Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

Sector retinitis pigmentosa

In this rare form, retinal dystrophy is localised to a sector of the retinal mid periphery. Commonest area being one of the inferior quadrants, generally involvement in both eyes is similar. The pigmentation and attenuation of vessels are same as in typical retinitis pigmentosa. The area of dystrophy being localised, there is no night blindness, field defect corresponds to the area of retina involved. Dark adaptation may be abnormal. ERG is also subnormal. The patient has good central vision. The two common causes of localised pigmentation should be kept in mind before diagnosis of sector retinitis pigmentosa. They are trauma and localised retinal inflammation. The condition does not require any treatment.

Central retinitis pigmentosa (Inverse retinitis pigmentosa)

In these cases pigmentary changes similar to retinitis pigmentosa occur round the macula. Due to central involvement, these cases are misdiagnosed as cone or choroidal dystrophy. As the central retina is involved, diminished central vision, reduction of vision in bright light, defective colour vision and positive central scotomas are common. On rare occasion the retinal vessels get attenuated and pigmentation spread to the periphery over years. ERG is always subnormal. In adults it should be differentiated from chloroquine maculopathy and other dystrophies of macula. There is no specific treatment. The children may require rehabilitation.

Retinitis pigmentosa sine pigmento

The patient present with diminished night vision without pigmentation. On examination they have attenuated blood vessels and waxy pale disc. It may develop pigmentation years after onset of night blindness. The ERG is not recordable. Family members may suffer from typical retinitis pigmentosa.

Unilateral retinitis pigmentosa

Like sector retinitis pigmentosa, there is doubt if unilateral retinitis pigmentosa can exist without involvement of the other eye. The cases that have been reported as unilateral retinitis pigmentosa had abnormal ERG and EOG in the eye with pigmentation. However possibility of trauma, inflammation and vascular anomaly should be excluded. It is possible that the other eye may develop pigmentation later.57

Retinitis punctata albescens

This is a condition of diminished vision, has multiple white dots, scattered all over the retina instead of black pigments of typical retinitis pigmentosa. The vessels are thin and the field is constricted like in retinitis pigmentosa. The condition must be differentiated from other causes of white spots on the retina i.e. retinal drusen and asteroid hyalitis.

Retinitis pigmentosa associated with systemic disorders

The list of systemic disorders that have signs of retinitis pigmentosa are either hereditary or have disturbances of metabolism, is long. They can be divided into:

1.That have predominant skeletal involvement—Laurence-Moon-Biedel-Bardet syndrome, Marfan’s syndrome.

5.Mucopolysaccharidosis

6.Lipidosis

7.Spino ponto cerebellar degeneration

8.Miscellaneous—Progressive external ophthalmoplegia, myotonic dystrophy.

Laurence-Moon-Bardet-Biedle syndrome

Obesity in a child is most striking feature, which is present in 90% of cases. On close look, the child may have polydactyly and syndactyly which is obvious at birth and hypogenitalism. These children have low IQ and overall mental retardation. Commonest symptom is night blindness that starts by ten years of age. Soon to this is added diminished central vision due to involvement of macula. Some children may have nystagmus. The fundus picture is similar to retinitis pigmentosa i.e. bone spicule pigments on the periphery, thinning of retinal vessels and waxy pale disc. The field changes, ERG and EOG changes are similar to typical retinitis pigmentosa. Some children may show albipuntate changes. Other systemic disorders include - brachycephaly, short stature that makes these children look more obese, renal disorder, deafness, congenital heart disease. The disease is an autosomal recessive disorder.

All children with polydactyly or syndactyly should be observed for unusual weight gain and screened for pigmentation changes in the retina. There is no specific treatment.

