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NETRA: Interactive Display for Estimating Refractive Errors and Focal Range<br />Vitor Pamplona      Ankit Mohan      Manu...
2<br />NETRA: Near Eye Tool for Refractive Assessment<br />Vitor Pamplona      Ankit Mohan      Manuel M. Oliveira     Ram...
Challenge<br />2B have<br />refractive errors<br />0.6B have URE<br />4.5B have a <br />cell phone<br />6.5 Billion <br />...
4<br />Computational Photography<br />Optometry/Opthalmalogy<br />Measure .. Overcome Limitations .. Extend Abilities<br />
Accuracy<br />Sharpness Estimation is subjective<br />Brightness affects results<br />Pupil size variation and DoF<br />Co...
Needs expert,     Moving parts,     Shining lasers<br />* Phoropter-based: $5,000.00<br />
Shack-Hartmann Wavefront Sensor<br />Wavefrontaberrometer<br />Expensive; Bulky, Requires trained professionals<br />7<br />
Shack-Hartmann Wavefront Sensor<br />Laser<br />Sensor<br />8<br />Shack & Platt 1971<br />Liang et al 1994<br />David Wil...
Shack-Hartmann Wavefront Sensor<br />Laser<br />Spot Diagram<br />9<br />Sensor<br />Displacement = Local Slope of the Wav...
NETRA= Inverse of Shack-Hartmann<br />10<br />Spot Diagram on LCD<br />Cell Phone Display<br />Eye Piece<br />
11<br />Inverse of Shack-Hartmann<br />User interactively creates the Spot Diagram<br />Spot Diagram on LCD<br />Displace ...
Optometry<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Human Eye<br />Accommodation Range<br />Normal ...
Myopia (nearsightedness)<br />Infinity<br />Subject <br />cannot focus<br />at far distances<br />Accommodation Range<br /...
Myopia Correction<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Human Eye<br />Accommodation Range<br /...
Myopia Correction<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Divergent Lens<br />Human Eye<br />Acco...
Hyperopia (farsightedness)<br />Infinity<br />Wrong <br />focal point<br />Human Eye<br />Accommodation Range<br />Normal ...
Hyperopia (farsightedness)<br />‘Beyond’<br />Infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myo...
Hyperopia Correction<br />Infinity<br />Convergent Lens<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />My...
Refractive Errors and Shifted Range<br />Perfect vision<br />Need to measure<br />Myopia<br />Hyperopia<br />10cm<br />Inf...
Refractive Errors and Shifted Range<br />Perfect vision<br />Myopia<br />Hyperopia<br />10cm<br />Infinity<br />20<br />1m...
Relaxed Eye with Myopia<br />Eye<br />Red pointat infinity<br />Blurred <br />point<br />Focusing Range<br />perfect visio...
Relaxed Eye with Myopia<br />Eye<br />Pinholes<br />Distinct<br />image <br />points<br />Red pointat infinity<br />Focusi...
Relaxed Eye with Myopia<br />Eye<br />Display<br />A<br />Distinct<br />image <br />points<br />Virtual red pointat infini...
Relaxed Eye with Myopia<br />Eye<br />Display<br />Move spots towardseach other<br />A<br />Distinct<br />image <br />poin...
Relaxed Eye with Myopia<br />Eye<br />Display<br />Move spots towardseach other<br />A<br />Points <br />overlap<br />Virt...
Relaxed Eye with Myopia<br />Eye<br />Display<br />Move spots towardseach other<br />A<br />Points <br />overlap<br />Virt...
Relaxed Eye with Myopia<br />Eye<br />Points <br />overlap<br />Point at infinity<br />Focusing Range<br />perfect vision<...
Relaxed Perfect Eye <br />Display<br />A<br />Points <br />overlap<br />Virtual red pointat infinity<br />B<br />Focusing ...
Relaxed Eye with Hyperopia<br />29<br />Eye<br />Display<br />A<br />Distinct<br />image <br />points<br />Virtual red poi...
Relaxed Eye with Hyperopia<br />Move spots awayfrom each other<br />Display<br />Display<br />A<br />Points <br />overlap<...
Relaxed Eye with Hyperopia<br />Move spots awayfrom each other<br />Points <br />overlap<br />Virtual point“beyond” infini...
NETRA: Using pinholes<br />32<br />Pinhole array<br />Patterns on an LCD<br />
NETRA: Using Lens to Increase Light<br />Microlensarray<br />Patterns on an LCD<br />a<br />f<br />33<br />t<br />Pixel Pi...
Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia)<br />34<br />
Interactive Method<br />35<br />Farthest Focal Point<br />(myopia, hyperopia)<br />
Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia)<br />36<br />
Overview<br />37<br /><ul><li>Inverse of Shack Hartmann Wavefront Sensor
Hi-res displays  +  interaction
Measuring Spherical Error
No moving parts, lasers
Blur -> Alignment problem
~ Lightfield Display for Single Eye
Astigmatism
Novel Patterns
Focal Range
User Study</li></li></ul><li>Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/ast...
Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html<br />39<br />
Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html<br />40<br />
Refractive Power as a Function of Angle<br />41<br />Axis Cyl.<br />Cylinder<br />Unknowns:<br />Sphere<br />
Astigmatism<br />Cross or points may never meet with a 1d search !<br />42<br />
Astigmatism<br />Lines reduce the problem to a 1d search<br />43<br />
Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />44<br />
Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />45<br />
Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />46<br />
Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />47<br />
Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />48<br />
Evaluation Prototype<br />Camera simulates<br />the perfect eye<br />Trial lenses simulate lens aberration<br />Minificati...
