Investigation of extended blinks and interblink intervals in subjects with and without dry eye

Abstract

BackgroundThe purpose of this study was to investigate the occurrence and duration of extended blinks ≥ 70 msec and their associated interblink intervals in normal subjects and in subjects with mild to moderate dry eye.MethodsThis single-center, prospective, double-blind study included 11 subjects with dry eye and eight subjects with normal eyes. Extended blinks were defined as lid closure in at least two successive video frames (≥70 msec). Digital video imaging of each subject’s eyes was recorded while the subject viewed a 10-minute documentary. The subjects did not know that blink was the outcome being measured. Following capture, the videos were manually analyzed in a masked fashion for the occurrence of extended blinks. The length of the interblink interval (ie, time between blinks) before and after these extended blinks (the interblink interval ratio) was calculated, as well as differences in lid contact times.ResultsThe dry eye group had a median extended blink duration which was 2.53 times longer than that of the normal group. For subjects with dry eye, interblink intervals post-extended blink were significantly longer than interblink intervals pre-extended blink (P < 0.001). Interblink intervals did not lengthen significantly in normal subjects. In both groups, the duration of the extended blink was significantly (P = 0.001) and positively correlated with interblink interval ratio (post-extended to pre-extended blink interblink interval), such that for each doubling of extended blink duration, the interblink interval ratio increased by 10%. Blinks longer than one second in duration occurred almost exclusively in subjects with dry eye.ConclusionThis study reports three central findings: blink duration tended to be longer in subjects with dry eye; a lengthening of the interblink interval after an extended blink occurred in subjects with dry eye but not in those without dry eye; and a longer blink duration was associated with a significantly increased interblink interval ratio in all subjects.

Blink patterns and lid-contact times in dry-eye and normal subjects

“…In previous exploratory studies, we focused first on blink rates, or their reciprocal, IBIs, and the ability to use statistical characteristics of these time-series data to differentiate dry-eye and normal subjects 16. We then began exploring the duration of blinks, finding that abnormally long lid closures appear to occur with greater frequency in dry-eye subjects, and that the IBIs surrounding these long lid closures are modified only in dry-eye subjects 17. We turned our attention in this study to a complete categorization of blinks into their six types: three partial types (25%, 50%, and 75%), all full blinks with complete lid closure, all full extended blinks with greater than 0.1 second lid closure, and superextended blinks of greater than 0.5 second in duration, distilling into ever-narrowing categories the average total time the subjects’ eyes were closed.…”

Eye blink detection based on motion vectors analysis

“…Mostly due to dry eye syndrome, only partially closed eye blink often occurs and this is called an incomplete blink [10]. Extended blinks [11] are the opposite when the eye closure (fully closed eye) lasts from 70 ms to around 1 second. Some people blink multiple times in a sequence; for example double blinks or even quadruple blinks can occur.…”

An evaluation of Retaine&trade; ophthalmic emulsion in the management of tear film stability and ocular surface staining in patients diagnosed with dry eye

“…For the assessment of signs and symptoms, various calibrated scales were used throughout the study by the investigators and the subjects. Investigators graded fluorescein staining and lissamine green staining in each eye with the Ora Calibra™ Corneal and Conjunctival Staining Scale 9 – 12 (Ora Calibra, Andover, MA, USA), (0–4 scale with 0.5 increments) on which 0 is no staining and 4 is severe staining. This scale divides each eye into five staining areas: the inferior, superior, and central regions relative to the cornea and the temporal and nasal regions relative to the conjunctiva.…”

“…Investigators graded lid margin redness in each eye by using the Ora Calibra™ Lid Margin Redness Scale, 12 a 4-point scale (0–3) on which 0 is none and 3 is severe. Subjects graded ocular discomfort by using the Ora Calibra™ Ocular Discomfort Scale, 9 , 10 a 5-point scale (0–4) on which 0 is no discomfort and 4 is constant discomfort. Subjects also graded the severity of their dry eye symptoms by using the Ora Calibra™ Ocular Discomfort and 4-Symptom Questionnaire, 9 , 10 , 12 a 6-point scale (0–5) on which 0 is no pain and 5 is the worst and in which five ocular symptoms are individually graded: overall discomfort, burning, dryness, grittiness, and stinging.…”