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Toxicological information

Eye irritation

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Administrative data

Endpoint:
eye irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
03 October 2016 to 11 November 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 438 (Isolated Chicken Eye Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Details on test material:
- Appearance/physical state: Tan waxy solid
- Storage conditions: Room temperature in the dark

Test animals / tissue source

Species:
chicken
Strain:
other: COBB 500 in Experiment I and ROSS 308 in Experiment II
Details on test animals or tissues and environmental conditions:
- Source: TARAVIS KFT, 9600 Sárvár, Rábasömjéni út.129., Hungary

Test system

Controls:
yes, concurrent positive control
yes, concurrent negative control
Amount / concentration applied:
30 mg
Duration of treatment / exposure:
10 seconds
Number of animals or in vitro replicates:
Three each in experiments I and II
Details on study design:
INTRODUCTION
- The Enucleated Eye Test with isolated eyes of chickens has been recognised as a valuable alternative to the Draize eye irritation test regarding ocular corrosivity or severe eye irritancy testing, because it represents a test system nearest to the in vivo test, without the need to use live animals. In the Isolated Chicken Eye Test (ICET) the
test compound is applied in a single dose onto the cornea of isolated eyes, which are obtained from slaughter animals.
- This method can provide detailed information about the effects of test items on the cornea, and can be used to identify chemicals not requiring classification for eye irritation, or for serious eye damage, as defined by the UN GHS (UN GHS nonclassified or UN GHS Category 1). The test is described in OECD No. 438 and is approved by international regulatory agencies as a replacement for the identification of non-irritant, corrosives/severe irritants in the in vivo Rabbit Eye Assay (OECD No. 405).

TEST ITEM SOLUBILITY AND FORMULATION
- The solubility of the test item in physiological saline was tested prior to the experiment (30 mg test material in 1 mL physiological saline). The test item did not dissolve in physiological saline.
- The test item was applied in its original form (although the test item was pulverized into smaller pieces).

SUBSIDIARY MATERIAL
- Fluorescein 10 % (w/v) (Alcon; Lot 250817F; Expiry date 31 May 2017; Room temperature storage conditions).
- This material was mixed with physiological saline (Manufacturer: B. Braun Pharmaceuticals SA, Lot number: 61461Y05-1, Expiry date: March 2019) to achieve the final concentration of 2% (w/v).
- The resulting solutions were stored at room temperature (Dispensary code: S43108, Expiry date: 12 October
2016 in Experiment I; Dispensary code: S43111, Expiry date: 24 November 2016 in Experiment II).

CHICKEN HEADS COLLECTION AND TRANSPORT
- Chicken heads were collected after slaughter in a commercial abattoir from chickens (approximately 7 weeks old) which are used for human consumption. Heads were collected by a slaughter house technician and heads transported to CiToxLAB Hungary Ltd. at ambient temperature at the earliest convenience.
- After collection, the heads were inspected for appropriate quality and wrapped with tissue paper moistened with saline, then placed in a plastic box which was closed (4-5 heads per box). The heads were received at CiToxLAB Hungary Ltd. and processed within approximately 2 hours of collection.

SELECTION OF EYES
- After removing the head from the plastic box, it was put on soft paper.
- The eyelids were carefully cut away with scissors, avoiding damaging the cornea.
- One small drop of 2 % (w/v) fluorescein solution was applied onto the cornea surface for a few seconds and subsequently rinsed off with 20 mL physiological saline. Then the fluorescein treated cornea was examined with a hand-held slit lamp or slit lamp microscope, with the eye in the head, to ensure that the cornea was not damaged. - If the cornea was in good condition, the eyeball was carefully removed from the orbit.

PREPARATION OF EYES
- The eye ball was carefully removed from the orbit by holding the nictitating membrane with surgical forceps, while cutting the eye muscles with bent scissors. Care was taken to remove the eyeball from the orbit without cutting off the optical nerve too short. The procedure avoided pressure on the eye while removing the eyeball from the orbit, in order to prevent distortion of the cornea and subsequent corneal opacity.
- Once removed from the orbit, the eye was placed onto damp paper and the nictitating membrane was cut away with other connective tissue. The prepared eyes were kept on the wet papers in a closed box so that the appropriate humidity was maintained.

