What is the first aid step for treating snowblindness?

Covering the eyes with a dark cloth is the appropriate first aid step for treating snowblindness, which is an ocular condition caused by excessive exposure to sunlight reflecting off snow and ice. This exposure can lead to temporary vision impairment and discomfort due to damage to the cornea.

By covering the eyes with a dark cloth, you help reduce light exposure and alleviate discomfort, allowing the eyes to rest and heal. This action is vital since the eyes are sensitive after experiencing snowblindness, and shielding them from further light can prevent additional irritation or damage.

The other options do not effectively treat snowblindness. Applying ointment might not address the immediate need for reducing light exposure and could lead to further irritation. Exposing the eyes to light would exacerbate the condition rather than help. Flushing with water may be applicable in cases of chemical exposure to the eyes but does not specifically respond to the superficial eye damage from snowblindness.