Subjective Validation: User Study<br />50<br />
Measuring the Accommodation Range<br />51<br />Myopia<br />Perfect vision<br />Hyperopia<br />~10cm<br />Infinity<br />Ste...
Measuring the Accommodation Range<br />52<br />Myopia<br />Perfect vision<br />Hyperopia<br />~10cm<br />Infinity<br />Ste...
Measuring the Accommodation Range<br />53<br />Myopia<br />Perfect vision<br />Hyperopia<br />~10cm<br />Infinity<br />Ste...
Relaxed Eye <br />Display<br />A<br />Points <br />overlap<br />Virtual Point at the far limit<br />B<br />54<br />
Accommodated Eye <br />Display<br />Move points towards each other<br />A<br />Points <br />overlap<br />B<br />55<br />Vi...
Accommodated Eye <br />Display<br />Move points towards each other<br />A<br />Points <br />overlap<br />B<br />56<br />Vi...
Accommodated Eye <br />Display<br />Move points towards each other<br />A<br />Points <br />overlap<br />B<br />57<br />Vi...
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NETRA on SIGGRAPH 2010

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  • In this paper, we show a self-optometry solution. You look at a cell phone display thru a clip-on eye piece, interactively align a few patterns, hit calculate and get data for your eye prescription.
  • We call our tool NETRA: near eye tool for refractive assessmentsuch as nearsightedness/far/astigmatismBasic idea is to create a unique interactive lightfield display near the eye and is possible due to the highresolution of modern LCDs.
  • 2 billion people have refractive errorsAnd half a billion in developing countries worldwide have uncorrected vision that affects their daily livelyhood. They don’t have access to an optometrist or it simply too expensive. While making and distributing of lenses has become quite easy now, surprisingly there is still no easy solution for measuring eyesight.Can we use a fraction of the 4.5B cellphone displays to address this problem?
  • In Computational photography, we try to understand howcameras work, overcome their limitations and extend the abilities of these cameras. But we all carry atleast 3 cameras with us. Yes, your cellphone camera and the two eyes. Can we transition ideas from computational photography that deal with focus blur, motion blur and so on into optometry and opthalmalogy?
  • Reading charts appear to be an easy solution, this method has too many problems. Sharpness of legible text is very subjective. The brightness of the chart has to be very carefully chosen otherwise the pupil size will change, increasing depth of field, and allowing user to recognize even lower rows.The trial lenses + the lens frame the doctor will use also cost over $150% Reading chart tests involve using a frame or a phoropter. The doctor will swing a sequence of lenses in front of your eye and ask for which lens allows you to see the lower rows on the reading chart.
  • For better precision, there are many kinds of solutions, some really clever. The beauty of netra is that it avoids moving parts or shining lasers, and all intelligence is in the software.
  • The most accurate method is based on a so called SH WS. It involves shining a laser at the back of the retina and observing the wavefront using a sophisticated sensor.We ask user to generate a spot diagram. But navigating in a high dimensional space ischallenging so we come up with a strikingly simple approach to let the user interactively create the spotdiagram.We are first to make connection between Shack Hartmann and Lightfields (and it goes well with recentwork in computational photography about ALF and Zhang/Levoy). Connection to Adaptive optics/Astronomy. The way that this device works is that, it shines a lasers in the eye, the laser is reflected in the retina and comes out of the eye being distorted by the cornea. These light rays reaches an array of lenses that focus them to dots in a sensor. The device measures how much this dots deviate from the ideal case. Since it uses lasers, the device is expensive and requires trained professionals
  • For a normal eye, the light coming out of the eye forms a parallel wavefront. The sensor has a lenslet array and we get a spot diagram of uniform dots.This lenslet should remind you of a lightfield camera, and in fact Levoy and others showed last year that there is a close relationship between the two.In addition, Zhang and Levoy, plus our grp has shown the relationship between wavefront sensing and lightfield sensing.
  • When the eye has a distortion, the spot diagram is not uniform.And the displacement of the spots from the center indicates the local slope of the wavefront. From the slope one can integrate and recover the wave shape.
  • NETRA uses an exact inverse of this sensor. We get rid of the laser and we instead show the same spot diagram in a cellphone display. For normal eye, it will appear as a dot to the user.And then we replace the sensor for a light field display. If the user sees a single red dot, he does not need glasses, but if he sees more than one, he interacts with this display.
  • For eye with distortion, the user will interactively displace the 25 points so that he will see a single spot. Of course changing 25 spot locations is cumbersome, but we realize that there are only 3 parameters for eye-prescription and we help the user navigate thru this space efficiently.But if you think about these theory, you will realize that we have the dual of the shack-hartmann. First we though out the laser.
  • Before we go on. Here is a 2 minute primer on optometry.So, in a perfect vision system, the light coming from a point at infinity will converge to a single point at the retina. A subject with perfect vision see clearly from infinity to up to 10cm.
  • Myopes cannot see far. Therefore, all the rays coming from a point at infinity, converges before the retina. The Accommodation range for those people is shifted to close, so they can closer than regular individuals.
  • The correction for myopia includes a divergent lens, which brings the focal point back to the retina by shifting the Accommodation range.
  • Hyperopes cannot see close. All the rays coming from a point at infinity, converges behind the retina.
  • The Accommodation range for those people is shifted to the far field, so they can actually see ‘infinity and beyond’, much like the buzz lightyear.
  • The correction for myopia includes a convergent lens, which shifts the Accommodation range back to the regular indivudial.
