TOXICOLOGY AND APPLIED PHARMACOLOGY 7, 308-319 (1965) 

Comparative Evaluation and the Influence of Various 

Factors on Eye-Irritation Scores 

A. S.WELTMAN,S. B. SPARBER,AND TANIA JURTSHUK~ 

Brooklyn College of Pharmacy, Long Island University, Brooklyn, New York, and 

St. Vincent Hospital, New York, New York 

Received April 13, 1964 

Safety-testing measures require and demand the elimination of unsafe, harmful, and 

deleterious substances from product development prior to their release for public 

consumption. Unfortunately, the development of new, and perhaps beneficial, products has been blocked temporarily or permanently by “pass-fail” type of examinations 

based on conclusions drawn from somewhat limited studies. 

The scoring procedure outlined by Draize et al. (1944) and its subsequent modification by Draize (1959) have been the methods most frequently utilized for the 

interpretation and evaluation of eye-irritation tests. Ophthalmic medications or cosmetic products, such as shampoos, likely to come in contact with the human eye, 

must of necessity pass this type or related kinds of examinations. Although, through 

the years, the Draize technique has performed an admirable function in the testing 

and preventative marketing of harmful substances, certain shortcomings inherent in 

the procedure have become evident. Recently, Russell and Hoch (1962) reported five 

somewhat diverse comparative evaluations made independently by five testing laboratories of two shampoo samples scored by the Draize test. Since each of the laboratories 

represented well-known and reputable biological testing centers, the question arises 

as to the possible cause or causes of these deviations and how such differences in 

scoring can be eliminated or explained. 

The Draize technique, which utilizes the albino rabbit, subjectively and quantitatively scores eye irritation by observing corneal, iridial, and conjunctival damage 

following instillation of O.l-ml amounts of the test material in one eye, the other 

untreated eye serving as a control. A series of 9 rabbits are usually used for each test. 

The treated eyes of 3 rabbits remain unwashed. In contrast, to observe possible prevention of injury, the treated eyes of 3 other rabbits are washed with 20 ml of lukewarm water 2 seconds after instillation and the remaining 3 rabbits at 4 seconds after 

instillation of the test material. Ocular readings are made at 24, 48, and 72 hours and 

at 4 and 7 days after treatment or as long as the injury persists. 

The actual grading process is subjective and involved; this in itself represents a 

large source for the disparities in the conclusions of various individuals scoring the 

reactions. Quantitatively, cornea& iridial, and conjunctival damage are not evaluated 

equally. Cornea1 damage, by far, possesses the greatest weighting factor based upon 

considerations of its importance to vision and its greater susceptibility to damage. 

Fully realizing the extreme difficulty in adequately devising a numerical scoring 

1 Senior resident ophthalmologist, St. Vincent Hospital. 
EVALUATION OF EYE-IRRITATION SCORES 309 

system for classifying eye damage, the investigation sought to combine with the 

Draize procedure, the simultaneous use of additional techniques involving photographic, ophthalmoscopic and histologic observations. It was hoped that procedures 

such as these would aid in the reduction of subjective errors and help in the proper 

evaluation and assessment of eye irritation and the substances capable of inducing 

such damage. The study also considers the role of population sizes, time of release, 

and other factors which may affect eye irritation scores, 

METHODS 

The shampoo preparations studied were supplied by the Malmstrom Chemical Corporation and were identified by the numbers A-65/1 and A-65/2. They were from 

the same batches submitted by Russell and Hoch (1962) to five commercial laboratories for testing by the Draize method. Their compositions are shown in Table 1. 

TABLE 1 

COMPOSTION OF SHAMPOO PREPARATION TESTED 

Shampoo preparation 

A-65/1 A-65/2 

(%) (%) 

TEA lauryl sulfated (40% solution) 50.0 50.0 

Deionized water 41.0 45.0 

Lanolin alcohol@ with 16 moles C,H,O 3.0 - 

Lanolin oil* 1.0 - 

CCOFA diethanolamidec 5.0 5.0 

100.0 100.0 

a Nimcolan@ “S’‘-Malmstrom Chemical Corporation. 

b Lantrol@-Malmstrom Chemical Corporation. 

0 Sandrol superamide lOOC-Clintwood Chemical Company. 

d Duponol wat. 

