Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

If the patient fails to show desired therapeutic dose, oral steroid are started, initially a single daily dose is given till the desired effect has been reached, then the schedule is changed to every alternate day and gradually reduced.

Other drug used in patient is refractory to anticholine esterase drugs is azathioprine. It takes few months to be effective. Greatest drawback with the drug is its hemato and hepato toxicity.

Cyclosporine and cyclophosphamide are other immunosuppressive drugs used in selected cases.17

Ancillary ocular methods

1.The child learns by experience to close one eye to avoid diplopia. The eye may be patched to give same effect.

2.Prisms may be given to minimize diplopia. As diplopia is fleeting and changes direction too often many a times prisms may be of little use.

3.Ptosis crutches have limited value.

Thymectomy have been claimed to give good result in refractory cases in selected few.

Chronic progressive external ophthalmoplegia25

The condition may be seen in children as well as adults. Generally it manifests between second and fourth decade. It is a bilateral disease of slow progress. It is associated with mutation in mitochondrial DNA.24A In fifty percent of cases the disease is hereditary.

The first sign that develops after ten years of age is gradually developing ptosis, which progresses to become complete. The ptosis is bilateral and symmetrical. Ophthalmoplegia develops years after ptosis. Involvement of muscles is ill defined. It begins as single muscle involvement resulting in diplopia. As more muscles get involved the eye becomes almost immobile and diplopia disappears. The internal ocular muscles are spared. The child throws the head back to get clearer vision and forehead shows prominent frontal creases.

So long only extraocular muscles are involved, the condition is considered as ocular myopathy. If other muscles get involved it is called ophthalmoplegia plus.

The condition may be associated with retinal pigment degeneration and heart block. Occasionally there may be involvement of pharyngeal muscle.

There is no known specific treatment. Each disorder has to be treated individually.

Evaluation of a case of ptosis for surgery

Definite treatment of congenital ptosis is surgery. It is mandatory to evaluate each patient separately. Sometimes each eye may require individual evaluation. Common heads under which a ptotic child is evaluated are:

1. History. Find out if ptosis is congenital or acquired. In case of acquired ptosis attention should be diverted to find out the primary cause and its management. In case of acquired ptosis surgical intervention should be undertaken only when the ptosis has been stable for at least one year.

Congenital ptosis requires more correction than acquired. However levator resection gives less correction in congenital ptosis.

2. Examination of the eye

1.Vision—Visual acquity is evaluated to diagnosis presence of amblyopia that requires energetic anti amblyopic treatment.

2.Examination of the lids

(i) Exclude pseudo ptosis from true ptosis, however some of the pseudo ptosis may require surgical intervention.

(ii) Presence of epicanthic fold and blepharophimosis which may require separate surgeries.

(iii) Absence of orbicularis action goes more in favour of myasthenia. (iv) Presence of synkinetic movements require multiple surgeries.

(v) Width of inter palpebral fissure gives a rough idea about levator function.

Width of the inter palpebral fissure depends upon

(i) Action of LPS present.

(ii) If the action of LPS is poor, the lid will droop down.

The usual method to assess position of the upper lid is to find out level of the lid margin in relation to upper limbus and comparing this with normal eye. In unilateral ptosis the other eye acts as control.

In normal eye the upper lid covers upper 2 mm of the cornea in primary gaze. The average vertical diameter of cornea is 11 mm. This leaves 9 mm of cornea not covered by lid. If the upper lid droops by 2 mm from usual position i.e. 4 mm from upper limbus leaving on 7 mm of uncovered cornea, the condition is designated as 2 mm ptosis and the ptosis is considered to be mild ptosis. Similarly ptosis of 3 mm is called moderate and more than 4 mm is called severe ptosis.

The choice of type of surgery to be undertaken partly depends upon degree of ptosis i.e. mild, moderate or severe and amount of levator function available.

The function of levator is assessed by noting the excursion of upper lid from downward gaze to maximum up gaze. In normal eye, this is between 12 mm-15 mm. If excrusion is more than 8 mm, it is called good excrusion while fair excrusion means5-7 mm and less than 4 mm is poor. More is the excrusion better is the action of LPS, which means that the levator if strengthened surgically will eliminate ptosis.

3.Presence of Bell’s phenomenon. Bell’s phenomenon is one of the most important defence mechanisms of the eye. It is lost in paralysis of the superior rectus. In absence of Bell’s phenomenon, if the upper lid is raised the cornea becomes unprotected and exposed to external injuries. Absence of Bell’s phenomenon is an absolute contra indication for any type of ptosis surgery.

