What is the recommended lighting condition for testing with the Snellen chart?

The recommended lighting condition for testing with the Snellen chart is illuminated with white light. This optimal lighting is crucial because adequate illumination helps ensure that the letters on the chart are clearly visible and that the test can accurately assess an individual's visual acuity. White light provides a balanced illumination that makes it easier for the eye to distinguish between the different letters and their corresponding sizes.

Insufficient lighting, like dim light or no lighting, would hinder the ability to see the chart clearly, potentially leading to inaccurate results. Similarly, using a colored light source can alter the perception of color and contrast, making it difficult to assess visual acuity properly, as it could obscure the letters' clarity. Proper white light is essential for maintaining consistent test conditions, thereby providing reliable outcomes in visual acuity assessments.