EYE EXAMINATION AND ACCLIMATISATION TIME
- The prepared eye was placed in a steel clamp with the cornea positioned vertically with the eye in the correct relative position (same position as in the chicken head) avoiding too much pressure on the eye by the clamp. Because of the relatively firm sclera of the chicken eyeball, only slight pressure was needed to fix the eye properly. The clamp with the eyeball was transferred to a chamber of the superfusion apparatus. The clamp holding the eye was positioned in such a way that the entire cornea was supplied with physiological saline solution dripping from a stainless steel tube, at a rate of approximately 3-4 drops/minute or 0.1 to 0.15 mL/minutes. The door of the chamber was closed except for manipulations and examinations, to maintain temperature and humidity.
- The appropriate number of eyes were selected and after being placed in the superfusion apparatus. There they were examined again with the slit lamp microscope to ensure that they were in good condition. The focus was adjusted to see clearly the physiological saline which was flowing on the cornea surface. Eyes with a high baseline fluorescein staining ( > 0.5) or corneal opacity score (> 0.5) were rejected. The cornea thickness was measured and any eye with cornea thickness deviating more than 10 % from the mean value for all eyes, or eyes that showed any other signs of damage, were rejected and replaced. If the selected eyes were appropriate for the test, the acclimatisation started and was conducted for approximately 45 to 60 minutes. The chambers of the superfusion apparatus were at controlled temperature (32 ± 1.5°C) during the acclimatisation and treatment periods.

IDENTIFICATION
- The eyes were identified by chamber number, marked on the door of the chamber.

BASELINE ASSESSMENTS
- At the end of the acclimatisation period, a zero reference measurement was recorded for cornea thickness and opacity to serve as a baseline (t=0) for each individual eye.
- The cornea thickness of the eyes should not change by more than 5% within the -45 min and the zero time.
- No changes in thickness (0.0%) were observed in the eyes.
- Following the equilibration period, the fluorescein retention was measured.
- Baseline values were required to evaluate any potential test item related effect after treatment.
- All eyes were considered to be suitable for the assay.

TREATMENT
- After the zero reference measurements, the eye (in its retainer) was removed from the chamber, held in a horizontal position and the test item was applied onto the centre of the cornea, taking care not to damage or touch the cornea.
- Test item (30 mg) was applied was applied onto the entire surface of the cornea attempting to cover the cornea surface uniformly with the test item, taking care not to damage or touch the cornea.
- In each experiment, the negative control eye was treated with 30 μL of physiological saline; positive control eyes were treated with 30 mg powdered imidazole.
- One eye was treated with physiological saline, three eyes with the test item and another three eyes with powdered imidazole in each experiment.

TEST ITEM REMOVAL
- The time of application was noted, then after an exposure period of 10 seconds from the end of the application the cornea surface was rinsed thoroughly with 20 mL physiological saline solution at ambient temperature, taking care not to damage the cornea but attempting to remove all residual test material if possible.
- Additional gentle rinsing with 20 mL saline was performed after treatment and at each time point when the test item or positive control material remaining on the cornea was observed.
- The test item treated eyes (where the test item was stuck on the cornea surfaces) were rinsed additional gentle rinsing at least 2x20 mL saline after treatment in each experiment.

OBSERVATION AND ASSESSMENT OF CORNEAL EFFECTS
- The control eyes and test eyes were evaluated pre-treatment and at approximately 30, 75, 120, 180 and 240 minutes after the post-treatment rinse. Minor variations within approximately ± 5 minutes were considered acceptable.
- Corneal thickness and corneal opacity were measured at all time points.
- Fluorescein retention was measured on two occasions, at baseline (t=0) and approximately 30 minutes after the post-treatment rinse, using a Haag-Streit BP 900 slit-lamp microscope.

EVALUATION
- Corneal swelling was calculated using the formulae CS at time t = (CT at time t – CT at t=0 / CT at t = ) x 100 and Mean CS at time t = (FECS at time t + SECS at time t + TECS at time t) / 3 where CS = cornea swelling; CT = cornea thickness; FECS at time t = first eye cornea swelling at a given time point; SECS at time t = second eye cornea swelling at a given time-point; TECS at time t = third eye cornea swelling at a given time-point.
- Small negative numbers for swelling (0 to -5%) following application are evaluated as class I. Large negative numbers (> 12% below control) are probably due to erosion and indicate a severe effect (scored as class IV). Cases of values of -5% to -12% are evaluated on a case by case basis but in the absence of other findings do not indicate a severe effect (class II).
- Cornea opacity was calculated according to the formulae ACO at time t = CO at time t – CO at t=0 and Mean ΔCO max = (FECO max 30 min to 240 min + SECO max 30 min to 240 min + TECO max 30 min to 240 min) / 3 where CO at time t = cornea opacity at (30, 75, 120, 180 and 240) minutes after the post treatment rinse; CO at t=0 = baseline cornea opacity; ΔCO at time t = difference between cornea opacity at t time and cornea opacity baseline; FECO = first eye cornea opacity; SECO = second eye cornea opacity; TECO= third eye cornea opacity; max 30min to 240min = maximum opacity of the individual eye at 30 to 240 minutes minus baseline cornea opacity of the individual eye.
- Fluorescein retention was calculated according to the formulae ΔFR at time t = FR at time t – FR at t=0 and Mean ΔFR = (FEFR 30 min + SEFR 30 min + TEFR 30 min) / 3 where FR at time t = fluorescein retention at 30 minutes after the post-treatment rinse; FR at t=0 = baseline fluorescein retention; ΔFR at time t = difference between fluorescein retention at t time and fluorescein retention baseline; FEFR = first eye fluorescein retention at 30 minutes after the post-treatment rinse minus baseline fluorescein retention; SEFR = second eye fluorescein retention at 30 minutes after the post-treatment rinse minus baseline fluorescein retention; TEFR = third eye fluorescein retention at 30 minutes after the post-treatment rinse minus baseline fluorescein retention.

