Table 11-1 lists the most common causes of acquired ptosis. Neurogenic ptosis requires careful attention to associated abnormalities in pupillary size and extraocular movements. Bilateral ptosis may be the only manifestation of a nuclear CN III palsy (see Chapter 7). Cerebral ptosis, which is a rare form of ptosis, occurs in association with a lesion of the cerebral (typically right) hemisphere. The ptosis may be bilateral or unilateral, and in the majority of cases, it is transient, lasting up to several months.
Suspicion of the presence of systemic disorders such as myasthenia gravis, chronic progressive external ophthalmoplegia, oculopharyngeal dystrophy, and myotonic dystrophy (discussed in Chapter 14) requires questions regarding the patient’s general strength, fatigability, dysphagia, and family history. Botulism leads to bilateral ptosis associated with poorly reactive pupils and ophthalmoplegia. Such patients also have associated facial paralysis and generalized proximal muscle weakness. Areflexia, ataxia, and ophthalmoplegia characterize Miller Fisher syndrome, a variant of Guillain-Barré syndrome (discussed later in this chapter). In addition to bilateral ptosis, patients with Miller Fisher syndrome may also have facial diplegia, as well as respiratory and swallowing difficulties. Long-term use of steroid eyedrops is thought to lead to ptosis as a localized steroid-induced myopathy of the levator muscle. Posterior sub-Tenon steroid injections have also been associated with ptosis. The levator muscle, aponeurosis, or the insertion site of the aponeurosis may be adversely affected by such injections.
Levator aponeurotic defects have been found to be the most frequent cause of acquired ptosis, supplanting the idea that acquired ptosis is the result of aging (“senile” ptosis). This ptosis is caused by stretching, dehiscence, or disinsertion of the levator aponeurosis. Aponeurotic ptosis may occur with frequent eye rubbing or prolonged contact lens use, and may also be caused or exacerbated by intraocular surgery, perhaps resulting from use of an eyelid speculum. Because the levator muscle itself is healthy, levator function is usually normal. Patients with aponeurotic defects usually have a high eyelid crease.
Table 11-1 Causes of Acquired Ptosis
Traumatic and mechanical causes of acquired ptosis are generally evident from inspection of the eyelids and require appropriate medical or surgical therapy.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.