The root of many contact lens wearing patients’ dry eye symptoms may not be the lenses, but a different underlying etiology entirely, researchers from Berkeley report. While contact lens wear has been an established cause of dry eye, their study found nearly half of symptomatic contact lens wearers had symptoms of dry eye that were not contact lens–induced.

The investigation enrolled 92 participants who completed the Berkeley Dry Eye Flow Chart with and without their lenses. Other testing included ocular surface exams and dry eye questionnaires.

The study divided the subjects into three groups: asymptomatic contact lens wearers; symptomatic contact lens wearers who became asymptomatic after they removed their lenses; and symptomatic lens wearers who did not improve after they stopped wearing their contacts.

The investigators found 40% of subjects were asymptomatic, 33% had contact lens-induced dry eye and 27% had underlying physiological dry eye.

The researchers noted the visual analog scale ratings and ocular surface disease index and standard patient evaluation of eye dryness questionnaire scores were significantly better for the asymptomatic group but did not distinguish contact lens-induced dry eye from physiological dry eye.

Additionally, the study found the physiological dry eye group was significantly worse than both the contact lens-induced dry eye and asymptomatic groups in pre-corneal noninvasive tear break-up time (8.2 seconds in the physiological group vs. 12.3 seconds in the contact-lens induced group and 14.3 seconds in the asymptomatic group), anterior displacement of the line of Marx and superior conjunctival staining.

The asymptomatic and contact lens-induced dry eye groups showed similar clinical signs, whereas the contact lens-induced dry eye and physiological dry eye groups were more similar in reported symptoms, the study noted.

Many contact lens wearers presenting with dryness symptoms have an underlying dry eye condition and won’t respond to treatments aimed at changing lenses or solutions, the researchers said. Contradictory results from research studies of dry eye in contact lens wearers could be due in part to a failure to distinguish subjects with symptoms due specifically to contact lens wear from those whose symptoms have underlying causes unrelated to contact lens wear, they added.

“It is critical for clinicians and researchers both, once a contact lens wearer has presented with symptoms, to investigate further using a combination of questionnaire instruments, clinical assessments and objective measurements to determine the underlying causes or contributing factors, to achieve successful patient treatment and valid, generalizable clinical study results,” the researchers wrote in their paper.