  • We need to measure the difference between the subject’s farthest focal point wrt infinity.
  • And this is measured in diopters which is 1 divided by this distance.
  • So, lets start with an eye with myopia. Remember, they cannot see far, so a red point at infinity for them will look like a red blur.
  • Using Shceiner’s principle, if we put two pinholes in the field, this will instead create two distinct dots.
  • Instead of a distant point source, we put an LCD display behind the pinholes. If we draw two spots exactly under these pin-holes, we create a virtual point at infinity.
  • So, as we move the two red circles toward each other, the virtual point gets closer to the subject and he sees the two red dots getting closer.
  • When this two red circles overlaps for the subject, we can compute d based on the spot displacements
  • Which is the distance between the eye and this virtual point.
  • Turns out that the inverse of D is the refractive power required for this person to see clearly objects at infinity. In other words, the lens that will shift the accommodation range of this subject back to the regular one.
  • In case of a perfect eye using the system, since the subject can see far, he will see the two points overlapping in his retina, meaning that he does not need glasses.
  • Hyperopes focal point is behind the retina.
  • When they move these spots away from each other, we are moving the virtual point beyond infinityAnd buzz lightyear will entually see they overlap, and when this happens, we can compute the…
  • convergent lens required to shift their accommodation range to the normal stage.
  • The version that I showed to you uses pinholes to encode the apperture.
  • However, if we change these pinholes for lenses, we can increase the light and also the number of testing points in the corneal surface, meaning that we can actually create a map of one’s refractive error. As you can see the pixel pitch directly affects the precision of creating virtual depth as well as refraction estimation.
  • And number of clicks required for alignment indicates the refractive error
  • In practice we display lines on the screen and the subject overlaps these lines by pressing the buttons of the cell phone or in the computer.
  • Two main benefitsNo moving partsBlur into a more objective alignment problemUnfortunately, the lightfield and virtual point analogy does not extend to astigmatism and we can also compute ‘focal range’ rather than just relaxed state. Vitor will cover this.”ThanksRamesh, There is a third condition called astigmatism
  • which is anangle-dependent refractive error. An astigmatic subject has two main focal lengths in perpendicular meridians. One …
  • Stronger and one weaker
  • Think of a cornea with the shape of an american football creating a cylindrical aberration with unknown focal length and axis.
  • The required correction is now a function of measured angle. In order to measure the farthest point for these guys, we need to evaluate Cylindrical component, the Spherical component, and the angle theta on the equation. However, the interpolation of refractive powers between C and S leads to a situation where the pattern drawn on the screen matters.
  • As you can see in this video, the astigmatic lenses create a deviation on the path of the pattern, and they may never overlap, turning the alignment task into a 2D search for some angles.
  • However, if we drawn lines perpendicular to the measured angle, the alignment task is again an 1D search. The deviation still exists, but the pattern makes the task easier.
  • So, we do the alignment task for a few meridians
  • By showing oriented lines on the display.
  • In the end, we best fit the sinusoidal curve over the four measured values to estimate the astigmatic parameters.
  • In the end, we best fit the sinusoidal curve over the four measured values to estimate the astigmatic parameters.
  • Using a minification system, we performed user study with a high resolution display. Using a a camera to simulate perfect eye and a trial set of lenses to simulate lens aberration, the average spherical error was under 0.09 diopter and astigmatism axis error of 8 degrees.
  • In subjective human studies, the difference from known prescription was under 0.5 diopters. But note that the current prescription may not match the actual refractive error.
  • Ours is the only system where one can estimate not only the farthest point
  • one can focus but also
  • the nearest point without any mechanically moving parts. So, in order to measure the closest reading point
  • We draw a pattern on the screen that induces accommodation. In this way, when we move A and B closer on the screen,
  • the user will try to focus on a closer object. We can move this virtual point all the way to the nearest discernable point.
  • When the user is not able to focus anymore, the visual system give up and the user start seeing more than one pattern.
  • As I sad before, this is possible because we can draw whatever we want in the display. We tested many patterns, static and dynamic, including visual cryptography.
  • Turns out that the best pattern to induce accommodation is the sinosoidal curves aligned perpendicular to the measurement angle.
  • We have complete freedom for pattern G on display and the filter pattern h, which has been pin hole grid so far. But observe that subjects view is just a convolution of the pattern g and the filter h. So here is a very interesting effect. If we show this convoluted pattern with same filter, we get double convolution. If h is a broadband random dot pattern, the double convolution is a delta function, which means user will again see the pattern g.
  • We exploited this trick to build a viewmaster system. In this case, instead of moving lines closer we scale the pattern. The amount of scale give us the refractive power needed.
  • As a summary, our method has two steps. First measures the farthest point in focus in many angles using lines and the second step measures the nearest point using sinusoidals oriented on the angle of astigmatism.
  • Since we are relying on the user interaction, the subject has to be aware of the alignment tasks. So, very young Children may not be able to run the test. Instead of just one eye, one may use both eyes to exploit convergence. And of course, the resolution of NETRA itself is a function of the resolution of the display. With a 326 dpi display, resolution is 0.14 diopters and presciption glasses come in increments of 0.25 diopters. So our system is already sufficiently accurate.
  • For future work, we are partnering with many institutions that would like to use our device as an optometry tool and as a new tool for doing research. For instance, we think we have a new opportunity to monitor people eyesight over time.Field trials in regions with cultural and language barriers
  • Our work also create a new solution for a multi-focus displays without mechanically moving parts or large depths. Maybe we can even create alrm clock with optical correction built in. So you can read the clock without fiddling for eyeglasses.
