This refers to acute or chronic intraocular inflammation due to microbial or immunologic causes. In the strict sense, any intraocular inflammation is endophthalmitis. However, in clinical usage and throughout this book, endophthalmitis refers only to inflammation caused by a microbial action that also involves the vitreous body (vitritis). On the other hand, isolated vitritis without involvement of the other intraocular structures is inconceivable due to the avascularity of the vitreous chamber.
— Forms of vitreous hemorrhage. -
Epidemiology: Microbial vitritis or endophthalmitis occurs most frequently as a result of penetrating trauma to the globe. Rarely (in 0.5 % of all cases) it is a complication of incisive intraocular surgery.
Etiology: Because the vitreous body consists of only a few cellular elements (hyalocytes), inflammation of the vitreous body is only possible when the inflammatory cells can gain access to the vitreous chamber from the uveal tract or retinal blood vessels. This may occur via one of the following mechanisms:
❖ Microbial pathogens, i.e., bacteria, fungi, or viruses, enter the vitreous chamber either through direct contamination (for example via penetrating trauma or incisive intraocular surgery) or metastatically as a result of sepsis. The virulence of the pathogens and the patient's individual immune status determine whether an acute, subacute, or chronic inflammation will develop. Bacterial inflammation is far more frequent than viral or fungal inflammation. However, the metastatic form of endophthalmitis is observed in immunocompromised patients. Usually the inflammation is fungal (mycotic endophthalmitis), and most often it is caused by one of the Candida species.
❖ Inflammatory (microbial or autoimmune) processes, in structures adjacent to the vitreous body, such as uveitis or retinitis can precipitate a secondary reaction in the vitreous chamber.
Acute endophthalmitis is a serious clinical syndrome that can result in loss of the eye within a few hours.
Symptoms: Acute vitreous inflammation or endophthalmitis. Characteristic symptoms include acute loss of visual acuity accompanied by deep dull ocular pain that responds only minimally to analgesic agents. Severe reddening of the conjunctiva is present. In contrast to bacterial or viral endophthal-mitis, mycotic endophthalmitis begins as a subacute disorder characterized by slowly worsening chronic visual impairment. Days or weeks later, this will also be accompanied by severe pain.
Chronic vitreous inflammation or endophthalmitis. The clinical course is far less severe, and the loss of visual acuity is often moderate.
Diagnostic considerations: The patient's history and the presence of typical symptoms provide important information.
Acute vitreous inflammation or endophthalmitis. Slit-lamp examination will reveal massive conjunctival and ciliary injection accompanied by hypopyon (collection of pus in the anterior chamber). Ophthalmoscopy will reveal yellowish-green discoloration of the vitreous body occasionally referred to as a vitreous body abscess. If the view is obscured, ultrasound studies can help to evaluate the extent of the involvement of the vitreous body in endophthalmitis. Roth's spots (white retinal spots surrounded by hemor-
rhage) and circumscribed retinochoroiditis with a vitreous infiltrate will be observed in the initial stages (during the first few days) of mycotic endophthalmitis. In advanced stages, the vitreous infiltrate has a creamy whitish appearance, and retinal detachment can occur.
Chronic vitreous inflammation or endophthalmitis. Inspection will usually reveal only moderate conjunctival and ciliary injection. Slit-lamp examination will reveal infiltration of the vitreous body by inflammatory cells.
A conjunctival smear, a sample of vitreous aspirate, and (where sepsis is suspected) blood cultures should be obtained for microbiological examination to identify the pathogen. Negative microbial results do not exclude possible microbial inflammation; the clinical findings are decisive. See Chapter 12 for diagnosis of retinitis and uveitis.
Differential diagnosis: The diagnosis is made by clinical examination in most patients. Intraocular lymphoma should be excluded in chronic forms of the disorder that fail to respond to antibiotic therapy.
Treatment: Microbial inflammations require pathogen-specific systemic, topical, and intravitreal therapy, where possible according to the strain's documented resistance to antibiotics. Mycotic endophthalmitis is usually treated with amphotericin B and steroids. Immediate vitrectomy is a therapeutic option whose indications have yet to be clearly defined.
Secondary vitreous reactions in the presence of underlying retinitis or uveitis should be addressed by treating the underlying disorder.
Prophylaxis: Intraocular surgery requires extreme care to avoid intraocular contamination with pathogens. Immunocompromised patients (such as AIDS patients or substance abusers) and patients with indwelling catheters should undergo regular examination by an ophthalmologist.
H Decreased visual acuity and eye pain in substance abusers and patients with indwelling catheters suggest Candida endophthalmitis.
Clinical course and prognosis: The prognosis for acute microbial endophthalmitis depends on the virulence of the pathogen and how quickly effective antimicrobial therapy can be initiated. Extremely virulent pathogens such as Pseudomonas and delayed initiation of treatment (not within a few hours) worsen the prognosis for visual acuity. With postoperative inflammation and poor initial visual acuity, an immediate vitrectomy can improve the clinical course of the disorder. The prognosis is usually far better for chronic forms and secondary vitritis in uveitis/vitritis.
11.5 TheRoleoftheVitreousBodyinVariousOcularChanges 293 11.4.5 Vitreoretinal Dystrophies
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