Which statement correctly refers to the letters on the Snellen chart?

The statement that some letters are easier to recognize than others despite equal arc subtending highlights a key aspect of visual perception. Each letter on the Snellen chart may be designed to subtend a similar visual angle at a set distance, but their recognizability is influenced by factors such as shape familiarity and complexity.

For instance, letters like "E" or "O" may be easier for an individual to identify than letters that contain more intricate shapes or are less common in the language, such as "X" or "Z." This means that, even though the letters may cover the same angular measurement, the brain processes some letters more quickly and accurately due to their structural simplicity or familiarity.

Thus, this statement accurately reflects the complexities of human visual perception and letter recognition, making it the correct choice regarding the performance and challenges individuals may face while using a Snellen chart for vision assessment.