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Nosch DS, Käser E, Bracher T, Joos RE. Clinical application of the Swiss Liquid Jet Aesthesiometer for corneal sensitivity measurement. Clin Exp Optom 2024; 107:14-22. [PMID: 37019837 DOI: 10.1080/08164622.2023.2191782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 03/10/2023] [Indexed: 04/07/2023] Open
Abstract
CLINICAL RELEVANCE Corneal sensitivity represents an important indicator for corneal health, its innervation and hence also for ocular disease. It is therefore of great interest from a clinical and research perspective to quantify ocular surface sensation. BACKGROUND The aim of this prospective cross-sectional cohort study was to clinically test the within-day and day-to-day repeatability of the new Swiss Liquid Jet Aesthesiometer, employing small droplets of isotonic saline solution for repeatability, and correlate with the Cochet-Bonnet aesthesiometer in a cohort of participants of two different age groups, based on participant feedback (psychophysical method). METHODS Participants were recruited from two equally, large age groups: group A (18-30 years) and group B (50-70 years). The inclusion criteria were healthy eyes, Ocular Surface Disease Index (OSDI) ≤ 13, and no contact lens wear. Mechanical corneal sensitivity threshold measurements with means of liquid jet and Cochet-Bonnet methods were carried out twice during two visits (a total of four measurements), with a stimulus temperature equal to or slightly above the ocular surface temperature. RESULTS Ninety participants completed the study (n = 45 per age group, average age in group A: 24.2 ± 2.94 years, group B: 58.5 ± 5.71 years). The coefficient of repeatability for the liquid jet method was 2.56 dB within visits and 3.61 between visits. For the Cochet-Bonnet method, it was 2.27 dB within visits and 4.42 dB between visits (Bland Altman with bootstrap analysis). Moderate correlation was observed between the liquid jet and the Cochet-Bonnet method (r = 0.540, p < .001, robust linear regression). CONCLUSIONS Swiss liquid jet aesthesiometry offers a new examiner independent method for corneal sensitivity measurement with acceptable repeatability and moderate correlation with the Cochet-Bonnet aesthesiometer. It offers a large stimulus pressure range of 100-1500 mbar and a precision of 1 mbar. Stimulus intensity can be tuned more precisely and much smaller sensitivity fluctuations may be potentially detected.
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Affiliation(s)
- Daniela S Nosch
- Institute of Optometry, University of Applied Sciences and Arts Northwestern Switzerland (FHNW), Olten, Switzerland
| | | | - Tobias Bracher
- Institute of Optometry, University of Applied Sciences and Arts Northwestern Switzerland (FHNW), Olten, Switzerland
| | - Roland E Joos
- Institute of Optometry, University of Applied Sciences and Arts Northwestern Switzerland (FHNW), Olten, Switzerland
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Oganov A, Yazdanpanah G, Jabbehdari S, Belamkar A, Pflugfelder S. Dry eye disease and blinking behaviors: A narrative review of methodologies for measuring blink dynamics and inducing blink response. Ocul Surf 2023; 29:166-174. [PMID: 37257694 DOI: 10.1016/j.jtos.2023.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/28/2023] [Accepted: 05/28/2023] [Indexed: 06/02/2023]
Abstract
Dry eye disease (DED) is a leading cause of ophthalmology clinical encounters with prevalence ranging from 8.7% to 64% in various populations. Blinking is an endogenous process to refresh the tear film, clear debris and maintain quality vision. Altered blinking behavior is a common feature of DED and is implicated in the pathology of the disease. However, lack of a comprehensive review on the relationship between altered blinking behavior and DED is notable in the literature. Blinking behavior may be an effect of DED due to an unstable tear film sensitizing a motor response or be its cause due to destabilization of the tear film in conditions such as benign essential blepharospasm. In this comprehensive review, we summarize the current models and theories of tear film dynamics and blinking behavior to better understand their connection to DED and introduce contemporary technologies and measurement tools used in the evaluation and induction of blinking behavior. We also describe future directions of research to better understand the relationship between DED and blinking and explore therapies that address the abnormal blinking component of DED.
