The Case of the Lazy Eye

Amblyopia or “lazy eye” is a disorder of the visual system characterized poor vision in an eye that is otherwise normal in structure. This condition often occurs during early childhood and results from poor stimulation from the eye to the brain. This visual stimulation is required to reinforce the visual centres in the brain to allow the brain to pay attention to the signals being received.  The two main causes of the poor stimulation are a strabismus (turned eye) and anisometropia  (unequal refractive errors). 

In the case of a strabismus the amblyopia is caused by the brain suppressing the image from the turned eye (otherwise double vision occurs). In the case of anisometropia the brain ignores the blurry or poorly corrected eye and only pays attention to the good eye. It is this latter case that is often the most surprising to parents when amblyopia is detected in the early childhood years by an eye care professional. There exists a “plastic period” where those reinforcements loops from the eye to the brain are formed. This plastic period exists from birth until about the age of 8 or 9 which is where the window of treatment exists.

The goal of treatment is to break the amblyopia by providing the brain with a clear image from each eye.  Let’s use a real life example. Eric was three years old when I first examined him. He could see perfectly all of the animals from the Children’s Allen chart in his right eye but he could not see anything from his left eye. His mother suspected that he was kidding with us but after I refracted him to plano in the right eye and +6.00 in the left eye. I assured his mother that Eric was not joking around. The corrected visual acuity in the left eye was 20/60, still quite a bit weaker than the plano right eye. We decided to fit Eric with an continuous wear silicone hydrogel contact lens in his left eye only. We instituted a patching regimen of the right eye for several hours per day in order to facilitate the proper feedback loop for the lazy left eye. Today Eric is 12 years old and is best corrected to 20/25+ in the left eye. He is still wearing a continuous wear contact lens with great results. Eric’s parents were an integral part of the successful rehabilitation of Eric’s lazy eye. Diligence with patching is critical to the long term success of this therapy.

Alternatives to Patching

Some practitioners have started using atropine eye drops to treat amblyopia instead of an eye patch. Atropine blurs the good eye and forces the child to use the amblyopic eye and thereby strengthen it.

Research is ongoing into improving vision in older amblyopic patients. It appears that long standing amblyopia can be improved by computer programs that stimulate neural changes leading to improvements in visual acuity and contrast sensitivity.

Acupuncture may eventually become another optional treatment apart from patching for lazy eye, especially among older children who have a poorer response to patching, say researchers from China in Archives of Ophthalmology. More studies are required but initial results are positive.

Detection is Key

The biggest take home message is that all children should have a full eye health examination by the age of three and every year afterwards. It is critical to promote routine eye examinations to all of your clients and by doing so you may be helping a lazy eye to see again.