Orbital decompression

Superior limbic keratoconjunctivitis is associated with thyroid dysfimction and appears to be a prognostic marker for severe Graves ophthalmopathy. Approximately one-half of patients with superior limbic keratoconjunctivitis have eyelid retraction and one-half have eyelid lag. Whether eyelid retraction is causative or merely associated is unclear. Several patients exhibited resolution of the superior limbic keratoconjunctivitis after eyelid retraction surgery or orbital decompression. 

Orbital decompression should be considered for patients with severe class 5 disease for whom steroids, orbital radiation, and other medical therapies have proven to be ineffective or contraindicated. This might include patients whose compliance may be poor or for whom follow-up may be difficult. 

Figure 32-12 Approaches for orbital decompression. (Modified from Char DH. Thyroid eye disease, ed. 2. New York Churchill Livingstone, 1990.)...

Because of the inherent snrgical risks involved, orbital decompression should be considered only after more conservative therapentic measnres have been attempted. Orbital decompression snrgery does not affect the course of the inflammatory or fibrotic components of thyroid ophthalmopathy. Therefiare orbital decompression should not be considered until the thyroid state is stable. 

Orbital decompression is useful in nearly all patients with compressive optic neuropathy.The relief of pressure... 

Disfiguring proptosis Orbital decompression Eyehd surgery... 

Graves ophthalmopathy severe enough to warrant high-dose steroids, orbital radiotherapy, or orbital decompression is estimated to occur in not more than 20% of patients with Graves disease. In most cases the disorder can be managed adequately with more conservative therapeutic measures. In most patients minor interventions that are required mainly include treatment of exposure keratopathy. Table 32-4 summarizes the current therapeutic approaches to the patient with Graves ophthalmopathy. 

Antoszyk JH, Tucker N, Codere E Orbital decompression for Graves disease exposure through a modified blepharoplasty incision. Ophthalmic Surg 1992 23 516-521. 

Lyons CJ, Rootman J. Orbital decompression for disfiguring exophthalmos in thyroid orbitopathy. Ophthalmology 1994 101 223. 

Retrobulbar hemorrhages During the administration of botulinum toxin type A for the treatment of strabismus, retrobulbar hemorrhages sufficient to compromise retinal circulation have occurred from needle penetrations into the orbit. It is recommended that appropriate instruments to decompress the orbit be accessible. Ocular (globe) penetrations by needles have also occurred. An ophthalmoscope to diagnose this condition should be available. Inducing paralysis in 1 or more extraocular P.788... 

If steroid therapy fails or is contraindicated, irradiation of the posterior orbit, using well-collimated high-energy x-ray therapy, will frequently result in marked improvement of the acute process. Threatened loss of vision is an indication for surgical decompression of the orbit. Eyelid or eye muscle surgery may be necessary to correct residual problems after the acute process has subsided. 

Recent CT and MRI studies showed that increased extraocular muscle volume correlates with compressive optic neuropathy as well. Although some patients show inflammation of the nerve and sheath, it has been postulated that these patients have shallow orbits or that they lack the ability to decompress anteriorly. Patients at greater risk of developing optic neuropathy are older patients with enlarged extraocular muscles and limited motility. Diabetic patients with proptosis and extraocular muscle enlargement are also more likely to develop optic neuropathy. 

Recent advances inclnde the nse of a fornical incision, which is considered a technical advance in decompression surgery because it allows good views of the medial and lateral walls of the orbit. Additionally, a transcaruncu-lar approach to the medial wall allows easy removal of the ethmoid bones. 

Most of the time, the addition is predominantly endo that is, the more bulky side of the alkene is under the ring, and this is probably true for open-chain dienes also. However, exceptions are known, and in many cases mixtures of exo and endo addition products are found. ° ° An imidazolidone catalyst was used to give a 1 1.3 mixture favoring the exo isomer in a reaction of conjugated aldehydes and cyclopentadiene. It has been argued that facial selectivity is not due to torsional angle decompression. Secondary orbital interactions. ° have been invoked, but this approach has been called into question. ° " There has been a direct evaluation of such interactions, however. The endo/exo ratio can be influenced by the nature of the solvent. ... 

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