What's the complete definition of Amblyopia?

[Francine]

What's the complete definition of Amblyopia? I've read a number of them, and I was given to understand that a person can develop this later on in life under certain conditions, in addition to its being congenital.

The following would seem to suggest that I'm correct about this:
http://www.indiana.edu/~v755/glossary.htm#Amex

Needless to say, I'm having a debate about this with someone...

Cheers,
Francine

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[Andrew_Doan]

Francine,

Amblyopia is vision loss secondary to visual deprivation BEFORE the visual system fully develops. Thus, this disorder is typically acquired during childhood when the visual system is still young.

The definition from Indiana.edu is correct:

Amblyopia ex anopsia, synonymous with form deprivation amblyopia, is secondary to conditions that prevent light from entering the eye. These may include congenital ptosis, corneal opacity, or cataract. This term has also been used to describe amblyopia secondary to suppression, like that resulting from strabismus, anisometropia, or other amblyopiogenic refractive errors.

I think your assumption that you can develop this later in life stems from the point that this disorder may develop from corneal opacities and cataracts. All the disorders mentioned above occur in children and in babies, e.g. PHPV, congenital glaucoma causing corneal edema/opacity, congential cataracts, strabismus, anisometropia, etc...

Once the visual system has fully matured, it would be very unlikely to see amblyopia. For instance, we see adults who are no light perception from mature white cataracts for years or decades. After removal, they have good visual potential. However, whether or not the neuronal connections to the occipital cortex degrade with time is not clear.

 

[Francine]

>Once the visual system has fully matured, it would be very unlikely to see >amblyopia.
>
> However, whether or not the neuronal connections to the >occipital cortex >degrade with time is not clear.

Good that you mentioned this. Yeah, this is what I was wondering. Who knows what the answer is? Are neuronal connections checked? Is there even a way to do this, as with reflex reactions, etc., or in this case do assumptions have to be made...?

I am guessing that by convention, an adult condition that presents similar to that of a child's amblyopia would be diagnosed as something else, like suppression, etc.

Francine

 

[Andrew_Doan]

Originally posted by Francine
>Once the visual system has fully matured, it would be very unlikely to see >amblyopia.
>
> However, whether or not the neuronal connections to the >occipital cortex >degrade with time is not clear.

Good that you mentioned this. Yeah, this is what I was wondering. Who knows what the answer is? Are neuronal connections checked? Is there even a way to do this, as with reflex reactions, etc., or in this case do assumptions have to be made...?

I am guessing that by convention, an adult condition that presents similar to that of a child's amblyopia would be diagnosed as something else, like suppression, etc.

Francine

Or optic atrophy.

 

[Francine]

Hi MudPhud (I'm impressed, BTW)...

Hmmm...optic atrophy. Meaning a degradation of the whole visual system, including the visual cortex?

What is your personal opinion...are they splitting hairs in not including adult vision conditions as being under the header, "amblyopia" unless they developed in childhood?

Fran

 

[Andrew_Doan]

Originally posted by Francine
Hi MudPhud (I'm impressed, BTW)...

Hmmm...optic atrophy. Meaning a degradation of the whole visual system, including the visual cortex?

What is your personal opinion...are they splitting hairs in not including adult vision conditions as being under the header, "amblyopia" unless they developed in childhood?

Fran

Hi Fran,

I think the term amblyopia is specific for a visual disorder that develops because there was deprivation of visual stimuli, which by definition occurs during childhood when the visual system is still "learning to see". When visual loss occurs in adulthood, it's usually secondary to a pathologic mechanism that is unlike the process observed with amblyopia. Optic atrophy can occur due to trauma, tumors, vascular occlusion/insufficiency, etc... We're not splitting hairs here because visual loss in adults often occurs because of a specific pathologic entity different than the visual deprivation observed in amblyopia.

 

[Richard_Hom]

Dear Francine,

It is unlikely that an adult can "develop" amblyopia in adulthood although it is also likely that an adult may not have been previously diagnosed.

The diagnosis of amblyopia in an adult is always one of "exclusion". I believe that the current notion is that an organic causation is most often the culprit for "adult amblyopia".

A diagnosis of amblyopia in an adult would normally require the following:

1. A refractive imbalance between the eyes called anisometropia or a refractive error of significant degree called hyperopia.

2 A muscle alignment problem such as esotropia where the "guiding" eye "takes over" and the deviating eye is "suppressed" or has anomalous correspondence to avoid diplopia.

3. A history of a high fever or occlusion of either eye during the "plastic" period of the visual system

As you can see, these signs leaves much room for the investigation of an organic cause of any kind of decreased vision in an adult.

Regards,

Originally posted by Francine
What's the complete definition of Amblyopia?

Cheers,
Francine