Op cs Review Mark E. Wilkinson, OD Khadija S. Shahid, OD, MPH line drawings by Angie England Department of Ophthalmology and Visual Sciences OPTICS REVIEW Mark E. Wilkinson, OD Khadija S. Shahid, OD, MPH The University of Iowa Carver College of Medicine Department of Ophthalmology and Visual Sciences OPTICS REVIEW By Mark E. Wilkinson, OD and Khadija S. Shahid, OD, MPH Line Drawings by Angie England Wilkinson & Shahid Optics Review OPTICS REVIEW Table of Contents 1. Light ...................................................................................................... 1 a. Nature of Light .............................................................................1 b. History of Light ............................................................................2 c. Movement of Light........................................................................2 2. Vergence................................................................................................ 3 3. Lens Systems......................................................................................... 5 4. Simple Lens Formula ........................................................................... 7 5. Depth of Focus .................................................................................... 12 6. Depth of Field ..................................................................................... 12 7. Multiple Lens Systems ....................................................................... 12 8. Lens Effectivity................................................................................... 16 9. Focal Points......................................................................................... 18 10. Ray Tracing – Lenses....................................................................... 19 11. Optical Media and Indices of Refraction ....................................... 22 12. Snell’s Law of Refraction ................................................................ 24 13. Apparent Thickness Formula ......................................................... 26 14. Law of Reflection and Critical Angle ............................................. 28 15. Mirrors .............................................................................................. 30 16. Ray Tracings – Mirrors ................................................................... 33 17. Prisms ................................................................................................ 38 18. Prentice’s Rule ................................................................................. 39 19. Lenses ................................................................................................ 41 a. Surface type ................................................................................41 b. Cylinder Optics ..........................................................................41 c. Astigmatism Types ......................................................................42 d. Astigmatism of Oblique Incidence .............................................42 e. The Interval or Conoid of Sturm ................................................42 f. Spherical Equivalent ...................................................................43 g. Power Transposition: converting plus to minus cylinder and vice versa ............................................................................43 h. Base Curves of Lenses ...............................................................43 20. Aberrations ....................................................................................... 45 a. Chromatic (color) Aberrations ..................................................45 b. Chromatic dispersion .................................................................45 i Wilkinson & Shahid Optics Review c. Monochromatic Aberration ........................................................45 i. Spherical aberration .............................................................45 ii. Aperture size: .......................................................................46 iii. Coma ...................................................................................46 iv. Aplanatic system .................................................................46 v. Curvature of field .................................................................46 vi. Distortion ............................................................................47 21. Schematic Eye................................................................................... 48 22. Refractive/Axial Myopia and Hyperopia ....................................... 49 23. Knapp’s Law .................................................................................... 50 24. Far Point of the Eye ......................................................................... 50 25. Accommodation................................................................................ 51 a. The Amplitude of Accommodation, ............................................51 b. The Range of Accommodation ...................................................51 c. Resting Level of Accommodation: ..............................................51 d. Measuring Accommodation: ......................................................52 i. Near point of accommodation “Push Up Test”....................52 ii. Prince Rule ..........................................................................52 iii. Spherical Lens Test .............................................................52 26. Near Point of the Eye ....................................................................... 55 27. Magnification.................................................................................... 57 a. Relative Distance Magnification................................................57 b. Relative Size Magnification .......................................................57 c. Angular Magnification ...............................................................58 d. Magnification Basics .................................................................58 e. Transverse/Linear Magnification...............................................59 f. Axial Magnification = M1 X M2 ..................................................61 g. Effective Magnification = Me = dF............................................63 h. Rated Magnification = Mr = F/4 ...............................................63 i. Conventional Magnification = Mc = dF + 1 ..............................64 j. Magnification Ratings.................................................................64 k. Determining Needed Magnification ...........................................64 28. Telescopes ......................................................................................... 65 a. Keplerian telescopes ..................................................................65 b. Galilean telescopes ....................................................................65 29. Aniseikonia ....................................................................................... 74 a. Cylindrical Corrections .............................................................76 ii Wilkinson & Shahid Optics Review 30. Multifocal Design ............................................................................. 78 31. Visual Acuity Assessment ................................................................ 82 32. Contrast Sensitivity .......................................................................... 86 33. Jackson Cross Cylinder (JCC) ....................................................... 87 34. Duochrome Test ............................................................................... 87 35. Night Myopia .................................................................................... 88 36. Ring Scotoma .................................................................................... 88 37. Lensmaker equation ........................................................................ 88 38. IOL Power (SRK Formula)............................................................. 88 39. Instruments ....................................................................................... 89 a. Lens Clock = Lens Gauge = Geneva Lens Measure .................89 b. Manual lensometer.....................................................................91 c. Direct ophthalmoscope ..............................................................91 d. Indirect Ophthalmoscopy ...........................................................92 e. Keratometer................................................................................92 f. Gonioscope .................................................................................93 g. Retinoscope/Retinoscopy ............. Error! Bookmark not defined. History of Retinoscopy ............ Error! Bookmark not defined. Retinoscopy.............................. Error! Bookmark not defined. h: Optical Doubling .......................................................................93 i. Handheld Lenses for Slit Lamp Microscopy ...............................94 j. A-Scan .........................................................................................94 k. Bagolini Lenses ..........................................................................94 l. Duochrome (Red-Green) Test ....... Error! Bookmark not defined. m. Worth 4-Dot ..............................................................................95 n. Stereo Fly Test ...........................................................................95