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Eye irritation

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eye irritation: in vitro / ex vivo
Bovine Corneal Opacity and Permeability (BCOP) test
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From August 09, 2013 to August 09, 2013
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
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)
GLP compliance:
yes (incl. certificate)

Test material

Test material form:

Test animals / tissue source

Details on test animals or tissues and environmental conditions:
Bovine eyes from young adult cattle were obtained from the slaughterhouse, where the eyes were excised by a slaughterhouse employee as soon as possible after slaughter.

Test system

unchanged (no vehicle)
yes, concurrent positive control
yes, concurrent negative control
Amount / concentration applied:
20% w/v in 0.9% w/v sodium chloride
Duration of treatment / exposure:
240 minutes
Duration of post- treatment incubation (in vitro):
2 h (followed by opacity measurement and the permeability of the corneas was determined after a 90 minutes incubation period with sodium fluorescein)
Number of animals or in vitro replicates:
Details on study design:
The Bovine Corneal Opacity and Permeability (BCOP) test is an organic model that provides short-term maintenance of normal physiological and biological function of the bovine cornea in an isolated system. In this test method, damage by the test substance is assessed by quantitative measurements of changes in corneal opacity and permeability with an opacitymeter and an ultraviolet/visible spectrophotometer, respectively.

1. Preparation of corneas
The isolated corneas were stored in a petri dish with cMEM containing 1% (v/v) L-glutamine and 1% (v/v) Foetal Bovine Serum. The isolated corneas were mounted in a corneal holder (one cornea per holder) of BASF with the endothelial side against the O-ring of the posterior half of the holder. The anterior half of the holder was positioned on top of the cornea and tightened with screws. The compartments of the corneal holder were filled with cMEM of 32 +/- 1°C. The corneas were incubated for the minimum of 1 hour at 32 +/- 1°C.

2. Opacity reading
After the incubation period, the medium was removed from both compartments and replaced with fresh cMEM. Opacity determinations were performed on each of the corneas using an opacitometer. The opacity of each cornea was read against a cMEM filled chamber, and the initial opacity reading thus determined was recorded.

3. Treatment of corneas and opacity measurements
The medium from the anterior compartment was removed and 750 µl of the negative control and 20% (w/v) imidazole solution (positive control) were introduced onto the epithelium of the cornea. The test substance was weighed in a bottle and applied directly on the corneas in such a way that the cornea was completely covered. The holder was slightly rotated, with the corneas maintained in a horizontal position, to ensure uniform distribution of the solutions over the entire cornea. Corneas were incubated in a horizontal position for 240 +/- 10 minutes at 32 +/- 1°C. After the incubation the solutions and the test substance were removed and the epithelium was washed at least three times with MEM with phenol red. Possible pH effects of the test substance on the corneas were recorded. Each cornea was inspected visually for dissimilar opacity patterns. The medium in the posterior compartment was removed and both compartments were refilled with fresh cMEM and the opacity determinations were performed.

4. Opacity measurement
The opacity of a cornea was measured by the diminution of light passing through the cornea. The light was measured as illuminance (I = luminous flux per area, unit: lux) by a light meter. The opacity value (measured with the device OP-KIT) was calculated.
Following the final opacity measurement, permeability of the cornea to Na-fluorescein was evaluated. The medium of both compartments (anterior compartment first) was removed. The posterior compartment was refilled with fresh cMEM. The anterior compartment was filled with 1 mL of 5 mg Na-fluorescein/ml cMEM solution. The holders were slightly rotated, with the corneas maintained in a horizontal position, to ensure uniform distribution of the sodium-fluorescein solution over the entire cornea. Corneas were incubated in a horizontal position for 90 +/- 5 minutes at 32 +/- 1°C. After the incubation period, the medium in the posterior compartment of each holder was removed and placed into a sampling tube labelled according to holder number. 360 µl of the medium from each sampling tube was transferred to a 96-well plate. The optical density at 492 nm (OD492) of each sampling tube was measured in triplicate using a microplate reader.

Results and discussion

In vitro

Irritation parameter:
in vitro irritation score
Based on Opacity and Permeability measurements
Run / experiment:
Test substance
ca. 0.7
Vehicle controls validity:
not applicable
Negative controls validity:
3.6 IVIS
Positive controls validity:
96.9 IVIS
Remarks on result:
no indication of irritation
Other effects / acceptance of results:
- The corneas treaed with the test substance and the negative control were clear post treatment where as the one treated with the positive control were cloudy. The In Vitro irritancy scores were determined to be 0.7, 3.6 and 96.9 following application of the test substance, the negative control and the positive control, respectively.

Any other information on results incl. tables

Interpretation of the results:

- Determination of the In vitro irritancy score (IVIS):

The mean opacity and mean permeability values (OD492) were used for each treatment group to calculate an in vitro score.

- The IVIS cut-off values for identifying the test substances as inducing serious eye damage (UN GHS Category 1) and test substances not requiring classification for eye irritation or serious eye damage (UN GHS No Category) are given hereafter:

< or = 3: no category,

>3 and < or = to 55: no prediction can be made,

> 55: category 1.

Based on the study results, the test substance was determined to be non-irritant to the eye.

Applicant's summary and conclusion

Interpretation of results:
other: not classified based on EU CLP criteria
Under the study conditions, the test substance was determined to be non-irritating or non-corrosive to the eye.
Executive summary:

An in vitro study was conducted to determine the eye corrosion potential of the test substance, 'mono- and di- C16 PSE, K+ and C16-18-OH', using the Bovine Corneal Opacity and Permeability (BCOP) method, according to OECD Guideline 437, in compliance with GLP. Preparation, selection and opacity reading of the corneas were performed as per guideline. Prepared corneas in triplicates were treated with each, test substance (20% w/v in sodium chloride 0.9% w/v), negative control (Sodium chloride 0.9% w/v) and positive control (20% w/v Imidazole solution in sodium chloride 0.9% w/v) substances at 32 ± 1ºC for 240 minutes. At the end of the exposure period the test substance and control substances were removed from the anterior chamber and the cornea was rinsed three times with fresh complete EMEM containing phenol red before a final rinse with complete EMEM without phenol red. A post treatment opacity reading was taken and each cornea was visually observed. Following the opacity measurement the permeability of the corneas to sodium fluorescein was evaluated. The medium from the anterior chamber was removed and replaced with 1 mL of sodium fluorescein solution (5 mg/mL). The dosing holes were plugged and the holders incubated, anterior chamber uppermost, at 32 ± 1ºC for 90 minutes. The two endpoints, decreased light transmission through the cornea (opacity) and increased passage of sodium fluorescein dye through the cornea (permeability) were combined in an empirically derived formula to generate an In Vitro Irritancy Score (IVIS). The corneas treated with the test substance and the negative controls were clear post treatment where as the one treated with the positive control was cloudy. The positive control group had an overall IVIS of 96.9. The negative control gave opacity of ≤2.4 and permeability ≤0.072, the negative control acceptance criteria were therefore satisfied. The test substance IVIS score obtained was 0.7, which was well below the threshold for non-classification. The study has met the validity criteria. Under the study conditions, the test substance was determined to be non-irritating or non-corrosive to the eye (Harlan, 2014).