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

kanski 7th

•Mid-peripheral depigmented spots associated with diffuse pigmentary mottling may be seen in asymptomatic cases.

•Sharply-demarcated circular or oval areas of chorioretinal atrophy that may be associated with numerous glistening crystals at the posterior pole (Fig. 15.41A).

•Coalescence of atrophic areas and gradual peripheral and central spread (Fig. 15.41B).

•The fovea is spared until late (Fig. 15.41C).

•Extreme attenuation of retinal blood vessels.

•Vitreous degeneration and early-onset cataracts are common.

4 FA shows sharp demarcation between the choroidal atrophy and normal filling of the choriocapillaris.

5ERG is subnormal is early disease and later becomes extinguished.

6Treatment. There are two clinically different subtypes of gyrate atrophy based on response to pyridoxine (vitamin B6), which may normalize plasma and urinary ornithine levels. Patients who are responsive to vitamin B6 generally have a less severe and more slowly progressive clinical course than those who are not. Reduction in ornithine levels with an arginine-restricted diet is also beneficial.

7Prognosis is generally poor with legal blindness occurring in the 4th–6th decades from geographic atrophy, although vision may fail earlier due to cataract, CMO or epiretinal membrane formation.

Fig. 15.41 Gyrate atrophy. (A) Early disease; (B) advanced disease; (C) end-stage disease with preservation of the fovea

Generalized choroidal dystrophy

1Inheritance is AD.

2Presentation is in the 4th–5th decades with central visual loss or nyctalopia.

3Signs

•Mild pigment mottling at the posterior pole followed by atrophy of the RPE and choriocapillaris.

•Severe chorioretinal atrophy that spreads gradually and until it involves virtually the entire fundus (Fig. 15.42).

4ERG is subnormal.

5 Prognosis is poor because of early macular involvement.

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Fig. 15.42 Generalized choroidal dystrophy

Progressive bifocal chorioretinal atrophy

1 Inheritance is AD with the gene locus on 6q.

2Presentation is at birth.

3Signs in chronological order

•A focus of chorioretinal atrophy temporal to the disc which extends in all directions.

•A similar lesion develops nasally.

•The end result manifests two separate areas of chorioretinal atrophy separated by a normal segment (Fig. 15.43).

4Prognosis is poor because macular involvement is inevitable.

Fig. 15.43 Progressive bifocal chorioretinal atrophy

(Courtesy of Moorfields Eye Hospital)

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Vitreoretinal dystrophies

Juvenile X-linked retinoschisis

Pathogenesis

Juvenile retinoschisis is characterized by bilateral maculopathy, with associated peripheral retinoschisis in 50% of patients. The basic defect is in the Müller cells, causing splitting of the retinal nerve fibre layer from the rest of the sensory retina. This differs from acquired (senile) retinoschisis in which splitting occurs at the outer plexiform layer.

Diagnosis

1Inheritance is XL with the implicated gene designated RS1 on Xp22.1-22.2.

2Presentation is between the ages of 5–10 years with reading difficulties due to maculopathy. Less frequently the disease presents in infancy with squint or nystagmus associated with advanced peripheral retinoschisis, often with vitreous haemorrhage.

3Foveal schisis

•‘Bicycle wheel’ radial striae radiating from the foveola associated with cystoid macular changes (Fig. 15.44A).

•Over time the striae become less evident leaving a blunted foveal reflex.

4Peripheral schisis predominantly involves the inferotemporal quadrant. It does not extend but may undergo the following secondary changes:

•The inner layer, which consists only of the internal limiting membrane and the retinal nerve fibre layer, may develop oval defects (Fig. 15.44B).

•In extreme cases, the defects coalesce, leaving only retinal blood vessels floating in the vitreous (‘vitreous veils’) (Fig. 15.44C).

•Peripheral silver dendritic figures (Fig. 15.44D), vascular sheathing and pigmentary changes are common.

•Nasal dragging of retinal vessels and retinal flecks may be seen.

5Complications include vitreous and intra-schisis haemorrhage, neovascularization, subretinal exudation (Fig. 15.45A), and rarely retinal detachment and traumatic rupture of foveal schisis (Fig. 15.45B).

6Prognosis is poor due to progressive maculopathy. Visual acuity deteriorates during the first two decades and may remain stable until the 5th–6th decades when further deterioration occurs.

7OCT is useful for documenting progression of maculopathy (Fig. 15.46).

8ERG is normal in eyes with isolated maculopathy. Eyes with peripheral schisis show a characteristic selective decrease in amplitude of the b-wave as compared with the a-wave on scotopic and photopic testing (Fig. 15.47).

