Purpose: The purpose of this study is to identify the characteristics of strabismus that coexist with nanophthalmos and to report the results of strabismus surgery performed on these small eyes.
Design: Retrospective, consecutive, noncomparative interventional case series.
Participants: Fifteen bilateral nanophthalmic patients, of whom five underwent horizontal muscle surgery, were included in this study.
Methods: Chart review. The clinical examination included visual acuity assessments using the linear Snellen and the Lea charts, slit-lamp and fundus examinations, intraocular pressure, and axial length measurements. The orthoptic examination consisted of measurements of ocular deviations using the prism cover test with an accommodative target at both near and distance with and without refractive correction, assessment of ocular motility with ductions and versions, binocularity with Worth's four-dot test, and the Titmus test. Amblyopia was treated with part-time occlusion. Surgery for the correction of esotropia included bilateral medial rectus recessions or recess-resect procedures.
Main outcome measures: Magnitude of strabismic deviation, best-corrected visual acuity, and the level of binocular vision achieved were monitored.
Results: The average age of enrollment in the study was 4.7 (range, 1-12) years. The patients were followed for an average of 7.0 (range, 4-14) years. The mean axial length was determined as 18.4 mm (range, 15.5-20.7). The mean refractive error in spherical equivalents was measured as +9.9 and ranged between +4.0 and +15.0 diopters. Five patients (33%) had nonaccommodative esotropia, four (27%) had partially refractive esotropia, four (27%) had microesotropia, and two (13%) had exotropia. Five patients, all having nonaccommodative esotropia, underwent surgery for the correction of ocular misalignment. Diminishing the surgical dose in these small eyes resulted in undercorrections. Despite patching, 3 patients (20%) had unilateral and 12 patients (80%) had bilateral amblyopia at the conclusion of the study.
Conclusions: Strabismus in nanophthalmos usually manifests as nonaccommodative and partially refractive esotropia. Medial rectus recession should be applied with care to prevent adduction deficit and convergence insufficiency. Otherwise, there seems to be no need for decreasing the surgical dose with regard to the smaller axial length. Amblyopia tends to be persistent in these patients.