Dermatochalasis commonly affects the elderly, although sometimes it is congenitally acquired. The elderly version may begin to develop as early as 40 years of age, and it continues to progress with age. The congenital version may begin around 20 years of age. There is no racial predisposition towards developing dermatochalasis, and men and women are equally affected.

Studies have recorded an incidence of about 3–5 cases per 1,000 newborn babies.

There are various causes of madarosis.

- Ophthalmological conditions: blepharitis is an infection of the eyelid. Anterior blepharitis is either "staphylococcal blepharitis,"or "seborrhoeic blepharitis" and posterior blepharitis is due to the meibomian gland.

- Dermatologic conditions: there are multiple types of dermatological conditions that can result in madarosis. These include Atopic dermatitis, Seborrhoeic dermatitis atopic dermatitis, and Psoriasis on the eyelids can result in madarosis. Others include: frontal fibrosing alopecia, ulerythema ophryogenes, acne rosacea, telogen effluvium, follicular mucinosis, and cutaneous sarcoidosis.

- Nutritional defects: Severe malnutrition can cause chronic hair loss. Hypoproteinemia causes hair loss by early onset of telogen. Zinc deficiencies like acrodermatitis enteropathica, can lead to the loss of eyebrow/eyelash hair. Other deficiencies like biotin and iron make it possible for loss of hair as well.

- Infections: There are many bodily infections that can cause the loss of eyelashes/eyebrows. The most common infection may be leprosy, such as lepromatous leprosy. Syphilis or other viral infections like herpes or HIV can cause the loss of eye hair as well. Fungal infections, like paracoccidioidomycosis, trichophyton, or microsporum, are also possible infection causes.

- Trauma: Most trauma injuries cause madarosis from the psychological standpoint, known as trichotillomania

- Drugs/Medications: Crack cocaine or chemotherapy drugs. Other drugs include:propranolol, valproic acid, barbiturates, MMR vaccine, botulinum toxin, epinephrine, antithyroid drugs, anticoagulants, and lipid-lowering drugs

- Genetics

- Autoimmune disorders: alopecia areata, discoid lupus erythematosus, chronic cutaneous lupus erythmatosus, Graham-Little syndrome, and Parry Romberg syndrome

- Other diseases: hypothyroidism, hyperthyroidism, hypoparathyroidism, hypopituitarism, and amyloidosis

There only prevention method is determining the underlying condition before treatment options are too late.

Ectropion in dogs usually involves the lower eyelid. Often the condition has no symptoms, but tearing and conjunctivitis may be seen. Breeds associated with ectropion include the Cocker Spaniel, the Saint Bernard, the Bloodhound, the Clumber Spaniel, and the Basset Hound. It can also result from trauma or nerve damage. Treatment (surgery) is recommended only if there is chronic conjunctivitis or if there is corneal damage. A small part of the affected lid is removed and then the lid is sewn back together.

There is currently researching being done to find more treatments dependent on the different pre-existing conditions.

Studies are being conducted in which madarosis can be related to malignancy. A study by Groehler and Rose found that there was a statistical significance between these two. They concluded that patients malignancy lesions on the eyelid have a higher chance of having madarosis than a patient with a benign lesion. They stated that despite the fact that it is significant, the absence of madarosis does not mean the lesion cannot be malignant.

In many leprosy cases, madarosis is a symptom or a quality after diagnosis. However, in India, leprosy is common and researchers report a case of madarosis before diagnosis of leprosy with no skin lesions, only madarosis. This allowed for quicker treatment.

A main reason many people have madarosis is due to the chemotherapy drugs. There was a clinical trial in 2011 that tested an eyelash gel called bimatoprost. This gel enhanced the eyelashes in quantity and thickness. They tested this on 20 breast cancer patients who were undergoing chemotherapy. Results seemed positive, in that the group of people who used the gel had growth of eyelashes after the chemotherapy drugs.

People with dermatochalasis often also have blepharitis, a condition caused by the plugging of glands in the eye that produce lubricating fluid (meibomian glands). Dermatochalasis can be severe enough that it pushes the eyelashes into the eye, causing entropion.

Weakness in the orbital septum may cause the herniation of the orbital fat pads. This is observed as the presence of bulges (fat pads) in the soft tissue of the baggy eyes.

Punctate epithelial erosions may be seen with different disorders:

- Rosacea

- Dry-eye syndrome

- Blepharitis

- Acute bacterial conjunctivitis

- Trauma

- Exposure keratopathy from poor eyelide closure

- Ultraviolet or chemical burn

- Contact lens-related disorder such as toxicity or tight lens syndrome

- Trichiasis

- Entropion or ectropion

- Floppy eyelid syndrome

- Chemotherapy i.e. cytosine arabinoside

- Thygeson's Superficial Punctate Keratopathy

Many environmental conditions have also been known to cause anophthalmia. The strongest support for environmental causes has been studies where children have had gestational-acquired infections. These infections are typically viral. A few known pathogens that can cause anophthalmia are Toxoplasma, rubella, and certain strains of the influenza virus. Other known environmental conditions that have led to anophthalmia are maternal vitamin A deficiency, exposure to X-rays during gestation, solvent abuse, and exposure to thalidomide.

Port-wine stains were shown to be caused by a somatic activating c.548G→A mutation in the GNAQ gene. An association with RASA1 has also been described.

Periorbital hyperpigmentation is characterized by dark circles around the eyes, which are common, often familial, and frequently found in individuals with dark pigmentation or Mediterranean ancestry. Atopic dermatitis patients may also exhibit periorbital pigmentation (allergic shiners) due to lower eyelid venous stasis, and treatment is ineffective.

