The lazy eye

What is it?

The lazy eye or amblyopia is a decrease in visual acuity in one or both eyes, without there being a cause that justifies it.

Why does it happen?

It occurs when the visual signals that reach the brain are better (sharper) by one eye than by another. The brain then prefers to connect (establish synapses) with the eye that provides the best vision, leaving the other eye with fewer "connections" which implies a worse visual development.

The causes can be diverse: anisometropias (different graduation of one eye with respect to another), strabismus (ocular misalignment), cataracts, ptosis (drooping eyelid), retinopathies ....

Visual development begins at birth and ends approximately between 8-9 years.

Being a brain problem, the smaller the child, more plasticity (ability to change) and ease to reverse amblyopia.

When to treat it?

Classically, it is established that amblyopia can be recovered until the age of 8-9, which is the period of greatest cerebral plasticity. Although there are cases that can be recovered at later ages, it is very difficult and the results are not as satisfactory as if you detect them at an early age, ideally less than 4-5 years old.

When to treat it?

The best treatment is prevention by doing an early checkup between 3-4 years or earlier if parents notice "something weird" in the view.
To solve the amblyopia, you must first solve the problem that causes it (put on glasses, operate the cataract, eyelid surgery...), and then carry out penalization measures (patches, etc.) on the healthy eye so that the connections of one and another in the brain.

The correct graduation, occlusions and penalties are the best treatment that has been demonstrated for amblyopia. Visual therapy could also help, although more studies are needed to corroborate it.

Refraction (glasses)

A correct graduation (glasses) is essential to be able to treat amblyopia.

In mild-moderate anisometropia (different graduation from one eye to another) it is usually enough to correct amblyopia, and does not need further treatment.

In cases where there is associated strabismus, it is necessary to prescribe the complete refraction verified under cycloplegia to eliminate the accommodative factor of strabismus

Occlusions (patches)

The most used technique is the occlusion of the "good eye".

The number of hours/day has been decreasing with time and experience, from the occlusions of the whole day for several days in a row, to the occlusions only a few hours a day that we use today (in some exceptional cases whole day is still occluded). The number of hours will depend on the age of the patient and the severity of the case.

I do checkups every 2-4 months if they are hourly occlusions and every 2-3 weeks if they are total.

Here I show you my occlusion pattern (keep in mind that this is an approximate guideline, but there are always exceptions).

VA Diff \ Age

< 4 y

4 a 6 y

6 a 8 y

> 8 y

0,1 – 0,2

1 o 2 h/day

2 h/day

3-4 h/day

4 o 6 h/day

0,3 – 0,5

2 h/day

3-4 h/day

6 h/day

6 h/day

0,6 – 0,7

3-4 h/day

6 h/day

6 h/day

* Total 6/1

0,8 – 0,9

6 h/day

6 h/day

* Total 6/1

* Total 6/1

 

  • Dif. AV: Visual acuity difference in decimal system 0.1 to 1.
  • Total 6/1= 6 consecutive days and 1 rest.

* With total occlusions, care must be taken if there is no strabismus, because a latent strabismus could be decompensated. That is why I only prescribe them if there is failure of the hourly occlusion or if there was a clear strabismus before.

Penalties with glasses and/or drops

In anisometropia and microtropia it can be useful to penalize the healthy eye:

  • Drops that do not allow you to focus closely (atropine, cycloplegic ...).
  • Adding plus lenses (creating a myopia) so that you do not see well from afar, making that for far prefer to use the bad instead of the good.
  • Combining both techniques
Visual therapy and others

Visual therapy, methods with the iPad and tablets. None of these methods has proven more effective than the previous methods and the level of evidence from the studies is not the best either. Although they can serve as help and maintenance.

We will have to wait for better studies to see its real effect.

 

Other links with information about amblyopia and its treatment:

Review of the Spanish Society of Ophthalmology (SEDOP) of November 2016: "TREATMENT OF AMBLIOPIA BASED ON SCIENTIFIC EVIDENCE" in spanish.

Amblyopia (AAPOS) in english.

Dr. Caballero P...