ABO Exam Prep Part 2 Basic Optic Principles questions and answers

UV radiation Radiation type of wavelengths shorter than 400 nm UV C Division of UV radiation ranging from 290-200 nm & is extremely dangerous, absorbed by the ozone layer UV B Division of UV radiation ranging from 320-290 nm & causing sunburn, corneal burn, retinal damage, & eventually cataracts; mainly absorbed by the cornea & partly the crystalline lens UV A Division of UV radiation ranging 400-320 nm & causing suntan & cataracts; primarily absorbed by the crystalline lens 5, 1 The FDA requires that sun lenses transmit no more than __% of UV A & no more than __% of UV B Glare control lenses Lenses that go beyond UV wavelength for superior protection Infrared radiation Radiation type of wavelength 750-1400 nm Dispersion The breaking down of white light into seven component colors Green When white light enters the eye, this color focuses upon the retina Red When white light enters the eye, this color focuses beyond the retina Blue When white light enters the eye, this color focuses in front of the retina 39.37 in One meter is equivalent to this amount of inches 25.4 mm One inch is equivalent to this amount of mm 390-750 nm The range of visible light Wave theory Theory that describes light as moving in waves, like the motion of waves in water Corpuscular theory Isaac Newton's theory that describes light as being minute particles, called photons, which originate from the light's source Index of refraction The density of any given material Refraction The bending of light Reflection When a beam of light bounces back from a material; directly proportional to refractive index Absorption The amount of light that is trapped in an optical material when light passes through; directly proportional to refractive index Transmission The amount of light that passes through a material; inversely proportional to refractive index 290 nm Crown glass absorbs UV light below this wavelength 350 nm CR-39 absorbs UV light below this wavelength 1.523 Index of refraction of crown glass 1.498 Index of refraction of CR-39 1.586 Index of refraction of polycarbonate 1.600 Index of refraction of high index plastic 1.805 Index of refraction of flint glass n = speed of light in air / speed of light in material Formula for index of refraction 1.530 Standard index of refraction Base Light always bends toward the ___ of the prism Image displacement The appearance of an image to be in a position other than the position from which the light had originally emanated Prism diopter 1 cm / 1 m D = 1/f Lens power in terms of focal length (m) f = 1/D Focal length (m) in terms of lens power Prentice's Rule Prism diopters = F * dec (mm) / 10 Real image The type of image formed by a plus lens Virtual image The type of image formed by a minus lens Apex An image is always displaced toward this part of the prism Prism A wedge of optical material Induced prism Unwanted prism that occurs when the OC of a lens is not correctly placed in front of the patient's MRP