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Affiliation(s)
- Anthony Oganov
- Department of Ophthalmology, Renaissance School of Medicine, Stony Brook, NY, USA
| | - Ghasem Yazdanpanah
- Illinois Eye and Ear Infirmary, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Illinois, USA
| | - Sayena Jabbehdari
- Jones Eye Institute, University of Arkansas for Medical Sciences, Arkansas, USA
| | - Aditya Belamkar
- Indiana University School of Medicine, Indianapolis, IN, USA
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Liao X, Lai KKH, Aljufairi FMAA, Chen W, Hu Z, Wong HYM, Jia R, Wei Y, Tham CCY, Pang CP, Chong KKL. Ocular Surface Changes in Treatment-Naive Thyroid Eye Disease. J Clin Med 2023; 12:jcm12093066. [PMID: 37176507 PMCID: PMC10179143 DOI: 10.3390/jcm12093066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/03/2023] [Accepted: 04/20/2023] [Indexed: 05/15/2023] Open
Abstract
OBJECTIVE To investigate the association of meibomian gland dysfunction (MGD) and ocular surface exposure with tear film instability in untreated thyroid eye disease (TED) patients. METHODS A cross-sectional study of TED patients from September 2020 to September 2022 was conducted. Ocular surface parameters included ocular surface disease index (OSDI), tear meniscus height (TMH), non-invasive tear break-up time (NITBUT), partial blinking rate, lipid layer thickness (LLT), meibomian gland dropout (meiboscore), Schirmer's test, and corneal punctate epithelial erosions (PEE). Ocular surface exposure was assessed by the margin reflex distances of the upper and lower eyelid (MRD1 and MRD2), the amount of exophthalmos, lateral flare, and lagophthalmos. RESULTS In total, 152 eyes from 76 TED patients (64 females and 12 males, age 42.99 ± 12.28 years) and 93 eyes from 61 healthy controls (51 females and 10 males, age 43.52 ± 17.93 years) were examined. Compared with control eyes, TED eyes had higher OSDI, TMH, LLT, and PEE; shorter NITBUT; and worse meiboscore (all p < 0.05). They also had larger amounts of exophthalmos, longer MRD1, more lateral flare, and lagophthalmos. Multivariate analysis identified an association of the tear film instability with lagophthalmos (β = -1.13, 95%CI: -2.08, -0.18) and severe MGD in the lower eyelid (β = -5.01, 95%CI = -7.59, -2.43). CONCLUSIONS Dry eye in TED is mainly manifested as evaporative dry eye disease. Severe lower eyelid MGD and worse lagophthalmos were significantly associated with tear film instability in treatment-naive TED patients.
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Affiliation(s)
- Xulin Liao
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Kenneth Ka Hei Lai
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
- Department of Ophthalmology, Tung Wah Eastern Hospital, Hong Kong SAR, China
| | - Fatema Mohamed Ali Abdulla Aljufairi
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
- Department of Ophthalmology, Salmaniya Medical Complex, Government Hospitals, Manama 435, Bahrain
| | - Wanxue Chen
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Zhichao Hu
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Hanson Yiu Man Wong
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ruofan Jia
- Department of Statistics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Yingying Wei
- Department of Statistics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Clement Chee Yung Tham
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Chi Pui Pang
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Kelvin Kam Lung Chong
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
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Fang W, Lin ZX, Yang HQ, Zhao L, Liu DC, Pan ZQ. Changes in corneal nerve morphology and function in patients with dry eyes having type 2 diabetes. World J Clin Cases 2022; 10:3014-3026. [PMID: 35647133 PMCID: PMC9082719 DOI: 10.12998/wjcc.v10.i10.3014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 12/24/2021] [Accepted: 03/15/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Dry eye syndrome (DES) is a common disease with various clinical manifestations. DES had a significant association with diabetes. Blink reflex (BR) is also known as trigeminal nerve facial reflex. The stimulation of corneal nerves is one of the origins of BR stimulation. The parasympathetic fibers sent out through the facial nerve are the outlet of tear reflexes. BR can be used to assess the function of the corneal nerve closed-loop; however, whether the BR changes in these patients is unclear. AIM To understand the morphology and function of the corneal nerve in patients with dry eyes having diabetes or not. METHODS This study enrolled 131 patients who visited the inpatient and outpatient services of ophthalmology and endocrinology departments between January 2019 to August 2020 with subjective symptoms of dry eyes and non-dry eye reasons, as well as volunteers such as colleagues. The patients were divided into four groups: DEwDM, with dry eyes having type 2 diabetes mellitus (T2DM); DMnDE, with T2DM not having dry eyes; DEnDM, with dry eyes not having diabetes; and nDMnDE, with neither dry eyes nor diabetes. The tear film break-up time, Schirmer I test, in vivo confocal microscopy, and BR were performed. RESULTS The DEwDM, DMnDE, DEnDM, and nDMnDE groups included 56, 22, 33, and 20 patients, respectively. Sex and age were not statistically different among the four groups. The nerve fiber length (NFL) of patients in the DEwDM, DEnDM, and DMnDE groups reduced (P < 0.001, P = 0.014, and P = 0.001, respectively). No significant difference in corneal nerve fiber density (NFD) (P = 0.083) and corneal nerve branch density (NBD) (P = 0.195) was found among the four groups. The R1 Latency of blink reflexes increased only in the DEwDM group (P = 0.008, P = 0.001, P < 0.001, compared with the DMnDE, DEnDM, and nDMnDE groups, respectively). The NBD and R1 Latency were different between DEwDM and DEnDM groups in patients with moderate and severe dry eyes. CONCLUSION The corneal nerve morphology changed in patients with dry eyes or diabetes, or with both, while the function of corneal nerve closed-loop reduced only in those with dry eyes and diabetes.
