Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmology A Systematic Approach 7th Edition_Kanski, Bowling_2011

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Fig. 15.16 ERGin progressive cone dystrophy shows reduced photopic responses and flicker fusion frequency

Fig. 15.17 Bull's eye maculopathy. (A and B) Clinical appearance; (C and D) appearance on FA

Leber congenital amaurosis

Leber congenital amaurosis is a severe rod-cone dystrophy that is the commonest genetic cause of visual impairment in infants and

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children. It carries a very poor prognosis.

1Inheritance is usually AR. It is genetically heterogeneous, with at least 14 gene loci identified.

2Presentation is with blindness at birth, or shortly thereafter, associated with roving eye movements or nystagmus.

3Signs are variable and include the following:

•The pupillary light reflexes are absent or diminished.

•The fundi may be normal initially apart from mild arteriolar narrowing.

•Mild peripheral pigmentary retinopathy (Fig. 15.18A), salt and pepper changes, and less frequently yellow flecks.

•Severe macular pigmentation (Fig. 15.18B) or coloboma-like atrophy (Fig. 15.18C).

•Pigmentary retinopathy, optic atrophy and severe arteriolar narrowing in later childhood.

•Disc elevation is uncommon.

•Oculodigital syndrome in which constant rubbing of the eyes by the child causes enophthalmos as the result of atrophy of orbital fat (Fig. 15.18D).

4 Ocular associations include strabismus, hypermetropia, keratoconus, keratoglobus and cataract.

5ERG is usually non-recordable even in early cases with normal-appearing fundi.

6Systemic associations include mental handicap, deafness, epilepsy, CNS and renal anomalies, skeletal malformations and endocrine dysfunction.

Fig. 15.18 Leber congenital amaurosis. (A) Mild pigmentary retinopathy; (B) macular pigmentation and optic disc drusen; (C) macular coloboma-like atrophy; (D) oculodigital syndrome

(Courtesy of A Moore – figs A-C; N Rogers – fig. D)

Stargardt disease and fundus flavimaculatus

Stargardt disease (juvenile macular dystrophy) and fundus flavimaculatus (FFM) are regarded as variants of the same disease despite presenting at different times and carrying different prognoses. The condition is characterized by diffuse accumulation of lipofuscin within the RPE that results in vermilion fundus and a ‘dark choroid’ seen on FA (see below).

1Inheritance is AR. Mutations in at least three different genes have been identified as causing Stargardt disease, including ABCA4, and at least two, again including ABCA4, for FFM.

2Presentation is in the 1st–2nd decades with bilateral gradual impairment of central vision which may be out of proportion to the macular changes, so that the child may be suspected of malingering. Some patients present in adult life, although in the absence of macular involvement the condition may remain asymptomatic for many years and discovered by chance.

3Macula may show the following:

•May be initially normal or show non-specific mottling (Fig. 15.19A).

•An oval ‘snail-slime’ or ‘beaten-bronze’ appearance (Fig. 15.19B).

•Geographic atrophy that may have a bull's eye configuration (Fig. 15.19C).

4Flecks have the following characteristics;

•Bilateral yellow-white lesions at the level of the RPE; of various size and shape, such as round, oval or pisciform (fishshaped).

•Distribution may be at the posterior pole exclusively or extending to the mid-periphery (Fig. 15.19D).

•New lesions develop as older ones become ill-defined and softer.

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5Prognosis of maculopathy is poor; once visual acuity drops below 6/12 it tends to decrease rapidly and stabilize at about 6/60. Patients with only flecks have a relatively good prognosis and may remain asymptomatic for many years until the development of macular disease. A small minority develop CNV which carries a very poor prognosis.

6 ERG. Photopic is normal to subnormal and scotopic is normal.

7EOG is subnormal in advanced cases.

8FA

•Maculopathy shows hyperfluorescence due to a window defect often associated with a generalized ‘dark choroid’ with prominence of the retinal vasculature (Fig. 15.20A).

•Fresh flecks show early hypofluorescence due to blockage and late hyperfluorescence due to staining; old flecks show RPE window defects (Fig. 15.20B).

