A quick internet search for handheld topographers yields no more than two legitimate results and puzzling enough to us; the boom in telemedicine and mobile exams of recent hasn’t seemed to have influenced many manufacturers into making less desktop things and more handheld things. Perhaps it’s because contact lens fitting is considered an ‘in-office’ procedure but we can’t see any real reasons why this cannot be done in the field just the same. And thus we digress– is handheld topography any good and any reliable? Perhaps, but it isn’t without its faults and quirks. Given that topography requires Placido Ring reflection off the cornea for a proper measurement, the angle of the operator matters, and lighting (especially with light iris’) matters a bit more. In an office setting, the environment is yours for the choosing, however in a nursing home with bright fluorescent lighting and windows in the lobby, handheld topography may prove a bit more difficult. That isn’t to say that the Keratron Scout doesn’t work, and even in difficult settings/patients the Scout topographer tries hard and analyzes data quite well. It is important to realize that although the Scout is a handheld device, it does require connection to its computer-based software to organize patients and analyze data thoroughly. The Scout topographer itself is merely the patient-capture mechanism– thus, a connected laptop is going to be required in your mobile operation. Despite this minor drawback, the Scout is relatively easy-to-use and loaded with connected curvature and axial mapping software, and RGP contact lens features built-in that compare nicely with the older Atlas topography systems from Zeiss systems. A audible beeping guides the operator smoothly into the proper position, and brightness/focus adjustments on the patient module make aligning the patient similar to that of a desktop instrument. Surprisingly, compliant patients are rather easy to acquire images from and the Scout’s charging cradle creates a base for the instrument in case the handheld option isn’t working out.
OUR TAKE: Handheld and portable despite computer-based software. Image capture is not as difficult as you’d imagine.
Keratron Scout, in its three configurations – portable, fixed, intraoperative – is a compact, transportable and practical device. It adds flexibility of use to the precision, high repeatability and the capacity to highlight the slightest details, characteristics that have made Keratron the topographer of reference in the sector.
The VK carries 28 mires, which are shaped as back-lighted concentric rings, alternatively 14 black and 14 whites, arranged into the internal conical surface of a cone, made of transparent perspex, called Mires Cone which is removable and which carries a opto-electronic couple, made of an IRED and a photo-transistor, set at two opposite sides of its external edge. The exclusive design of the “mires cone” with EPCS (Eye Position Control System) makes Keratron Scout fully adaptable to the most complex cases, ensuring the best efficiency and a lower number of repeated attempts.
The Cone is back illuminated by the Lamp Board which contains a tight array of LEDS. Behind the Lamp Board there are the fixation led, focused at a large distance, and the TV Camera.
The Keratron Scout is a Modular “Computer Assisted VideoKeratographer” (also said CAVK in the literature) that, just like the Keratron, is designed to measure the shape of the cornea and to represent it as symbolic colour map of the corresponding axial or refractive powers, of its local curvatures or of its elevations in several formats (corneal topography).
The local curvature maps reveal the slightest details that are hidden by axial maps, thus allowing a careful diagnosis even in presence of peripheral or small localized phenomena.
The height is represented with reference to a sphere that can be positioned by the operator. Height difference maps (for example post- minus-preoperative) can be obtained after matching at three reference points, so to cancel the relevant “tilt”.
to contrast sensitivity are invaluable tools for the assessment of the corneal refraction. The adoption of corneal aberration evaluation has broken new ground in the links with excimer lasers for custom ablation. The cornea is analysed to measure the corneal wavefront. The Zernike polynomials, which allow analysis of individual aberrations and the analysed pupil size and position, are user-selectable
The dual illumination of Placido rings by infrared and visible light allows measurement of the pupil size and center at different ambient light levels.
A sophisticated software module, made possible by the accurate height reproducibility of the Keratron, produces highly realistic simulations of the fluorescein patterns of any RGP contact lens, which can be fitted according to:- Choice of a production lens
– Use of a custom fitting protocol
– Automatic choice according to manufacturers direction
– Custom geometry contact lens design (e.g.: CALCO, Wave etc..)The geometries of major RGP contact lens manufacturers are available. However the user can easily create new virtual trial-sets.
By applying automatic lens selection protocols, some labs have reached a first-fit success rate up to 90%.Customizable auto-fit criteria and functions, based on curvature or simple clearance height targets, help you standardize your optimal fitting choices to design lenses.
Thus custom lenses can be designed with any geometry, including inverse geometries for ortho-K or post-refractive surgery.Linking corneal topographic data with custom design software allows the manufacture of “custom cornea contour” lenses that give a better vision, excellent wear tolerance and exceptional stability.In the future, the analysis of corneal aberrations can be incorporated in the design of ideal soft and RGP lenses to compensate for all optical aberrations. The result will be a highly customized lens that achieves maximum individual vision.
The EyeQuip program will run on any Pentium IV 1.6 GHz 256 Mb RAM computer/laptop, running Windows XP or Windows 7.
The Keratron Scout topographer charges via a charging cradle (included) receiving power from any 110V power outlet.
The Keratron is not intended for use without the included EyeQuip topography software installed locally on a computer.