4.Exclude vertical tropia by cover test. This unmasks presence of pseudo ptosis.

5.Action of extraocular muscles—Under action of extraocular muscles result in diplopia that is generally not felt if the upper lid covers the pupil. In presence of ocular palsy, correction of ptosis will result in intractable diplopia, which may be considered worse than cosmetic ptosis by the patient.

6.Sensation of cornea—Absence of corneal sensation is absolute contra indication for ptosis surgery.

7.Tear film status—Poor tear film status becomes worse following ptosis surgery.

Lid retraction25,26

Normal upper lid covers up to 2 mm of the cornea in primary position and the upper lid follows the movement of the globe both in up and down gaze.

If the upper lid does not reach the upper limbus or is so placed that a strip of sclera is visible above the cornea it is called lid retraction. This is generally associated with lid lag. Exposure of a strip of sclera below the lower limbus may be seen in case of sympathetic over activity along with upper lid retraction. Visible bare sclera above and below is seen in exophthalmos and proptosis.

Lid retraction can be seen in some physiological states also specially in infants and children.

1.In infants: Transient lid retraction is common that pass off within a few weeks. There may be widening of IPA if the illumination in the room is reduced.

2.Children: Children suffering from progressive loss of vision have upper lid retraction as an effort to see better.

Pharmacological causes of lid retraction

1.Phenylepherine: In normal person phenylepherine does not cause any change in lid position in relation to cornea but children with tendency towards sympathetic over action show retraction of 1 mm to 2 mm following local instillation of phenylepherine. The effect passes off with in hours.

2.Prostigmine and tensilon when given as injection cause improvement of ptosis and sometimes the lid may be retracted.

3.Infants born to mothers with hyperthyrodism show retraction for two to three weeks.

4.Prolonged use of steroids are also known to cause lid retraction.26

In unilateral ptosis the contra lateral lid may show retraction when the ipsilateral lid is forced to elevate.

Pathological lid retraction

Lid retraction can either be unilateral or bilateral. In unilateral cases the condition may remain unilateral or the other eye may be involved later. Bilateral lid retraction is generally symmetric.

Commonest cause of lid retraction is dysthyroid myopathy due to sympathetic over action of Muller’s muscle. This is enhanced by instillation of sympathomimetic drugs and reduced by instillation of sympatholytic drugs. Lid retraction is dysthyroid myopathy is generally bilateral and symmetrical. Other causes of lid retraction are sympathetic over action and dorsal mid brain lesion.

Sympathetic lid retraction presents with feature opposite of sympathetic ptosis. It consists of widening of IPA, enhanced lid crease, dilated pupil, mild exophthalmos, sweating on the affected side and lowered temperature.

Dorsal mid brain lesion is called Collier’s sign that consists of bilateral lid retraction, there is conjugate up gaze paralysis of convergence, dissociation of light near reflex. There may be associated retraction nystagmus.

Lids may be caught in scar of the lid following infection, burn, trauma accidental or surgical. Over correction of ptosis is a common cause of unwanted lid retraction.

Treatment of lid retraction consists of recession of LPS along with Muller’s muscle.

Lagophthalmos

In this condition there is either difficulty in closing the eye or there is complete absence of lid closure. Closure of lids is brought about by the orbicularis muscle that is supplied by facial nerve. Hence it is but natural that affection of facial nerve will lead to lagophthalmos, the lesion may be anywhere from its nucleus to extreme periphery in the orbit.

Besides neurological causes there are other causes that are generally put under mechanical causes that prevent the lids to close.

These are—

—Large coloboma of the upper lid.

—Scar on the skin surface of the lids.

—Extreme degree of symblepharon.

—Ectropion

—Proptosis

—Exophthalmos

—Over correction of ptosis

Myasthenia is the main myogenic cause of lagophthalmos

In Mobius syndrome there is bilateral facial palsy with bilateral sixth nerve palsy due to aplasia of their nuclei.

Nocturnal lagophthalmos is a mild form of bilateral lagophthalmos, which becomes obvious when the child sleeps. A strip of the IPA remains open during sleep. On examination there is mild weakness of orbicularis. Bell’s phenomenon is intact.

Lagophthalmos is generally unilateral due to peripheral involvement of seventh nerve, i.e. Bell’s palsy or trauma.

Bilateral exophthalmos is mostly central in origin. An exception being leprosy which is the foremost cause of bilateral lagophthalmos in adults due to peripheral involvement. Children do not suffer from lagophthalmos due to leprosy.

