Ptosis

Ptosis is an abnormally low position (drooping) of the upper eyelif
The drooping may be worse after being awake longer, when the individual's muscles are tired.
This condition is sometimes called "lazy eye", but that term normally refers to amblyopia.
If severe enough and left untreated, the drooping eyelid can cause other conditions, such as amblyopia or astigmatism.
This is why it is especially important for this disorder to be treated in children at a young age, before it can interfere with vision development.

Ptosis occurs when the muscles that raise the eyelid (levator and Müller's muscles) are not strong enough to do so properly. It can affect one eye or both eyes and is more common in the elderly, as muscles in the eyelids may begin to deteriorate. One can, however, be born with ptosis. Congenital ptosis is hereditary in three main forms.

Causes of congenital ptosis remain unknown. Ptosis may be caused by damage/trauma to the muscle which raises the eyelid, or damage to the nerve (3rd cranial nerve (oculomotor nerve)) which controls this muscle. Such damage could be a sign or symptom of an underlying disease such as diabetes mellitus, a brain tumor, and diseases which may cause weakness in muscles or nerve damage, such as myasthenia gravis. Exposure to the toxins in some snake and insect venoms, such as that of the black mamba, may also cause this effect.

Ptosis can be caused by the apneurosis of the levator muscle, nerve abnormalities, trauma, inflammation or lesions of the lid or orbit. 
Dysfunctions of the levators may occur as a result of a lack of nerve communication being sent to the receptors due to antibodies needlessly attacking and eliminating the neurotransmitter.
Ptosis may be due to a myogenic, neurogenic, aponeurotic, mechanical or traumatic cause and it usually occurs isolated, but may be associated with various other conditions, like immunological, degenerative, or hereditary disorders, tumors, or infections

Acquired ptosis is most commonly caused by aponeurotic ptosis. This can occur as a result of senescence, dehiscence or disinsertion of the levator aponeurosis. Moreover, chronic inflammation or intraocular surgery can lead to the same effect. Also, wearing contact lenses for long periods of time is thought to have a certain impact on the development of this condition.
Congenital neurogenic ptosis is believed to be caused by the Horner syndrome. [5] In this case, a mild ptosis may be associated with psilateral ptosis, iris and areola hypopigmentation and anhidrosis due to the paresis of the Mueller muscle. Acquired Horner syndrome may result after trauma, neoplastic insult, or even vascular disease.
Ptosis due to trauma can ensue after an eyelid laceration with transection of the upper eyelid elevators or disruption of the neural input.
Other causes of ptosis include eyelid neoplasms, neurofibromas or the cicatrization after inflammation or surgery. Mild ptosis may occur with aging.

Classification
Depending upon the cause it can be classified into:
Neurogenic ptosis which includes oculomotor nerve palsy, Horner's Syndrome, Marcus Gunn jaw winking syndrome, IIIrd cranial nerve misdirection.
Myogenic ptosis which includes myasthenia gravis, myotonic dystrophy, ocular myopathy, simple congenital ptosis, blepharophimosis syndrome
Aponeurotic ptosis which may be involutional or post-operative.
Mechanical ptosis which occurs due to edema or tumors of the upper lid
Neurotoxic ptosis which is a classic symptom of envenomation[7] by elapids such as cobras,[8] or kraits.[9] Bilateral ptosis is usually accompanied by diplopia, dysphagia and/or progressive muscular paralysis. Regardless, neurotoxic ptosis is a precursor to respiratory failure and eventual suffocation caused by complete paralysis of the thoracic diaphragm. It is therefore a medical emergency and immediate treatment is required.
pseudo ptosis due to:1-Lack of lid support:Empty socket or atrophic globe. 2-Higher lid position on the other side: As in lid retraction
Treatment

 

Aponeurotic and congenital ptosis may require surgical correction if severe enough to interfere with vision or if cosmesis is a concern. Treatment depends on the type of ptosis and is usually performed by an ophthamolic plastic and reconstructive surgeon, specializing in diseases and problems of the eyelid.

Surgical procedures include:

Levator resection
Müller muscle resection
Frontalis sling operation
Non-surgical modalities like the use of "crutch" glasses or special Scleral contact lenses to support the eyelid may also be used.

Ptosis that is caused by a disease will improve if the disease is treated successfully.

 

Overview of Upper Eyelid Surgeries

There are two 'main' surgeries that may be performed on the upper eyelid. This section addresses Ptosis  which is the medical term for drooping of the upper eyelid; it may affect one or both eyes. The other surgery of the upper eyelid addresses excess skin  is repaired by blepharoplasty.

 

 

 

 

Overview of Upper Eyelid Surgeries

There are two 'main' surgeries that may be performed on the upper eyelid. This section addresses Ptosis  which is the medical term for drooping of the upper eyelid; it may affect one or both eyes. The other surgery of the upper eyelid addresses excess skin  is repaired by blepharoplasty.

 

 

 

 

 

Graves' disease is an autoimmune disease. It most commonly affects the thyroid, causing it to grow to twice its size or more (goiter), be overactive, with related hyperthyroid symptoms such as increased heartbeat, muscle weakness, disturbed sleep, and irritability. It can also affect the eyes, causing bulging eyes (exophthalmos). It affects other systems of the body, including the skin and reproductive organs. It affects up to 2% of the female population, often appears after childbirth, and has a female:male incidence of 5:1 to 10:1. It has a strong hereditary component; when one identical twin has Graves' disease, the other twin will have it 25% of the time. Smoking and exposure to second-hand smoke is associated with the eye manifestations but not the thyroid manifestations. Diagnosis is usually made on the basis of symptoms, although thyroid hormone tests may be useful, particularly to monitor treatment.

Heredity is the passing of traits to offspring (from its parent or ancestors). This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause a species to evolve. The study of heredity in biology is called genetics, which includes the field of epigenetics.

Edema is an abnormal accumulation of fluid beneath the skin, or in one or more cavities of the body. Generally, the amount of interstitial fluid is determined by the balance of fluid