Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

demonstrated by fluorescein angiography. The causes of retinal aneurysm in children are Coat’s disease and early onset peri phlebitis.

Anastomosis of retinal vessels

The retinal arteries are end arteries, they do not anastomose normally except as congenital anomaly between central retinal artery and cilio retinal artery. There may be anastomosis between veins as in angiomatosis. There may be anastomosis between the retinal circulation and choroidal circulation in toxoplasmic chorio retinitis.48

Inflammation of retina

Inflammation localised to retina is less common than retino choroiditis and neuro retinitis. Associated vasculitis is common. Retinitis can be localised or diffuse. It may involve sensory retina or retinal pigment epithelium separately or in combination.

Retinitis has been divided into two basic types:

1.Primary, where retina and retinal vessels are involved as primary site.

2.Secondary, when inflammation spreads from choroid mostly and optic nerve less frequently.

It can be non specific or specific like viral, bacterial, fungal or parasitic when associated with systemic diseases it can be bilateral, otherwise in case of unilateral retinitis, the other eye may get involved later. Retinitis in children is mostly endogenous. It can be purulent, exudative or granulomatous. Purulent retinitis can be acute or sub acute. Acute purulent retinitis is mostly due to lodging of pus producing bacteria or fungus in septicimic child. Generally the bacteria reaches the retinal vasculature from distant organ and cause purulent retinitis which may pass into endophthalmitis or even panophthalmitis within days or weeks. The condition starts in an acutely ill, malnourished child, as sudden gross loss of vision without pain or congestion. On examination the retina is oedematous with dilated veins. There may be superficial exudate and haemorrhages. If the disease process progresses, it becomes painful and congested, with still further loss of vision going into endophthalmitis and loss of eye. The condition is generally unilateral but may be bilateral. Management is early recognisation of ocular problem and treatment of systemic septicimia.

Sub acute infective retinitis (Retinitis of Roth)

This is milder form of embolic retinitis where an embolus from heart may get lodge in the capillaries of the retina in the posterior pole. Commonest condition leading to sub acute retinitis is sub acute bacterial endocarditis. The lesion may be single or multiple. There may be recurrence of the episode. There is generally very low grade of retinal reaction. The typical lesion is a large superficial haemorrhage with white centre. A lesion near the macula draws attention early. Most of the time the systemic condition overshadows the ocular pathology. Treatment is directed to the systemic condition. Other causes of Roth’s spot should be excluded.

Specific retinitis of clinical importance in children are:

1.Viral

2.Bacterial —Non granulomatous

—Granulomatous

3. Parasitic

Viral retinitis in children

Many of the viruses with systemic involvement may cause primary retinitis. Viral infection of choroid is invariably associated both DNA group of viruses i.e. herpes viruses which produce chorio retinitis. RNA viruses i.e. rubella, rubeola (measles) cause retinitis. Healthy adults rarely develop viral retinitis. It is common in neonates as part of intra uterine infection, the two examples are rubella and cytomegalo viruses. The viruses are inter cellular, obligatory parasites that cause necrosis and death of the cell leading to permanent damage to the retina. Vasculitis is common in retinitis, the inflammatory response to virus is immune mediated. Retinal hypoxia is frequent. It is due to occlusion of retinal vessels. The patches of the retinitis may be localised or scattered. The after effect may be simple pigmentary disturbance without visual loss to devastating visual loss due to exudates, haemorrhages, gliosis, retinal detachment, secondary glaucoma and cataract. Optic neuritis is more common in lesions of the posterior pole. It is difficult to diagnose the exact virus responsible for retinitis by ophthalmoscopy because most of them have similar features of retinal edema, superficial exudates and haemorrhages, cells in the vitreous. Specific diagnosis is possible only with positive viral culture and serology.49,50

Common viruses that cause retinitis in children are:

Rubella, herpes simplex, herpers zoster, cytomegalo virus, Epstein-Barr virus.

