Involutional Ptosis

Involutional ptosis is defined by specific clinical features, including constant ptosis, good levator function, high or absent skin crease, and increased lid excursion on downgaze. It is generally caused by dehiscence or disinsertion of the levator aponeurosis from the superior tarsal plate. Müller’s muscle, once thought to be a weak contributor to upper eyelid elevation, may be a dominant regulator of eyelid height, and thus important in the aetiology of involutional ptosis. Diagnosis relies on history taking, measurement of margin reflex distance, levator muscle function, orbicularis function; evaluation of pupillary light reactions and extraocular motility are mandatory for diagnosis of exclusion. Prolonged eyelid oedema, long-term contact lens wear, previous eye surgery, and blunt trauma may also cause involutional ptosis at any age. Müller’s muscle is also thought to be involved with the aetiology of involutional ptosis. The two favoured techniques for involutional ptosis repair are external aponeurosis advancement (ALR) and Müller muscle-conjunctiva resection (MMCR). ALR is preferred in patients with evident aponeurosis disinsertion, severe ocular surface cicatricial disease, shortened fornices, and reduced levator function. MMCR is favoured for cases of mild to moderate ptosis with good levator function, as it is predictable, provides a reliable cosmetic outcome, and has a low reoperation rate. Alternative techniques are the posterior approach white-line advancement and the tarsoconjuncticomüllerectomy (TCM). This chapter will detail two additional conditions that carry similar aetiology and management: ptosis in anophthalmic patients and blepharochalasis syndrome. In anophthalmic patients, volume deficit must be corrected before any eyelid surgery, and anterior approach levator advancement is usually preferred. The blepharochalasis syndrome is characterised by recurrent, nonpainful, episodes of eyelid oedema, resulting in thinning and atrophy of the upper eyelid. Common sequelae include ptosis due to aponeurosis disinsertion and laxity of the lateral canthal tendon.