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OPTICAL PRINCIPLES FOR ESTIMATION OF ENDOTHELIAL CELL DENSITY WITH THE NON‐CONTACT SPECULAR MICROSCOPE
Author(s) -
OLSEN THOMAS
Publication year - 1979
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.1979.tb01853.x
Subject(s) - contact angle , specular reflection , cornea , microscope , optics , curvature , microscopy , optical microscope , materials science , corneal endothelium , physics , mathematics , geometry , scanning electron microscope , composite material
In non‐contact specular microscopy of corneal endothelium, endothelial cell density is overestimated due to the angle of observation and the curvature of cornea. On the basis of theoretical considerations, it is concluded that if the angle of observation is kept at a small value the curvature of cornea contributes only insignificantly to this overestimation, the major determinant being the angle of observation. When an angle of 46° is chosen between slit illumination and optical axis of the microscope it is calculated that estimates of endothelial cell should be multiplied with a factor of 0.959 to correct for the angle effect. Six eyes were photographed with both a contact and non‐contact specular microscope and endothelial cell density estimated. Mean observed difference in cell counts was +5.5% without correction and +1.2% with correction for angle effect. 95% confidence limits for the difference with correction were ‐3.7 and +6.0% respectively showing that estimates of endothelial cell density obtained with the non‐contact specular microscope agree closely with those obtained by contact specular microscopy when corrected for angle of observation.