What is the purpose of a retinoscope?

A retinoscope is a valuable instrument primarily used to objectively determine the refractive error of the eye. This process involves shining a light into the patient's eye and assessing how the light reflects off the retina. By observing the movement of the light reflex, the practitioner can evaluate the optical properties of the eye and establish whether there is a need for vision correction, such as glasses or contact lenses.

This objective assessment is critical in providing accurate prescriptions, as it helps to eliminate subjective biases that may arise from a patient's verbal feedback about their vision. In contrast, other options involve different types of assessments or measurements that do not pertain to refractive errors. For instance, assessing eye muscle strength, fitting contact lenses, and measuring intraocular pressure are integral to overall eye care but rely on separate methodologies and instruments distinct from the primary function of a retinoscope.