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Short Wavelength Automated Perimetry (short + wavelength_automate_perimetry)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Ganzfeld changes in short wavelength automated perimetry

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2002
S. Sukumar
Purpose:, The change in perception of background illumination known as Ganzfeld changes occurs while performing perimetry test. It occurs under higher background illumination and whilst covering the non-tested eye with a black patch. We investigated the occurrence of Ganzfeld changes in Short Wavelength Automated Perimetry (SWAP) and assessed the performance while covering the non-tested eye with a standard black patch and with a translucent occluder. Methods:, Twenty-eight volunteers of age 22 ± 3 years participated in the study. A custom made 16-point test was used to analyse the sensitivity with a standard black patch and with the translucent occluder. The number and duration of Ganzfeld changes in each condition were detected by subjective responses. The visual comfort of the subjects under each patching condition was assessed using a comfort scale (0,5) and subject's preference. Results:, Ganzfeld changes occurred when a standard black patch was used and appears to influence the ability to see the test targets. With a standard black patch 5 Ganzfeld changes were observed per minute and it varied between 2 and 8 s. The duration and occurrence increased towards the end of the test. Using a translucent occluder almost eliminates the occurrence of Ganzfeld changes and improved the sensitivity (p = 0.001). Of the 28 subjects, 22 preferred translucent occluder to black patch. Conclusion:, Use of a translucent spectacle occluder over the non-tested eye significantly reduces the Ganzfeld changes and improves the performance in SWAP. [source]

Short wavelength automated perimetry

ACTA OPHTHALMOLOGICA, Issue 6 2001
John M. Wild
ABSTRACT. Short Wavelength Automated Perimetry (SWAP) utilizes a blue stimulus to preferentially stimulate the blue cones and a high luminance yellow background to adapt the green and red cones and to saturate, simultaneously, the activity of the rods. This review describes the theoretical aspects of SWAP, highlights current limitations associated with the technique and discusses potential clinical applications. Compared to white-on-white (W-W) perimetry, SWAP is limited clinically by: greater variability associated with the estimation of threshold, ocular media absorption, increased examination duration and an additional learning effect. Comparative studies of SWAP and W-W perimetry have generally been undertaken on small cohorts of patients. The conclusions are frequently unconvincing due to limitations for SWAP in the delineation of abnormality and of progressive field loss. SWAP is almost certainly able to identify glaucomatous visual field loss in advance of that by W-W perimetry although the incidence of progressive field loss is similar between the two techniques. Increasing evidence suggests that functional abnormality with SWAP is preceded by structural abnormality of the optic nerve head and/or the retinal nerve fibre layer. SWAP appears to be beneficial in the detection of diabetic macular oedema and possibly in some neuro-ophthalmic disorders. [source]

Ganzfeld changes in short wavelength automated perimetry

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2002
S. Sukumar
Purpose:, The change in perception of background illumination known as Ganzfeld changes occurs while performing perimetry test. It occurs under higher background illumination and whilst covering the non-tested eye with a black patch. We investigated the occurrence of Ganzfeld changes in Short Wavelength Automated Perimetry (SWAP) and assessed the performance while covering the non-tested eye with a standard black patch and with a translucent occluder. Methods:, Twenty-eight volunteers of age 22 ± 3 years participated in the study. A custom made 16-point test was used to analyse the sensitivity with a standard black patch and with the translucent occluder. The number and duration of Ganzfeld changes in each condition were detected by subjective responses. The visual comfort of the subjects under each patching condition was assessed using a comfort scale (0,5) and subject's preference. Results:, Ganzfeld changes occurred when a standard black patch was used and appears to influence the ability to see the test targets. With a standard black patch 5 Ganzfeld changes were observed per minute and it varied between 2 and 8 s. The duration and occurrence increased towards the end of the test. Using a translucent occluder almost eliminates the occurrence of Ganzfeld changes and improved the sensitivity (p = 0.001). Of the 28 subjects, 22 preferred translucent occluder to black patch. Conclusion:, Use of a translucent spectacle occluder over the non-tested eye significantly reduces the Ganzfeld changes and improves the performance in SWAP. [source]

A comparison of short wavelength automated perimetry with frequency doubling perimetry for the early detection of visual field loss in ocular hypertension

CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 4 2000
John Landers MBBS
ABSTRACT Background: Achromatic automated perimetry (AAP) is limited in its ability to detect very early visual field loss in ocular hypertensive patients. Tests targeting axons that are selectively damaged, or have low redundancy, may detect visual field losses before they are seen on AAP. It has been claimed that short wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP) are two tests that provide early detection. Methods: Patients (n = 62) were selected on the basis that they had raised intraocular pressure but normal visual fields detected by AAP. A SWAP and an FDP was performed on each of the patients and the results compared. Fields were scored as either normal or abnormal based on criteria used in previous studies. Results: On comparing FDP with SWAP as the ,gold standard', a sensitivity of 88.9% and a specificity of 96.2% was found, showing a high concordance between the two tests. Conclusion: These results suggest that as SWAP may be predictive of AAP visual field loss, FDP may be similarly predictive. [source]