Methanol Toxicity: The patient's acute onset of vision problems, particularly with no improvement on pinhole testing, combined with a history of excessive alcohol consumption (as indicated by being quite drunk and vomiting), points towards methanol toxicity. Methanol can cause visual disturbances, including blurred vision, and the fact that the vision does not improve with pinhole testing suggests a problem beyond simple refractive error.

Ethanol Toxicity: While ethanol itself does not typically cause permanent vision loss, acute intoxication can lead to transient visual disturbances. However, the severity of vision problems described, especially without improvement on pinhole testing, makes this less likely as the primary cause.
Head Trauma: Given the patient's intoxicated state, there's a possibility of head trauma, which could lead to vision problems. However, the bilateral nature of the vision loss without other signs of trauma makes this less likely.
Acute Angle-Closure Glaucoma: This condition can cause sudden vision loss, but it typically presents with severe eye pain, redness, and often nausea and vomiting, which are not all explicitly mentioned here.

Carbon Monoxide Poisoning: Although less directly related to the symptoms of vision loss, the patient's rapid shallow breathing and altered mental status (intoxication) could also suggest carbon monoxide poisoning, especially if the alcohol consumption occurred in an enclosed space with improper ventilation.
Stroke or Cerebrovascular Accident: Any sudden neurological symptom, including vision loss, should prompt consideration of a stroke. The patient's age and lack of other risk factors make this less likely, but it's a diagnosis that could have severe consequences if missed.

Optic Neuritis: An inflammatory condition of the optic nerve that can cause sudden vision loss, but it's typically unilateral and might be associated with pain on eye movement.
Papilledema: Increased intracranial pressure can cause bilateral vision disturbances, but it would typically be associated with other signs such as headache, and the vision loss might not be as sudden.
Toxic or Nutritional Optic Neuropathy: Certain toxins or nutritional deficiencies can cause optic neuropathy, leading to vision loss. However, these conditions are less common and would likely have a more gradual onset.