Anomalies in the position of lid margins .pptx

LID ANOMALIES PPT

1. ANOMALIES IN THE POSITION OF LID MARGINS NAOBA MUTUM M.OPTOM

2. ENTROPION Entropion refers to inward rolling and rotation of the lid margin toward globe. Etiological types 1. Congenital entropion : lt is a rare condition seen since birth. Seen more commonly in lower than upper eyelid. Lower eyelid congenital entropion is caused by improper developmem of the lower lid retractors. Upper eyelid congenital entropion is usually secondary to mechanical effects of microphthalmos.

3. 2. Cicatricial entropion. lt is a common variety usually involving the upper lid. It is caused by cicatricial contraction of the palpebral conjunctiva, with or without associated distortion of the tarsal plate. Common causes arc trachoma, membranous conjuncl'ivitis , chemical burns, pemphigus and Stevens-Johnson syndrome.

4. Fig1. CICATRICIAL ENTROPION.

5. 3. Senile (involutional) entropion : It is common occurrence and affects only the lower lid in elder people . Etiological factors which contribute for its development are : • Horizontal laxity of the lid due to weakening of orbicularis muscle. It can be tested by snap-back test and pinch test. • Vertical lid instability due to weakening or dehiscence of capsulopalpebral fascia (lower lid retractor). • Over-riding of pretarsal orbicularis. Degeneration of palpebral connective tissue separates the orbicularis muscle fibres and thus allows preseptal fibres to over-ride the pretarsal fibres and thus tipping the lid margin inwards.

6. Fig 2. SENILE ENTROPION

7. 4. Mechanical entropion: It occurs due to lack of support provided by the globe to the lids. Therefore, it may occur in patients with phthisis bulbi, enophthalmos and after enucleation or evisceration operation.

8. CLINICAL FEATURES Symptoms occur due to rubbing of cilia against the cornea and conjunctiva and are thus similar to trichiasis. These include foreign body sensation, irritation, lacrimation and photophobia . Signs are as follows : 1. Inturning of lid margins: On examination, lid margin is found inturned . Depending upon the degree of inturning , it can be divided into three grades: • Grade I entropion, only the posterior lid border is in rolled, • Grade II entropion, includes in turning up to the inter-marginal strip, and

9. • Grade Ill entropion, in which the whole lid margin including d1e anterior border is in turned. 2. Signs of causative disease, e.g. scarring of palpebral conjunctiva in cicatricial entropion, and horizontal lid laxity in involutional entropion may be seen. 3. Signs of complications include recurrent corneal abrasions, superficial corneal opacities, corneal vascularization and even corneal ulceration.

10. TREATMENT Congenital entropion may resolve with time without need of any intervention or may require excision of a strip of skin and muscle with plastic reconstruction of the lid crease ( Hotz procedure). 2. Cicatricial entropion. It is treated by a plastic operation, which is based on any of the following basic principles: • Altering the direction of lashes, or • Transplanting the lashes, or • Straightening the distorted tarsus.

11. Surgical techniques employed for correcting cicatricial entropion are as follows : Anterior lamellar resection. It is the simplest operation employed to correct mild degree of entropion. In this operation, an elliptical strip of skin and orbicularis muscle is resected 3 mm away from the lid margin. ii. Tarsal wedge resection. It corrects moderate degree of entropion associated with atrophic tarsus. In this operation, in addition to the elliptical resection of skin and muscle, a wedge of tarsal plate is also removed. iii. Tarsal fracture or Transposition of tarsoconjimctival wedge.(Modified Ketssey's operation): This is indicated to treat mild to moderate amount of cicatricial entropion. It basically involves tarsal fracture and eversion of distal tarsus.

12. A horizontal incision is made along the whole length of sulcus subtarsalis (2-3 mm above the lid margin) involving conjunctiva and tarsal plate. The lower piece of tarsal plate is undermined up to lid margin. Mattress sutures are then passed from the upper cut end of the tarsal plate to emerge on the skin 1 mm above the lid margin. When sutures are lied the entropion is corrected by transposition of tarsoconjunctival wedge iv. Posterior lamellar graft. Indications of this operation include severe entropion with upper eyelid retraction.