Other causes of bilateral lagophthalmos (facial diplegia) are— Causes of bilateral lagophthalmos have to be central. They are—

—Mobius syndrome30

—Melkerrson Rosenthal syndrome28,29

—Brain stem trauma30

—Brain stem glioma30

—Lyme disease31

—Guillain Barre syndrome

—Closed head injury

—Myasthenia

Neurological causes of unilateral lagophthalmos—

—Supra nuclear and nuclear lesions does not involve orbicularis in a peripheral lesion.

—A lesion at the pons involves sixth nerve nucleus causing ipsilateral lateral rectus palsy, loss of conjugate gaze toward the same side and hemiplegia of the contra lateral side i.e. Foville’s syndrome.

The same lesion with intact conjugate movement is called Millard-Gubler syndrome.

In children above lesions are due to pontine glioma or degeneration at the level of pons and not vescular as in adults.

A basal lesion involving roots of seventh nerve also affects eighth nerve causing loss of hearing, loss of taste in anterior two third of the tongue and diminished tearing. Common causes for such lesions are fracture base of the skull and basal meningitis.

Cerebropontine angle lesions causesipsilateral facial weakness andhyperacusia.

Geniculate ganglion lesion causes Ramsay Hunt syndrome. Commonest cause of which is herpes zoster where vescicles develop in external auditory canal and tympanic membrane. Other lesions being same as lesion of cerebropontine angle tumour.

Commonest type of facial palsy in all ages is Bell’s palsy.

Bell’s palsy is an acute unilateral facial palsy involving the facial nerve in the facial canal. The lesion causes swelling of the nerve in a narrow canal. Commonsest cause is viral infection though auto immune causes can not be excluded. The symptoms consist of inability to close the eye on the affected side and watering. This may be preceded by pain in ear and over the mastoid with hyperacusis.

The condition is self limiting clearing in two to three weeks without any residual effect. It is known to recur in 3% to 10% cases rarely on the same side, however there may be some cases where there is not complete recovery. Such cases should be investigated for causes other than viral infection.

The signs of Bell’s palsy:

1.Lagophthalmos - The inter palpebral fissure is wide, there is paralytic ectropion of lower lid with watering from the eye.

2.Watering from the eye is partly epiphora due to dribbling of tears over the lid margin and is partly lacrimation due to irritation of unprotected conjunctiva and cornea.

3.The patient is unable to close the eye. In an attempt to close the eye, the eyeball roles up due to intact Bell’s phenomenon.

4.However lower part of the cornea remains exposed in spite of intact Bell’s phenomenon and develops exposure keratitis that may be converted to ulceration on long run.

5.In few days microbial conjunctivitis develops. If Bell’s palsy does not subside, keratonisation of conjunctiva may develop.

6.Corneal sensation and other cranial nerve are normal.

Management of lagophthalmos

The management depends upon the cause of lagophthalmos.

It can be divided into:

1.Management of Bell’s palsy

2.Management of anatomical defects

3.Management of central causes.

Bell’s palsy does not require any specific treatment as it is self limiting. However associated conjunctivitis, keratitis and lagophthalmos requires attention. Conjunctivitis and keratitis are treated with frequent antobiotic drops and lubricants by day and antibiotic ointment by night. If lagophthalmos does not improve with in a fortnight temporary lateral tarsorrhaphy may be required.

Anatomical defects like scars and coloboma are treated by appropriate oculoplastic surgery. The central causes require more elaborate investigation like CT and MRI and treatment is directed towards primary cause.

Melkerrson Rosenthal syndrome28,29 consist of peripheral facial diplegia, puffiness of face and lingua plicata. It manifests in childhood. Lingua plicata is most probably congenital in origin.

Mobius syndrome—This is a multiple cranial nerve palsy of congenital origin, nerves from fifth to twelfth are known to be affected. Commonest combination is sixth nerve with facial diplegia. The child has unilateral or bilateral esotropia. There is inability to abduct the eyes.

REFERENCES

1.Lois J. Martyn : Abnormalities of lid function in Pediatric ophthalmology. Vol. 2, Second edition, p. 807-814. Edited by Harley R.D., WB Saunders Company, Philadelphia, 1986.

2.Duke Elder S. : Congenital anomalies in mobility of lids in System of ophthalmology. Vol. III, part 2. P. 887-905, Henry Kimpton, London, 1964.

3.Honavar S.G., Naik M.N., Geeta K. Vemuganti, Chandrashekhar G. : Ptosis in clinical practice in ophthalmology. First edition. p. 497-502. Edited be Saxena S., Jay Pee Brothers, New Delhi, 2003.

4.Miller S.J.H. : Congenital ptosis in Parson’s diseases of the eye. Seventeenth edition. p-316, Churchill Livingstone, London, 1984.

