Kushner (41) recently stated. “To my knowledge it has never been shown that symmetrical lateral rectus recessions affect the distance deviation more than the near deviation”. Kushner feels that since von Noorden did not subdivide the results for patients who received bilateral rectus recessions into true and simulated DEXT, one cannot directly compare recess-resect procedures in simulated DEXT to bilateral lateral rectus recessions.

Kushner reviewed his cases to see if bilateral lateral rectus recession resulted in a greater decrease in the size of the deviation at distance. He reported that bilateral lateral rectus recessions equally affected distance and near deviation (contradicting Burian’s hypothesis).

Today, many clinicians do not subscribe to Burian’s and von Noorden’s differentiation of true from simulated DEXT for the purpose of determining the type of surgical procedure. Most strabismus surgeons perform bilateral rectus recessions for either true or simulated DE (196). Table III, right, lists the commonly used surgical dosage schedule as suggested by Parks & Mitchell, with common use confirmed by Romano & Wilson in their survey of AAPOS members.

Hardesty (193) and Kushner (41) have pointed out that recess-resect procedures often produce lateral incomitance, but that this is generally of little functional significance. Mitsui (197) in 1980 reported that recess-resect procedures performed on the dominant eye (master eye) gave better results than recess-resect performed on the non-dominant (slave) eye. I lowever, in a subsequent study reported in 1986 by Lennerstrand (198), there was no difference in success when surgery was performed on the dominant versu.s non-dominant eye. Generally, he noted that recess-resect procedures resulted in undercorrections.

Scott et al (199) in 1975 attempted to quantify the specific factors which contribute to the variability of exotropia surgery results. They found the preoperative deviation itself accounted for only 36% of the total variance. The difference between near and distance deviations, age at time of surgery, refractive spherical equivalent, change in deviation in vertical gaze, and the initial preop’ measurement accounted for 94% of the variance.

Table N, next page, provides the formula determined by Scott et al for bilateral

lateral rectus recession.

They also reported that bilateral lateral rectus recessions provided a more stable post-operative condition, i.e., an average postoperative drift of 1.O pd ±1.4 for lateral rectus recessions versu.s an average of 5.O pd ±1.0 for the recess-resect group.

They reported that during the first 6 postoperative weeks there was a substantial shift in the deviation towards Xl’. This stabilized at the 6 week mark and remained fairly stable for their 2 year followup period.

Initial postoperative overcorrections

greater than 15 pd resulted in a 70% alignment within ±9 pd, overcorrection between 4-14 pd resulted in a 81% normal binocular alignment result, while initial postoperative orthophoria resulted in only a 65% normal alignment rate 2 years after surgery. These findings also support the aforementioned desirability of an initial postoperative overcorrection.

7. Exotropia in older patients:

Schlo&sman et al (200) in 1985 evaluated the surgical management of X(T) in

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