Rafsum’s syndrome

This is an autosomal recessive disorder. The syndrome consists of peripheral neuropathy, ataxia, night blindness, and atypical pigmentary dystrophy with constricted retinal vessels, poor dark adaptation and sub normal ERG. The pigments are in clumps and look more or less like pepper and salt appearance rather than typical bone spicule. The condition is a disorder of metabolism of fatty acid. Both serum and urine contain phytanic acid. It is claimed that dietary restriction of fatty acid can improve the condition. Other systemic involvement’s are - Progressive deafness, reduced corneal sensation, loss of hair, icthyosis. There may be conduction defect in the heart that may prove to be cause of sudden death.

Usher’s syndrome

Usher’s syndrome is a major cause of genetic hearing defect. It includes neuro sensory deafness, vestibular disturbance and night blindness. Association of neuro sensory defect along with degeneration of pigment may be traced to similarity in development of retinal pigment and the epithelium of organ of Corti. It is an autosomal recessive disorder.

Night blindness may start between ten to twenty years of age and progress relentlessly. Associated macular lesion is cause of diminished distant vision. Peripheral field is constricted, there is sub normal ERG, EOG and dark adaptation.

Cokayne’s syndrome

This is autosomal recessive disorder that has diminished night vision, retinitis pigmentosa, infantile deafness, pre mature old age, dwarfness and mental retardation.

Bassen-Kornzweig syndrome (abetalipo proteinemia)

It is an autosomal recessive disease seen mostly amongst Jew’s. The condition is detected in first decade with diminished night vision with pigmentary changes in the retina. RBC’s show acanthocytosis. These children generally suffer from malabsorption syndrome. Serum cholesterol and serum beta lipo proteins are less than normal. There may be spinocerebellar ataxia, which progresses slowly and is stabilised in adults. Oral administration of large doses of vitamin E and A are said to be helpful.

Causes of retinal pigmentation without dystrophy are:

1.Salt pepper fundus due to congenital rubella, syphilis, influenza, cystinosis, rubeola.

2.Drug induced pigmentation—Phenothiazine, chloroquine (macular pigmentation), indomethacin, quinine.

3.Trauma—Small laser burns, cryo spots

4.Congenital melanosis (in clumps)

Diagnostic procedure for retinal dystrophy

1. History—History gives important clue in diagnosis of retinitis pigmentosa.

(a) Night blindness. If a child under ten years of age presents with night blindness first is to find out if it is due to vitamin A deficiency or retinal dystrophy.

A child with vitamin A deficiency and night blindness invariably has other signs of protein caloric malnutrition, xerosis or even keratomalacia. Such night blindness improves within 24 hours to 72 hours following administration of water soluble injection of vitamin A or within a week following oral administration of vitamin A concentration 200,000 IU on two consecutive days. An adult with night blindness does not improve with vitamin A administration.

(b) Positive family history

(i) Night blindness.

(ii) Proved retinitis pigmentosa among siblings, parents and other blood relatives. (iii) Consanguinity among parents, grand parents.

(c) Evidence of other neuro sensory disorders like deafness, ataxia, mental retardation.

2. Field changes

(i) Ninety percent of cases with retinitis pigmentosa have ring scotoma, by the time they report with night blindness which is not cured by therapeutic dose of vitamin A.

(ii) The field changes usually start as isolated scotoma concentric with equator in the inferior temporal area. This gradually enlarges on either end to become a ring scotoma. Once the ring has been formed, the scotoma expand both anteriorly and backwards leaving only an island of vision.

3.Dark adaptation. This is a sensitive test second only to ERG to show abnormality even before the fundus findings appear. It shows elevation of rod threshold. The cone threshold may also be raised.

4.Electro retinogram. ERG is almost always sub normal even before the fundus changes develop. Scotopic ERG is more markedly involved than photopic ERG.

ERG of the family members may show abnormality without night blindness. Hence this is used to screen members of the family for retinitis pigmentosa.

5.Colour vision defect is more marked in cone dystrophy.

6.Fluorescein angiography. This is not a specific test. It shows thinning of retinal vessels, diffuse hyper fluorescence due to hypertrophy of pigment epithelium.

