Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

of the optic nerve. Exact cause of drusen is not known, it is said to be due to excess of neurolgia that undergoes degeneration and calcification.12 The drusens contain calcium, mucopolysaccharides, carbohydrate and iron.19

There is strong heredity. It is inherited as autosomal dominant trait. The drusen may be seen in siblings and parents. This feature is so constant that in all cases of suspected drusen in the eye of a child, fundus of his parents and siblings should be examined. If they have fundus picture suggestive of drusen the child may be spared of costly investigations for papilledema.

Drusen is bilateral in 75% of cases. It is equally seen in boys and girls. It is rarely detectable in first decade. They become well established in second and third decade. In advanced case the drusen may be visible as an irregular growth over the disc.

About 0.3% of children have drusen but they go undetected because drusen by itself does not cause any visual symptoms. Presence of drusen comes to light on routine examination for causes other than ocular. Mostly the children are referred as cases of papilledema.

To begin with drusens are deep in the optic nerve head, always anterior to lamina and not visible by direct ophthalmoscope. Examination by Hruby or other suitable lens may give away their presence. Number of drusen may vary from solitary to multiple, when more than one, they may join to form a larger mass.

Ophthalmoscopic finding of drusen are :

1.The colour of the disc is pinkish pale but not hyperemic.

2.Blood vessels on the disc have abnormal branching.

3.Spontaneous vernous pulsation is present in 80% of the eye.

4.The optic cup is shallow to begin with, gradually it fills up and after years, the surface of the disc may be beyond the plane of retina, which is normal.

5.The veins are not dilated and can be traced to the centre of the disc.

6.On fluorescein angiography there is no leak. The drusen shows auto florescence.

7.Ultrasonography is helpful as drusens are good reflector of ultrasound wave even at low decibel.

8.CT of optic nerve head may show buried drusen.

Field changes. Depending upon the position of the drusen in relation to retinal fibres, the field changes can be—enlargement of the blind spot, arcuate or nerve fibre defect. Constriction of lower nasal field is most characteristic.18

Differential diagnosis. Other causes of elevated disc in children i.e. papilledema, neuritis, pseudoneuritis, hamartoma of the disc, Bergemeister papilla.

Complications. The condition is benign, does not cause blindness. However on rare occasion’s there may be haemorrhage in the lesion.

Management. The condition per se does not require any treatment. However child should be kept under observation for few years least the diagnosis of raised intracranial pressure has been missed. This is best done by serial photographs of the disc.

Pseudo neuritis. Pseudo neuritis sometimes mentioned as pseudo papilledema is neither neuritis nor papilledema in true sense. Both of which are acquired. It is better to call it congenital disc swelling. The condition is very common and unless examined carefully, the child is subjected to lots of unnecessary investigation.

The condition is reverse coloboma of the disc where the scleral canal is large and nerve fibres are deficient. In pseudo neuritis the scleral canal is smaller for number of nerve fibres. The condition is ectodermal in origin.

In 80% cases it is bilateral, may be seen in other members of the family.

The condition is common with hypermetropia and hypermetropic astigmatism. However it can be seen in emmetropes as well.

The condition is a asymptomatic. It is generally discovered when children are examined for symptoms of hypermetropia. In such cases the corrected vision remains less normal.

The fundus picture is diagnostic. The disc is small, the margins are indistinct. There is disc swelling that does not exceed +3D. The blood vessels are normal in calibre, and distribution. The retina round the disc is normal, no exudates or haemorrhages are seen. The retina has a peculiar appearance known as shot silk look. There are no field changes. The pupil are normal.

Differential diagnosis consists of all the conditions that cause swelling of the optic disc. They are drusen of optic nerve, remnants of hyaloid system, Bergmeister papilla, neuritis and papillaedema.

Fluorescein angiography differentiate pseudoneuritis from early papillaedema and neu-

ritis.

The condition is non progressive and symptomless, hence it does not require any specific treatment except prescription of glasses for error of refraction when present.

Disorders of Optic Nerve

Disorders of the optic nerve can be—Congenital or acquired.

The acquired cases can be :

1.Infective and/or inflammatory

2.Non infective or non infective.

(a) Papillaedema

(b) Degeneration (c) Dystrophy (d) Traumatic (e) Neoplastic

(f ) Nutritional (g) Vascular

Disorders of optic nerve not only produce visual disturbance that be temporary or permanent but also be indicators of serious systemic disorders that may not only be vision threatening but also fatal.