Rubella retinitis is a congenital bilateral retinitis, also known as embryonic pigmentary retinopathy as the predominant feature is pigmentary disturbance of retina without vascular changes or night blindness. The condition is seen in 50% of children born of mothers who have contracted rubella in first trimester of pregnancy. In absence of more serious ocular involvement like rubella cataract and rubella glaucoma, the condition may go unnoticed unless looked for specifically. The condition does not involve macula, hence there is no diminished vision. However as a late complication there may be sub retinal neovascularisation. As there is loss of pigment from the RPE, fluorescein angiography shows area of hyper fluorescence. There is no treatment for rubella retinitis. The best management is prevention of rubella in mother that is achieved by immunising every girl child by rubella vaccine in childhood. Equally important is to differentiate the fundus picture from other embryonic retinopathies like congenital syphilis, varicella, influenza and radiation to the mother in first trimester by doing torch test and other serological tests for rubella. Commonest retinal dystrophy that presents with pigmentary changes is retinitis pigmentosa and its allied conditions. Retinitis pigmentosa is always associated with night blindness, have attenuated blood vessel and coarse spider like pigments, mostly in mid periphery. The pigments in rubella retinopathy have salt and pepper mottling.

Rubeola retinitis (Measles retinitis)

Involvement of retina is rarer than involvement of cornea and conjunctiva. Retina is involved when the child is serious enough to develop subacute sclerosing panencephalitis which itself is a devastating neurological disease. The ocular involvement consist of bilateral necrotising retinitis involving macula. There may be evidence of optic neuritis with superficial haemorrhages and exudates which is healed by formation of chorio retinal scar.

There is no separate treatment for ocular manifestation. The child should be under treatment of pediatrician. The best management consist of immunisation of children routinely by measles vaccine.

Herpes simplex retinitis

It is seen in neonates who suffer from systemic herpes simplex infection that may include herpes simplex encephalitis. It may develop in children who are on systemic immuno suppressive drugs. Fundus picture consists of superficial exudates, haemorrhages, sheathing of vessels with vitritis. Rarely there may be exudative retinal detachment.

Management consists of treatment of systemic herpes simplex.

Herpes zoster retinitis

As a general rule, herpes zoster infection is rarer in children as compared to adults. Retinitis is still infrequent. It mostly involves posterior pole. It develops after cutaneous lesions have subsided. The intra ocular lesions are immune mediated. There is localised necrosis of retina, vasculitis is common.

Treatment consists of systemic antiviral drugs along with judicious use of steroids.

Cytomegalo virus retinitis (C.M.V.)

Incidence of cytomegalo virus has shown a sharp upward swing in past one decade due to increased awareness among the ophthalmologists and increase in number of susceptible persons. There are two modes of contracting the disease; the first is transplacental spread from the mother and second is seen in immunocompromised children. More than 80% of general population show antibodies to the virus without manifest signs or symptoms. The incidence of retinal infection rises with fall in immuno compatibility in children by way of spread of HIV from mother to the foetus. Use of infected needles, transfer of infected body fluid, repeated blood transfusion by unsafe blood transfusion, prolonged chemotherapy for malignancy and immuno suppressive drugs for organ transplant increase the risk.

Congenital cytomegalo virus retinitis presents as localised necrotising retino choroiditis any where on the retina, common site being macula and retinal periphery that may lead to optic atrophy. On some occasion there may be pan retinal involvement with acute necrosis. Differential diagnosis consists of toxoplasmosis, and nematode infection.

The acquired disease is common among children with AIDS, The virus is a member of herpes virus family. It reaches the retina by hematogenous spread. Onset on CMV is CD4 plus cell dependent. It never occurs in AIDS patient who have CD4+ count more than 50/mm3. It begins as unilateral disease to become bilateral soon. The condition is uniformly vision threatening when not treated. Retinitis does not require separate treatment, usual treatment by specific triple anti viral drugs for AIDs.

Bacterial retinitis

Bacterial retinitis could be acute non granulomatous due to spread of pyogenic organism from systemic focus of infection or may be exogenous due to penetrating injury, most of the time leading to endophthalmitis.