9 ICGA shows hypofluorescent spots (Fig. 15.20C).

10 Autofluorescence may be present (Fig. 15.20D).

Fig. 15.19 Stargardt disease/fundus flavimaculatus. (A) Nonspecific macular mottling; (B) ‘snail slime’ maculopathy surrounded by flecks; (C) bull's eye maculopathy surrounded by flecks; (D) diffuse flecks

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Fig. 15.20 Imaging in Stargardt disease/fundus flavimaculatus. (A) FA shows macular hyperfluorescence and a ‘dark’ choroid; (B) FA shows hyperfluorescent spots; (C) ICGA shows hypofluorescent spots

(Courtesy of A Bolton – fig. C)

Bietti corneoretinal crystalline dystrophy

Bietti dystrophy is characterized by deposition of crystals in the retina and the superficial peripheral cornea. It is much more common in East Asians, particularly Chinese, than other ethnicities.

1Inheritance is AR with the gene locus on 4q35 (CYP4VZ gene).

2Presentation is in the 3rd–4th decades with slowly progressive visual loss.

3Signs in chronological order:

•Numerous, fine, glistening, yellow-white crystals, located in all layers of the retina, scattered throughout the posterior fundus (Fig. 15.21A).

•Localized atrophy of the RPE and choriocapillaris at the macula.

•Diffuse atrophy of the choriocapillaris with a decrease in size and number of the crystals.

•Gradual confluence and expansion of the atrophic areas into the periphery.

•Diffuse chorioretinal atrophy in end-stage disease.

4ERG is subnormal.

5 FA shows characteristic large hypofluorescent patches with intact overlying retinal vessels (Fig. 15.21B). 6 Prognosis is variable because the rate of disease progression differs in individual cases.

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Fig. 15.21 (A) Bietti corneoretinal crystalline dystrophy; (B) FA shows hypofluorescent patches

Alport syndrome

1Pathogenesis. Alport syndrome is a rare abnormality of glomerular basement membrane caused by mutations in several different genes, all of which encode particular forms of type IV collagen, a major component of basement membrane. It is characterized by chronic renal failure, often associated with sensorineural deafness.

2Inheritance is predominantly XL.

3Signs

•Scattered, yellowish, punctate flecks in the perimacular area with normal visual acuity (Fig. 15.22A).

•Larger peripheral flecks, some of which may become confluent (Fig. 15.22B).

4ERG is normal.

5 Ocular associations are anterior lenticonus and occasionally posterior polymorphous corneal dystrophy. 6 Prognosis for vision is excellent.

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Fig. 15.22 Alport syndrome. (A) Perimacular flecks; (B) peripheral flecks

(Courtesy of J Govan)

Familial benign fleck retina

Familial benign fleck retina is a very rare disorder which is asymptomatic and therefore usually discovered by chance.

1Inheritance is AR.

2 Signs. Widespread, discrete, yellow-white, polymorphous shapes which spare the fovea and extend to the far periphery (Fig. 15.23).

3ERG is normal.

4Prognosis is excellent.

Fig. 15.23 Benign familial fleck retina

Pigmented paravenous chorioretinal atrophy

Paravenous chorioretinal atrophy is an innocuous and asymptomatic condition that is usually non-progressive. The fundus changes are

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bilaterally symmetric.

1Inheritance is predominantly AD and can be caused by mutations in the CRB1 gene (lq31–q).

2Signs

•Sharply outlined zones of chorioretinal atrophy that follow the course of the major retinal veins and may also encircle the optic disc.

•Paravenous bone-spicule pigmentation (Fig. 15.24).

•Optic disc and retinal vascular calibre are usually normal.

3ERG is normal.

Fig. 15.24 Pigmented paravenous retinochoroidal atrophy

(Courtesy of C Barry)

Congenital stationary night blindness

Congenital stationary night blindness (CSNB) refers to a group of disorders characterized by infantile onset nyctalopia and non-progressive retinal dysfunction. The fundus appearance may be normal or abnormal.

