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Measurement of Corneal curvature   Principle of Keratometry Gauri S. Shrestha   M.Optom, FIACLE
Keratometers ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Keratometers: uses ,[object Object],[object Object],[object Object],[object Object]
History  ,[object Object],[object Object],[object Object],[object Object],[object Object]
Principle of Keratometry: Optical ,[object Object],[object Object],[object Object]
PRINCIPLES OF KERATOMETRY OPTICAL
PRINCIPLES OF KERATOMETRY OPTICAL ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Optical Principle of Keratometry ,[object Object],[object Object],[object Object],[object Object],[object Object]
DOUBLING PRINCIPLE ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
DOUBLING SYSTEMS ,[object Object],[object Object],[object Object],[object Object],[object Object]
DOUBLING SYSTEMS ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
DOUBLING SYSTEMS ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Objective Fixed graticule
Instrumentation ,[object Object],[object Object],[object Object],[object Object]
[object Object],[object Object]
Optical System of Keratometer
Types of Keratometers ,[object Object],[object Object],[object Object],[object Object]
Types of Keratometers ,[object Object],[object Object],[object Object],[object Object],[object Object]
Keratometers ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Keratometers Humphrey Keratometer B & L Keratometer
Topcon OM-4 Ophthalmometer
Javel’s keratometers : Varieties of Mires
[object Object],[object Object],Automated Keratometry
[object Object],[object Object],[object Object],[object Object],Automated keratometry
To expand the range of measurement   ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
To expand the range of measurement ,[object Object],[object Object],[object Object],[object Object],[object Object]
Expanded ranges of Keratometer
Keratometry Calibration ,[object Object],[object Object],[object Object]
Keratometry ,[object Object],[object Object],[object Object]
CALIBRATION FORMULA ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Measurement ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Measurement ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Measurement ,[object Object],[object Object],[object Object]
Procedure  ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Mires in keratometer Focusing keratometric target Locating the principle meridians Determining the corneal refractive power
PROBLEMS OF MEASUREMENT ,[object Object],[object Object],[object Object],[object Object]
SOURCES OF   ERROR ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
SOURCES OF ERROR   ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
PHOTOKERATOSCOPE/ PLACIDO DISK ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Placido Disc ,[object Object],[object Object]
Sun Nidek Photokeratoscope ,[object Object]
PHOTOKERATOSCOPE/ PLACIDO DISK ,[object Object],[object Object],[object Object],[object Object]
Images ,[object Object],[object Object],[object Object],[object Object]
Images
Disadvantages of the Placido Disc ,[object Object],[object Object],[object Object],[object Object],[object Object]

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Measurement of corneal curvature