Symptoms of optic nerve disorder :

1.Visual. Commonest symptom is diminished vision that may range from slight recoverable vision loss to total and permanent loss. However, there may not be any visual loss in the beginning as in papilledema.

2.Amaurosis. Temporary sudden loss of vision (with recovery) is common in papilledema.

3.Colour sense is always affected in disorder of the optic nerve. It is not a total loss of colour vision but the coloured objects look dull especially the red coloured objects.

4.Light brightness is reduced.

5.Field changes. Central and centrocecal field changes are very common in inflammation of optic nerve. In papilledema there is enlargement of blind spot. Peripheral constriction of field is sign of onset of optic atrophy in neuritis and papilledema.

6.Pupillary changes. Afferent pupillary defect is common when the afferent pathway is involved. It is very common in children.

7.Pain on movement of the eyeball is common in acute inflammation of posterior part of the optic nerve.

The disorder of the optic nerve can be present at birth as congenital anomaly or present as developmental anomaly some year after birth or it may be acquired.

The acquired condition can be :

1.Inflammatory and/or infectious

2.Non inflammatory and/or non infectious.

In the first group come papillitis, optic neuritis and retrobulbar neuritis. The second group has a long list of conditions that include :

1.Papilledema

2.Degenerations

3.Dystrophies

4.Trauma

5.Toxins

6.Nutritional

7.Neoplastic

8.Vascular

9.Unclassified.

retinal vein as it passes through the sub-arachnoid space round the optic nerve. The increased pressure in the sub arachnoid space changes the pressure gradient behind the lamina. There is intracellular axonal swelling which is followed by extra cellular edema.

Commonest disorders that cause papilledema in children are :

—Cysticercosis

—Leukemia

Symptoms of papilledema. Symptoms of papilledema are essentially symptoms of raised intracranial pressure. The symptoms are directly proportionate to level of intracranial pressure and its duration.

Papilledema of short duration are generally seen following head injury with extensive intracerebral bleeding, subarachnoid haemorrhage or encephalitis. Systemic symptoms of all these conditions overshadow ocular symptom.

Symptoms of papilledema can be grouped into : (1) General, (2) Ocular

General symptoms consist of headache, nausea, vomiting, neurological deficiency. Cases associated with infective process may have fever.

Headache. Headache may be acute or chronic, there is no localisation of pain. It is generally worse in the morning and worsened by coughing, sneezing and straining. Location of pain in the cranium have no localising value.

Vomiting is generally projectile, it may be inter-spaced by nausea. Neurological deficiencies are late to develop.

Ocular symptoms differ in early and late stages.

Early ocular symptoms are mostly visual.

First visual symptom is sudden loss of bilateral vision for less than a minute with recovery to original level. The blurring of vision may be just like a veil that lifts spontaneously, to total loss of light sense. The colour sense during these episodes are also diminished.

Diplopia. Diplopia may be the presenting sign, it is generally due to sixth nerve palsy. There may be skew deviation.

Late ocular symptoms are :

1.Diminished vision—Sudden diminished vision in fully developed papilledema is due to haemorrhage over the macula or infarction in the optic nerve itself.

Gradual loss of vision is due to onset of secondary optic atrophy that may culminate in loss of perception of light. There may be associated diminished colour sense.

2.Diplopia persists and may become permanent unless the cause of papilledema is relieved.

Signs of papilledema. In initial stages of papilledema, the eyes look normal. Onset of paralytic squint in a child with headache, vomiting is an ominous sign and always points towards possibility of papilledema. A sluggish pupillary reaction, afferent pupillary reaction and absent pupillary reaction are seen only when secondary optic atrophy has set in.

Ophthalmoscopic signs. Most important signs are ophthalmoscopic. Ophthalmic signs can be divided into following groups—24

1.Early papilledema

2.Established papilledema

3.Late papilledema (chronic)

4.Optic atrophy (atrophic)

Early papilledema. Diagnosis of papilledema on the basis of ophthalmoscopic findings is one of the great riddles in clinical ophthalmology. It needs to be corroborated with careful history and other investigations i.e. field changes, fluorescein angiography, X-Ray, CT, MRI etc.

