Gail V. Morton

Treatment of Partly Accommodative Esotropia With a High Accommodative Convergence-Accommodation Ratio

We conducted a prospective, randomized, masked comparison of two treatments for the nonaccommodative element in esotropic patients with a high accommodative convergence-accommodation ratio. One group received symmetric medial rectus recessions with posterior fixation sutures; the other received symmetric medial rectus recessions without posterior fixation sutures but augmented according to formula taking into account the near deviation. Previous experience had suggested that our surgical formula based solely on the distance deviation would lead to excessive undercorrections. A higher percentage of the augmented recession group achieved satisfactory alignment and were able to discontinue wearing bifocals postoperatively than the posterior fixation group. The data also showed a trend (though not statistically significant) suggesting that more members of the augmented recession group were able to discontinue wearing spectacles entirely. We concluded that the posterior fixation suture technique is not as effective as the augmented recession technique for the treatment of partly accommodative esotropia with a high accommodative convergence-accommodation ratio.

The Relationship Between Dissociated Vertical Divergence (DVD) and Head Tilts

INTRODUCTION Dissociated vertical divergence (DVD) has been associated with manifest head tilts. Also, DVD has been described as demonstrating a characteristic response to forced head tilt by increasing the size of the DVD on contralateral tilt. METHODS A series of 116 consecutive patients with DVD associated with infantile esotropia were examined according to a predetermined protocol between 1989 and 1994. Each patient was examined for a manifest head tilt. Also, the response of the DVD to forced ipsilateral and contralateral head tilt was analyzed. In addition, 100 consecutive patients with manifest head tilts were examined and the etiology of the tilt determined. RESULTS A manifest head tilt was present in 35% (26/74) of patients with an ocular fixation preference and no prior vertical muscle surgery. None of the patients with alternating fixation and a history of no vertical muscle surgery manifested a head tilt. Most patients responded in the classically described manner by increasing the size of the DVD on forced contralateral tilt and decreasing the size of the DVD on ipsilateral tilt. Atypical responses were not related to the presence of oblique overaction. DVD was the etiology in 9 of 100 consecutive patients with a manifest head tilt. CONCLUSIONS Patients with DVD often manifest a head tilt. Most respond by increasing the size of the DVD on forced contralateral head tilt and decreasing on ipsilateral tilt. Atypical responses did not appear to be influenced by oblique overaction. DVD is a relatively frequent cause of manifest head tilts.

Variation in axial length and anatomical landmarks in strabismic patients.

The authors calculated axial length measurements in 185 consecutive patients undergoing strabismus surgery and found a mean measurement of 21.98 +/- 1.59 mm (range, 18.75-25.37 mm). Although significant correlation between axial length, refractive error, and age was found, wide variation was present, which indicates that age and refractive error could not accurately predict axial length. Based on a formula derived from a geometric model to determine the equator-limbus distance, given the axial length, the authors found that the equator had a mean distance from the limbus of 11.56 +/- 1.75 mm (range, 9.10-13.76 mm). Based on the variability found at surgery for the insertion-limbus distance, the number of millimeters of recession of the medial rectus from the insertion that would have been necessary to place it at the equator ranged between 3.5 and 8.5 mm in this series, and for the lateral rectus, 3.5 mm to 7.0 mm. The number of millimeters necessary to recess the lateral rectus to its point of tangency with the globe ranged between 9.5 and 14.4 mm.