13. In this operation, the deficient or keratinized conjunctiva and the scarred and contracted tarsus are replaced by a composite posterior lamellar graft. Tarsus may be replaced by preserved sclera or ear cartilage or hard palate along with conjunctival or mucous membrane graft 3. Involutional (Senile) entropion. Surgical techniques are as below: i . Transverse suture and everting suture. Transverse suture offer temporary cure (up to 18 months) and are thus indicated in very old patients. The transverse sutures are applied through full thickness of the lids to prevent over-riding of the preseptal muscles.

14. Everting sutures tighten the lower lid retractors. These are similar to transverse sutures except that these are passed at lower level in the inferior fornix and emerge out from the skin near the lash line ii. Wies operation (Transverse lid split and everting sutures). This operation is indicated for long term cure in patients with little horizontal laxity. In this operation, an incision involving skin, orbicularis and tarsal plate is given 3 mm below the lid margin, along the whole length of the eyelid. Mattress sutures are then passed through the lower cut end of the tarsus to emerge on the skin, 1 mm below the lid margin and are tied firmly.

15. The entropion is corrected by prevention of over-riding of preseptal muscle by the horizontal fibrous scar tissue barrier and transferring of the pull of lid retractors to the upper border of tarsus by the everting sutures. iii. Plication of lower lid retractors (Jones operation). It is performed in severe cases or when recurrence occurs after the above described operations. In this operation, the lower lid retractors are exposed via horizontal skin incision at the lower border of the tarsal plate, shortened and the sutures are used to create a barrier to prevent over-riding of the preseptal muscle.

16. iv. Quickert procedure. This is indicated in patients having associated marked horizontal lid laxiry . This operation consists of transverse lid split to create barrier for over-riding of preseptal muscle, everting sutures to transfer pull of lower lid retractors to upper border of tarsus and horizontal lid shortening to correct the laxity . Thus, Quickert procedure basically combines horizontal lid shortening with Weis procedure. v. Lateral tarsal strip (LTS), is basically a lateral canthal tightening procedure in which lateral tarsal strip is excised. It is useful in marked lid laxity of lateral tarsal strip.

17. ECTROPION Out rolling or outward turning of the lid margin is called ectropion. Etiological types 1. Congenital ectropion . This is rare entity and is usually associated with other eyelid malformations such as ankyloblepharon , ptosis, epicanthus inversus, Down syndrome and blepharophimosis syndrome. It may occur in both the upper and lower lids and is due to a congenital shortage of the skin.

18. 2. Involutional ectropion . lt is the commonest variety and involves only the lower lids . It occurs due to following age-related changes: • Horizontal laxity of eyelid, • Medial canthal tendon laxity, • Lateral canthal tendon laxity, and • Dehiscence or disinsertion of lower lid retractors.

19. 3. Cicatricial ectropion . It occurs due to scarring of the skin and can involve both the lids. Common causes of skin scarring are: thermal burns, chemical burns, lacerating injuries skin ulcers, scarring skin tumours and medication allergies. 4. Paralytic ectropion . It results due to paralysis of the seventh nerve. lt mainly occurs in the lower lids. Common causes of facial nerve palsy are: Bell's palsy, head injury, infections of the middle ear and operations on parotid gland.

20. 5. Mechanical ectropion : It occurs in conditions where either the lower lid is pulled down (as in tumours ) or pushed out and down (as in proptosis and marked chemosis of the conjunctiva).

21. CLINICAL FEATURES Symptoms • Epiphora is the main symptom in ectropion of the lower lid. • Symptoms due to associated chronic conjunctivitis include: irritation, discomfort and mild photophobia. Signs 1. Lid margin is outrolled . Depending upon the degree of outrolling , ectropion can be divided into three grades: • Grade I: In it only puncnun is evened. • Grade 2: Lid margin is everted and palpebral conjunctiva is visible. • Grade Ill: The fornix is also visible.

22. 2. Signs of the etiological condition such as: • Skin scars in cicatriciaJ ectropion and • Seventh nerve palsy in paralytic ectropion may also be seen. 3. In involutional ectropion one or more of the following signs can be elicited: • Horizontal lid laxity can be demonstrated by positive snap test, i.e. lid can be easily pulled away from the globe but fails to snap back to the normaJ position on release.