Cone and cone-rod dystrophies

These disorders are as common as rod dystrophies but do not have prominent symptoms like night blindness. They are associated with diminished central vision. The subtle cases may be missed or misdiagnosed as amblyopia.

The symptoms consist of diminished central vision, poor vision in bright light, photophobia, defective colour vision and nystagmus.

The cases are generally sporadic but autosomal dominant and autosomal recessive inheritance is also possible.

The conditions are broadly divided into two groups:

1.A rarer form of progressive cone dystrophy which again on the basis of fluorescein pattern have been divided into type I and type II.

2.Commoner form of stationary cone dystrophy.

Progressive cone dystrophy

The condition is bilateral, first detected in first decade as acquired diminished distant vision, photophobia and nystagmus. On examination the children have severe colour vision defect which may end in achromatopsia in later stages of life.

The macula has a bull’s eye appearance, which consists of clear central area surrounded by zone of pigmentary changes, which is best seen by fluorescein angiography that have multiple window defects without staining.

To begin with, the optic nerve may show temporal pallor which may become pale later. Thinning of retinal vessels also is a late feature.

Visual field shows central scotoma.

ERG—Photopic ERG is abnormal with small b wave. Scotopic ERG is normal, EOG is generally normal.

Stationary cone dystrophy

The condition is congenital and non progressive autosomal recessive.

The symptoms are similar to progressive cone dystrophy, as far as diminished central vision, abnormal colour vision, nystagmus, photophobia, diminished vision in bright light are concerned. Only difference is that the condition is stationary in nature. The condition is more frequent than progressive form. The colour defect is rodmonochromatism.

On examination, the retina may look normal with loss of foveal reflex and pigmentary change in the macula.

Fluorescein angiogram is normal so is EOG.

The dark adaptation and ERG are sub normal. The dark adaptation shows normal rod adaptation and abnormal cone adaptation. In ERG the photopic response is poor.

Congenital achromatopsia

This is an autosomal recessive disorder of macula without many visible clues. The condition is congenital in nature. It can be rod monochromatopsia (typical) or cone monochromatopia (atypical). The latter is rarer than the former. To these children all colours are but shades of grey.

The rod monochromat has diminished central vision, photophobia and nystagmus.

Congenital night blindness (stationary)

There is early onset of night blindness, associated diminished distant vision. Moderate to high myopia is common. Colour vision is not affected, photopic field is normal. The ERG is sub normal, which is not influenced by mode of inheritance. There are three modes of inheritance i.e. autosomal recessive, autosomal dominant and x linked. The x linked have poorest distant vision. The fundus does not show any change except usual myopic change. The ERG shows normal scotopic ‘a’ wave and minimal response in scotopic ‘b’ wave.

Ganglion cell dystrophy of retina Cherry red spot

Red spot (Cherry red) in the macula is a non specific finding in many retinal conditions mostly due to disturbance of metabolism of specific enzymes. These are generally bilateral, hereditary disorders that have deposition of glycosides of various tissues of the body like central nervous system, besides eye. The fovea is mainly involved. Other non biochemical causes can also cause cherry red spot of macula.

Common causes of cherry red spot of macula can be brought about by:

1.Biochemical causes (glycolipids and phospholipid)

2.Macular hole —Traumatic

—Non traumatic

3.Macular cyst

4.Central retinal artery obstruction

5.Comotio retinae.

Cherry red spot is a contrast phenomenon where normal macular vasculature stands out prominently among pale retina. The pallor of the retina is due to deposit of various chemicals in the ganglion cells leading to cell death.

Cherry red spot maculopathy Common causes are:

•Tay-Sach’s disease (Infantile, amaurotic, familial idiocy) Batten-Mayou disease

•Niemann-Pick disease

•Sandhoff disease

•Generalised gangliosidosis

•Sialidosis

•Metachromatic leuco dystrophy

Most of the above conditions are hereditary, may have family history. Some of them are seen in specific races (Tay-Sach’s), starts early in life, have various degrees of visual loss, have multiple systemic involvement.

