Unilateral recession and resection in Duane syndrome.

PURPOSE: To assess the efficacy of lateral rectus resection with medial rectus recession in the affected eye of patients with Duane retraction syndrome (DRS) with esotropia and limited abduction, compared with bilateral medial rectus recessions. METHODS: The charts of 9 patients with DRS who underwent a recession-resection procedure and 10 patients with DRS who underwent bilateral medial rectus recessions were reviewed. Ocular ductions (graded from 0 = full duction to -4 = total deficit), severity of retraction, alignment, head position, and binocular single vision field (for study group only) were recorded before and after surgery. RESULTS: Before surgery, the study and control groups did not differ in mean primary position esotropia (16.9 and 18.8 PD, respectively), face turn (16.5 degrees and 15.0 degrees, respectively), average limitation of abduction (-3.9 and -3.7, respectively), or adduction (-0.1 and -0.3, respectively). After surgery, both groups had similar mean face turns (3.9 degrees and 1.0 degrees ), esotropia (3.3 PD and 1.0 PD), and abduction limitation in the affected eye (-2.4 and -2.6). However, mean adduction was significantly worse in the control group than in the study group (-1.5 vs -0.6, P = .02). Globe retraction improved in all control subjects. It worsened in 5 study subjects and did not improve in the other 4. In the study group, 1 patient required reoperation for undercorrection and another was overcorrected. CONCLUSION: Seven of 9 patients with DRS, selected on the basis of esotropia, limited abduction, and mild retraction, benefited from a recession-resection procedure. Abduction improved to the same degree as seen after bilateral medial rectus recessions, with less tendency to limit adduction.

The maximum motor fusion test: a parameter for surgery for acquired esotropia.

PURPOSE: The purpose of this study was to determine whether surgery for acquired esotropia based on the maximum capacity for motor fusion measured with a prism bar could be used to increase the number of millimeters of bilateral medial rectus recession that could be performed without producing an early overcorrection or a late consecutive exotropia, as a way safely to reduce the need for postoperative wear of glasses or a bifocal. METHODS: Category I patients had residual deviations of esotropia (ET) of 12 PD or more with distance fixation, measured after a full hyperopic correction of +1.50 to +3.25 was placed, and had no significant anisometropia or astigmatism. Category II patients had residual deviations of esotropia of less than 11 PD with distance fixation and had residual deviations of esotropia with near fixation (ET') of at least 10 PD more than esotropia with distance fixation ("clinical high AC/A"). Category III patients had had previous bilateral medial rectus muscle recessions and had recurrent esotropia with near fixation of more than 10 PD. For patients in categories I and II, bilateral medial rectus muscle recessions were performed by using a published dose-response table from the national Prism Adaptation Study but with the maximum capacity for motor fusion as the input parameter instead of the prism-adapted angle. Patients in category III received re-recessions of one or both medial rectus muscles, according to a previously published system, with the distance fusional amplitude as the input parameter. RESULTS: In category I, 24 of 30 (80%) patients needed no glasses after surgery, 1 of 30 had esotropia, and 2 of 30 had exotropia (XT) (10% reoperation rate). In category II, 35 of 36 (98%) patients needed no bifocals after surgery, and 3 of 36 had exotropia (9% reoperation rate). In category III, 10 of 10 patients needed no bifocals, and 2 of 10 had exotropia (20% reoperation rate). CONCLUSIONS: When a postoperative reduction in dependence on continuous wear of an optical appliance is a reasonable goal, the maximum motor fusional capacity, measured with a prism bar, is a good parameter for surgical design.

A three dimensional surgical dose-response schedule for lateral rectus resections for residual congenital/infantile esotropia after large bilateral medial rectus recessions.

PROBLEM: A series of overcorrections after this surgical sequence. SUBJECTS & METHODS: Forward stepwise multiple regression analysis of the effect of bilateral lateral rectus resections, retrieved and tabulated retrospectively from the clinical charts of 50 children with infantile esotropia who had significant residual non- accommodative esotropia after bilateral medial rectus recessions. Analysis allowed for selection among linear and quadratic forms of two relevant predictor variables: the mm of previous bilateral medial rectus recession and the prism diopters of residual esotropia. RESULTS: We found a correlation between the effect of the second surgery (bilateral LR resections) and the two variables. This relation could be expressed by a surgical dose-response schedule-surface with the formula: [2.39 + 0.26 (mm MR recession) Squared + 0.41 (mm LR Resection) Squared = prism diopters of effect]. A corresponding schedule (table) with these two parameters was developed to facilitate clinical application. To test and prove this schedule, we re-studied 19 of the 50 original cases who had had surgery, fortuitously, +/-0.3 mm of our new surgical dose- response surface-schedule plus 10 new cases performed according to the new surface-schedule. For these 29 cases there was only one "failure" at 6 months postop' (3%). As a control, for the 31 cases of the original 50 whose surgery had not been within +/- 0.3 mm of the new schedule, 7/31 (23%) were "failures", all overcorrections. ("Failure" vs. "success" - there were only two categories of outcome - was defined as an esotropia over 8 PD or exophoria over 6 PD.) CONCLUSION: This difference in results, expressed as "successes" of 28/29 vs 24/31, or 97% vs 77% gave, on statistical analysis, a p=0. 053 of rejecting the null hypothesis, which is considered a valid "trend" or marginally "statistically significant" and definitely "clinically-medically significant". We have adopted the regular application of our new surgical dose- response schedule in these cases and recommend it for all such cases. binocular vision; complications, surgical; dose-response surgical schedule; esotropia, congenital/infantile; lateral rectus muscle, resection; outcomes; overcorrections; strabismus surgery; study, retrospective, clinical; surgery, strabismus.

