The retina is for the eye what the film is for the camera; the retina generates the pictures which are – via the optic nerve – passed on to the brain and perceived as such by it.
The retina consists of many million sensory cells (photoreceptors) which increase in numbers from the outside to the centre; the centre of the retina (macula) has the highest density of sensory cells.
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a) diseases in the region of highest visual acuity
According to its extremely high efficiency, the centre of the retina is especially sensitive and, not rarely, exposed to an age-related process of wear (dry macular degeneration), which in most cases, due to a decline of sensory cells, leads to a more or less perceptible diminishing of visual acuity; however, as a rule, it does not jeopardize the reading capability as such. So far, no cure is known that would surely be effective against the dry macular degeneration.
In certain cases, the macular degeneration takes a different, more aggressive course (exudative macular degeneration), in which blood components are issued under and into the centre of the retina causing a loss of its function within a few weeks' time. The exudative macular degeneration may be heralded by distorted vision, i.e. that the patient does not see straight lines as straight any longer; later on, a zone of blurred vision is perceived in the centre of the visual field until eventually only a grey spot is to be seen at the place one is just trying to look at.
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Exudative macular degeneration
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When it has freshly occured , the exudative macular degeneration is an emergency; patients who notice the aforementioned symptoms should see an ophthalmologist the next working day and insist on an examination of the ocular fundus with the pupil dilated, because the exudative macular degeneration is treated the better the sooner it is noticed.
Various methods of treatment are available:
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laser coagulation |
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thermotherapy
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local treatment with drugs (PDT, photodynamic therapie)
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operative treatment (macular translocation)
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The question which treatment is the most appropriate in the respective case can only be decided in a thorough examination of the eye.
b) diabetic retinal disorders; other circulatory disturbances
Diabetes mellitus is a disease which may detrimentally affect the entire body. With the disease advancing, the eyes are disproportionately often affected; after fifteen years of duration of the disease, every second diabetic has diabetic retinal findings (diabetic retinopathy).
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Early diabetic
retinopathy
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Severe diabetic
retinopathy
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There are two distinct pathogeneses, though often overlapping and sometimes negatively complementing each other:
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in its original meaning, the diabetic retinopathy affects the retina as a whole and distinguishes itself by circulatory disturbances; some blood vessels become porous and leak, others occlude. If it comes to a decreased blood circulation of major regions of the retina due to the disease, new blood vessels grow onto the retina (neovascularizations), which may cause spontaneous haemorrhages into the eye, a retinal detachment and, finally, complete blindness of the eye. |
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the second pathogenesis affects the centre of the retina (diabetic maculopathy); due to either the flow of humour out of diseased blood vessels or their occlusion, a swelling of the macula occurs with a progressive loss of visual acuity. Nevertheless, diabetic maculopathy alone never causes complete blindness. |
Continue reading (diabetic retinal disorders, other circulatory disturbances of the retina, retinal detachment and related problems)
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