金台診所醫學美容的部落格

The Humphrey visual field analyser is arguably the world’s gold standard in visual field equipment and is used in most hospital eye departments including Addenbrooke’s. 

A visual field test measures your peripheral vision. It is a painless test that doesn’t involve the use of eye drops. With your head in a static position lights are flashed on and off and you are required to react by pressing a button whenever you see a light. The lights are a mixture of bright and dim at different stages of the test. Some of the flashes are just to check you are concentrating. Each eye is tested separately, and you should allow about 15 minutes to have the whole test. The recommendation for a test is advised at your standard eye exam. It is one of the most important tests for glaucoma as it determines whether you have lost any of your peripheral vision.



Several basic conditions must be met for a successful map of the visual field to be produced by any method. The individual must be able to maintain a constant gaze toward a fixed location for several minutes. Each eye is tested separately while the opposite eye is covered with a patch. Refractive correction must be made with a test lens. Spectacles must not be worn because they can cause false defects in the visual field due to their shape [6]. In addition, correction must be made for presbyopia, to reduce accommodative strain. Standard adjustments for presbyopia are available based on age alone. To correct an astigmatism >0.75 diopters, a cylindrical lens must be used. If the eyelid or lashes obstruct the visual axis, the lid may be taped to the forehead to lift it out of the way.
During Humphrey Visual Field (HVF) testing, the patient places his head in the chinrest and fixes his gaze toward a central fixation point in a large, white bowl. As stated above, this test is an example of static perimetry. It assesses the ability to see a non-mobile stimulus which remains for a brief moment (200 ms) in the visual field. When the patient sees a presented stimulus, he presses the button on a handheld remote control. Different locations within a given region of the visual field are tested until the threshold, or the stimulus intensity seen 50% of the time, is seen at each test location. 
Stimuli vary in size and luminous intensity. Goldmann size III (about ½ degree in diameter) is generally used, but Goldmann size V (approximately 2 degrees in diameter) is available for patients with decreased visual acuity (< 20/200) or other visual impairment. Goldmann sizes I, II, and III are rarely used clinically. The luminous intensity of the stimuli can be varied over a range of 0.08 to 10,000 apostilbs (asb). It is reported in decibels (dB) of attenuation, or dimming, extending from 0 dB (the brightest, unattenuated stimulus) to 51 dB (the dimmest, maximally attenuated stimulus). If the patient is unable to see even the brightest, unattenuated stimlulus, it is reported as <0 dB.
The Swedish Interactive Thresholding Algorithm (SITA) is frequently used. SITA is a forecasting procedure that uses Bayesian statistical properties that is similar to the methods used for providing weather information and predictions. SITA allows for more rapid analysis than would be possible without forecasting. By taking into account a user's results in nearby locations, stimuli that are unlikely to be seen, or extremely likely to be seen are not tested exhaustively. Instead the stimuli that are likely near threshold are tested. 



Field of vision - Introduction video 

How to read Humphery's visual field report ? part 1 video 

How to read Humphery's visual field report ? part 2 video 

How to read Humphery's visual field report ? part 3 video 

How to read Humphery's visual field report ? part 4 video 

How to read Humphery's visual field report ? part 5 video 

How to read Humphery's visual field report ? part 6 video 

How to read Humphery's visual field report ? part 7 video