Investigation in Corneal Sensation

Investigation in Variability and Repeatability of Corneal Sensation in a Normal Population

The aim is to find out more about how corneal sensory fibres react to different types of stimuli (liquid / tactile / nylon thread) and how this can be consciously perceived by the individual. Is it possible to generate a stimulus that delivers a repeatable and reliable response within a useful stimulus force range which allows an interpretation / evaluation of normal / expected activity of superficial nerve fibres in the cornea? The study group will be divided into two age groups, as sensitivity changes are thought to occur in dependence of age. In vivo confocal microscopy has shown that the density of corneal nerve fibres in the sub-basal nerve plexus decreases with age, which consequently would suggest that sensitivity should also decrease. A very interesting research question is to find out, if such sensitivity differences can be detected with the nature of the stimuli applied in this study.

Study Overview

• Status: Completed
• Conditions: Cornea; Sense Loss
• Intervention / Treatment: Device: Liquid Jet Esthesiometer Prototype; Device: Tactile Esthesiometer Prototype; Device: Cochet Bonnet esthesiometer

Detailed Description

The aim of this study is to gain more physiological knowledge about ocular surface sensation (corneal sensitivity), with application of three different concepts employing different types of stimuli for triggering a response from the pain sensitive nerve endings in the superficial cornea: 1) liquid jet (consisting of isotonic saline solution; prototype), 2) tactile stimulus (round plastic nozzle, prototype) 3) commercially available Cochet Bonnet esthesiometer (nylon thread). Measurements will be carried out on healthy eyes of subjects in two different age groups.

Current knowledge about human corneal sensitivity is limited, as applied methods for ocular surface sensation measurement are limited with regards to reproducibility / accuracy.

Corneal sensitivity represents a neurological response from the free nerve endings within the epithelium. They are sensitive to mechanical, electrical, chemical or thermal stimuli and hence have a protective function for the cornea. Corneal nerves play an important role in cell growth and proliferation of epithelial cells, wound healing and repair. In experimental studies, corneal denervation has been reported to result in epithelial changes: increased permeability, decreased proliferation, changed appearance and delayed wound healing. Therefore, intact corneal innervation is required to maintain the integrity of a normal corneal epithelium. Corneal sensory nerves are believed to play an important role in maintaining the resting tear flow, as their afferent impulses from the ocular surface lead to a reflex response, best described by the lacrimal functional unit: an integrated system comprising the ocular surface tissues (cornea, corneal limbus, conjunctiva, conjunctival blood vessels, and eyelids), the tear secreting components (main and accessory lacrimal glands, meibomian glands, conjunctival goblet, and epithelial cells), and the sensory and motor nerves that connect them.

Current knowledge about ocular surface sensitivity is insufficient, as currently available measurement possibilities lack repeatability and accuracy. Before a new instrument can be developed, more research is required, in order to find a suitable concept for precise sensitivity measurement. For this purpose, two new different concepts with different / new stimulus types will be applied repeatably on healthy eyes in this study. The aim is to find out more about how corneal sensory fibres react to different types of stimuli (liquid / tactile / nylon thread) and how this can be consciously perceived by the individual. Is it possible to generate a stimulus that delivers a repeatable and reliable response within a useful stimulus force range which allows an interpretation / evaluation of normal / expected activity of superficial nerve fibres in the cornea? The study group will be divided into two age groups, as sensitivity changes are thought to occur in dependence of age. In vivo confocal microscopy has shown that the density of corneal nerve fibres in the sub-basal nerve plexus decreases with age, which consequently would suggest that sensitivity should also decrease. A very interesting research question is to find out, if such sensitivity differences can be detected with the nature of the stimuli applied in this study.

• Study Type: Interventional
• Enrollment (Actual): 90
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Solothurn
    • Olten, Solothurn, Switzerland, 4600
      • Institute of Optometry, FHNW

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Group 'young age': 18 - 30 years of age; healthy eyes with Ocular Surface Disease Index Score </= 13
• Group 'advanced age': 50 - 70 years of age; healthy eyes with Ocular Surface Disease Index Score </= 13

Exclusion Criteria:

• Systemic disease that may affect ocular health, such as diabetes
• Injury and history of operations on the anterior segment of the eye
• regular application of systemic or ocular medication known to affect the tear film, specifically on the day of measurement
• rigid gas permeable contact lens wear
• soft contact lens wear less than 48 hours before study visit