Incidence of granulomatous retinitis has been reduced in recent years due to effective chemotherapy of tuberculosis, syphilis, which used to be two main causes.

Acquired syphilitic retinitis rarely occurs in children. More common is congenital syphilitic retinitis in children that causes embryonic pigmentary retinopathy with typical pepper salt appearance without night blindness.

Treatment consists of treatment of systemic syphilis. Tuberculosis produces tubercular chorio retinitis.

More common granulomatous retinitis are due to toxoplasmosis and toxocara infesta-

tion.

Toxoplasmal retinitis

Toxoplasmosis retinitis is perhaps the most common causes of retino choroiditis involving macula in children. There are two modes to acquire toxoplasmosis. The commonest is transplacental transfer of the parasite from the infected mother to the foetus. The second less common is acquired-form seen in adults.

In between the two is a condition where old lesions are reactivated and present as active lesion little away from the original macular lesion, and called satellite lesion.

Systemic acquired involvement is mild, which may be passed off as usual cold unless the patient is pregnant or immuno-suppressed. In an infected pregnant woman there are 40% chances that the foetus will be involved and the child will have multi systemic involvement. The foetus is only at risk if the mother is infected during pregnancy. Subsequent pregnancies are safe from toxoplasmosis.

The three clinical features of congenital toxoplasmosis are chorio retinitis, convulsion and intracranial calcification. 80% of infants with congenital toxoplasmosis will have retinal involvement.

The parasite has predilection for the nerve fibre layers of the retina. It is bilateral in 8085% of cases. Commonest site in retina to be involved is macula, which is generally missed unless looked for or the child has other systemic signs of toxoplasmosis like convulsion, hepatespleenomegaly. All children with convulsion and hepatospleenomegaly should have their fundus examined for evidence of toxoplasmal chorio retinitis.

The condition is generally diagnosed late when the child presents with esotropia. By that time the lesion is a healed scar, that may be many times larger than optic disc, with chorio retinal scar on the periphery and white centre.

The condition should be differentiated from congenital coloboma of the macula. At this stage there is no effective treatment available. However the child should be under regular observation for years, as there is a possibility of reactivation of the lesion.

The reactivated lesions may be single or multiple, always behind the equator. It is associated with anterior chamber reaction, vitreous precipitates, vitreous detachment and papillitis.

Diagnosis

There are many tests available to diagnose toxoplasmosis, common among them are serological tests to detect anti toxoplasmo anti bodies, Hemagglutination test, indirect fluorescent anti body test, ELISA test. Titers of these tests are lower in ocular lesions. Any positive titer is significant with characteristic fundus picture. x-ray skull is associated with intra cranial calcification.

Differential diagnosis

Differential diagnosis of congenital toxoplasmosis in congenital coloboma of macula. Commonest presentation of acquired toxoplasmosis of retina is a localised necrotising retinitis. All the

infective conditions that produce similar picture form a long list. Possible causes are— Tuberculosis, syphilis, cytomegalo virus retinitis, herpes simplex retinitis, acute retinal necrosis, candida retinitis. The above conditions may be superimposed on toxoplasma infection, hence mere presence positive serological results for toxoplasma does not rule out these.

Management

There is no prophylaxis against toxoplasmosis. Treatment consists of:

1.Systemic anti toxoplasma chemotherapy

2.Local treatment of anterior segment involvement

3.Management of squint, amblyopia.

Chemotherapy is indicated in vision threatening retino choroiditis involving the macula, papillo macular fibre lesions near the disc or severe vitritis.

The basic pathology of toxoplasmosis retinitis is active multiplication of organism accompanied by inflammatory reaction and scar formation. The aim of the treatment is to minimise multiplication and destroying the already present organism by chemotherapy along with reduction in inflammation by anti-inflammatory drugs. Chief out of them being systemic steroids.

Common drugs used are (They should be given in consultation with pediatrician)

1.Sulphonamide

(a) Sulphadiazine alone (b) Triple sulpha.

