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 (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

(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 pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the term ...

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

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

. 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 the absence of the iris, a muscular structure that opens and closes the pupil to allow light into the eye. It is also responsible for eye color. Without it, the central eye appears all black. It can be congenital, in which both eye ...

, 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 affect v ...

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 A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...

. 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, mi ...

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 effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

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 childbirth, birth, by raising a child who may or may not be her biological offspring, or by supplying her ovum for fertilisation in the cas ...

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. An adoptive fathe ...

. 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. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble w ...

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 colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

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. Infants can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision. Due to the invol ...

, 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. S ...

(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 an imaging technique that uses low-coherence light to capture micrometer-resolution, two- and three-dimensional images from within optical scattering media (e.g., biological tissue). It is used for medical ...

(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 result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

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

, 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 inc ...

Treatment

Currently, there is no specific

pharmacotherapy Pharmacotherapy is therapy using pharmaceutical drugs, as distinguished from therapy using surgery (surgical therapy), radiation (radiation therapy), movement ( physical therapy), or other modes. Among physicians, sometimes the term ''medical the ...

that prevents or reserves macular hypoplasia; however,

reading glasses A corrective lens is a lens (i.e. a transmissive optical device) that is typically worn in front of the eye to improve daily vision. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasse ...

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

References

External links

Eye diseases Rare diseases {{eye-disease-stub