  • Before I conclude, We would like to thank our collaborators and sponsors.(count to 5)
  • As a summary, we introduce the inverse of the Shack Hartmann system using a light field display and user interaction. We convert the blur problem into more objective alignment problem to estimate focal parameters. Our idea can be thought as thermometer for the eye. It is not a replacement for optometrist NETRA provides measurement, not prescriptions. At under $2, we have the cheapest accurateeye test ever. Given the 4.5 billion portable phones out there, we think it is an ideal solution in developing countries.
  • So, thanks everyone.
  • In this paper, we introduce the dual of the Shack Hartmann system using a light field display and user interaction. We also introduce an interactive technique to create objects at desired depths and an interface to measure refractive parameters of the eye. We validated this two main contributions by measuring lenses and comparing with lens prescriptions.
  • Not just user interaction , but far greater impact on people’s lives!
  • Image and Range
  • Include Myopia Range
  • Include Myopia Range
  • Show without accommodation and accomodate
  • Show without accommodation and accomodate
  • Show without accommodation and accomodate
  • ??
  • ??
  • Image and Range
  • Include Myopia Range
  • Include Myopia Range
  • Show without accommodation and accomodate
  • Show without accommodation and accomodate
  • Show without accommodation and accomodate
  • Show without accommodation and accomodate
  • … Which is anangle-dependent refractive erros. An astigmatic subject has two focal lengths in perpendicular meridians. One …
  • Stronger and one weaker
  • In this case, the red meridian is called Spherical, the Blue one is called cylindrical and the axis of the Red meridian indicates the angle of astigmatism. In order to measure the farthest point for these guys, we
  • In practice we display lines on the screen and the subject overlaps these lines by pressing the buttons of the cell phone or in the computer.
  • When the lines were overlapped, we compute the correction for myopia or hyperopia. However, there is a third disease called astigmatism.
  • The average error was under 0.5 diopters for both axis of astigmatism and the axis had an average error of 6 degrees.
  • For this case, the average error was 0.09 diopters for myopia and hyperopia and 0.23 for astigmatism. The axis of astigmatism had an error of 8.43 degress
  • We validate this extension by measuring the closest sharp point in cameras, and comparing with physical measurements.
  • The second round of validation included 6 humans. Both cases we could get pretty close to the actual closest sharp point.
  • In order to evaluate this technique, an LCD display was putted 2 meters away of a minification system, which created images in 3320 DPI. Inside the minification system we had a lens array. A camera was used to simulate the perfect eye.
  • There is a third condition called astigmatism which means an additional cylindrical aberration with unknown focal length and axis. The required correction now is dependent on angle and this leads to a situation where the pattern drawn on the screen matters.
  • There is a third condition called astigmatism which means an additional cylindrical aberration with unknown focal length and axis. The required correction now is dependent on angle and this leads to a situation where the pattern drawn on the screen matters.
  • There is a third condition called astigmatism which means an additional cylindrical aberration with unknown focal length and axis. The required correction now is dependent on angle and this leads to a situation where the pattern drawn on the screen matters.
  • Transcript of "NETRA on SIGGRAPH 2010"

    1. 1. NETRA: Interactive Display for Estimating Refractive Errors and Focal Range<br />Vitor Pamplona Ankit Mohan Manuel M. Oliveira RameshRaskar<br />1<br />
    2. 2. 2<br />NETRA: Near Eye Tool for Refractive Assessment<br />Vitor Pamplona Ankit Mohan Manuel M. Oliveira RameshRaskar<br />
    3. 3. Challenge<br />2B have<br />refractive errors<br />0.6B have URE<br />4.5B have a <br />cell phone<br />6.5 Billion <br />people<br />NETRA at LVP Eye Institute<br />3<br />
    4. 4. 4<br />Computational Photography<br />Optometry/Opthalmalogy<br />Measure .. Overcome Limitations .. Extend Abilities<br />
    5. 5. Accuracy<br />Sharpness Estimation is subjective<br />Brightness affects results<br />Pupil size variation and DoF<br />Cost<br />Trial Lens Set > $150<br />Bulky<br />Snellen chart<br />Phoropter<br />Trial lenses<br />Reading Charts<br />
    6. 6. Needs expert, Moving parts, Shining lasers<br />* Phoropter-based: $5,000.00<br />
    7. 7. Shack-Hartmann Wavefront Sensor<br />Wavefrontaberrometer<br />Expensive; Bulky, Requires trained professionals<br />7<br />
    8. 8. Shack-Hartmann Wavefront Sensor<br />Laser<br />Sensor<br />8<br />Shack & Platt 1971<br />Liang et al 1994<br />David Williams et al, Rochester<br />Spot Diagram<br />Planar Wavefront<br />Microlens Array<br />Shack-Hartmann ~ Lightfields<br />Levoy et al 2009 <br />Zhang and Levoy 2009: Observable Light Field<br />Oh, Raskar, Barbastathis 2009: Augmented Light Field <br />
    9. 9. Shack-Hartmann Wavefront Sensor<br />Laser<br />Spot Diagram<br />9<br />Sensor<br />Displacement = Local Slope of the Wavefront<br />
