Perimetry

Contents • 1 Summary • 2 The field of vision and characteristics of visual field loss in glaucoma • 3 Devices and Algorithm • 3.1 1st generation FDT perimetry • 3.2 Second generation Humphrey Matrix FDT perimetry • 4 Testing methods • 5 Interpretation • 5.1 Reliability indices • 6 FDT vs SAP • 7 Uses in clinical practice • 8 References Summary Various testing modalities are currently available for detecting visual field loss. This page will focus specifically on the role of frequency doubling technology in assessing visual fields. Frequency doubling technology (FDT) perimetry is based on a flicker illusion created by counterphase flickering of a low spatial frequency sinusoidal grating at a high temporal frequency. The frequency doubling illusion (see example y cells in the magnocellular layer. The field of vision and characteristics of visual field loss in glaucoma The normal field of vision encompasses approximately 50 degrees nasal and superior, 70 degrees inferior, and 90 degrees temporal. Early glaucomatous nerve damage is thought to be due to loss of large-diameter retinal ganglion cells, namely the M y cells of the magnocellular layer. The earliest visual field defects in glaucoma have been described as the nasal step or paracentral scotoma, followed by extension of these defects centrally over time. Hart and Becker have described three phases of glaucomatous nerve damage. Devices and Algorithm The 2 commercial FDT perimeters available are the first generation Frequ...

Clinical perimetry measures the differential light sensitivity, which is a measure of the dimmest light stimulus seen by the patient against the illuminated background. Diagnostic information is enhanced by the program and strategy of the administered test that is built into the machine software. The visual function results need to be measured for reliability and reproducibility to be useful clinically for diagnostics and follow-up. • Fankhauser F, Koch P, Roulier A. On automation of perimetry. Graefes Arch Clin Exp Ophthalmol. 1972:126–50. • Flammer J, Jenni A, Bebie H. The OCTOPUS G1 program. Glaucoma. 1987;9:67–72. • Weber J, Klimaschka T. Test time and efficiency of the dynamic strategy in glaucoma perimetry. German J Ophthalmol. 1995;4:24–31. • González de la Rosa M, Rodríguez J, Rodríguez M. Flicker-TOP perimetry in Normals and Patients with ocular hypertension and early Glaucoma; Perimetry Update 1998/1999. p. 59–66. • Schiefer U. Realization of semi-automated kinetic perimetry (SKP) with the Interzeag 101 Instrument. In: International Perimetric Society (IPS) Meeting. 2002. • Bebie H, Flammer J, Bebie T. The cumulative defect curve: separation of local and diffuse components of visual field damage. Graefes Arch Clin Exp Ophthalmol. 1989;227:9–12. • Visual field Digest 6th Edition 2016, Haag-Streit AG, Koniz Switzerland (ISBN 978-3-033-06001-2). Cite this chapter Rangaraj, N.R., Sathyan, P. (2021). Interpretation of Octopus Visual Fields. In: Patyal, S., Gandhi, M. ...

What is visual field testing? As you focus on the words in this article, how much can you see out of the corners of your eyes? Can you tell what's happening in your surroundings? Your visual field is how wide of an area your eye can see when you focus on a central point. Visual field testing is one way your Visual field testing can detect blind spots A visual field test can determine if you have blind spots (called scotoma) in your vision and where they are. A scotoma’s size and shape can show how eye disease or a brain disorder is affecting your vision. For example, if you have Ophthalmologists also use visual field tests to assess how vision may be limited by Six types of visual field tests 1. Confrontation visual field test A common way for your doctor to screen for any problems in your visual field is with a confrontation visual field test. You will be asked to look directly at an object in front of you, (such as the doctor’s nose) while one of your eyes is covered. Your doctor may hold up different numbers of fingers in areas of your peripheral (side) vision field and ask how many you see as you look at the target in front of you. 2. Automated static perimetry test To check for a suspected eye problem or monitor the progress of an eye disease, your ophthalmologist will rely on more specific tests to measure how you see objects in your field of vision. The automated static perimetry test is used for this purpose. It helps create a more detailed map of where you can and...

