Ocular Irritation test. EN 10993-23: 2021 - Biological evaluation of medical devices - Part 23: Tests for irritation. Annex D.2-Ocular Irritation test.

Test accredited by ENAC (Spanish National Accreditation Entity).

Test with the Certificate of Good Laboratory Practices (GLPs).

This test evaluates the potential of liquid, solids, sprays, aerosols medical devices and extracts of medical devices, to produce eye irritation.

To perform the eye irritation test according to ISO 10993-23 standard, healthy adult albino rabbits are used, to which the test product is administered in the conjunctival sac of one eye, and the negative control in the contralateral eye. A single animal is initially dosed and, if no irritation response is observed, at least two more animals are dosed. For test materials expected not to cause eye irritation, e.g, contact lens fluid, the standard allows all three rabbits to be dosed at the same time.

The eye irritation test is generally single dose, but if repeated exposure to the material is anticipated and the material has not shown a significant response in the acute test, a repeated exposure test can be performed, which should simulate the duration of use of the medical device in clinical situation.

For the single-dose test, the eyes of the animals are examined 1, 24, 48, and 72 hours after dosing, and a numerical grading of the ocular lesions observed at each time is assigned (reaction observed in the cornea, iris, and conjunctivae). The test can be extended to study the progression or reversibility of the lesions observed up to 21 days. For repeated exposure tests, the eyes of the animals should be evaluated immediately before and 1 hour after each dose. If after the last dose there is evidence of irritation, the test can be prolonged to assess the progression or reversibility of the lesions.

For acute exposure tests, the test material is considered irritating if a severe reaction in only one animal is observed and if a positive effect, at any of the observations, in the treated eye of more than one test animal is observed. If 3 animals are tested and a mild or moderate irritant effect is observed in only one of the treated eyes, additional animals should be tested. When more than 3 animals are treated in an acute exposure test and in repeated dose tests, the test material is considered an ocular irritant if more than half of the animals show a positive result at any stage of the observation in eyes treated with the test product.

Materials and end products that have demonstrated definite corrosion or severe irritation in a dermal study, shown to be a skin irritant, or are strongly acidic or alkaline (with pH 2 or less, or pH 11.5 or greater), should not be tested but should be labelled as a potential eye irritant.