DISEASES OF THE RETINA AND CHORIOID 125 



a plus or minus spheric lens. The numbers of the plus 

 lenses are usually white, while those of the minus lenses 

 are red. The examiner's eyes should both be open, 



Fig. 30.— Loring's ophthalmoscope, with tilting mirror, complete disk 

 of lenses from — i to -8 and o to +7, and supplemental quadrant con- 

 taining ±0.5 and ±16 D. This affords 66 glasses or combinations from 

 + 23 to— 24D. 



and the accommodation relaxed, as in viewing objects 

 through the microscope. The indirect examination is 

 made at a greater distance from the animal's eye, and 