Taking visual field test using a Goldmann perimeter A visual field test is an eye examination that can detect dysfunction in central and The exam may be performed by a technician in one of several ways. The test may be performed by a technician directly, with the assistance of a machine, or completely by an automated machine. Machine-based tests aid diagnostics by allowing a detailed printout of the patient's visual field. Other names for this test may include perimetry, Tangent screen exam, Automated perimetry exam or Goldmann visual field exam. [ citation needed] Examination methods [ ] Techniques used to perform this test include the confrontation visual field examination (Donders' test). The examiner will ask the patient to cover one eye and stare at the examiner. Ideally, when the patient covers their right eye, the examiner covers their left eye and vice versa. The examiner will then move his hand out of the patient's visual field and then bring it back in. Commonly the examiner will use a slowly wagging finger or a hat pin for this. The patient signals the examiner when his hand comes back into view. This is frequently done by an examiner as a simple and preliminary test. Perimetry [ ] Perimetry or [ failed verification] It is the systematic measurement of differential light sensitivity in the perimeter of the visual field. Automated perimeters are used widely, and applications include: diagnosing disease, job selection, visual competence assessment, school or commu...

Table of Contents • • • Peripheral, or indirect, vision allows you to see things to the side of you (things in your periphery) without turning your head. A visual field test can help to diagnose potential problems within your field of vision, and it includes testing your peripheral vision. There are some DIY at-home visual field exams you can do to determine if your peripheral vision is in good shape. If you are concerned about your peripheral vision, or you are at risk for peripheral vision loss, talk to your eye doctor and have your field of vision tested professionally. Peripheral Vision Explained Your field of vision includes both what you can see clearly right in front of you and what you can see less clearly off to the sides. Your central vision, made up of the fovea, only makes up a Peripheral vision is less direct than central vision. It helps you to see things to the side of you and objects that are not directly in your central vision line of sight. Peripheral vision accounts for around 100 degrees of your 170-degree field of vision. It allows you to see scenes and objects around you without the need to turn your head to take them in. • See better in the dark and low-light conditions. • Observe things out of the “corner of your eye.” • Detect motion. • Keep you from running into things. • Sort through traffic and crowds with improved visual perception. • Read and understand material faster by helping you to scan text outside of your focus to better comprehend it. ...

This chapter provides an overview of these structures, details methods of visual field testing, and describes a framework for the localization and diagnosis of disorders affecting the afferent visual pathways. Determining where the lesion is first, then finding out what it is second is the advocated approach. Further details regarding these structures’ anatomy, blood supply, organization, and neuro-ophthalmic symptoms, as well as the differential diagnosis of lesions affecting them, are detailed in Neuroanatomy of the Afferent Visual Pathway: Overview The Eye and Retina The eyes are the primary sensory organs of the visual system. Before reaching the retina, light travels through the ocular media, consisting of the cornea, anterior chamber, lens, and vitreous. The size of the pupil, like the aperture of a camera, regulates the amount of light reaching the retina. The cornea and lens focus light rays to produce a clear image on the retina in the absence of refractive error, and the ciliary muscle can change the lens shape to adjust for objects at different distances ( accommodation ). Retinal photoreceptors hyperpolarize in response to light. Cone photoreceptors are more sensitive to color and are concentrated in the posterior pole of the retina, or macula, the center of which is the fovea. Rod photoreceptors, more important for night vision, predominate in the retinal periphery. Visual information is processed via horizontal, bipolar, and amacrine cells before reaching the...

Visual Field Perimetry, even though a cornerstone of glaucoma diagnosis, has always been a cumbersome and difficult test to administer as well as undergo. It was the only standard test to assess the functional damage due to glaucoma for several decades and had not evolved much despite rapid advancements in technology. This is now the era of Virtual Reality, and several innovators started to develop head-mounted visual field testing devices derived from gaming headsets including the extremely low-cost Google Cardboard. Virtual Reality is an upcoming field and Perimetry is only one of the aspects of Ophthalmology being advanced by it. The Periscreener VirtualEye Going beyond subjective perimetry where the patient response is a factor, is the Visual Grasp technique of VirtualEye. Indications • Screening Visual Fields • Perimetry in bedridden patients • Portable Visual Fields for those who cannottravel to a center with full scale visual fields • Home based Visual Field Charting • Tele-Glaucoma Procedure The subject wears the Virtual Perimetry headset while seated comfortably. In case the subject is more comfortable lying down or even standing up, that is also acceptable. The subject also holds a wireless clicker to respond to the visual stimuli. The operator activates the headset from their controls on the Tablet computer. This displays a visual acuity test and to which they respond verbally. Then the appropriate visual field test is started. Subject keeps both eyes open and l...

