Study of Fixation Using Micro Perimeter (MP-1) in Amblyopia and Strabismus

• Published in: JAPANESE ORTHOPTIC JOURNAL Vol. 43; pp. 81 - 86
• Main Authors: Ohira, Ryo, Shioya, Naoko, Nomura, Mika, Watanabe, Chigusa, Miura, Kazuma, Takano, Masahiko
• Format: Journal Article
• Language: English; Japanese
• Published: JAPANESE ASSOCIATION OF CERTIFIED ORTHOPTISTS 2014
• Subjects: amblyopia; fixation; Micro Perimeter; RFE; strabismus
• ISSN: 0387-5172; 1883-9215
• DOI: 10.4263/jorthoptic.043F103

[Purpose] The relationship between visual acuity (VA) and fixation stability measured by the Micro Perimeter (MP-1) was reported and compared between the right and left eyes in patients with amblyopia and strabismus. [Materials and Methods] A total of 16 patients (9 with amblyopia and 7 with strabismus) who could endure the MP-1 fixation test for 30 seconds were included. The assessment of fixation stability was analyzed by the bivariate contour ellipse area (BCEA). The range of fixation effectiveness (RFE) was the elliptical area covering 68.2% of the fixation point tested within 30 seconds. In this study, square degree (Sqd) was used as the unit for the RFE. The studied eye was defined as the eye with better VA. In patients whose both eyes had the same VA, the right eye was the studied eye. In patients with strabismus, the eye that fixated was the studied eye. The fellow eye served as the control. The correlation between the RFE and VA was separately evaluated for the studied and fellow eyes. In addition, we also examined the VA and RFE differences between both eyes. The Pearson correlation coefficient was used for analysis. [Results] In the studied eyes, the RFE was relatively small and it varied from 0.02 to 1.40 Sqd even in the eyes with VA of 1.2. It did not correlate with VA (P = 0.55). In the control eyes, the RFE was greater in patients with poor VA (P < 0.01). A significant positive correlation with VA was observed. The eyes with a greater VA difference between both eyes also resulted in a greater RFE difference. A significant positive correlation was observed between the VA and RFE differences (P < 0.01). [Conclusion] The MP-1 enabled the quantitative assessment of fixation stability in this study. This indicated that the fixation test using the MP-1 may be an effective method for evaluating visual function by comparing the quantified fixation stability of both eyes.