Small Eye Openings (Short Palpebral Fissures)

What palpebral fissures are

The palpebral fissure is the opening between the upper and lower eyelids. Its length is measured horizontally from the inner corner (where the lids meet near the nose) to the outer corner. It grows quickly in infancy and more slowly through childhood.

A fissure is called short when it measures at or below the 10th percentile for age on standard charts. Doctors use a small ruler held close to the eye, or photo-based measuring tools, because judging by eye alone is unreliable. Features that can make eyes look small but are not short fissures include:

• Epicanthal folds: skin folds at the inner corner that hide part of the eye, common in many ethnic groups and in babies
• Ptosis: a drooping upper lid that narrows the opening vertically
• Wide-set eyes or a broad nasal bridge
• Puffy eyelids in newborns

Causes of short palpebral fissures

Fetal alcohol spectrum disorders

Alcohol exposure in pregnancy, especially in the first trimester when the face is forming, can cause a characteristic set of features. Fetal alcohol syndrome (FAS) is diagnosed when a child has:

• at least 2 of the 3 facial features: short palpebral fissures, a smooth philtrum, and a thin upper lip
• growth deficiency (height or weight at or below the 10th percentile)
• signs of brain involvement, such as a small head, structural brain differences, or difficulties with learning, memory, attention or behavior

Children with fewer features may be diagnosed with partial FAS or another fetal alcohol spectrum disorder. There is no known safe amount of alcohol in pregnancy. See fetal alcohol syndrome.

Genetic and chromosomal conditions

Short or narrow eye openings occur in several syndromes, including:

• 22q11.2 deletion syndrome: hooded eyelids and narrow eye openings with heart defects and palate problems
• Williams syndrome: with puffiness around the eyes and a friendly personality
• Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES): narrow eye openings, droopy lids and an upside-down epicanthal fold
• Down syndrome: upslanting eye openings with epicanthal folds, sometimes appearing small
• Other conditions such as Dubowitz syndrome and some forms of microcephaly

Normal variation

Eye shape and size vary by family and ancestry. A child who resembles a parent and has no other unusual features, normal growth and normal development is very likely to be healthy.

How doctors assess small eye openings

A pediatrician or clinical geneticist will:

1. Measure the palpebral fissure length and compare it with age-specific charts.
2. Examine other facial features, including the philtrum and upper lip using a lip-philtrum guide, and head circumference.
3. Check growth against growth charts.
4. Review development, learning and behavior, sometimes with formal testing.
5. Take a pregnancy history, including alcohol and medicine exposure, asked in a non-judgmental way.
6. Look for other findings, such as heart murmurs, hearing or vision problems, or joint and limb differences.
7. Arrange genetic testing (chromosomal microarray or specific gene tests) if a syndrome is suspected.
8. Refer to an eye specialist if eyelids droop or vision may be affected.

Treatment and support

The eye openings themselves usually need no treatment. Care focuses on the underlying cause:

• Fetal alcohol spectrum disorders: early intervention, speech, occupational and behavioral therapy, educational support and parent training. Early diagnosis is linked with better outcomes.
• Genetic syndromes: management of associated problems such as heart defects, hearing loss or learning needs by a team of specialists.
• Drooping eyelids: surgery may be needed if the lids block vision, to prevent lazy eye (amblyopia).
• Regular vision checks for any child with eyelid differences.

Frequently asked questions

What are short palpebral fissures?

They are eye openings that are shorter than normal from the inner to the outer corner, measured against age-based charts. They can be a normal family trait or part of conditions such as fetal alcohol syndrome or some genetic syndromes.

Do small eye openings always mean fetal alcohol syndrome?

No. Short eye openings on their own are not enough to diagnose FAS. The diagnosis needs at least two of the three facial features, plus growth problems and evidence of brain involvement, together with a careful history.

How are palpebral fissures measured?

A clinician measures the distance between the inner and outer corners of each eye with a small ruler or from a standardized photo, then compares it with growth charts for the child's age. At or below the 10th percentile is considered short.

Can small eye openings affect vision?

Short fissures alone do not usually affect vision. Drooping eyelids that cover the pupil, or other eye conditions linked with some syndromes, can affect vision development, so regular eye checks are recommended.