Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

11.Hypotony may be present.

12.Enophthalmos

13.There is rise of skin temperature of the ipsilateral lid and face.

14.Brittle and dry hair

Diagnosis

Diagnosis is easy. A case of unilateral mild ptosis, miosis, enophthalmos with normal extraocular muscles, preserved light and near reflex is diagnostic.

Diagnosis is confirmed, specially the site of lesion by pharmacological tests.

1.Cocaine test. The test confirms sympathetic denervation. Normal pupil will dilate with 4%-10% cocaine when instilled in the eye in about 30 minutes to 45 minutes. One drop of 4-10% cocaine is instilled in each eye. The drop is repeated after one minute and size of the pupil is noted after 30 to 45 minutes. In a positive test the affected pupil either does not dilate or dilates poorly irrespective of level of lesion.

2.Paredrine (Hydroxy amphetamine) - One percent paredrine will dilate the pupil only in pre ganglionic lesion and not in post ganglionic lesion.

3.Adrenaline test - Adrenaline 1:1000 is instilled in both eyes.

(a) In normal eyes, pupil will not dilate.

(b) In pre ganglionic lesion both pupil will not dilate.

(c) Horner’s pupil will dilate with 1:1000 adrenaline. Phenylepherine in 1% drop does not dilate normal pupil but will dilate a pupil in post ganglionic Horner’s syndrome.

In children, common causes of Horner’s syndrome are—birth trauma due to stretching of brachial plexus, mediastinal and neck neuroblastoma. Surgical or accidental trauma to mediastinum or neck may also cause the defect.

Horner’s syndrome may be associated with cluster headache i.e. Raeder’s para-trigeminal syndrome.

REFERENCES

1.Duke Elder S. : Polycoria in System of Ophthalmology. Vol. III, Part II, pp. 592-596, Henry Kimpton, London, 1964.

2.Glasser J.S. : Essential anisocoria in Neurophthalmology. pp. 174 : Harper and Row, London, 1978.

3.Brain W. Russel : The pupil and the eye lids in Diseases of nervous system. Sixth edition, pp. 71-75, Oxford University Press, London, 1962.

4.Kanski J.J. : Abnormalities of the pupil in Clinical Ophthalmology. Second edition, pp. 472-475, Butterworth, London, 1989.

5.Seal S.K. : Pupillary pathways and reflexes in G.N. Seals Textbook of Ophthalmology. Fifth edition, pp. 21-25, Current Book International, Kolkata, 2002.

6.Rosenberg M.A. : The pupil physiology and anatomy in Principles and practice of ophthalmology. Vol. III, First Indian edition, pp. 1943-1951, Edited by Peyman G.A., Sander D.R. and Goldberg M.F. Jay Pee Brothers, New Delhi, 1987.

7.Natchair G. Subhuram P. : Normal and abnormal pupils in Modern Ophthalmology. Vol. 2, Second edition, pp. 941-944, Jay Pee Brothers, New Delhi, 2000.

8.Duke Elder S. : Autonomic effectors in System of Ophthalmology. Vol. VII, pp. 535585, Henry Kimpton, London, 1962.

9.Garg A. : Mydriatics and cycloplegics in Textbook of ocular therapy. First edition, pp. 139-146, Jay Pee Brothers, New Delhi, 2001.

10.Garg A. : Miotics in Textbook of ocular therapy. First edition, pp. 78-85. Jay Pee Brothers, New Delhi, 2001.

11.Samant P.M., Hemalini Samant and Nabar S.M. : Abnormal pupillary reaction in

Ophthalmology theory and practice. First edition, pp. 313-316. Bhalani Publishing House, Bombay, 2004.

12.Harley R.D. : Pretectal pupillary defects in Pediatric ophthalmology. Vol. II, Second edition, pp. 785-787, WB Saunders Company, Philadelphia, 1983.

13.Shirley H. Wray : Argyll Robertson pupil in Manual of ocular diagnosis and therapy. Third edition, pp. 357, Edited by Devorah Pavan Langston, Lippincot Williams and Wilkins, Philadelphia, 1991.

14.Dutta L.C. : Argyll Robertson pupil in Ophthalmology principle and practice. First edition, pp. 404. Current Book International, Calcutta, 1995.

