Fungal endophthalmitis (FE) is endophthalmitis caused by any of a wide variety of fungal pathogens. Generally, endophthalmitis is an inflammation of the anterior chamber and vitreous (the substance that composes most of the posterior chamber) of the eye and can spread to the retina (the layer of the eye contiguous to the vitreous) and the choroid (the layer behind the retina) (Wu).
Causes
In FE, the fungal infection may be either endogenous, i.e., spread from some other site of fungal infection in the body) or, more commonly, exogenous (acquired directly from outside the body, such as by trauma or at the time of eye surgery). In endogenous FE, the most common organisms are of the Candida species (a yeast type fungus), followed by the Aspergillus species (a mold type fungus). Also seen are infections with Cryptococcus species (a yeast type fungus) and Coccidioides species (a diphasic type fungus) (Essman et al. 185). Predisposing factors to endogenous FE include immunosuppression, intravenous drug abuse, systemic antibiotics, chemotherapy and, especially for Candida species, diabetes mellitus, among others (Klotz et al.). In exogenous FE, Paecilomyces species (a mold type fungus), Acremonium species (a mold type fungus) and Sporothrix species (a diphasic type fungus) are common organisms (Wu).
History
The patient may complain of vision loss, but this symptom may be absent if only the peripheral retina is involved. Eye redness, photophobia (increased sensitivity to light), eye pain, scotomata (blind spots) and vitreal floaters (shadows caused by loose strands of vitreous) may also be seen (Klotz et al. 662).
Physical Findings
Physical findings vary depending upon the offending organism, but generally, examination shows creamy white to yellow chorioretinal lesions with overlying inflammation of the vitreous. Vitreal opacities may be seen. As the disease advances, membranes form next to the retina (epiretinal membranes) causing vitreoretinal traction and retinal detachment. Choroiditis and iridocyclitis may be present, with hypopyon (white cells in the anterior chamber). Candida disease is bilateral in 2/3 of patients (Wu).
Diagnosis
The diagnosis of FE should be suspected when any of the typical eye findings described above is present and there is fungal infection elsewhere in the body. Fungal cultures should be obtained from blood, urine, sputum and cerebrospinal fluid and grown on specialized fungal media (such as Sabouraud or Czapek) and examined after staining with Giemsa, Gomori methenamine-trichrome (GMS) or periodic-acid Schiff (PAS). Because of the fastidious nature of many fungi, cultures may need to be kept for four to six weeks. Growth directly from the eye may be difficult even if a fungus is grown elsewhere (Wu). The highest culture yield from eye tissue is from vitrectomy samples. Polymerase chain reaction (PCR), a method of identifying DNA, may be more sensitive and provide faster results in some cases (Anand 326). Fluorescein angiography (injection of a fluorescent dye) demonstrates hypofluorescence in the early phase and leakage in the later phase. Histology varies according to the fungus involved, but generally shows a granulomatous reaction with acute and chronic inflammatory infiltrates (Wu).
Treatment
Laboratory sensitivity studies against fungi may not correlate well with activity in the human body; therefore, treatment is often empiric. Systemic Amphotericin-B has been the drug of choice for FE, but it penetrates the vitreous poorly and can be quite toxic to the kidneys. It may also be given by direct injection into the vitreous. Fluconazole, ketoconazole and itraconazole have also been used. Vitroconazole, a newer agent, has better penetration of the vitreous. A new class of antifungals called echinocandins, of which caspofungin is an example, acts by inhibiting fungal cell wall synthesis. This class of drugs also has decreased toxicity, since mammalian cells (including human cells) do not have cell walls. (Mora-Duarte et al. 2020).
Surgical treatment with pars plana vitrectomy can also be employed. This procedure can be used to obtain ocular material for culture, to inject antifungals and to remove fungal organisms and inflammatory debris (Zhang and Wang 746).
Outcome
The prognosis of FE is quite variable. Factors include the virulence of the fungus involved, how extensive the eye disease is and how soon and by what route treatment is started. Generally, the prognosis is better with earlier treatment. (Scherer and Lee 1593).
Works Cited
Anand, A., et al. “Use of Polymerase Chain Reaction in the Diagnosis of Fungal
Endophthalmitis.” Ophthalmology 108.2 (2001): 326-30. Print.
Essman, T.F., et al. “Treatment Outcomes in a 10-Year Study of Endogenous Fungal
Endophthalmitis.” Ophthalmic Surgery and Lasers 28.3 (1997): 185-94. Print.
Klotz, S. A., et al. “Fungal and Parasitic Infections of the Eye.” Clinical Microbiology
Review. 13.4 (2000): 662-85. Print.
Mora-Duarte, J., et al. “Comparison of Caspofungin and Amphotericin-B for Invasive
Candidiasis.” New England Journal of Medicine 347.25 (2002): 2020-29. Print.
Scherer, W.J. and K. Lee. “Implications of Early Systemic Therapy on the Incidence of
Endogenous Fungal Endophthalmitis.” Ophthalmology 104.10 (1997): 1593-98. Print.
Wu, Lihteh. “Endophthalmitis, Fungal.” Medscape. 9 Feb. 2010. Web.
24 Feb. 2012.
Zhang, Y. Q. and W.J. Wang. “Treatment outcomes after Pars Plana Vitrectomy
for Endogenous Endophthalmitis.” Retina 25.6 (2005): 746-50. Print.
