What is visual impairment (amblyopia)?
Is a monocular (rarely binocular) decrease in visual acuity, despite optimal correction and in the absence of pathological changes in the eyeball and visual pathway.
What are the causes of visual impairment?
Visual impairment caused by strabismus
It can develop in a deviated eye in a strabismic patient due to long-term suppression. Impressions from the guiding (non-strabismic) eye dominate over those from the strabismic eye, and this is the reason for the development of visual impairment.
Visual impairment caused by refractive error
It can arise from uncorrected differential vision or astigmatism. If one eye is more hyperopic than the other, it will never see a sharp image, because the eye with the smaller defect needs less accommodation at any distance. Accommodative refers to the ability of the eye lens to change its power. Consequently, a more hyperopic eye with constant suppression will develop a visual impairment, which means that the image emerging from that eye does not fully reach our brain.
The reason for the visual impairment may be uncorrected astigmatism. The child may develop visual impairment in both eyes due to lack of exposure to the ideal retinal image. This type of visual impairment is generally minor, and vision improves after the use of cylindrical glasses in the early school years.
Visual impairment caused by a lack of visual stimuli, e.g. congenital cataracts, congenital drooping of the upper eyelid or covering the eye for too long - we then speak of "visual impairment from disuse."
Does laser vision correction eliminate vision loss?
Laser vision correction is designed to correct a refractive error (defect in vision), which can be one of the causes of visual impairment, while the visual impairment itself will not disappear. Yet, a patient achieving a given visual acuity in the best correction after vision correction will see the same or even better already without the use of glasses or contact lenses.
Why can the patient see better?
Improved vision mainly affects myopic people who get a diminished image in spectacle correction, which is eliminated with laser vision correction, and the image becomes actual size.
Why get laser vision correction even if you are visually impaired?
First of all, it is the best alternative to get rid of glasses or contact lenses. Besides, the removal of the vision defect causes the visually impaired eye to get rid of the cause of its visual impairment, so with proper exercises there is a chance to improve vision. The most popular exercise is to cover the dominant "better" eye and look with the visually impaired eye, for example, when watching TV. Over time, there may be an improvement in vision in this "worse" eye, as the brain will once again "learn" to perceive a sharp image.