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Low Vision Assessment and Rehabilitation

Initial Low Vision Management

Low Vision Treatment Options

Selection of Aids for Distance Vision

The most practical solution is to move the patient closer to the object. When this is not possible, or inadequate, distance aids must be used.

A variety of options are available for the use of distance vision telescopes. These may be hand-held or spectacle mounted, monocular or binocular, focusable or afocal, and autofocus or manual focus in design. Telescopes or binoculars have the disadvantages of small fields of view (generally the stronger the scope, the smaller the field), exaggerated motion, and decreased light transmission. Therefore, telescopes for distance vision are used for static, not mobile, tasks.

To determine the appropriate level of magnification for monocular telescopes or for binoculars, divide the denominator of the actual visual acuity by the denominator of the desired visual acuity. For example: 20/200 (actual) 20/50 (desired) = 4 X scope. This is an estimated starting point for further refinement.

Besides target size and distance, other important factors such as figure ground perception, background contrast, lighting, and light transmission can affect the practical use of telescopes. Some older persons find telescopes hard to use. When learning to use telescopes, users progress through skill levels, beginning with spotting a stationary object while seated. Developing proficiency requires patience and practice.

  1. Skill level one: While seated, scan for and fixate on a target without the scope. While fixated on the target, bring the scope up to the appropriate eye, reestablish target fixation, then focus the scope.

  2. Skill level two: Complete the sequence of level one, then track the target as it moves left to right, right to left. Next introduce a target moving slowly away from and then towards the viewer; this requires continual refocusing of the scope and may be difficult initially.

  3. Skill level three: While standing, scan for, fixate, focus, and track a slowly moving target. Start with left to right and right to left, then increase the speed of the target. Movement toward and away from the viewer is more difficult and the patient may not attain the same target speed as for side-to-side movements.

Developing proficiency with distance visual aids requires patience and practice.

Dr. Cole was evaluated with telescopes at this initial assessment, but a recommendation was deferred due to their decreased light transmission and because of his contemporaneous unstable vision.

Selection of Aids for Intermediate Distance Vision

Short focusing telescopes or microscopes with low-power caps are the primary visual aids for intermediate tasks, such as keyboarding, playing cards or reading music. As with distance scopes, the small field of view, narrow depth of field, and dependance upon good light levels limits their application to specific tasks.

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Last Update: Nov 29 2012