HEINE LAMBDA 100 Manual De Instrucciones página 7

Operation
Always dim the room light before examining. Eyes with opaque media should always
be dilated. This is not necessary where no opacity is present. Explain to the patient
as clearly as possible what he will see with the help of the retinometer instruction card
supplied with the set. Use the better eye first to get the patient used to the instrument.
Make sure that the patient is in a comfortable position. He should look into the far
corner of the darkened room.
Switch on the retinometer. If preferred you can set the desired brightness by shining
the light into your own eye. (It may be necessary to change the brightness during the
examination).
Use the lever (3) to choose the pattern of lines and select a low visual acuity value with
the selector wheel (4).
Rest the retinometer upright against the patient's forehead and direct the red light
beams onto the pupil. At the normal reading distance look alongside or over the top
of the retinometer (there is a "window" (2) built into the brow rest (1) and observe the
points of light on the patient's cornea.
Move the beam over the pupil by slightly turning or tilting the retinometer until the
patient recognizes the lines with the red and black pattern. Agree with the patient how
he will indicate the pattern of lines (with a hand-movement or verbally). If he mentions
circular spots or distorted lines, this could be an indication of a malfunction of the
macula.
Change the pattern of lines by rotating the lever (3) with your free hand without moving
the retinometer.
Increase the visual acuity value until the patient is no longer able to recognize the
direction of the lines. The last value which he was able to recognize represents the
potential acuity.
General Instructions for acuity-testing with the Retinometer:
Testing potential acuity with retinometers has been the method of choice for some
years especially where opacities are present. It is usally possible to get very reliable
results provided a few basic preconditions are observed: With very dense opacities
below an optotype visus of 0,1 the reliability of the estimate is reduced, the post-
operative visus is often better than that obtained by the retinometer. With amblyopic
eyes, the tendency is more towards false positives because of the size of the test
pattern. With ametropy of more than 6 Dpt. the results can be improved by examining
the patient while he is wearing his glasses. The same comments apply to high astig-
matism. Further factors which can have a negative influence on the results are nys-
tagmus, tremor, communication problems, senility or debility of the patient. Generally
speaking, degenerative conditions can cause considerable problems, which can only
be overcome if the examiner has the necessary experience of this technique.
(A detailed presentation on the topic, including references, can be found in: Lachen-
mayer, Potentielle Sehschärfe bei Störungen der brechenden Medien [‚Potential visual
acuity in case of breaking media impairments'], Quintessenz-Verlag Munich 1993).
The HEINE retinometer are intended for a transient examination < 2 min. with a 15-minute
break before the next application.
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med 2214 2020-06-02