5.Kahn N.D. : Ptosis in Current ocular therapy. Fifth edition. p-447-449. Edited by Fraunfelder F.T. and Roy F.H., WB Saunders Company, Philadelphia, 2000.

25.Rosenberg M.A. : Ocular myopathy in Principle and practice of ophthalmology. Vol. III, First Indian edition. p-1965-1967. Edited by Peyman G.A., Sanders D.R. and Goldberg M.F., Jay Pee Brothers, New Delhi, 1987.

26.Glaser J.S. : Lid refraction in Neurophthalmology. p-36-37, Harper and Row, London, 1982.

27.Meyer D.R. : Lid retraction in Current ocular therapy. Fifth edition. p-439-440. Edited by Fraunfelder F.T. and Roy F.H., WB Saunders Company, Philadelphia, 2000.

28.Duke Elder S. : Melkerrson Rosenthal Syndrome in System of ophthalmology. Vol. XIII. p-21. Edited by Duke Elder S. and Macfaul P.A., Henry Kimpton, London, 1974.

29.Mukherjee P.K. and Dongre R.C. : A case of acquired facial diplegia, macular edema and lingua plicata. Ind. Jr. Oph. 21 : 36-39.

30.Bajandas F.J., Kline L.B. : Facial diplegia in Neurophthalmology. Third edition. p-153, Jay Pee Brothers, New Delhi, 1989.

31.Hedges T.R. and Hedge5 T.R. : Bells palsy in Current ocular therapy. Fifth edition. p-205-206. Edited by Fraunfelder F.T. and Roy F.H., WB Saunders Company, Philadelphia, 2000.

into two unequal parts i.e. a larger superior part known asorbital part and a smaller palpebral part by the lateral expansion of aponeurosis of the levatorpalpebral superior and Whitnall ligament. The division is limited to the front part of the gland. In the posterior part the two lobes are indistinguishable. As the orbital part lies behind the orbital septum, it is normally neither visible nor palpable, it has a superior and an interior surface, an anterior and a posterior border and two ends, the lateral and medial. Superiorily, the periostium lies between the gland and the orbital bone; the inferior surface has lateral part of the levator with its extension and lateral rectus under it. The posterior border rests on the orbital fat. The medial end reaches, the levator muscle and the lateral end reaches the lateral rectus. There are about 1012 lacrimal ducts that originate in the orbital part and travel through the palpebral part. Hence, removal of palpebral part alone will produce the effect of total removal as far as tears are concerned.

The palpebral part is about one third of the orbital part2. It lies just above the lateral part of the upper fornix. This part is sometimes visible when the lid is everted and the patient looks down and it may be mistaken as a growth. There are six to eight lacrimal ducts that originate in the lower lobe. The lacrimal ducts from both the lobes open in the conjuctival sac 4 to 5mm above the tarsal plate.

Histologically, the lacrimal gland, it is an exocrine tuboalveolar gland that resembles the salivary gland and share similar pathological process i.e. acute infection, by mumps, measles, chronic inflammation i.e. Mikulicz’s syndrome and growth like adenoma.

Blood Supply

The lacrimal gland is supplied by lacrimal artery and some times by infraorbital part of the maxillary artery. The venous drainage is through the lacrimal vein that travels back in the superior ophthalmic vein4. The lymphatics drain in preauricular and submandibular glands.

The nerve supply to the lacrimal gland is divided broadly in to two parts i.e. afferent and efferent. The former is via lacrimal nerve, which is a branch of, trigeminal. The efferent consist of both sympathetic and parasympathetic nerves. The para sympathetic fibres originate in the lacrimal nucleus in the pons and reach the lacrimal gland in the lacrimal nerve2,4a 4a. The sympathetic fibres reach the lacrimal gland via sheath of carotid through ophthalmic artery. Role of sympathetic nerve in tear production is uncertain. The tear production mostly controlled by parasympathetic4a.

2. The Accessory lacrimal glands. These glands are situated in the conjunctiva. They are very small and contribute small amount of fluid mostly mucin to the tear film. They are :

(a) Goblet cells of conjunctiva,

(b) Krause’s glands in the fornices

(c) Glands of Wolfring near the tarsal plate. (d) Glands of Manz in the bulbar conjunctiva. (e) Glands in the plica and caruncle.

(f) Infra orbital glands.

Development of lacrimal and accessory lacrimal glands

The lacrimal gland is ectodermal in origin and is the only source of epithelial tissue in the orbit that is liable to develop malignant epithelial tumours5. The main lacrimal gland