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Affiliation(s)
- Wei Fang
- Department of Ophthalmology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
- Department of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100005, Beijing, China
| | - Zhong-Xi Lin
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - Hui-Qing Yang
- Department of Ophthalmology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - Lei Zhao
- Department of Endocrinology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - Da-Chuan Liu
- Department of Ophthalmology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - Zhi-Qiang Pan
- Department of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100005, Beijing, China
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Situ P, Simpson TL, Begley CG, Keir N. Role of diurnal variation of corneal sensory processing in contact lens discomfort. Ocul Surf 2020; 18:770-776. [PMID: 32828970 DOI: 10.1016/j.jtos.2020.08.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 08/06/2020] [Accepted: 08/14/2020] [Indexed: 02/07/2023]
Abstract
PURPOSE To examine the diurnal variation of corneal threshold and suprathreshold sensory processing, symptoms, and tear secretion in symptomatic and asymptomatic contact lens (CL) wearers and controls. METHODS 26 symptomatic and 25 asymptomatic CL wearers and 15 asymptomatic non-CL wearing controls participated. Cooling thresholds, symptoms and tear meniscus height (TMH) were measured on each of 3 measurement days (random order) on the following schedules; Day-1 within 1 h of awakening (Baseline) and 3, 6 and 9 h later, Day-2 baseline and 9 h later (CLs worn in CL group) and Day-3 baseline and 9 h later. Magnitudes estimates for threshold-scaled suprathreshold stimuli were also estimated on Day-3. Data were analyzed using mixed models and repeated measures ANOVA. RESULTS Cooling thresholds for the symptomatic group were lower and decreased over Day-1 (p < 0.008) and after 8 h of CL wear on Day-2 (p < 0.001) and were paralleled by increased symptoms (all p < 0.001), whereas minimal variations were found in the asymptomatic and control groups. Magnitude estimates for suprathreshold stimuli were higher (p ≤ 0.002) in the symptomatic group but did not differ significantly over the day. TMH varied little over time and was lower in the symptomatic group, but the difference was not statistically significant. CONCLUSION Corneal sensitivity and symptoms, but not TMH, increased diurnally irrespective of CL wear in symptomatic CL wearers. These results reveal the essential role of neurosensory abnormalities in CL discomfort and suggest involvement of a central mechanism in the diurnally increased symptoms of these patients.
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Affiliation(s)
- Ping Situ
- School of Optometry, Indiana University, Bloomington, IN, USA.
| | - Trefford L Simpson
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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Sanchis-Jurado V, Talens-Estarelles C, Esteve-Taboada JJ, Pons ÁM, García-Lázaro S. Non-invasive high-speed blinking kinematics characterization. Graefes Arch Clin Exp Ophthalmol 2020; 258:2701-2714. [PMID: 32524240 DOI: 10.1007/s00417-020-04782-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 05/25/2020] [Accepted: 06/01/2020] [Indexed: 11/30/2022] Open
Abstract
PURPOSE The objective of this study was to analyze the differences in blinking kinematics of spontaneous and voluntary blinks using for the first time a self-developed, non-invasive, and image processing-based method. METHODS The blinks of 30 subjects were recorded for 1 min with the support of an eye-tracking device based on a high-speed infrared video camera, working at 250 frames per second, under two different experimental conditions. For the first condition, subjects were ordered to look in the straightforward position at a fixation target placed 1 m in front of them, with no further instructions. For the second, subjects were additionally asked to blink only following a sound signal every 6 s. RESULTS Mean complete blinks increased by a factor of 1.7 from the spontaneous to the voluntary condition while mean incomplete blinks reduced significantly by a factor of 0.4. In both conditions, closing mean and peak velocities were always significantly greater and durations significantly lower than opening ones. When comparing the values for each condition, velocities and amplitudes for the voluntary condition were always greater than the corresponding values for spontaneous. CONCLUSION Voluntary blinks revealed significant kinematic differences compared to spontaneous, thus supporting a different supranuclear pathway organization. This study presents a new method, based on image analysis, for the non-invasive kinematic characterization of blinking.
