Microphthalmia and anophthalmia: what genetic syndrome causes small eyes?

Optically reviewed by Khuram Sarwar, Dispensing Optician at Feel Good Contacts.

Microphthalmia and anophthalmia are the names of two conditions that are the result of partial or no eye development at birth. Some babies can be born without fully formed eyes, or without one eye or both eyes entirely.

People are born in all shapes, sizes and with different abilities. Because growing a human being is an incredibly complex thing to do, during pregnancy some parts of the body can be formed differently, which results in life-long lifestyle differences. Eyes are no exception, so microphthalmia, anophthalmia and other eye abnormalities can occur at birth.

What is the difference between microphthalmia and anophthalmia?

Anophthalmia is the name given to the condition where babies are born without eyes. This eye disorder can be unilateral, meaning that one eye is missing, or it can be a bilateral condition, where both eyes are missing.

Microphthalmia is a similar condition that affects eye development before birth, but with microphthalmia the eyes are formed in a disorganised manner or are too small to function normally. Like anophthalmia, microphthalmia can occur unilaterally or bilaterally.

A person can have both of these eye conditions at the same time. Frequently, microphthalmia and anophthalmia are present among other related symptoms or as part of a congenital syndrome (displaying a common group of symptoms simultaneously) as well, including:

• Aicardi syndrome: A rare disorder wherein one or more body parts are missing at birth. Developmental difficulties such as learning difficulties and seizures are common.
• CHARGE syndrome: A complex group of disabilities affecting, but not limited to, six common areas of the body; coloboma, heart defects, atresia choanae (nasal passage), retardation (developmental delays), genital abnormalities and ear abnormalities.
• SOX2 anophthalmia syndrome : Used synonymously with the term ‘severe microphthalmia’ with the addition of brain seizures and developmental delays.
• Lenz microphthalmia syndrome: A form of severe microphthalmia including abnormal development of one or more other body parts and additional eye symptoms, such as clouding of the lens (cataracts), uncontrolled eye movements (nystagmus), coloboma and/or glaucoma. Common body abnormalities include ears, teeth, hands, skeleton, urinary system, brain and heart.

Is microphthalmia a disability?

Sometimes referred to as ‘small eye syndrome’ or ‘microphthalmos’, microphthalmia can result in vision loss, but severity will vary. It can cause substantial visual impairment, which requires specialist treatment, and blindness is common.

People with microphthalmia or small eye syndrome may also have a condition called coloboma, characterised by a gap or split in the structures that make up the eye.

What causes microphthalmia and anophthalmia?

Since both of these types of eye abnormalities occur before birth, it is especially difficult to determine any causal relationships that lead to the development of anophthalmia or microphthalmia.

In cases, small eye syndrome can exhibit a hereditary pattern. Some theories suggest that environmental factors during pregnancy can result in conditions present at birth. Suspected factors range from mothers experiencing nutrient deficiencies during pregnancy to exposure to certain chemicals, radiation or diseases during gestation.

Are microphthalmia and anophthalmia preventable?

At current, it is unknown whether anophthalmia and microphthalmia can be prevented. However, it is possible to detect the condition early on. Small eye syndrome (microphthalmia) and anophthalmia can be diagnosed during pregnancy or after birth.

During pregnancy, doctors can identify anophthalmia and microphthalmia at around 11-12 weeks using scanning technology such as ultrasound. The technology picks up on foetal orbits which indicate concurrent syndromic findings. While these findings can be largely subjective, they give more acute data than genetic testing, which is another method of early identification of small eye syndrome.

How common is microphthalmia and anophthalmia?

Anophthalmia and microphthalmia are extremely rare conditions and only affect a very small number of children. In fact, MACS (Microphthalmia, Anophthalmia & Coloboma Support) estimates that around 90 children in the UK are born with these types of eye conditions every year.

In 2023, figures suggest that microphthalmia, anophthalmia and coloboma eye disorder diagnoses can be placed at just over 0.01% of children born in the UK each year.

Do microphthalmia eyes grow?

No, microphthalmia is a permanent eye disorder. People born with small eye syndrome or with anophthalmia (no eye) in one or both eyes will have that condition for life.

Sight can’t be restored, but children with this condition may benefit from artificial eyes to help with appearance. The condition must also be managed during childhood development to reduce further complications.

How do you treat microphthalmia?

Eye sockets need to have the right structural support for a baby’s facial and brain growth and development. As a result of anophthalmia or microphthalmia, the bones that shape the eye socket may be underdeveloped.

Devices called conformers can be fitted into a baby’s eye socket to maintain the structural integrity of the cranium and face during the early years of development. As babies get older, these devices will need to be adjusted according to the expected rate of growth.

A team of eye specialists should frequently monitor children with these eye disorders early in life. When conditions such as cataracts or detached retina arise, and those conditions are severe, surgery is usually the recommended course of action.

Aside from addressing preventable medical complications, there are also methods to help with the cosmetic impact of underdevelopment in the eyes.

Children who suffer from anophthalmia or very severe microphthalmia can be fitted for an artificial eye. For milder cases of microphthalmia where a significant amount of vision remains, glasses or contacts can help to improve eyesight.