The normal upper eyelid typically assumes a position midway between the pupil and the superior limbus. Any upper scleral show is always abnormal.

The hallmark of MG is variability. Essentially all patients with ptosis will complain, if prompted, that their ptosis is worse toward the end of the day simply because their frontalis muscles tire out from raising the brows to clear the visual axis. Patients with MG will usually report that their ptosis changes throughout the day and also changes sides. Many patients with myasthenic ptosis will also complain of diplopia unless the ptosis is severe enough to block one visual axis. Questions to ask and document in such patients include:

Frequently, patients will not volunteer information regarding muscle weakness, dysphagia or shortness of breath to their ophthalmologist. However, these questions must be asked by the clinican, since it is crucial in any patient who presents with so-called bulbar symptoms (dysphagia or respiratory difficulties) to refer promptly for treatment to avoid a myasthenic crisis.

Figure 1A. Myasthenic ptosis. Note that the patient also has left extropia.   Figure 1B. Immediately following ice application to the left eyelid for several minutes. Note the significant improvement in both the ptosis and extropia.

If MG is suspected as the etiology of the ptosis, a variety of tests (with approximate percentage of sensitivity noted) are available: 

Chest CT and thyroid function tests should also be obtained in all patients.

Many patients with myasthenic ptosis also have an external ophthalmoplegia, although a significant number will simply present with isolated ptosis. Even if external ophthalmoplegia and strabismus is present, some patients will not complain of diplopia because their ptosis effectively blocks one visual axis. Patients with myasthenic ptosis will also frequently have orbicularis oculi muscle weakness that may manifest as lagophthalmos. 

Testing for MG varies between centers. Some still advocate the use of edrophonium (Tensilon), although such testing must be carried out with adequate resuscitation equipment readily available. Other experts recommend the combination of acetylcholine receptor antibody testing and single-fiber electromyography of the orbicularis oculi or frontalis muscles. Of note, Medicare has recently mandated that only the binding antibody will be reimbursed, since it is the most sensitive for picking up MG; if the clinician is not specific or reflexively orders all three available antibody tests (binding, blocking and modulating), an irate patient with an unpaid laboratory bill may show up on the doorstep. 

Figure 2. Top: A patient presents with ptosis, L>R. Bottom: On attempted upgaze, a firm bulge appears in the left upper eyelid. Palpation revealed a rubbery mass. Figure 3. Above: Saggital MRI shows a mass infiltrating the levator and preaponeurotic fat. Biopsy was consistent with extranodal marginal zone B-cell-mucosa-associated lymphoid tissue lymphoma.

All patients with ptosis should undergo careful examination of the conjunctiva and superior cul-de-sac, and the presence or absence of globe malposition (ex/enophthalmos, hyper/hypoglobus) must be documented. Eyelid eversion should also be performed. In younger patients, occult foreign bodies (especially contact lenses) can on occasion erode through the conjunctiva into upper eyelid tissue and present clinically as a droopy lid. In older patients, lymphoma should always be suspected. If a mass is indeed palpated, imaging of the orbit is warranted. If any abnormal-appearing tissue is noted intraoperatively during ptosis repair, it should be sent for histopathologic analysis.

Chronic progressive external ophthalmoplegia is an umbrella term for a variety of mitochondrial disorders that present with slowly progressive ptosis and external ophthalmoplegia. In contrast to many patients with MG, patients with CPEO rarely complain of diplopia because of the chronic and symmetric nature of their external ophthalmoplegia. In early stages, the diagnosis can be difficult to make clinically. In late stages, the almost frozen globes and severe ptosis present less of a clinical challenge. Differentiation of CPEO from MG may at times prove frustrating, although two findings are highly suggestive of MG: variability and orbicularis oculi weakness. Over time, patients with CPEO also develop atrophy of the facial muscles, resulting in a mask-like facies that is not seen with MG.

Because CPEO is a mitochondrial disease, patients are at risk for life-threatening co-morbidities, most commonly cardiac in nature. The hallmark of CPEO coupled with cardiac disease is Kearns-Sayre syndrome (KSS). Patients with KSS invariably present by the late teens or early twenties and are at significant risk for high-grade cardiac conduction defects, which may result in sudden cardiac death. All patients with suspected KSS (and for that matter, all patients with suspected CPEO) should undergo urgent cardiologic evaluations. In addition, patients with suspected KSS should have a complete retinal examination; the presence of a pigmentary retinopathy (sometimes incorrectly described as “RP-like”) supports the diagnosis. Definitive diagnosis of CPEO typically requires a muscle biopsy for routine histopathology, special staining, and possibly electron microscopy. The goal of ptosis correction is to just clear the visual axis without causing excessive exposure keratopathy. 

Figure 4. Chronic progressive external ophthalmoplegia. A young woman with pigmentary retinopathy was referred for ptosis repair. She denied diplopia. Examination revealed severe external ophthalmoplegia consistent with CPEO. She was referred for cardiac workup.

Patients often notice asymmetry of the eyelids (“The lids just don’t look right”), but may then incorrectly conclude that one side is droopy when, in fact, the contralateral side is abnormal. 

The normal upper eyelid typically assumes a position midway between the pupil and the superior limbus. Any upper scleral show is always abnormal. (Remember that lower eyelid scleral show often occurs as a normal finding in patients with shallow orbits). Furthermore, an eyelid position at the superior limbus is probably also abnormal.

Figure 5. This teenager was referred for left ptosis. Lid retraction was noted on the right. Initial thyroid function testing was normal, but on repeated testing several months later, hyperthyroidism was present.

As noted earlier, all patients with upper lid retraction should undergo eyelid eversion and examination of the superior cul-de-sac. Lid lag on downgaze (von Graefe’s sign if associated with TED; pseudo-von Graefe’s sign for all other causes) should be looked for. Occasionally, aberrant CN-III regeneration or an old facial nerve palsy may present as unilateral lid retraction.

All patients presenting with lid retraction should undergo thyroid function testing. In most cases, a selective (3rd generation) TSH suffices. Some clinicians also obtain a thyroid-stimulating antibody (TSI) level, positing that this may be elevated in euthyroid patients and may prove to be a reliable early marker of subsequent dysfunction. If the TSH and TSI are normal, the patient should be retested every six months for two to three years, or sooner if he becomes systemically symptomatic. Up to 10 percent of patients with clinically obvious TED can be euthyroid on presentation. Of euthyroid patients, 25 percent will develop thyroid function testing abnormalities within one year, and 50 percent will do so within five years.

Ptosis is a common condition and, fortunately, the majority of etiologies are benign. However, a few history and examination points can rule out dangerous causes of ptosis. The simple mantra of “upper lid, pupils, and EOMs–if one is abnormal check the other two” cannot be overemphasized.  REVIEW