Ophthalmology: Eyelid problems

Basic eyelid anatomy

It's worth being aware of some basic eyelid anatomy so that you can try to work out where the problem lies. From superficial to deep, the eyelid consists of skin, subcutaneous tissue, the obicularis oculi muscle, the orbital septum (a membranous sheet continuous with the periosteum), tarsal plates, smooth muscle, and finally, conjunctiva. The upper lid also receives the insertion of the levator palpebrae superioris muscle which raises the lid.

The skin is thin and contains many sebaceous glands and small sweat glands. Remember that dermatological problems can also affect the skin of eyelids. The obicularis oculi muscle is important in facial expression, and contraction of the muscle closes the eyelids; its nerve supply is from the temporal and zygomatic branches of the facial nerve. The orbital septum is a fibrous sheet that originates from the orbital periosteum and serves as a barrier between the orbit and the eyelid to limit the spread of infection and bleeding. The levator muscle originates in the apex of the orbit and contains a muscular portion about 40 mm long and an aponeurosis 14-20 mm long.

Dehiscence of this aponeurosis is an important cause of acquired ptosis (drooping of the eyelid). The levator muscle is supplied by the oculomotor (third cranial) nerve. Just underneath the levator is the superior tarsal muscle (Muller's muscle); it provides a further 2 mm elevation of the eyelid and is sympathetically innervated. The tarsal plates consist of dense connective tissue and give support and strength …