 PreView PHP™
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Hyperacuity Diagram
Normal Retina vs. AMD with photoreceptor elevation
| | The PreView PHP is a diagnostic instrument to detect and monitor the progress of age-related macular degeneration (AMD).
The results have been clinically validated and the device has a standardized analysis process.
The main advantages of the PreView PHP are:
- Easy-to-use touch screen monitor
- Easy to use for patients
- No chin support needed
- Short examination time of approx. 5 minutes per eye
The main features of the PreView PHP are:
- Complete examination of the macula of 14°
- high sensitivity and specificity for detecting AMD visual abnormalities
- Automatic result analysis with visual field map, confidence level and reliability parameters
The technology:
The technology behind the PreView PHP is based on hyperacuity, a well-studied phenomenon. Hyperacuity is defined as the ability to recognize arc minute differences in the relative spatial localization of two or more visual stimuli (see illustration 1). The threshold value for hyperacuity can be as high as 6 arc seconds, which means normal resolution capacity (approx. 30-60 arc seconds in the fovea) is exceeded tenfold. Hyperacuity stimuli are highly resistant to retinal image disturbance and are therefore also suitable to determine the retinal function of patients with ocular media opacity.
When a liniar pattern is presented to a healthy retina, a co-linear series of retinal receptor fields are stimulated. Specialized neuronal networks in the visual cortex process this information and recognize a straight point deviation signal (see illustration, left draw). A geometric deviation of the photoreceptor localization occurs when the retinal pigment epithelium (RPE) detaches as a result of drusen (with intermediary AMD) and also, as is more frequently the case, in choroidal neovascularization. Therefore, different photoreceptors are stimulated with a detached RPE than with a normal retina. Linear signals are therefore perceived as distorted (see illustration, right draw). | | Clinical Papers
 Makula 2002
Makula 2003
ARVO 2002
Retinal Society Meeting, 2002
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