Introduction
The visual field is the area that we can see “in one glance” when the eye fixates on a certain point. There are various causes for the loss/partial loss of the visual field. In this chapter we will consider the way in which the visual field can generally be examined, on the basis of three patients who are affected by this problem. In an ophthalmology clinic more specialised methods are available to investigate the degree of the defect and the loss of function in more detail.
The questions that are asked in the history-taking originate from the so-called prediagnosis. Ask yourself, in connection with the hypothetical causes of the symptom, which other phenomena could occur.
Loss (or partial loss) of the visual field often originates from defects of the retina, damage to the conducting trajectories, the optic nerves (see also “The Neurological Examination”), or the part of the visual cerebral cortex where the information that is received from the relevant part of the visual field is processed.
The following questions should be asked in the history-taking.
- How old is the patient?
- How long have the problems existed?
- Have the problems developed suddenly or gradually?
- Besides what the patient describes, do they also see blotches, flies, light flashes, stars, imagery, or curtain-like phenomena?
- Does covering one eye change the situation?
- Was there any trauma to the eye or head prior to the start of the problems?
- Has the patient experienced any headaches prior to the symptoms developing?
- Has the patient or the people close to them ever noticed if, lately, they have been momentarily ‘absent’ for a short period or have had a short-term loss of strength?
- Are there any symptoms that are the result of hormonal changes, such as breast formation in men, increased development of mammary gland tissue in women, potentially accompanied by the secretion of milk-like fluid, changes in pubic hair growth, changes in menstrual cycle, changes in libido?
Required materials
- cover patch for the eye of the examiner and/or patient
- Amsler grid
Cover patch for the eye of the examiner and/or patient [Figure 29]
Some people have problems closing one eye at the time. Since this is required for this examination, the eye that is not being tested and thus must be closed, will have to be covered with a cover patch.
Figure 29
Amsler chart [Figure 30]
This consists of a black card with a white grid pattern. In the middle of the grid there is a white dot. During the examination the patient needs to fixate on this dot.
Figure 30