The other type of involvement of macula leads to pigmentation of macula and flecks on retina. They are called—flecked retina syndromes. These disorders are dystrophies of retinal pigment epithelium.

The two main causes of flecked retina syndrome are fundus flavimaculatous and Stargardt’s disease. There is some difference of opinion regarding nomenclature of these conditions. Some consider that Stargardt’s disease is late manifestation of fundus flavimaculatous because they have similar symptoms, both have same hereditary and age of onset is similar.

The main point of differentiation is presence of macular atrophy, which is present in Stargardt’s disease and absent in fundus flavimaculatous.

Fundus flavimaculatous

This is an autosomal recessive disorder, is bilaterally symmetrical. The flecks, which are accumulation of acid mucopolysaccharides and lipofucin in the retinal pigment epithelium, develop in the posterior pole. The flecks are small and discrete yellowish white spots with irregular margins. The lesions may be of various shapes i.e. fish like, semi circular or circular. The flecks are known to disappear or absorb leaving areas of atrophy of retinal pigment epithelium. New flecks may appear later so long the flacks are away from the macula, the patient is asymptomatic, the flecks appear on the macula the vision falls and continue to fall gradually, never reaching a level of legal blindness. Involvement of macula may cause poor colour sense. Dark adaptation, ERG and EOG are normal. Fluorescein angiography shows hypo fluorescence in early stage and hyper fluorescence in later stage. The lesions have blurred margin without leak.

Stargardt’s disease58

As mentioned early some authors consider Stargardt’s disease as a late presentation of fundus flavimaculatous. The characteristics of Stargardt’s diseases are progressive, bilateral, symmetric loss of vision in young patients who had subnormal central vision due to atrophy of macula. It is autosomal recessive disorder. It is more common inconsanguinity. The patient has poor vision in bright light, which he may express as glare or photophobia. Part of the diminished vision is explained on the basis of myopia, which is common error of refraction. In early stages the child is brought with loss of one or two lines on Snellen’s chart that gradually progresses to 1/60 or less. The children with Stargardt’s disease have red green colour defect that may terminate into achromatopsia.

Diagnosis is on the basis of fundus findings and fluorescein angiography.

Fundus—In initial stages the fundus may look normal with moderate uncorrectable diminished distant vision that may be confused with amblyopia or functional. The first visible sign is loss of foveal reflex. This is followed by bull’s eye appearance that has normal retina surrounded by area of de-pigmentation. By this time some flecks may develop in the macula giving a name of varnished macula. This is followed by onset of atrophic changes in macula and the macula has a brownish appearance called beaten bronze appearance. The choroidal vessels may become visible through the atrophic macula. Small flecks may appear round and into the macula. Optic nerve may show temporal pallor.

Fluorescein angiography

Changes in angiography may be visible before the ophthalmoscopic changes occur. The typical picture in normal retina with zone of hyper fluorescence all round without leak.

Dark adaptation and ERG are normal but EOG findings are abnormal. The central field may show relative scotoma. The condition should be differentiated from dominant progressive foveal dystrophy.

There is no specific treatment.

Differential diagnosis of flecked macula consist of—

Progressive and stationary albipunctate retinal degeneration and Uyemura’s disease all have diminished night vision, abnormal ERG, EOG and dark adaptation as all of them are rod dystrophies with flecks on the retina.

Vitelli form macular dystrophy

This is autosomal disease, starts between four to ten years of age, may be bilateral but not always simultaneous or symmetric. Mode of presentation is variable. The child may be asymptomatic yet can have a full blown disease. The diagnosis is straight forward, on ophthalmoscopy typical egg yolk appearance of the macula is seen from which it gets its name of vitelli form dystrophy. This is also known asBest’s disease. The carriers can be asymptomatic with normal macula but abnormal EOG. Association of hypermetropia, esotropia and amblyopia is common.

