Ophthalmoplegia is a more severe eye sign in Graves' disease and first affects upward and outward gaze. Later, upward and inward gaze, and lateral, medial and downward gaze, are affected, in that order. Patients complain of double vision, particularly on looking upwards, which they find more unpleasant than normal. The defect in upward gaze is largely due to tethering of the muscles below the globe, particularly to fibrosis of the inferior rectus which may cause the globe to be deviated downwards (Fig. 17.35).
