Halogen HPX™ lamp provides light for true tissue color and long-lasting performance. Coaxial optics produce a shadow-free spot, easier entry into undilated pupils, and a larger field of view versus standard ophthalmoscopes. Detects corneal abrasions with cobalt blue filter. Polarizing filter virtually eliminates corneal reflection. Sealed optics keep out dust and dirt. 18 unique aperture/filter combinations for greater versatility. Red-free filter may be used with any aperture28 focusing lenses with a range of -25 to +40 diopters.