This compact unit plots thirteen different maps to provide information on the corneal shape, wavefront, internal aberrations and visual quality of the eye. The OPD-Scan provides a Refractive Biopsy of the eye and its major refractive components.
This diagnostic platform is employed for a variety of uses including patient screening, preoperative evaluation, and follow up care. The OPD-Scan can determine the source of visual blur, qualify and quantify the components of "irregular astigmatism".
Among other uses, the OPD-Scan can be used for determining the effect
of corneal and intraocular procedures, following the wavefront and refractive
progression of a cataract, CL fitting or the effect of pharmacological
constriction of the pupil. Additionally it can increase patient flow and
reduce chair time with the patient.
OPD-Scan
Measuring Principle - Over 8000 data points of Wavefront and Topography
aligned and registered and the same axis.
The NIDEK OPD-Scan simultaneously measures wavefront and topography using the principles of retinoscopy and placido disk. This ensures the maps are aligned and registered with respect to each other.
This facilitates the correlation of corneal contribution to the wavefront
aberrations of eye and the internal contribution to wavefront.
Wavefront
The OPD-Scan uses a unique measurement principle, based on retinoscopy,
called "spatial dynamic skiascopy" to determine the wavefront
aberrations of the eye. The fundamental differences between retinoscopy
and dynamic skiascopy include the use of infrared light instead of visible
light and the measurement of time lag for photodetector simulation instead
of lenses to determine the refractive power of 1440 data points within
the physiologically dilated pupil rather than just the refraction of the
visual axis. The raw data is plotted refractive power maps and also converted
to conventional wavefront maps and graphs.
The OPD-Scan uses placido disk technology, which is considered the gold standard of corneal topography to plot approximately 7000 data points over the entire corneal surface.
This technology is considered the gold standard of topography. Combining video imaging techniques and computer processing algorithms the OPD-Scan captures the image of reflected rings of light from the cornea and analyzes thousands of data points to plot the corneal contour, shape and refractive power.