15.Kanski J.J., Thomas D.J. and Holmes ; Adies pupil in The eye in systemic disease. Second edition, pp. 64, Butterworth - Heinnemann, London.

16.Laties A.M. : Horner’s syndrome in Textbook of Ophthalmology. Ninth edition, pp. 516, Edited by Scheic H.G. and Albert D.M., WB Saunders Company, Philadelphia, 1977.

17.Gittinger J.W. : Horner’s syndrome in Manual of clinical problems in Ophthalmology. First edition, pp. 190-192, edited by Gittinger J.W. and Asdourian G.K. Little Brown and Company, Boston, 1998.

structure. Through the gaps of sieve pass the bundles of optic nerve fibres. The lamina is slightly curved backwards.

The optic nerve anterior to the lamina cribrosa in non-myelinated. Myelation begins behind the lamina. The optic nerve is the last nerve in the body to be myelinated.3

Intraorbital part. The intra orbital part of the optic nerve is the longest part of the optic nerve. It extends from back of the globe to the anterior end of the optic canal. The optic nerve is not a straight structure, it has a downward bend in the anterior part and a medial bend in the posterior part. This curve prevents the optic nerve from being stretched. It becomes straight in extreme lateral gaze and proptosis.

The intra orbital part lies in the centre of the muscle cone surrounded by the orbital fat. It is covered throughout, its intra orbital cover by dura, arachnoid and pia. These coverings are continuous with meninges of the brain. The dura is the outermost and the pia is the innermost layer. The dura is continuation of intra cranial dura that passes through the optic canal and on reaching the orbit divides into two, the outer becomes periorbita while the inner continues to travel on the optic nerve up to back of the sclera where it merges with the outer surface of the sclera.

The arachnoid lies deeper to the dura. In between lies the sub dural space, unlike brain the sub dural space of the optic nerve is only a potential space. The arachnoid also blends with the sclera. The space between the arachnoid and the pia ends blindly at the posterior part of the sclera but continues intra cranially. The space is filled with cerebro spinal fluid. The central retinal artery and central retinal vein passes through the sub arachnoid space from beneath to get into the optic nerve, 10-12 mm behind the globe. During its course through the sub-arachnoid space, the vein may be pressed by the increased CSF pressure, resulting into edema of the disc.

At the apex of the orbit, the nerve is surrounded by annulus of Zinn from which the four recti originate. The superior and medial recti at their origin are closely attached to the dural sheath of the optic nerve. Stretching of this attachment when the eye is moved causes pain in inflammation of the optic nerve.

The ciliary ganglion lies lateral to the nerve almost in the middle of muscle cone. The lower division of oculomotor, the abducent, the nasociliary nerve, the sympathetic fibres and sometimes the ophthalmic veins lie between the nerve and the lateral rectus.

The nerve is surrounded by the long ciliary nerves, short ciliary nerves and posterior ciliary arteries at the back of the sclera.

Most posteriorly the nerve is crossed above by the ophthalmic artery.

The intra canalicular part. This part is about 1 cm in length and is the immobile part of the nerve. It is well protected in the bony canal. The canal not only transmits optic nerve but also its meninges, ophthalmic artery, the sympathetic fibres.

The ophthalmic artery has a close relation with the optic nerve. The ophthalmic artery crosses the nerve inferiorly in the dural sheath. The sphenoidal and posterior ethmoidal sinuses lie medial to the optic nerve in the canal. The nerve is separated from the sinuses by very thin bone, hence infection of the sinuses can infect the nerve with ease.

The intra cranial part. The intra cranial part of optic nerve lies in the middle cranial fossa. It extends from the posterior end of the optic canal to the anteriolateral angle of optic chiasma. It measures about 1 cm. It is a flattened band, spear shaped in section with apex laterally.

The dura and arachnoid that covers the optic nerve from back of the globe to the end of the optic canal stop short at the back of the optic canal. The intra cranial part is covered by pia only.

The intra cranial part of optic nerve first lies on the diaphragma sella and then on the anterior part of the cavernous sinus. The internal carotid lies atfirst below the nerve and than lateral to the nerve. The opthalmic artery originates from the internal carotid under the nerve in the middle of the nerve.

