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Long-term effectiveness of optic nerve sheath decompression for pseudotumor cerebri.

OBJECTIVE
To determine the long-term success of optic nerve sheath decompression in preserving visual function in patients with pseudotumor cerebri (PTC).


DESIGN
To define stability of visual fields, we reviewed 32 series of postoperative visual fields in patients who were undergoing optic nerve sheath decompression for PTC who had stable visual acuity and four or more fields during 6 to 60 months of follow-up. The SD of these series was 0.80 dB (+/- 0.39 dB) of mean deviation. Fluctuations within 2 SDs of the 1-month postoperative field were +/- -1.60 dB. We therefore defined stability as a mean deviation within 2 dB of the preoperative visual field; improvement, greater than 2-dB mean deviation, and worsening, less than 2-dB mean deviation. We then extended our review to include all patients (54 patients, 75 eyes) who underwent optic nerve sheath decompression for PTC, who were followed up with serial automated perimetry (Humphrey 30-2).


RESULTS
Fifty-one eyes (68%) showed improvement (36%) or stabilization (32%) of visual function. Twenty-four eyes (32%) experienced deterioration of visual function after an initially successful optic nerve sheath decompression. The probability of failure from 3 to 5 years was .35 by life-table analysis.


CONCLUSION
Optic nerve sheath decompression effectively stabilizes or improves visual function in the majority of patients with PTC and visual loss. However, it may fail at any time after surgery. Patients with PTC need to be followed up routinely with automated perimetry to detect deterioration of visual function.