    10. 10. NETRA= Inverse of Shack-Hartmann<br />10<br />Spot Diagram on LCD<br />Cell Phone Display<br />Eye Piece<br />
    11. 11. 11<br />Inverse of Shack-Hartmann<br />User interactively creates the Spot Diagram<br />Spot Diagram on LCD<br />Displace 25 points but 3 parameters<br />
    12. 12. Optometry<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />10cm<br />Infinity<br />12<br />
    13. 13. Myopia (nearsightedness)<br />Infinity<br />Subject <br />cannot focus<br />at far distances<br />Accommodation Range<br />Normal Vision<br />Shifted Accommodation Range<br />Myopia<br />10cm<br />Infinity<br />13<br />
    14. 14. Myopia Correction<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Shifted Accommodation Range<br />Myopia<br />10cm<br />Infinity<br />14<br />
    15. 15. Myopia Correction<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Divergent Lens<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Corrected Myopia<br />Myopia<br />10cm<br />Infinity<br />15<br />
    16. 16. Hyperopia (farsightedness)<br />Infinity<br />Wrong <br />focal point<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />10cm<br />Infinity<br />16<br />
    17. 17. Hyperopia (farsightedness)<br />‘Beyond’<br />Infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />10cm<br />Infinity<br />17<br />
    18. 18. Hyperopia Correction<br />Infinity<br />Convergent Lens<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />10cm<br />Infinity<br />18<br />Corrected Hyperopia<br />
    19. 19. Refractive Errors and Shifted Range<br />Perfect vision<br />Need to measure<br />Myopia<br />Hyperopia<br />10cm<br />Infinity<br />19<br />1m<br />33cm<br />Distance<br />
    20. 20. Refractive Errors and Shifted Range<br />Perfect vision<br />Myopia<br />Hyperopia<br />10cm<br />Infinity<br />20<br />1m<br />33cm<br />Distance<br />10D<br />0D<br />3D<br />1D<br />-1D<br />-3D<br />Diopter<br />Diopter = 1/Distance<br />
    21. 21. Relaxed Eye with Myopia<br />Eye<br />Red pointat infinity<br />Blurred <br />point<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />21<br />
    22. 22. Relaxed Eye with Myopia<br />Eye<br />Pinholes<br />Distinct<br />image <br />points<br />Red pointat infinity<br />Focusing Range<br />perfect vision<br />Scheiner’s Principle<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />22<br />
    23. 23. Relaxed Eye with Myopia<br />Eye<br />Display<br />A<br />Distinct<br />image <br />points<br />Virtual red pointat infinity<br />B<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />23<br />
    24. 24. Relaxed Eye with Myopia<br />Eye<br />Display<br />Move spots towardseach other<br />A<br />Distinct<br />image <br />points<br />Virtual red pointat finite distance<br />B<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />24<br />
    25. 25. Relaxed Eye with Myopia<br />Eye<br />Display<br />Move spots towardseach other<br />A<br />Points <br />overlap<br />Virtual red pointat finite distance<br />B<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />25<br />
    26. 26. Relaxed Eye with Myopia<br />Eye<br />Display<br />Move spots towardseach other<br />A<br />Points <br />overlap<br />Virtual red pointat finite distance<br />B<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />26<br />
    27. 27. Relaxed Eye with Myopia<br />Eye<br />Points <br />overlap<br />Point at infinity<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />27<br />
    28. 28. Relaxed Perfect Eye <br />Display<br />A<br />Points <br />overlap<br />Virtual red pointat infinity<br />B<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />28<br />
    29. 29. Relaxed Eye with Hyperopia<br />29<br />Eye<br />Display<br />A<br />Distinct<br />image <br />points<br />Virtual red pointat infinity<br />B<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />
    30. 30. Relaxed Eye with Hyperopia<br />Move spots awayfrom each other<br />Display<br />Display<br />A<br />Points <br />overlap<br />B<br />Virtual point“beyond” infinity<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />30<br />
    31. 31. Relaxed Eye with Hyperopia<br />Move spots awayfrom each other<br />Points <br />overlap<br />Virtual point“beyond” infinity<br />Focusing Range<br />perfect vision<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />31<br />
    32. 32. NETRA: Using pinholes<br />32<br />Pinhole array<br />Patterns on an LCD<br />
    33. 33. NETRA: Using Lens to Increase Light<br />Microlensarray<br />Patterns on an LCD<br />a<br />f<br />33<br />t<br />Pixel Pitch<br />Virtual Depth<br />
    34. 34. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia)<br />34<br />
    35. 35. Interactive Method<br />35<br />Farthest Focal Point<br />(myopia, hyperopia)<br />
    36. 36. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia)<br />36<br />
    37. 37. Overview<br />37<br /><ul><li>Inverse of Shack Hartmann Wavefront Sensor
    38. 38. Hi-res displays + interaction
    39. 39. Measuring Spherical Error
    40. 40. No moving parts, lasers
    41. 41. Blur -> Alignment problem
    42. 42. ~ Lightfield Display for Single Eye
    43. 43. Astigmatism
    44. 44. Novel Patterns
    45. 45. Focal Range
    46. 46. User Study</li></li></ul><li>Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html<br />38<br />
    47. 47. Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html<br />39<br />
