What is the first step in determining a prescription for glasses?

The first step in determining a prescription for glasses is conducting a visual acuity test. This test measures how well a person can see at various distances, typically using a Snellen chart. The results provide important information about the patient's vision and help identify the level of correction needed for clear sight. By establishing the baseline visual acuity, eye care professionals can then proceed with additional assessments or tests to fine-tune the prescription.

Visual acuity testing is foundational because it directly relates to a person's ability to see clearly, which is the primary purpose of prescribing glasses. Once a baseline is established with visual acuity, other tests, such as eye muscle coordination, color perception, and depth perception, may be performed to evaluate additional aspects of visual function. However, visual acuity serves as the critical first step in the process.