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Affiliation(s)
- V Sanchis-Jurado
- Department of Optics & Optometry & Vision Sciences, University of Valencia, Dr. Moliner, 50 46100, Burjassot, Valencia, Spain
| | - Cristian Talens-Estarelles
- Department of Optics & Optometry & Vision Sciences, University of Valencia, Dr. Moliner, 50 46100, Burjassot, Valencia, Spain.
| | - J J Esteve-Taboada
- Department of Optics & Optometry & Vision Sciences, University of Valencia, Dr. Moliner, 50 46100, Burjassot, Valencia, Spain
| | - Á M Pons
- Department of Optics & Optometry & Vision Sciences, University of Valencia, Dr. Moliner, 50 46100, Burjassot, Valencia, Spain
| | - S García-Lázaro
- Department of Optics & Optometry & Vision Sciences, University of Valencia, Dr. Moliner, 50 46100, Burjassot, Valencia, Spain
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Yorzinski JL. Blinking behavior in great‐tailed grackles (
Quiscalus mexicanus
) increases during simulated rainfall. Ethology 2020. [DOI: 10.1111/eth.13003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Jessica L. Yorzinski
- Department of Ecology and Conservation Biology Texas A&M University College Station TX USA
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8
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McMonnies CW. The clinical and experimental significance of blinking behavior. JOURNAL OF OPTOMETRY 2020; 13:74-80. [PMID: 31992536 PMCID: PMC7182785 DOI: 10.1016/j.optom.2019.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/17/2019] [Accepted: 09/22/2019] [Indexed: 05/23/2023]
Abstract
Evaluations of tear functions frequently involve some form of voluntary control over blink behaviour. To the degree that voluntary control of blinking risks departure from normal-range spontaneous blinking, the tear function findings from such studies may be confounded. Even subject awareness that blinking is being assessed may influence findings if such awareness results in any degree of voluntary control. Ideally, the influence on blink rate and tear functions induced by therapeutic or experimental interventions could be measured against a normal-range baseline spontaneous blink rate in order that any differences found could be validly attributed to those interventions. Sometimes pre-intervention 'rest-related' baseline blink rates have been incorrectly described as 'basal' blink rates without specification of pre-intervention conditions of 'rest' or consideration of any contributions from voluntary control. Also, studies which use only blink rates to measure blink efficiency ignore the critically important contribution of incomplete blinking to blink inefficiency. This review finds that the assessment of normal-range spontaneous blink rates depends on measurement conditions which have frequently been ignored previously. For example, normal-range spontaneous blink rates appear more likely to occur with fixation targets which have a disengaged affect and an associated neutral influence on and from dopamine activity. Ideally, fixation targets should also involve minimal cognitive loading and vision demands. In addition, normal-range (symptom free) spontaneous blink rates are more likely to be assessed in a comfortable ambient environment without subject awareness that blink behaviour is being assessed and when voluntary blinking is not involved.
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Affiliation(s)
- Charles W McMonnies
- School of Optometry and Vision Science, University of New South Wales, Kensington 2052, Australia.
