Microperimetry MP-3 assessment reveals reduced macular fixation stability in children with concomitant exotropia: a case-control study
- 1Department of Strabismus and Amblyopia， Hainan Eye Hospital and Key Laboratory of Ophthalmology， Zhongshan Ophthalmic Center， Sun Yat-sen University， Haikou， Hainan， China
Abstract
Objective Concomitant exotropia, the most common type of strabismus in children and adolescents, is often accompanied by binocular visual dysfunction, which may disrupt the coordination between the visual and oculomotor systems, thereby affecting macular fixation stability. To assess macular fixation stability in children with concomitant exotropia, this study used the MP-3 microperimeter to explore the differences in fixation stability between these patients and age-matched non-strabismic children, and investigate potential influencing factors for fixation abnormalities. Methods A case-control study was conducted on 40 children diagnosed with concomitant exotropia (exotropia group) admitted to our department and 30 age-matched non-strabismic children (normal control group) between February 2024 and October 2025. Macular fixation function was evaluated under monocular conditions using the MP-3 microperimeter. The percentages of fixation points within the 2° (P1) and 4° (P2) diameter circles, as well as the bivariate contour ellipse area (BCEA) encompassing 68.2%, 95.4%, and 99.6% of fixation points, were recorded. Fixation stability parameters (P1, P2, 68.2%BCEA, 95.4%BCEA, and 99.6%BCEA) were compared between groups, and the correlations of these parameters with clinical characteristics, including strabismus duration, deviation angle, stereopsis, refractive status, and exotropia subtype, were analyzed within the exotropia group. Results There were 40 children in the exotropia group (24 boys and 16 girls, aged 8 to 13 years) and 30 children in the normal control group (16 boys and 14 girls, aged 7 to 12 years). There was a statistically significant difference in P1 values among the dominant eyes of the exotropia group, the deviating eyes of the exotropia group, and the normal control eyes (H=10.673, P=0.005). Pairwise comparisons showed that the P1 values of the dominant eyes (Z=-3.005, P=0.003) and the deviating eyes (Z=-2.620, P=0.009) were significantly lower in the exotropia group than the normal control group, with no significant difference between the dominant and deviating eyes. No significant differences were observed in terms of P2, 68.2%BCEA, 95.4%BCEA, or 99.6%BCEA among the dominant eye and the deviated eye in the exotropia group, and the normal control group. In the exotropia group, no significant correlations were found between any fixation parameters (for either dominant or deviating eyes) and exotropia duration, deviation angle, spherical equivalent, or near stereopsis. However, in the deviating eyes, the degree of astigmatism showed weak positive correlations with P1 (r=0.407, P=0.009) and P2 (r=0.460, P=0.003), and weak negative correlations with 68.2%BCEA (r=-0.404, P=0.010), 95.4%BCEA (r=-0.404, P=0.010) and 99.6%BCEA (r=-0.391, P=0.013), whereas the astigmatism degree of the dominant eye showed no significant correlation with any fixation parameter. Stratified analyses according to binocular visual function (near/far stereopsis, fusion, and simultaneous perception) and strabismus subtype (intermittent/constant) revealed no significant differences in fixation parameters between any subgroups. Conclusion Children with concomitant exotropia exhibit mild impairment of retinal fixation stability, mainly manifested as reduced concentration of fixation points within the central macular region. This decrease is not significantly associated with potential influencing factors such as exotropia duration, deviation angle, refractive status, binocular visual function, or exotropia subtype. The MP-3 microperimeter enables effective and objective assessment of pediatric fixation function, providing reliable quantitative parameters for visual function in strabismus.
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BibTeX
@article{fang2026microperimetry,
title = {{Microperimetry MP-3 assessment reveals reduced macular fixation stability in children with concomitant exotropia: a case-control study}},
author = {Li Fang and He Hong},
journal = {陆军军医大学学报},
year = {2026},
month = oct,
doi = {10.16016/j.2097-0927.202606052},
url = {https://doi.org/10.16016/j.2097-0927.202606052},
note = {CC BY},
}
RIS
TY - JOUR
TI - Microperimetry MP-3 assessment reveals reduced macular fixation stability in children with concomitant exotropia: a case-control study
AU - Li Fang
AU - He Hong
PY - 2026
DA - 2026/10/30
JO - 陆军军医大学学报
DO - 10.16016/j.2097-0927.202606052
UR - https://doi.org/10.16016/j.2097-0927.202606052
AB - Objective Concomitant exotropia, the most common type of strabismus in children and adolescents, is often accompanied by binocular visual dysfunction, which may disrupt the coordination between the visual and oculomotor systems, thereby affecting macular fixation stability. To assess macular fixation stability in children with concomitant exotropia, this study used the MP-3 microperimeter to explore the differences in fixation stability between these patients and age-matched non-strabismic children, and investigate potential influencing factors for fixation abnormalities. Methods A case-control study was conducted on 40 children diagnosed with concomitant exotropia (exotropia group) admitted to our department and 30 age-matched non-strabismic children (normal control group) between February 2024 and October 2025. Macular fixation function was evaluated under monocular conditions using the MP-3 microperimeter. The percentages of fixation points within the 2° (P1) and 4° (P2) diameter circles, as well as the bivariate contour ellipse area (BCEA) encompassing 68.2%, 95.4%, and 99.6% of fixation points, were recorded. Fixation stability parameters (P1, P2, 68.2%BCEA, 95.4%BCEA, and 99.6%BCEA) were compared between groups, and the correlations of these parameters with clinical characteristics, including strabismus duration, deviation angle, stereopsis, refractive status, and exotropia subtype, were analyzed within the exotropia group. Results There were 40 children in the exotropia group (24 boys and 16 girls, aged 8 to 13 years) and 30 children in the normal control group (16 boys and 14 girls, aged 7 to 12 years). There was a statistically significant difference in P1 values among the dominant eyes of the exotropia group, the deviating eyes of the exotropia group, and the normal control eyes (H=10.673, P=0.005). Pairwise comparisons showed that the P1 values of the dominant eyes (Z=-3.005, P=0.003) and the deviating eyes (Z=-2.620, P=0.009) were significantly lower in the exotropia group than the normal control group, with no significant difference between the dominant and deviating eyes. No significant differences were observed in terms of P2, 68.2%BCEA, 95.4%BCEA, or 99.6%BCEA among the dominant eye and the deviated eye in the exotropia group, and the normal control group. In the exotropia group, no significant correlations were found between any fixation parameters (for either dominant or deviating eyes) and exotropia duration, deviation angle, spherical equivalent, or near stereopsis. However, in the deviating eyes, the degree of astigmatism showed weak positive correlations with P1 (r=0.407, P=0.009) and P2 (r=0.460, P=0.003), and weak negative correlations with 68.2%BCEA (r=-0.404, P=0.010), 95.4%BCEA (r=-0.404, P=0.010) and 99.6%BCEA (r=-0.391, P=0.013), whereas the astigmatism degree of the dominant eye showed no significant correlation with any fixation parameter. Stratified analyses according to binocular visual function (near/far stereopsis, fusion, and simultaneous perception) and strabismus subtype (intermittent/constant) revealed no significant differences in fixation parameters between any subgroups. Conclusion Children with concomitant exotropia exhibit mild impairment of retinal fixation stability, mainly manifested as reduced concentration of fixation points within the central macular region. This decrease is not significantly associated with potential influencing factors such as exotropia duration, deviation angle, refractive status, binocular visual function, or exotropia subtype. The MP-3 microperimeter enables effective and objective assessment of pediatric fixation function, providing reliable quantitative parameters for visual function in strabismus.
SN - 2097-0927
ER -