RETENTION OF CHICKEN EYES
- At the end of the procedure, the corneas from the eyes were carefully removed from the eyes and placed individually into labelled containers of preservative fluid (10% neutral buffered formalin, Manufacturer: Reanal, Batch number: KTM15711, Expiry date: April 2018) was used for potential histopathology and stored at room
temperature.

Results and discussion

In vitro

Resultsopen allclose all
Irritation parameter:
other: overall ICE class
Run / experiment:
Experiment I
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: 3 x I
Irritation parameter:
other: overall ICE class
Run / experiment:
Experiment II
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: 3 x I
Other effects / acceptance of results:
TEST ITEM
- Individual data for Experiments I and II are shown in Tables 1.1 and 1.2 (see Appendix 1, attached).
- The mean values of the treated eyes for maximum corneal thickness change, corneal opacity change and fluorescein retention change are attached for Experiments I and II.
- The conclusion on eye irritancy was based on the OECD guideline quantitative assessments, shown in Appendix 2 (attached).
- Details of data interpretation for Isolated Chicken Eye (ICE) Class are given in Appendix 2 and 3 (attached). The mean maximum corneal swelling up to 240 min, the mean maximum corneal opacity and the mean fluorescein retention ICE classes are used for EC and GHS classification.
- The test item showed no significant corneal effect in the first experiment. As the test item was solid, the negative results were confirmed by a second experiment according to the recommendations of the OECD no. 438 guideline. - The second experiment confirmed the negative results. However, test item stuck on two cornea surfaces at 240 minutes after the post-treatment rinse in the first experiment. Based on our experience for some cases where test item adheres to the cornea in vitro, this can result in severe irritation in vivo (probably due to mechanical effects of abrasive particles stuck to the cornea). However, in this case only a minimal amount of test item was observed by the end of the observation period, thus this fact was considered not to adversely affect the results and study interpretation. Therefore, based on these in vitro eye irritation tests in isolated chicken eyes, the test item was
non-irritant, UN GHS Classification: No Category.
- A summary table showing UN GHS classification information relating to the test item is attached.

POSITIVE CONTROL
- Individual data for Experiments I and II are shown in Tables 1.3 and 1.4 (see Appendix 1, attached).
- The positive control (Imidazole) was classified as severely irritating, UN GHS Classification: Category 1 (see results for Experiments I and II, attached).

NEGATIVE CONTROL
- Individual data for Experiments I and II are shown in Tables 1.5 and 1.6 (see Appendix 1, attached).
- The negative control Physiological saline was classified as non-irritating, UN GHS Classification: Non-classified. (see results for Experiments 1 and II, attached).

VALIDITY OF THE TEST
- Historical control data are attached.
- The results from all eyes used met the quality control standards. The negative control and positive control results were within the historical data range in experiment. This experiment was considered to be valid.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Based on the in vitro eye irritation assays in isolated chicken eyes, the test item was determined to be non-irritant, UN GHS Classification: No Category.
Executive summary:

GUIDELINE

An in vitro eye irritation study of the test item was performed in isolated chicken eyes. The irritation effects of the test item were evaluated according to the OECD No. 438 (26 July 2013).

 

METHODS

After the zero reference measurements, the eye was held in horizontal position and 30 mg test item was applied onto the centre of the cornea in such a way that the entire surface of the cornea was covered. After 10 seconds, the surface was rinsed with physiological saline. Positive control eyes were treated with 30 mg powdered Imidazole. The negative control eye was treated with 30 μL of physiological saline (0.9% (w/v) NaCl solution). In the study, three test item treated eyes, three positive control treated eyes and one negative control treated eye were examined.

 

RESULTS

Results from all eyes used in the study met the quality control standards. The negative control and positive control results were in good correlation with the historical control data. Thus, the experiment was considered to be valid.

 

As the test item was solid, the observed negative result of the first experiment was confirmed by a second experiment.

 

Experiment I: No significant corneal swelling (mean ≤5%) was observed during the four-hour observation period on test item treated eyes. Cornea opacity change (severity 0.5) was observed on three eyes. Fluorescein retention change (severity 0.5) was noted on one eye. Minimal amount of test item was stuck on two cornea surfaces at 240 minutes after the post-treatment rinse.

 

Experiment II: No significant corneal swelling (mean ≤5%) was observed during the four-hour observation period on test item treated eyes. Cornea opacity change (severity 0.5) was observed on one eye. Fluorescein retention change (severity 0.5) was noted on three eyes.

 

CONCLUSION

Based on the in vitro eye irritation assays in isolated chicken eyes, the test item was determined to be non-irritant, UN GHS Classification: No Category.