Registration Dossier

Administrative data

Endpoint:
eye irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16 February 2018 - 28 February 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)
Version / remarks:
09 October 2017
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Test animals / tissue source

Species:
other: bovine cornea
Strain:
other: not applicable
Details on test animals or tissues and environmental conditions:
Species: bovine cattle (Bos taurus).
Origin: bovine eyes were obtained from freshly slaughtered cattle at the abattoir EVA, Saint Pierre sur Dives, France.
Age: as French Authorities avoid the use of any organs from the head of bovines aged more than 12 months, bovine cattle were up to 12 months old (typically, 5 to 8 months old).
Reason for choice: bovine corneas are recommended by Regulatory Authorities for this type of study. They are adapted for the evaluation of potential ocular irritants since they are part of the target organ.
Transport from Supplier to Citoxlab France: the eyes were immerged in containers filled with cooled buffered Hanks medium and placed into a cooling-box with a sufficient amount of ice packs to ensure cooling until arrival at Citoxlab France. Containers with smooth internal surfaces were used for the transport to avoid damage to the corneas. Hank’s medium contained an antibiotic [Hank’s Balanced Salts Solution (HBSS) plus penicillin/streptomycin (100 units/100 µg/mL final)].

Preparation of the corneas
Upon arrival at Citoxlab France, the selection and preparation of corneas was performed as soon as possible. At each step of the preparation procedure, care was taken to avoid touching the corneas in order not to damage them.

Selection: a careful macroscopic examination was performed on all eyes to detect the presence of any defects (opacity, scratches, pigmentation, etc). Any eyes with defects were discarded. The examination was performed under a lamp, using HBSS in order to keep the eyes moistened and shiny. Particular attention was paid to the corneas and the eyes were swiveled in order to observe the fringe areas and any scratches directly under the light.
Preparation of the selected corneas: the tissues surrounding the eyeball were carefully pulled away and the cornea, surrounded by approximately 2 to 3 mm of sclera, was dissected out. The isolated corneas were stored in HBSS until all corneas had been prepared. The corneas were then used immediately


Test system

Vehicle:
unchanged (no vehicle)
Controls:
other: in vitro negative and positive controls
Amount / concentration applied:
TEST MATERIAL
- Amount applied: 750 µL per cornea
- Concentration: undiluted
Duration of treatment / exposure:
Exposure period of 10 minutes (± 30 seconds) at +32°C, followed by rinsing.
Observation period (in vivo):
Not applicable.
Duration of post- treatment incubation (in vitro):
2 hours (± 10 minutes) at +32°C.
Number of animals or in vitro replicates:
Triplicate corneas for each timepoint and tested substance (test item, negative control, positive control)
Details on study design:
ASSEMBLY OF THE CORNEAS AND THE HOLDERS
The corneas were mounted in the corneal holders with the endothelial side against the O-ring of the posterior chamber. Each cornea was identified with the corresponding holder number.

TREATMENT
The medium of the anterior chamber was removed and each item was applied onto the epithelium of the cornea, as specified in the § Test item, positive and negative controls application.

The treatment time of each series of three corneas was carefully measured with a chronometer, starting from the beginning of treatment of the first cornea of each series. Then each further operation (rinsing, measurement, etc.) was carried out in the same order for the three corneas of each series.

After application of the items, the holders were incubated vertically (cornea positioned horizontally with the treated side uppermost) in a water bath at +32°C (± 1°C), for the selected treatment time

REMOVAL OF TEST SUBSTANCE
The purpose of rinsing was to eliminate as much items as possible, while taking care not to damage the cornea. On completion of the treatment period, the test item was removed from the front opening of the anterior chamber (open-chamber method) and the epithelium was rinsed as follows:
- the anterior chamber was emptied using a metal gavage tube attached to a vacuum pump,
-- any residual amounts of the test item, adhering to the walls of the anterior chamber was first removed with a cotton bud and then using a pipette of heated cMEM (32°),
- the corneas were rinsed five times with pre-warmed cMEM containing phenol red (i.e. until the test item had been completely removed from the chamber or until the phenol red was not discoloured). Then, the corneas were finally rinsed with pre-warmed cMEM without phenol red.

POST INCUBATION
Following the 10-minute treatment and the rinsing step, the holders were incubated horizontally (corneas placed vertically) for 2 hours (± 10 minutes) in a water bath at +32°C (± 1°C). On completion of the 2-hour incubation period, the medium of both anterior and posterior chambers was renewed with pre-warmed cMEM (+32°C (± 1°C)), the second opacity measurement (OPT2) was then performed.

SCORING SYSTEM
- Opacity:
An opacitometer was used to measure light transmission (i.e. the level of opacity) through the center of each mounted cornea. A numerical opacity measurement (arbitrary unit) was displayed and recorded.

Just before the first opacity measurement (i.e. OPT0), the opacitometer was calibrated using specific calibrators. Values obtained for each calibrator were as follows:
- calibrator No. 1: set to 75,
- calibrator No. 2: from 145 to 155,
- calibrator No. 3: from 218 to 232.

