Which of the following is not part of the anatomic measurements collected in the pre-fit GP lens examination?

• A. Eyelash length
• B. HVID
• C. Pupil diameter
• D. Palpebral aperture height/lid position

Answer: (C)

In GP lens fitting, you gather measurements that affect how the lens sits on the cornea and how the eyelids interact with the edge. Eyelash length is noted because longer lashes can contact the lens edge or influence tear film distribution and movement. HVID—the horizontal visible iris diameter—helps gauge overall eye size and informs lens diameter choices. Palpebral aperture height and lid position describe how much the eyelids open and how they ride over the lens during blinking, which influences edge clearance and centration. Pupil diameter, on the other hand, varies with lighting and isn’t a fixed anatomical parameter used to determine the initial GP lens size or fit. It’s more relevant for optical design considerations in certain multifocal schemes than for the baseline pre-fit anatomy. So pupil diameter isn’t part of the standard pre-fit anatomic measurements.