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This 48-year-old man has had "prominent" eyes for the past four years. He has occasional double vision. Visual acuity is 20/20 in each eye with OD plano -0.50 X 40 and OS plano -0.50 X 110 with a +1.75 add. The upper lids appear to be retracted and there is some limitation of ocular movements in both eyes. The forced duction test reveals a “tight” medial and inferior rectus in the right eye and a tight lateral rectus in the left eye.

1.	The most likely diagnosis is:
	d -- thyroid associated ophthalmopathy (Graves disease) This clinical picture is compatible with a diagnosis of thyroid related ophthalmopathy or Graves disease.  It should be recognized that patients with this condition can be hyperthyroid, euthyroid, or hypothyroid, and that the true cause of the pathology may be related to autoimmune disease.  Patients with Graves disease can also have myasthenia, but the signs here are typical of Graves.
2.	The extraocular muscle affected most commonly in this condition is the:
	b -- inferior rectus The inferior rectus is the muscle most commonly involved with enlargement and tightness in Graves disease.  Next most common is the medial, followed by the superior rectus.
3.	The following test(s) can be useful for evaluating optic neuropathy:
	d -- (a), (b), and (c) Enlargement of the extraocular muscles, especially in the posterior orbit, can cause pressure on the optic nerve producing compressive optic neuropathy.  Progression can be monitored by testing visual acuity, red saturation, and visual fields.