The reactions were scored according to the Draize scale with certain modifications 

at the l-, 2-, 3-, 4, and 7-day intervals. In addition, eye damage was also scored 

on the 5th day. The modifications consisted mainly in recording changes such as lack 

of luster, in noting intermediate grades or effects (i.e., l+ or 2+, etc.), and in 

attempting to determine the range and degree of subjective errors introduced by borderline evaluations on the total mean scores. Too often borderline alterations create 

personal and subjective difficulties in assigning a value to that change (i.e., whether 

to score such event with a higher or lower unit value). To assay this factor, borderline cases were recorded as minus numbers. The data were then calculated on the 

basis of high-scoring and low-scorin g estimates. For example, the borderline grade of 

minus 2 was computed as either having a number 2 or number 1 Draize value when 

mean scores were calculated. 

Twenty-eight young male albino rabbits averaging 1.96 kg were used. The rabbits 

were acclimated and housed for 1 week prior to initiation of the study in a laboratory 

maintained at 70°F. In general, a modified Draize technique was followed which 

omitted the eye-washing stages to attain maximum damage. Twenty-four of the rabbits were used as test animals; they were divided into groups of four. The procedure 

entailed the instillation of O.l-ml amounts of the respective test solution into the 
310 A. S. WELTMAN, S. B. SPARBER, AND TANYA JURTSHUK 

conjunctival sac of each eye by means of a tuberculin syringe. The eyes of all test 

and control rabbits were examined for gross defects before instillation of the test or 

saline solutions. To prevent loss or escape of the fluid from the sac, the eyelids were 

held in a closed position away from the eyeball for approximately 20 seconds. The 

opposite eye was used to compare the effects of the second sample in order that the 

effects of both solutions could be evaluated on the same individual. To avoid scoring 

errors due to possible differential reactivities and sensitivities of either the right or 

left eyes, each test preparation was instilled into 2 left and 2 right eyes of each group 

of 4 rabbits. The reactions were scored according to the Draize scale at intervals of 

1, 2, 3, 4, and 7 days. In addition, eye damage was also scored on the 5th day. The 

knowledge to score eye damage was acquired by prior visits to two testing laboratories and by consultation with the Food and Drug Administration, Washington, D. C. 

The lighting consisted of overhead fluorescent lights assisted by daylight from an 

adjacent and nearby window. The extent of eye damage was read with the unaided 

eye and with an ophthalmoscope. 

Four rabbits were used as control animals. Identical volumes of normal saline were 

administered into 2 left and 2 right eyes of the control group, the corresponding 

opposite eyes remaining untreated. All saline-treated and untreated eyes were examined and scored in a similar fashion as the test eyes. 

Four test rabbits were sacrificed daily at days 1, 2, 3, 5, and 7 by sodium pentobarbital injections administered into the ear veins of the respective rabbits. Immediately prior to autopsy, however, two photographs were taken with a Minox III B 

camera of each eye, using Kodachrome film (ASA-25). One picture was taken of 

the treated eye at rest. The second picture attempted to demonstrate the extent of 

corneal, iridial, and conjunctival damage by holding apart the upper and lower eyelids. The choice of the Minix III B camera was twofold: (a) its simplicity of operation without the need of additional devices such as close-up lenses and (b) the ease 

by which all 4 photographs of the same animal could be mounted on a conventional 

35mm frame for simultaneous projection and evaluation. 

Upon autopsy, both eyes of each animal were surgically removed, labeled, and fixed 

in Bouin’s solution. The tissues were embedded in Bioloid paraffin (56-SS”C), sectioned at 4 p, and stained with hematoxylin and eosin. Histologic observations were 

based on three slides derived from three regions of each eye. Vertical cross sections 

were prepared of the mid-region as well as extreme right and left areas of each eye. 

Every slide contained two adjacent sections taken from one of the respective areas 

being studied. 

All twenty test rabbits sacrificed on days 1, 2, 3, 5, and 7 for histologic purposes 

were released immediately following instillation of the test preparations. An additional group of 4 rabbits were held in stocks and released 1% hours after instillation 

of the test samples. Although the eyes of these rabbits were not prepared histologically, 

the animals were graded and examined in a similar fashion as the others for 7 days. 

