PUPIL VISUAL TRACKING ALGORITHMS FOR AUTOMATED STATIC PERIMETRY SYSTEMS

Some diseases, for instance, a glaucoma, cause visual field defects. For the timely diagnostics of such defects, various methods are used. One of the state-of-the-art diagnostic methods is automated static perimetry. The method of static perimetry consists in the light sensitivity determination in different parts of the visual field using stationary objects of variable luminosity. When scanning the visual field in this way, an important factor is the control of gaze fixation at the fixation point. The greatest accuracy in determining the gaze fixation position is achieved by the method of the pupil visual tracking using a video camera.In this paper, four groups of visual tracking algorithms are considered: segmentation-based methods, correlation methods, methods based on optical flow and on weighted average. An experimental comparison of these methods was carried out using the base of video recordings obtained in the automatic static perimetry apparatus. On these videos the ground truth tracks of pupil were marked. The comparison was conducted according to two criteria: center location error and tracking length. It is shown that only the weighted average method has an acceptable tracking length.

Right Homonymous Hemianopia: A Clinical Case Report of Schizencephaly

Purpose: To report a case of a 56-year-old male with right homonymous hemianopia. Methods: Retrospective descriptive study of a case report based on information from clinical records, patient observation and analysis of complementary diagnostic tests. Results: An asymptomatic 56-year-old male presented to our hospital for a routine ophthalmic examination. The best-corrected visual acuity was 20/20 in the right eye (RE) and in the left eye (LE). Pupillary function, intraocular pressure, external segment examinations and slit-lamp biomicroscopy were normal, bilaterally. Fundoscopy showed a cup-to-disc (C/D) ratio in the RE of 0.3 and of 0.4 in the LE. Retinal nerve fiber layer (RNFL) thickness measured by spectral domain optical coherence tomography revealed thinning of the superior, temporal and nasal RNFL in the RE and thinning of the superior, inferior and temporal RNFL in the LE. Automated static perimetry showed right homonymous hemianopia. Brain computed tomography (CT) showed an open-lip schizencephaly with a significant reduction of the left brain parenchyma. Conclusions: Despite the large visual defect, the patient was unaware of it and had an active professional life. This is an interesting case because despite the extensive morphological abnormalities seen on brain CT there is a relatively small functional repercussion.