Data on the incidence of GO are limited (11). In a population-based setting in USA, an adjusted rate of 16 cases per per year in women and cases per in men was reported (12). In a recent study of a large cohort of newly diagnosed Graves’ patients, about 75% had no ocular involvement at diagnosis, only 6% had moderate-to-severe GO, and % showed sight-threatening GO due to dysthyroid optic neuropathy (DON) (13) (Figure 1). In a Danish population, moderate-to-severe GO showed an incidence of /million per year (women: ; men: ) (14). Ocular involvement is in most cases bilateral, although often asymmetrical, but it may be unilateral in up to 15% of cases (9). The onset of GO apparently has a bimodal peak in the fifth and seventh decades of life, but eye disease may occur at any age (15). It is more frequent in women, but men tend to have a more severe disease (15-17), as suggested by a decrease in the female/male ratio from in mild GO, to in moderately severe GO, and in severe GO (18). There is a close temporal relationship between the onset of GO and the onset of hyperthyroidism. In approximately 85% of cases GO and hyperthyroidism occur within 18 months of each other (15), although GO may both precede (about 20% of cases) or follow (about 40% of cases) the onset of hyperthyroidism (15).
Negative result does not rule out hypothyroidism, and no assessment of thyroid function Measurement confirms the presence of lymphocytic thyroiditis – but this is not the pathology present in all dogs (some studies suggest 50% of cases), and levels decline with decreased thyroid tissue so is only helpful in early cases. Some breeders are using this as a screening test in young dogs of breeds known to be predisposed to hypothyroidism. In such cases TGAA can be used as a marker of thyroid disease in dogs which are at present clinically healthy.
Eyelid surgery is the most common surgery performed on Graves ophthalmopathy patients. Lid-lengthening surgeries can be done on upper and lower eyelid to correct the patient’s appearance and the ocular surface exposure symptoms. Marginal myotomy of levator palpebrae muscle can reduce the palpebral fissure height by 2–3 mm. When there is a more severe upper lid retraction or exposure keratitis, marginal myotomy of levator palpebrae associated with lateral tarsal canthoplasty is recommended. This procedure can lower the upper eyelid by as much as 8 mm. Other approaches include müllerectomy (resection of the Müller muscle ), eyelid spacer grafts, and recession of the lower eyelid retractors. Blepharoplasty can also be done to debulk the excess fat in the lower eyelid.