Sherry L. Fawcett

Why does early surgical alignment improve stereoacuity outcomes in infantile esotropia

PURPOSE Recent studies of infantile esotropia suggest that early surgical alignment may enhance stereopsis and that alignment during the first 6 months of life may be optimal. Early surgery both establishes alignment during an early critical period for the development of stereopsis and minimizes the duration of misalignment. Here we examine the role of these 2 factors in promoting improved stereopsis outcomes. METHODS Participants were 129 consecutive patients enrolled in a prospective study of infantile esotropia who were followed up for a minimum of 5 years. At ages 5 to 9 years, Randot stereopsis was evaluated. RESULTS Multiple linear regression indicated that duration of misalignment, but not age at alignment or age at onset, was a significant factor in determining random dot stereopsis outcomes. Moreover, patients with stereopsis were less likely to have a loss of horizontal eye alignment requiring surgery than patients without stereopsis (14% versus 32%; z = 1.96, P =.05). Patients with stereopsis were also less likely to have dissociated vertical deviation than patients without stereopsis (25% versus 63%; z = 3.36, P <.001). CONCLUSIONS The results suggest that early surgical alignment is associated with better stereopsis in those patients with infantile esotropia who were treated during the first 24 months of life, because early surgery minimizes the duration of misalignment, not because alignment is achieved during an early critical period of visual maturation. Random dot stereopsis can also be achieved in patients with alignment provided that the duration of misalignment is not prolonged. Improved outcomes of random dot stereopsis are associated with more stable long-term alignment outcomes.

Risk factors for abnormal binocular vision after successful alignment of accommodative esotropia.

PURPOSE The purpose of this study was to identify clinical factors associated with abnormal binocular vision outcomes among children with accommodative esotropia (ET) whose eyes were successfully realigned with spectacles only or with spectacles and surgery. METHODS The participants were 69 children with accommodative ET who were followed up prospectively from the time of diagnosis. Clinical factors examined in this study included high accommodative convergence-to-accommodation (AC/A) relationship, high hyperopia, anisometropia, age of onset, and duration of eye misalignment. Binocular vision was assessed using measures of stereopsis, fusional vergence, sensory foveal fusion, and motion visual-evoked potential (mVEP). RESULTS Children with a high AC/A relationship are 2.2 times more likely to have an absence of fusional vergence than are children with a normal AC/A relationship. Children having a duration of constant eye misalignment >/= 4 months before being successfully treated are 4.6 times more likely to have abnormal stereopsis, 33 times more likely to have no stereopsis, 37 times more likely to have an absence of fusional vergence, 31 times more likely to have an absence of sensory foveal fusion, and 17 times more likely to have an asymmetric mVEP response than children with a duration of constant ET diagnosed at 0 to 3 months. CONCLUSIONS Following successful eye alignment, as many as 75% of patients with accommodative ET had anomalous binocular vision. A high AC/A relationship poses a significant risk for abnormal fusional vergence only. A constant eye misalignment lasting >/= 4 months poses a significant risk for anomalous binocular vision on all measures studied.

Validity of the Titmus and Randot circles tasks in children with known binocular vision disorders

PURPOSE The Titmus and Randot (version 2) circles tests contain monocular form cues that may enable patients with binocular vision disorders to pass without any measurable stereopsis. The purpose of this study was to evaluate the validity of the Randot and Titmus circles tests for quantifying stereoacuity in children with known binocular vision disorders. METHODS Participants included 170 consecutive children with diverse binocular sensory function ranging from fine to no measurable stereopsis. Stereoacuity was measured using the Randot circles, the Titmus circles, and the Randot Preschool Stereoacuity tests. RESULTS Discrepancies between stereoacuity scores derived using either the Titmus or Randot circles tests and the Randot Preschool Stereoacuity test increased as a function of random-dot stereoacuity. Stereoacuity scores derived using the circles tests showed good agreement with random-dot stereoacuity when stereoacuity was 2.2 log seconds of arc (160 seconds of arc) or better, but they progressively overestimated stereoacuity for poorer random-dot stereoacuity scores. CONCLUSION When measuring stereoacuity using either the Titmus or Randot circles tests in patients with known binocular vision disorders, stereoacuity scores > 2.2 log seconds of arc should be interpreted with caution because it is above this level of stereoacuity that the monocular form cues of each of the tests may invalidate the results.

Risk Factors for Accommodative Esotropia Among Hypermetropic Children

PURPOSE Identification of risk factors for accommodative esotropia may help to determine which children with hyperopia may benefit from early spectacle correction or preventive therapy. METHODS Participants in the family history study were 95 consecutive patients, aged 18 to 60 months, with accommodative esotropia. Participants in the binocular sensory function study were a subgroup of 41 children enrolled in the family history study within 1 month of onset, while the esodeviation was still intermittent. Participants in the hypermetropia study were 345 consecutive patients, ages 12 months to 8 years, with refractive error of +2.00 D or greater and no esodeviation before age 12 months. RESULTS In the family history study, 23% of children with accommodative esotropia had an affected first-degree relative, and 91% had at least one affected relative. In the binocular sensory function study, random-dot stereoacuity was abnormal in 41% of children, whereas an abnormal motion VEP, Worth 4-dot, or positive 4-PD base-out prism responses were present in 4% or less of the children. In the hypermetropia study, patients with a mean spherical equivalent of < +3.00 D and significant anisometropia had a 7.8-fold increased risk for accommodative esotropia over nonanisometropic patients. CONCLUSIONS A positive family history, subnormal random-dot stereopsis, and hypermetropic anisometropia each pose a significant risk for the development of accommodative esotropia. Assessment of these risk factors in conjunction with refractive screening should help to identify those children who are most likely to benefit from early spectacle correction or preventive treatment.