The condition shown in the picture above represents Unilateral Ptosis.
- Abnormal drooping of the upper eyelid is called ptosis.
- Normally, upper lid covers about upper one-sixth of the cornea, i.e., about 2 mm. Therefore, in ptosis it covers more than 2 mm.
Types and etiology
I. Congenital ptosis
It is associated with congenital weakness (maldevelopment) of the levator palpebrae superioris(LPS). It may occur in the following forms:
- 1. Simple congenital ptosis (not associated with any other anomaly) .
- 2. Congenital ptosis with associated weakness of superior rectus muscle.
- 3. As a part of blepharophimosis syndrome, which comprises congenital ptosis, blepharophimosis, telecanthus and epicanthus inversus .
- 4. Congenital synkinetic ptosis (Marcus Gunn jawwinking ptosis). In this condition there occurs retraction of the ptotic lid with jaw movements i.e., with stimulation of ipsilateral pterygoid muscle.
II. Acquired ptosis
- 1. Neurogenic ptosis. It is caused by innervational defects such as third nerve palsy, Horner’s syndrome, ophthalmoplegic migraine and multiple sclerosis.
- 2. Myogenic ptosis. It occurs due to acquired disorders of the LPS muscle or of the myoneural junction. It may be seen in patients with myasthenia gravis, dystrophia myotonica, ocular
- myopathy, oculo-pharyngeal muscular dystrophy and following trauma to the LPS muscle.
- 3. Aponeurotic ptosis. It develops due to defects of the levator aponeurosis in the presence of a normal functioning muscle. It includes involutional (senile) ptosis, postoperative ptosis (which is rarely observed after cataract and retinal detachment surgery), ptosis due to aponeurotic weakness associated with blepharochalasis, and in traumatic dehiscence or disinsertion of the aponeurosis.
- 4. Mechanical ptosis. It may result due to excessive weight on the upper lid as seen in patients with lid tumours, multiple chalazia and lid oedema. It may also occur due to scarring (cicatricial ptosis)
- as seen in patients with ocular pemphigoid and trachoma.