keratometer


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Related to keratometer: Pachymeter, Lensometer

keratometer

 [ker″ah-tom´ĕ-ter]
an instrument for measuring the curves of the cornea.

ker·a·tom·e·ter

(ker'ă-tom'ĕ-tĕr),
An instrument for measuring the curvature of the anterior corneal surface.
Synonym(s): ophthalmometer
[kerato- + G. metron, measure]

ker·a·tom·e·ter

(ker'ă-tom'ĕ-tĕr)
An instrument for measuring the curvature of the anterior corneal surface.
Synonym(s): ophthalmometer.
[kerato- + G. metron, measure]

keratometer

An optical instrument used to measure the radius of curvature of the cornea. See also KERATOMETRY.

keratometer

Optical instrument for measuring the radius of curvature of the cornea in any meridian. By measuring along the two principal meridians, corneal astigmatism can be deduced. The principle is based on the reflection by the anterior surface of a luminous pattern of mires in the centre of the cornea in an area of about 3.6 mm in diameter. Knowing the size of the pattern h and measuring that of the reflected image h′ and the distance d between the two, the radius of curvature r of the cornea can be determined using the approximate formula.
r = 2d (h′/h)
In addition, a doubling system (e.g. a bi-prism) is also integrated into the instrument in order to mitigate the effect of eye movements, as well as a microscope in order to magnify the small image reflected by the cornea. This instrument is used in the fitting of contact lenses and the monitoring of corneal changes occurring as a result of contact lens wear (Fig. K2). The range of the instrument can be extended approximately 9 D by placing a +1.25 D lens in front of the objective to measure steeper corneas. The range in the other direction can be extended by approximately 6 D using a −1.00 D lens to measure flatter corneas. Syn. ophthalmometer. See fitted on K; keratoscope; liquid lens; photokeratoscopy; Wollaston prism; Javal's rule; Topogometer; videokeratoscope.
Fig. K2 Schematic diagram of the Reichert keratometerenlarge picture
Fig. K2 Schematic diagram of the Reichert keratometer

Table K2 Extended keratometer range
with 21.00 Dwith 11.25 D
actual drum reading (D)extended value (D)actual drum reading (D)extended value (D)
36.0030.8745.0052.46
36.5031.3045.5053.05
37.0031.7346.0053.63
37.5032.1646.5054.21
38.0032.5947.0054.80
38.5033.0247.5055.38
39.0033.4548.0055.96
39.5033.8848.5056.55
40.0034.3049.0057.13
40.5034.7349.5057.71
41.0035.1650.0058.30
41.5035.5950.5058.88
51.0059.46
51.5060.04
52.0060.63

keratometer

an instrument for measuring the curves of the cornea.
References in periodicals archive ?
Canon offers and markets a full line of digital imaging solutions for the ophthalmic world, including Non-Mydriatic and Mydriatic Retinal cameras, full auto-tonometer and full auto-ref keratometers and image management software, all of which will be on display at the show.
Measured in the spectacle plane Ocular astigmatism Taken directly from the spectacle astigmatism, after adjusting for the BVD Corneal astigmatism Astigmatism arising just from the cornea, and can be measured using a keratometer Residual astigmatism Residual astigmatism = ocular astigmatism-- corneal astigmatism When a spherical RGP lens is placed on the cornea, it will correct the corneal astigmatism, but not lenticular astigmatism.
The keratometer readings, together with the refraction, will guide the practitioner to the nature of the astigmatism.
Tenders are invited for Autorefractometer With Keratometer 2 Nos.
Pre-lens non-invasive tear break-up time (NIBUT) was evaluated without application of fluorescein dye with different types of mires, such as placido disc of the videokeratograph or mires of the keratometer.
5kw), Autorefractometer with keratometer,Advanced corneal Topography,Digital lensometer,ECG machine with Print and View,ECG Jelly,MVA kit Deep freezer,Biosafety Cabinet,
Corneal topographers are ideal, but if a keratometer is used then the average of the flattest and steepest "K" readings are calculated, and the first trial lens is selected as having a base curve as close as possible to 0.
While, the diagnostic devices market has been further classified into fourteen major devices namely, autorefractometers, slit lamps, tonometers, ophthalmoscopes, fundus cameras, fluorescein angiography, optical coherence tomography (OCT) systems, Echography systems, Keratometers, Gonioscopes, Pachymeters, perimeters, corneal topographers and specular microscopes.
The diagnostic and monitoring device segment is further sub-segmented into fundus cameras, pachymeters, specular microscopes, optical coherence tomography scanners, keratometers, ophthalmic ultrasound imaging systems, wavefront aberrometers, tonometers, slit lamps and corneal topographers.
Currently, most eye care practitioners use keratometers to measure corneal curvature.
16, 2014 /PRNewswire/ -- This report analyzes the worldwide markets for Ophthalmic Instrumentation in Units and US$ Thousands by the following Product Segments: Diagnostic Devices (OCT Systems/Ophthalmoscopes, Optical Biometers, Slit Lamps, Tonometers, AutoRefractors & Keratometers, Perimeters, Fundus Cameras, Diagnostic Ultrasound Equipment, Others), and Surgical Products (Ophthalmic Lasers, & Ophthalmic Surgical Microscopes).
The diagnostic and monitoring devices include optical coherence tomography (OCT) scanners, ophthalmic ultrasound imaging systems, fundus cameras, ophthalmoscopes, retinoscopes, wavefront aberrometers, corneal topographers, autorefractors, pachymeters, keratometers, specular microscopes, biometers, perimeters, tonometers, slit lamps, and other devices.