What are eye conditions would require you to be prescribed sunglasses?

Several. Conditions that create severe pain when in bright lights such as uveitis, iritis, forms of ocular albinism, patients who have inflammation after surgery may require sunglasses. Most insurance companies will not accept sunglass prescriptions alone without a note from a doctor.
Visual disturbance. Any condition which affects your vision; whether distance, clarity, focus would warrant a trip to the local ophthalomologist for an eye exam and consultation.