Albinism (from Latin albus, “white”; see extended etymology, also called achromia, achromasia, or achromatosis) is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of an enzyme involved in the production of melanin. Albinism results from inheritance of recessive gene alleles and is known to affect all vertebrates, including humans. The most common term used for an organism affected by albinism is “albino“. Additional clinical adjectives sometimes used to refer to animals are “albinoid” and “albinic”.
Albinism is associated with a number of vision defects, such as photophobia, nystagmus and astigmatism. Lack of skin pigmentation makes the organism more susceptible to sunburn and skin cancers.
Amblyopia (say this: “am-blee-oh-pee-ah”) is an eye problem that causes loss of or poor vision in one or both of a child’s eyes. Amblyopia usually affects only one of the eyes, but sometimes it can affect both. Amblyopia is the most common cause of vision problems in children.
What causes amblyopia?
Anything that happens to blur a child’s vision or cause the eyes to become crossed may cause amblyopia. For example, children who have strabismus(also called “crossed eyes”), cataracts, a droopy eyelid or who need glasses to see better may get amblyopia.
All babies are born with poor eyesight. As babies grow, their eyesight gets better. In order to develop good eyesight, both eyes needs to provide a clear, focused image that is the same in both eyes. If the image isn’t clear in one eye or if the image isn’t the same in both eyes, the child gets a different picture from each eye. The child’s brain naturally tries to fix this problem by blocking out the picture from the weaker eye. If the problem is not fixed when the child is young, the child’s brain will always ignore pictures from the weak eye, causing amblyopia.
How is amblyopia treated?
The treatment for amblyopia depends on what is causing it. After the cause of the amblyopia is found, the child will need to use the weaker eye most of the time, so it will get stronger. To make the child use the weaker eye, a patch can be put over the stronger eye. Sometimes, eye drops or special glasses are used to blur the vision in the stronger eye. This makes the weaker eye become stronger. Patches may be used all day or part of the day, depending on the child’s age and vision.
Glasses or contact lenses fix some problems. Surgery may be needed for cataracts, droopy eyelids or crossed eyes.
Treatment usually lasts until vision is normal, or until vision stops getting better. For most children, this takes several weeks. A few children need to use eye patches until they are 8 years to 10 years of age.
Why is early treatment important?
The first few years of life are the most important for eyesight. After a child is 8 years to 10 years of age, the brain’s vision system is complete. It can’t develop anymore. If the amblyopia hasn’t been treated by this age, the child will have poor vision for life. It won’t be possible to fix it with glasses, patching or any other treatment.
There’s a small chance that using an eye patch for too long can hurt the strong eye. For this reason, children who are wearing eye patches should see their doctor often during the treatment
Anophthalmia, is the congenital absence of one or both eyes.
True or primary anophthalmos is very rare. Only when there is complete absence of the ocular tissue within the orbit can the diagnosis of true anophthalmos be made. Extreme microphthalmos is seen more commonly. In this condition, a very small globe is present within the orbital soft tissue, which is not visible on initial examination.
There are three classifications for this condition:
§ Primary anophthalmia is a complete absence of eye tissue due to a failure of the part of the brain that forms the eye.
§ Secondary anophthalmia the eye starts to develop and for some reason stops, leaving the infant with only residual eye tissue or extremely small eyes which can only be seen under close examination.
§ Degenerative anophthalmia the eye started to form and, for some reason, degenerated. One reason for this occurring could be a lack of blood supply to the eye.
Anophthalmia and microphthalmia may occur secondary to the arrest of development of the eye at various stages of growth of the optic vesicle. It is important to recognize microphthalmia because the development of the orbital region, as well as the lids and fornices, is dependent upon the presence of a normal-sized eye in utero. Anophthalmia is sometimes a clinical characteristic of Trisomy 13 (Patau syndrome) which is a Gross Chromosomal Abnormality.
Early treatment with various expanders or surgery, when necessary, will help decrease the orbital asymmetry and cosmetic deformities in these children.
Aniridia is the absence of the iris. This usually occurs in both eyes. It can be congenital or caused by a penetrant injury. Congenital aniridia is not just an isolated defect in iris development but is a panocular disorder with macular and optic nerve hypoplasia, cataract, andcorneal changes. Vision is severely compromised with the aniridia and the disorder is frequently associated with a number of complications with the eye: nystagmus, amblyopia, buphthalmos, and cataract.