Which visual symptom can occur in hyperthyroidism?

Which visual symptom can occur in hyperthyroidism?

• A. Eye fatigue
• B. Tremors
• C. Insomnia
• D. Blurred or double vision

Answer: (D)

Graves' disease, the autoimmune form of hyperthyroidism, can involve the eyes. Inflammation and infiltration behind the eye lead to swelling of the extraocular muscles and surrounding tissues, which disrupts coordinated eye movements. This misalignment can cause diplopia (double vision) and, because the eyes don’t focus together properly, can also blur vision. Among the options, blurred or double vision is the visual symptom seen with this eye involvement. Eye fatigue, tremors, and insomnia are common features of hyperthyroidism but are not direct visual symptoms arising from eye muscle dysfunction.