Amblyopia (Greek : “dull eye”) or amblyopia is a functional disorder of the sense of form or place. It is due to inadequate development of the visual system in early childhood and, as a result, leads to reduced visual acuity (visual loss) throughout life. Amblyopia is therefore a form of amblyopia with reduced visual acuity. Only one in three children with amblyopia and only one in ten with strabismus is detected during the pediatric screening. For this reason, additional early detection is recommended. The so-called amblyopia screening, carried out by your ophthalmologist, is a sensible individual health service. In northern Germany, the prevalence (frequency of a disease in the population over a period of time) for amblyopia (developmental amblyopia) in 6-year-olds is 5-6%. Amblyopia can lead to poor vision and even blindness. Overall, unilateral amblyopia is more likely to cause vision loss in the healthy eye than in the strabismic eye over time. The prevalence of amblyopia in Germany is reported to be 5.6%. In 49 % of the amblyopic subjects anisometropia (different refraction/refractive power of both eyes) was found, in 23 % strabismus (strabismus), in 17 % strabismus and anisometropia and in 2 % deprivation (in which the optical axis is displaced for example by a congenital upper eyelid ptosis (drooping upper eyelid) or a cataract). In three subjects (2%), a traumatic cataract (in preschool age) was the cause of relative amblyopia. 7% of the amblyopes were binocular (both eyes). The leading symptom of amblyopia is a decrease in visual acuity. It is a consequence of stimulus deprivation as well as of pathological binocular interaction (disturbance of the cooperation of the double eye, e.g. strabismus). Amblyopia usually develops during the early sensitive phase of visual development, in the first 3-4 months of life, making effective early detection all the more important. However, amblyopia (amblyopia) can also develop in later years with later onset of strabismus. It is therefore important to continuously check the development of vision in children at individually determined intervals. Note: Even unilateral amblyopia leads to at least a doubled risk of bilateral visual loss (loss of visual acuity). Amblyopia is usually not visible in children, especially if there is no strabismus but anisometropia (unequal refraction/refractive power of both eyes). The behavior of the children is conspicuous only in case of pronounced visual impairment. Then, however, treatment is all the more urgent.
Risk factors
Hereditary risk factors: risk of heredity (inheritance) for strabismus (strabismus)/amblyopia.
- 20% if one parent is strabismus and hyperopia (farsightedness) in the child: > 3dpt)
- 50% if both parents squint and child’s hyperopia: > 3dpt)
- 10% if both parents squint and low hyperopia of the child up to 1.5 dpt
Main risk factors
- Strabismus (squint)
- Anisometropia (unequal refraction/refractive power of both eyes).
- Ametropia (defective vision due to a refractive error).
- Eyelid anomalies / opacities of the refractive media.
- Lacrimal stenosis (obstruction of the lacrimal ducts).
- Premature birth
- Perinatal complications (complications between the 24th week of pregnancy and the 7th day of life after birth).
- Family stress
Diagnostics
If repeated measurements confirm a difference in visual acuity of both eyes of two or more lines on the visual chart and any refractive errors (refractive errors) have been compensated for by corrective lenses, and no other interfering factors of visual function are present, unilateral amblyopia is present.Refractive errors are present in more than two-thirds of all amblyopia. Notice:
- Use closely spaced visual signs when testing visual acuity.
- Visual acuity determination is reliable from the age of about 4 years.
Only in very rare cases is bilateral amblyopia present. This may be due to a high, but relatively symmetrical refractive error.
Screening
Early detection: timing of screening examinations.
- In the 1st week of life, for eyelid abnormalities (e.g., narrowing of the palpebral fissure) and media opacity (e.g.B. Opacity of the vitreous body of the eyes and thus impairing the incidence of light).
- Between 6 and 8 weeks, useful in all children.
- At 6-12 months, to exclude strabismus and refractive anomalies.
- At the age of 3-4 years, as here is already a visual acuity test possible.
Note: Vision development is particularly susceptible to interference in the first months of life. Severity of amblyopia
| Visual acuity at the amblyopic eye | |
| Highly | < 0,1 |
| Medium | ≤ 3 |
| Light | ≤ 8 |
Procedures or methods
- Brückner test – transillumination test according to BrücknerThe Brückner test consists of inspection of the eye in transmitted light. If the eye is cross-eyed, even with a small angular deviation of one eye, the color in the transmitted light will be different than on the opposite side, this effect is well observed, for example, red eyes on flash photos.
- Pupillomotor and oculomotor checkCheck the pupillary reflex when the light conditions change and check the mobility of the eyes.
- Skiascopic measurementDetermination of refraction, that is, the refractive power of the eye.
- Fixation test on the fundusWith the aid of an electric ophthalmoscope, a small object, e.g. a star figure, is projected onto the back of the eye (fundus). It is now checked whether the patient can fixate the star centrally at the fundus with the eye and follow it after a shift. External (non-central) fixation may be strabismus (strabismus).
- Morphological overviewGeneral overview of the condition of the eye.
- Visual acuity determinationDetermination of visual acuity with age-appropriate visual signs and additional testing with narrow-vision signs, which are particularly suitable for the diagnosis of ambylopia.
Therapy
Therapy goals [S2e guideline]:
- Achievement of the best possible individual vision.
- Improvement of binocular vision (binocular).
- Reduction of the risk of blindness of the non-amblyopic partner eye.
Therapy recommendations
- Full or partial occlusion (masking of the guide eye with, for example, a child-friendly plaster).
- Penalization (lowering the visual acuity of the better eye by a special lens and / or eye drops).
- Atropinization (accommodation paralysis of the healthy eye by atropine drops).
- Removal of visual obstacles, such as cataract (cataract).
- Correction of refractive anomalies (refractive errors) with glasses or contact lenses.
Note: Amblyopia therapy should begin as early as possible, as the prognosis is then very good. Starting treatment before the end of the seventh year of life leads to a significantly higher increase in visual acuity (up to an average of four visual acuity levels) than therapy started after (up to an average of two visual acuity levels).
Benefits
With the above preventive measures, it is now possible to prevent long-term disability or even loss of eyesight or vision. Ensuring the ability of the eyes to read, and thus the ability to cope with education and occupation, is one of the main concerns of early amblyopia detection.