OBSERVATIONS 

A. Extent of Personal and Subjective Errors on the Mean, Total Eye-l&at& 

Scores 

Table 2 presents the high- and low-scoring estimates of the mean total eye-irritation 

grades recorded by visual examination of the rabbits’ eyes. These estimates reveal the 
EVALUATION OF EYE-IRRITATION SCORES 311 

range of subjective error and borderline doubts on the mean, total eye-irritation scores. 

The data were compiled from an initial population of 24 test rabbits subsequently 

reduced to a sample size of 8 rabbits by the gradual autopsy procedures. 

Analyses demonstrated no appreciable or statistically significant differences between 

the effects produced by samples A-65/1 and A-65/2 whether computed on a high- or 

low-scoring basis. Furthermore, no significant differences were observed between the 

respective high-score or low-score estimates of each test solution. This serves to demonstrate the range of the differences which an individual’s subjective error can produce 

in initial scoring procedures. In this instance, the differences were relatively minimal. 

TABLE 2 

MEAN SCORES OF ALBINO MALE RABBIT EYE-IRRITATION TESTS: RESULTS COMPARE 

HIGH-SCORE AND LOW-SCORE ESTIMATES 

Parameter 

Number of rabbits 

High-score estimate 

Sample A-65/1 

Sample A-65/2 

P value (A-65/1 vs. A-65/2) 

Low-score estimate 

Sample A-65/1 

Sample A-65/2 

P value (A-65/1 vs. A-65/2) 

P values of differences between 

high- and low-score estimates 

A-65/1 (high-score vs. low-score) 

A-65/2 (high-score vs. low-score) 

1st 2nd 

24 20 

16.5 15.9 

17.4 15.1 

0.81 0.86 

13.5 13.3 

12.1 10.5 

0.66 0.49 

0.41 0.58 

0.11 0.22 

Day scored 

3rd 4th 5th 7th 

16 12 12 8 

9.8 5.3 0.8 0.0 

9.9 3.5 0.2 0.0 

0.90 0.61 0.23 - 

8.4 4.5 0.0 0.0 

9.2 2.0 0.0 0.0 

0.85 0.48 - - 

0.74 0.85 - - 

0.87 0.55 - - 

B. Estimate of Sample Size as a Factor Ajecting Mean Total Score 

As stated previously, the Draize procedure requires the testing of a minimum of 

9 rabbits observed for a total of 7 days, or longer if required. Table 3 presents the 

mean total scores compiled from 8 rabbits observed throughout the 7-day period. To 

avoid bias and to simplify calculations, in the following comparisons only the highscore estimates are tabulated. Statistical analyses of the data derived from the population of 8 rabbits again revealed no significant differences between the eye-irritation 

scores produced by the two samples. 

TABLE 3 

MEAN SCORES OF ALBINO MALE RABBIT EYE-IRRITATION TESTS: RESULTS COMPARE 

HIGH-SCORE ESTIMATES BASED ON A POPULATION OF EIGHT RABBITS 

Day scored 

Parameter 1st 2nd 3rd 4th 5th 7th 

Number of rabbits 8 8 8 8 8 8 

High-score estimate 

Sample A-65/1 17.9 18.4 6.8 4.5 0.8 0.0 

Sample A-65/2 20.9 19.4 7.3 1.8 0.0 0.0 

P value (A-65/1 vs. A-65/2) 0.70 0.90 0.90 0.42 - - 
312 A. S. WELTMAN, S. B. SPARBER, AND TANYA JURTSHUK 

Table 4 reviews and compares the mean total scores obtained from the complete 

population of 24 test rabbits, a population of 8 test rabbits and the 2 subgroup populations of 4 rabbits each. It should be noted that while one group of 4 rabbits was 

released immediately (in accord with the Draize procedure) the other group of 4 

rabbits was kept in stocks for a period of lyZ hours after instillation of the test 

substances. It is apparent that the differences and ranges of the various mean total 

scores showed a greater degree of variability and spread as the population sizes 

decreased. This was especially illustrated in the range of differences displayed by the 

TABLE 4 

SCORES OF ALBINO MALE RABBIT EYE-IRRITATION TESTS: RESULTS COMPARE 

SCORES DERIVED FROM POPULATIONS OF VARYING SAMPLE SIZES 

Day scored 

G~OUD n” 1st 2nd 3rd 4th 5th 7th 

High-score estimate 

A-65/1 (complete pop.) 

