Keeler Practitioner Ophthalmoscope 2.8V Dry Cell Battery With a high lens and filter range, the practitioner ophthalmoscope id ideal for the primary care specialist. • The positive may wheel lens control allows you to click through lens powers from +40 to -25D allowing detailed examination of the ocular structures, and ease of use for spectacle wearers • The ingeral soft brow allows for easy positioning and protects your lenses if you are a spectacle wearer • Macular - reduces excessive papillary reaction and patient discomfort • Slit - to determne retinal elevations, depressions and anterior chamber depth • Fixation cross - for assessment of the degree and direction of eccentric fixation • Cobalt blue - for the detention and examination of corneal scars and abrasions • Red free - used to examine blood vessels in fine detail.