If a consumer states that their old glasses provide better visual acuity than their new glasses with the same prescription, what should the optician check first?

When a consumer reports that their old glasses provide better visual acuity than their new glasses, it is crucial to assess specific fitting parameters that can significantly impact vision. Checking the vertex distance and base curve should be the first step because these measurements can affect the effective power of the lenses the wearer is experiencing.

The vertex distance refers to the distance from the back of the lens to the cornea. If the new frames have a different vertex distance compared to the old glasses, it can lead to a change in the effective lens power the wearer experiences, which can result in blurred vision or reduced clarity.

The base curve of the lens relates to its curvature. If there is a significant difference in the base curves between the old and new lenses, this could lead to changes in how light is refracted through the lens, affecting visual acuity as well.

By checking these parameters first, the optician can determine if the new glasses are fitting properly and if they have been manufactured similarly to the old ones, ensuring the best possible visual outcome for the consumer. If the vertex distance and base curve are confirmed to be correct, other actions such as remaking the lenses or returning to the refractionist can be considered if necessary.