23. Medial canthal tendon laxity. Normally on pulling the lid laterally the inferior punctum moves by l-2 mm only; while it can be moved up to limbus in mild and up to pupil in severe degree of medial tendon laxity. • Lateral canthal tendon laxity is evidenced by row1ded appeara.rnce of the lateral canthus and its more than 2 mm movement on pulling the lid medially.

24. Complications • Dryness and thickening of conjunctiva and corneal ulceration (exposure keratitis) may occur due to prolonged exposure. • Eczema and dermatitis of the lower lid skin may occur due to prolonged epiphora.

25. TREATMENT 1. Congenital ectropion. Mild ectropion often requires no treatment. Moderate or severe ectropion is treated like cicatricial ectropion with horizontal lid tightening and full thickness skin graft to vertically lengthen anterior lamella.

26. 2. Involutional ectropion : depending upon the severity, following three operations are commonly performed: Medial conjunctivoplasty: It is useful in mild cases of ectropion involving punclal area. It consists of excising a spindle-shaped piece of conjunctiva and subconjunctival tissue from below the punctal area . ii. Horizontal lid shortening. It is performed by a full thickness pentagonal excision in patients with moderate degree of ectropion .

27. iii. Byron Smith's modified Kuhnt-Szymanowski operation. It is performed for severe degree of ectropion which is more marked over the lateral half of the lid. ln it, a base up pentagonal full thickness excision from the lateral third of the eyelid is: combined with triangular-excision of the skin from the area just lateral to lateral canthus to elevate the lid. iv. Lateral tarsal strip technique is very useful for generalized ectropion associated with horizontal lid laxity.

28. 3. Paralytic ectropion : Paralytic ectropion often resolves spontaneously within 6 months especially when due to Bell's palsy. Therefore, temporary measures are taken initially. Permanent surgical treatment is required only in non-resolving cases. Temporary measures include: • Topical lubricants, • Taping temporal side of eyelid, and • Suture tarsorrhaphy.

29. Permanent measures include: • Horizontal lid tightening with or without middle lamellar buttress such as ear cartilage or • Palpebral sling operation, in which a fascia lata sling is passed in the subcutaneous layer all around the lid margins.

30. 4. Cicatricial ectropion : Depending upon the degree it can be corrected by any of the following plastic operations: V-Y operation. lt is indicated in mild degree ectropion. In it, a V-shaped incision is given, skin is undermined and sutured in a Y-shaped pattern. Z- plasty ( Elschnig's operation). It is useful in mild t:o moderate degree of ectropion. iii. Excision of scar tissue and full thickness skin grafting. It is performed in severe cases. Skin graft may be taken from the upper lid, behind the ear, or inner side of upper arm.

31. 5. Mechanical ectropion. It is corrected by treating the underlying mechanical factor causing ectropion.

32. SYMBLEPHARON Common causes are thermal or chemical burns, membranous conjunctivitis, injuries, conjunctiva) ulcerations, ocular pemphigus and Stevens-Johnson syndrome. ETIOLOGY In this condition, lids become adherent with the eyeball as a result of adhesions between the palpebral and bulbar conjunctiva. It results from healing of the kissing raw surfaces upon the palpebral and bulbar conjunctiva

33. Clinical features of symblepharon are : • Ocular movements become restricted, • Diplopia may be experienced due to restricted ocular motility, • Lagophthalmos, i.e. inability to close the lids may occur due to adhesions. • Cosmetic disfigurement is a common complaint.

34. Types of symblepharon, depending upon the extent of adhesions, are as below: • Anterior symblepharon-adhesions present only in the anterior part • Posterior symblepharon- adhesions present in the fornices . • Total symblepharon-adhesions involving whole of the lid.

35. Complications These include dryness, thickening and keratinisation of conjunctiva due to prolonged exposure and corneal ulceration (exposure keratitis). Treatment 1. Prophylaxis. During the stage of raw surfaces, the adhesions may be prevented by: • Sweeping a glass rod coated with lubricant around the fornices several times a day. • Therapeutic soft contact lens of large size, also helps in preventing the adhesions.

36. 2 . Curative treatment consists of symblepharectomy The raw area created may be covered by: • Mobilising the surrounding conjunctiva in mild cases. • Conjunctiva/or buccal mucosa/ graft is required in severe cases. • Amniotic membrane transplantation (AMT), also gives good results .

