The authors present a retrospective case review from a database created from a 43-year period of patients with strabismus seen by a single ophthalmologist. Cases were reviewed by either an orthoptist or ophthalmologist for entry into the database. Details relating to demographics, visual acuity, refractive error, ocular alignment and motility were extracted from a total of 4103 patients. A search to identify cases with Duane syndrome revealed 118 cases. Cases with missing data or with other ocular conditions affecting refractive error were excluded. The aim of the analysis was to evaluate whether co-contraction of the extraocular muscles in Duane syndrome results in higher against-the-rule astigmatism (160° to 20° axis). The fellow unaffected eye was used as control. A total of 84 cases of unilateral Duane syndrome were included in the analysis. Most cases had a cycloplegic refraction (n=74), and for the remainder a manifest refraction result was used. There was no statistically significant difference identified between the spherical equivalents of the Duane and fellow eyes. However, Duane eyes had a significantly higher mean cylinder power compared to the fellow eyes. A significantly greater number of Duane eyes had >1 dioptre of astigmatism. No difference was found for with-the-rule astigmatism. A sub-group analysis of those that had undergone surgery revealed similar results to the whole group. The authors suggest misinnervation of the extraocular muscles in Duane syndrome may affect refractive error. However, co-contraction is unlikely to be the mechanism at work. They do speculate about other possibilities and recommend further research in this area. Limitations of the study are acknowledged including the retrospective methodology along with possible restrictions to generalisability due to the source of all cases being a tertiary centre and therefore a likelihood of being of higher complexity. Close monitoring for astigmatism in children with Duane syndrome could potentially help to prevent the development of amblyopia.
Does Duane syndrome have an effect on refractive error?
Reviewed by Lauren Hepworth
Refractive error in unilateral Duane syndrome.
CONTRIBUTOR
Lauren R Hepworth
University of Liverpool; Honorary Stroke Specialist Clinical Orthoptist, Northern Care Alliance NHS Foundation Trust; St Helen’s and Knowsley NHS Foundation Trust, UK.
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