Refraction testing is the process of measuring how the eye focuses light to determine a prescription for glasses or contact lenses. It identifies short-sight, long-sight, and astigmatism.
How it Works
The test uses lenses of different strengths placed before the eyes while reading letters or symbols on a chart. The examiner refines lens power until the clearest vision is achieved for each eye.
- Can be done manually with a trial frame or phoropter
- Automated instruments provide an initial estimate in many clinics
- Both distance and near focus can be assessed
- Pupil-dilating drops may be used in children or certain cases
Uses
Results guide prescription of spectacles or contact lenses and help assess changes in vision over time. Refraction is also important before many eye procedures and in evaluating unexplained visual symptoms.
- Accurate refraction supports comfortable, clear vision
- Large prescription shifts can signal underlying eye or systemic conditions
- Special techniques are used in children and non-verbal patients
- Refraction findings are interpreted alongside eye health examination