A-65/1 

A-65/1 (release delayed) 

A-65/1 (released immed.) 

A-65/2 (complete pop.) 

A-65/2 

A-65/2 (release delayed) 

A-65/2 (released immed.) 

P value (A-65/1 release delayed 

vs. released immed.) 

P value (A-65/2 release delayed 

vs. released immed.) 

* Number of rabbits. 

24-8 16.5 15.9 9.8 5.3 0.8 0.0 

8 17.9 18.4 6.8 4.5 0.8 0.0 

4 29.3 31.3 12.5 9.0 1.5 0.0 

4 6.5 5.5 1.0 0.0 0.0 0.0 

24-S 17.4 15.1 9.9 3.5 0.2 0.0 

8 20.9 19.4 7.3 1.8 0.0 0.0 

4 21.8 20.8 5.5 2.5 0.0 0.0 

4 20.0 18.0 9.0 1 .o 0.0 0.0 

0.02 0.02 0.14 - - - 

0.88 0.80 0.64 0.32 - - 

A-65/1 data. Statistical analyses of the mean total scores of the 2 subgroup populations of 4 rabbits indicated significant differences between the scores of the A-6.5/1 

series on the 1st and 2nd days (i.e., 29.3 vs. 6.5 and 31.3 vs. 5.5). No significant differences were observed between the mean total of the A-65/2 sample also based on 

a population of 4 rabbits (i.e., 21.8 vs. 20.0 and 20.8 vs. 18.0). The variability due 

to population sizes was less apparent in that series. The differences, however, between 

the values of the 2 subgroup populations of 4 rabbits causes one to reflect on timerelease factors affecting eye-score evaluations. 

C. Estimate of Time of Release as a Factor Afecting Mean Total Scores 

A question requiring resolution is whether the vigorous eye-rubbing and pawing 

activities of a treated rabbit can aggravate and cause undue damage above and beyond 

that induced by the test substances. In one instance, a puncture laceration was noted 

on the upper eyelid of a test rabbit which had been released immediately. 

Table 5 presents the effects of immediate versus delayed release of the rabbits as 

a factor influencing eye-irritation scores. The values were obtained by totaling the 

combined scores of 8 eyes of the 4 rabbits treated and released immediately as compared to the scores obtained from the 8 eyes of 4 rabbits immobilized in stocks for 

1% hours. To increase sample size a liberty was taken in combining the A-6.5/1 and 
EVALUATION OF EYE-IRRITATION SCORES 313 

A-65/2 data in view of the absence of any statistically significant differences between 

the alterations produced by the 2 solutions on the basis of the complete population 

analyses. The data indicated that, in general, a lesser degree of eye irritation was 

observed in the rabbits released immediately versus those immobilized by the stocks. 

In some instances, these differences approached statistical levels of significance as 

shown by the P values on the lst, 2nd, and 4th days. It should be recalled that 

although significant differences were observed in the A-65/1 series on the 1st and 

2nd days (Table 4, n=4) none were noted in the comparable A-65/2 group. Further 

TABLE 5 

SCORES OF ALBINO MALE RABBIT EYE-IRRITATION TESTS: RESULTS COMPARE 

EFFECTS OF DELAYED SCORES vs. IMMEDIATE RELEASE 

Day scored 

Group ian 1st 2nd 3rd 4th 5th 

High-score estimate 

Delayed release 8 25.5 26.0 9.0 5.8 0.8 

Immediate release 8 13.3 11.8 5.0 0.5 0.0 

P value (delayed 

vs. immed. release) 0.10 0.06 0.43 0.10 - 

a Number of observations: 8 eyes of 4 rabbits. 

7th 

0.0 

0.0 

studies are therefore required to determine whether these findings represent chance 

occurrence due to small population sizes or a demonstration of the beneficial effects 

which eye-rubbing may cause by stimulating the lacrimating gland secretions to wash 

the treated eyes. This would seemingly counteract the danger of injuries or irritations 

caused by the clumsy, pawing activities of the rabbits immediately following instillation of a sample to the rabbits’ eyes. 

