Applicability of scanning laser ophthalmoscopy microperimetry on the fixation patterns of monofixation syndrome

Objective: To investigate the monocular fixation pattern and characteristics in patients with monofixation syndrome using scanning laser ophthalmoscopy (SLO) microperimetry (MP). Methods: Twenty-four patients older than 5 years who had 8 prism diopters (PD) or less of deviation after surgery were analyzed. The A group included 14 patients with infantile esotropia (ET), and 10 patients with acquired ET were assigned to B group. The monocular fixation pattern and characteristics of all patients were investigated using SLO MP. Central or mild eccentric fixation was defined as eyes with more than 50% of the fixation points located within the 2° diameter circle centred on the fovea. Results: Mean ages at the time of surgery were 27 (range, 11-48) months in A group and 75 (range, 27-166) months in B group. Mean ages at the time of MP examination were 117 (range, 64-210) months in A group and 106 (range, 64-167) months in B group. Mean distant and near angles of esodeviation were -1.7 PD (-8 to 8) and -2.7 PD (-8 to 6) in A group and 0.6 PD (-2 to 8) and -0.4 PD (-2 to 0) in B group. Central or mild eccentric fixation was present in 8 patients (57%) and moderate or severe eccentric fixation in 6 patients (43%) in A group. In contrast, all patients in B group had central or mild eccentric fixation (p = 0.022). Conclusions: Postoperative moderate eccentric or severe eccentric fixations were observed in 43% of patients with infantile ET in either eye; however, all patients with acquired ET showed central or mild eccentric fixation in both eyes.