Benign Paroxysmal Positional Vertigo (BPPV): This condition is common in the elderly and can cause vertigo and imbalance, potentially leading to abnormal gait. Double vision can occur if the vertigo is severe enough to cause nystagmus, which affects vision.

Vestibular Migraine: Although more common in younger populations, vestibular migraines can occur in the elderly and cause vertigo, double vision, and imbalance.
Labyrinthitis: An inner ear infection that can cause vertigo, hearing loss, and imbalance, potentially leading to double vision due to nystagmus.
Cerebellar Ataxia: Conditions affecting the cerebellum can cause ataxia, leading to abnormal gait and potentially vertigo and double vision due to coordination and balance issues.

Posterior Circulation Stroke: A stroke in the posterior circulation can cause vertigo, double vision, and ataxia. Given the patient's age and hypertension, this is a critical diagnosis not to miss.
Brainstem or Cerebellar Hemorrhage: Similar to stroke, a hemorrhage in these areas can present with vertigo, double vision, and ataxia, and is life-threatening.
Multiple Sclerosis: Although less common in new diagnoses at the age of 85, multiple sclerosis can cause a wide range of neurological symptoms, including vertigo, double vision, and ataxia.

Acoustic Neuroma: A benign tumor on the nerve connecting the inner ear to the brain, which can cause vertigo, hearing loss, and imbalance, potentially leading to double vision.
Meniere's Disease: An inner ear disorder that involves vertigo, hearing loss, and tinnitus, which could potentially cause double vision due to severe vertigo episodes.
Superior Canal Dehiscence: A rare condition where there is an abnormal opening in the bone overlying the superior canal of the inner ear, leading to vertigo and imbalance, which might result in double vision.