This study is a two-arm crossover study with two subgroups. Subjects will initially be assessed for their headache symptoms (Headache Impact Test (HIT-6) questionnaire) and then are provided an updated refractive prescription and will wear them for 35 ± 5 days. Symptoms will be reassessed after the 35-day control break in. If the subject's symptoms have subsided, they will be exited from the study and will keep their lenses. Provided the subject has symptoms (HIT questionnaire score ≥ 56) after their 35-day use of their updated prescription and they continue to meet the inclusion/exclusion criteria they will proceed to the evaluation portion of the protocol. The first arm receiving neurolens first and the second arm receiving the control first. The control is a single vision or PAL lens which yields the BCDVA and BCNVA of a test subject with no prismatic correction. The neurolens prescribed prism will be based on the practitioner's Rx using the subject's best response to a prism trial lens and must be within a half prism diopter of the neurolens value output of the neurolens Measurement Device and providing the subject's BCDVA and BCNVA. Participants will come back after 35 day wear of their first test lens and the symptom questionnaire is reassessed. They will be now be crossed over to the second pair of study lenses (i.e. subjects in the first arm will not receive control lens and the ones in the second arm will not receive neurolens). Participants will come back after 35 day wear of their second test lens and the symptom questionnaire is reassessed for the final time.
To understand the benefits of the neurolens Measurement Device and neurolens treatment as it pertains to treating symptoms related to Chronic Headaches. It is a Prospective randomized double masked two arm performed on a minimum of 200 to a maximum of 300 subjects identified as symptomatic (HIT-6 questionnaire score equal to or greater than 56) done across 3-15 clinical sites. There are two subgroups: a minimum of 100 in each subgroup (subgroup 1: pre-presbyopic (18-40 years); subgroup 2: presbyopic subjects (41-60 years).