37. ANKYLOBLEPHARON It refers to the adhesions between margins of the upper and lower lids. ETIOLOGY Ankyloblepharon may occur as: • Congenital anomaly and • Acquired adhesions after healing of chemical burns, thermal burns, ulcers and traumatic wounds of the lid margins. Clinically ankyloblepharon may be complete or incomplete. It is usually associated with symblepharon.

38. TREATMENT Lids should be separated by excision of adhesions !between the lid margins and kept apart during healing process. When adhesions extend to the angles, epithelial grafts should be given to prevent recurrences.

39. BLEPHAROPHIMOSIS ln this condition, the extent of the palpebral fissure is decreased. It appears contracted at the outer canthus. ETIOLOGY It may be congenital or acquired, due to formation of a vertical skin fold at the lateral ,canthus (epicanthus lateralis) following eczematous contractions. TREATMENT: Usually no treatment is required. In marked cases, canthoplasty operation is performed.

40. LAGOPHTHALMOS This condition is characterised by inability to close the eyelids voluntarily. ETIOLOGY It occurs in patients with paralysis of orbicularis oculi muscle, cicatricial contraction of the lids, symblepharon, severe ectropion, proptosis, foll owing over-resection of the levator muscle for ptosis, and in comatosed patients. Physiologically, some people sleep with their eyes open (nocturnal lagophthalmos).

41. CLINICAL FEATURES It is characterised by incomplete closure of the palpebral aperture associated with features of the causative disease. Complications include conjunctival and corneal xerosis and exposure keratitis. Treatment is as below : 1. Measures to prevent exposure keratitis • Artificial tear drops should be instilled frequently and the open palpebral fissure should be filled with an antibiotic eye ointment during sleep and in comatosed patients. • Soft bandage contact lens may be used to prevent exposure keratitis.

42. • Tarsorrhaphy may be performed to cover the exposed cornea when indicated 2. Measures lo treat the cause of lagophthalmos, wherever possible should be taken. Tarsorrhaphy ln this operation, adhesions are created between a part of the lid margins with the aim to narrow down or almost close the palpebral aperture. It is of two types: temporary and permanent.

43. Temporary tarsorrhaphy Indications. To protect the cornea when seventh nerve palsy is expected to recover. (ii) To assist healing of an indolent corneal ulcer. (iii) To assist in healing of skin-grafts of the lids in the correct position. Surgical technique . This can be carried out as median or paramedian tarsorrhaphy.

44. Incision : For paramedian tarsorrhaphy, about 5 mm long incision site is marked on the corresponding parts of the upper and lower lid margins, 3 mm on either side of the midline. An incision 2 mm deep is made in the grey line on the marked site and the marginal epithelium is then excised taking care not to damage the ciliary line anteriorly and the sharp lidl border posteriorly. ii. Suturing . The raw surfaces thus created on the opposing parts of the lid margins are then sutured with double-armed 6-0 silk sutures passed through a rubber bolster.

45. 2. Permanent tarsorrhaphy Indications. ( i ) Established cases of VII nerve palsy where there is no chance of recovery; and (ii) established cases of neuroparalytic keratitis with severe loss of corneal sensations. Technique . It is performed at the lateral canthus to create permanent adhesions. The eyelids are overlapped after excising a triangular flap of skin and orbicularis from the lower lid and corre sponding triangular tarsoconjunctival flap from the upper lid.

46. BLEPHAROSPASM It refers to the involuntary, sustained and forceful closure of the eyelids. ETIOLOGY Blepharospasm occurs in two forms: 1 . Essential (spontaneous) blepharospasm . It is a rare idiopathic condition involving patients between 45 and 65 years of age. 2. Reflex blepharospasm . It usually occurs due to reflex sensory stimulation through branches of fifth nerve, in conditions such as: phlyctenular keratitis, interstitial keralitis , corneal foreign body, corneal ulcers and iridocyclitis. It is also seen in excessive stiimulation of retina by dazzling light, stimulation of' facial nerve due to central causes and in some hysterical patients.

47. CLINICAL FEATURES • Persistent epiphora may occur due to spasmodic closure of the canaliculi which may lead to eczema of the lower lid. • Oedema of the lids is of frequent occurrence. • Spastic entropion (in elderly people) and spastic ectropion (in children and young adults) may develop in long-standing cases. • Blepharophimosis may result due to contraction of the skin folds following eczema.

