Ptosis (Blepharoptosis): Causes, Classification, Treatment

Ptosis, or blepharoptosis, is a pathological condition in which the upper eyelid droops below its normal anatomical position while in the primary gaze position.

The term originates from the Greek words blepharon (eyelid) and ptōsis (an act of descent).

Etiology

Blepharoptosis may be categorized in various ways concerning its pathogenetic, diagnostic, predictive, and therapeutic aspects.

Etiologically, upper eyelid ptosis may be classified into:

1. Congenital Ptosis

The condition typically presents as nonprogressive drooping of the upper eyelid. Unilateral ptosis accounts for 75 % of cases, while the bilateral form is asymmetrical.

Histopathological examination of isolated congenital myogenic ptosis reveals dysgenesis of the anterior part of the levator palpebrae superioris. Over time, the striated muscle fibers are lost, and loose connective tissue overgrows, impairing the levator’s ability to contract and relax.

2. Acquired Ptosis

This form of ptosis may arise due to various reasons, as outlined below.

• Neurological disorders. In such cases, ptosis develops secondary to impaired innervation of the upper eyelid muscles. The neural pathways involved primarily activate the oculomotor nerve (cranial nerve III) and the sympathetic nervous system. Damage to the oculomotor nerve is a common factor underlying both acquired and congenital forms of neurogenic ptosis. Microvascular ischemia is the leading cause of acquired damage to CNIII. It is linked to vasculopathic risk factors such as diabetes mellitus, hypertension, hyperlipidemia, and smoking. However, a healthcare professional should also investigate more serious causes, such as:
  • Posterior communicating aneurysms;
  • Giant cell arteritis;
  • Trauma or malignancies.

• Myasthenia gravis is an acquired autoimmune disease that may develop when acetylcholine receptor antibodies attack postsynaptic neuromuscular junctions. Ptosis of the upper eyelid is also the most common ocular symptom of myasthenia and is characterized by unilateral, bilateral, or alternating levator dysfunction.

Myogenic etiology: This category encompasses primary inherited myopathies accompanied by a chronic, progressive decline in the function of the levator palpebrae superiori, as well as secondary myopathies associated with other systemic conditions.

Primary hereditary myopathies include mitochondrial disorders and autosomal dominant or recessive inherited conditions.

Chronic progressive external ophthalmoplegia is the most common form of primary inherited myopathy. By the age of 30–40 years, such patients typically present with bilateral ptosis and ophthalmoplegia, which may be accompanied by neurosensory deafness and dysphagia.

Oculopharyngeal muscular dystrophy is a rare form of muscular dystrophy with an onset at 40–50 years of age. It is typically characterized by progressive ptosis and external ophthalmoplegia. This pathology is diagnosed through the identification of an autosomal dominant PABPN1 mutation in combination with systemic dysphagia and weakness in proximal extremities.

• Traumatic ptosis is a result of damage to the levator, its aponeurosis, Müller’s muscle, the frontalis muscle, or impairment of their innervation. Trauma may include any direct or indirect muscular damage, neurotoxic effects, indirect impact of scars or foreign bodies, iatrogenic injuries, damage to cranial nerves, or cicatrical changes in the skin.

Ptosis Classification

Clinically, blepharoptosis may be classified based on its severity:

• Mild: The upper eyelid lowers by 1.5–2.0 mm, and the margin does not overlap the pupil;
• Moderate: The upper eyelid overlaps half of the pupil;
• Severe: The upper eyelid lowers by approximately 4.0 mm, and the margin completely overlaps the pupil.

3D model of ptosis of upper eyelid of various severity:

Ptosis — first stage

Ptosis — second stage

Ptosis — third stage

Anatomic Pathology

Elevation of the upper eyelid is a complex process involving three different retractors, each innervated individually. Any direct or indirect impact on these muscles may trigger blepharoptosis.

The levator palpebrae superioris (upper eyelid levator) serves as an antagonist to the orbicularis oculi muscle. It originates from the lesser wing of the sphenoid bone and gives off the superior rectus muscle (inferiorly) and the obliquus superior capitis muscle (medially). At the level of the supraorbital margin, the levator palpebrae superioris transitions into a broad tendon that divides into anterior, middle, and posterior portions.

• The anterior portion penetrates the integument of the upper eyelid.
• The middle and posterior portions attach to the superior tarsal plate and the superior conjunctival fornix, respectively.

