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Query: UMLS:C0038379 (strabismus)
 9,317 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This paper reviews the current status of our computer model for the management of strabismus and its future direction. Vector analysis was first used in the 1950s for the assessment of strabismus. Robinson's model was the first computer simulation of ocular motility. Using physiological principles and anatomical approximations, Robinson's model sought to predict the strabismic pattern to be expected from a given injury. The Kault/Stark 'reverse' model works in the opposite direction, to first simulate the given strabismic pattern and then advise the surgery required to restore orthophoria. The surgeon is able to 'trial' various operations and compare the expected postoperative results. An automated system is currently being developed to ease the difficulty in measuring the position of the eyes in all nine positions of gaze. This paper includes three illustrative case reports.
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PMID:Moving muscles with microchips, mathematics and models: an update on the 'reverse' model. 178 75

In recess-resect surgery, the dosage depends on the preoperative angle of squint and on the ratio between squint-angle reduction and dosage that the surgeon has found in previous surgery. Recommendations pertaining to this ratio vary widely among authors. Some say a recession does more than a resection, while others believe the opposite is true. Finally, most find a lower ratio at smaller preoperative angles of squint. We investigated the matter, using our modified version of the Robinson computer model of eye movements. We calculated the amounts of surgery needed to reduce 10, 15, 20, 25, and 30 degree angles of squint to zero. The increase of the ratio at large angles of squint was indeed predicted by the model. The decrease at small angles of squint, however, was not predicted by the model. We found it impossible to model the decrease of the ratio at small preoperative angles of squint. The ratios for recess and resect surgery were approximately similar. We present an inventory of the possible causes of the discrepancies. In addition, we calculated the effects of Faden surgery and found that the predictions of the computer model correspond closely to reality.
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PMID:Analysis of the dosage controversy in recess-resect and Faden surgery with the Robinson computer model of eye movements. 344 49

While, in routine strabismus surgery, empirical guidelines and experience are the best in judging which eye muscles to operate, a complex case may need a unique surgical approach, the consequences of which cannot always be envisioned in detail. We sought to improve the results of surgery in these cases by preoperative simulation of each case with the Computerized Strabismus Model 1.0 (CSM). The basis of this model was laid by David A. Robinson. It has been improved by us over the past years to the point that it can be used clinically. Improvements concerned, for example, the mechanics of the eye muscles and the anatomy of insertions and origins. The ease of operation has been improved and the algorithms have been made so much faster that a full calculation for 9 positions of gaze now takes 10 seconds on a hand-held Hewlett Packard 200LX Palmtop. From 1994 onwards, all cases to be operated in our department which were more complex than straightforward horizontal rectus muscle surgery were simulated in the model preoperatively. The predictions of the model compared well with the actual result of surgery in most cases. The model was particularly good in handling complex and unique disorders of motility. However, the model could not reliably predict the effect of strabismus surgery in cases with mechanical restrictions of motility.
Strabismus 1997
PMID:Sixty strabismus cases operated with the Computerized Strabismus Model 1.0: When does it benefit, when not ? 2131 73

In this article we review our further development of D.A. Robinson's computerized strabismus model. First, an extensive literature study has been carried out to get more accurate data on the anatomy of the average eye and the eye muscles, and about how these vary with age and with refraction. Secondly, the force-length relations that represent the mechanical characteristics of the eye muscles in the model have been determined more accurately in vivo recently, and the model was changed accordingly. Thirdly, many parameters that were free in the original model and not derived from in vivo measurements were replaced by derivatives from in vivo measurements or made redundant. Fourthly, the ease of operation was improved greatly and the algorithms were made so much faster that a calculation for nine positions of gaze now takes ten seconds on a handheld HP 200LX Palmtop. The predictions of the model compared well with clinical results in horizontal muscle surgery, oblique muscle surgery, forced duction tests and abducens, oculomotor or trochlear palsies. Consequently, complex strabismus surgery in our clinic is now guided by the predictions of the computerized model.
Strabismus 1996
PMID:Robinson's Computerized Strabismus Model Comes of Age. 2131 16