The Keratometer KMS-6 is a manual, portable ophthalmic instrument (also called an ophthalmometer) used by optometrists and ophthalmologists to measure the curvature of the eye's front surface (cornea), essential for detecting astigmatism, fitting contact lenses, and planning refractive surgery. Key features include a coincidence focusing system for precision, LED light, adjustable chin/head rests for patient comfort, and the ability to measure both main meridians (major and minor) from a single position, making it efficient for diagnosing corneal shape and power.