48. TREATMENT Treatment of essential blepharospasm : • Botulinum toxin, injected subcutaneously over the orbicularis muscle, blocks the neuromuscular junction and relieves the spasm. • Facial denervation may be required in severe cases. .

49. Treatment of reflex blepharospasm: • Causative disease should be treated to prevent recurrences. • Associated complications should also be treated .

50. 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. Clinic-etiological Types 1. Congenital ptosis Etiology: It is associated with congenital weakness (maldevelopment) of the levaror palpebrae superioris (LPS) muscle.

51. Characteristic features of congenital ptosis are: • Drooping of one or both upper lids more often since birth of variable severity (mild, moderate or severe). • Lid crease is either diminished or absent. • Lid lag on downgaze (i.e. ptotic lid is higher than the normal) due to tethering effect of abnormal LPS muscle. This is in contrast to acquired ptosis in which ptotic lid is lower than the normal in downgaze also. • LPS function may be poor, fair or good depending upon the degree of weakness.

52. Associated features . Based on the absence or presence of other associated features, the congenital ptosis may occur in following forms: l. Simple congenital ptosis (not associated with any other anomaly. 2. Congenital ptosis with associated weakness of superior rectus muscle. 3. Blepharophimosis syndrome, which comprises congenital ptosis, blepharophimosis , telecanthus and epicanthus inversus .

53. 4. Congenital synkinetic ptosis (Marcus Gunn jaw winking ptosis). In this condition, there occurs retraction of the ptotic lid with jaw movements, i.e. with stimulation of ipsilateral pterygoid muscle. The levator palpebrae is also stimulated. It occurs due to trigemino -oculomotor synkinesis (5th and 3rd cranial nerve), i.e. two or more muscles innervated independently by these two cranial nerves have simultaneous or co-ordinated movement.

54. II. Acquired ptosis Depending, upon the cause it can be neurogenic. myogenic, aponeurotic or mechanical, Neurogmic ptosis. myogenic, aponeurotic or mechanical. 1. Neurogenic ptosis. It is caused by innervarional defects such as: • Third nerve palsy • Horner's syndrome, • Ophthalmoplegic migraine, and • Multiple sclerosis

55. Horner's syndrome , occurring due to oculo-sympathetic paresis, is characterised by classic triad of: • Mild ptosis (due to paralysis of Muller's muscles), • Miosis (due to paralysis of dilator pupillae), and • Reduced ipsilateral sweating ( anhydrosis ), • Other features include mild enophthalmos, loss of cilio -spinal reflex, heterochromia, i.e. ipsilateral iris is lighter in color , pupil is slow to dilate, and there occurs slight elevation of the lower eyelid.

56. 2. Acquired 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, oculopharyngeal muscular dystrophy and following trauma to the LPS muscle, thyrotoxicosis, and Lambert-Eaton myasthenia syndrome.

57. 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 some times observed after cataract and retinal detachment surgery), • Ptosis due to aponeurotic weakness associated with blepharochalasis , and • Traumatic dehiscence or disinsertion of the aponeurosis

58. 4. Mechanical ptosis. lt 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.

59. CLINICAL EVALUATION Following scheme may be adopted for work up of a ptosis patient: 1.History It should include age of onset, family history, history of trauma, eye surgery and variability in degree of the ptosis. 2. Examination Exclude pseudoptosis (simulated ptosis) on inspection. Its' common causes are: • lpsilateral conditions such a microphthalmos, phthisis bulbi, enophthalmos, prosthesis, brow ptosis, dermatochalasis, and hypotropia.

60. • Contralateral conditions include: eyelid retraction, high myopia, and proptosis . B. Observe the following points in each case: • Whether ptosis is unilateral or bilateral. Causes of bilateral ptosis include congenital ptosis, myasthenia gravis, myotonic dystrophy, Kearns Sayre syndrome, Lambert-Eaton myasthenic syndrome, and chronic progressive external ophthalmoplegia. • Function of orbicularis oculi muscle. • Eyelid crease is present or absent.

