Exams {eye exam} can test for cataracts, glaucoma, and macular degeneration.
Axis
Axis is degrees at which to put cylindrical lens to give patient best vision. Axis is from 1 to 180 degrees.
Sphere
At Axis degrees, Sphere is diopters that give patient best vision. Plano or Pl {Plano} equals 0 diopters.
Cylinder
For Axis degrees plus or minus 90 degrees in the perpendicular direction, Cylinder is diopters that give patient best vision.
diopters
Sphere and Cylinder state lens strength in positive or negative diopters. Positive lenses enlarge, and negative lenses diminish. Lens strength is sum of Sphere diopters and Cylinder diopters. Higher positive is stronger. High-minus means lens is thicker at edge. High-plus means lens is thicker in middle.
Lens diopters add to eye diopters to result in total diopters. Nearsighted eyes have negative diopters, and glasses have positive diopters. Farsighted eyes have positive diopters, and glasses have negative diopters.
Prism and Base
Prism and Base can correct eye-muscle-problem altered eye orientations, but eye exams typically do not need to measure them.
Oval faces have rounded foreheads and chins, and chins and foreheads are similar in size {face shapes}. Rounded faces have circular foreheads and chins, and chins and foreheads are similar in size, with full cheeks. Square faces have wide foreheads, cheeks, and jaws, with angular jaws. Triangle faces have wider foreheads with small and rounded chins.
frames
Oval faces need geometric or round frames. Rounded faces need rectangular, navigator, square, or geometric frames. Square faces need round or oval frames. Triangle faces need square, navigator, rectangular, or geometric frames.
Dilating pupil {pupil dilation, eye}| {dilation, eye} allows looking at retinal periphery.
Prescriptions give lens shape for right eye {oculus dexter} (O.D.). For bifocals, prescription states distance vision (D.V.) and near vision (N.V.).
Prescriptions give lens shape for left eye {oculus sinister} (O.S.).
Because diopters add, the same prescriptions can have two forms. Cylinder can be always positive {plus-cylinder form}.
Because diopters add, the same prescriptions can have two forms. Cylinder can be always negative {minus-cylinder form}. For minus-cylinder form, Sphere is higher, and Axis is 90 degrees less or more than plus-cylinder form.
Lenses {glasses} can be single vision for near or far focus, bifocal, or trifocal.
material
Lenses can be glass, plastic, high-index, or polycarbonate. Glass is heavy and does not absorb UV light. Plastic is light but does not absorb UV light. High-index combines plastic and polycarbonate and absorbs UV light. Polycarbonate absorbs UV light.
polarization
Lens polarization can reduce glare.
coating
Scratch-resistant coatings are harder than plastic. Anti-reflective coatings reduce reflections. UV protection coats glass or plastic to absorb UV light. High-index and polycarbonate do not need UV coating, because they absorb ultraviolet light.
shape
Lenses have flat surfaces outside and curved surfaces towards eye, in meniscus shape.
shape: Spheric
Spheric means inner and outer surfaces are spherical, and outer surface has more curvature. Aspheric means spherical lenses have non-spherical edges, to maintain clear vision through lens edges.
shape: Atoric
Atoric means inner and outer surfaces change from spherical, and outer surfaces have less curvature.
frames
Oval frames have oval lenses. Geometric frames have oval tops and circular bottoms. Round frames have circular lenses. Square frames have square lenses. Rectangular frames have rectangular lenses. Navigator frames have trapezoid lenses slanted along nose. Aviator frames have trapezoid lenses with curved lower edges. Frames can be plastic or metal, including titanium. Colors are silver, gold, brown, black, and red.
Lenses {bifocal lens}| can have higher magnification for reading in bottom half and regular magnification for driving in top half.
Glasses {trifocal lens} can have reading in bottom third, computer in middle third, and driving in top third, or be progressive trifocals with no lines between thirds.
People can use lenses {contact lens}| that adhere to cornea. Contact lenses are safer in contact sports and are good lenses for magnifying and for correcting astigmatism. They can clean at night. People can replace soft lenses yearly, quarterly, monthly, or weekly. They fit closer to eye and so move less and fall out less. Soft lenses can be daily-wear or extended-wear. Rigid gas-permeable lenses are harder and allow sharper vision.
4-Medicine-Medical Examination
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Date Modified: 2022.0225