    48. 48. Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html<br />40<br />
    49. 49. Refractive Power as a Function of Angle<br />41<br />Axis Cyl.<br />Cylinder<br />Unknowns:<br />Sphere<br />
    50. 50. Astigmatism<br />Cross or points may never meet with a 1d search !<br />42<br />
    51. 51. Astigmatism<br />Lines reduce the problem to a 1d search<br />43<br />
    52. 52. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />44<br />
    53. 53. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />45<br />
    54. 54. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />46<br />
    55. 55. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />47<br />
    56. 56. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />48<br />
    57. 57. Evaluation Prototype<br />Camera simulates<br />the perfect eye<br />Trial lenses simulate lens aberration<br />Minification<br />LCD Display<br />49<br />
    58. 58. Subjective Validation: User Study<br />50<br />
    59. 59. Measuring the Accommodation Range<br />51<br />Myopia<br />Perfect vision<br />Hyperopia<br />~10cm<br />Infinity<br />Step 2: Near limit<br />Step 1: Far limit<br />
    60. 60. Measuring the Accommodation Range<br />52<br />Myopia<br />Perfect vision<br />Hyperopia<br />~10cm<br />Infinity<br />Step 2: Near limit<br />Step 1: Far limit<br />
    61. 61. Measuring the Accommodation Range<br />53<br />Myopia<br />Perfect vision<br />Hyperopia<br />~10cm<br />Infinity<br />Step 2: Near limit<br />Step 1: Far limit<br />
    62. 62. Relaxed Eye <br />Display<br />A<br />Points <br />overlap<br />Virtual Point at the far limit<br />B<br />54<br />
    63. 63. Accommodated Eye <br />Display<br />Move points towards each other<br />A<br />Points <br />overlap<br />B<br />55<br />Virtual pointgetting closer<br />Subject Accommodates <br />to fix the “blur” <br />
    64. 64. Accommodated Eye <br />Display<br />Move points towards each other<br />A<br />Points <br />overlap<br />B<br />56<br />Virtual pointgetting closer<br />Subject Accommodates <br />to fix the “blur” <br />
    65. 65. Accommodated Eye <br />Display<br />Move points towards each other<br />A<br />Points <br />overlap<br />B<br />57<br />Virtual pointgetting closer<br />Subject cannot accommodate more than the previous point<br />
    66. 66. Patterns for Alignment Task<br />58<br />A<br />B<br />A<br />B<br />A<br />B<br />A<br />B<br />A<br />B<br />Displayed<br />Subject view<br />A<br />B<br />A<br />B<br />A<br />B<br />A<br />B<br />A<br />B<br />Displayed<br />Subject view<br />Visual <br />Cryptography<br />[NaorShamir94]<br />
    67. 67. Patterns for Alignment Task<br />59<br />A<br />B<br />A<br />B<br />A<br />B<br />A<br />B<br />A<br />B<br />Displayed<br />Subject view<br />A<br />B<br />A<br />B<br />A<br />B<br />A<br />B<br />A<br />B<br />Displayed<br />Subject view<br />Visual <br />Cryptography<br />[NaorShamir94]<br />
    68. 68. Subject View as Convolution<br />Display<br />Subject’ s View <br />Subject’ s View<br />
    69. 69. Subject View<br />Viewmaster prototype<br />61<br />+3D to -5D with accommodation<br />Scaled Patterns <br />G(0D)<br />G(+5D)<br />G(-5D)<br />h - Jittered Pinholes<br />
    70. 70. Summary of Interaction<br />Accommodation Range<br />Farthest Point<br />(myopia, hyperopia, astigmatism)<br />NearestPoint<br />(presbyopia)<br />62<br />
    71. 71. Limitations<br />Children<br />Ability to align lines<br />Single Eye test<br />Other eye for convergence-forced accommodation<br />Resolution is a function of the display DPI<br />Samsung Behold II – 160 DPI – 0.35D<br />Google Nexus One – 250 DPI – 0.2D<br />Apple iPhone 4G – 326 DPI – 0.14D<br />63<br />
    72. 72. Future Work<br />Clinical research for an optometry device<br />Side-by-side validation tests<br />Field trials <br />Tests for cataract, lazy eye, etc<br />Opportunity to monitor one’s eyesight<br />Diabetes/Glucose non-invasive meter<br />Unstable lens prescriptions<br />Distribution in Developing Countries<br />Software app for free<br />Eyepiece blueprint to NGOs for <$1<br />More at EyeNetra.com<br />64<br />
    73. 73. Future Work<br />Multi-focus display without moving parts<br />[Akeley04][Rolland00][Hua09] [Barsky04]<br />Personalized devices (clear without glasses) <br />Alarm Clock <br />Cell phones<br />eReaders<br />65<br />Inju<br />Fernando Meyer<br />
    74. 74. Acknowledgements<br />Volunteers<br />Dr. Joseph Ciolino (MGH Mass Eye and Ear Inst.)<br />Dr. Fuentanta Vera Diaz (Schepens Eye Research Inst.)<br />Dr. James Kobler (MGH Mass Eye and Ear Inst.)<br />Dr. ShrikantBhardwaj, (LV Prasad Eye Institute, India)<br />Sponsors<br />CNPq-Brazil<br />Alfred P. Sloan Research Fellowship<br />Google <br />Samsung <br />66<br />
    75. 75. NETRA: Display for Eye Refraction Tests<br />Inverse of Shack-Hartmann wavefrontaberrometer<br />High-resolution displays and user interaction<br />Focal Parameters<br />Myopia, Hyperopia, Astigmatism<br />Focal range<br />Thermometer for the eye<br />Measurement not prescription<br />Promote Self Awareness<br />Impact in Developing Countries<br />600 Million without corrective glasses<br />$1 cost, easy to deploy<br />67<br />
    76. 76. NETRA: Interactive Display for Estimating Refractive Errors and Focal Range<br />Vitor Pamplona Ankit Mohan Manuel M. Oliveira RameshRaskar<br />68<br />
    77. 77. Computing <br />A<br />B<br />69<br />
