Ophthalmological examinations

The focus of this text is assessment of vision of visually impaired, deaf or profoundly hearing-impaired individuals. Thus, the emphasis is low vision examinations which are easier for the interpreter because the room lights are not switched on and off during the examination and there usually is more room than in many regular offices. However, we must be prepared for both situations.

Doctors are responsible for the quality of examinations in their offices and also communication. However, if the ophthalmologist is not trained in the examination of deaf persons and the deaf patient does not dare to require proper communication, the interpreter is more than usually in charge of the quality of communication. Before the examination starts the doctor and the interpreter have to find out what kind of accommodation has to be made in terms of vision loss.

Establishing the communication

When the interpreter establishes communication with a new patient in the waiting area, three important variables are observed:

  1. preferred distance for communication,
  2. size of the communication field and
  3. sensitivity to light.

The same three variables are checked in the examination room. The preferred distance is usually easy to find, although sometimes it is difficult to find a space for a chair at that distance. A stool on wheels is handy as the interpreter's chair because there is often a need to relocate during the examination.

Communication field is described in a very confusing way in all published guidelines for deafblind interpreting. In order to understand how changes in visual field limit communication we have to think about the two most common types of loss of visual field: tunnel vision and central scotoma.

"Tunnel vision" gives a somewhat wrong impression of the constricted visual field of patients who have advanced retinitis pigmentosa, choroideremia, or glaucoma, to mention some of the most common causes of small central field. The residual field is often 10-15 degrees in diameter which means that it is 10-15cm (4-6 inches) in diameter at 57cm (22 1/2 inches, 20-30cm in diameter at 114cm, 40-60cm in diameter at 228cm, 10-15 metres at 57 metres and so on. The further away from an object the person with tunnel vision is, the more he can see of it (Figure 6). "Tunnel vision" is not a tunnel but a cone that opens up at a distance.

Figure 6. "Tunnel vision" of 15 degrees means that the person sees within 15 degrees of visual angle without moving the eyes. The area available for signing increases the further away the person signing is sitting.

At the beginning of the examination the area in space seen by the patient can be measured using the technique demonstrated in the videotape: the patient looks at the interpreter's nose and reports when the right hand appears from the right, then the left hand appears from the left, and then from above and finally the right hand from below. If the interpreter touches his body at the points where the communication field ends, he gets a good reference for the size of signs to be used.

The sign for tunnel vision is as misleading as is the written name. We might consider renaming this type of visual field. In sign language it is easy; the sign can be cone-shaped rather than the shape of a cylinder which is typically used.

Central scotoma means a loss of visual function in the middle of the visual field. Since it causes loss of visual acuity, contrast sensitivity and often also changes in colour vision, the person signing has to be closer in order to compensate for the vision loss. It may feel awkward to sign very close and it is often difficult to read the patient's signs at that short distance but during examination there is no other alternative. However, if there is a long discussion between the doctor and the patient and the patient is accustomed to using binoculars, they could be used. Then the interpreter sits at a longer distance that has to be defined.

If the central vision is still good, a low power telescope can be used reversed, i.e. as a minifier, to increase the field. Groups of Persons with Usher Syndrome sometimes cause perturbation in other tourists when they use their telescopes both ways: first backwards to increase the field and get some overview, and then the right way to see details.

Demonstration glasses for field defects

Since it is so difficult to imagine the effect of either tunnel vision or central scotoma, demonstration glasses are often found to be helpful by interpreters, parents and teachers. Demonstration glasses for tunnel vision are made by glueing six short strips of translucent tape to form a triangle (Figure 7). The size of the central triangle is found by trial and error. When you have made the first one, place it on a pair of eyeglasses, look at a piece of white paper at exactly 57cm distance, and mark the area seen through the central opening. The diameter (in centimetres) of the area seen gives you the diameter of the visual tunnel in degrees. You will also have some peripheral vision, much like a patient with retinitis pigmentosa.

Figure 7. A. Demonstration glass for “tunnel vision” of approx. 15 degrees (the right lens). The demonstration device is made of a double layer of adhesive tape in order to prevent it from adhering to the glasses. The tape triangle can be fixed on a pair of glasses with small, additional pieces of tape to adhere the demonstration device on the frame.

