been advocated. Antibiotics that seem to be effective in treatment include rifampicin, ciprofloxacin, amoxacillin, and tetracycline [403–406]. Patients may have a good visual outcome even without treatment [400].

16.7  Fungal Disease

Fungi are an important group of ubiquitous microorganisms that can cause systemic and ocular disease in humans. Most fungi infect immunocompromised hosts though some are capable of producing disease in immunocompetent hosts. With the AIDS epidemic, fungi are playing an increasing role in the causation of systemic and ocular disease. Endogenous fungal endophthalmitis is of particular pediatric importance, particularly in newborns and infants. Prematurity and low birth weight are important risk factors. Other risk factors accounting for an increase in cases of ocular fungal infection include concurrent antibiotic use and immunosuppression. In this section, we discuss important exogenous and endogenous fungal infections that can affect the pediatric population.

16.7.1  Histoplasmosis

Histoplasma capsulatum is a dimorphic unencapsulated fungus endemic in central and South Eastern United States, Puerto Rico and parts of Central America, Asia, Italy, Turkey, and Australia [407]. The incidence of positive histoplasmin skin test is higher in ocular histoplasmosis syndrome (93%) than in other causes of uveitis (25%) [408, 409]. In Walkersville Maryland, the incidence of positive histoplasmin skin test among 842 persons examined was 59% whereas all patients with ocular histoplasmosis syndrome had positive histoplasmin skin test [410]. A large percentage of patients with OHS have the histocompatibility antigen (HLA B7) [411].

Ocular infection with histoplasma capsulatum may manifest in two ways. In an immunocompetent host, a condition known as presumed ocular histoplasmosis syndrome (POHS) may occur. In the immunocompromised host, acute granulomatous uveitis or panophthalmitis may develop. The later will be discussed under endogenous fungal endophthalmitis.

16.7.1.1  Ocular Histoplasmosis Syndrome (OHS)

Histoplasmosis is known to cause a characteristic syndrome. The characteristic triad of ocular histoplasmosis syndrome consists of histo spots, peripapillary atrophy, and subretinal neovascularization in the posterior pole. “Histo” spots are thought to represent areas of postgranulomatous inflammation from choroidal dissemination of histoplasma capsulatum [412, 413]. They appear as midperipheral small scattered, nonpigmented atrophic areas measuring around 0.5 disc diameters. The lesions are bilateral in 60% of cases [412]. Peripapillary atrophy is a common feature and appears as an atrophic area surrounding the disc inside which a pigmented crescent may be seen (Fig. 16.18). The most serious vision-threatening complication of the disease is development of a choroidal neovascular membrane that may progress to disciform macular scarring (Fig. 16.19a, b). Although disciform macular lesions mostly occur as a late complication at the site of an old atrophic macular scar, de novo subretinal neovascular membranes have been reported [414]. Reactivation of inflammation with enlargement of a preexisting scar or the appearance of new lesion has been reported [415]. It is not clear why subretinal neovascularization has a predilection to the posterior pole; however, the high volume of blood associated with the short posterior ciliary arteries is thought to play a role [416]. Chorioretinal linear streaks, which appear as interlacing hyperpigmented and hypopigmented peripheral scars, have been reported in POHS [417]. The vitreous­ is characteristically clear.

Fig. 16.18  Peripapillary atrophy in ocular histoplasmosis. (Photo courtesy of Peter Buch, University at Buffalo, Ross Eye Institute, Buffalo, NY, USA)