In a previous study we have shown that correction of peripheral refractive errors can improve the remaining vision of subjects with large central visual field loss. Measuring peripheral refractive errors with traditional methods is often difficult due to low visual acuity and large aberrations. Therefore a Hartmann–Shack sensor has been designed to measure peripheral wave front aberrations in subjects using eccentric viewing. The sensor incorporates an eye tracker and analyzing software designed to handle large wave front aberrations and elliptic pupils. To ensure that the measurement axis is aligned with the direction of the subject's preferred retinal location, a special fixation target has been developed. It consists of concentric rings surrounding the aperture of the sensor together with a central fixation mark along the measurement axis. Some initial measurements on subjects using eccentric viewing have been performed successfully. As a first step in improving the peripheral optics of the eye, the wave front has been used to calculate the eccentric refraction. This refraction has been compared to the refraction found with the PowerRefractor instrument. Measuring the off-axis wave front is a fast way to assess the optical errors in the subject's eccentric viewing angle and to better understand the problems of eccentric correction.
Introduction: In a previous study we have shown that correction of peripheral refractive errors can improve the remaining vision in the preferred retinal location (PRL) of subjects with large central visual field loss (CFL). Measuring peripheral refractive errors with traditional methods is often difficult due to the low visual acuity and large aberrations. Therefore a Hartmann-Shack (HS) sensor has been designed to measure peripheral wavefront aberrations in CFL subjects. Method: The HS sensor incorporates an eyetracker and analyzing software designed to handle large wavefront aberrations. To ensure that the measurement axis is aligned with the subject's PRL, a special fixation target has been developed. It consists of concentric rings surrounding the aperture of the HS together with a central fixation mark along the measurement axis. Results: Some initial measurements on subjects with CFL have been performed successfully. As a first step in improving the peripheral optics of the eye, the wavefront data have been used to calculate the subject's optimal eccentric refraction. Conclusion: Measuring the wavefront aberrations is a fast and easy way to assess the details of the optics in subjects with CFL. The wavefront data can then be used to better understand the problems of eccentric correction.
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