scleral indentation

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indentation, scleral

A clinical procedure used in conjunction with indirect ophthalmoscopy in which some slight pressure is applied to the sclera to bring the peripheral retina into view. Retinal detachments and tears, for example, are more easily seen with this procedure. Pressure is usually applied with an instrument called an indentor. The technique is contraindicated in patients with elevated intraocular pressure. See indirect ophthalmoscope.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
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The subject panel has two switches labeled "discomfort" and "pain," and the experimenter panel has two switches labeled "pain" and "emergency stop." The subject panel is used for recording the subject's pressure perceptions related to discomfort and pain [29,31] and as a safety device: when the pain switch is pressed, the indentor is released automatically.
The new approach is to progressively load the indentor with comparatively small loads and to measure the indentor penetration depth with the indentor in place.
Determining Young's modulus from the indentor penetration diagram, Zavod Lab 39: 1137-1142.
He grasps the indentor across the palm of his other hand, with the tip emerging below the little finger.
The Rockwell test can be performed with various indentor sizes and loads.
In this regard, other researchers [11, 13-16] have reported that such behaviour of the hardness profile not only depends mainly on the hardness scattering of the joint welded at 63 mm/min might be related to the fact that during hardness measurement, the indentor is penetrated in a location without any precipitate and it is impressed on the alloy matrix, while in other places where the hardness is high, the indentor may have been located on the precipitates [9, 14-16].
This method is based on the penetration of a specific type of indentor pushed into the specimen by a specific dead weight; the test instrument is called a durometer (figure 2), hence the term durometer hardness.
These were then indented at a loading rate of 0.5 mm/min using a spherical steel indentor of diameter 5 mm driven by an Instron 1185 mechanical testing machine.
Microhardness by Vickers method was determined on transverse sections using an optic microscope Polyvar Met, equipped with an attachment for measurement of hardness at 5 g load to indentor and 10 s loading duration.
Conventional test methods utilized to quantify the scratch resistance were measurements such as: reduction in gloss of a coating after being subjected to a traversing tangential load of known particle size abrasive (crockmeter test); measurement of damage depth and recovery of damage depth of a coating after exposure to a single point indentor (nanoindentor (4,5)); or quantitative measurement of the fraction of elastic, viscoelastic creep, and fracture response of a coating after exposure to a single point indentor (scanning probe microscope (6)).
The recognized tests for hardness of materials, Brinell, Rockwell, Vickers, etc, consist of applying known weights and specific indentor shapes to the surface of material samples and measuring the resulting permanent indentations.