Human eye cross-sectional view grayscale

Macular hypoplasia (or foveal hypoplasia) is a rare medical condition involving the underdevelopment of the

macula The macula (/ˈmakjʊlə/) or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal avas ...

, a small area on the

retina The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...

(the eye's internal surface) responsible for seeing in detail and sensing light. Macular hypoplasia is often associated with

albinism Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and reddish pink or blue eyes. Individuals with the condition are referred to as albinos. Varied use and interpretation of ...

. When the foveal area of the eye is compromised, visual clarity and color perception are reduced. Diagnosing is done by an

ophthalmologist Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a ...

. The foveal area of the eye is located in the back of the eyeball. It is placed in front of the optic nerve and is responsible for light sensory and visual perceptiveness. Other diseases with foveal hypoplasia besides

include

aniridia Aniridia is a condition characterized by the absence or near absence of the iris, the colored, muscular ring in the eye that controls the size of the pupil and regulates the amount of light entering the eye. This absence results in a primarily b ...

, retinopathy of prematurity, and

Alport syndrome Alport syndrome is a genetic disorder affecting around 1 in 5,000–10,000 children, characterized by glomerulonephritis, end-stage kidney disease, and hearing loss. Alport syndrome can also affect the eyes, though the changes do not usually affec ...

Causes

Macular hypoplasia occurs the most in people that have a diagnosis of

. There are four gene mutations that occur in albinism and are linked to macular hypoplasia. The four mutations can occur on the phenotypes of FH, PAX6, SLC38A8, and AHR. The most common gene mutation is the FH phenotype and has a 67.5% correlation rate to macular hypoplasia. The disorder can occur through two distinct genetic abnormalities. The difference among mutated genes results in a difference in phenotypic display of macular hypoplasia. In phenotype FVH1, there is a

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, ...

of the PAX6 gene. FVH1 occurs through

autosomal dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the Phenotype, effect of a different variant of the same gene on Homologous chromosome, the other copy of the chromosome. The firs ...

inheritance. The mutation is passed down to the recipient from the

mother A mother is the female parent of a child. A woman may be considered a mother by virtue of having given birth, by raising a child who may or may not be her biological offspring, or by supplying her ovum for fertilisation in the case of ges ...

father A father is the male parent of a child. Besides the paternal bonds of a father to his children, the father may have a parental, legal, and social relationship with the child that carries with it certain rights and obligations. A biological fat ...

. FVH1 type of macular hypoplasia coincides with

cataracts A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or double vision, halos around ligh ...

in the eyes. In phenotype, FVH1 is caused by a SLC38A8 gene mutation. FVH2 occurs by autosomal recessive inheritance. Both parents pass the mutated gene to the child. Macular hypoplasia prevails due to improper placement of the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...

Diagnosis

A lack of foveal

pigmentation A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly insoluble and chemically unreactive in water or another medium; in contrast, dyes are colored substances which are soluble or go in ...

or circumfoveal light

reflex In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs ...

is a common finding of macular hypoplasia; however, diagnosis is challenging for those that have a darker pigmentation of the skin, hair, and iris. Originally, findings of

nystagmus Nystagmus is a condition of involuntary (or voluntary, in some cases) Eye movement (sensory), eye movement. People can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in visual impairment, re ...

, or involuntary movement, and lack of blood flow to the retina using

fluorescein angiography Fluorescein angiography (FA), fluorescent angiography (FAG), or fundus fluorescein angiography (FFA) is a technique for examining the circulation of the retina and choroid (parts of the fundus) using a fluorescent dye and a specialized camera. ...

(FA) were used to detect macular hypoplasia. FA uses light to look at the retina and blood vessel development in the eye using a dye. Today, a newer technology,

optical coherence tomography Optical coherence tomography (OCT) is a high-resolution imaging technique with most of its applications in medicine and biology. OCT uses coherent near-infrared light to obtain micrometer-level depth resolved images of biological tissue or oth ...

(OCT) is used to detect foveal hypoplasia and does not require a dye. OCT allows professionals to see the structures in the eye, usually the thickness of the

and

. This is a noninvasive procedure where patients rest their chin and focus on a green light within the machine. Eye dryness and fatigue are the limited risks associated with this scan. Other diseases that can be diagnosed using OCT are

glaucoma Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of ...

macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred vision, blurred or vision loss, no vision in the center of the visual field. Early on there are often no sym ...

, and diabetes-related

retinopathy Retinopathy is any damage to the retina of the eyes, which may cause vision impairment. Retinopathy often refers to retinal vascular disease, or damage to the retina caused by abnormal blood flow. Age-related macular degeneration is technically in ...

Treatment

Currently, there is no specific

pharmacotherapy Pharmacotherapy, also known as pharmacological therapy or drug therapy, is defined as medical treatment that utilizes one or more pharmaceutical drugs to improve ongoing symptoms (symptomatic relief), treat the underlying condition, or act as a p ...

that prevents or reserves macular hypoplasia; however,

reading glasses A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are w ...

or other vision devices can be used to enhance the quality of life for individuals.

References

External links

{{Medical resources , ICD10 = H26.0 , ICD9 = , ICDO = , OMIM = 136520 , DiseasesDB = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , MeSH = , GeneReviewsNBK = , GeneReviewsName = , Orphanet = 2253 Eye diseases Rare diseases