189, JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS eases in man. Through very carefully controlled experiments in animals, in- vestigators have gained a tremendous amount of knowledge which has been ultimately useful in the care and treatment of diseases in man. In the area of ophthahnology, animal test models are also an integral part of the study of disease processes of the eye. In this laboratory, in addition to the study of mechanisms of conditions similar to clinical eye diseases, each new therapeutic drug entity or cosmetic proposed for human use is carefully eval- uated in animals as an extra measure of consumer protection. And, as the scope of regulatory requirements broadens, other agents not specifically de- signed for direct ocular application but for periocular use must now be evalu- ated for effects on this sensitive organ. Ophthalmic, dermatologic, and cosmet- ic formulations are routinely evaluated in our laboratories for their potential to induce ocular damage in animal species prior to use in man. The use of the slit lamp as an aid in examination allows the investigator to make fine distinc- tions of ocular pathology. Thus, the investigator is able to make better judg- ments for selection of a formulation which possesses a low potential for ocular irritation. Of primary concern, regardless of the categories of interest, is that the in- vestigator is ultimately faced with documentation and quantitation of the experimental results. Of course, the animal investigator usually has an option not available to the clinicJan of terminal histopathologic ocular examination. Indeed, this is an extremely valuable tool but is not always optimal for follow- ing the course of a disease process. Therefore, appropriate methods for fol- lowing the disease and recording changes must be developed to evaluate in situ pathology. OCULAR IRRITATION GRADING SCALES In 1944, Draize and others (1) devised a system for evaluating ocular le- sions induced by topical applications of test chemicals (Table I). The Draize scale has thus become the mainstay for the evaluation of ocular lesions in ex- perimental animals and has been widely utilized as the basis for devising oth- er grading systems. Basically, the Draize scale is a subjective macroscopic evaluation of the eonjunetiva, cornea, and iris. Although originally intended for use in albino rabbits, modifications will allow use in other animal species and in specialized situations. As an outgrowth of the original Draize scoring procedure, our group as well as others have adopted the use of the slit lamp to the routine procedures of examination of experimental animal eyes. The slit lamp, developed by Gullstrand in 1911, was originally an exclusive re- search device which has now evolved to an indispensable tool for the ophthal- mie practitioner. We have found that this instrument is also an invaluable aid for the examination of experimental animal eyes in that gross as well as mi- nute pathological changes may be identified and subjectively quantitated in an in situ situation. With the development of the photographic capabilities

EVALUATION BY SLIT-LAMP TECHNIQUES 183 Table I Draize Scale" for Scoring Ocular Lesions _ Cornea A. Opacity--degree of density ............. Grades 0- 4 B. Area of cornea involved ................ Grades 1 -- 4 A X B X 5 Maximum score -- 80 Iris A. Values .............................. Grades 0- 9, A X 5 Maximum score -- 10 Conjunctiva A. Redness ............................. Grades 0- 3 B. Chemosis ............................ Grades 0- 4 C. Discharge ........................... Grades 0- 3 (A q- B q- C) X 9, Maximum score -- 9,0 The total score for the eye • sum ot• all scores øThe Draize scale has been abbreviated in this table. Consult Draize et al. (1) for com- plete table. now possible with the slit lamp, these induced pathological changes in the experimental animal eye may now be recorded in stereopsis by the inves- tigator. As a basis for establishing grading scales, the investigator must become completely familiar with the normal animal eye as viewed with the slit lamp. Then appropriate numerical scores may be arbitrarily assigned between the normal eye and that which the investigator considers maximal pathologic change for any given test situation. Although similar to the original Draize method of subjective scoring, as previously stated, minute changes may be identified and quantitated which could not be detected by macroscopic examination. We have found this method extremely valuable with regard to examination of the cornea, anterior &hamher, iris, and lens. Due to anatomical features in many animal species, the Draize method of scoring conjunctival pathology has proved satisfactory for quantitating reaction in this ocular tissue. Although slit-lamp examination is readily adaptable to various animal spe- cies, for the purposes intended in this communication, comments are confined to the albino rabbit eye to enable comparison to the original Draize method. STUDY OF ALBINO i•ABBIT EYE Cornea The rabbit cornea is examined first (Table II). With the aid of the slit lamp one may easily visualize three distinct layers: epithelium, stroma, and endothelium. Contrary to the Draize method, one is capable of separately examining each layer in most instances. With the aid of fluorescein staining, epithelial defects may be quantitated with regard to both intensity and area