Monolids (Epicanthal Folds) and Their Causes (2024)

Eye Health

ByKelly Burch

Updated on August 01, 2024

Medically reviewed byChristine L. Larsen, MD

Fact checked byNick Blackmer

“Monolids” is a common term for epicanthal folds, a type of eyelid seen in people who don't have a double eyelid or crease. Monolids typically occur in some people of Asian ethnicity, with eyelids shaped by a skin fold at the inner eye (the canthus) that can create a more narrowed appearance.

Monolids are normal and do not affect vision on their own, although cosmetic surgery to create a double eyelid (sometimes called Asian blepharoplasty) is popular. In some cases, a monolid is linked to a genetic condition like Down syndrome or an age-related, acquired eyelid droop called ptosis.

Monolids (Epicanthal Folds) and Their Causes (1)

Asian Ethnicity

A double lid gives the upper eyelid the appearance of having two sections due to a visible crease. About 50% of people of Asian descent have a fold at the canthus that creates a monolid. The number, however, varies among specific populations.

Some studies have found higher levels among Koreans than the Japanese. Other researchers find lower rates of monolids among Malays than ethnic Chinese people who live together in Malaysia, even though they share Mongoloid roots.

The epicanthal fold is caused by a genetic variation and not all Asian people have them.

Medical Conditions

Monolids may affect non-Asian people. However, it’s rare and is most specifically related to genetic and developmental disorders. These medical conditions can include:

  • Down syndrome: Monolids and other physical characteristics often occur with Down syndrome, a genetic disorder also called trisomy 21. Medical conditions such as heart conditions or intellectual and developmental disabilities are common.
  • Fetal alcohol syndrome: The effects of alcohol exposure on the developing fetus can include a wide range of medical problems and mental disabilities. It can also cause facial and physical abnormalities, including monolids.
  • Turner syndrome: Features of Turner syndrome can include short stature and monolids. This genetic condition affects females who do not have a complete pair of chromosomes in some or all of their body cells.
  • Blepharophimosis: Monolids, with narrow eyes, skin in the lower eyelids, and widely set eyes, are common along with other facial changes in this rare developmental disorder, also called BPES.
  • Williams syndrome: This genetic disordercan cause developmental delays, heart problems, low muscle tone, and attention disorders. People with Williams syndrome also tend to have unique facial traits that include epicanthal folds.
  • Noonan syndrome: A rare genetic disorder that can cause a person's eyes to slant downward and appear to wrap around the sides of the face. Monolids are common, along with other impacts.
  • Zellweger syndrome: This rare metabolic disorder is inherited and affects almost all cells in the body. The syndrome can lead to atypical facial structures that include epicanthal folds.
  • Phenylketonuria (PKU): This is an inherited metabolic disorder that requires people with PKU to follow a special diet due to problems in how the body breaks down a certain amino acid. Those born with PKU may have monolids or other identifiable physical characteristics.

Other medical conditions that can lead to a monolid appearance often affect older adults. They include:

  • Ptosis: Ptosis refers to a condition in which the upper eyelids droop over the eye. It may be congenital (present at birth) or it might come about due to injury or aging.
  • Hooded eyes: Known as dermatochalasis, this is a condition in which excess skin bags down over the eyelid. It can cause some vision obstruction. It may be inherited, but it also occurs naturally with aging.

Creating a Crease

While many people embrace their monolid eye shape, some seek to create the double eyelid effect. This can be done with strategies and treatments that include:

  • Makeup: Asian makeup artists use eyeshadows and eyeliners to draw attention to the eyes, often with bright colors to make the eyes more of a focal point on the face even if they are narrow.
  • Tape or glue: Adhesives can create an artificial crease in the eye temporarily, giving it the appearance of a double lid or wider eye. The tape can make it more difficult to blink and affect tear production, all of which can have an impact on eye health.
  • Blepharoplasty: This double eyelid surgery can change the eye shape by adding an eyelid crease and removing skin. It can be combined with a procedure known as ptosis surgery, which strengthens the eyelid muscle, giving a more wide-eyed appearance.

Popularity of Eyelid Surgery

Blepharoplasty in the United States was among the top five most common cosmetic procedures in 2023, in part because of less-invasive procedures now available. More than 120,000 eyelid surgeries were completed, according to the American Society of Plastic Surgeons. It is a common procedure in Asian nations as well.

Summary

Monolids are part of the normal variation of human appearance. This eye shape doesn’t impact your vision and is an example of beautiful and diverse facial traits. Monolids are usually caused by your genetics but can also be caused by medical conditions.

In some instances and cultures, though, monolids are not preferred. In these cases, individuals may opt to lessen the appearance of a monolid with make-up or adhesives. There are also surgical ways to create a crease for the eye, so talk with your healthcare provider about the options.

13 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Lu TY, Kadir K, Ngeow WC, Othman SA. The Prevalence of Double Eyelid and the 3D Measurement of Orbital Soft Tissue in Malays and Chinese. Sci Rep. 2017 Nov 1;7(1):14819. doi:10.1038/s41598-017-14829-4

  2. Yong PT, Arif N, Sharanjeet-Kaur S, Hairol MI. Double eyelid tape wear affects anterior ocular health among young adult women with single eyelids. Int J Environ Res Public Health. 2020;17(21):7701. doi:10.3390/ijerph17217701

  3. Sun E, Kraus CL. The ophthalmic manifestations of Down syndrome. Children (Basel). 2023;10(2):341. doi:10.3390/children10020341

  4. Wozniak JR, Riley EP, Charness ME. Clinical presentation, diagnosis, and management of fetal alcohol spectrum disorder. Lancet Neurol. 2019;18(8):760-770. doi:10.1016/S1474-4422(19)30150-4

  5. Kilinc S, Yildiz M, Guven A. Associated clinical abnormalities among patients with Turner syndrome. North Clin Istanb. 2020;7(3):226-230. doi:10.14744/nci.2019.84758

  6. National Organization for Rare Diseases. Blepharophimosis, ptosis, epicanthus inversus syndrome.

  7. National Organization for Rare Disorders. Williams syndrome.

  8. El Bouchikhi I, Belhassan K, Moufid FZ, et al. Noonan syndrome-causing genes: molecular update and an assessment of the mutation rate. Int J Pediatr Adolesc Med. 2016;3(4):133-142. doi:10.1016/j.ijpam.2016.06.003

  9. Zhu Z, Genchev GZ, Wang Y, et al. Multivariate analysis and model building for classifying patients in the peroxisomal disorders X-linked adrenoleukodystrophy and Zellweger syndrome in Chinese pediatric patients. Orphanet J Rare Dis. 2023;18(1):102. doi:10.1186/s13023-023-02673-x

  10. Mount Sinai. Epicanthal folds.

  11. American Academy of Ophthalmology.Eyelid Surgery.

  12. Chen CC, Tai HC, Huang CL. Chen’s double eyelid fold ratio. Plast Reconstr Surg Glob Open. 2016;4(4):e681. doi:10.1097/GOX.0000000000000655

  13. American Society of Plastic Surgeons.Plastic Surgery Statistics 2023.

Monolids (Epicanthal Folds) and Their Causes (2)

By Kelly Burch
Burch is a New Hampshire-based freelance health writer with a bachelor's degree in communications from Boston University.

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