Reduced tear meniscus dynamics in dry eye patients with aqueous tear deficiency

Abstract

Purpose: To measure the tear meniscus dynamics in aqueous tear deficiency dry eye patients using optical coherence tomography.

Design: Clinical research study of a laboratory technique.

Methods: Twenty-five aqueous tear deficiency dry eye patients and 30 healthy subjects were recruited. Upper and lower tear menisci of 1 randomly selected eye of each participant were imaged during normal and delayed blinking using optical coherence tomography. Measured parameters included upper tear meniscus height and volume, lower tear meniscus height and volume, the blink outcome defined as the meniscus volume change during blink action, and open eye outcome defined as the meniscus volume change during the open eye period.

Results: During normal blinking, both tear meniscus height and volume before blink in dry eye patients were significantly smaller than those in healthy subjects, except for the upper tear meniscus volume. During normal blinking, the blink outcome and open eye outcome of lower tear meniscus were significantly smaller in dry eye patients compared with healthy subjects. During delayed blinking, the upper and lower tear menisci heights and volumes significantly increased in both groups. However, dry eye patients had smaller increases than healthy subjects. During delayed blinking, the open eye outcomes of upper and lower tear menisci were smaller in dry eye patients than healthy subjects.

Conclusions: Dry eye patients seem to have reduced tear meniscus dynamics during normal blinking and smaller increases of meniscus volume during delayed blinking. Analysis of tear meniscus dynamics may provide more insight in the altered tear system in dry eye patients.

Figure 1. A diagram of the instruction for measuring tear meniscus variables during blinking

Two consecutive blink actions were recorded by OCT during both normal and delayed blinking. The frames acquired immediately before (checkpoint A, C) and after (checkpoint B, D) each blink action were processed to yield tear meniscus variables. The mean values of checkpoint A and C were defined as the tear meniscus variables before blink. Similarly, the mean values of checkpoint B and D were defined as the tear meniscus variables after blink. The tear meniscus variables at the beginning and the end of the open eye period were obtained from checkpoint B (after first blink) and checkpoint C (before second blink), respectively.

Figure 2. Upper and lower tear menisci in a dry eye patient and a control subject imaged immediately before normal and delayed blinks

The images obtained from a dry eye patient (Far left, Middle left) and a control subject (Middle right, Far right) were demonstrated. Compared to normal blinking (Far left, Middle right), both upper and lower tear menisci were swollen with delayed blinking (Middle left, Far right). The tear menisci in the dry eye patient (Far left, Middle left) appeared smaller than those in the control subject (Middle right, Far right). CO, cornea; UTM: upper tear meniscus; LTM: lower tear meniscus; UL, upper eyelid; LL lower eyelid. Bars = 500 µm.

Figure 3. Tear meniscus height and volume during normal and delayed blinking in dry eye patients and control subjects

Both upper and lower tear menisci heights (Top right) and volumes (Bottom right) during delayed blinking were significantly larger than those during normal blinking (Top left, Bottom left) in both dry eye patients and controls (P < .05). The asterisks (*) indicate the tear meniscus variables in dry eye patients were significantly smaller than those in controls (P < .05). UTM, upper tear meniscus; LTM, lower tear meniscus; TMH: tear meniscus height; TMV: tear meniscus volume.

Figure 4. Blink outcome and open eye outcome of tear meniscus volume during normal and delayed blinking in dry eye patients and control subjects

During normal blinking, dry eye patients had smaller blink outcome and open eye outcome of lower tear meniscus volume during normal blinking (Middle right). Furthermore, open eye outcomes of both tear menisci in dry eye patients were smaller during delayed blinking compared to controls (Middle left, Far right). The asterisks (*) indicate the outcomes in dry eye patients were significantly smaller than those in controls (P < .05). Vertical bars denote 95% confidence intervals. UTMV: upper tear meniscus volume; LTMV: lower tear meniscus volume.