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S.A. Quah, S.B. Kaye; Binocular Visual Field Changes following Surgery in Esotropic Amblyopia . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4831.
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© ARVO (1962-2015); The Authors (2016-present)
Background: The size of the binocular visual field (BVF) is determined by the extent to which the monocular visual fields (MVF) summate. Although the BVF is reduced in esotropic amblyopia, there may be an improvement following surgery. It is unclear, which factors can be used to predict a postoperative improvement in the BVF. Purpose: To determine in children, the extent to which the BVF changes following surgery for large angle esotropia and whether this change can be predicted, using a prism to correct the pre-operative angle of deviation. Methods: MVF and BVF were measured using Goldmann kinetic perimetry in healthy adults (n=6) using a range of prisms (-10PD to +30PD). Visual fields were then measured in normal children (n=19) and children with large angle esotropic amblyopia (n=28). In 13 children undergoing surgery, visual fields were measured preoperatively with and without a prism correcting the size of the esotropia. A further evaluation of these children was made at 2 and 18 months postoperatively. Repeatability measurements were performed in a subgroup of 15 children to establish 95% confidence intervals to assess the reliability of changes in the surgical group. Results: In healthy adults there was no significant effect of varying the power of a prism on the horizontal or vertical extent of MVF or BVF. There was no significant difference in the MVF in children with and without strabismus. There was a significant reduction in the BVF and in the ratio of the BVF to MVF between normal children (138.42, 0.59) and children with esotropic amblyopia (119.76, 0.57) (p=0.01, p=0.02). Post-operatively, there was a significant improvement in the BVF (p=0.02), which was maintained at 18months. The increase in BVF was significantly greater than the variation in repeated fields (p=0.04), with 8 of 13 children showing an increase in the BVF above the 95%CI of the repeatability measurements. The size of the preoperative BVF with a prism correlated with the postoperative BVF (r=0.90 p=0.001). Approximately 81% of the change in BVF could be predicted from the pre-operative BVF using a prism to correct the deviation. Conclusion: Children with esotropic amblyopia demonstrate a significant reduction in their BVF. The potential increase in the BVF following surgery can be predicted by using a prism to correct the preoperative angle. Patients with a BVF/MVF approaching that found in normal children may not show an improvement in the extent of their BVF following surgery.
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