Caracterització dels paràmetres corneals per a l'adaptació de lents de contacte en casos de queratocon

Introduction: The characterization of the corneal surface and the classification of keratoconus into diverse severity stages is a field of research in constant evolution, not only because of technology advances, but also with the definition of new parameters that allow a better understanding of the geometry, status and evolution of affected eyes, as compared with healthy eyes. Within the evolution of our knowledge about keratoconus, it is increasingly relevant to analyze the changes caused by this pathology to the morphology of the peripheral cornea with the purpose of successfully developing large diameter corneal contact lenses (CL) for these patients, to improve visual quality and comfort, with minimum interference with ocular physiology. Current Investigations: The objective of this series of studies was to improve our knowledge of corneal geometry as a whole and, in particular, to determine if corneal changes occurring in keratoconus are mainly corneal, limbal / scleral, or a combination of both. This information is key to design and fit large diameter corneal CL in patients with different stages of the condition, as a complementary or alternative solution to current fitting strategies. With this purpose in mind, Scheimpflug images at different corneal meridians were used to analyse several corneal and anterior segment parameters of eyes of patients with keratoconus at different stages of the condition. As such, one of the novel aspects of the present study consisted in a complete analysis of the anterior segment, not limited to parameters provided by the software of the Pentacam HR®, but also defining new parameters, not available in the current version of the software. These parameters, manually measured on Scheimpflug images, included a newly defined parameter (DL, or distance to the lens, distance from the end point of the corneal sagittal line to the anterior surface of the lens) which proved very useful for the required corneal-limbal characterization. The following step was to analyse the corneal periphery by measuring the corresponding peripheral corneal angles (at a chord length between 8.6 and 12.6 mm) and the degree of peripheral revolution symmetry (defined as the difference between the smallest and largest peripheral corneal angle for a particular eye). This was accomplished with a newly developed methodology, as the areas under study had not been previously explored with Scheimpflug images. Finally, a new design for a large diameter corn