The palpebral fissure is the elliptic space between the medial and lateral
canthi
The canthus (pl. canthi, palpebral commissures) is either corner of the eye where the upper and lower eyelids meet. More specifically, the inner and outer canthi are, respectively, the medial and lateral ends/angles of the palpebral fissure.
T ...
of the two open
eyelid
An eyelid is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. The human eyel ...
s. In simple terms, it is the opening between the eyelids. In adult humans, this measures about 10 mm vertically and 30 mm horizontally.
Variations
Congenital dysmorphisms
It can be reduced (short, "narrow") in horizontal size by
fetal alcohol syndrome and in
Williams syndrome
Williams syndrome (WS) is a genetic disorder that affects many parts of the body. Facial features frequently include a broad forehead, underdeveloped chin, short nose, and full cheeks. Mild to moderate intellectual disability is observed in people ...
. The chromosomal conditions
trisomy 9
Full trisomy 9 is a lethal chromosomal disorder caused by having three copies (trisomy) of chromosome number 9. It can be a viable condition if trisomy affects only part of the cells of the body (mosaicism) or in cases of partial trisomy (triso ...
and
trisomy 21
A trisomy is a type of polysomy in which there are three instances of a particular chromosome, instead of the normal two. A trisomy is a type of aneuploidy (an abnormal number of chromosomes).
Description and causes
Most organisms that reprodu ...
(Down syndrome) can cause the palpebral fissures to be upslanted, whereas
Marfan syndrome
Marfan syndrome (MFS) is a multi-systemic genetic disorder that affects the connective tissue. Those with the condition tend to be tall and thin, with long arms, legs, fingers, and toes. They also typically have exceptionally flexible joints a ...
can cause a downslant. An increase in vertical height can be seen in genetic disorders such as
cri-du-chat syndrome
Cri du chat syndrome is a rare genetic disorder due to a partial chromosome deletion on chromosome 5. Its name is a French term ("cat-cry" or " call of the cat") referring to the characteristic cat-like cry of affected children. It was first des ...
.
Acquired
The fissure may be increased in vertical height in
Graves' disease
Graves' disease (german: Morbus Basedow), also known as toxic diffuse goiter, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyr ...
, which is manifested as
Dalrymple's sign Dalrymple's sign is a widened palpebral (eyelid) opening, or eyelid spasm, seen in thyrotoxicosis (as seen in Graves' disease, exophthalmic goitre and other hyperthyroid conditions), causing abnormal wideness of the palpebral fissure. As a resul ...
. It is seen in disorders such as cri-du-chat syndrome.
In animal studies using four times the therapeutic concentration of the ophthalmic solution
latanoprost
Latanoprost, sold under the brand name Xalatan among others, is a medication used to treat increased pressure inside the eye. This includes ocular hypertension and open angle glaucoma. It is applied as eye drops to the eyes. Onset of effects i ...
, the size of the palpebral fissure can be increased. The condition is reversible. Latanoprost is a
prostaglandin F receptor
Prostaglandin F receptor (FP) is a receptor belonging to the prostaglandin (PG) group of receptors. FP binds to and mediates the biological actions of Prostaglandin F2α (PGF2α). It is encoded in humans by the ''PTGFR'' gene.
Gene
The ''PTG ...
agonist
An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...
.
United States Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food s ...
(Nov. 2006)
Xalatan (latanoprost ophthalmic solution) 0.005% (50 μg/mL)
Accessed 5 Feb 2011.
See also
*
Blepharophimosis
Blepharophimosis is a congenital anomaly in which the eyelids are underdeveloped such that they cannot open as far as usual and permanently cover part of the eyes. Both the vertical and horizontal palpebral fissures (eyelid openings) are shortene ...
References
External links
Facial Neurological Examinationfrom University of Toronto
{{Authority control
Human eye anatomy