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Yuwen Wang, Fuhao Zheng, Hao Chen; Effects of vergence parameters on asthenopia of patients with convergence insufficiency. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1800.
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Patients with convergence insufficiency always have asthenopia during near work., but we found the signs and the symptoms did not match in part of patients. In this study, we want to investigate the effect of vergence parameters on asthenopia of patients with convergence insufficiency, and find some parameters to reflect the level of asthenopia.
We recruited 58 patients with convergence insufficiency from Eye Hospital in Wenzhou Medical University (34 Males, 24 Female, Age 22.67±9.33 years) randomly, excluding strabismus, eye disease, trauma, anisometropia and dysfunction of accommodation. Patients were divided into three groups according to the values of symptom questionnaires using CISS , 20 patients in severe group , 19 in moderate group, and 19 in mild group, respectively. We analyzed the near phoria（PD/PN）, near blur point（PB）, the relationship between recover point（PR） and level of asthenopia. We used the Sheard’s rule: PSheard=2/3*PN-1/3PB, and the difference value between phoria and recovery point: PR-N=PR-PN（PD/PN was exophoria using positive value）. PSheard>0 means it was not match the Sheard’s rule. PR-N<0 means recover point is smaller than phoria.
PN in sever group, moderate group and mild group was -9.50Δ±4.06Δ, -4.95Δ±3.14Δ, -13.63Δ±5.39Δ, respectively, the difference between each two groups are significant(F=19.46, P=<0.001). PSheard in sever group, moderate group and mild group was 1.90Δ±3.02Δ,-2.07Δ±3.00Δ,3.42Δ±3.06Δ, respectively. There are statistically significant difference between moderate group and mild group, and between moderate group and severe group（P<0.05）. In moderate group, PSheard <0, means it matched the Sheard’s rule. The other two groups could not match the Sheard’s rule. PR-N in sever, moderate, mild group was （-5.85Δ±3.24Δ;95%CI：-7.37Δ,-4.33Δ）,（0.63Δ±4.62Δ；95%CI：-1.59Δ,2.86Δ）,（-11.63Δ±6.53Δ; 95%CI：-14.78Δ,-8.49Δ）,respectively. There were statistically significant difference between each two groups(F=29.13, P<0.001) .
The relationship between phoria and recover point will influence the grade of asthenopia of CI patients. Asthenopia may appear when the value of recover point is close to phoria, if PR-N is smaller than 2.86Δ(95%CI of moderate group). And intermittent suppression may appear at near tasks to alleviate symptoms, while PR-N is smaller than -8.49Δ(95%CI of mild lever group).
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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