Ординатура / Офтальмология / Английские материалы / Oxford American Handbook of Ophthalmology_Tsai, Denniston, Murray_2011

366 CHAPTER 11 Uveitis

Fungal uveitis

Candidiasis

Candida albicans is a higher-order fungus of the class Blastomycetes. It is yeast-like (i.e., reproduces by budding) and imperfect (i.e., no sexual stage has yet been identified). It is often a commensal of skin, mouth, and vagina, but opportunistic systemic infection may arise from hematogenous spread, notably in intravenous drug abuse, indwelling venous catheters, and immunosuppression.

Uveitis in an intravenous drug abuser should be considered fungal until proven otherwise.

Clinical features

•Risk group: intravenous drug abuse, indwelling catheters (hemodialysis, parenteral nutrition), immunosuppression (AIDS, steroids, cytotoxics, long-term antibiotics), systemic debilitation (malignancy).

•dVA, floaters, pain; often bilateral.

•Multifocal retinitis (yellow-white fluffy lesions 1 DD in size) ± vitritis (colonies appear as “cotton balls” that may be joined together, forming a “string of pearls”) ± anterior uveitis.

•Complications: retinal necrosis, tractional retinal detachment.

Investigation and treatment

•Vitrectomy (send whole vitrectomy cassette) for microscopy/culture to confirm diagnosis.

•Intravitreal antifungals (e.g., 5 μg amphotericin B).

•Systemic antifungals: coordinate care with infectious disease specialist; oral fluconazole (usually 400 mg initially then 200 mg 2x/day) ± flucytosine is generally effective. Consider intravenous amphotericin B (dose according to preparation) for known systemic involvement or resistant cases; duration of treatment is usually 4 weeks.

•Review frequently; hospital admission may be helpful especially if poor adherence or compliance to medical regimen is likely or intravenous treatment is necessary.

Aspergillosis

Aspergillus may occasionally cause an endogenous endophthalmitis similar to Candida. It generally occurs in those with chronic pulmonary disease who are severely immunosuppressed. It is more aggressive than candidal infection, with pain and rapid visual loss being marked.

A confluent yellowish infiltrate is seen in the subretinal space that progresses to a subretinal hypopyon. Other features include intraretinal hemorrhages, dense vitritis, and AC hypopyon. Treatment is similar to Candida but usually requires IV amphotericin B.

FUNGAL UVEITIS 367

Histoplasmosis and POHS

Histoplasma capsulatum is a higher dimorphic fungus that grows as a yeast at 37*C and as a mycelium in soil. It is endemic in southern Europe, southern United States, Central America, and Asia.

Ocular disease from direct infection of the globe is rare, usually occurs in the very young or the immunosuppressed, and may involve posterior or panuveitis or endophthalmitis. Treatment is with ketoconazole or amphotericin B.

More commonly, H. capsulatum is invoked as the possible agent underlying the presumed ocular histoplasmosis syndrome (POHS), albeit via an abnormal immune response. The evidence for H. capsulatum being the causative agent is, however, inconclusive.

Epidemiology indicates that while there is correlation between regions of high prevalence of H. capsulatum and POHS, an apparently identical syndrome is seen in nonendemic areas (such as the UK, northern Europe, and northern US).

The ocular disease is most common in the fourth decade. It is usually bilateral but sequential, with a mean interval of 4 years between onset of symptoms in each eye.

Clinical features

•Well-demarcated atrophic choroidal scars ( 1 DD) around posterior pole/mid-periphery (“histo” spots); peripapillary atrophy; peripheral linear atrophic streaks; no significant vitritis.

•Complications: choroidal neovascularization (type 2); this is often the presenting feature of otherwise asymptomatic disease.

Investigation and treatment

Diagnosis is clinical but FA is required if CNV is suspected. Antifungals have no benefit. Active lesions at the macula are often treated with immunosuppression (commonly corticosteroids).

For extrafoveal and juxtafoveal CNV, conventional laser photocoagulation is of benefit (Macular Photocoagulation Study: severe vision loss at 5 years is 42% for untreated vs. 12% for argon-treated extrafoveal).