In general, histologic examination between control and the variously treated eyes 

revealed no substantial differences between the effects of either of the two test substances on the microscopic structure of the treated eyes. Moreover, a fine degree of 

correlation and correspondence was noted between the eye-irritation scores determined 

at the time of sacrifice and the degree of histologic damage. Primarily, all the observed 

histologic alterations were limited to the cornea, specifically the stratified squamous 

epithelium and the substantia propria layers. No apparent involvements were found 

either in the iris or in the choroid and retinal layers. 

The stratified epithelial layers of the normal rabbit cornea consists of one layer 

of columnar cells located beneath 3 to 5 rows of nonkeratinizing polyhedral and 

squamous cells. Posteriorly, one finds the Bowman’s membrane followed by the relatively thick substantia propria composed of modified connective tissue, the Descemet’s 

membrane, and lastly a single layer of endothelial cells. The epithelium layer of the 

bulbar conjunctiva merges indistinguishably with that of the cornea at the region 

of the limbus (Prince et al., 1960). 

Although approximately one-third of the eyes treated by either of the two substances appeared histologically normal, approximately two-thirds of the treated eyes 

showed considerable erosion in the stratified squamous layers of the cornea during the 

first 3 days following instillation of the test preparations. The damaged eyes revealed 

little or no stratified squamous epithelial cells. Accompanying this epithelial erosion, 
314 A. S. WELTMAN, S. B. SPARBER, AND TANYA JURTSHUK 

one found substantial increases in leucocytic and lymphoid cellular infiltrations of the 

substantia propria. The progressive regenerative and repairing capacities of the cornea 

were demonstrated however by the microscopic observations which revealed that by 

the 5th day only one of the treated eyes showed remnants of slight damage to the 

stratified squamous epithelium. By the 7th day, all the eyes treated by both substances were histologically normal in appearance. 

The photographic plates (Figs. 1-S) illustrate the extent of the structural changes, 

epithelial erosion, and leucocytic infiltration caused by addition of either of the 2 

samples to the eyes of rabbits. The plates further illustrate the regenerative repair 

of the epithelial layers by the 5th and 7th days as compared to the normal saline or 

untreated eyes. 

Examination of the transparencies demonstrated likewise that the external, physical 

appearance of the test and control eyes corresponded to the condition shown by the 

various histologic plates. The test solutions primarily produced alterations in the 

FIG. 1. Longitudinal section of cornea of rabbit sacrificed at the 24-hour period after treatment 

with solution A-65/1. Section illustrates erosion and loss of stratified epithelial layers with dense 

leucocytic infiltration in the substantia propria. Hematoxylin and eosin. Magnification: X 400. 

FIG. 2. Low power magnification of longitudinal section of cornea of rabbit sacrificed 3 days 

after treatment with solution A-65/2. Section demonstrates partial regenerative repair of epithelial 

layers with persistent dense leucocytic infiltration in the substantia propria. Hematoxylin and eosin. 

Magnification: X 100. 
315 

FIG. 3. High power (X 400) magnification of Fig. 2. 

FIG. 

A-65/1 

dence 

x 400. 

4. Longitudinal section of cornea of rabbit sacrificed 5 days after treatment with solution 

. Section illustrates relatively normal appearance of epithelial layers with some slight eviof leucocytic infiltration in the substantia propria. Hematoxylin and eosin. Magnification: 

FIG. 5. Low power magnification of longitudinal section of cornea of rabbit sacrificed 7 days 

after t reatment with solution A-65/1. Section demonstrates normal appearance of epithelial layers 

and th ,e absence of leucocytic infiltration in the substantia propria. Hematoxylin and eosin. Magnificati on: X 100. 
316 A. S. WELTMAN, S. B. SPARBER, AND TANYA JURTSHUK 

FIG. 6. High power (X 400) magnification of Fig. 5. 

FIG. 7. L sow power magnification of longitudinal section of cornea of sali 

demor istra rtir 4 normal appearance of epithelial layers and substantia propria. 

eosin. Ma gni fica rtion: X 100. 

ne h-treated con! .rol 

H [ematox] 7lin a .nd 

FIG. 8. High power (X 400) magnification of Fig. 7. 
EVALUATION OF EYE-IRRITATION SCORES 317 

conjunctiva and discharges from the eyes of treated rabbits. By the 5th and 7th days 

no permanent damage was observed in any of the corneas and eye discharge appeared 

normal. 