9 EOG is normal in eyes with isolated maculopathy but subnormal in eyes with advanced peripheral lesions. 10 FA of maculopathy may show mild window defects but no leakage.

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Fig. 15.44 Juvenile retinoschisis. (A) ‘Bicycle wheel’-like maculopathy; (B) inner leaf defect; (C) ‘vitreous veils’; (D) peripheral dendritic lesions

(Courtesy of K Slowinski – fig. A; C Barry – figs B and C; Moorfields Eye Hospital – fig. D)

Fig. 15.45 Complications of juvenile retinoschisis. (A) Traumatic hole in macular schisis; (B) subretinal exudation

(Courtesy of K Slowinski – fig. A; G-M Sarra – fig. B)

Fig. 15.46 OCTof macular schisis shows cyst-like changes

(Courtesy of J Talks)

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Fig. 15.47 ERGin peripheral juvenile retinoschisis shows selective decrease of the b-wave amplitude

Stickler syndrome

Stickler syndrome (hereditary arthro-ophthalmopathy) is a disorder of collagen connective tissue. Inheritance is AD with complete penetrance but variable expressivity. Stickler syndrome is the commonest inherited cause of retinal detachment in children.

Classification

1STL1 is the most common, maps to 12q13.11-q13.2, and is the result of mutations in the COL2A1 gene. These subjects have the classic ocular and systemic features as originally described by Stickler.

2STL2 maps to 1p21 and is caused by mutations in the COL11A1 gene. These subjects have congenital non-progressive high myopia, sensorineural deafness, and other features of Stickler syndrome type 1.

3STL3 maps to 6p21.3 and is due to mutations in the COL11A2 gene. These subjects have the typical systemic features, but no ocular manifestations.

Systemic features

1Facial anomalies include mid-facial hypoplasia, depressed nasal bridge, short nose, anteverted nares and micrognathia (Fig. 15.48A).

2Oral anomalies include cleft and high-arched palate (Fig. 15.48B), and bifid uvula.

3Skeletal involvement includes relatively mild spondyloepiphyseal dysplasia, and joint hypermobility that decreases with age but may be followed by osteoarthritis in the 3rd–4th decades. Occasional findings include slender extremities with arachnodactyly that must not be confused with Marfan syndrome.

4 Deafness that may be caused by recurrent otitis media or due to sensorineural defect.

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Fig. 15.48 Stickler syndrome. (A) Facial appearance; (B) cleft and high-arched palate

(Courtesy of K Nischal – fig. B)

Ocular features

1Presentation is in early childhood with high non-progressive myopia.

2Signs

•In STL1 patients exhibit an optically empty vitreous, a retrolenticular membrane and circumferential equatorial membranes that extend a short way into the vitreous cavity (membranous type 1 vitreous – Fig. 15.49A).

•In STL2 patients the vitreous has a fibrillary and beaded appearance (fibrillary type 2 vitreous).

•Radial lattice-like degeneration associated with RPE hyperplasia, vascular sheathing and sclerosis (Fig. 15.49B).

•Retinal detachment develops in approximately 50% in the first decade of life, often as a result of multiple or giant tears that may involve both eyes.

•Regular screening is mandatory so that retinal breaks can be treated prophylactically.

3Associations

aPresenile cataract characterized by frequently non-progressive peripheral cortical ‘wedge’ or ‘fleck’ opacities is common.

bEctopia lentis is uncommon.

c Glaucoma occurs in 5–10% of cases and is associated with a congenital angle anomaly.

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Fig. 15.49 Stickler syndrome. (A) Vitreous liquefaction and membranes; (B) radial lattice degeneration and pigmentary changes

Wagner syndrome

Wagner syndrome (erosive vitreoretinopathy) shows similar vitreous changes to Stickler syndrome but is not associated with systemic abnormalities.

1Inheritance is AD with the gene locus on 5q12-q14.

2Presentation is in early life with pseudostrabismus due to congenital temporal displacement of the fovea with a positive angle kappa, and nyctalopia.

3Signs

•Low myopia (−3.00 or less).

•The vitreous is optically empty with complete absence of normal scaffolding (Fig. 15.50A).

•Avascular greyish-white preretinal membranes extending from the posterior pole to the periphery (Fig. 15.50B).

•Progressive chorioretinal atrophy (Fig. 15.50C)

4FA shows non-perfusion due to gross loss of the choriocapillaris (Fig. 15.50D).

5ERG may initially be normal and then shows reduction of scotopic b-wave amplitudes and diffuse cone-rod loss.

6Complications include cortical cataracts in the 4th decade, peripheral tractional retinal detachment in about 50% of patients older than 45 years of age, and occasionally glaucoma.

