In the name of god

1. In the name of god

2. Evaluation of quality of visionHamid Fesharaki M D Best corrected visual acuity for far &near uncorrected visual acuity for far &near Current prescription, obtained vision Sharpest vision with the least amount of minus Duochrom test Cycloplegic refraction (1% tropicamide, waiting 30-60 minutes ) Vertex distance for eyes with ≥5 D of R E, pupil size, age Snellen chart Retinoscope Wavefront analysis Contrast sensitivity function Corneal topography

3. The basic of refractionSnell,s law

6. The power of a curved refracting surface is based on paraxial rays, according the First order optics for Ignoring the image quality P = n2-n1 ÷ r

7. Total lens power = P1+P2

8. Exact ray tracing in an spherical refractive surface:Theimage is not stigmatic

9. LME is based on approximation considering paraxisl rays onlyU + P = V :vergence rule

11. Deviations from stigmatic imaging are called aberrations Bluurre circle (point spread)

14. Normal eye and most of optical systems are not free from aberration (using aperture) The Cartesian ellipsoid produces a stigmatic image of only one object point

15. The basic of refractionFermat principle Natural processes occur in the most economical way, The light choose a path with least required time In a perfect optical system or a first-order optical system, all wavefronts are plane or spherical. Optical path length (OPL): light travel distance × refractive index Wavefronts are surfaces of constant OPL (Optical Path Length) from the source point. Rays indicate the direction of energy propagation and are normal to the wavefront surfaces.

17. Stigmatic image Fermat principle: all runners of the race should reach the finish line at the same time O.P.L (optical path length) to be equal for all rays Wave front is a photo of these runners when the fastest runner reaches the finish line At the reference sphere all runners are in the same phase, and it's radius is the distance between the sphere and the image The difference between the wave front and the reference sphere is the wave front aberration

18. Reference sphere:a circular arc centered on the image point with a radius equal to the image distance

19. Wave front aberration: the difference between the reference sphere and the wave front

21. Aberrations & irregular astigmatism Deviations from stigmatic imaging are called aberrations (monochromatic, chromatic) Monochromatic : Myopic & Hyperopic spherical errors, regular astigmatism Higher order aberrastions (irregular astigmatism): are detected by wave front aberrometry (sperical aberration, coma, trifoil)

22. Optical aberrations Approximately 80% - 90% of visual aberration error can be explained through the first and second order aberrations: 1st Order Aberation=Tilt (prism)2nd Order Aberation = Defocus (sphere) and cylinder The less frequent high order aberrations represent the residual 10% to 20% cases: (surgically induced) 3rd Order Aberation= Coma and trefoil4th Order Aberation = Spherical and quadrefoil5th Order Aberation = Distortions / irregular astigmatism6th to 8th Order Aberation = Significantly increasing levels of irregular astigmatism Chromatic aberrations

23. ConclusionThis project was incredibly interesting, as it allowed me to explore the various methods of diagnosing eye problems and obtaining corrective prescriptions with the tools and knowledge that we learned from the class. I have always been conflicted about LASIK surgery - wanting it because of the promise of significantly better vision, but nonetheless reticent about the actually procedure and the "permanence" of it all. Therefore, in researching this product I confirmed that the Ophthonix lenses represents a perfect solution for me and others who have wanted significantly better vision without the anxiety surrounding the LASIK corrective surgical procedure.

24. Common wave front aberrations Myopia (positive defocus) Hyperopia (negative defocus) Regular astigmatism (cylindrical aberration) Spherical aberration Coma 18 basic types of astigmatisms have been found by optical engineers (five of clinical interest)

27. Clinical importance of aberrations • Aberrations cause non stigmatic imaging(point spread function) damaging the image quality • Higher order aberrations are defined as any refractive error that cannot be corrected by spherocylindrical lense combinations • Despite the fact that we can measure many orders of aberrations, the human eye can only distinguish aberrations up to the fourth or fifth order

28. Clinical signs and symptoms of higher order aberrations Loss of spectacle best corrected visual acuity Poor cylinder axis determination Inconsistency between refraction and uncorrected vision Usually get corrected by hard contact lens Can not be detected by autorefractometer can be present in spite of good snellen acuity

29. Clinical signs andsymptoms of higher order aberrations Are usually accompanied by decreased contrast sensitivity Are mostly induced surgically The symptoms get worse at night (much governed by pupil size) Are mostly accompanied by topographic irregularities

30. What causes higher order aberrations? • Refractive surgery may increase the higher order aberrationshowever, not always enough to be perceptible to the patient. • Spherical aberration (associated with night vision problems) is often blamed on excessive flattening of the cornea as a • result of laser eye surgery or on too small a treatment zone relative to the patient's pupil size • . Coma (associated with double vision) is often caused by an off centre laser treatment (decentration)

32. Effect of high amount of induced aberrations on vision

35. How to represent wave front aberrations . By Zernike polynomials which are simply the mathematical formulas used to describe surfaces . 3-dimentional shapes (using graphing software) . 2-dimentional contour plots .Mentioning the amount of each basic form of astigmatism. .Thefuture prescriptions may consist of 8 or so numbers

36. Zernike Prescription,This case was best corrected using a spherocylindrical prescription of +0.19 –0.67 x 110 Zernike polynomials allow specification of sphere, astigmatism and higher-order aberrations for any wave front prescription shown below includes twelve Zernike modes. pupil diameter = 5.6 mmtotal RMS = 0.76 µm higher-order RMS = 0.51 µm

39. This chart reveals more common shapes of aberrations created when a wavefront of light passes through eyes with imperfect vision. A theoretically perfect eye (top) is represented by an aberration-free flat plane known, for reference, as piston. (Photo courtesy of Alcon Inc)

40. For many years, glasses and contact lenses have been used to correct large errors in the optical quality of the eye, namely defocus and astigmatism. However, it has been well known that the human eye also suffers from other subtle optical imperfections, which we refer to as higher order aberrations, in addition to typical defocus and astigmatic errors. Based on the technique devised by Liang et al. (1994), we measure the eye's wave aberration using aShack-Hartmann wavefront sensorto obtain a picture of the overall optical quality of the eye. The wave aberration may be mathematically represented and broken down into its constituent aberrations (such as defocus, astigmatism, coma, spherical aberration, etc.) using a Zernike decomposition. We are able to measure up to and including the 10th order Zernike modes, or a total of 63 individual aberrations.

41. Measurement of optical aberrationsWave front analyzer systems .Hartman-shack aberrometry (outgoing aberronetry), a low intensity laser beam is directed onto the retina, a lens array the light rays onto a photoreceptor (CCD) .Tscherning aberrometry (ingoing aberrometry), a collimated beam is passed through a mask of holes, a high magnification camera captures the image onto the retina .Retina ray tracing technique (ingoing aberrometry), a laser beam is used to scan across the pupil in a sequential manner, each position focus a single point on fovea .Optical path difference (OPD scan): combination of topography and retinoscopy

42. With aberration-free optics,wavefronts exiting the eye are perfectly flat (top). Refractive errors, such as myopia, distort the wavefront (bottom).Other refractive errors, including higher-order aberrations, cause wavefront distortions that differ in shape from those seen in simple myopia.

43. Hartman-shackaberrometer

44. Lenses placed at each aperture within the Hartmann screen