Blood supply of the optic nerve :

The blood supply of the optic nerve is divided into supply to :

1.Optic nerve head

2.Intra orbital

3.Intra canalicular and

4.Intra cranial

The main blood supply of the optic nerve is derived from :

1.Internal carotid via its branches

2.Anterior cerebral artery

Blood supply to the optic nerve head is most important in relation to glaucoma.

Blood supply to the optic nerve head5, 6. Blood supply of the optic nerve is derived from two sources—(1) Retinal, (2) Ciliary.

For description, blood supply of optic nerve head is divided into following groups :

1.Blood supply to the surface nerve fibres.

2.Blood supply to pre laminar and laminar region.

3.Blood supply to retro laminar area.

The surface of the optic nerve gets its blood supply from branches of central retinal artery that anastomose with branches of the prelaminar area.

The prelaminar and laminar area get blood supply from short posterior ciliary ar-

tery.

The retro lamilar area gets its blood supply from both retinal and ciliary circulation.

Development of Optic Nerve7, 8

The optic stalk is the precursor of the optic nerve. It joins the eye and the forebrain. The embryonic fissure that develops at the lower side of the optic cup also extends into the optic stalk. The optic stalk elongates with a groove at its underside. By the end of six weeks axons from the optic cup (retina) gets into the optic stalk (nerve). At the same time the hyaloid artery also enters the optic nerve. The axons surround the hyaloid artery.

By third month of gestation small capillaries develop in the nerve. The coverings of the optic nerve i.e. the pia, arachnoid and dura become well defined by seventh month.

The lamina cribrosa develops partly from the choroid and partly from the sclera.

As the axons of the ganglion cells grow in the optic nerve, some retinal cells get cut off from the main body and get separated as a small clump of glial tissue. This clump of glial tissue forms the early optic nerve head. At birth the raised area atrophies to form the optic cup.

Optic nerve is myelinated very late. Myelination of the optic nerve actually starts in the lateral geneculate body9 and spread towards the eye. By birth the myelination is complete and stops generally behind the lamina.

Congenital Anomalies of Optic Nerve

Congenital anomalies of optic disc are common10. They may vary from complete absence to megalo papilla11 both of which are very rare. The congenital anomalies of optic nerve are rarely confined to the optic nerve itself. It is generally associated with developmental anomalies of retina, uvea, central nervous system and mid facial defects.

They are caused mostly due to defect in

1.Closure of embryonal fissure.

2.Failure of axons to reach the optic stalk.

3.Failure of hyaloid system to atrophy.

4.Midline facial defects.

The common congenital anomalies can be clinically divided into

1.Opaque nerve fibre

2.Abnormality of hyaloid system

3.Coloboma —Total

—Partial

—Pits

—Morning glory syndrome.

4.Dysplasia

5.Dysversion

6.Pseudo papilledema (pseudo neuritis)12

Common symptoms of congenital anomalies of optic nerves are :

1.Diminished vision ranging from loss of few lines on Snellen’s chart to total absence of vision.

2.Sluggish or absent pupillary reaction.

3.Diminished colour sense.

4.Field defect.

5.Associated symptoms of error of refraction, squint, amblyopia, and nystagmus.

Importance of correct diagnosis of congenital anomalies of optic nerve lies in the fact that they may masquerade as optic neuritis or papilledema and the child may be subjected to unnecessary investigations.

Myelinated nerve fibres (opaque nerve fibre). This is most probably the commonest congenital anomaly of the disc and the retina. Generally myelination of the anterior visual path begins in the lateral geniculate body and progresses towards the optic nerve head. The myelination starts late in the intra uterine period (seventh month). The myelination stops short at the lamina. However due to some unknown causes in some infants, the myelination extends well beyond the disc and spreads over the axons of ganglion. The myelination is not equally distributed on the retina. It is generally seen in patches extending from the disc towards the retinal periphery in leaf like pattern. On rare occasions it may spread all round the disc. Less frequently the opaque nerve may develop away from the disc as isolated patch.

The condition may be bilateral but need not be symmetrical. It is more common among the boys. It is not present at birth. It takes about a month to be visible in a new born. Hence it may be considered as a developmental anomaly13 of the retina.

Symptoms. The symptoms depend on involvement of retina and macula. Patches near the disc do not cause any visual symptoms. Loss of vision occurs only when the macula is involved.

