OpenOptix ABO Study Guide - Laramy-K Optical

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Hyperopia Hyperopia, also known as far-sightedness, occurs if the eye is too short or the curve of the cornea is too flat, causing light rays to focus behind the retina. Patients with hyperopia are able to see objects at distance, but near objects appear blurred. Mildly hyperopic patients may be able to see clearly at near without correction by using accommodation to compensate. Clear vision can be restored to most hyperopes through the use of plus-powered lenses. Astigmatism An even more common type of refractive error is astigmatism. Astigmatism occurs when the cornea has an oblong, football-like shape in one or more directions (or axes) causing light rays to focus on more than one point on the retina. Astigmatism is compensated for using cylinder powered lenses along the appropriate axis. Presbyopia As eyes age, the crystalline lens begins to lose elasticity. With the loss of elasticity, the eye loses the ability to accommodate or focus at near. This typically becomes noticeable around 40 years of age. This condition where the crystalline lens is unable to add sufficient power to focus at near is known as presbyopia. The loss of elasticity in the crystalline lens continues until somewhere around the age of 65 when all the elasticity is gone from the lens as is all ability to accommodate. Presbyopia can be compensated for through the use of plus-powered lens segments, reading glasses, or magnifying devices. This document is licensed under the Creative Commons Attribution 3.0 License. 7/30/2009 10
Anisometropia is a condition in which the two eyes have unequal refractive power. Antimetropia is an extreme case of anisometropia where one eye is myopic and the other is hyperopic. The unequal refractive states can often lead to diplopia (double vision) or asthenopia (eye strain). Anisometropia can adversely affect the development of binocular vision in infants and children, if there is a large difference between the two eyes. The brain will often suppress the vision of the blurrier eye in a condition called amblyopia, or lazy eye (a condition often mistakenly confused with phorias and tropias discussed later in this section). Extraocular Muscles The stabilization of eye movement is accomplished by six extraocular muscles attached to the eye via the sclera. The six muscles and their function are: Lateral rectus - moves the eye outward, away from the nose Medial rectus - moves the eye inward, toward the nose Superior rectus - moves the eye upward and slightly outward Inferior rectus - moves the eye downward and slightly inward Superior oblique - moves the eye outward and downward Inferior oblique - moves the eye outward and upward This document is licensed under the Creative Commons Attribution 3.0 License. 7/30/2009 11
Page 1 and 2: OpenOptix ABO Study Guide Ver. 1.3
Page 3 and 4: DOCUMENT SPONSORS AND CONTRIBUTING
Page 5 and 6: Scratch, UV, and Mirror Coatings...
Page 7 and 8: epithelium and Bowman’s Membrane
Page 9: Myopia Myopia, also known as near-s
Page 13 and 14: Chapter 2: BASIC OPTICAL PRINCIPLES
Page 15 and 16: The straw seems to be broken, due t
Page 17 and 18: images seen by both eyes, so the ey
Page 19 and 20: Chapter 3: LENS FORM Sphere It can
Page 21 and 22: The corrective power of a lens is d
Page 23 and 24: Most prescriptions have some combin
Page 25 and 26: A lens measure has three points of
Page 27 and 28: Curve Eccentricity Circle e = 0 Ell
Page 29 and 30: Transposing Prescriptions Transpose
Page 31 and 32: Reflectance The reflectance of the
Page 33 and 34: Pros Thinner and lighter than glass
Page 35 and 36: Principles of AR Coatings As light
Page 37 and 38: lenses are finally available for sa
Page 39 and 40: ack surface of the lenses. While po
Page 41 and 42: n = index of the main lens n s = in
Page 43 and 44: To find the optical center of the s
Page 45 and 46: wider and less distorted making it
Page 47 and 48: seen as signatures which continue t
Page 49 and 50: Occupational Lenses In the broadest
Page 51 and 52: Basic impact lenses must: • Have
Page 53 and 54: Calculate a Slab Off Example: OD -5
Page 55 and 56: The first multi-focal lens type we
Page 57 and 58: Effective Diameter (ED) - Twice the
Page 59 and 60: Nose pads: Nose pads are the small
Page 61 and 62:
Hinge: The hinge is the point where
Page 63 and 64:
Advantages of stainless steel frame
Page 65 and 66:
Plastics really have one general ca
Page 67 and 68:
We are often asked if the frames on
Page 69 and 70:
The last temple type was once calle
Page 71 and 72:
NO! This plastic frame makes very l
Page 73 and 74:
YES! In this figure the pads are ma
Page 75 and 76:
Secondary Frame Fitting Considerati
Page 77 and 78:
Frame Misalignment X-ing Skewed out
Page 79 and 80:
Temple Fit Ideally, the temples sho
Page 81 and 82:
Vertical angle - The angle of the p
Page 83 and 84:
Adjusting the endpieces is preferab
Page 85 and 86:
Part Identification 1. Eyepiece 7.
Page 87 and 88:
6. Eyeglass Table - The eyeglass ta
Page 89 and 90:
which should be documented along wi
Page 91 and 92:
Common Handtools for Frame Adjustme
Page 93 and 94:
Other Tools and Instruments Pupilom
Page 95 and 96:
(R2004) ANSI Z80.25 - 1996 (R2002)
Page 97 and 98:
Cylinder Power For Progressives Cyl
Page 99:
DOCUMENT LICENSE This work is licen
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