    78. 78. 70<br />Display<br />g<br />h<br />
    79. 79. Books<br />71<br />
    80. 80. Contributions<br />Dual of the Shack-Hartmann system<br />Interface sensitive to refractive parameters of the eye<br />Four designs for the optical probe<br />Interactive method to create objects at desired depths<br />Patterns study for optimal alignment and accommodation<br />Method to measure refractive errors for far and close fields<br />Validation <br />Physical lens measurements <br />User study compared with current prescriptions<br />72<br />
    81. 81. Final Interactive Method<br />Accommodation Range<br />Farthest Focal Point<br />(myopia, hyperopia, astigmatism)<br />NearestFocal Point<br />(presbyopia)<br />73<br />
    82. 82. Partnerships for the Optometric Device<br />Vicky<br />LVP<br />Side-by-side testing<br />Field testing<br />Deployment partner<br />74<br />
    83. 83. Patterns Study<br />Displayed<br />Subject view<br />2nd<br />3rd<br />1st<br />Displayed<br />Subject view<br />75<br />
    84. 84. Measuring Accommodation Range<br />Displayed<br />Subject view<br />Displayed<br />Subject view<br />76<br />
    85. 85. Spherical: -0.5 diopters<br /> Cylindrical: -1.0 diopters<br /> Astigmatism Axis: 10°<br /> Accommodation Range: -5.07 diopters<br /> Sharp Focus Range: from 18cm to 2m<br />Estimated Prescription<br />-1.0<br />-0.5<br />10°<br />-1.0<br />Standard Prescription<br />Extra Info.<br />77<br />
    86. 86. Focusing Rangeand Refractive Errors<br />eye<br />perfect vision<br />need to measure<br />~25mm<br />myopia<br />hyperopia<br />~10cm<br />infinity<br />cornea<br />(~40D)<br />crystalline lens<br />(10~20D)<br />78<br />
    87. 87. Focusing Rangeand Refractive Errors<br />eye<br />perfect vision<br />~25mm<br />myopia<br />hyperopia<br />presbyopia<br />~10cm<br />infinity<br />cornea<br />(~40D)<br />crystalline lens<br />(0~10D)<br />79<br />
    88. 88. Head Mounted Display Prototype<br />0.5um microlensarray with spacer<br />resolution: 0.35D<br />LCD display<br />1806 dpi<br />80<br />
    89. 89. Samsung prototype<br />lcd: 180dpi<br />pinhole:a=3mm <br />lenslet:f=20mm<br />resolution: 0.71D<br />cost: ~$2 (pinhole)<br />resolution: 0.71D<br />controls<br />pinhole or microlens array with spacer<br />display patterns <br />audio feedback<br />81<br />
    90. 90. Nexus One prototype<br />lcd: 250dpi<br />pinhole: a=3mm, <br />lenslet: f=20mm<br />resolution:0.4D<br />cost: ~$2 (pinhole)<br />resolution: 0.4D<br />pinhole or microlens array with spacer<br />display patterns <br />controls<br />audio feedback<br />82<br />
    91. 91. Human Eye<br />Human Eye<br />cornea<br />(~40D)<br />crystalline lens<br />(10~20D)<br />83<br />
    92. 92. Normal Vision<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />30cm<br />Infinity<br />84<br />
    93. 93. Myopia<br />High-curvature cornea<br />Increased refractive power<br />Relaxed crystallin<br />Infinity<br />Subject <br />cannot focus<br />at far distances<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />30cm<br />Infinity<br />85<br />
    94. 94. Myopia Correction<br />Relaxed Crystallin<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Divergent Lens<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Corrected Myopia<br />Myopia<br />30cm<br />Infinity<br />86<br />
    95. 95. Hyperopia<br />Planar cornea<br />Decreased refractive power<br />Infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />30cm<br />Infinity<br />87<br />
    96. 96. Hyperopia<br />Planar cornea<br />Decreased refractive power<br />Subject accommodates to compensate for flat cornea<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />30cm<br />Infinity<br />88<br />
    97. 97. Hyperopia Correction<br />Now, subject <br />can focus<br />at infinity<br />without<br />accommodation<br />Infinity<br />Convergent Lens<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />Corrected Hyperopia<br />30cm<br />Infinity<br />89<br />
    98. 98. vs<br />Snellen chart<br />NETRA<br />smaller, less bulky, easier to carry<br />little no training required<br />allows self-evaluation<br />cheaper (if phone already exists)<br />trial lenses<br />phoropter<br />90<br />
    99. 99. Health Screening Tools<br />Blood Oxygenation<br />Blood Pressure<br />Visual Accommodation<br />Body Temperature<br />Blood Glucose<br />91<br />
    100. 100. Photography in 1960s<br />Photo: IllanaTamir<br />Photo: Roboppy<br />Expensive and bulky equipment<br />Requires specialized training<br />Very slow process<br />Mostly manual process<br />Go to a place to take the picture<br />Photo: Azigog<br />92<br />
    101. 101. Today, cameras are everywhere<br />Photo: Tyler<br />Photo: Derek K. Miller<br />Photo: John Kannenberg<br />But the photographer is still there!<br />93<br />
    102. 102. Optometry Today<br />Corneal Topographer<br />Wavefront Aberrometer<br />Phoropter<br />Expensive and bulky equipment<br />Require specialized training<br />Very slow process<br />Mostly manual process<br />Go to a place to get your eyes tested<br />94<br />
    103. 103. NETRA: Interactive Display for Measuring Refractive Error and Focal Range<br />95<br />
    104. 104. Astigmatism: radially asymmetric error<br />Cross or points may never meet with a 1d search<br />96<br />
    105. 105. Astigmatism<br />Lines reduce the problem to a 1d search<br />97<br />
