Droopiness of the upper eyelid (ptosis) results from a deficiency in the action of the elevating muscle (levator muscle) or its tendon (levator aponeurosis).
Congenital ptosis (either inherited or an isolated birth defect) is almost always caused by the inadequate development of the levator muscle itself and is noted shortly after birth. Rarely, adult ptosis may be caused by muscular disease as well, especially in such degenerative conditions as myasthenia gravis.
Surgery for muscular ptosis is directed at tightening the levator muscle tissue (by partial resection) or, in severe instances, by connecting the paralyzed lifting mechanism to the healthier muscles of the eyebrow via an internal suspension system. While such procedures can lift the eyelid higher, the dystrophic muscle can never be made normal and so some degree (slight to marked) of functional deficiency (both opening and closing) will always persist.
Fortunately, the vast majority of cases of acquired ptosis (that is, onset after birth) are related to a deterioration of the levator aponeurosis (tendon) rather than the muscle itself, which remains healthy. The aponeuroses develops areas of thinning, localized tears, or sometimes complete detachment and is no longer able to transmit the lift of the levator muscle to the margin of the eyelid.
The supporting structure of the lower eyelid may be likened to a hammock, with a cartilage-like central stiffener element (tarsal plate) attached by two tendons (canthal tendons) to the socket bone on either side of the eye. If the tendons become stretched due to wear-and-tear or from trauma or even other eyelid surgery, the lid may lose its normal adherence to the eye surface and sag outward, a condition known as ectropion.
In the presence of ectropion, wind and dust may dry out and irritate the delicate tissue lining the back of the exposed eyelid. Tearing develops when the tear duct drain on the edge of the eyelid drifts away from the eyeball and can no longer pick up the moisture. Eventually, an eye with ectropion may develop scarring.
Ectropion eyelid surgery is designed to tighten the stretched tendons and shorten the stretched lid. If the tendons have become too shredded, an entirely new means of support may be fashioned by borrowing from nearby healthy tissues.
Cicatricial ectropion indicates a condition in which the skin below the eyelid has been scarred and tightened, thus exerting a constant downward pull on the eyelid support system. In such cases, a skin graft may be necessary.
The most common form of lower eyelid entropion (involutional entropion) develops from a weakening and stretching of the tendons supporting the eyelids to the orbital rim of bone. In addition, a tendon-like sheath below the tarsal plate tears or stretches, thus allowing the unstable eyelid to rotate inward against the eye. Pain from lashes and skin rubbing against the cornea can be severe, and the risk from entropion to vision is immediate.
Another form of entropion (cicatricial entropion) is associated with scarring from trauma or infection on the back lining of the eyelid and/or within the internal structure of the eyelid. While uncommon in the United States, this variant of entropion is a leading cause of blindness in underdeveloped countries.
Surgical correction on the more common type of entropion entails rotating the lid margin back to its normal position by tightening both the canthal tendons and the tendon-like sheath. In cicatricial entropion, grafting of tissue from donor sources and internal eyelid rearrangement may be needed.
Lower eyelid retraction, like lower lid ectropion, is caused by a compromised support system but also by the shrinkage of any of several tissue layers (skin, muscle, retractors). This combination of horizontal stretchiness and vertical shortening causes the lower lid to pull downward (retraction) below the cornea, thereby exposing the white of the eye (scleral show).
Lid retraction can occur naturally, with aging, with thyroid disease, or as a consequence of overdone transcutaneous cosmetic blepharoplasty surgery (as shown in the photos below).
There is no one all-inclusive approach to the correction of lower eyelid retraction, and not all cases can be remedied. Each operation must be highly individualized using techniques such as:
- support system reinforcement (canthoplasty)
- grafting of an internal spacer (Alloderm, ear cartilage, hard palate)
- skin grafting
- SOOF or midface lift
- augmentation of insufficient bony support below the eye
- newer techniques still under development
Lid retraction associated with thyroid disease is related to the pull of overactive eyelid muscles; corrective techniques are directed at lessening their pull.
In recent years, the incidence of eyelid skin cancer has escalated considerably due to the effects of excessive sun exposure in a population previously unaware of its harmful nature. Effective diagnosis and treatment are crucial since even small tumors can destroy the delicate lid structure necessary for maintaining the health of the eye.
Eyelid cancers may present in assorted forms, including as areas of elevation, depression, redness, scaliness, or dark or light discoloration. Some tumors grow quickly, while others may take several years to reach noticeable size. Not all are elevated. Any sore that refuses to heal is suspect.
The most common eyelid cancer is basal cell carcinoma, which accounts for more than 90% of cancers in this area. While it is unusual for this tumor to metastasize widely, it can cause considerable destruction of eyelid structure, function, and appearance by direct spread. Other eyelid cancers may be much more aggressive and malignant.
Any suspicious lesion should be removed immediately and examined under the microscope. Biopsy is a quick and easy procedure. Once a diagnosis has been made, complete removal is the primary goal of treatment. Burning, freezing, or simply scraping the skin is not recommended over surgery since there is no way to assure that the lesion has been fully removed.
The method of surgical reconstruction is dictated by the size and location of the resulting defect after the cancer has been excised. When applied properly, modern techniques allow for the recreation of a near-normal appearing and functioning eyelid.
A chalazion is a chronic inflammation (not infection) of an eyelid oil gland that stimulates the formation of a surrounding cyst.
A chalazion may appear suddenly (and be confused with a stye) or slowly over many days. While a chalazion may shrink over several weeks and become painless, its core frequently remains intact.
Sooner of later, the cyst flares up again and again and may gradually deform the eyelid and distort the eyelashes.
Chalazion removal is a minor surgical procedure that takes about ten minutes.