Thanks to the eye mirror the ophthalmologist can look at the retina in the eyes through the pupil. In order to be able to see as much as possible, it is necessary to make and keep the pupil as large as possible. Special drops have such an effect on the iris, that the pupil becomes large and prevent the pupil from getting smaller again, despite the bright light of the ophthalmologist. This bright light comes from a lamp in the grip of the eye mirror and shines into the eye by means of a mirror. The drops do not only have an effect on the size of the pupil, but also on the muscle that varies the refraction power of the lens. By disabling this, reading will be difficult or impossible for some time after the application of the drops. It is advised to wear sunglasses after this examination. 

Usually the colour of the papilla is yellow-red. Drop-out of the rods and cones goes hand in hand with a change of the nerve fibres of the dropped out cells and this is noticeable as a change of colour of the papilla. Initially, the papilla becomes paler and in extreme cases eventually as pale as wax. From the papilla the blood vessels are spread across the retina. Sometimes the blood vessels are narrower than they usually are. This is, just like the disappearance of nerve fibres, another consequence and not a cause of the disease. Then the ophthalmologist will pay attention to the retina. By making the eye of the patient look in all directions, an image can be obtained from the entire retina through the widened pupil. The typical pigment accumulations, which have given retinitis pigmentosa its name, will become visible. The pigmentations form black-brown fanciful figures, often compared with crow’s feet or trabeculations. 

The adaptation to the dark is a measure for the speed with which the retina can adjust itself to the various light intensities in the surroundings. Everyone knows that when stepping from a brightly lit room into a dark room, you initially do not see anything. However, the objects in the dark room will slowly but surely become visible. The time that the eye needs to adjust itself as well as the smallest amount of light that one can still see in the dark are measured by the test of adaptation to the dark.
The examination is done with the help of a similar sphere as with the field of vision examination. Again, one eye at a time, the head in the support and continuously looking at a small light in the centre of the sphere. Initially, the inside of the sphere will be brightly illuminated. Then the light in the sphere is turned off (but not the central light that you are to look at). You step as it were into a dark room. Now a test light is offered, just next to the central light. You have to indicate again whether or not you see the light. Just after the light was turned off a bright light is required to make you see it. The longer it has been dark, the faster you will be able to see a weaker light. The eye adjusts itself to the dark. Although the test light will be weaker and weaker, it will still be seen until the limit is reached of the part of the retina that is being examined. 

Seeing in the dark depends on the functioning of the rods. With people suffering from Usher Syndrome and retinitis pigmentosa, whose rods have been affected, the result of this test of adaptation to the dark will probably be upset. Both the speed with which the adaptation to the dark takes place and the eventually reached limit value will be deviating. The adaptation to light/dark will take place much slower and the light intensity of the test light that will eventually be just observed is higher, which is to say that the tested part of the retina is less sensitive. People with an upset test for adaptation to the dark will usually suffer from night-blindness 

Retina with pigment accumulation