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Topical Review: Effects of Contact Lens Wear on Corneal, Conjunctival, and Lid Margin Sensitivity. Optom Vis Sci 2019; 96:790-801. [DOI: 10.1097/opx.0000000000001429] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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10
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Yorzinski JL, Argubright S. Wind Increases Blinking Behavior in Great-Tailed Grackles (Quiscalus mexicanus). Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00330] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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Situ P, Begley CG, Simpson TL. Effects of Tear Film Instability on Sensory Responses to Corneal Cold, Mechanical, and Chemical Stimuli. Invest Ophthalmol Vis Sci 2019; 60:2935-2941. [PMID: 31284310 PMCID: PMC6615367 DOI: 10.1167/iovs.19-27298] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Purpose To investigate the effects of tear film instability (TFI) induced by sustained tear exposure (STARE) on sensory responses to corneal cold, mechanical, and chemical stimuli. Methods Fifteen normal subjects were enrolled. TFI was induced during 10 repeated trials of STARE. Pneumatic cold, mechanical, and chemical stimuli were delivered using a computer-controlled Belmonte esthesiometer on three separate visits. The magnitude of the sensory responses to threshold and suprathreshold (1.25 and 1.50 times threshold levels) stimuli were assessed for intensity, coolness or warmness, irritation and pain, using a 0 (none) to 100 (very strong) scale, before and after STARE trials. Symptoms of ocular discomfort were evaluated using the Current Symptom Questionnaire (CSQ). Repeated measures ANOVA was used for data analysis. Results Following STARE trials, the intensity and coolness ratings to cooling stimuli decreased (P = 0.043 and 0.044 for intensity and coolness, respectively), while rated irritation to mechanical stimuli was increased (P = 0.024). The CSQ scores also increased regardless of visits (all P < 0.001). Intensity ratings, coolness to room temperature stimuli and irritation to mechanical and chemical stimuli increased for all suprathreshold stimuli with increasing stimulus levels (P ≤ 0.005). Conclusions Repeated TFI induced by STARE affects neurosensory function of the ocular surface. The decrease in reports of cooling and increase in irritation after repeated TFI suggest a complex interaction of neural mechanisms (particularly nonnociceptive cold and nociceptive mechanical) giving rise to ocular surface sensation in humans.
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Affiliation(s)
- Ping Situ
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Carolyn G Begley
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Trefford L Simpson
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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Guillon M, Shah S. Rationale for 24-hour management of dry eye disease: A review. Cont Lens Anterior Eye 2019; 42:147-154. [DOI: 10.1016/j.clae.2018.11.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 11/05/2018] [Accepted: 11/08/2018] [Indexed: 12/30/2022]
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Rodriguez JD, Lane KJ, Ousler GW, Angjeli E, Smith LM, Abelson MB. Blink: Characteristics, Controls, and Relation to Dry Eyes. Curr Eye Res 2017; 43:52-66. [PMID: 29043838 DOI: 10.1080/02713683.2017.1381270] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Blink is a complex phenomenon that is profoundly affected by diverse endogenous and exogenous stimuli. It has been studied in the context of cognition, emotional, and psychological states, as an indicator of fatigue and sleepiness, particularly in the automobile and transportation industry, in visual tasking, and finally, as it relates to tear film stability and ocular surface health. The fact that it is highly variable and has input from so many sources makes it very difficult to study. In the present review, the behavior of blink in many of these systems is discussed, ultimately returning in each instance to a discussion of how these factors affect blink in the context of dry eyes. Blink is important to ocular surface health and to an individual's optimal functioning and quality of life. Disturbances in blink, as cause or effect, result in a breakdown of tear film stability, optical clarity, and visual function.
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Affiliation(s)
| | | | | | | | | | - Mark B Abelson
- a Ora, Inc , Andover , MA , USA.,b Department of Ophthalmology , Harvard Medical School , Boston , MA , USA
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King-Smith PE, Begley CG, Braun RJ. Mechanisms, imaging and structure of tear film breakup. Ocul Surf 2017; 16:4-30. [PMID: 28935579 DOI: 10.1016/j.jtos.2017.09.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 08/10/2017] [Accepted: 09/15/2017] [Indexed: 12/14/2022]
Abstract
Tear film breakup (BU) is an important aspect of dry eye disease, as a cause of ocular aberrations, irritation and ocular surface inflammation and disorder. Additionally, measurement of breakup time (BUT) is a common clinical test for dry eye. The current definition of BUT is subjective; here, a more objective concept of "touchdown" - the moment when the lipid layer touches down on the corneal surface - is proposed as an aid to understanding processes in early and late stages of BU development. Models of BU have generally been based on the assumption that a single mechanism is involved. In this review, it is emphasized that BU does not have a single explanation but it is the end result of multiple processes. A three-way classification of BU is proposed - "immediate," "lid-associated," and "evaporative." Five different types of imaging systems are described, which have been used to help elucidate the processes involved in BU and BUT; a new method, "high resolution chromaticity images," is presented. Three directions of tear flow - evaporation, osmotic flow out of the ocular surface, and "tangential flow" along the ocular surface - determine tear film thinning between blinks, leading to BU. Ten factors involved in BU and BUT, both before and after touchdown, are discussed. Future directions of research on BU are proposed.
