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A-scan ultrasound biometry. A-scan ultrasound biometry, commonly referred to as an A-scan (short for Amplitude scan), uses an ultrasound instrument for diagnostic testing. [1] A-scan biometry measures the axial length (AL) of the eye prior to cataract surgery in order to assess the refractive power of the intraocular lens that will be implanted.
The Alpins Method uses vector mathematics to determine a goal for astigmatism correction and analyze factors involved if treatment fails to reach that goal. The method can also be used to refine surgical techniques or correct laser settings in future procedures. [5]
Humphrey field analyser (HFA) is a tool for measuring the human visual field that is commonly used by optometrists, orthoptists and ophthalmologists, particularly for detecting monocular visual field. [1] The results of the analyser identify the type of vision defect. Therefore, it provides information regarding the location of any disease ...
Mild astigmatism has a higher prevalence than moderate and significant astigmatisms and increased until the age of 70, while moderate and significant astigmatisms showed an increase in prevalence after the age of 70. [33] Of the levels of astigmatism, mild astigmatism is most prevalent, making up about 82% of the total reported astigmatisms. [33]
Phacolytic glaucoma (PG) is a form of glaucoma which is caused due to a leaking mature or immature cataract.Inflammatory glaucoma which occurs in phacolysis is a condition which is a result of the leakage of protein within the lens into the capsule of a mature or hyper mature cataract and involves a simple procedure to be cured that is referred to as cataract extraction.
In this brief vision test specialized cameras detect each eye's light reflexes, which the equipment's software or a test administrator then interprets. If photoscreening indicates the presence of risk factors, an ophthalmologist can then diagnose the condition after a complete eye exam, including dilating the pupils and measuring the focusing ...
Astigmatism (optical systems) An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances. The term comes from the Greek α- (a ...
Keratometer. A keratometer, also known as an ophthalmometer, is a diagnostic instrument for measuring the curvature of the anterior surface of the cornea, particularly for assessing the extent and axis of astigmatism. It was invented by the German physiologist Hermann von Helmholtz in 1851, although an earlier model was developed in 1796 by ...