2.Pyrimethamine. Adult dose is loading dose of 75 mg-150 mg followed by 25-50 mg daily for four weeks. The drug is folic acid antagonist so it should be seen that the child is not prescribed folic acid during this treatment. Folinic acid in a dose of 5 mg. three times is said to protect bone marrow.

3.Clindamycin is given four times a day for three weeks. Clindamycin is known to produce pseudo membranous colitis.

4.Other newer drugs available are— Atovaquone, roxithromycin and azithromycin. Systmic steroid should be used under cover of chemotherapy with usual precaution.

Retinal toxocariasis51,52

Ocular toxocariasis is a world wide problem. It is seen more commonly in developing countries and in children who come constantly in contact with puppies that are infected by toxocara canis. Children are infected by swallowing eggs of the parasite that are found in the soil, contaminated by faeces of infected puppies. The eggs are converted as larva in the stomach and intestine of the child and penetrate the wall of the bowel and reach systemic circulation that takes them to distant organs including retina. One of the peculiarities of the parasite is that it is never converted in to adult worm is humans hence the stool of the child never shows evidence of worm infestation. It can infect the eye without systemic involvement. In fact concurrent ocular and systemic infection is rare.

There are three modes of presentation of intra-ocular toxocariasis:

1.Sub macular granuloma that later involves whole of the macula

2.Peripheral granuloma that may present as parsplanitis

3.Larval endophthalmitis.

The macular granuloma is limited to posterior pole hence there is no anterior segment reaction or redness but vision is poor. Solitary localised macular lesions may go unnoticed as they are generally unilateral or may present with squint, otherwise they are discovered on routine vision check up. There is generally pre retinal gliosis that may cause grey reflex on retinoscopy.

The peripheral retinal granuloma is also solitary and unilateral with minimal anterior chamber reaction similar to parsplanitis. The lesion is oval nodule with pre retinal gliosis and formation of vitreous bands that may extend back into to macula or even disc causing traction retinal detachment.

Larval endophthalmitis is the most extensive form of the infection of chronic nature and is a cause of white reflex in pupillary area. It may terminate in complicated cataract, glaucoma and blindness. Differential diagnosis consists of retinoblastoma, persistent primary hyperplastic vitreous, Coats disease, endo-genous bacterial endophthalmitis, toxoplasmosis, retinopathy of prematurity, congenital and traumatic cataract, familial exudative vitreo retinopathy.

The diagnosis is by exclusion. There is no specific test for toxocariasis. ELISA is most sensitive test but also gives false positive result in about 10 percent of cases.

Management consists of prevention, as far as possible, deworming of household puppies is best available method. Ant helminthics given to the child have not proved to be effective.

Retinal vasculitis

Retinal vasculitis is rare in children. Idiopathic periphlebitis (Eales disease), which is commonest form of periphlebitis in adults between 20 to 40 years of age is not seen in children, however there may be secondary vasculitis in older children due to parsplanitis, tuberculosis, cytomegalo virus. They may present as Eales disease. The peripheral retina is involved more than posterior pole. The peripheral lesion may go unnoticed unless they present with diminished vision. Retinal changes include peripheral vasculitis, sheathing, neovascularisation, superficial and subhyaloid haemorrhage, retinal band, traction detachment, non perfusion of vessels.

Treatment consists of:

1.Treatment of the primary cause

2.Management of neovascularisation and non-perfusion by laser photo coagulation.

3.Management of non absorbing hemorrhage by vitrectomy with endo laser photo coagulation.

4.Management of retinal detachment.

Vascular retinopathies in children

Vascular retinopathies especially diabetic retinopathy are common cause of blindness in adults, fortunately they are very rare in children.

Common vascular retinopathies in adults are:

1.Diabetic retinopathy

2.Hypertensive retinopathy

3.Renal retinopathy

4.Toximia of pregnancy

5.Sickle cell retinopathy

6.Atreosclerotic retinopathy.