Antielevation syndrome after bilateral anterior transposition of the inferior oblique muscles: incidence and prevention.

BACKGROUND: Unilateral and bilateral anterior transpositions of the inferior oblique muscle (ATIOs) for primary inferior oblique (IO) muscle overaction may produce apparent new or recurrent overaction of the contralateral IO muscle. This effect has been termed "antielevating" and can produce overaction of the contralateral elevators in adduction that mimics recurrent or new overaction of the IO muscle of the other eye. This phenomenon may be termed the antielevation syndrome (AES). Kushner has hypothesized that this complication of the ATIO is produced primarily by the posterior fibers of the IO muscle. The purpose of this study is to correlate the frequency of this syndrome in a large series of patients with the mm of lateral displacement (spreading) of the IO muscle reattachment site. METHODS: There was a combination of 123 patients who received ATIO from Mims and 77 patients who received ATIO from Kushner. ATIO was performed according to a previously published technique. RESULTS: All 16 patients (14 from Mims and 2 from Kushner) with AES had received bilateral anterior transposition of the posterior fibers of the IO muscle to at least 2 mm anterior to the lateral end of the inferior rectus (IR) muscle with spreading laterally 3 to 5 mm. Among children who had the posterior fibers of their IO muscles placed 2 to 4 mm anterior to a line drawn laterally from the insertion of the IR muscle, the incidence of AES was significantly larger with more spreading out of the new IO muscle insertion. CONCLUSIONS: AES may be prevented by attaching the posterior fibers of the IO muscle no more than 2 mm lateral to the IR muscle insertion site. This complication responds to bilateral nasal IO muscle myectomy in many cases.

Forming and teaching true knots for strabismus surgery.

I describe a system for ensuring the formation of true knots in the locking bites in strabismus surgery. I also present a method for teaching this system to residents that makes use of a piece of cotton or nylon rope, a cotton mop refill, and the end of a garden rake.

Bilateral anterior transposition of the inferior obliques.

Sixty-one children with bilateral overaction of the inferior oblique muscle with concurrent or previous infantile esotropia received bilateral inferior oblique recessions with anteriorization to a point 2 to 4 mm anterior to the lateral end of the inferior rectus insertion. Subsequent reoperation for recurrent overaction of the inferior obliques was needed in only one case. Also, substantial reduction in dissociated vertical deviation (DVD), when present, and almost complete absence of subsequent need for surgery for DVD among the 61 children of this series were new findings. Only one of the 61 required subsequent surgery for manifest DVD. In another series of 60 infantile esotropes of similar ages drawn from the same practice who had previously had no inferior oblique surgery, nine needed surgery for DVD. This difference (one of 61 vs nine of 60) was significant.

Variability of strabismus surgery for acquired esotropia.

We developed a mathematical model to predict the probable success rate of the first surgery to correct acquired esotropia with normal accommodative convergence-accommodation ratio in children. A computer-averaged dose-response curve of the effect of 68 bilateral medial rectus recessions was combined with various assumptions regarding likely errors in surgical performance and likely errors in measurement of the preoperative deviation. Fifteen different sets of reasonable assumptions were tested, giving a range of theoretical success rates from 72% to 96%. The results of this study clearly indicate that a certain proportion of failures is to be expected when this or other forms of strabismus are treated surgically by a fully competent ophthalmic surgeon performing as accurately as is practically possible.

Saccadic velocities of horizontal rectus muscles in twenty-five normal humans.

We measured horizontal saccadic velocities for 20 degrees saccades in 25 normal humans. Percent differences for various muscle pairs were calculated for each subject. For example, percent differences of the antagonist muscles averaged +4.9 +/- 10% and percent differences of symmetrical muscles averaged -9.2 +/- 9%. This percent difference type of data, previously unreported, allows more accurate detection of pathology in a given patient than comparison of a single saccadic velocity with an average of normals because of large intersubject variability. We also found ways to make the performance of the test more convenient and the calculations significantly more accurate (0.001). These will be described. The average speed of a horizontal rectus saccade was 396 +/- 53 degrees/sec.