The anterior and posterior portions receive innervation from the superior branch of the oculomotor nerve, while the middle portion is innervated by the sympathetic fibers of the cervical sympathetic ganglion. The middle portion of the levator palpebrae superioris has been identified by some authors as an independent smooth muscle structure, referred to as the superior tarsal muscle or Müller’s muscle. It servesas a vertical mobility effector for the upper eyelid and works in conjunction with the levator palpebrae superioris.

The core of each eyelid is formed by a dense tarsal plate composed of fibrous connective tissue. For the upper eyelid, this plate typically measures 29–30 mm in length, 1 mm in thickness, and 10–12 mm in height.

The medial and lateral palpebral ligaments originate from the terminal portions of the upper and lower tarsal plates at their medial and lateral ends.

Diagnosis

1. Patient complaints: Individuals with a drooping upper eyelid often experience characteristic subjective symptoms. These include a reduced field of vision and the resulting difficulties with activities such as reading and driving. Additionally, headaches and persistent fatigue may occur due to the constant overuse of the frontalis muscle, which raises the eyebrow, as well as the neck flexor muscles, including the trapezius, which tilt the head.
2. Medical history:
   During an interview, a patient may report:

• Previous diseases affecting the organ of vision, traumatic injury to the eyelid, orbit, or head, or prior surgical procedures involving the eyelids;
• Diplopia, daily fluctuations in the position of the upper eyelid, increased general fatigue, chronic progressive external ophthalmoplegia, myotonic dystrophy, or a family history of ptosis;
• Recent trauma, including head injuries;
• Concomitant general medical conditions, such as disorders of nervous, endocrine, or cardiovascular systems, thyroid gland abnormalities, diabetes mellitus;
• A detailed pharmacological history.

3. Clinical tests: Visual acuity test (visometry); autokeratometry; measurement of intraocular pressure; slit lamp biomicroscope; ophthalmoscopy; visual field testing. Upper eyelid ptosis may be diagnosed by assessing the height of the palpebral fissure, the margin reflex distance, the performance of the levator palpebrae superioris, and the height of the superior palpebronasal fold. Slit lamp biomicroscopy evaluates the state of the conjunctiva, cornea, iris coloration, and the size and mobility of the pupil. Reactive blepharoptosis may also be triggered by conjunctivitis and keratopathy. Currently, myasthenia gravis in patients with blepharoptosis may be d iagnosed through preliminary tests to detect pathological muscle weakness in the eye (rest test, ice pack test), Tensilon test, blood serum tests for acetylcholine receptor antibodies, and electromyographic study.

Ptosis Treatment

Blepharoptosis should be managed based on its etiology, severity, and associated symptoms.

Medical Therapy

Certain forms of blepharoptosis may require medical therapy. Eye disorders linked to thyroid gland conditions may trigger drooping of the upper eyelid. Such cases necessitate corticosteroids and/or immunomodulator therapy to stabilize the eyelid for approximately 6–9 months prior to surgery.

As the levator function may vary greatly in myastenia patients, the dose of cholinesterase inhibitors and/or corticosteroids should be adjusted to stabilize the condition for 3–4 years before any corrective procedure.

Botulotoxin injected into the pretarsal area of the orbicularis oculi muscle may be effective to treat mild acquired aponeurotic ptosis or acquired neurogenic ptosis.

Surgical treatment

Blepharoptosis may be corrected using several approaches:

• Type 1: Enhancement of the function of the levator palpebrae superioris.
• Type 2: Suspension of the upper eyelid on the superior rectus muscle or the frontalis muscle.

Currently, suspension techniques are preferred when the levator function is weak, whereas average or strong muscular performance may only require levator resection.

Suspension techniques involve elevating the upper eyelid using the frontalis muscle or superior rectus muscle. This method of ptosis correction offers different variations and utilizes different kinds of sutures and autogenous tissues (muscles, sclera, dura, fascia lata, etc.). However, autogenous tissues generally yield insufficient results and increase the risk of relapse. That is why they are now rarely used in blepharosplasty. The fascia lata is the only exception to this trend.

Resection of the levator palpebrae superioris is another nosotropic approach to treating blepharoptosis. This surgical procedure anatomically restores the normal position of the upper eyelid. Severe blepharoptosis may require maximal levator resection. In such cases, the lateral horns of the aponeurosis and the Whitnall ligament are completely dissected.

Procedures aimed at reinforcing the levator palpebrae superioris may be further categorized into transcutaneous and transconjuctival levator resections. These techniques result in the formation of a fold, which shortens the tendon of the levator.