Investigation of the sensitivity of the cornea
Last reviewed: 23.04.2024
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The cornea is a highly sensitive shell of the eyeball. With various pathological conditions of the eye, its sensitivity can be significantly reduced or completely disappear, so its definition can be a very informative indicator in establishing the diagnosis.
Research is carried out in various ways. Some methods allow you to obtain indicative data, while others - more accurate. For an approximate determination of the level of tactile sensitivity of the cornea, a moistened cotton wick is used, which is touched to the cornea first in the central part, and then at four points on the periphery with the patient's eyes wide open. The lack of reaction to the touch of the wick indicates gross abnormalities of sensitivity. More subtle studies of the sensitivity of the cornea are carried out with the help of special graded hairs (Frey-Samoilov method), algesimeters and keratoesthesiometers.
In our country for a long period of time, a hair method was used to determine the tactile sensitivity of the cornea. It consists in successive contact of 13 points of the cornea with three (with a force of 0.3, 1 and 10 g per 1 mm 3 ) or four (add a hair with a force of 3 g per 1 mm 3 ) hairs. Normally, a hair whose pressure is 0.3 g / mm 3 is felt at 7-8 points, 1 g / mm 3 at 11-12 points, and a hair that exerts pressure 10 g / mm 3 causes not only tactile, but also painful sensations. This method is simple and accessible, but not without drawbacks: standardization and sterilization of hairs is impossible, as well as determination of the threshold perception value. Algezimeters created by BL Radzikhovskii and A. N. Dobromyslov are devoid of most of these shortcomings, but they also can not determine the threshold sensitivity of the cornea, and the position of the patient lying down is not always convenient for research.
In the technical respect, the most advanced at the present time are optical-electronic esthesiometers.
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