An ectopic cilia is a special type of distichia. It is usually found in younger dogs. Commonly affected breeds include Poodles, Golden Retrievers, and Shih Tzus. The eyelash exits through the conjunctiva of the eyelid facing toward the eye, usually at the middle of the upper eyelid. It can cause intense pain and corneal ulcers. Treatment is surgery or cryotherapy.

Ectropion is a medical condition in which the lower eyelid turns outwards. It is one of the notable aspects of newborns exhibiting congenital Harlequin-type ichthyosis, but ectropion can occur due to any weakening of tissue of the lower eyelid. The condition can be repaired surgically. Ectropion is also found in dogs as a genetic disorder in certain breeds.

Cryptophthalmos is a rare congenital anomaly in which the skin is continuous over the eyeball with absence of eyelids. It is classified into three types: complete, incomplete and abortive. Failure of eyelid separation can be associated with maldevelopment of the underlying cornea and microphthalmia. Cryptophthalmos usually occurs on both sides and occurs in association with other multiple malformations collectively referred to as Fraser syndrome.

An interstitial deletion of chromosome 14 has been known to occasionally be the source of anophthalmia. The deletion of this region of chromosome has also been associated with patients having a small tongue, and high arched palate, developmental and growth retardation, undescended testes with a micropenis, and hypothyroidism. The region that has been deleted is region q22.1-q22.3. This confirms that region 22 on chromosome 14 influences the development of the eye.

A distichia is an eyelash that arises from an abnormal spot on the eyelid. This abnormality, attributed to a genetic mutation, is known to affect dogs and humans. Distichiae (the abnormal eyelash) usually exit from the duct of the meibomian gland at the eyelid margin. They are usually multiple and sometimes more than one arises from a duct. They can affect either the upper or lower eyelid and are usually bilateral. The lower eyelids of dogs usually have no eyelashes.

Distichiae usually cause no symptoms because the lashes are soft, but they can irritate the eye and cause tearing, squinting, inflammation, and corneal ulcers and scarring. Treatment options include manual removal, electrolysis, electrocautery, cryotherapy, and surgery.

Epiblepharon is characterised by a congenital horizontal fold of skin near the margin of the upper or lower eyelid caused by the abnormal insertion of muscle fibres. This extra fold of skin redirects the lashes into a vertical position, where they may contact the globe. This is found most commonly in Asian individuals, especially children.

BPES is very rare: only 50-100 cases have been described. It affects slightly more males than females.

Trichiasis in dogs is hair from the eyelid growing in the wrong direction and rubbing on the eye, causing irritation. It usually occurs at the lateral upper eyelid, especially in the English Cocker Spaniel. Trichiasis also refers to hair from a nasal fold rubbing on the eye. This type of trichiasis can be flattened by rubbing petroleum jelly onto it, but surgery is sometimes necessary for permanent correction.

Epicanthic folds appear in East Asians, Southeast Asians, Central Asians, North Asians, some South Asians, Polynesians, Micronesians, Indigenous Americans (as well as Mestizos), the Khoisan, Malagasy, occasionally Europeans (e.g., Scandinavians, Hungarians, Samis, Irish and Poles) and among Nilotes.

Anthropologist Carleton S. Coon states that the "median fold" occurs in Finnic and Slavic populations, while the "true inner or mongoloid fold" appears in populations of the east and the far north.

Entropion is a medical condition in which the eyelid (usually the lower lid) folds inward. It is very uncomfortable, as the eyelashes continuously rub against the cornea causing irritation. Entropion is usually caused by genetic factors. This is different from when an extra fold of skin on the lower eyelid causes lashes to turn in towards the eye (epiblepharon). In epiblepharons, the eyelid margin itself is in the correct position, but the extra fold of skin causes the lashes to be misdirected. Entropion can also create secondary pain of the eye (leading to self trauma, scarring of the eyelid, or nerve damage). The upper or lower eyelid can be involved, and one or both eyes may be affected. When entropion occurs in both eyes, this is known as "bilateral entropion." Repeated cases of trachoma infection may cause scarring of the inner eyelid, which may cause entropion. In human cases, this condition is most common to people over 60 years of age.

It is encountered more commonly in younger rather than older individuals.

Risk factors of progressive and severe thyroid-associated orbitopathy are:

- Age greater than 50 years

- Rapid onset of symptoms under 3 months

- Cigarette smoking

- Diabetes

- Severe or uncontrolled hyperthyroidism

- Presence of pretibial myxedema

- High cholesterol levels (hyperlipidemia)

- Peripheral vascular disease

Trichiasis (, or , ) a medical term for abnormally positioned eyelashes that grow back toward the eye, touching the cornea or conjunctiva. This can be caused by infection, inflammation, autoimmune conditions, congenital defects, eyelid agenesis and trauma such as burns or eyelid injury. It is the leading cause of infectious blindness in the world.

Standard treatment involves removal or destruction of the affected eyelashes with electrology, specialized laser, or surgery. In many cases, removal of the affected eyelashes with forceps resolves the symptoms, although the problem often recurs in a few weeks when the eyelashes regrow. Severe cases may cause scarring of the cornea and lead to vision loss if untreated. Mild cases may not require treatment.

Repeated cases of trachoma infection may cause trichiasis.

Posterior misdirection of normal lashes most frequently affects lower lid.

Lid lag is the static situation in which the upper eyelid is higher than normal with the globe in downgaze. It is most often a sign of thyroid eye disease, but may also occur with cicatricial changes to the eyelid or congenital ptosis. Lid lag differs from Von Graefe's sign in that the latter is a dynamic process.It can also be the manifestaition of chemosis (swelling (or edema) of the conjunctiva)

Many fetuses lose their epicanthic folds after three to six months of gestation.