61. • Jaw-winking phenomenon is present or not. • Associated weakness of any extraocular muscle. • Bell's phenomenon (up and out rolling of the eyeball during forceful closure) is present or absent. 3. Measurement of amount ( degree) of ptosis. • In unilateral cases, difference between the vertical height of the palpebral fissures of the two sides indicates the degree of ptosis • In bilateral cases it can be determined by measuring die amount of cornea covered by the upper lid and then subtracting 2mm.

62. Ptosis is graded depending upon its amount as: • Mild ptosis : 2 mm • Moderate ptosis : 3 mm • Severe ptosis : 4 mm 4. Margin reflex distance (MRD ) Refers to the distance between the upper lid margins and corneal light reflex (of a pen torch held in front, on which patient is looking). Normal value of MRD is 4-5 mm.

63. 5. Assessment of levator function. It is determined by the lid excursion caused by LPS muscle (Burke's method). Patient is asked to look down, and thumb of one hand is placed firmly against the eyebrow of the patient (to block the action of frontalis muscle) by the examiner. Then the patient is asked to look up and the amount of upper lid excursion is measured with a ruler held in the other hand by the examiner. Levator Function is graded as follows: • Normal: 15mm • Good: 8mm or above • Fair: 5 – 7mm • Poor: 4mm or less

64. 6. Special investigations. Those required in patients with acquired ptosis are as follows: i . Tensilon test is performed when myasthenia is suspected. There occurs improvement of ptosis with intravenous injection of edrophonium ( Tensilon ) in myasthenia. ii. Phenylephrine test is carried out in patients suspected of Horner's syndrome. iii. Neurological investigations may be required to find out the cause in patient with neurogenic ptosis.

65. 7. Photographic record of the patient should be maintained for comparison. Photographs should be taken in primary position as well as in up and down gazes .

66. TREATMENT Treatment of Congenital ptosis lt almost always needs surgical correction. In severe ptosis, surgery should be performed at the earliest to prevent stimulus deprivation amblyopia. However, in mild and moderate ptosis, surgery should be delayed until the age of 3-4 years, when accurate measurements are possible. Congenital ptosis can be treated by any of the following operations 1. Tarso-conjunctivo-Mullerectomy ( Fasanella-Servat operation). It is performed in cases having mild ptosis (1.5-2 mm) and good levator function. In it, upper lid is everted and the upper tarsal border along with its attached Muller's muscle and conjunctiva are resected.

67. 2. Levator resection. It is a very commonly performed operation for moderate and severe grades of ptosis. It is contraindicated in patients having severe ptosis with poor levator function. Amount of levator resection required: Most of the surgeons find it out by adjusting the lid margin in relation to cornea during operation on the table in individual case. However, a rough estimate in different grades of ptosis can be made: •Moderate ptosis. Depending on the level of LPS function the amount of LPS to be resected is as below:

68. • Good function: 16 – 17 mm (minimal) • Fair function : 18 – 22 mm (moderate) • Poor function : 23 – 24 mm (maximum) • Severe ptosis. Fair levator function: 23-24 mm (maximum LPS resection).

69. II. Treatment of acquired ptosis • Treat the underlying cause wherever possible. • Conservative treatment should be carried out and surgery deferred at least for 6 months in neurogenic ptosis. • Surgical procedures (when required) for acquired ptosis are essentially the same as described for congenital ptosis. However, the amount of levator resection required is always less than the congenital ptosis of the same degree. • For Horner's syndrome: Fasanella Servat operation. • For neurogenic ptosis in 3rd nerve palsy: Frontalis sling operation.

70. LID RETRACTION Normally, the upper eyelid covers I/6th of the cornea (about 2 mm). Lid retraction is labelled when the lid margin is either at or above the level of supetior limbus. Causes of lid retraction are as below: 1. Congenital. The lid retraction may occur isolated or in association with Duane's retraction syndrome and Down's syndrome. 2. Thyroid eye disease is the more common cause. 3. Mechanical causes of lid retraction are: • Surgical overcorrection of ptosis, and • Scarring of the upper eyelid skin after burns, trauma or infection.

71. 4. Neurogenic causes include: • Facial palsy (due to unopposed levator action), • Third nerve misdirection, • Marcus-Gunn jaw winking syndrome • Parinaud syndrome, and • Effect of sympathomimetic eye drops 5. Systemic causes: • Uraemia .

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