The major cause of corneal opacity and resultant visual loss is a critical decrease in corneal endothelial cell density. Due to the fact that corneal endothelial cells do not generally proliferate, cell densities gradually decrease in the corneal endothelium with age. Before we can begin to aid patients with decreasing endothelial cell densities, by inhibiting cell death or stimulating cell proliferation, it is necessary to understand the basic cell signalling that underlies these processes. As human tissue is difficult to obtain, a representative animal model of corneal endothelium was devised. Analysis of cell morphology and expression of ct1 type VIII collagen were used to verify that primary cells derived from an explant model of mouse corneal cells were endothelial. A range of phenotypic and functional cellular features were also analysed to assess the usefulness of primary mouse corneal endothelial cultures as a model for human corneal endothelium. These included tight junction protein localization, proliferative responses to growth factor stimulation and ERK1/2 activation following growth factor stimulation. From these analyses, it was shown that primary mouse corneal endothelial cultures provide a representative model of the human corneal endothelium. A similar comparison was also made between primary mouse corneal endothelial cultures and an SV40 transformed mouse corneal endothelial cell line. Studies revealed significant differences in propensity to proliferate, junctional integrity, ERK1/2 activation, expression of apoptotic proteins and sensitivity to staurosporine-induced apoptosis between primary cells and the SV40 transformed cell line, suggesting that the SV40 transformed cell line is a less appropriate model for primary mouse corneal endothelial cells. In conclusion, the derivation and characterisation of mouse primary corneal endothelial cells provides a better model of the corneal endothelium, that offers greater understanding of cellular responses and which may eventually lead to the development of alternative therapies for primary corneal endotheliopathies.

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The ability to measure ocular surface temperature (OST) with thermal imaging offers potential insight into ocular physiology that has been acknowledged in the literature. The TH7102MX thermo-camera (NEC San-ei, Japan) continuously records dynamic information about OST without sacrificing spatial resolution. Using purpose-designed image analysis software, it was possible to select and quantify the principal components of absolute temperature values and the magnitude plus rate of temperature change that followed blinking. The techniques was examined for repeatability, reproducibility and the effects of extrinsic factors: a suitable experimental protocol was thus developed. The precise source of the measured thermal radiation has previously been subject toe dispute: in this thesis, the results of a study examining the relationships between physical parameters of the anterior eye and OST, confirmed a principal role for the tear film in OST. The dynamic changes in OST were studied in a large group of young subjects: quantifying the post-blink changes in temperature with time also established a role for tear flow dynamics in OST. Using dynamic thermography, the effects of hydrogel contact lens wear on OST were investigated: a model eye for in vivo work, and both neophyte and adapted contact lens wearers for in vivo studies. Significantly greater OST was observed in contact lens wearers, particularly with silicone hydrogel lenses compared to etafilcon A, and tended to be greatest when lenses had been worn continuously. This finding is important to understanding the ocular response to contact lens wear. In a group of normal subjects, dynamic thermography appeared to measure the ocular response to the application of artificial tear drops: this may prove to be a significant research and clinical tool.

The study investigated the central and peripheral corneal characteristics of groups of subjects from 20 to 90 years of age to assist the understanding of ageing changes in the cornea, and to see whether relationships between ocular parameters were revealed. After age 45 the corneal horizontal radius of curvature gradually decreased with age. This trend was shown by the Aston University subjects (group B). The effect was very significant for the hospital patients undergoing biometry before cataract extraction operation (group D). Vertical radius of curvature showed a slight decrease with age after age 45, but similar to corneal eccentricity, this showed no significant age effect. Corneal astigmatism progressed from with the rule towards against the rule, particularly after age 60. The shift seemed mainly due to the decreasing horizontal corneal curvature. In biometry no significant age relation was found for axial length, but a significant relation was found between curvature and axial length in the larger group D. Lens thickness showed a very significant relation to age and to axial length, but no significant relation to corneal curvature. Anterior chamber depth showed a very significant relation to age, lens thickness and axial length, but no significant relation to corneal curvature. A significant age effect was found for corneal thickness decreasing with age for the central, nasal and temporal regions of the right eye. Analysis of the biometry results indicated the influence of two major factors. Firstly, the natural growth of the eye in youth, leading to greater values of axial length, radius of corneal curvature, lens thickness and anterior chamber depth. Secondly, the typical ageing changes where the increasing lens thickness caused a reduction in anterior chamber depth.