Desarrollo de un método para la determinación de la refracción objetiva de un paciente basado en la respuesta pupilar

Résumé

Subjective refraction is based on a question-and-answer interaction with the patient to evaluate their visual quality though lenses of varying power. Subjective refraction is currently considered the gold standard for optical correction prescription. However, it is a tedious process and there is an ongoing endeavor to develop an objective method not involving the active participation of the subject, that is, without their answering a question or performing a conscious task. Most current objective methods simplify the process but are not accurate enough to be the basis for correction prescription and, therefore, are usually taken as a starting point for subsequent subjective adjustment. In this work, two methods based on pupil monitoring have been evaluated to assess the patient's quality of vision without requiring his conscious response, with the aim of developing a protocol for objective refraction that could be incorporated into a commercial instrument for clinical use. The first method is based on the change of pupil size when the subject detects a visual stimulus. A commercial pupil recording system has been used for these measurements. The results obtained with this method suggest that pupil size can be an indicator of whether a subject has been able to perceive a stimulus. However, it has several limitations for its implementation in a commercial system, such as the need to invest a long time in the measurement protocol to obtain reliable results or the difficulty in isolating the change in pupil size triggered by detection of the visual stimulus from other fluctuations due to a series of environmental or psychological factors. The second method studied is based on the change of pupil position when the subject detects a decentered visual stimulus and instinctively modifies the line of sight to fixate it. After a proof of concept with a commercial pupil recording system, which presented some limitations, a series of experiments were carried out using a prototype developed by the Laboratorio de Óptica at University of Murcia. These experiments confirmed the validity of the method for detecting which visual stimuli the subject was able to distinguish, and this technique was optimized to achieve the subject's objective refraction, which was well correlated to the subjective refraction obtained with the gold standard. Finally, we studied the feasibility of this method to be implemented in the adaptive optics simulator VAO, a commercial instrument developed by Voptica SL with which it is possible to perform objective refraction by aberrometry and subjective refraction with a range of visual tests. Using a simplified version of the protocol the possibility of including this method, once optimized, in future versions of the instrument was demonstrated