Visual neuropraxia and progressive vision loss from thyroid-associated stretch optic neuropathy.

PURPOSE: Animal models have provided information on the tensile strength of the optic nerve, but to our knowledge no in vivo study of the tensile strength of the human optic nerve has been reported. Accordingly, we present 3 cases of stretch optic neuropathy, an often unrecognized cause of vision loss from thyroid eye disease.
METHODS: Observational study of thyroid-associated stretch optic neuropathy.
RESULTS: Three cases of stretch optic neuropathy were identified. Visual acuity was better than 20/40. Two patients had arcuate scotoma. Moderate to severe proptosis of 25 to 33 mm was present, without evidence of apical orbital compression. Two patients had retinal hemorrhages suggesting venous stasis retinopathy; the venous stasis retinopathy resolved after orbital decompression. Orbital decompression resulted in improvement of visual function. The rate of decibel sensitivity loss on automated perimetry was estimated at -0.042 dB/da in one case, with complete blindness projected to occur within 785 days from the onset of visual symptoms.
CONCLUSIONS: Stretch optic neuropathy presents initially as neuropraxia with temporary visual loss. Orbital decompression should be considered for treatment before permanent and irreversible visual loss ensues.