmittance and histology of the layers of the chicken cornea: an animal model to study corneal conditions in humans

Poster Details

First Author: M.Penadés Fons SPAIN

Co Author(s):    C. Peris Martinez   J. Artigas Verde   M. Garcia Domene   D. Martinez Martinez           

Abstract Details

Purpose:

The aim of this study was to compare chicken and human corneas in transmittance and histology in order to evaluate this species as a good animal model to study corneal conditions. Therefore, two objectives were established: 1) To determine the spectral transmission of the layers of the chicken cornea, as well as its total transmission between 250 and 1000 nm (Ultraviolet A, Ultraviolet B, part of Ultraviolet C, visible spectrum and infrared A). 2) To observe, describe and measure histologically the thickness of all layers from the chicken cornea and compare them with the ones described in humans.

Setting:

The study was developed in FISABIO Oftalmología Médica. Valencia (Spain).

Methods:

Fifteen corneas were obtained from homogeneous 42 days-old, White Leghorn chicken (Gallus gallus domesticus). In the experimental operating room, selected layers from the corneas were scrapped off with a surgical blade, or detached individually. The transmittance of the corneas was measured by placing them between two sapphire sheets (diameter: 7.5mm; thickness: 0.4mm), used in the spectrophotometer Perkin-Elmer Lambda 35UV/VIS. Then, all corneas were fixed in 4% formaline, sliced and routinary stained with Hematoxylin-Eosin to be examined under the microscope. The programme ImageJ was used to measure the thickness of each leayer. The absorption coefficient was determined applying the Beer-Lambert law.

Results:

Regarding the chicken cornea, five layers were observed histologically. An average thickness of the epithelium was 32.36 μm (7.41% of entire cornea thickness), Bowman's membrane 4.33 μm (0.99%), stroma 392.98 μm (90,01%), Descemet's membrane 2.83 μm (0,65%), endothelium 4.05 μm (0,93%), entire 436.55 μm. Altogether, the celular composition and the proportinal thickness of the different layers are comparable to those of the human cornea. On the other hand, the curve of the spectral transmittance of the entire chicken cornea, and of each of its layers, was also similar in morphology to the one described for the human cornea.

Conclusions:

The similarity observed between the anatomy and the transmittance of the layers of the chicken cornea in comparison with the human cornea, suggests that the the chicken cornea is a good candidate to be validated as an animal model for corneal conditions. However, further studies must be performed to confirm these results. So far, these data reveal the importance of the strcutural elements of the cornea and are of great interest regarding the approach of refractive surgery (LASEK, LASIK, PRK), in which some layers are modified and, therefore, the protection of the eye against ultraviolet radiation can be affected.

Financial Disclosure:

None