Ocular Diseases
This page aims to provide information in simple language about various eye diseases. Knowing about diseases and flavours is important for your health. In the event of illness, this information should never replace a medical consultation.
Refractive defects (myopia, hyperopia, astigmatism, presbyopia, diabetic retinopathy).
The most common visual problems are refractive defects. These refer to a set of alterations in which there is inadequate focussing of images on the retina. The vast majority are easily corrected with glasses or contact lenses. In rarer cases, surgery may be an option.
It’s important to know that:
many changes in vision are not refractory defects (various eye and non-eye diseases lead to visual disturbances); some refractory defects can be caused by certain diseases that only an ophthalmologist can properly assess.
Myopia – This is a situation in which the image is focussed in front of the retina and translates into difficulty seeing in the distance. A short-sighted eye is usually larger than normal and is more prone to certain diseases (e.g. glaucoma, retinal detachment, etc.) that receive special attention from an ophthalmologist.
Hyperopia – A defect selected for its difficulty in seeing at close range. It usually causes eye fatigue and even headaches when working closely or reading, due to the increased recovery of focus in the required eyes.
Cataracts
What is a cataract?
Any change in the transparency of the lens (see Normal Eye) is called a cataract.
What causes cataracts?
They are most commonly caused by normal ageing, but can also be caused by a variety of other factors, such as trauma, chronic eye diseases or systemic diseases (affecting the whole body) such as diabetes.
What are the symptoms of cataracts?
Usually, a cataract results in blurred vision, but there are several other symptoms that may indicate its presence. The diagnosis should always be made through observation by an ophthalmologist.
How are cataracts treated?
The main treatment for cataracts is surgery. Cataract surgery involves removing part of the clouded lens and placing an ‘artificial lens’ inside the eyeball (intraocular lens) to restore vision. There are several ways to perform cataract surgery, but the most effective and advanced is called phacoemulsification.
Glaucoma
What is glaucoma?
Glaucoma is a disease of the eyes that results in a progressive increase in eye strain, leading to a decrease in vision (which can result in blindness). There are several types of glaucoma, but the most common (and the one to which this text is dedicated) is open-angle glaucoma.
Why does eye strain rise?
There is a transparent liquid that circulates inside the eyeball (aqueous humour). In people with glaucoma, and for reasons that are not yet widely understood, this liquid begins to have difficulty leaving the eyeball, causing an increase in eye strain.
What are the symptoms and dangers of glaucoma?
Increased eye strain, if not detected and treated, leads to the slow and progressive ‘death’ of the nerve responsible for vision (the optic nerve). These changes cause a loss of vision (especially our field of vision). Glaucoma shows symptoms at an advanced stage of the disease and changes in vision are only felt by the patient when the optic nerve has already suffered serious and irreversible damage.
Strabismus
The term strabismus is used whenever there is an eye disorder. This problem usually occurs in children and can be present in many of them at birth. It is very important to diagnose and treat this condition when a child is still young, otherwise the vision in one eye can be irreparably impaired. A child with strabismus tends to use the deviated eye less or less, which becomes ‘lazy’. This reduced vision is called amblyopia.
Strabismus can be constant or only appear at certain times. The eyes can be deviated inwards, outwards, upwards or downwards. These deviations can also be associated.
The persistence of an ocular deviation in a child aged 4 months requires an ophthalmological examination. It is also recommended that all children have an ophthalmological examination by the age of 6 months.
Strabismus can also appear in adults due to illness or trauma.
Diabetic retinopathy
Diabetes is a disease in which, among other changes, there is an increase in ‘sugar’ in the blood. This lack of control can damage various areas of the body. The eyes are one of the organs that can be seriously affected, although there are no major symptoms. Diabetic retinopathy is an ocular manifestation of the disease and one of the main causes of blindness. To avoid blindness, blood sugar levels (glycaemia) need to be controlled as well as possible from the earliest stages of the disease.
An increase in diabetic retinopathy results from changes in the small blood vessels of the retina inside the eye. In some cases, abnormal vessels develop in the retina. These vessels are very fragile and bleed easily, leading to the formation of fibrous tissue that pulls on the retina. This stage of the disease is very serious and causes proliferative diabetic retinopathy.
Diabetics should have their eyes checked regularly for changes caused by diabetic retinopathy. Sometimes laser treatment is necessary. Remember, however, that the best treatment for alterations is to try to avoid further treatment with your health and, if you are not diabetic, with the institution of a lifestyle regime that allows or controls the disease
Source: Portuguese Ophthalmological Society
Age-Related Macular Degeneration
What is AMD?
In AMD there is damage to the macula, a small area at the back of the eye that allows small details to be seen clearly. When a macula doesn’t work properly, the patient can’t, for example, read or thread a needle. Although macular degeneration reduces vision in the central part of the retina, it does not impair vision in the side or periphery of the eye. The patient can see the outline of a clock, but cannot see the time. Macular degeneration on its own does not result in total blindness, as people still have peripheral vision and are able to look after themselves.
What causes specialised age-related macular degeneration (AMD)?
AMD can arise as part of the body’s natural ageing process. There are two most common types of AMD: the atrophic form and the exudative form.
Atrophic AMD:
Most people have atrophic AMD. It accounts for 80 to 90 per cent of all cases of AMD and is responsible for around 10 to 20 per cent of all cases of marked vision loss. It is due to the ageing of the tissues of the macula. Vision loss is usually slow.
Exudative AMD:
Exudative AMD accounts for only 10 to 20 per cent of all AMD cases. It is responsible for 80 to 90 per cent of cases of severe vision loss. It results from the formation of new blood vessels in the back of the eye (neovessels). These new blood vessels leak fluid or blood and incorporate the central vision. Vision loss can be rapid and severe.
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