Just before the second opacity measurement (i.e. OPT2), the opacitometer was calibrated using the calibrator No. 1 set to 75.
Just after each opacity measurement (OPT0 and OPT2), the calibration of the opacitometer was checked by using the calibrator No. 1. The obtained value was between 73 and 77 (see Table 2).
Corneal opacity was determined by reading each holder in the right hand chamber of the calibrated opacitometer, versus an empty holder (without cMEM, cornea and glasses), placed in the left hand chamber.
For opacity measurement, care was taken to make sure that no air bubbles were present within the holders containing corneas (by ensuring that each compartment was filled to overflowing with heated cMEM) and each holder was wiped dry.

- Permeability:
After the second opacity measurement, the medium of the anterior chamber was removed and the anterior chamber received 1 mL of a fluorescein solution.
As the test item was a non-surfactant liquid, the concentration of the fluorescein solution was 4 mg/mL.
Before use, the fluorescein solution was validated. For this purpose, the solution of fluorescein was diluted in cMEM in order to obtain a 5 µg/mL solution and the Optical Density at a wavelength of 490 nm (OD490 nm) of this dilution was measured. As the value obtained was between 0.850 and 0.940, the fluorescein solution was validated.
For each series of three corneas, a chronometer started from the fluorescein solution application time of the first cornea of the series. The holders were incubated vertically (cornea positioned horizontally with the fluorescein-treated side uppermost) in a water bath at +32°C (± 1°C) for 90 minutes (± 5 minutes).
At the end of incubation, the maximum volume of cMEM recoverable from the posterior chamber of each holder was transferred into an identified tube. The medium was homogenized prior to determination of OD490 nm, using single-use cuvettes (1 cm path length) and a spectrophotometer (cMEM used as the blank).

- Scoring:
In Vitro Irritancy Score (IVIS) = cOPT + (15 x cOD490 nm)

Results and discussion

In vitro

Results
Irritation parameter:
in vitro irritation score
Run / experiment:
mean
Value:
0
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of irritation
Remarks:
The test item was identified as not irritating
Other effects / acceptance of results:
MACROSCOPIC EXAMINATION:
Fluorescein fixation was observed on all corneas treated with the test item and one out of the three corneas treated with negative control (i.e. holder No. 56).
Opacity, fluorescein fixation and thickening of the corneas were observed on those treated with the positive control.

ACCEPTANCE OF RESULTS:
For the validation of an experiment, the following criteria had to be fulfilled:
- the mean In Vitro Irritancy Score (IVIS) of the positive control corneas should fall within two standard deviations of the historical mean,
- the mean opacity and mean OD490 nm of the negative control corneas should be less than the established upper limit of historical mean.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The test item was identified as not requiring classification for eye irritation or serious eye damage (UN GHS No Category).
Executive summary:

The objective of this study was to evaluate the potential irritant and corrosive properties of the test item to the eye. The Bovine Corneal Opacity and Permeability (BCOP) test method can identify chemicals inducing serious eye damage and chemicals not requiring classification for eye irritation or serious eye damage.

The design of this study was based on the OECD Guideline 437 and the study was performedin compliance with Citoxlab France standard operating procedures and with the OECD Principles of Good Laboratory Practice.

 

Method

Corneas obtained from freshly slaughtered calves were mounted in corneal holders. Both chambers of the corneal holder were filled with complemented MEM culture media (cMEM) and pre-incubated for 1 hour and 5 minutes (± 5 minutes) at +32°C.

A single experiment was performed using three corneas for each treated series (test item, positive control and negative control).

Before the treatment, a first opacity measurement was performed on each cornea using an opacitometer.

The test item was applied undiluted in a single experiment using a treatment time of 10 minutes and using the closed-chamber treatment method. Negative and positive controls were applied using the same treatment time and through the closed-chamber treatment method. At the completion of the treatment period, all items were removed from the front opening of the anterior chamber and the epithelia were rinsed.

The corneas were then incubated for 2 hours (± 10 minutes) at +32°C before a second opacity measurement was performed.

After the second opacity measurement, the medium of the anterior chamber was removed and filled with a fluorescein solution. The holders were then incubated vertically for 90 minutes (± 5 minutes) at +32°C.

At the end of the incubation period, the Optical Density of the solution from the posterior chamber of each holder was measured in order to determine the permeability of the cornea. Each cornea was then observed for opaque spots and other irregularities.

 

Results

Macroscopic examination

Fluorescein fixation was observed on all corneas treated with the test item.

In VitroIrritancy Score

All acceptance criteria were fulfilled. The study was therefore considered as valid.

The mean In Vitro Irritancy Score (IVIS) of the test item-treated corneas was: 0.

 

As the mean IVIS was < 3, the test item was considered as a test chemical not requiring classification for eye irritation or serious eye damage (UN GHS No Category).

 

Conclusion

the test item was identified as not requiring classification for eye irritation or serious eye damage (UN GHS No Category).