What does LARS stand for?

LARS stands for "Left Add Right Subtract," which is a useful mnemonic in the field of optometry, particularly for determining the adjustments needed for toric lenses when using the astigmatic prescription. When a patient has an astigmatism, the orientation of the cylinder axis becomes crucial for ensuring that the contact lenses provide optimal vision correction.

In practical terms, LARS provides a straightforward method for practitioners to determine how to adjust the axis of a toric lens based on the patient's corneal measurements and the desired visual outcome. When relocating the cylinder axis for a prescription, if you are required to move the axis left, you would 'add' the degree of rotation to the original axis. Conversely, if you move the axis to the right, you would 'subtract' the degree of rotation. This precise calculation is essential for successful lens fitting and providing clear vision.

The other options do not accurately reflect the concept represented by LARS. They either misrepresent the adjustments needed for astigmatism correction or include terms that do not relate to the lens fitting process. Understanding LARS is important for clinicians in order to ensure patients receive the best possible vision correction with their contact lenses.