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Volume 1 - Congenital Infantile Esotropia
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Lecture 23 of 24 NEXT»
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Congenital Infantile Esotropia -
Information for Ophthalmologists and Parents
 This outline is intended to provide a comprehensive overview of congenital esotropia answering the questions most frequently asked by both parents and ophthalmologists.
Heredity: There is undoubtedly a multifactorial genetic basis for congenital esotropia. Unaffected parents are more likely to have slightly deficient stereopsis, but do not have OKN asymmetry. Twins are rarely both affected. Siblings are rarely affected with clinically apparent congenital ET. In contrast refractive esotropia is more commonly seen as a family, genetic trait.
Etiology: Congenital esotropia is said to be caused by an inborn defect of the motor fusion mechanism (after Claud Worth). Some adhere to the esotropital theory (Chavasse)
 Incidence:May be as low as 0.27% or 27/10,000 according to Olmstead County MN Study. While seeming low, the recruiting experience of the Pediatric Eye Disease Investigator Group (PEDIG) in the Congenital Esotropia Observation Study (CEOS) lends credibility to low incidence figures.
Early Development of Binocular Vision: A 66% incidence of X(T) was found in study of 4,000 newborns. ET was rarely seen in this study done at Indiana University.
The Milestones for Stable Alignment
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During the 2 to 4 month postnatal period, alignment is achieved in the normal infant and stereopsis can be measured in the laboratory. In cases with deficient motor fusion, esotropia will be seen by 2-4 mos. Many parents report large angle, stable esotropia from birth, but early misalignment constant or intermittent with persistence of ET beyond 2-4 months is required to be sure of the diagnosis of congenital ET. OKN asymmetry present in all infants becomes symmetrical by 6 months in the normal. Patients with congenital ET retain OKN asymmetry. |
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The Characteristics of Congenital Esotropia seem to be Distributed on a Bell Curve
Wide variations occur in presentation, but most congenital ET shows moderate angle esotropia, alternation (or mild preference for fixation of one eye), without DVD, "A" or "V", or oblique "dysfunction" when seen initially under one year.
What does the ophthalmologist see in a patient with congenital esotropia? (Diagnostic criteria)
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* Neurologically normal (except for ET)
* Hyperopia less than +3.50 (A greater hyperopia does not rule out congenital ET)
* Esotropia (10-70PD ± nystagmus) |
A special characteristic of congenital esotropia - OKN asymmetry
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Temporal to Nasal (T/N)
Smooth following, rapid and accurate Refixation |
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Nasal to Temporal (N/T)
Jerky, inaccurate movement with halting refixation |
Congenital eostropia is treated with surgery on the extraocular muscles - timing of surgery depends on surgeon's preference.
Surgical alignment before 18 mos. has been shown to produce better binocularity - will even better binocularity be achieved with alignment before 12 mo. - 6 mo. - 4 mo.? - Results to date are inconclusive. The Pediatric Eye Disease Investigator Group (PEDIG) in the Congenital Esotropia Observation Study (CEOS) determined that ET of 40 diopters or more present at 2 months persists until 7 months and therefore the diagnosis of congenital ET can be made in these cases. ET of less than 40 prism diopters or intermittent ET at 2 mos. has a 50% chance of persisting at 7 mos.
How much surgery for congenital esotropia? (all surgical "numbers" should be modified according to experience)
Bimedial Rectus Recession:
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* Measured from Limbus
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Small
8.5 mm + for ±20PD |
Medium
9.5 mm + to 10.0 mm for 30PD |
Large
10.5 mm + to 11.0 mm for 40+PD |
Measured from Insertion
20 PD - 4mm
30 PD - 5mm
40 PD - 6mm
50+ PD - 7mm |
* A reason for limbal measurement is that the medial rectus insertion site is variable while axial length and corneal diameter are consistent for age. A few surgeons prefer to operate on 3 or 4 muscles for larger angles and some prefer recession recess/resect one eye. The medial rectus insertion site is not related to the angle of strabismus. |
Results of Surgery for Congenital Esotropia:
85% of patients are aligned initially with one surgery with limbal measurement formula.
Need for Reoperation (With long term followup 10 years)
25%: none 50%: one 25%: more than one
Overall:An average of 2.1 operations is done per patient with congenital esotropia
What can happen in the course of treatment of congenital esotropia?
1. Corrected with first surgery and stays that way.
2. Initial Undercorrection - needs re-BMR or L.R. resect.
3. Initial Overcorrection - needs advance/resect MR or recess LR.
4. Initially OK, but goes from:
OK(R)Recurrent ET
OK(R)Secondary XT
OK(R)"OAIO" - "V" or "OASO" - "A"
OK(R)DVD/DHD - All Forms (some with "OAIO")
OK(R)Accom. Component - Rx Hyperopia
5. "OK" after first reoperation but needs second reop surgery:
"OK"(R)Late XT
"OK"(R)"V" or "A"
"OK"(R)More DVD/DHD
"OK"(R)Late ET
A few cases of congenital ET need even more surgery (3-4+).
Longer term follow-up :
The tendency for "new strabismus problems" seems to wear out as the patient reaches mid teens, but patients with congenital esotropia and their families should expect two surgeries per patient on average.
Long term percentage results with optimal treatment can be expected as follows:
* Gross Stereo: in 40% of children with "early surgery"
* OKN asymmetry: 100% - pathognomonic
* DVD/DHD: 90% in some form including just a trace of deviation
* Nystagmus - latent or manifest latent: 50% +
* Satisfactory alignment/appearance with stability is the rule with careful followup and necessary re-treatment - approaches 100% by mid teens (usually earlier)
Summary - Congenital- Infantile Esotropia:
Children with congenital esotropia have a missing or deficient motor fusion mechanism. This "opens the loop" somewhere in the central nervous system - possibly at the occipital cortex where vision first meets for a complete picture. The opening of the loop sends a deficient message downstream to the brain stem. The "default" is for the eyes to cross. After all, that is what they do best. Later, DVD and nystagmus occur. Since normal binocularity is never achieved, OKN asymmetry persists.* These patients with congenital ET are not normal and cannot be made normal by surgery - only better. Early surgery may be required for best results but "early surgery" has yet to be satisfactorily defined. The final results of treatment of congenital esotropia may depend, at least in part, on the degree of initial insult. vonNoorden has stated that the best results attainable after treatment of congenital esotropia is subnormal binocular vision. It is becoming clear that all patients with congenital esotropia (congenital motor fusion deficit) are not the same. There is a broad spectrum of severity. Good luck. (* or the other way around.)
The Strabismus Minute, Vol. 1, No. 5 Copyright © Eugene M. Helveston All Rights Reserved
Editor-in-Chief: Eugene M. Helveston, M.D.
Associate Editor: Faruk H. Orge, M.D.
Editorial Board: Bradley C. Black, M.D.
Edward R. O'Malley, M.D.
David A. Plager, M.D.
Derek T. Sprunger, M.D.
Daniel E. Neely, M.D.
Naval Sondhi, M.D.
Senior Editorial Consultant: Gunter K. vonNoorden, M.D.
Graphics: Michelle L. Harmon
Technical Support: George J. Sheplock, M.D.
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