[The thickness of the retrobulbar portion of the optic nerve in Graves ophthalmopathy measured by ultrasound].

INTRODUCTION

The clinical diagnostic of Graves ophthalmopathy is based on the association of ocular signs and the disease of the thyroid gland. The evolution of the disease involves the development of eye globe protrusion, extraocular muscle thickening pressuring the optic nerve, which can result in its thickness.

OBJECTIVE

The aim of the paper is to find whether the retrobulbar optic nerve thickened and if there was a correlation between its possible thickening and the thickness of the muscles in Graves ophthalmopathy. We also wished to test the theory of compressive aetiology of such thickening using a 30-degree test.

METHODS

We examined 28 patients with Graves ophthalmopathy. The thickness of the retrobulbar optic nerve was measured by ultrasound on a B-scan using the Schraeder's method and by the largest thickness of the internal muscle.

RESULTS

The thickness of the retrobulbar portion of the optic nerve in the 52 analyzed eyes with signs of the disease ranged between 3.24 mm to 6.30 mm, with median of 5.13 mm, indicating that the majority of the patients had optic nerve thickening rating at this value. Forty-eight eyes had a marked retrobulbar optic nerve thickening, with the thickening over 4 mm, while in 4 eyes with signs of Graves ophthalmopathy the thickness of the optic nerve was within normal limits. We detected that 92.3% of the patients with muscular thickening also had a directly proportional thickening of the retrobulbar optic nerve. By using the 30-degree test we confirmed the diagnosis of compressive neuropathy.

CONCLUSION

Patients with Graves ophthalmopathy and thickened muscles, also have a thickening of the retrobulbar optic nerve; the rate of the thickness directly depends on the degree of the muscular thickness. The word is of compressive neuropathy, i.e. the thickness of the optic nerve is the result of subarachnoid fluid stasis caused by the compression on the optic nerve.