Proliferative diabetic retinopathy may be seen in older children with type I diabetes53 Similarly hypertensive retinopathy can be seen in secondary hypertension due to any cause as Schie’s grade IV classification. Chronic glomerulo nephritis may present as renal retinopathy comprising of sclerotic changes in arteries, retinal edema, superficial haemorrhages, occasional deep haemorrhages, soft exudates, may have macular fan and blurring of disc margin.

Retinal dystrophies and degenerations

Although both the terms dystrophies and degeneration are used as interchangeable terms for same group of disease, they are not synonymous.

Dystrophies are abiotrophic disorder, which means that they are genetically determined disorders, which are not evident at birth, manifest late in life. There is premature degradation of highly differentiated cells in specialised tissue like brain, and retina. The cause of dystraphy is supposed to be a programmed death called apoptosis. The dystrophies are progressive, and bilateral, generally symmetric. Some of them may have faculty enzyme or some other bio-chemical defect. Most of the conditions are not preventable and do not have effective treatment.

Degenerations are generally acquired, secondary to infection, inflammation and trauma, may be unilateral, may be prevented by directing treatment towards the primary cause and are non-hereditary.

The retinal dystrophies are a group of disorders that are difficult to classify. Some of them are more common i.e. retinitis pigmentosa than others.

Most useful classification is on the basis of layers of retina involved: 1. Photo receptor dystrophy

(i) Rod and rod-cone dystrophy (ii) Cone and cone-rod dystrophy

(a) Progressive cone dystrophy Type I and type II

(b) Stationary cone dystrophy (c) Cone monochromatism.

2. Ganglion cell dystrophies

(i) Cherry red spots

(ii) Pigmentary dystrophies

(a) Fundus flavi maculatous (b) Stargards disease

(c) Vitelliform dystrophy (d) Dominant drusen

Other less common dystrophies are Kandori syndrome and dominant progressive dystrophy.

3. Bruch’s membrane dystrophies

(a). Sorsby pseudo inflammatory dystrophy

(b) Disciform degeneration of macula (not a true dystrophy) (c) Angioid streak

Some of the dystrophies, which are altogether different from the above condition also involve vitreous and are known as vitreo retinal dystrophies. They include:

1.Juvenile retinochisis

2.Wagners vitreoretinal dystrophy

3.Familial exudative vitreoretinal dystrophy

4.Goldmann -Favre vitreoretinal dystrophy

Out of all the conditions listed above (all are not seen in childhood, very few are seen in first decade), the most common disorder is rod and rod cone dystrophy where rods are affected, predominantly involvement of cone is less marked and of late onset. They are generally known as retinitis pigmentosa and allied conditions. Again the term retinitis is a misnomer because there is no evidence of inflammatory process in the condition. It is better to call the condition as primary neuro sensory dystrophy of the retina or simply primary retinal dystrophy.

The conditions in the group can be:

1.Typical retinitis pigmentosa

2.Variation of retinitis pigmentosa

3.Retinitis pigmentosa associated with other ocular disorders - Myopia, chronic simple glaucoma, keratoconus

4.Retinitis pigmentosa with systemic involvement

Retinitis pigmentosa54,55,56

This is commonest of all hereditary retinal dystrophies. It is seen among all races with equal distribution all over the world with pockets of large numbers in communities where consanguinity is common. It is seen both in boys as well as girls. Boys are more affected than girls. Women are generally the carrier in X linked diseases. They may be asymptomatic or may have mild symptoms, however fully developed retinitis pigmentosa is not exception in carriers.

The condition is mostly hereditary, however sporadic cases are also known. Sporadicity is due to sudden mutation of genes. There are about twenty genes that have been blamed for the disease. There are about hundred possible mutations. The sporadic cases are also called isolated cases. They are seen in about 15 to 20 percent cases.

There are three modes of inheritance:

1.Autosomal dominant

2.Autosomal recessive

3.x linked

Autosomal recessive is the commonest form of transmission followed by autosomal dominant i.e. mildest, with late onset but diagnosed early. The x linked is the least common but worst. It is most disabling and progresses fast.