1.The earliest change is blurring of disc margin that does not follow a set pattern but generally it starts at upper pole followed by lower then nasal and lastly the temporal margin.

2.Hyperemia of the disc due to capillary dilatation.

3.Filling of optic cup, swelling of the disc.

4.Swelling of the disc is most important sign. It may have to be examined by +90D to confirm.

5.Loss of spontaneous venous pulsation - It should be remembered that in 20% of persons venous pulsation is absent so its absence is not confirmatory but presence of venous pulsation excludes papilledema.

6.Blurring of peripapillary nerve layers. They look striated.

Established papilledema. Once papilledema is well established, diagnosis is not difficult.

1.The veins become dilated.

2.The disc surface is elevated over the surrounding retina which itself may be edematous. Difference of 3D between the top of the disc and retina means elevation of 1 mm. The disc may develop as much as 2 to 3 mm of elevation. The blood vessels over the disc may be obscured by edematous nerve fibres.

Exudates and haemorrhages. Initially the exudates are soft cotton wool in appearance associated with flame shaped haemorrhages. As the condition progresses changes develop on the macula in the form of hard exudates that radiate from the centre of the fovea towards the disc in the form of a macular fan.

Chronic papilledema. It takes months to develop chronic changes where the elevation is maximum almost like a small pink mushroom in which the retinal vessels disappear. By this time, the exudates and haemorrhages disappear.

Secondary optic atrophy. The edema of the disc diminishes and acquire a milky white appearance. The gliosis develops not only on the disc but also spreads on the blood vessels round the disc in the form of sheathing. The lamina remains invisible. Generally it takes 6 to 8 months to develop secondary optic atrophy.

Investigations in papilledema25, 26. Fundus fluorescein angiography is useful in differentiating pseudo elevation from true papilledema i.e. drusen, pseudoneuritis and high hypermetropia. Fluorescein angiography does not differentiate papilledema from papillitis, both show diffuse staining with profuse leaking that spreads into surrounding nerve layers.

Field changes. Fundus changes are not conclusive in papilledema. The two changes seen are :

1.Enlargement of the blind spot. This happens only when the papilledema is well established.

2.Peripheral constriction of field, this is met with in stage of secondary optic atrophy.

X-Ray skull, CT and MRI are used to pinpoint the location and size of the intracranial lesion.

Differential diagnosis of papilledema :

Papilledema should be differentiated from all other causes of disc edema i.e.

1.Papillitis

2.Pseudoneuritis

3.Drusen of optic nerve

4.Bergmeister papilla.

Unilateral Disc Swelling

It is better not to term unilateral disc swelling as papilledema. Though the basic pathology is the same i.e. venous stasis with derangement of axoplasmic flow, the lesion may extend well beyond the lamina, which never happens in papilledema.

The causes can be :

1.Ocular and

2.Orbital

Ocular causes of disc swelling are :

1.Papillitis

2.Posterior uveitis

3.Hypotony

4.Acute rise of intraocular pressure.

Orbital causes of disc edema are— Retro bulbar growths may be inflammatory like specific granuloma, orbital abscess, non specific pseudo tumour of orbit.

Treatment. Management of papilledema is essentially management of its cause. Once intraocular pressure has been reduced to normal, the papilledema starts regressing. It takes six to eight weeks for papilledema to subside. Vision may improve with regression of edema. However nerve fibre damage may have some residual effect.

Vision lost due to optic atrophy is permanent. In sudden rise of intra cranial pressure I.V. mannitol, may relieve the tension. In case of head injury, use of mannitol may be given in consultation with neurosurgeon. In chronic papilledema, the mass may be treated medically when infective. Growths both benign or malignant are removed surgically. Sometimes a shunt may be required to drain CSF in the peritoneum in the form of ventriculo peritoneal or lumbo peritoneal shunt.

Local fenestration of optic nerve sheath has not been reported to give uniform good result.

Optic Neuritis26, 27, 28

The term optic neuritis is non specific that includes all the conditions, which have loss of central vision, dyschromatopsia and central field defect, which can be acute or chronic due to involvement of optic nerve from papilla to beginning of the chiasma.

In 20% to 30% cases no cause can be found and are put in group of idiopathic optic neuritis. Other causes in children are :

1.Inflammation/infection

2.Demyelination

3.Toxic

4.Hereditary

5.Post vaccination

6.Degeneration

Direct invasion by micro-organism is rare. Most of the time, it is the inflammatory process of microbial infection that is responsible for optic neuritis, which can be26

—Ocular

—Orbital

—Brain and its coverings

—Systemic

Ocular. The optic nerve is direct extension of axonal fibres of the retina so it is very easy for infection to travel from retina to optic nerve in the form of neuro retinitis.

Other causes are choroiditis, endophthalmitis, panophthalmitis, sympathetic ophthalmia.

Orbital causes are Orbital cellulitis, thrombophlebitis, arteritis, Wegner granulomatosis, other granulomas, foreign bodies, secondary to sinus diseases.

Intracranial diseases :

Meningitis

Encephalitis Meningo encephalitis

Systemic disease :

Tuberculosis

Various types of pneumonias Poliomyelitis, influenza, mumps, measles.

Demyelination. Demyelination is a major cause of optic neuritis in adult. It is less commonly seen in younger children but children in teens may be effected by demyelination. Two common forms are Devic’s neuro myelitis optica and Schilder’s disease.

Toxic—Many drugs when given systemically can cause optic neuritis. Common drugs are—ethambutal, isoniazide, streptomycin, chloramphenicol, fluoroquinolones, metronidazole, chloroquin. The list is very long. One thing worth noting is that almost all of them are widely used for systemic diseases in children.

Hereditary. Leber’s optic neuropathy.

According to location of the lesion, optic neuritis can be : Papillitis. Inflammation of optic nerve head.

Neuroretinitis

Retrobulbar neuritis—Acute or chronic.

If the papillo macular bundles are predominantly involved. It is called axial neuritis. If the peripheral nerves are involved, it is perineuritis.

General features of optic neuritis. It is generally an acute condition mostly unilateral. Simultaneous symmetrical involvement of other side is rare. However bilateral involvement is more common in children than adults. Optic neuritis is slightly more common in girls. Incidence of optic neuritis after fifth decade is less than in second and third decade.

The main symptoms are :

I.Visual that consists of :

1.Diminished central vision

2.Dyschromatopsia

3.Defective contrast sensitivity

4.Defective stereopsis

5.Uthoff phenomenon

6.Scotoma

II. Pain in the eye

III. Neurological symptoms

Vision in optic neuritis :

1.Unilateral acute loss of vision that may deteriorate within hours to days. Vision may go down to perception of light.

2.Recovery of vision without treatment starts by second week and original vision is reached by four to five weeks.

3.Normal vision with signs of central scotoma which is relative, diminished colour and depth sense.

4.Failure to recover vision generally, is common in adults who have multiple sclerosis is not seen in children.

2.Dyschromatopsia. The coloured objects look drab and washed out. There is no real colour blindness.

3.Defective contrast. The surrounding area looks dim as if the lights in the room have been turned down.

Defective stereopsis. The patient may not be able to judge the depth well.

Bilateral optic neuritis is commonly seen in Devic’s neuromyelitis optica, Schilder’s disease, Acute disseminated encephalo myelitis, post vaccination status.

Uhthoff phenomenon. In this phenomenon vision is decreased if body temperature is raised either by exercise or taking hot food and drink, hot bath, hot weather, and anger. Even stress and anxiety can precipitate the phenomenon. Previously positive Uhthoff effect was considered to be diagnostic of multiple sclerosis. It has been pointed out that there are other conditions like Leber’s optic neuritis, toxic neuropathy, Friedreich’s ataxia where this effect can be positive.

Scotoma. Commonest field defect is central scotoma, which is more for colour than for white. Scotoma for red is most effected, other scotomas are centrocecal and paracecal, nerve bundle defect and even sectorial peripheral field loss is possible. Kind of scotoma is directly related to type of nerve fibres involved. In axial neuritis where central i.e. papillo macular fibres are involved the scotoma is central.

Pain in the eye. In case of optic neuritis patient may complain of pain with or without movement of eye. Pain on movement of eye is more common in optic neuritis and may be absent in papillitis. It is more marked if the lesion is near the apex of orbit. There are two possible explanations :

1.Due to contraction of superior or medial rectus muscles. The dural sheath that is pain sensitive gets stretched and pain is precipitated.

2.The sheath of optic nerve is stretched in swelling of the nerve and becomes painful. There may be tenderness at the insertion of superior rectus.

Pain may precede loss of vision sometimes.