Analyses of the ophthalmoscopic observations revealed that the two test samples 

had little or no effect on the internal structure of the rabbits’ eyes. The fundi, as 

well as the crystalline lenses, were grossly normal in appearance and seemed unaffected 

by the test compounds. However, in some instances, there was a certain degree of 

difficulty in obtaining clear visualization of the fundus of the retina. The degree of 

difficulty corresponded with and showed a positive correlation with the total mean 

and cornea1 scores of the various test animals in much the same fashion as did the 

histologic observations. 

DISCUSSION 

It is evident from the data that both substances compare favorably and almost 

equally alike with regard to their eye-irritation properties. The Draize test, the ophthalmoscopic, photographic, and histologic observations revealed that the extent or 

lack of damage caused by either of the two samples ranged within the same general 

category. Recently, Kay and Calandra (1962) have presented a method for the interpretation of eye-irritation scores based on the Draize technique. Use of their empirical 

method aided in the evaluation of both samples as preparations possessing mildly 

irritating properties. 

However, the data do demonstrate or suggest that personal error, sample size, and 

time of release can or may affect total mean scores. Although personal scoring or 

subjective errors were found to have a relatively minor influence (the present scores 

being based on the simultaneous evaluations and agreement by three individuals), 

this study cannot rule out the possibility that the variations between the scores of 

differently trained individuals from two laboratories may be considerable. Such instances would serve to emphasize the necessity of additional detailed standardization 

of the Draize technique to permit greater uniformity of individual evaluation and 

assessment of eye damage. 

The study similarly demonstrates that depending on sample sizes one can have considerable differences between the total mean scores of various test groups (i.e., groups 

of 4 vs. 8 vs. 24). Statistical analyses have amply demonstrated the greater validity 

of values based on samples of sufficient population sizes. Further enlargement of the 

number of rabbits used in the standard Draize method would be helpful in avoiding 

the “pass-fail” type of errors possible by chance occurrence when small populations 

are employed. 

Concerning the factor of time of release, additional investigations are required to 

determine the beneficial or deleterious role which either early or late release may 

have on eye-irritation scores. Cursory examination always showed that within minutes 

following release (delayed or immediate) the regions and hair surrounding the eyes 

acquired a wet and matted appearance and the eyes appeared more inflamed and 

redder. Whether early release aids in the washing out or the dilution of the substances 

or whether the vigorous, unrestrained and clumsy pawing activity in the vicinity of 

the eyes can aggravate damage requires further analysis. The present evidence would 

indicate that on the whole, early release had ultimately a beneficial effect, perhaps 
318 A. S. WELTMAN, S. B. SPARBER, AND TANYA JURTSHUK 

attributable to eye-washing, although the sample size in the present study was small. 

If so, the habits of different laboratories concerning the time of release of the test 

animals could have considerable influence on total mean scores as well as between the 

scores of different laboratories. 

Possibly the greatest variable has been relatively neglected, that of the animal itself. 

Unfortunately, rabbit strains do not have the uniformity and standardization of strains 

of other species of laboratory animals, and unfortunately the breeding facilities of 

various farms supplying rabbits are far from satisfactory. Age, sex, and strain differences can affect the resistance of laboratory animals to either chemical or physical 

states of stress. 

To illustrate, certain strains of mice and rats are more prone to audiogenic seizures 

(Hamburgh and Vicari, 1960 ; Finger, 1947). Similarly, differences in seizure-susceptibility frequencies have been reported both on an age (Ginsburg and Hovda, 1947; 

Maier and Glaser, 1942), and sex (Ginsburg and Hovda, 1947; Finger, 1943) basis 

in mice and rats. 

Probably, in many instances, the difficulties in obtaining healthy rabbits from acceptable breeding farms might cause testing laboratories to overlook or underate sex, 

age, and strain difference factors. Yet, influences such as these may well be the prime 

reason for the diverse scores of different testing laboratories, as for example, those 

reported by Russell and Hoch (1962). 

A serious deficiency arises, therefore, in that the Draize procedure does not necessarily stipulate age, sex, or strain requirements other than that the animals be albino 

rabbits. Here, again additional standardization is required. A truly severe and critical 

procedure would entail the testing of animals belonging to the more susceptible sex 

and at their most susceptible age level. 

