Document Type

Presentation

Disciplines

Ophthalmology

Publication Details

British Contact Lens Association conference 2023.

https://www.bcla.org.uk/

Abstract

Aim: The aims of this research were; to establish a range of values for corneal sensitivity in normal subjects as measured using the Cochet-Bonnet aesthesiometer; to determine if the measurement of corneal sensitivity in one eye affected subsequent measurements in the fellow eye; and to determine if there is a difference in corneal sensitivity between fellow eyes.

Methods: Thirty four subjects aged between 18 and 30 who did not wear contact lenses had their central corneal sensitivity measured in both eyes. The average of three readings was taken as the measurement for each eye. In 15 subjects, measurement was taken from the right eye first and the left eye second and vice versa for the other 19 subjects. One researcher made all the first eye measurements and a second researcher made all the second eye measurements. Six subjects had the maximum measurable corneal sensitivity in both eyes so the data from these subjects was not included in analysis. The Cochet-Bonnet aesthesiometer used had a nylon filament diameter of 0.12mm. The sensitivity measurements were made in mm lengths of nylon filament and converted to pressure using the conversion chart supplied with the aesthesiometer.

Results: The range of sensitivity found for normal subjects was from 0.4g/mm2 to 0.8g/mm2. The average sensitivity was 0.51g/mm2. Median corneal sensitivities in first and second eyes measured were 0.39 g/mm2 and 0.51g/mm2; the distributions in the two groups did not differ significantly (Mann–Whitney U = 279.5, n1 = n2 = 28, P < 0.05 two-tailed). The range of differences found between fellow eyes was from 0 g/mm2 to 2.8 g/mm2.

Conclusion: Measurement of corneal sensitivity on one eye does not appear to affect the subsequent measurement on the fellow eye. The maximum corneal sensitivity measurement that can be made using this type of Cochet-Bonnet aesthesiometer is 0.4g/mm2. It is possible that the range of corneal sensitivity in normal subjects may in fact extend beyond this value. Using an undiseased eye as a control to check for decreases in corneal sensitivity in a fellow eye should be done with caution, bearing in mind that in this study inter-eye differences of 2.8 g/mm2 (corresponding to a filament length of 20mm) have been found in normal subjects.

DOI

https://doi.org/10.21427/ZT34-SZ38

Creative Commons License

Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.

Download
Contact the Author


Included in

Optometry Commons

Share

COinS