Intracorneal rhinosporidiosis managed with deep anterior lamellar keratoplasty.

A healthy 22-year-old male presented to Institutional Cornea Clinic with an intracorneal mass overlying the pupil with lobulated edges having many tiny greyish white dots. The patient had a history of trauma while swimming in a pond with subsequent removal of intracorneal foreign body in the left eye approximately a year prior to presentation. Anterior segment optical coherence tomography (OCT) confirmed that an intracorneal mass sparing deep stroma and Descemet's membrane. A deep anterior lamellar keratoplasty (DALK) was performed in left eye and the mass was sent for histology examination. Histology evaluation was suggestive of rhinosporidiosis. The patient achieved 20/60 BCVA with -1.25 Χ× 120° 1 year postoperatively without any evidence of recurrence at the graft-host interface. This unique presentation (as an 'intracorneal mass') of ocular rhinosporidiosis emphasizes that clinicians from our region of the world must consider rhinosporidiosis in the differential diagnosis especially with a history of penetrating injury while swimming in pond or river water.

Failure of Acanthamoeba castellanii to produce intraocular infections.

PURPOSE: This study examined possible mechanisms to explain why Acanthamoeba castellanii remains restricted to the cornea and rarely produces intraocular infections. The first hypothesis proposed that trophozoites cannot penetrate Descemet's membrane and the corneal endothelium to enter the anterior chamber (AC). The second hypothesis proposed that the trophozoites can enter the AC; however, the aqueous humor (AH) contains factors that either induce encystment or kill the amoebae. METHODS: Descemet's membrane was isolated from pig corneas and was used to determine whether Acanthamoeba trophozoites could penetrate this membrane in vitro. In addition, the capacity of trophozoites to survive in AH was determined in vitro. Trophozoites (10(6)) were injected into the AC of hamster eyes, and the number of amoebae in the AC was determined by histopathology 1 to 15 days later. RESULTS: The amoebae penetrated Descemet's membrane within 24 hours of in vitro culture. Penetration was prevented by addition of serine protease inhibitors or a chicken monoclonal antibody against the Acanthamoeba serine protease MIP-133. Although AH induced encystment of the amoebae, cysts remained viable. Injection of amoebae into the AC induced a robust neutrophil infiltrate, which was associated with complete clearance by day 15 after AC injection. CONCLUSIONS: The findings suggest that A. castellanii is capable of penetrating Descemet's membrane and entering the AC. However, a robust neutrophil response is associated with the disappearance of intraocular trophozoites and suggests that cells of the innate immune apparatus are important in preventing Acanthamoeba keratitis from progressing to become an intraocular infection.