7 Prognosis is poor.

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Fig. 15.50 Wagner syndrome. (A) Vitreous liquefaction; (B) peripheral chorioretinal atrophy and preretinal membranes; (C) progressive chorioretinal atrophy; (D) FA shows gross loss of the choriocapillaris

(Courtesy of E Messmer)

Familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy (Criswick–Schepens syndrome) is a slowly-progressive condition characterized by failure of vascularization of the temporal retinal periphery, similar to that seen in retinopathy of prematurity, but not associated with low birth weight and prematurity.

1 Inheritance is AD and rarely XLR or AR, with high penetrance and variable expressivity.

2Presentation is in late childhood.

3Signs

•Vitreous degeneration and peripheral vitreoretinal attachments associated with areas of ‘white without pressure’.

•Abrupt termination of peripheral retinal vessels in a scalloped pattern at the temporal equator.

•Peripheral vascular tortuosity, telangiectasia (Fig. 15.51A) and neovascularization.

•Fibrovascular proliferation and vitreoretinal traction resulting in ridge formation (Fig. 15.51B).

•Progressive peripheral fibrovascular proliferation (Fig. 15.51C)

•Vascular straightening and temporal ‘dragging’ of the macula and disc (Fig. 15.51D).

4Complications include tractional retinal detachment during the first decade, subretinal exudation that may become massive (Fig. 15.51E), vitreous haemorrhage, cataract and neovascular glaucoma.

5 FA shows peripheral retinal non-perfusion and highlights straightening of blood vessels (Fig. 15.51F).

6Prognosis is poor although in some cases peripheral retinal laser photocoagulation or cryotherapy may be beneficial. Vitreoretinal surgery for retinal detachment, whilst difficult, may be successful in selected cases.

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Fig. 15.51 Familial exudative vitreoretinopathy. (A) Peripheral telangiectasia; (B) fibrovascular ridge; (C) fibrovascular proliferation; (D) ‘dragging’ of the disc and macula; (E) subretinal exudation; (F) FA shows vascular straightening and abrupt termination

(Courtesy of C Hoyng – fig. E)

Enhanced S-cone syndrome and Goldmann–Favre syndrome

There appears to be an overlap between these two conditions, and it is believed that the latter may represent a more severe variant of the former.

1 Inheritance is AR with variable expressivity. The gene implicated is NR2E3 at 15q23.

2Presentation is with nyctalopia in childhood.

3Signs

•Pigmentary changes along the vascular arcades or mid-periphery that may be associated with round pigment clumps in more advanced case (Fig. 15.52A)

•Cystoid maculopathy without fluorescein leakage, or schisis (Fig. 15.52B).

•Vitreous degeneration and peripheral retinoschisis in Goldmann–Favre.

4ERG. The human retina has three cone photoreceptor types: short-wave sensitivity (S-), middle-wave sensitivity (M-) and long-wave sensitivity (L-). Most inherited retinal dystrophies exhibit progressive attenuation of rods and all classes of cones. However, enhanced S-cone syndrome is unique because it is characterized by hyperfunction of S-cones and severe impairment of M- and L- cones, and non-recordable rod functions.

5 Prognosis is poor because the condition is progressive.

6Differential diagnosis.

•Retinitis pigmentosa.

•Congenital retinoschisis.

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Fig. 15.52 Enhanced S-cone and Goldmann–Favre syndrome. (A) Severe pigment clumping; (B) macular schisis and pigmentary changes along the arcade

(Courtesy of D Taylor and CS Hoyt, from Pediatric Ophthalmology and Strabismus, Elsevier Saunders 2005 – fig. A; J Donald M Gass, from Stereoscopic Atlas of Macular Diseases, Mosby 1997 – fig. B)

Snowflake vitreoretinal degeneration

1Inheritance is AD with the gene locus on 2q37.

2Signs (Fig. 15.53)

•Stage 1 shows extensive areas of ‘white-without-pressure’ in patients under the age of 15 years.

•Stage 2 shows snowflake-like, yellow-white spots in areas of ‘white with pressure’ in patients between 15 and 25 years.

•Stage 3 manifests vascular sheathing and pigmentation posterior to the area of snowflake degeneration in patients between 25 and 50 years.

•Stage 4 is characterized by increased pigmentation, gross vascular attenuation, areas of chorioretinal atrophy, and less prominent snowflakes in patients over the age of 60 years. The macula and disc remain normal.

•Other signs include mild myopia, vitreous fibrillary degeneration and liquefaction, a dysmorphic optic nerve head and corneal guttae.

4 Complications include retinal break formation, retinal detachment and presenile cataract. 5 ERG shows low scotopic b-wave amplitude.

6 Prognosis is usually good.

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