The ophthalmoscopy itself shows only a very low risk of complications. Due to the pupil dilating eye drops there is an increased sensation of glare and visual acuity is reduced for about three hours. Therefore, the patient should not participate in road traffic and should not operate any machines during this time. In rare cases, the application of the eye drops can lead to an increase in intraocular pressure, which can lead to a glaucoma attack in people with a corresponding predisposition.
Execution/procedure of the ocular fundus mirroring
The performance of an ophthalmoscopy is only possible if there is a clear view into the eye. This means that there must be no clouding of the cornea or the lens of the eye or bleeding into the vitreous body (vitreous humour). As a rule, the patient is first given special pupil-dilating eye drops to facilitate the examination.
The ophthalmologist then uses a magnifying glass to look through the pupil to the back of the eye. To do this, the eye must be illuminated with a bright light source. There are basically two methods of ocular fundus mirroring: direct and indirect fundus mirroring, both of which have their advantages and disadvantages.
When performing a direct ophthalmoscopy, the patient has to fix a point in the distance. The doctor uses his right eye to assess the patient’s right eye (the same applies to the left side). For the examination he has to get very close (up to a distance of about 10cm) to the patient, which is often perceived as unpleasant by the patient.
An electric, hand-held ophthalmoscope is placed between the eyes of the observer and the person being examined, which at the same time contains a magnifying glass, a lamp and a so-called “Rekoss disc” with which refractive errors (errors of refraction) of the doctor and/or patient can be compensated. The image that the doctor sees of the back of the eye is magnified about 15 times, upright and correct to the side. Due to the high magnification, only a relatively small section of the retina can be seen, but many details of the retinal centre, such as the exit of the optic nerve, the yellow spot or the central blood vessels can be closely examined.
Various diseases of the eye itself lead to specific findings at the fundus of the eye, which can be made visible by a fundus mirror. In the case of a retinal detachment, the retina and vessels lie in folds, damage to the optic nerve leads to changes in the papilla and also pigment disorders or tumours can be detected. In the case of increased intracranial pressure, the optic nerve bulges into the interior of the eye.
This is known as a congested papilla, which is characterized by edge blurring and possible bleeding. In glaucoma, an increased ratio of central cavity to peripheral area can often be observed. However, ophthalmoscopy is also particularly important for general diseases such as diabetes mellitus, high blood pressure (hypertension) or vascular calcification (arteriosclerosis).
The typical finding in case of high blood pressure is called fundus hypertonicus, where a pronounced constriction of the vessels and papillary swelling can be observed. Bleeding is often also present. Patients with diabetes show similar vascular changes at the back of the eye, which, if detected early, can be reversed by better blood sugar control. For this reason, both in the case of diabetes and the other diseases mentioned above, ocular fundus endoscopies should be performed at regular intervals.