How can you verify slab off?

Verifying slab-off involves assessing the alteration in thickness that the lens undergoes to compensate for aniseikonia or differences in visual acuity between the two eyes. A lens clock or lensometer is specifically designed for accurately measuring the curvature and thickness of lenses, which is essential for identifying the slab-off effect.

When using a lensometer, you can observe the power and how it transitions across the lens, specifically looking for that critical change in thickness that indicates a slab-off. This measurement will clearly reveal if the lens is correctly ground to provide the intended optical effect, ensuring that the slab-off has been executed properly to enhance visual comfort for the wearer.

While a visual acuity chart can evaluate how well a patient sees with their lenses, it does not provide the quantitative data needed to assess the physical properties of the lenses. A refractor is used for determining prescriptions rather than verifying existing lenses. A digital camera, though useful for documenting lens conditions or eye examinations, does not measure lens characteristics or modifications directly. Thus, utilizing a lens clock or lensometer is the most effective method for verifying slab-off.