The "central" fields correspond to the area on which one is currently focusing. Sometimes the terms 'focal', 'foveated', or 'macular' vision are used. The area corresponds to the middle 2 percent of your field of view from the extreme left to the extreme right, or about the width of a word or two at arm's length. This area is where visual acuity is best, and it is heavily involved in reading and many near point visual activities.
Within optometry and ophthalmology, central field impairments are most frequently monitored with macular degeneration,a condition which afflicts many older persons and is assessed using the Amsler Grid. Deficits produce apparent distortion of and gaps in the lines.Unfortunately, these procedures rarely demonstrate the central field impairments which are caused by brain injury (which is why alternative procedures have been needed). Indeed, following brain injury, the macular fields are erroneously thought to be 'spared.'
The impact of central hemi-field impairments have not been commonly recognized (in marked contrast to peripheral hemi-field impairments); and, yet, our research with the central computerized functional visual field assessment procedures in this software package brings them out clearly in some people after brain injury.
Central field impairments are most noticed in near-point tasks, especially reading, math, bookkeeping and working with charts and tables. The procedures in CENFIELD are designed to differentiate lateral patterns of impairment.
Central hemi-field impairments are most evident in consistent patterns of misreading. Substitutional errors ("grain"for BRAIN) are more common than truncational ones ("rain" for BRAIN). Two of the tasks in this package involve reading: Error Detection and FASTREAD.
Because central hemi-field impairments can co-exist with aphasia, non-language tasks are needed to make a differential diagnosis and treatment for this group. Two CENFIELD programs (MATCH and INSPECT - Shape Matching and Inspection) are completely non-verbal.
Central hemi-field impairments affect a person's ability to read accurately and to perform close work accurately. Three tasks are included,one of which is nonverbal (MATCH) and two of which involve reading (Error Detection and FASTREAD). The "central" fields correspond to the area on which one is currently focusing. Sometimes the terms 'focal, ''foveated,'or 'macular' vision are used. The area corresponds to the middle 2 percent of your field of view from the extreme left to the extreme right, or about the width of a word or two at arm's length. This area is where visual acuity is best, and it is heavily involved in reading and many near point visual activities.
Within optometry and ophthalmology, central field impairments are most frequently associated with macular degeneration, a condition which afflicts many older persons and is assessed using the Amsler Grid. Deficits produce apparent distortion of and gaps in the lines. Unfortunately, these procedures rarely demonstrate the central field impairments which are caused by brain injury (which is why alternative procedures have been needed).
Indeed, following brain injury, the macular fields are thought commonly to be 'spared.' Central hemi-field impairments have not been commonly recognized(in marked contrast to peripheral hemi-field impairments); and, yet, our research and the central computerized functional visual field assessment procedures in this software package brings them out clearly in some people after brain injury.
Central field impairments are most noticed in near-point tasks, especially reading, math, bookkeeping and working with charts and tables. Two of the tasks in this package involve reading: Error Detection and FASTREAD. One(MATCH - Shape Inspection and Matching) is completely non-verbal.
Central hemi-field impairments are most evident in consistent patterns of misreading. The procedures in CENFIELD are designed to differentiate lateral patterns of impairment. Substitutional errors ("grain"for BRAIN) are more common than truncational ones ("rain" for BRAIN). These will also be seen in FASTREAD.
The computer flashes a word and asks that it be typed in. The task speeds up as long as one can keep up, and slows down after errors. Word lists come with the program; custom word lists can be created with a text editor. The program is included as a brief visual memory exercise, but it also is useful for persons with deficits in attention, foveal perception, and verbal apraxia(difficulty planning and articulating words). The task offers feedback for visual imperception, reinforces attention and alertness, and exercises the typing and production of words. A "copy" mode is also an option.
Error Detection in Texts is a paper-and-pencil proofreading exercise designed to assess attention and, especially, central hemi-field impairment, which is otherwise difficult to diagnose and can interfere with near point activities.This task has proven to be very sensitive to lateralized impairments of the central visual hemi-field. Part of the sensitivity derives from the fact that the individual is NOT required to read out loud, and, therefore,is induced to read quickly. This task is also useful to assess the ability to sustain an independent work effort, as well as to evaluate the ability to detect errors.
The scoring procedure tabulates errors detected to the right, center and to the left. A sample form is shown below:
ANTEATERS Anteaters' tongues are 18 inches long. They don't have any teetb, but they don't need any. Their mouths are long like a tube to contain this interesting fongue. An anteater doesn't just eat ants; it eats many kinds of insects fhat live in the ground, under rocks, and in trees. It uses the third digit on its foot to dig lnto nests of insects. This toe has a very powerful claw on it that makes it easy for the anteater to break intc termites' mests. Once it has dug open a nest it uses its aticky tongue to trap the insects. The largest anteaters live in Soutb and Central Americs. They can be up to four feet long, not including the tail which can also be 4 feet lony. The animal is completely terrestrial vhich means it never goes in the waten. It can live for a long time without eating.
This task was designed to diagnose foveal hemi-imperception using non-verbal materials. Following brain injury, lateralized visual hemi-imperception is not uncommon. If the central (perifoveal) visual fields are involved,reading and focused visual work may be impaired. The purpose of MATCH is to identify any possible lateralized impairment in the perifoveal fields.
Two detailed geometric figures are displayed one above the other.The patient has to decide whether the shapes are the same or whether they differ in some small way. Decision times are reported for left, right and both sides different. Samples below; left - different, right - same.
INSPECT calls for the inspection of two nearly identical shapes to locate a small difference on either the left or right side of the shape. Like MATCH, it is an exercise which addresses central field hemi-imperception in a non-verbal manner.
The purpose of INSPECT is to offer practice in making discriminations in the central visual field, with feedback based on laterality. Some persons will have a lateralized hemi-imperception following an acquired brain injury. An important issue is the extent of visual involvement and, especially, the central (perifoveal) field. INSPECT is a simple form discrimination in which there is always a difference: the issue is which side is it on? The patient must be able to press the corresponding left and right sides of the mouse buttons.
A further level of complexity is offered with INSPECT: if the stimuli are reversed(black on white) the response keys are reversed. Since lateralized differential response often has an attentional component, the response differential may be exaggerated under these more complex conditions.