With normal fundus

CSNB with a normal fundus appearance is sometimes classified into type 1 (complete) and type 2 (incomplete) forms. The former is characterized by complete absence of rod pathway function and essentially normal cone function clinically and on ERG, the latter has impairment with both rod and cone function. Mutations in numerous genes have been identified as causing the CSNB phenotype, with XL, AD and AR inheritance patterns.

With abnormal fundus

1Oguchi disease is a very rare AR condition.

•The fundus has an unusual golden-yellow colour in the light-adapted state (Fig. 15.25A) which becomes normal after prolonged dark adaptation (Mizuo phenomenon – Fig 15.25B).

•Rod function is absent after 30 minutes of dark adaptation but recovers to a near-normal level after a long period of dark adaptation.

2Fundus albipunctatus is an innocuous AR or AD condition.

•The fundus shows a multitude of subtle, tiny yellow-white spots at the posterior pole, sparing the fovea and extending to the periphery (Fig. 15.26A).

•The retinal blood vessels, optic disc, peripheral fields and visual acuity remain normal.

•FA shows mottled hyperfluorescence, except at the fovea, indicating depigmentation of the RPE (Fig. 15.26B).

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Fig. 15.25 Mizuo phenomenon in Oguchi disease. (A) In the light-adapted state; (B) in the dark-adapted state

(Courtesy of J Donald M Gass, from Stereoscopic Atlas of Macular Diseases, Mosby, 1997)

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Fig. 15.26 Fundus albipunctatus. (A) Clinical appearance; (B) FA shows mottled hyperfluorescence

(Courtesy of C Barry)

Congenital monochromatism (achromatopsia)

Rod monochromatism (complete achromatopsia)

1 Inheritance is AR.

2Signs

•VA is 6/60.

•Macula usually appears normal but may be hypoplastic.

•Congenital nystagmus and photophobia.

3 ERG. Photopic abnormal; scotopic may be subnormal; flicker fusion <30HZ. 4 CV is totally absent, all colours appearing as shades of grey.

Blue cone monochromatism (incomplete achromatopsia)

1 Inheritance is XL.

2Signs

•VA is 6/6–6/9.

•Normal macula.

•Nystagmus and photophobia are absent.

3 ERG is normal except for absence of cone responses to red and white light. 4 CV is totally absent.

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Macular dystrophies

Juvenile Best macular dystrophy

Best (vitelliform) macular dystrophy is the second most common macular dystrophy.

1 Inheritance is AD with variable penetrance and expressivity with the gene locus on 11q13 (BEST1 gene).

2Signs evolve gradually through the following stages:

aPre-vitelliform is characterized by a subnormal EOG in an asymptomatic child with a normal fundus.

bVitelliform develops in infancy or early childhood and does not usually impair vision.

•A round, sharply-delineated (‘sunny side up egg yolk’) macular lesion within the RPE that varies in size between half a disc and two disc diameters (Fig. 15.27A).

•FA shows corresponding hypofluorescence due to blockage (Fig. 15.27B).

•OCT shows material within the RPE (Fig. 15.27C).

•The size of the lesions and stage of development in the two eyes may be asymmetrical and occasionally only one eye is initially involved.

•Occasionally the condition may be extramacular and multiple (Fig. 15.27D).

cPseudohypopyon may occur at puberty when part of the lesion becomes resorbed (Fig. 15.27E).

d Vitelliruptive in which the egg yolk begins to break up ('scramble’) and visual acuity drops (Fig. 15.27F).

eAtrophic in which all pigment has disappeared leaving an atrophic area of RPE.

3EOG is severely subnormal during all stages and also abnormal in carriers with normal fundi.

4Prognosis is reasonably good until the 5th decade after which visual acuity declines in one or both eyes due to CNV, scarring or geographic atrophy.

Fig. 15.27 Juvenile Best macular dystrophy. (A) Vitelliformstage; (B) FA shows hypofluorescence due to blocked background choroidal fluorescence; (C) OCT shows material within the RPE; (D) multifocal disease; (E) pseudohypopyon stage; (F) vitelliruptive stage

(Courtesy of C Barry – fig. C)

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