If a patient cannot read the largest letter on the Snellen Chart, what is the first step to take?

When a patient cannot read the largest letter on the Snellen Chart, the initial and appropriate response is to assess the visual acuity using a different method. Asking the patient to count fingers provides a more qualitative assessment of visual capability when conventional visual acuity testing fails. This method allows the examiner to determine how much the patient can actually see, which is essential for understanding their visual condition.

This step helps to quickly gauge whether the patient has any functional vision and may indicate a need for further assessment or intervention. Other options, while they may improve testing conditions or provide additional information, do not directly assess the patient's ability to perceive visual stimuli as effectively as having them count fingers.

Changing the lighting could help in some cases, but it doesn't directly address the foundational issue of whether the patient can see any form of visual detail. Covering one eye may not yield additional useful information if the patient struggles with vision overall. Trying a different chart could also be an option, but it might not be suitable without first understanding the patient's baseline ability to perceive light or movement. Thus, counting fingers serves as an immediate, practical approach in this scenario.