Specular Microscopy Study

Endotheliopathies

The corneal endothelium plays an important role in regulating stromal hydration and maintaining the transparency of the cornea. For evaluating the cornea, the most important parameters are corneal endothelial morphology and central corneal thickness. The specular microscope does this. The image in specular microscope is obtained by the specular reflex at a regular, smooth-surfaced interface of two refractive indices, with the angle of the light passing into the cornea equal to the angle of reflection to the observer. To obtain a clear image, the endothelial apical surface must be smooth and uniform and the cornea must be transparent. Nowadays different types of specular microscope exist. The investigators propose to compare the endothelial cells with two specular microscopes: the Konan SP4000, which is the current model and used for standard of care, to the Nidek CEM-350, which is a newly marketed device. The investigators would like to evaluate the patients in the clinic and have assessments completed with both specular microscopes. Nidek will be loaning the specular microscope, NIDEK CEM-530, for the study.

Subjects that provide informed consent will be clinically evaluated (visual acuity, refraction, slit-lamp biomicroscopy, tonometry) by a corneal specialist. After endothelium evaluation with use of slit-lamp biomicroscopy a grade of severity will be given. The grades will be based on the density and confluence of guttae and presence of clinical edema. Two microscopes, non-contact specular microscope (KONAN SP4000) and paracentral non-contact specular microscope (NIDEK CEM-350), will be used for the exam. For each patient both eyes will be examined by the two non-contact specular microscopes. Three pictures of the central cornea will be captured from the standard specular microscope. The paracentral specular microscope can capture image of one central point, eight paracentral points with 5° visual angle and six peripheral points with 27° visual angle. It will capture 16 images and automatically will classify based on quality and the ability to be analyzed. The optimal image for analysis will be indicated with orange highlight. Once the image is selected, a new manual or automatic software will be used to count the endothelial cells, complete analysis will be automatically performed.

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