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Abstract
Pain associated with mechanical, chemical, and thermal heat stimulation of the ocular surface is mediated by trigeminal ganglion neurons, while cold thermoreceptors detect wetness and reflexly maintain basal tear production and blinking rate. These neurons project into two regions of the trigeminal brain stem nuclear complex: ViVc, activated by changes in the moisture of the ocular surface and VcC1, mediating sensory-discriminative aspects of ocular pain and reflex blinking. ViVc ocular neurons project to brain regions that control lacrimation and spontaneous blinking and to the sensory thalamus. Secretion of the main lacrimal gland is regulated dominantly by autonomic parasympathetic nerves, reflexly activated by eye surface sensory nerves. These also evoke goblet cell secretion through unidentified efferent fibers. Neural pathways involved in the regulation of meibomian gland secretion or mucin release have not been identified. In dry eye disease, reduced tear secretion leads to inflammation and peripheral nerve damage. Inflammation causes sensitization of polymodal and mechano-nociceptor nerve endings and an abnormal increase in cold thermoreceptor activity, altogether evoking dryness sensations and pain. Long-term inflammation and nerve injury alter gene expression of ion channels and receptors at terminals and cell bodies of trigeminal ganglion and brainstem neurons, changing their excitability, connectivity and impulse firing. Perpetuation of molecular, structural and functional disturbances in ocular sensory pathways ultimately leads to dysestesias and neuropathic pain referred to the eye surface. Pain can be assessed with a variety of questionaires while the status of corneal nerves is evaluated with esthesiometry and with in vivo confocal microscopy.
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Rahman M, Shiozaki K, Okamoto K, Thompson R, Bereiter DA. Trigeminal brainstem modulation of persistent orbicularis oculi muscle activity in a rat model of dry eye. Neuroscience 2017; 349:208-219. [PMID: 28288901 PMCID: PMC5408357 DOI: 10.1016/j.neuroscience.2017.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 02/23/2017] [Accepted: 03/02/2017] [Indexed: 01/16/2023]
Abstract
Altered corneal reflex activity is a common feature of dry eye disease (DE). Trigeminal sensory nerves supply the ocular surface and terminate at the trigeminal interpolaris/caudalis (ViVc) transition and spinomedullary (VcC1) regions. Although both regions contribute to corneal reflexes, their role under dry eye conditions is not well defined. This study assessed the influence of local inhibitory and excitatory amino acid neurotransmission at the ViVc transition and VcC1 regions on hypertonic saline (HS) evoked orbicularis oculi muscle activity (OOemg) in urethane-anesthetized male rats after exorbital gland removal (DE). HS increased the magnitude of long-duration OOemg activity (OOemgL, >200ms) in DE compared to sham rats, while short-duration OOemg activity (OOemgS, <200ms) was similar for both groups. Inhibition of the ViVc transition by muscimol, a GABAA receptor agonist, greatly reduced HS-evoked OOemgL activity in DE rats, whereas injections at the VcC1 region had only minor effects in both groups. Blockade of GABAA receptors by bicuculline methiodide at the ViVc transition or VcC1 region increased HS-evoked OOemgL activity in DE rats. Blockade of N-methyl-D-aspartate (NMDA) receptors at either region reduced HS-evoked OOemgL activity in DE and sham rats. GABAαβ3 receptor density was reduced at the ViVc transition, while NMDA receptor density was increased at both regions in DE rats. Loss of GABAergic inhibition at the ViVc transition coupled with enhanced NMDA excitatory amino acid neurotransmission at the ViVc transition and the VcC1 region likely contribute to altered corneal reflexes under dry eye conditions.
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Affiliation(s)
- Mostafeezur Rahman
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware St. SE, Minneapolis, MN 55455, USA.