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Group 'young age'; Group 'young age': 18 - 30 years of age; healthy eyes	Device: Liquid Jet Esthesiometer Prototype; Balanced salt solution with a pH value similar to the tear film uesd as a liquid jet stimulus for corneal sensation threshold measurement; Device: Tactile Esthesiometer Prototype; A round plastic nozzle (1.8mm diameter) used as a stimulus for corneal sensation threshold measurement; Device: Cochet Bonnet esthesiometer; A nylon thread (0.12mm diameter) used as a stimulus for corneal sensation threshold measurement
Other: Group 'advanced age'; Group 'advanced age': 50 - 70 years of age; healthy eyes	Device: Liquid Jet Esthesiometer Prototype; Balanced salt solution with a pH value similar to the tear film uesd as a liquid jet stimulus for corneal sensation threshold measurement; Device: Tactile Esthesiometer Prototype; A round plastic nozzle (1.8mm diameter) used as a stimulus for corneal sensation threshold measurement; Device: Cochet Bonnet esthesiometer; A nylon thread (0.12mm diameter) used as a stimulus for corneal sensation threshold measurement

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Repeatability of mechanical corneal sensation thresholds with the Cochet Bonnet esthesiometer	Evaluation of repeatability of mechanical corneal sensation thresholds for the measurement with the Cochet Bonnet instrument (in mN): the corneal sensation thresholds will be obtained with the double staircase method (with forced choice) and the stimulus represents a nylon thread, whereby its force is proportional to the length of the nylon thread applied to the corneal surface.	two weeks
Repeatability of mechanical corneal sensation thresholds with the liquid jet protoype esthesiometer	Evaluation of repeatability of mechanical corneal sensation thresholds for the measurement with the liquid jet esthesiometer prototype instrument (in mbar): the corneal sensation thresholds will be obtained with the double staircase method (with forced choice) and the stimulus represents a liquid jet (consisting of isotonic saline solution).	two weeks
Repeatability of mechanical corneal sensation thresholds with the tactile prototype esthesiometer	Evaluation of variability / repeatability of mechanical corneal sensation thresholds for the measurement with the tactile esthesiometer prototype instrument (in mN): the corneal sensation thresholds will be obtained with the double staircase method (with forced choice) and the stimulus represents a small, round plastic ball.	two weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation between corneal sensation thresholds with the Cochet Bonnet esthesiometer	Correlation between corneal sensitivity thresholds (in mN) obtained with the Cochet Bonnet esthesiometer	one day
Correlation between corneal sensation thresholds with the liquid jet prototype esthesiometer	Correlation between corneal sensitivity thresholds (in mbar) obtained with the liquid jet prototype esthesiometer	one day
Correlation between corneal sensation thresholds with the tactile prototype esthesiometer	Correlation between corneal sensitivity thresholds (in mN) obtained with the tactile prototype esthesiometer	one day
Correlation between corneal sensitivity thresholds, obtained with the Cochet Bonnet esthesiometer, and general pain perception	Correlation between corneal sensitivity thresholds obtained with the Cochet Bonnet esthesiometer and general pain perception, obtained with three different stimulus types, for each of the two different age groups recruited.	within two weeks
Correlation between corneal sensitivity thresholds, obtained with the liquid jet prototype esthesiometer, and general pain perception	Correlation between corneal sensitivity thresholds, obtained with the liquid jet prototype esthesiometer, and general pain perception	within two weeks
Correlation between corneal sensitivity thresholds, obtained with the tactile prototype esthesiometer, and general pain perception	Correlation between corneal sensitivity thresholds, obtained with the tactile prototype esthesiometer, and general pain perception	within two weeks
Comparison of corneal sensation thresholds, obtained with the Cochet Bonnet esthesiometer, between the two different age groups in the study population	Comparison of corneal sensation thresholds obtained with the Cochet Bonnet esthesiometer between the two different age groups in the study population	within two weeks
Comparison of corneal sensation thresholds, obtained with the liquid jet prototype esthesiometer, between the two different age groups in the study population	Comparison of corneal sensation thresholds, obtained with the liquid jet prototype esthesiometer, between the two different age groups in the study population	within two weeks
Comparison of corneal sensation thresholds, obtained with the tactile prototype esthesiometer, between the two different age groups in the study population	Comparison of corneal sensation thresholds, obtained with the tactile prototype esthesiometer, between the two different age groups in the study population	within two weeks

Collaborators and Investigators

• Sponsor: Daniela Nosch

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2019
• Primary Completion (Actual): November 30, 2019
• Study Completion (Actual): November 30, 2019

Study Registration Dates

• First Submitted: July 30, 2019
• First Submitted That Met QC Criteria: August 2, 2019
• First Posted (Actual): August 5, 2019

Study Record Updates

• Last Update Posted (Actual): December 6, 2019
• Last Update Submitted That Met QC Criteria: December 4, 2019
• Last Verified: December 1, 2019

More Information

Terms related to this study

• Keywords: corneal sensation; subbasal nerve plexus
• Other Study ID Numbers: 2019-01252

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Undecided

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No