Signs. There are no external signs of myelinated (medulated) nerve fibres. However large patches may give a gray reflex on retinoscopy. The condition is diagnosed following ophthalmoscopy.

The ophthalmoscopic picture is characteristic and diagnostic. The picture consists of white, fluffy, irregular patches extending from disc towards the retinal periphery. The patches are frayed and feathered. The large vessels pass over the white patch on the periphery but near the disc they are entirely or partially covered by the medulated fibres. Rarely the medulated fibres may obscure the disc itself. Generally the macula is spared. It may be surrounded by two arches of opaque nerve fibres one above and the other below.

The medulated fibres do not transmit light hence they produce scotomas. The scotomas as they are gradual to develop, are negative in nature. The scotomas may cause enlargement of the blind spot either locally or all round the disc depending upon the spread of the myelination. The enlarged blind spot may be joined by arcuate nerve fibre defect or there may be isolated scotoma away from the disc corresponding to peripheral patches.

The myelination are permanent feature. only occasions when they have been seen to disappear are following optic atrophy, due to demyelination or ischaemia.10

There are no complications known to be caused by myelinated nerve fibres and the condition does not require any treatment.

Congenital crescent (conus) of the optic disc. This condition is also a common ophthalmoscopic finding. The condition presents as a semi lunar white area adjacent to the optic nerve. The maximum length of the crescent is parallel to the long axis of the disc, which is invariably oval. The condition is present at birth, does not change its shape or size with age. Cup of the disc is nearer the crescent. The edge of the disc away from the crescent is

raised. The condition is generally associated with error of refraction which is astigmatic in nature, both myopia or hypermetropia are common. The cause of astigmatism is due to associated change in corneal curvature. The crescent may cause nerve fibre defect in the corresponding area.

The exact mode of formation of crescent is not well understood. Some think it to be a modified coloboma of the optic nerve head. Hence this is also known as Fuch’s coloboma. The other theory is that it is a fault in mesodermal development of the eye.

The condition itself is symptomless but the child is brought with diminished vision, which is a commonly associated with feature due to error of refraction.

The treatment is correction of error of refraction.

Congenital Coloboma of the Disc

Congenital coloboma of the disc may be localised to the disc itself or may be associated with uveo retinal coloboma. The cause of both the forms is faulty closure of the embryonal fissure, hence the coloboma is situated in the lower part of the disc. The coloboma when associated with coloboma of choroid and retina may be extensive enough to spread from pupillary margin to the optic nerve head. In severe form the retina and choroid may herniate through the embryonal fissure below resulting in to congenital cystic eyeball. In less extensive case a chink of uveo-retinal fissure may divide the coloboma in two parts resulting into a bridge coloboma. This must be differentiated from duplication of optic nerve head that is extremely rare. In case of congenital coloboma the scleral canal is wider than normal and the nerve fibres are generally atrophic, the blood vessels are normal.

The symptoms of coloboma localised to disc itself is generally superior nerve fibre defect only. The coloboma associated with retinouveal coloboma is always associated with gross visual loss and field defect.

The coloboma of the disc should be differentiated from glaucomatous cup.

There is no specific treatment. The associated error of refraction should be corrected to give best possible vision.

Morning glory syndrome10, 14, 15. Morning glory syndrome is a rare unilateral congenital condition. It is perhaps a colobomatous disorder. The optic nerve head is enlarged, pale and excavated. The base of the cup contains remnants of hyaloid system. The blood vessels instead of arising from the centre of the disc arise from the rim in spoke of wheel pattern. The disc is surrounded by rim of chorioretinal tissue that is elevated. This is surrounded by a pale zone all round. The appearance resembles the flower morning glory after which the syndrome is named. The condition is associated with non rhegmatogenous retinal detachment. The large lesion may give a gray reflex on, retinoscopy and the condition may be confused as leucocoria that is excluded by examination with indirect ophthalmoscopy and ultra sonography. There is no known treatment.

Congenital pit of the optic nerve. This condition was considered a rarity. It is proving to be more common than expected. The incidence is as high as 1 in 10,000 live births16. The

condition is generally unilateral but in one fifth instances it can be bilateral. The exact cause of the condition is not known but fault in closure of embryonal fissure is most widely accepted theory.