Definition The visual field refers to the total area in which objects can be seen in the side (peripheral) vision as you focus your eyes on a central point. This article describes the test that measures your visual field. Alternative Names Perimetry; Tangent screen exam; Automated perimetry exam; Goldmann visual field exam; Humphrey visual field exam How the Test is Performed Confrontation visual field exam. This is a quick and basic check of the visual field. The health care provider sits directly in front of you. You will cover one eye, and stare straight ahead with the other. You will be asked to tell when you can see the examiner's hand. Tangent screen or Goldmann field exam. You will sit about 3 feet (90 centimeters) away from a flat, black fabric screen with a target in the center. You will be asked to stare at the center target and let the examiner know when you can see an object that moves into your side vision. The object is usually a pin or bead on the end of a black stick that is moved by the examiner. This exam creates a map of your central 30 degrees of vision. This exam is usually used to detect brain or nerve (neurologic) problems. Goldmann perimetry and Automated perimetry. For either test, you sit in front of a concave dome and stare at a target in the middle. You press a button when you see small flashes of light in your peripheral vision. With Goldman testing, the flashes are controlled and mapped out by the examiner. With automated testing, a computer c...

Contents • 1 Summary • 2 The field of vision and characteristics of visual field loss in glaucoma • 3 Devices and Algorithm • 3.1 1st generation FDT perimetry • 3.2 Second generation Humphrey Matrix FDT perimetry • 4 Testing methods • 5 Interpretation • 5.1 Reliability indices • 6 FDT vs SAP • 7 Uses in clinical practice • 8 References Summary Various testing modalities are currently available for detecting visual field loss. This page will focus specifically on the role of frequency doubling technology in assessing visual fields. Frequency doubling technology (FDT) perimetry is based on a flicker illusion created by counterphase flickering of a low spatial frequency sinusoidal grating at a high temporal frequency. The frequency doubling illusion (see example y cells in the magnocellular layer. The field of vision and characteristics of visual field loss in glaucoma The normal field of vision encompasses approximately 50 degrees nasal and superior, 70 degrees inferior, and 90 degrees temporal. Early glaucomatous nerve damage is thought to be due to loss of large-diameter retinal ganglion cells, namely the M y cells of the magnocellular layer. The earliest visual field defects in glaucoma have been described as the nasal step or paracentral scotoma, followed by extension of these defects centrally over time. Hart and Becker have described three phases of glaucomatous nerve damage. Devices and Algorithm The 2 commercial FDT perimeters available are the first generation Frequ...

Clinical perimetry measures the differential light sensitivity, which is a measure of the dimmest light stimulus seen by the patient against the illuminated background. Diagnostic information is enhanced by the program and strategy of the administered test that is built into the machine software. The visual function results need to be measured for reliability and reproducibility to be useful clinically for diagnostics and follow-up. • Fankhauser F, Koch P, Roulier A. On automation of perimetry. Graefes Arch Clin Exp Ophthalmol. 1972:126–50. • Flammer J, Jenni A, Bebie H. The OCTOPUS G1 program. Glaucoma. 1987;9:67–72. • Weber J, Klimaschka T. Test time and efficiency of the dynamic strategy in glaucoma perimetry. German J Ophthalmol. 1995;4:24–31. • González de la Rosa M, Rodríguez J, Rodríguez M. Flicker-TOP perimetry in Normals and Patients with ocular hypertension and early Glaucoma; Perimetry Update 1998/1999. p. 59–66. • Schiefer U. Realization of semi-automated kinetic perimetry (SKP) with the Interzeag 101 Instrument. In: International Perimetric Society (IPS) Meeting. 2002. • Bebie H, Flammer J, Bebie T. The cumulative defect curve: separation of local and diffuse components of visual field damage. Graefes Arch Clin Exp Ophthalmol. 1989;227:9–12. • Visual field Digest 6th Edition 2016, Haag-Streit AG, Koniz Switzerland (ISBN 978-3-033-06001-2). Cite this chapter Rangaraj, N.R., Sathyan, P. (2021). Interpretation of Octopus Visual Fields. In: Patyal, S., Gandhi, M. ...