Fredrik P Källmark1, Jan Ygge. 1. Unit of Optometry, St. Erik Eye Hospital, Department of Clinical Neuroscience, Karolinska Institutet, Polhemsgatan 50, Stockholm, Sweden. fredrik.kallmark@ste.ki.se
Abstract
BACKGROUND: Visual field (VF) examinations provide important information about diagnosis and follow-up in many ocular and visual pathway disorders. Previous studies have shown that fixation stability can be measured very exactly around the center of the fixation point with SLO. The importance of measuring fixation during microperimetry in the absence of field defects is to learn more about the normal fixation pattern. This is of interest since changes in fixation pattern due to pathology can occur prior to detectable changes in the macula or visual pathway. MATERIAL/ METHODS: Thirty-one adult subjects with healthy eyes were recruited from the staff of the Section of Ophthalmology and Vision, Department of Clinical Neuroscience, Karolinska Institutet. The fixation pattern in one randomly selected eye from each subject was investigated with the SLO using the fixation control function in the microperimetry technique. RESULTS: The results showed that the fixation pattern had a mean center of gravity located at a mean absolute distance of 0.27 degrees from the fixation point (FP) and a directional predominance of the fixation pattern was found in that the fixations were more frequently distributed vertically than horizontally. CONCLUSIONS: The computerized fixation control when performing microperimetry with the SLO provides information about the fixation pattern which cannot be obtained with standard clinical perimetry techniques.
BACKGROUND: Visual field (VF) examinations provide important information about diagnosis and follow-up in many ocular and visual pathway disorders. Previous studies have shown that fixation stability can be measured very exactly around the center of the fixation point with SLO. The importance of measuring fixation during microperimetry in the absence of field defects is to learn more about the normal fixation pattern. This is of interest since changes in fixation pattern due to pathology can occur prior to detectable changes in the macula or visual pathway. MATERIAL/ METHODS: Thirty-one adult subjects with healthy eyes were recruited from the staff of the Section of Ophthalmology and Vision, Department of Clinical Neuroscience, Karolinska Institutet. The fixation pattern in one randomly selected eye from each subject was investigated with the SLO using the fixation control function in the microperimetry technique. RESULTS: The results showed that the fixation pattern had a mean center of gravity located at a mean absolute distance of 0.27 degrees from the fixation point (FP) and a directional predominance of the fixation pattern was found in that the fixations were more frequently distributed vertically than horizontally. CONCLUSIONS: The computerized fixation control when performing microperimetry with the SLO provides information about the fixation pattern which cannot be obtained with standard clinical perimetry techniques.