Eye diseases and vision defects
Some refractive errors and eye diseases tend to appear in childhood, while others are more typical of older people. Some are seen mainly in developed countries, while others cause blindness in less developed parts of the world, where access to the necessary medical care is limited. It is important to distinguish between refractive errors (vision defects) and eye diseases.
Refractive errors
Refractive errors are the most common cause of impaired vision. A refractive error occurs when parallel light rays entering the eye do not converge on the retina after refraction. Refractive errors are corrected with optical aids – prescription glasses and contact lenses – or eliminated by one of the laser eye surgery methods. With selected laser eye procedures, it is even possible to correct all of the eye's refractive errors in a single procedure.
Short-sightedness
(myopia)
Short-sightedness is the most common refractive error and causes blurred vision of objects at a distance of 5 metres or more. The blurred image is caused by light rays being focused in front of the retina.
In Slovakia, approximately 20% of adults are short-sighted. Myopia most often begins to develop in school-age children and worsens most markedly during adolescence. Short-sightedness is most prevalent in developed countries. Besides heredity, lifestyle therefore also plays a significant role in its development – frequent and prolonged use of mobile devices and computers, and a lack of physical activity and time spent outdoors.
Long-sightedness
(hypermetropia/hyperopia)
Z-Lasik Z 3D is an enhanced version of the Z-Lasik method. The refractive procedure follows the same steps, but with a technical improvement. The state-of-the-art femtosecond laser allows the angle to be set even more precisely, and the correction is performed in three-dimensional rather than two-dimensional mode, as is the case with the Z-Lasik method. This innovative technology ensures maximum safety and an eye operation whose result is visible immediately.
The Z-Lasik Z 3D method is considered the gentlest, fastest and most precise femtosecond laser procedure available today for correcting short-sightedness, long-sightedness and astigmatism.
Astigmatism
Unlike short-sightedness or long-sightedness, astigmatism is caused by an uneven curvature of the cornea, as a result of which light rays are refracted differently in areas with different curvature. People with astigmatism therefore see part of the image blurred or hazy.
Astigmatism is corrected with glasses or contact lenses with toric optics, which contain a so-called cylinder to refract light. As with short-sightedness and long-sightedness, the only way to get rid of astigmatism permanently is laser eye surgery.
Presbyopia
(age-related long-sightedness)
Presbyopia is a vision defect that affects everyone, most often between the ages of 40 and 45. It usually appears earlier in long-sighted people and in people who have not previously had any refractive errors, and somewhat later in short-sighted people. It can be classed as an age-related vision defect, as it is linked to the natural ageing of the eyes, specifically of the lens. With age, the lens loses its ability to accommodate, which shows as an inability to focus on very close objects. Without a visual aid – reading glasses – a person with presbyopia cannot read a message on a mobile phone or the text in a book. Presbyopia is also popularly known as “short arm syndrome”, because to bring things into focus we need to hold them as far away from our eyes as possible, and even the length of our arm is not enough.
Presbyopia can be eliminated permanently by surgery in which an artificial lens is implanted into the eye. The new lens can also correct other refractive errors and at the same time prevents cataract from developing.
The most common eye and vision diseases
The most common eye diseases include cataract, dry eye syndrome, glaucoma, age-related macular degeneration, keratoconus, amblyopia (lazy eye), various retinal diseases and eye inflammation.
Cataract
In most cases, cataract develops as a result of the natural ageing of the lens. A significant degree of lens opacity is found in every second person over the age of 65 and in up to approximately 70% of people over 75. It manifests as clouding of the lens, and the previously clear lens takes on a greyish tint.
Cataract can only be removed surgically, by replacing the clouded lens with a new one. There are several methods of cataract surgery, some of which are covered by health insurance. Cataract surgery is a completely routine procedure and is one of the safest operations of all.
Glaucoma
After cataract, glaucoma is the second most common eye disease causing permanent blindness worldwide. What makes it so insidious is that it can develop for years without symptoms and without limiting the patient in any way. The patient is therefore unaware that they are developing an eye disease that could take away their sight. Regular eye examinations, especially for people over 40, are the best prevention against the late stages of glaucoma.
MUDr. Ivo Ďurkovič, MPH, chief ophthalmologist of the iClinic network, defines glaucoma as “an umbrella term for eye diseases that result in damage to the optic nerve, which transmits visual information from the eyes to the brain.”
The exact cause of glaucoma has not yet been identified; high intraocular pressure is considered the greatest risk factor. Glaucoma cannot be cured completely – doctors can only halt its progression. The later glaucoma is diagnosed, the more difficult the treatment.
Age-related
macular degeneration (AMD)
AMD is a disease of the macula – the central part of the retina. The macula is the area of sharpest vision, and damage to it leads to a loss of central vision. Symptoms may include blurred vision, poorer vision in the dark, gaps in the visual field, distorted images, dark spots in front of the eyes and reduced colour sensitivity.
Here too, regular eye examinations are the most effective prevention, as macular degeneration can develop for years without symptoms, and at the same time this eye disease cannot be cured, only stabilised.
Keratoconus
Keratoconus is a congenital disease of the cornea in which the cornea gradually thins and bulges into a cone shape. It is one of the eye diseases that can develop in the early stages without any visible or noticeable symptoms.
The first symptoms, in the form of deteriorating vision, may appear during adolescence. Keratoconus can also manifest as increasing short-sightedness and astigmatism, double and ghosted vision, difficulty driving or reading, and sensitivity to light (photophobia).
Amblyopia (lazy eye)
Amblyopia is a functional vision disorder that mainly affects children – in Slovakia, approximately 2–3% of children have it. The essence of the condition is that the brain evaluates the images from both eyes, and if the image from one eye is weaker, the brain suppresses it because it considers it incorrect. Put simply, the affected eye “wants to work” less and less, which is why this condition is also known as lazy eye syndrome. The brain ignores the images from that eye more and more often, until it “switches it off” completely. The affected eye therefore does not develop properly, which is particularly dangerous in childhood.
Dry eye syndrome
Dry eye syndrome is one of the most common eye conditions. It is also often regarded as a disease of the third millennium. It is increasingly caused by long hours of computer work, which is typical of developed countries in particular. Dry eye results from insufficient tear production and/or poor tear quality. Only rarely can it lead to irreversible blindness; in the vast majority of cases it affects only quality of life.
Retinal diseases
The retina is a very important part of the eye. It captures the image entering the eye and sends it to the brain via the optic nerve. Several retinal diseases can develop without symptoms, and only an eye examination can detect them at an early stage. The most common retinal diseases include retinal detachment, retinal vascular occlusions, diabetic retinopathy and the age-related macular degeneration mentioned above.
Eye inflammation
Hazy or blurred vision can also be caused by eye inflammation. It is caused by bacteria and viruses that get into the eye, for example via dirty hands. Children and people with allergies are particularly at risk, but eye inflammation can occur in anyone, for example as a result of an eye injury.