| | - Kazunari Shiozaki
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware St. SE, Minneapolis, MN 55455, USA
| | - Keiichiro Okamoto
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware St. SE, Minneapolis, MN 55455, USA
| | - Randall Thompson
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware St. SE, Minneapolis, MN 55455, USA
| | - David A Bereiter
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware St. SE, Minneapolis, MN 55455, USA
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Abstract
PURPOSE To assess diurnal changes in the signs and symptoms of dry eyes and their relationship to diurnal interblink interval (IBI) in normal subjects and in subjects with dry eye. METHODS Blink data were collected from 9:00 AM to 8:00 PM during 2 days of normal activity using an electrocardiogram monitoring device. All subjects recorded ocular discomfort (0-5 scale) and primary activity hourly each day in a diary. Inferior and central fluorescein staining was graded by slit lamp (0-4) at the start and end of each day. Blink activity was detected using an algorithm based on recognition of the waveform corresponding to the kinematic properties of the blink signal. RESULTS Normal subjects (N = 12) reported negligible symptoms, and results did not show a diurnal change in group hourly IBI. Mean daily IBI for the group with dry eye (N = 15) (4.63 ± 1.63 s) was shorter than that for the normal group (5.28 ± 1.48 s) (P = 0.0483). Correlation of diurnal symptoms and mean hourly IBI was relatively weak (r = -0.248). A repeated-measures model found IBI to be significantly associated with the time of day (P = 0.0028). Inferior corneal staining showed a small but significant diurnal increase for both normal group and group with dry eyes. CONCLUSIONS Diurnal blink tracking reveals significant trending with symptoms. Diurnal change in IBI may be an appropriate surrogate for symptoms in the study of dry eye.
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18
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19
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Wu Z, Begley CG, Port N, Bradley A, Braun R, King-Smith E. The Effects of Increasing Ocular Surface Stimulation on Blinking and Tear Secretion. Invest Ophthalmol Vis Sci 2015; 56:4211-20. [PMID: 26132780 PMCID: PMC4495814 DOI: 10.1167/iovs.14-16313] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/20/2015] [Indexed: 12/18/2022] Open
Abstract
PURPOSE To investigate the effect of varying levels of ocular surface stimulation on the timing and amplitude of the blink and tear secretion. METHODS Following instillation of fluorescein dye, increasing levels of air flow were directed toward the central corneas of 10 healthy subjects. Interblink interval (IBI), tear meniscus height (TMH), and fluorescence intensity were measured simultaneously. Because blinking can obscure changes in TMH, we developed novel measures of tear secretion by calculating tear meniscus fluorescein concentration (TMFC) from intensity using a mathematical model. The change of TMH and TMFC over trials and the slope of the TMFC within each IBI (IBI-TTR) were further calculated. RESULTS The mean IBI was decreased by 8.08 ± 8.54 seconds from baseline to maximum air stimulation. The TMH increase was highly variable (0.41 ± 0.39 mm) among subjects, compared to the fluorescence tear turnover metrics: decrease in TMFC of 2.84 ± 0.98 natural logarithm or ln(%) and IBI-TTR of 0.065 ± 0.032 ln(%)/sec. Ocular surface stimulation was highly correlated with the TMFC and IBI-TTR, but less so with TMH (Pearson's r = 0.71, 0.69, and 0.40, P < 0.01, respectively). Blinking and tearing were significantly correlated with each other (Pearson's r = 0.56, P < 0.01), but tearing lagged behind by an average of 6.54 ± 4.07 seconds. CONCLUSIONS Blinking and tearing share a common origin with sensory stimulation at the ocular surface. Both showed a dose-response increase with surface stimulation and were correlated with each other. These methods can potentially be used to understand alterations in ocular surface sensory function and associated protective responses in dry eye and other disorders of the ocular surface.
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Affiliation(s)
- Ziwei Wu
- School of Optometry Indiana University, Bloomington, Indiana, United States
| | - Carolyn G. Begley
- School of Optometry Indiana University, Bloomington, Indiana, United States
| | - Nicholas Port
- School of Optometry Indiana University, Bloomington, Indiana, United States
| | - Arthur Bradley
- School of Optometry Indiana University, Bloomington, Indiana, United States
| | - Richard Braun
- Department of Mathematical Sciences, University of Delaware, Newark, Delaware, United States
| | - Ewen King-Smith
- College of Optometry, The Ohio State University, Columbus, Ohio, United States
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Gisler C, Ridi A, Hennebert J, Weinreb RN, Mansouri K. Automated Detection and Quantification of Circadian Eye Blinks Using a Contact Lens Sensor. Transl Vis Sci Technol 2015; 4:4. [PMID: 25635236 PMCID: PMC4306263 DOI: 10.1167/tvst.4.1.4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 11/28/2014] [Indexed: 12/16/2022] Open
Abstract
PURPOSE To detect and quantify eye blinks during 24-hour intraocular pressure (IOP) monitoring with a contact lens sensor (CLS). METHODS A total of 249 recordings of 24-hour IOP patterns from 202 participants using a CLS were included. Software was developed to automatically detect eye blinks, and wake and sleep periods. The blink detection method was based on detection of CLS signal peaks greater than a threshold proportional to the signal amplitude. Three methods for automated detection of the sleep and wake periods were evaluated. These relied on blink detection and subsequent comparison of the local signal amplitude with a threshold proportional to the mean signal amplitude. These methods were compared to manual sleep/wake verification. In a pilot, simultaneous video recording of 10 subjects was performed to compare the software to observer-measured blink rates. RESULTS Mean (SD) age of participants was 57.4 ± 16.5 years (males, 49.5%). There was excellent agreement between software-detected number of blinks and visually measured blinks for both observers (intraclass correlation coefficient [ICC], 0.97 for observer 1; ICC, 0.98 for observer 2). The CLS measured a mean blink frequency of 29.8 ± 15.4 blinks/min, a blink duration of 0.26 ± 0.21 seconds and an interblink interval of 1.91 ± 2.03 seconds. The best method for identifying sleep periods had an accuracy of 95.2 ± 0.5%. CONCLUSIONS Automated analysis of CLS 24-hour IOP recordings can accurately quantify eye blinks, and identify sleep and wake periods. TRANSLATIONAL RELEVANCE This study sheds new light on the potential importance of eye blinks in glaucoma and may contribute to improved understanding of circadian IOP characteristics.
