Preparation For The Examination: Pupil Dilation
Prior to the examination, dilate the patient’s pupil by dropping mydriatics into the eye. Ask the patient to wait for 15 to 30 minutes, until the mydriatics have an effect.
Procedure
For the purpose of this program, the examination using a hand-held funduscope will be described.
– When the pupil is sufficiently dilated, ask patient to sit on the examination chair.
– If the patient wears contact lenses, ask what strength the correction is.
– Glasses must be taken off.
– The correction is adjusted using the optic disc of the funduscope. This allows the examiner to conduct the examination with an unaccommodated eye.
– Sit on a stool and adjust the height so the eyes are at the same level as those of the patient.
– Position yourself so that you do not have to lean forward during the examination.
– Lean backwards slightly, to see the eye in front of you through the funduscope.
– During the examination, hold the funduscope in front of your right eye when examining the patient’s right eye, and vice versa for the left eye.
– If you have profound dominance or amblyopia of one of your eyes, you can proceed by asking the patient to lie down on the examination table. Stand at the head end of the examination table, behind the patient, and conduct the examination whilst standing over the patient and holding the funduscope in front of your dominant or good eye [Figure 73].
Figure 73
– Ask the patient to look into the distance with the other eye.
– Move your head and funduscope in a manner that allows you to reach a distance where the patients’ pupil lights up red [Figures 74, 75].
Figure 74
Figure 75
– Zoom in to the red patch. You will see the outlines of the blood vessels.
– You will first see the papilla, from where the vascular tree originates. If not, follow the vessels in the direction of the sites where the branches merge. Eventually, you will reach the papilla.
– Assess the papilla. Pay attention to the depth of the cup and the cup/disc ratio (normally 3/10 to 6/10). Assess the colour.
– Starting from the papilla, follow the vascular tree in the four directions. You will see vessels running in parallel: the thicker, darker retinal vein together with the narrower, lighter retinal artery. Assess the course of the vessels (slightly meandering, extremely wiry, extremely straight), the branching of the vessels (V-shaped, sharp or blunt, T-shaped), obstructions in the trajectory of the vessels – causing bloodstream blockage, dilations of the vessels, crossing of the vessels.
– When examining the retina, look through the vitreous body. Observe whether the vessels grow in from the retina into the vitreous body. Look for any bleeding or white, cloudy structures.
– Return to the papilla and ask the patient to look into the light. You will be able to see the macula. This is located just temporally from the papilla. Characteristic of this structure is the lack of any vessel structures. In the middle, you will see a small, bright spot light up. In general, the colour of the macula is a bit more intense than that of the surrounding retina [Figure 76].
Figure 76
Figure 77: Image Seen Through A Funduscope.