Assessing Tear Secretory Response in Health and Disease Using a Novel i-Onion Device.

Abstract

Purpose: To evaluate tear secretory response using a novel device, the i-Onion, which stimulates lacrimal gland activity with concentrated CO 2 bursts.

Methods: The i-Onion device delivers a controlled CO 2 burst to the ocular surface, stimulating the lacrimal gland's tear production response. We studied 120 participants: 40 with glaucoma, 40 with cataracts (some followed postsurgery), and 40 controls. Basal tear volume (BTV) was measured using a 3-min unanesthetized the Schirmer test. Stimulated tear volume was then recorded over another 3 min after a 3-second i-Onion stimulus. Tear reserve volume (TRV), the study's primary outcome, was calculated as the difference between stimulated tear volume and BTV.

Results: Participants' mean age was 60.5 years; 78% male, 59% White. No significant differences in TRV were found among the groups (glaucoma: 9.3 mm; cataract: 8.3 mm; control: 7.9 mm, P =0.67) but BTV was significantly lower in patients with glaucoma and cataract compared with controls (glaucoma: 13.6 mm; cataract: 14.1 mm; control: 19.0 mm, P =0.03). Basal tear volume also decreased with age (r=-0.2, P =0.01). Presurgical TRV in patients with cataract showed a nonsignificant negative correlation with postsurgical ocular symptoms (r=-0.23, P =0.2).

Conclusion: The i-Onion device demonstrated that TRV was preserved in elderly individuals with glaucoma and cataract, despite decreased BTV with age and disease.