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Affiliation(s)
- Christophe Gisler
- ICT Institute, University of Applied Sciences Western Switzerland, Fribourg, Switzerland
| | - Antonio Ridi
- ICT Institute, University of Applied Sciences Western Switzerland, Fribourg, Switzerland
| | - Jean Hennebert
- ICT Institute, University of Applied Sciences Western Switzerland, Fribourg, Switzerland
| | - Robert N. Weinreb
- Hamilton Glaucoma Center, Department of Ophthalmology, University of California, San Diego, USA
| | - Kaweh Mansouri
- Glaucoma sector, Department of Ophthalmology, Geneva University Hospitals, Geneva, Switzerland
- Department of Ophthalmology, University of Colorado School of Medicine, Denver, USA
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Rahman M, Okamoto K, Thompson R, Bereiter DA. Trigeminal pathways for hypertonic saline- and light-evoked corneal reflexes. Neuroscience 2014; 277:716-23. [PMID: 25086311 DOI: 10.1016/j.neuroscience.2014.07.052] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 07/03/2014] [Accepted: 07/04/2014] [Indexed: 11/18/2022]
Abstract
Cornea-evoked eyeblinks maintain tear film integrity on the ocular surface in response to dryness and protect the eye from real or potential damage. Eyelid movement following electrical stimulation has been well studied in humans and animals; however, the central neural pathways that mediate protective eyeblinks following natural nociceptive signals are less certain. The aim of this study was to assess the role of the trigeminal subnucleus interpolaris/caudalis (Vi/Vc) transition and subnucleus caudalis/upper cervical cord (Vc/C1) junction regions on orbicularis oculi electromyographic (OOemg) activity evoked by ocular surface application of hypertonic saline or exposure to bright light in urethane anesthetized male rats. The Vi/Vc and Vc/C1 regions are the main sites of termination for trigeminal afferent nerves that supply the ocular surface, while hypertonic saline (saline=0.15-5M) and bright light (light=5k-20klux) selectively activate ocular surface and intraocular trigeminal nerves, respectively, and excite second-order neurons at the Vi/Vc and Vc/C1 regions. Integrated OOemg activity, ipsilateral to the applied stimulus, increased with greater stimulus intensities for both modalities. Lidocaine applied to the ocular surface inhibited OOemg responses to hypertonic saline, but did not alter the response to light. Lidocaine injected into the trigeminal ganglion blocked completely the OOemg responses to hypertonic saline and light indicating a trigeminal afferent origin. Synaptic blockade by cobalt chloride of the Vi/Vc or Vc/C1 region greatly reduced OOemg responses to hypertonic saline and bright light. These data indicate that OOemg activity evoked by natural stimuli known to cause irritation or discomfort in humans depends on a relay in both the Vi/Vc transition and Vc/C1 junction regions.
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Affiliation(s)
- M Rahman
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware Street SE, Minneapolis, MN 55455, USA.
| | - K Okamoto
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware Street SE, Minneapolis, MN 55455, USA
| | - R Thompson
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware Street SE, Minneapolis, MN 55455, USA
| | - D A Bereiter
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Moos Tower 18-186, 515 Delaware Street SE, Minneapolis, MN 55455, USA
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