slit lamp in optometry office (opthalmology office) used for eye examination to check eye health and vision

instrument opthalmology biomicroscope clinic eyeglass numbers ophthalmic diagnosis eye test device iris gadget optician health slit lamp eyesight sight lens curve examination microscope measurement optometrist sighted refractive error exam tool light diagnostic equipment vision prescription refractor measure opthalmic healthcare medicine opthalmologist sit glasses cornea optometry phoropter office used check