 |
 |
26 |
 |
|
Another, very recent most comprehensive review and re-review of many previously published reports of treatments for
X(T),
including surgery, was recently published by optometrists Coffey et al (218) (1992). They reviewed 59 studies of X(T) treatment, including again most of those studied by Flax and Selenow. They compiled pooled success rates.
Based upon the stated criteria of success for each study they calculated the following pooled success rates: 28% for over minus therapy
(N=215);
28% for prism therapy (N=201), 37% for occlusion; 46% for surgery (N=2530); and 59% for optometric orthoptic/vision therapy.
Functional
success for surgery was 43%, while
cosmetic
alignmnent
success was 61%. Due to the addition of several more recent and more successful surgical reports, these rates are better than those determined by Flax and Selenow (34%/61%).
The best rate of functional success, 59%, was achieved by optometric orthoptic “vision therapy”. This rate of functional success appears to be 37% greater than the 43% achieved by eye muscle surgery.
However, all of the objections and problems with such direct comparison noted above in the discussion of the work of Flax and Selenow also are valid for this work of Coffey et aL
The techniques described as “orthoptic vision therapy” in the Coffey study are the same which we have described in the earlier parts of this paper, designed to facilitate increased vergence control and enhanced sensory fusion.
The authors acknowledged that pooled data must be viewed carefully in light of the fact that each study pooled suffers from numerous scientific flaws, e.g., small sample size, experimenter bias, inadequately defined treatment and success criteria, and the virtual absence of statistical analyses.
C. Recommended Therapy
As we have noted above, it is inappropriate scientifically, in addition to being just terribly difficult practically, considering the information available in the scientific literature, to realistically compare orthoptics and eye muscle surgery treatment of X(T) since the procedures, population, and criteria of success are so variable amongst various eye health care professionals.
Moreover, most of the studies evaluating orthoptics or surgery are retrospective and have few, if any, controls for placebo effect, or experimental bias. Most studies which report changes of symptoms after
|
Major Review: Intermittent Exotropia; Basic and Divergence
Excess
Type
therapy did not use scaled questionnaires. Also, methods of evaluating intermittency are questionable or nonexistent.
Comparison across studies is difficult since populations vary. Also, specific surgical and orthoptic techniques vary with the eye health care professional.
It would be valuable to have a large scale prospective clinical trial to determine scientifically the best treatments for DEX(T). This review, if nothing else, would underline this need.
It is our impression that X(T) under the age of six years should be treated cautiously so as to reduce or eliminate the possibility of developing amblyopia or permanent loss of stereopsis.
• Patching, to eliminate or alter supppression patterns should be done with caution, since patching might change a small angle X(T) into a large angle XT
• Minus lens therapy might be initiated with or without prisms to eliminate any evidence of deviation.
• A red lens and TV trainer could be used 1-2 hours a day in an attempt to eliminate the suppression scotoma.
If the deviation persists or increases, surgical intervention should be considered.
In children over six years, some professionals believe that orthoptics or vision training should be instituted if the deviation is not too large. Large deviations, however, may be initially treated with surgery unless the patient or parents or the eye care professional want to try nonsurgical means first.
An orthoptic approach suggested and used by the first author includes office based therapy and home therapy using the following modalities: red lens techniques, minus lenses, prisms, stereoscopic targets in space to initiate alignment and stereoscopic appreciation. Stereoscopic detail is then slowly faded out until only flat fusion targets remain. Alignment is then reinforced while viewing non-fusable targets, e.g., simultaneous perception targets.
If no improvement or deterioration is seen within a reasonable period, surgery should be considered. The specific surgical procedure remains the choice of the surgeon since no specific advantage has been shown to accrue to any specific technique, although bilateral lateral rectus recessions seem to be almost universally the first procedure for most North American eye muscle surgeons. An attempt to surgically create a moderate early postoperative esodeviation of 10 pd should made, if possible, in the young.
|
Summer
of
1993
Adults and children over 12 years of age may be treated similarly. Generally, if presented with a large deviation, surgery to reduce the strabismus (conservative so as not to create an esodeviation postoperatively in this group) followed by orthoptics is usually rewarding.
If there are any cases with clear indications for one choice of therapy over another, it would seem that very large exodeviations in infants and toddlers would be good candidates for primary surgical treatment because orthoptic therapy is not applicable or practical or very successful in such cases because of both the size of the deviation and limited cooperation available from preverbal children. (But see also aforementioned hazards to binocularity).
Conversley, older children and adults, in whom orthoptic measures can be used, especially those with smaller deviations more readily controllable by feedback, patching, lenses or prisms, would seem the best candidates for primary non-surgical treatment.
Between these examples, active and passive orthoptics and surgery can be justified, individually or together.
We have reviewed both divergence excess and basic exotropia which have similar sensory motor characteristics.
Treatment modalities include minus lenses, prisms, orthoptics, and/or surgery. Each therapeutic regimen has its proponents. To date no uniformly accepted treatment plan has been acceptable to all of the eye care professional community who treat these problems. The lack of agreement among professionals as to the proper treatment suggests the difficulty in creating a permanent perfect cure.
Lastly, we agree with Baker (217), who suggests that future treatment of exotropia “must consider that the control center for ocular motility is located in the theoretical black box”. Treatment of the strabismus must be aimed not only at controlling the sensory motor components, but also their
exotropia, basic
exotropia, divergence excess exotropia, intermittent
prism adaptation review, major
surgery, strabismus
vergence after effects
|
|
212
|
|
|
26 |
|