| Features |
| |
| Videokeratoscope |
|
Standard Corneal Topographer
with placido ring. Infrared
placido ring illumination makes
patient comfortable during
examination. |
| |
| Wavefront sensor |
| Topcon Wave-Front Analyzer
uses a Hartmann-Shack sensor.
It analyzes higher order
aberrations in a central 4mm
(Photopic) and 6mm (Scotopic)
circle on the pupil. It will collect up to six
readings per eye.
The integrated database
function saves examination
time in a busy clinic.
|
| |
| PSF (Point Spread Function) |
| The PSF simulates the spot light projected on the retina when a
spot shape ray of light is entered into the eye.
The S.C.A. of the eye is already corrected by the Zernike
Polynomials calculation. The ideal situation is to have exact
spot on the retina as it enters, however even an ideal lens
system can not achieve it due to its diffraction etc.
Strehl ratio is a ratio between the central intensity of the
ideal lens and that of the measured eye. Therefore, the reading
closer to 1.00 means better optical quality.
By analyzing this image as well as the Strehl ratio, it is possible
to know if there is aberration that can not be corrected by
spectacles etc such as irregular astigmatism.
|
| |
| MTF (Modulation Transfer Function) |
|
The MTF indicates the relation between optical resolution and
contrast. On the graph below, the vertical direction indicates
the strength of contrast and the horizontal direction indicates
the resolution power.
As shown on the graph, when the resolution is higher (when
there are more lines per millimeter), the contrast (ability to
define black and white) becomes lower and vice versa.
|
| |
| Landolt Simulations |
|
By using the PSF data from the above, the "Landolt Simulation"
simulates how the Landolt rings will be projected on the
patient's retina after S.C.A. is corrected by spectacles etc.
Notes: Objects are projected as an inverted mirror image
on the human retina, therefore the simulated image is also
an inverted mirror image.
When a human observes an object, the eye constantly moves
around the object. Therefore, even the simulated Landolt Ring
image can not be recognized. The patient might be able to
recognize the Landolt Ring in real life after the correction.
|
| |
| Axial power maps |
|
Axial power map from the Topcon wavefront sensor is compatible with conventional videokeratoscopes. An instantaneasis map is also available.
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| |
| Specifications |
|
Refractive power measurement
Measuring range |
Hyperopia : 0 to +22D 0.25D step display (switchable to 0.12D display)
Myopia : 0 to -25D 0.25D step display (switchable to 0.12D step display)
Astigmatism : 0 to 8D(+ or -) 0.25D step display(switchable to 0.12D step display)
Axial angle : 0 to 180° 1° step display (switchable to 5° step display)
|
|
Corneal curvature measurement
Measuring range
|
Radius of corneal curvature : 5.00~10.00mm, 0.01mm step display
Corneal refractory power: 67.50~33.75D, 0.25D step display (switchable to 0.12D step display)
(corneal refractive index=1.3375)
Corneal astigmatic power : 0~10D(+ or -)
0.25D step display (switchable to 0.12D step display)
Corneal astigmatic axial angle : 0~180°(1° step display)
|
|
| Refractive aberration measurement |
Hartmann-Shack wave-front analyzer
High order aberration : Zernike polynominal up to 6th order or up to 4th order
Aberration display : Total aberration, High order aberration
Measuring range : 0±15D
Measuring area : 7.0mmø
|
|
Corneal mapping/
Corneal wave-front aberration measurement |
Number of Placido rings : 11
Number of measurement sampling points : 3,960
Radius of corneal curvature : 5.00~10.00mm
Corneal refractory power : 67.50~33.75D(corneal refractive index=1.3375)
Measuring area : ø0.8mm~ø9.2mm (radius of corneal curvature=8mm)
Color corneal mapping display
High order aberration : Zernike polynominal up to 6th order or up to 4th order.
Aberration display : Total aberration, High order aberration
|
|
| Minimum pupil diameter measurable(REF)
|
ø2.0mm |
|
| Target fixationL_atham_and_P_hillips |
Auto fog system |
|
| Measurement data display |
TV monitor screen |
|
| Measurement data recording |
Built-in printer (Data of 10 measurements of right and left eyes) |
|
| Collimation |
TV monitor screen |
|
| TV monitor |
5 in. |
|
| PD measurement |
85mm measuring range max., 1mm display unit |
|
| External output terminal |
RS232C, VIDEO-OUT (ANALOG, DIGITAL) |
|
| Power source/power consumption |
AC 100, 120, 220, 230 and 240V, 50/60Hz, 160VA |
|
| Operating temperature |
10-40°C |
|
| Main body travel |
back & forth : 40mm, sides : 86mm, up & down : 30mm |
|
| Chinrest travel |
60mm(up & down) |
|
| Dimensions |
310(W) x 475(D) x 500(H)mm |
|
| Weight |
23kg |
|