The eye sensation scale: an ophthalmic pain severity measure

Purpose. The aim was to develop a single-item, categorical ophthalmic pain severity scale. Methods. Focus groups were held with people who had experienced ophthalmic pain. Participants described their ophthalmic pain experiences with reference to level of severity, and commented on proposed pain scale designs. Thematic analysis of transcripts, and participants' category choices and scale preferences, were used to determine the number of response categories and labels chosen for the instrument. The final instrument was evaluated using a mail-out questionnaire. Results. Five ophthalmic pain domains were identified: intensity; nature (including subdomains: physical sensation, temporal patterning, simile/metaphor); physical effects; emotional effects; and behavioral effects. The most frequent descriptors were physical sensation (n = 160), behavioral effects (n = 87), and physical effects (n = 68). Participants preferred a five-category scale. The higher frequency severity descriptors used by the participants formed the basis for the category labels for the instrument ("extreme," "severe," "moderate," "mild," "none"). Notably, many participants rejected the word "pain" in favor of "discomfort" or "light sensitivity." Participants commonly linked severity and nature descriptors; however, the same nature descriptor (e.g., "ache" or "scratching") did not confer the same pain severity between participants. Conclusions. A five-category scale was chosen for assessing the severity of ophthalmic sensations: the Eye Sensation Scale. The scale involves rating the severity of the ophthalmic sensation that is most important to the patient and provides the opportunity to describe other attributes or effects of the sensation. Evaluation indicated the adequacy of the final instrument.