For subfoveal membranes, photodynamic therapy (PDT), submacular surgery, and anti-VEGF therapy (membrane excision) should be considered.

368 CHAPTER 11 Uveitis

White dot syndromes (1)

Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)

This is an uncommon condition of young adults that is usually bilateral and may be preceded by a flu-like illness. There appears to be an association with HLA-B7 and HLA-DR2.

Clinical features

•Acute dVA sequentially in both eyes (usually after a few days interval).

•Postequatorial lesions of the RPE (initially gray-white but fade over weeks with irregular depigmentation and pigmentation), mild vitritis.

Figure 11.2 APMPPE lesions of the left eye. Multiple subretinal yellow lesions are in the posterior pole with involvement of the macula. See insert for color version.

370 CHAPTER 11 Uveitis

Investigations and treatment

FA shows early dense hypofluorescence and late staining of lesions. There is spontaneous recovery within 2–3 months, so treatment is not usually indicated.

Serpiginous choroidopathy

This is a rare bilateral condition of the middle-aged patient that may superficially resemble APMPPE but has a much worse prognosis.

Clinical features

•dVA but often asymptomatic until macular involvement.

•Peripapillary lesions at the level of the RPE/inner choroid (gray-white, spread centrifugally from the disc but may skip, becomes atrophic over months with irregular depigmentation and pigmentation), mild vitritis.

•Complications: extensive subretinal scarring, CNV membrane ( 30%).

Investigations and treatment

FA shows early dense hypofluorescence and late staining of lesions. Corticosteroids and other immunosuppressives are commonly used in the acute phase, although there is no clear evidence of benefit.

CNV membranes may be treated by laser, PDT, anti-VEGF therapy, or submacular surgery.

Birdshot retinochoroidopathy (BSRC)

This is an uncommon bilateral condition of middle-aged Caucasian adults, with a slight female preponderance. Around 95% are HLA-A29 positive.

Clinical features

•dVA, dcolor vision, floaters, nyctylopia.

•Lesions at the level of the RPE (oval, cream-colored, radiate from the optic disc to the equator, associated with large choroidal vessels; become atrophic but not pigmented), moderate vitritis, vasculitis, CME.

•Complications: CNV membrane, optic atrophy.

Investigations and treatment

This is one condition in which treatment should be directed by FA and electrodiagnostic results rather than the clinical picture alone.

•ERG: db-wave amplitude and latency; EOG: dArden ratio.

•HLA testing: HLA-A29 positive in 95%. If HLA-A29 negative, consider sarcoid in the differential diagnosis as this can give a similar picture.

Corticosteroids, intravitreal flucinolone implant and other immunosuppressives are used to treat any CME, retinal vasculitis, retinal degenration, with guarded final outcome.

CNV membranes may be treated by laser, PDT, anti-VEGF therapy, or submacular surgery.

More recently, intravenous daclizumab has demonstrated excellent success in controlling disease activity in BSRC.

WHITE DOT SYNDROMES (2) 371

White dot syndromes (2)

Multifocal choroiditis with panuveitis (MCP) and punctate inner choroidopathy (PIC)

These are uncommon bilateral conditions that may simulate POHS (sometimes called pseudo-POHS). Both are more common in women, but PIC tends to affect a younger age group. A viral etiology has been suggested.

Clinical features

•dVA, scotomas, photopsia.

•MCP: choroidal lesions (gray, peripheral + posterior polar), vitritis, anterior uveitis, CME, subretinal fibrosis, CNV membrane.

•PIC: quiet eye (no vitritis) with lesions at the level of the inner choroid or retina (initially yellow-white but become atrophic pigmented scars similar to POHS; posterior polar), serous retinal detachment, CNV membrane.

Investigations and treatment

•FA: early hypofluorescence and late staining of lesions.

•Corticosteroids are commonly used for acute lesions or CME.

•CNV membrane: medical treatment, laser, PDT, anti-VEGF therapy or submacular surgery.

Multiple evanescent white-dot syndrome (MEWDS)

This is a rare unilateral condition, typically in young women, which may be preceded by a flu-like illness.

