Early diagnosis of compressive optic neuropathy (NOC) in patients with Thyroid Autoimmune Ophthalmopathy (TAO).

Purpose Thyroid Autoimmune Ophthalmopathy (TAO) is a disfiguring and disabling autoimmune disease.Severe ophthalmopathy (3-5% ) may result in compressive optic neuropathy (NOC), with possible sight loss. Aim of this study: the evaluation of early morphological and functional alterations of the optic nerve in TAO patients without clinically evident signs of NOC (i.e. visual acuity defect), by recently available techniques and to correlate the results to the Clinical Activity Score. Methods We examined subclinical optic nerve involvement of 82 eyes in 41 consecutive TAO patients (31 women and 10 men, age 30 to 70 years). All patients have been submitted to: clinical and instrumental evaluation (perimeter computerized, OCT and GDx). Criteria of exclusion: ocular pathologies associated to impairment of visual acuity (patologic myopia, cataract, diabetes, not autoimmune optic neuropathy). Results 19% of the patients did not present perimetral defects, 81% showed a variety of perimetral defects (reduction of the foveal sensitivity, para- pericentral scotomas). Alterations at OCT examination occurred in 65% of the cases, while 50% of the patients presented alterations of the nervous fi ber thickness analized by GDx . These alterations were correlated to the degree of TAO activity. Conclusion Our study indicates that 1) in TAO patients, functional optic nerve alterations occur at an early stage, before any anatomical damage; 2) OCT is more sensitive than GDx analysis for NOC detection.