Original Articles
Assessment of central and peripheral fusion and near and distance stereoacuity in intermittent exotropic patients before and after strabismus surgery

https://doi.org/10.1016/S0002-9394(99)00079-3Get rights and content

Abstract

PURPOSE: To determine whether central fusion and distance stereoacuity are useful as objective measures in assessing the need for and success of surgery for intermittent exotropia (X[T]).

METHODS: A prospective, institutional, clinical trial was conducted of 26 consecutive patients with X(T) who were undergoing strabismus surgery in whom fusion (central and peripheral) and stereoacuity (at near and distance) were assessed preoperatively and postoperatively, as well as in 112 normal subjects. To obtain accurate measurements with sensory tests, the lower age was limited to 5 years for inclusion. A successful surgical alignment was defined as an exotropia of 10 prism diopters or less at 6 m. Sensory and motor outcome measures were determined 1 year after surgery.

RESULTS: The successful surgical alignment rate was 69%. All patients with X(T) demonstrated peripheral fusion, whereas 35% demonstrated central suppression preoperatively and postoperatively. Central fusion was not predictive of surgical outcome (P = .078); however, there was a trend toward less surgical success in patients with central suppression. Patients with X(T) exhibited good near stereoacuity before and after surgery. Distance stereoacuity in patients with X(T) preoperatively was significantly diminished compared with normal subjects (P < .001) and was improved in 58% postoperatively. Patients who achieved successful surgical alignment had a greater likelihood of demonstrating distance stereoacuity improvement postoperatively than patients who failed to achieve successful surgical alignment (P = .003). Patients with central suppression were unlikely to improve their distance stereoacuity postoperatively (P = .014).

CONCLUSIONS: Successful surgery may improve distance stereoacuity. Better distance stereoacuity and central fusion are frequently associated with better surgical success in X(T).

Section snippets

Methods

Between 1994 and 1997, all consecutive patients with X(T) who were undergoing surgery as the initial surgical management of this condition at the Gulhane Military Medical Academy Eye Clinic were evaluated for their motor and sensorial status preoperatively and postoperatively. Criteria required for inclusion in this prospective, institutional, clinical trial included: no more than 2 lines of difference in best-corrected visual acuity between both eyes as determined by Snellen letters or

Results

During the enrollment period, 38 patients with X(T) underwent surgery at our clinic. This study includes the results of measurements of 26 patients (68%) with X(T) who met the inclusion criteria and underwent surgical correction; 12 (32%) were eliminated on the basis of the aforementioned exclusion criteria.

Of 26 patients with X(T), 18 (69%) had a successful alignment at distance, and eight (31%) had an unsuccessful alignment, depending on their measurements 1 year after surgery. As shown in

Discussion

The data in this study suggest that the distance alternate-letter suppression test should be used to assess sensorial status in patients with X(T) for several reasons. First, it was found that 35% of patients with X(T) demonstrated central suppression preoperatively and postoperatively with this test, in contrast to normal subjects, none of whom exhibited central suppression. Second, a correlation was shown between both preoperative and postoperative central fusion and distance stereopsis. The

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