The pits are present in childhood but symptoms develop in second or third decade. It is equally common among boys and girls. It may be present in siblings who may or may not be symptomatic.

The symptoms vary from no symptoms to severe loss of vision, metamorphopsia. On examination the effected disc is generally larger than the unaffected. The pits are more prominent than the holes in lamina. The number, shape, size and position of the pits vary from eye to eye. There may be one pit or may be multiple pits. The shape may be circular dot like, slit like or triangular. The pit is mostly seen in inferio temporal quadrant. Pits situated on temporal side produce more symptoms than on the central part. The pit may be pigmented occasionally.

The cause of diminished vision is macular involvement. The macular lesion is serous detachment of sensory retina. The lesion looks similar to central serous retinopathy and is often mistaken as such. The commonest shape of the macular lesion is tear drop raised area with apex towards the disc, rarely the lesion may be circular. There may be a gray membrane on the floor of the disc. The field changes are common. They are - Enlargement of blind spot, central or paracentral scotoma and arcuate scotoma. The central scotoma may be absolute or relative. The eyes are externally normal.

In all cases of central serous retinopathy, the disc should be carefully examined by direct ophthalmoscope or +90D lens. The spread of the lesion is best seen on indirect ophthalmoscopy.

The detachment of the sensory retina may be : (1) Self limiting, (2) There may be permanent loss of vision due to scarring and subretinal neovascularisation.

The nature and source of sub retinal fluid is controversial, three possible sources are :

(1)CSF

(2)Vitreous and

(3)Leak from the capillaries.10

As the exact etiology and natural history of the disease is not well understood, there is no specific treatment. Laser photo coagulation of the leaking vessels is most logical treatment but the result have not been uniform.

The differential diagnosis consists of :

1.Central serous retinopathy

2.Small coloboma of the disc.

3.Traumatic maculopathy

4.Subretinal neovascularisation.

Hypoplasia of the optic disc10, 12, 17

This is again one of the congenital anomalies that was thought to be rare but the prevalence is more than previous estimates.

The effected nerve is smaller than usual. It is almost one third of the average size. The colour vary from pink to pale white. The retinal vessels are of normal size and distribution. The hypoplastic disc is surrounded by a halo of hypo-pigmentation of retina and choroid. The condition is bilateral in sixty percent of children.

The symptoms are mostly visual and cause of subnormal vision.

Vision may be normal or slightly reduced and mistaken for amblyopia and child subjected to anti amblyopia treatment. However in severe form of hypoplasia the vision may be reduced severely.

In presence of severe loss of vision, there is generally an afferent pupillary defect. Many a times the children are brought with squint and nystagmus.

The hypoplastic optic disc may be seen as an isolated defect in otherwise normal eye or the eye may have associated aniridia, nystagmus, absent foveal reflex.

The optical canal is narrower on the involved side. This is a good diagnostic feature in unilateral cases where the small optic foramen and canal can be compared with the normal side.

The condition may be associated with mild to severe deformity of the central nervous system, which are more common in bilateral cases. There may be deformity of ventricle, such patients have short stature and low level of growth hormone.

The exact cause of hypoplasia of optic disc is not understood. The commonest theory advanced is primary failure of retinal ganglion cells and nerve fibres in otherwise normal retina18. An absence of axons in the nerve reduce the size of the disc.

There is no specific treatment. Children with bilateral cases may have to be treated as visually challenged children.

Bergmeister’s Papilla

The normal lens during its development gets nutrition from the hyaloid artery that extends from the optic disc, passes through the vitreous and reaches the lens. It normally regresses during the development of the eye and should disappear at birth. However in some children it may be seen in patches in the anterio posterior axis of the eye.

When the posteriormost part fails to regress, the condition is called Bergmeister’s papilla. The papilla is in fact, is a central core of vascular tissue surrounded by fibroglial tissue.

Sometimes there may only be fibroglial tissue that looks like a translucent membrane over the disc or may project in the vitreous.

The condition does not cause any symptoms. No complications are known to arise from it, hence, the condition does not require any treatment.

Drusen of Optic Nerve

Drusen is not a congenital anomaly in true sense as it is not detectable clinically at birth. It is better called a developmental anomaly. There is no structural change in the tissue