B. Demonstration glass (the left lens) for central scotoma: a small piece of adhesive tape, approx. 0.3 cm in height and 1.0 cm in horizontal diameter, causes a large central scotoma. The depth of scotoma is related to the thickness of the tape. This is about the smallest central scotoma that untrained observers can use when reading. It should be glued on clear cling film with a small oval piece of clear tape and placed on the glasses at the optical centre. Then there is enough blurred area even during reading saccades. Smaller "scotomas" lead to peeking but they should be shown briefly to demonstrate the real size of the scotoma that the patient has if it is smaller. This demonstration scotoma usually explains the effect of magnification; it just disappears when magnification is sufficiently high, i.e. when the visual system can extrapolate over the scotoma. Note that these demonstration glasses are best used monocularly; the other eye should have translucent occlusion.

A central scotoma can be demonstrated in a similar fashion by using a small piece of tape in the middle of the glasses and by asking the person to look through that area and not to peek around it (Figure 7). The tape would leave markings on the centre of the glasses so it is best to use cling film between the lens and the “central scotoma".

Diffuse loss of vision due to opaque media (cataract, cloudy cornea or cloudy vitreous) is easy to demonstrate by using Glad Wrap or a similar plastic wrap, folded eight to ten times. When folding, let small wrinkles form in the material so that you get an uneven loss of information in different parts of the image.

Illumination during examination

Regular bright room illumination is usually adequate for communication. If the lights have to be turned down or off, explanations about what is going to happen must be signed beforehand if the patient is not accustomed to tactile communication.

When the lights are turned on there may be a short period during which the patient cannot see signs well enough, so again some time is lost in waiting for the communication to start.

The walls of many offices are white and therefore not a particularly good background behind the interpreter. If it is possible to arrange a neutral-colored screen behind the interpreter, it may be extremely helpful for many patients. RP-patients with advanced retinal degeneration often complain that an interpreter signing in front of a lightly colored wall may suddenly disappear in a whitish cloud for several seconds. Many patients do not want to interrupt by telling about the disturbance in vision, not knowing that the ophthalmologist would be very interested to learn of it.


Recommendations regarding clothing are especially important when interpreting to a visually impaired-hearing impaired person who may be easily dazzled by white or shiny clothing or jewellery. Clothing with stripes or checks may disturb also. Optimal contrast helps the patient to see the signed information and therefore dark shirts with half long or three-quarter length sleeves are best. A dark smock with big pockets is especially useful because the interpreter will often move from room to room and will not want to be concerned about a purse and other belongings.

What is said about the interpreter's clothing is equally true for the doctor's clothing. The customary white coat may dazzle the patient. In Europe, many specialists in low vision use dark clothing in the office.

Relocating in the office

During the examination there are several situations where the interpreter has to move, either to see the patient's finger spelling as during measurement of visual acuity at near or to be aligned with the gaze of the patient when the microscope is used.

The offices have not been designed with tactile communication in mind; quite often the interpreter has to squeeze between the instruments in uncomfortable positions, even kneeling on the floor in order to continue communication. If it is possible to use a large room for examination of handicapped patients, it will make the interpreter's work much easier.

As in any communication setting, the interpreter should sit close to the doctor, slightly behind him when visual signs are used. This makes it easier for the patient to change fixation between the doctor and interpreter.

Guiding the patient

Visually impaired, deaf patients cannot orient in a strange place and need help when moving in the examining room or from room to room. It will help the patient to orient in the room if the interpreter can describe the room and the instruments briefly when the patient enters.

Guiding visually impaired persons is something that everyone working in an eye clinic should know, doctors and interpreters alike. If the personnel has not been exposed to training in guiding techniques, the local mobility instructors can arrange a short demonstration with one or two of the deafblind patients.


During examination of vision there are natural pauses; these occur often enough that it is possible to interpret without a break during a complete eye examination. If laboratory tests are done afterwards there is usually some waiting time. Patients accept being left alone for a while if the interpreter informs both the patient and the receptionist where he will be found if needed before the next test.


Many interpreters work as freelance interpreters. Therefore it is a real problem if they have to wait for the examination. If three deaf blind patients can be scheduled in one morning it saves the interpreter's travelling time. Deaf blind persons seldom meet with each other and may appreciate the opportunity of chatting with another deafblind person in the waiting area. The time needed for dilatation of pupils will be used in communicating with the other deafblind patient and the interpreter is not needed in the waiting area.