Clinical features

•Acute dVA, scotomas ± photopsia.

•Small white dots at level of outer retina/RPE, tiny orange-white dots at the fovea, mild vitritis.

Investigations and treatment

•FA: early punctate hyperfluorescence and late staining of lesions.

•ERG: da-wave.

Spontaneous recovery occurs within 2–3 months, so treatment is not usually indicated.

Acute zonal occult outer retinopathy (AZOOR)

This may form part of a spectrum of disease comprising MEWDS, MCP, PIC, and the acute idiopathic blind-spot enlargement syndrome (AIBES). AZOOR is an uncommon condition affecting one or both eyes, typically in myopic young to middle-aged women after a flu-like illness.

Clinical features

•Acute sctomas, worse in bright light; photopsia.

•Acutely may have vitritis; later may have zonal atrophy or irregular pigmentation (RP-like).

372 CHAPTER 11 Uveitis

Investigations and treatment

•ERG: variably abnormal in a patchy distribution and often asymmetric.

•Immunosuppression is common during the acute phase but is of limited proven benefit.

Table 11.24 Summary of white dot syndromes

Vitreoretinal

Anatomy and physiology 374 Retinal detachment: assessment 375 Peripheral retinal degenerations 377 Retinal breaks 379

Posterior vitreous detachment 381 Rhegmatogenous retinal detachment 383 Tractional retinal detachment 385 Exudative retinal detachment 386 Retinoschisis 387

Hereditary vitreoretinal degenerations 389

Choroidal detachments and uveal effusion syndrome 391 Epiretinal membranes 393

Macular hole 395

Laser retinopexy and cryopexy for retinal tears 397 Scleral buckling procedures 399

Vitrectomy: outline 401

Vitrectomy: heavy liquids and tamponade agents 403

374 CHAPTER 12 Vitreoretinal

Anatomy and physiology

Anatomy

Vitreous

The vitreous makes up 80% of ocular volume or around 4.0 mL. It is a transparent gel consisting of hyaluronic acid and collagen (types II, IX, and a V/XI hybrid). Collagen fibrils connect the vitreous to the retinal internal limiting membrane. The vitreous base is a band of adherent vitreous 3–4 mm wide overlying the ora serrata and peripheral retina.

Retina and choroid (p. 406)

The retina is a transparent light-transforming, laminated structure comprising photoreceptors, interneurons, and ganglion cells overlying the retinal pigment epithelium (RPE). Superficial retinal vessels form four major arcades over the surface of the retina.

Within the suprachoroidal space are the long posterior ciliary nerves and arteries, which can be seen peripherally at 3 and 9 o’clock. Similarly, the vortex ampullae (which drain into the vortex veins) may be seen at all four diagonal quadrants just posterior to the equator.

Vitreoretinal adhesions

Normal attachments are strongest at the optic disc, the fovea, and especially the ora serrata/vitreous base, which remains adherent even when posterior vitreous detachment is otherwise complete.

Abnormal attachments include areas of lattice degeneration (posterior border), white without pressure, congenital cystic tufts, pigment clumps, and condensations around retinal vessels.

Physiology

Forces of attachment

The retinal position is maintained by hydrostatic forces and, to a lesser extent, by adhesion of the interphotoreceptor matrix. The hydrostatic forces are both active (the RPE pump) and passive (the osmotic gradient).

Forces of detachment

Vitreoretinal traction may be dynamic (from eye movement) or static (purely from vitreoretinal interaction, e.g., diabetic fibrovascular proliferation). The direction of static forces may be tangential, bridging, or anteroposterior. Gravitational forces are probably a significant factor in superior breaks.

Vitreous liquefaction

The aging vitreous becomes progressively liquefied (syneresis), resulting in optically empty lacunae and a reduction in its shock-absorbing capacity. Liquefaction occurs earlier in myopia, trauma, inflammation, and many disorders of collagen and connective tissue. A break in the cortical vitreous permits vitreal fluid to flow through, causing separation and collapse of the remaining vitreous (posterior vitreous detachment).