Differential Diagnosis for Bilateral Painless Gradual Vision Loss and Bilateral Optic Neuritis

Single Most Likely Diagnosis

• Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION): This condition is the most common cause of bilateral painless gradual vision loss and bilateral optic neuritis, especially in older adults with a history of vascular risk factors such as coronary artery disease, diabetes, and hypertension. The use of sildenafil may also be a contributing factor, as it can increase the risk of NAION.

Other Likely Diagnoses

• Diabetic Papillopathy: Given the patient's history of diabetes, diabetic papillopathy is a possible cause of bilateral optic disc swelling and vision loss. However, it is less common than NAION.
• Hypertensive Optic Neuropathy: Uncontrolled hypertension can lead to optic neuropathy, which may present with bilateral vision loss and optic neuritis.
• Giant Cell Arteritis (GCA): Although less likely in this case due to the absence of other symptoms such as headache, jaw claudication, or polymyalgia rheumatica, GCA can cause bilateral optic neuritis and vision loss.

Do Not Miss Diagnoses

• Arteritic Anterior Ischemic Optic Neuropathy (AAION) due to Giant Cell Arteritis (GCA): Although the patient's presentation does not strongly suggest GCA, it is crucial to consider this diagnosis due to its potential for rapid progression to blindness and the need for prompt treatment with corticosteroids.
• Optic Neuritis due to Demyelinating Diseases (e.g., Multiple Sclerosis): While less common in older adults, demyelinating diseases can cause optic neuritis and should be considered, especially if there are other neurological symptoms.

Rare Diagnoses

• Leber's Hereditary Optic Neuropathy (LHON): This is a rare mitochondrial inherited disorder that can cause bilateral optic neuritis and vision loss, typically in young adults. However, it is less likely in a 67-year-old male.
• Toxic or Nutritional Optic Neuropathy: Certain toxins or nutritional deficiencies (e.g., vitamin B12 deficiency) can cause bilateral optic neuritis, but these are less common and would require specific exposures or deficiencies to be considered.
• Infiltrative Optic Neuropathy (e.g., due to lymphoma or leukemia): Infiltration of the optic nerve by malignant cells can cause optic neuritis and vision loss, but this is a rare diagnosis that would require specific systemic symptoms or findings.