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What characteristics a clinical CSF system has to have?

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Colombo E. , Issolio L. , Santillan J. S. J. , Aguirre R.

Optica Applicata

2009

tom Vol. 39, nr 2

415-428

We discuss the characteristics a system to measure the contrast sensitivity function (CSF) in the ophthalmologic clinic has to have. We propose that this system should be computer based in order to assure flexibility and precision. Besides the original calibration, this equipment needs an auxiliary system to keep the working conditions allowing periodical gamma corrections. We try a calibration method based on visual comparisons and show that it is valid and simple. We propose to use an adaptive psychophysical method to obtain contrast thresholds that assure a good compromise between precision and duration of the whole test. Finally, we propose that the system has to have its own normality curves for the different age ranges allowing the practitioner to perform clinical evaluations. Summing up, we can say that taking into account the above issues, the fidelity of the stimuli will be guaranteed and the challenges entailed in its transference to the clinic will be overcome.

Evaluation of the intraocular scattering through brightness reduction by glare using external diffusers to simulate cataracts

88%

Barrionuevo P. , Colombo E. , Corregidor D. , Jaen M. , Issolio L.

Optica Applicata

2010

tom Vol. 40, nr 1

63--75

In this work, we evaluate the feasibility to determine the intraocular scattering by measuring the brightness reduction by glare. A haploscopic system based on the brightness comparison has been developed. This system allows to compare the brightness of a test with a steady glare source in the field of vision, and another one without it. Our goal is to study the sensibility of the proposed methodology to quantify the intraocular scattering. In this first approach, we use physically and psychophysically characterized external diffusers to simulate different degrees of cataracts. The results have been shown in terms of the glare index. This index increases as the level of filter scattering rises, and even more when the diffuser is set up on only one eye. Besides, the system allows to discriminate among slightly different levels of scattering. The repeatability of the results and the resistance to fraud of the methodology have been analyzed.