Symptoms

1.Diminished night vision. This is the first symptom developing around ten years of age. It may be seen earlier in some children who may be confused as suffering from vitamin A deficiency and treated as such without any improvement. The night blindness is gradually progressive and becomes worse as the child ages. By third decade the person may be incapacitated in dim light. To begin with the children have prolonged dark adaptation i.e. they take more time to get accustomed to indoor illumination when they come from bright light.

2.Diminished peripheral field. The patient soon becomes aware about his loss of peripheral field. He complains that he has to move his head to see on the periphery. He may bump into others and may find difficulty in negotiating on the road or drive. The end result is greatly reduced peripheral field resulting into a tubular vision as if the patient has been looking down the barrel of a gun. Generally the central part surrounded by scotoma retains good vision for long time.

3.Diminished distant vision. Diminished vision is late to appear unless it is due to myopia which is very common in retinitis pigmentosa. Onset of diminished vision can be due to

(i) Macular lesion. Cystoid macular edema, atrophic maculopathy, cellophane maculopathy

(ii) Lenticular. Posterior sub capsular cataract is the commonest type of lenticular changes in retinitis pigmentosa. However development of central nuclear sclerosis is also frequent.

(iii) Optic nerve. Consecutive optic atrophy is very common in late stage.

(iv) Chronic simple glaucoma. Incidence of chronic simple glaucoma is high in retinitis pigmentosa. Field changes of chronic simple glaucoma when superimposed on that of retinitis pigmentosa worsen each other.

Signs of retinitis pigmentosa

The triad of signs i.e. pigments, attenuation of blood vessels and waxy pale disc are characteristics of retinitis pigmentosa in presence of night blindness.

1.Pigmentary changes. The pigmentary changes are brought about due to migration of pigment from deeper layer. They start in the mid periphery of the retina. In early stages, they are nothing but mottling of retinal pigment with prominence of chorio capillaries. With passage of time bunches of pigment begin to collect round the veins, then they cover all the vessels. Later the pigments become spider shaped or bone spicule like in shape. In the same eye various shapes and sizes of pigment can be seen. The pigments gradually spread centripetal as well as centrifugal but never reach the posterior pole unless it is central type. Affinity of the pigments for mid periphery is not well understood. Most common argument put forward is paucity of blood supply of the mid periphery.

2.Thinning of retinal blood vessels. Though pigmentary changes are more conspicuous than attenuation vessel, the vessel changes may precede the pigmentary changes. The vessels may become thread like in late stages.

3.Optic atrophy is a late feature. The colour of the disc is waxy pale. It may be associated with other abnormalities like drusen, may have subtle glioma of the disc.

4.Error of refraction. About three fourth of eyes with retinitis pigmentosa have myopia of moderate degree.

5.Vitreous opacities are very common in retinitis pigmentosa, myopia may be partly responsible for it. The opacities increase with age.

6.Macular involvement are more common than previously thought to be. Macular changes are being reported more frequently following fluorescein angiography. It may just be a decreased reflex or as serious as cystoid macular edema.

7.Lenticular changes. Posterior sub capsular opacification is the commonest form of lenticular changes. It may be seen as early as ten to fifteen years of age. The incidence increases loss of central vision due to posterior sub capsular opacification. Posterior polar cataract add to the misery of the patient who already has a very narrow field.

8.Chronic simple glaucoma is seen in a small percentage of cases in third and fourth decade.

9.Other ocular findings are—Keratoconus, squint, progressive external ophthalmioplegia and rarely microphthalmos.

Variants of a typical retinitis pigmentosa

The triad for diagnosis of retinitis pigmentosa are bilateral annular pigmentation in mid periphery, attenuation of retinal vessels, waxy pale disc with diminished vision. In some cases the pigmentation is unilateral or just sectorial. Sometimes night blindness may precede pigmentation or there may be white dots in the periphery with night blindness. In rarer cases the involvement of the posterior pole is disproportionate to peripheral lesion. All these conditions are called atypical form of retinitis pigmentosa. Some authors are of opinion that these cases except those with white dots will culminate into typical retinitis pigmentosa. The common forms are: