Surgical modification of the AC/A ratio and the binocular alignment ("Phoria") at distance; its influence on accommodative esotropia: a study of 21 cases.

PURPOSE: To study these changes in patients and their relation to manifestation of accommodative esotropia and response to surgery. METHODS: Patient-subjects: 21 patients who had difficulty adjusting to spectacle correction and underwent bilateral medial rectus loop suspension-recession surgery to alleviate their accommodative esotropia. Measurements of AC/A, uncorrected distance phoria, and related parameters were taken before and after surgical intervention was performed and were analyzed using analysis of variance (ANOVA). RESULTS: Both AC/A ratios and the distance phorias are "statistically significantly" (p< or =0.05), and independently, reduced by this surgical procedure. The manifestation of accommodative esotropia and response to surgery can be fairly accurately predicted from the values of AC/A ratio and distance phoria. CONCLUSION: Surgical treatment of accommodative esotropia creates well defined, long-lasting reductions in the AC/A ratio and the distance phoria.

[Development of the AC/A ratio following surgery of accommodative esotropia]. / Evolution du rapport AC/A après chirurgie de l'ésotropie accommodative.

Whether surgery should be used to correct for accommodative esotropia is still largely debated among strabologists. Fincham's theory (Fincham and Walton, 1957), describing the interaction between accommodation and vergence control systems (accommodative vergence and vergence accommodation), has been extensively studied. Models suggest that weakening of the accommodative vergence should correct esotropia. To test the model proposed by Semmlow (1981), we compared AC/A ratios in esotropic children and age-related normals (orthophoric) and monitored AC/A ratios for immediate (first week) and long term (1-2 months) changes in esotropic children following surgical correction. The AC/A ratio was determined at near and far. The accommodation stimulus was modified using lenses. The slope of the regression line between accommodation stimulus and disparity provided a measurement of AC/A ratio. Preliminary results show a normalisation of AC/A ratio occurring during the first month after surgery, supporting Semmlow's model and validating surgery as a means to correct for accommodative esotropia.

The interactive processes of accommodation and vergence.

A near target generates two different, though related stimuli: image disparity and image blur. Fixation of that near target evokes three motor responses: the so-called oculomotor "near triad". It has long been known that both disparity and blur stimuli are each capable of independently generating all three responses, and a recent theory of near triad control (the Dual Interactive Theory) describes how these stimulus components normally work together in the aid of near vision. However, this theory also indicates that when the system becomes unbalanced, as in high AC/A ratios of some accommodative esotropes, the two components will become antagonistic. In this situation, the interaction between the blur and disparity driven components exaggerates the imbalance created in the vergence motor output. Conversely, there is enhanced restoration when the AC/A ratio is effectively reduced surgically.

[Symptomatologic value of dissociated vertical divergence in concomitant strabismus]. / Valeur séméiologique de la divergence verticale dissociée (D.V.D.) dans le strabisme concomitant.

D.V.D. is an opto-motor anomaly which is likely starting from the retina. D.V.D. is seldom isolated and it is most often found in congenital strabismus or in early onset strabismus (with or without alterared fusion) with an horizontal deviation most often associated with a vertical syndrome. The clinical assessment of D.V.D. is of major importance in the pre and post-operative examination. The simultaneous horizontal and vertical surgery reduces the amplitude of D.V.D by re-establishing a central or peripherical fusion.

[Simultaneous surgical procedures on the horizontal and vertical muscles in the treatment of convergent strabismus]. / Jednoczesna interwencja chirurgiczna na miesniach poziomych i pionowych w leczeniu zezów zbieznych.

In convergent squints the vertical component is very often accompanying the horizontal deviations. This phenomenon is mostly accentuated in congenital squints and in squints very early aquired (onset of squint before the 1st year of life). If after the operation the binocular vision has to be secured indispensable is a surgical procedure which liquidates simultaneously the horizontal as well as the vertical deviation. The operation should be minimally traumatizing; the use of the microscope is most advisable. Preoperative, minute analysis of the motility of the eyes may be performed not earlier than after the child is 2.5 years old. The over mentioned conclusions have been drawn on the basis of analysis of 460 operated cases observed 1 to 5 years.

[Simultaneous horizontal and vertical surgery in esotropia]. / La chirurgie horizontale et verticale simultanée dans les ésotropies.

The vertical syndrome depends on the triple action of the vertical muscles and includes vertical, alphabetical and torsional patterns; this syndrome is of major importance in the diagnosis and treatment of esotropia. We advise routine simultaneous surgery of the horizontal and vertical components. In congenital and early esotropias which occur before one year of age, extensive tests of sensorial evaluation cannot be carried out before three years of age and the vertical syndrome should therefore upon automatically be operated whatever its severity. The advantage of this type of surgery is unquestionable for removal of obstacles preventing recovery of a form of binocular vision. In acquired esotropias when good sensorial conditions (fusion, N.R.C., stereopsis) may be elicited after three years of age and when there is a minor vertical syndrome, vertical surgery might be considered as optional, but as vertical surgery is not dangerous, it can only be regarded as beneficial. With our surgical technique we obtain successful long-term results for horizontal deviation, which improves progressively (83%); vertical and alphabetical patterns improve in similar proportions (65 and 64% respectively). Surgical results depend on which of the following two forms of esotropia is present: in congenital and early esotropias a form of binocular vision with an angle of anomaly occurs almost without exception; in acquired esotropias a form of binocular vision without an angle of anomaly sometimes occurs. Overcorrections require second stage operation, which are simple and nonmutilating when the removal of convex glasses or the use of concave glasses does not reduce secondary exodeviation. Successful results of post-operative fusion confirm the beneficial influence of surgery on the vertical syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)