What is the effect of fogging lenses on a patient during an eye exam?

Fogging lenses during an eye exam serves a specific purpose related to the assessment of a patient’s visual accommodation, which is the ability of the eye to change its focus from distant to near objects. When fogging lenses are introduced, they create a blurred vision effect, requiring the eyes to exert more effort to focus.

This technique effectively limits accommodation by reducing the clarity of the visual stimulus. By imposing this blur, practitioners can better determine a patient's baseline refractive error without the influence of their normal accommodation reflex, which is how the eye adjusts focus depending on distance. The goal is to assess how much correction the patient might need without the complicating factor of their eye's natural ability to adjust focus.

Consequently, the use of fogging lenses is a strategic method to evaluate visual acuity effectively, allowing for a more accurate prescription for corrective lenses, while simultaneously indicating the patient’s accommodation ability.