    106. 106. Measuring Accommodation Range<br />98<br />
    107. 107. Normal Vision<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />30cm<br />Infinity<br />99<br />
    108. 108. Normal Vision<br />30cm<br />Infinity<br />Normal Vision<br />Accomodation:<br />Increase optical power<br />30cm<br />Subject <br />can focus<br />close<br />Human Eye<br />Accommodation Range<br />100<br />
    109. 109. Myopia<br />High-curvature cornea<br />Increased refractive power<br />Relaxed crystallin<br />Infinity<br />Subject <br />cannot focus<br />at far distances<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />30cm<br />Infinity<br />101<br />
    110. 110. Myopia<br />High-curvature cornea<br />Increased refractive power<br />Little or no accomodation<br />Subject <br />can focus<br />close<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />30cm<br />Infinity<br />102<br />
    111. 111. Myopia Correction<br />Relaxed Crystallin<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Divergent Lens<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Corrected Myopia<br />Myopia<br />30cm<br />Infinity<br />103<br />
    112. 112. Hyperopia<br />Planar cornea<br />Decreased refractive power<br />Subject accommodates to compensate for flat cornea<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />30cm<br />Infinity<br />104<br />
    113. 113. Hyperopia<br />Planar cornea<br />Decreased refractive power<br />Insuficient accommodation<br />for near vision<br />Subject <br />cannot focus<br />close<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />30cm<br />Infinity<br />105<br />
    114. 114. Hyperopia Correction<br />Now, subject <br />can focus<br />at infinity<br />without<br />accommodation<br />Infinity<br />Convergent Lens<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />Corrected Hyperopia<br />30cm<br />Infinity<br />106<br />
    115. 115. Computational Photography<br />Every one of us carries 3 cameras: <br />All of them have aberrations<br />107<br />
    116. 116. Camera Closest Focal Point<br />108<br />
    117. 117. Human Closest Focal Point<br />109<br />
    118. 118. Spherical Lens Measurement<br />Average error in 6 measurements for each green dot<br />Prototype Resolution: 0.16 diopters<br />110<br />
    119. 119. Spherical: -0.5 diopters<br />Cylindrical: -1.0 diopters<br /> Astigmatism Axis: 90°<br />Estimated Prescription<br />111<br />
    120. 120. Spherocylindrical Lens Measurement<br />Average absolute errors:<br /><ul><li>Spherical: 0.09 +/- 0.056 diopters
    121. 121. Cylindrical: 0.23 +/- 0.19 diopters
    122. 122. Axis: 8.43 +/- 6.16 degrees</li></ul>Spherical<br />Cylindrical<br />Prototype Resolution: 0.16 diopters<br />112<br />
    123. 123. Prescription User Study<br />Average absolute errors:<br /><ul><li> Spherical and Cylindrical: 0.5 +/- 0.2 diopters
    124. 124. Axis: 6 degrees</li></ul>113<br />
    125. 125. Hyperopia (farsightedness)<br />Subject accommodates to compensate for flat cornea<br />Infinity<br />Subject <br />can focus<br />at infinity<br />Planar cornea<br />Decreased refractive power<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />10cm<br />Infinity<br />114<br />
    126. 126. Hyperopia Correction<br />Now, subject <br />can focus<br />at infinity<br />without<br />accommodation<br />Infinity<br />Convergent Lens<br />Human Eye<br />Accommodation Range<br />Normal Vision<br />Myopia<br />Hyperopia<br />Corrected Hyperopia<br />10cm<br />Infinity<br />115<br />
    127. 127. Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html<br />116<br />
    128. 128. Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html<br />117<br />
    129. 129. Astigmatism: angle-dependent refractive error<br />http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html<br />118<br />
    130. 130. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia)<br />119<br />
    131. 131. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia)<br />120<br />
    132. 132. Interactive Method<br />Farthest Focal Point<br />(myopia, hyperopia)<br />121<br />
    133. 133. Measured data against prescriptions<br />13 volunteers<br />Average error:<br />Spherical and Cylindrical: 0.5 +/- 0.2 diopters<br />Axis: 6 degrees<br />Without eye drops to relax accommodation<br />We do not have control over the prescription<br />122<br />
    134. 134. Measuring lens power with an SLR camera<br />108 measurements for spherical Lenses:<br />Maximum average error of 0.09 diopters<br />8 measurements for spherocylindrical Lenses. <br />Avg. Spherical Error: 0.09 +/- 0.056 diopters<br />Avg. Cylindrical Error: 0.23 +/- 0.19 diopters<br />Avg. Axis Error: 8.43 +/- 6.16 degrees<br />123<br />
    135. 135. Validation 1: Cameras<br />Measuring closest focal point for cameras<br />124<br />
    136. 136. Validation 2: People<br />Measuring closest sharp point for 6 volunteers<br />125<br />
    137. 137. Evaluation Prototype<br />Camera simulates<br />the perfect eye<br />Pinhole or micro lens array with spacer<br />Minificationrelay optics <br />3,320 DPI<br />LCD Display<br />126<br />
    138. 138. Astigmatism<br />127<br />Axis Cyl.<br />Cylinder<br />Sphere<br />
    139. 139. Astigmatism<br />128<br />Axis Cyl.<br />Cylinder<br />Sphere<br />
    140. 140. Astigmatism<br />129<br />Axis Cyl.<br />Cylinder<br />Sphere<br />
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