J. Soc. Cosmet. Chem., 24, 163-180 (March 2, 1973) Slit-Lamp Examination of Experimental Animal Eyes. I. Techniques of Illumination and the Normal Animal Eye THOMAS O. McDONALD, M.S.,* HENRY A. BALDWIN, B.S.,* and C. HAROLD BEASLEY, M.D.* Presented May 25, 1972, Seminar, Los Angeles, Calif. Synopsis--The SI,IT LAMP is an indispensable tool for the ophthalmologist and for the ex- perimental researcher utilizing the eye. The purpose of this paper is to describe briefly the slit lamp and accessories, disCriss uses and limitations of the type of slit-lamp ILLUMI- NATION for visualization of the eye, and describe the normal:ANIMAL EYE. Since the use of the slit lamp can be easily mastered, its use in evaluating the eye in experimental studies should be irnplement6d. Critical observation of the eye utilized in OCULAR IRRI- TATION studies for pharmaceuticals, cosmetics, and other formulations can be accom- plished with the aid of the slit lamp. INTRODUCTION The slit-lamp microscope is an instrument of this century (1, 2). It has evolved from an exclusive research device to an indispensable tool for the ophthalmic practitioner. Recently it has been adapted for use in the experi- mental ophthalmic area. The slit lamp can become a useful tool for evaluation of formulations for ocular damage in animal test models. Since many cosmetic formulations may * Science and Technology Division, Alcon Laboratories, Inc., P.O. Box 1959, Fort Worth, Tex. 76101. + 1212 West Presidio, Fort Wc'rth, Tex. 163

164 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS accidentally be introduced into the eye, the cosmetics should be and are rou- tinely tested in animal eyes. The slit lamp becomes a tool which allows the investigator to make fine distinctions for ocular damage and between two or more comparative cosmetic materials. This laboratory is part of an ophthalmic pharmaceutical manufacturing company as such, the majority of the experimental and clinical research is in the ophthalmology area. Expertise has been developed in utilizing the slit lamp for the experimental ocular studies. Over the years, a grading system has been developed for toxicological and pharmacological evaluations of experi- mental studies in animals. This grading system depends upon the utilization of the slit-lamp biomicroscope as an indispensable experimental tool. There- fore, the gencral purpose of this and the next report is to present the uses and applications of the slit lamp in the experimental laboratory. The purpose of this endeavor is to describe the slit lamp and its use, and to illustrate the types of illumination employed. Figure 1. Slit • .... -..• :. i -51.. .•:• •:.• -: •::. . ß ..• : .... :•.: ....... •. '•.. -•$ . • .• .:: - ...... ......... •... . .• ..• ::: .... .•)•:• t-•': •..•? ......... •.'-... •$. : - •.. .-•. •..-• lamp with corneal microscope (a) •d s•t filuminator (b). (CouResy of Bausch and Lomb)