In attempting to interpret the usefulness of photographic, ophthalmoscopic and 

histologic methods in assessing eye-irritation damage, the mildly irritating nature of 

the present two test samples limited the observable severity of eye damage. However, 

the techniques can be invaluable adjuncts to standard Draize test procedures: 

1. The photographic method can permanently record the external appearance and 

physical state of the eye at any period within certain limits. 

2. Ophthalmoscopic techniques can aid in prompt visualization of retinal damage. A 

more precise and invaluable tool is the slit-lamp ophthalmoscope. This instrument 

determines not only the location, extent, and depth of corneal, iridial, lens, and retinal 

damages, but also changes in the anterior and posterior chambers of the eyes. 

3. Histologic procedures can fully ascertain and permanently record the structural 

damage done to the tissues, layers, and cells of the eyes. 

The authors recognize that these additional techniques could contribute materially 

toward increasing the cost of proving and demonstrating the value of a substance. On 

the other hand, the techniques could materially aid in granting a truer perspective of 

the value of a new product that ordinarily might have been withdrawn from development solely on the basis of premature conclusions on eye irritation based on insufficient tests. The importance of fully determining the damaging potentialities of any 

new product must not be underestimated. 
EVALUATION OF EYE-IRRITATION SCORES 319 

SUMMARY 

This study employed ophthalmoscopic, photographic, and histologic techniques as an adjunct to 

standard Draize procedures in interpreting and evahrating the degree of eye irritation produced by 

two solutions on the cornea, iris, and conjunctivae of rabbits’ eyes. 

Although ophthalmoscopic examinations revealed no evidence of retinal or internal damage, 

histologic observations, in some instances, demonstrated considerable erosion and loss of the 

stratified epithelial layers with evidence of dense leucocytic infiltration in the substantia propria 

of the cornea. By the 5th and 7th days, however, all treated eyes appeared histologically normal. 

The various data indicated that there were no significant differences in the degree of eye irritation 

caused by either preparation and that the solutions possessed properties of a mildly irritating 

nature. Certain inadequacies in obtaining a correct evaluation of eye irritation by the Draize technique were noted. In particular, the influence of such factors as subjective and personal error, 

sample size, time of release as well as age, sex, and strain differences of rabbits were discussed. It 

is believed that further standardization and modification of the Draize procedure is required to 

eliminate discrepancies between the scores of individual testing laboratories as well as differences 

between the mean scores of two or more runs of the same preparation. 

REFERENCES 

DRAIZE, J. H. (1959). Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics. 

Assoc. of Food and Drug Officials of the U.S., pp. 49-52. Editorial Committee, Baltimore, 

Maryland. 

DRAIZE, J. H., WOODARD, G., and CALVERY, H. 0. (1944). Methods for the study of irritation 

and toxicity of substances applied topically to the shin and mucous membranes. /. Pharm. Exptl. 

Therap. 92, 377. 

FINGER, F. W. (1943). Factors influencing audiogenic seizures in the rat. J. Camp. Psychol. 36, 

227-232. 

FINGER, F. W. (1947). Convulsive behavior in the rat. Psychol. Bull. 44, 201-248. 

GINSBURG, B. E., and HOVDA, R. B. (1947). On the physiology of gene controlled audiogenic 

seizures in mice. Anat. Record 99, 621. 

HAMBURG=, M., and VICARI, E. (1960). A study of some physiological mechanisms underlying 

susceptibility to audiogenic seizures in mice. J. Neuropathol. Exptl. Neurol. 19, 461-472. 

KAY, J. H., and CALANDRA, J. C. (1962). Interpretation of eye irritation tests. J. Sot. Cosmetic 

Chemists 13, 281. 

MAIER, N. R. F., and GLASER, N. M. (1942). Studies of abnormal behavior in the rat. J. Comp. 

Psychol. 34, 23-28. 

PRINCE, J. H., DIESEM, C. D., EGLITIS, I., and RUSKELL, G. L. (1960). Anatomy and Histology 

of the Eye and Orbit in Domestic Animals. Thomas, Springfield, Illinois. 

RUSSELL, K. L., and HOCH, S. G. (1962). Product development and rabbit eye irritation. Proc, 

Sci. Sect. Toilet Goods Assoc. 37, 27.