We have developed a system for several automatic diagnose in Slit Lamp in order to provide 04 additional measurements to the biomicroscope: (1) counting of the endothelial cells of donated corneas; (2) automatic keratometry; (3) corneal ulcer evaluation; (4) measurement of linear distances and areas of the ocular image. The system consists in a Slit Lamp, a beam-splitter, some optical components, a CCD detector, a frame grabber and a PC. The optical components attached to the beam-splitter are the same for all the functions, except for 1. For function 1, we have developed an optical system that magnifies the image 290X and a software that counts the cells interactively and automatically. Results are in good agreement with commercial specular microscopes (correlation coefficient is 0,98081). The automatic keratometry function is able to measure cylinders over 30 di and also irregular astigmatisms. The system consists of projecting a light ring at the patient's cornea and the further analysis of the deformation of the ring provides the radius of curvature as well as the axis of the astigmatism. The nominal precision is 0,005 mm for the curvature radius and 2 degree(s) for the axis component. The results are in good agreement with commercial systems (correlation coefficient of 0,99347). For function 3, the ulcer is isolated by the usual clinical ways and the image of the green area is automatically detected by the developed software in order to evaluate the evolution of the disease. Function 4 simply allows the clinician do any linear or area measurement of the ocular image. The system is a low cost multi evaluation equipment and it is being used in a public hospital in Brazil.
Oftenly the evaluation of a cornea is made using a Slit Lamp where the aspect of the cells is qualitatively observed, there are elaborated apparels and consequently much more expensive that accomplish a quantitative analysis of the endothelium cells. To overcome the limitations of subjective analysis, manipulation difficulties and high cost, we developed a system coupled to the Slit Lamp (that magnifies 290X the cells) exhibiting the image in a computer monitor and a software dedicated for identification and counting the endothelium cells to at a low cost standardizing the diagnosis for the donated corneas.
A magnifying optical system (250-400X) attached to a Slit Lamp has been developed in order to evaluate the endothelium of donated corneas. The images from the endothelium are captured by a CCD and displayed in a PC monitor. The cost of the system is relatively low compared to the specular microscopes that are on the market for donated corneas (66% less expensive). The system offers two kinds of computer evaluation: interactive and automatic. The interactive counting of the endothelial cells provides a window of any shape and size desired by the clinician, where the cells are clicked by the mouse and the developed software estimates the number of endothelial cells in the cornea as a whole. The automatic counting of the cells is done by an image processing, where the cells are recognized by the developed software, without any interference of the clinician, and counted automatically. The most important features of this system compared to most that are on the market are: there are two ways for the clinical to count the cells and both can be used simultaneously (the automatic provides a quick counting of the cells and the interactive provides a wanted clinical interference on the result); many parts of the cornea can be evaluated and an average counting is provided (usually just the central part of the cornea is analyzed); real time image is provided instead of just a static image, which allows the clinician to have more information about the cornea such as the evaluation of the cells in the snail tracks.
One of the optical ways to evaluate the donated cornea in order to provide a diagnostic regarding its indication for transplant is to count the number of the living endothelial cells (over 2000 cells/mm2), which are responsible for maintaining the corneal transparency. Specular Microscopes are equipments which are exclusively dedicated for this kind of evaluation. However they are of high cost and most of the Eye Banks are not provided by them. Hence, the usual evaluation is done in a Slit Lamp (SL) -- 40X magnification -- and just the aspect of the cells are subjectively observed. In order to overcome the limitations of subjective assessment and high cost, we have developed a system attached to the SL (optical system with 250X magnification image captured by a CCD detector which displays the image of the cells on a PC monitor and a dedicated software) which is able to count the endothelial cells providing a lower cost objective diagnostic of the donated cornea.