System and method for illumination and fixation with ophthalmic diagnostic instruments
An eye measurement system may include a target that moves transverse to an optical path from the target to eye, so as to relax accommodation of the lens of the eye. The target may move transverse to the optical path on a display. The patient may be fogged while the target moves transverse to the optical path, and the target may become smaller such that the patient perceives the target to be moving away from the patient. A pupil camera may measure eye position that can be correlated with the position of the target on the display to determine that the patient has maintained fixation on the moving target. A visible measurement light beam may be pulsed subsequent to and/or during motion of the target that relaxes accommodation of the eye so as to avoid visual interference of the measurement light beam with the target on the display.
1. An optical device to diagnose an eye of a patient, the device comprising:
a display with a target visible to a patient;
an optical system to project the target display along an optical path from the display to the patient;
a sensor to measure optical aberrations of the eye; and
a pulsed measurement light source coupled to the measurement sensor and visible to the patient, wherein the pulsed light source is pulsed while the target is moved transverse to the optical path so as to relax an accommodation of the eye of the patient, wherein the display further comprises a stationary scene presented while the target moves transverse to the optical path.
2. The diagnostic device of claim 1 , wherein the pulsed measurement light source is synchronized with the target.
3. The diagnostic device of claim 1 , wherein the optical system is adapted to fog the target to relax the accommodation of the eye.
4. The diagnostic device of claim 1 , wherein the pulsed light source is synchronized with the sensor.
5. The diagnostic device of claim 1 , wherein the pulsed light source is synchronized with a frame transfer rate to a processor.
6. The diagnostic device of claim 1 , wherein the light source comprises at least one of a laser, a super luminescent diode or a light emitting diode.
7. The diagnostic device of claim 1 , wherein the sensor comprises at least one of a Shack-Hartmann wavefront sensor, a Tscherning aberrometer, or a spatially resolved refractometer.
8. A method of diagnosing an eye of a patient with a sensor, the method comprising:
presenting a target on a display with the target visible to the patient;
pulsing a light source visible to the patient to measure aberrations of the eye while the target is moved transverse to the optical path so as to relax an accommodation of the eye of the patient; and
presenting a stationary scene to the patient while the target moves transverse to the optical path.
9. The method of claim 8 wherein the target moves transverse to an optical path from the target to the patient.
10. The method of claim 9 wherein the light source is pulsed in response to a common timing signal and wherein the target moves transverse to the optical path in response to the common timing signal.
11. An optical device to diagnose aberrations of an eye of a patient, the device comprising:
an aberration sensor to measure the optical aberrations of the eye;
a pulsed measurement light source synchronized with the measurement sensor, wherein the pulsed light source is pulsed for a short duration while a fixation target is moved transverse to an optical path so as to avoid visual interference with the fixation target; and
a stationary scene presented while the target moves transverse to the optical path.
12. The diagnostic device of claim 11 , wherein the pulsed measurement light source is adapted to pulse a few times with each pulse synchronized to a separate frame of the sensor.
13. The diagnostic device of claim 12 wherein a duration of each pulse of the measurement light source corresponds to no more than about 30% of a duration of the separate frame of the sensor.
14. The diagnostic device of claim 11 , wherein the short pulse comprises a short duration no more than about 100 ms and the long pulse threshold corresponds to a long duration of at least about 500 ms.
15. The diagnostic device of claim 11 , wherein the pulsed measurement light source comprises infrared light.
16. The method of claim 8 , further comprising determining a range of accommodation by presenting the target at different specific vergences over a range of vergences.
17. The method of claim 8 , further comprising decreasing the size of the target while the target moves transverse to the optical path.
18. The method of claim 8 , further comprising rotating the target about any axis relative to a visual axis of the patient while the target moves transverse to the optical path.