Symptoms depend upon the stage of the disease. The disease has been divided into pre vitelli form and vitelli form stages, the latter is again divided in to stage of pseudo hypopyon, rupture of cyst and complication of rupture.

The pre vitelli form stage is asymptomatic, even fundus changes are absent but EOG done at this stage is abnormal. Suspicion of the disease arises when one eye is already in vitelli form stage.

The vitelli form stage consists of diminished central vision. On fundus examination an ill defined yellow spot develops generally over the fovea but may be eccentric. The spot is in the retinal pigment epithelium most probably due to accumulation of lipofuscin forming an orange cyst similar to sunny side up egg yolk that may be 1/3 or half of the optic nerve head. Retinal vessels travel over the cyst.

Stage of pseudo hypopyon

There is no accumulation of pus. The name is acquired due to settling of the lipofucin at the bottom of the cyst, upper part of the lesion may be absorbed. The pseudo hypopyon blocks the

fluorescein, the upper part shows hyper fluorescence due to atrophy of the retinal pigment epithelium. It takes about ten to twenty years for this stage to develop, vision is minimally reduced, EOG is abnormal.

Stage of rupture of the yolk

The cyst changes from sunny side up to appearance of scrambled egg with diminished vision.

Stage of complication

The complication consist of formation of choroidal neovascularisation, with sudden and profound fall of central vision, there may be vitreous haemorrhage. There may be glial proliferation and formation of a hypertrophic scar. The macula may develop an atrophic patch through which the underlying vasculature may show as pink glow surrounded by white glial tissue.

Dominant drusen of the retina

This condition should not be confused with more frequent condition i.e. drusen of optic nerve. They are of different etiology, clinical presentation and pathogenesis.

In drusen of retina there is deposition of yellowish white material in the posterior pole in retinal pigment epithelium and Bruch’s membrane in the macula or round it. There are two types of retinal drusens -

1.The primary (familial)

2.The secondary - Secondary to local ocular disease like benign choroidal nevus or systemic conditions.

The primary familial drusen is inherited as autosomal dominant disorder. It is a bilateral condition, which becomes evident in second decade of life as yellowish white circular raised area, which may be discrete or may confluent to form large plaque that may get calcified in fifth decade. In early stages the deposits may be confused with other white dots on the retina i.e. hard exudates, fundus albipunctatus, and asteroid hyalopathy. Lesion on the nasal side of the disc is more common in familial type.

The drusens in pediatric age group are symptomless and are discovered on routine fundus examination, do not require any treatment. Persons with macular drusen are predisposed towards age related macular degeneration, a major cause of blindness in aged.

Peripheral retinal degenerations59

There are many retinal degeneration on the periphery of the retina. Most of them develop after third decade. Some of them predispose rhegmatogenous retinal degeneration, others are diagnosed on routine examination and are asymptomatic. The degenerations are bilateral and may be symmetric.

Common peripheral retinal degeneration are:

1.Lattice degeneration

2.Snail track degeneration

3.Cystoid degeneration

4.White with pressure

5.White without pressure

6.Peripheral chorio retinal degeneration (paving stone or cobble stone degeneration)

7.Chorio retinal atrophy

8.Retinoschisis

All the above conditions are not seen in children though many of them start in childhood. Only peripheral retinal degeneration is seen in childhood is lattice degeneration.

Lattice degeneration of the retina

Lattice degeneration is the commonest form of peripheral retinal degeneration about eight percent of eyes have asymptomatic lattice degeneration which are discovered on routine examination of the retinal periphery by indirect ophthalmoscope. Commonest site for such patches is lower temporal quadrant near the ora. They are more common in moderately myopic eyes. It is common in Marfan’s syndrome as well as Ehlers Danlos syndrome and Wagner’s disease. In about 30% of cases of rhegmatogenous retinal detachment, lattice degeneration may be the predisposing cause. The degeneration starts in about ten years of age as scattered small patches on the periphery. The condition is well established in second decade. There may be family history of retinal detachment. It is equally seen among boys and girls.

Fundus picture

The lesion may be single or multiple, they are generally parallel with the equator but can be radial, parallel to peripheral blood vessels as in Stickler’s syndrome. There may be more than one row of patches of lattice degeneration in the same quadrant. The degeneration derives its name from white lace like pattern caused due to sclerosed vessel in the patch. The area of degeneration is generally a spindle shape patch. The lattice may be associated with snowflakes, white with pressure and hyperplasia of retinal pigment epithelium.

Symptom

The condition may go without symptoms but may be associated with flashes of light and floaters, which should be taken seriously and eye examined with indirect ophthalmoscope.

Retinal holes are common in lattice degeneration, they develop in the substance of the lattice. All holes are not symptomatic, occasionally they are responsible for retinal detachment which is heralded by development of retinal tear. The tear generally develops outside the island of lattice on the posterior border. They are more common in moderate myopes and eyes with acute posterior vitreous detachment. Occasionally latticed part may be seen on the flap of retinal tear.

Snail track degeneration

There is doubt if this condition is a separate entity or precursor of lattice degeneration or its variation because their position and distribution on the retinal periphery is the same, both are associated with snow flecks. Complications of snail track degeneration are same as lattice degeneration.

Retinoschisis

In retinoschisis, the sensory retina is splits into two layers, in contrast to retinal detachment where the retina separates between the pigment epithelium and sensory retina. In retinoschisis the split occurs between the nuclei of visual cells and bipolar cells.

The condition can be divided into juvenile (idiopathic) and senile retinoschisis. (See page 403.)

Congenital retinoschisis

Congenital retinoschisis is present at birth but not diagnosed unless looked specifically in a neonate, born to parents, either of whom is known to suffer from congenital retinochisis. Inheritance is varied. Commonest inheritance is x linked receive. Generally the condition is diagnosed when the child reaches school age and is more often diagnosed as shallow retinal detachment rather than retino schisis. This is true with other types of retinoschisis as well.

Juvenile retinoschisis

This is a bilateral, symmetrical condition, the hereditary is same as congenital retino schisis. Some authors feel that juvenile retinoschisis is nothing but late feature of congenital retinoschisis.

The lesion starts in the lower temporal quadrant in a hypermetropic eye. The separated inner table balloons inwards, the ballooned layer is almost transparent, with blood vessels. The two separate layers are best seen by +90 D or gonio lens. It may have round holes in it, some times there may be hole in the inner table also. The balloon extends up to ora anteriorly and may involve the macula behind.

Management

The congenital retinoschisis is generally non progressive, may have fair vision without any surgical intervention. However if the condition progresses to involve the macula or rhegmatogenous retinal detachment develops, then the lesion must be treated by laser photocoagulation and scleral buckling.

Retinal detachment60

The term retinal detachment is a misnomer as a clinical diagnosis because whole of the retina is not detached but there is inter retinal separation of the layers and it is better to call it retinal separation. However it is difficult to replace old terminology by new, hence, the term retinal detachment has stayed in clinical practice.

The retina develops from the two layers of the optic cup. The outer layer contributes to form the pigment epithelium. The rest of the nine layers i.e. the sensory retina develop form the inner layer of the optic cup. In early stages of embryogenesis, the gap between the two is visible, the gap gradually diminishes and ultimately disappears leaving a potential space which is liable to be opened up through out the life if something could get in to it.

What keeps the two layers in contact with each other is not well understood. The two theories that are generally put forward are60:

1.The microvilli of retinal pigment epithelium inter digitate with the outer end of the photo receptors, creating a bond between the two layers.