PMC3589195_01
Slit-lamp photographs of left eye following intrastromal corneal ring segments (Intacs ) insertion. (A) Four months after Intacs insertion. (B) Spontaneous extrusion of inferior Intacs ring implant (arrow) 5 months following original insertion and prior to ring replacement. (C) Initial stromal infiltrates observed 8 months post Intacs insertion (3 months post replacement). (D) Stromal infiltrates at 10 months after initial Intacs insertion and prior to therapeutic keratoplasty.
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Good visual rehabilitation was obtained following Intacs insertion (uncorrected visual acuity, OS 20/40; best-corrected visual acuity OS 20/25) and was uneventful at 4 months post insertion (Figure 1A). Spontaneous extrusion of the inferior intrastromal corneal ring segment with no indication of infection was noted 5 months after insertion (Figure 1B), at which time it was removed. Eight months post Intacs implantation (3 months post replacement), the location of the lower lateral edge of the intrastromal corneal ring segments showed an epithelial defect and infiltrate on slit-lamp examination (Figure 1C). The infiltrate progressed into the deep cornea at the level of the intrastromal corneal ring segments at approximately 60% thickness (Figure 1D).
Histopathologic analysis of keratectomy specimen.. Notes: Micrograph of corneal tissue demonstrating a perforating corneal ulcer (arrow) with Intacs  insertion channels (asterisks) and dense mid-stromal infiltrate (periodic acid-Schiff, original magnification 20x). Insert: micrograph of cultured Candida parapsilosis yeast with central nuclei and broad-neck buds (periodic acid- Schiff, original magnification 20x).
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The corneal tissue clearly demonstrated insertion channels for the previously removed intrastromal corneal ring segments and a perforating corneal ulcer (Figure 2). As seen in the Figure 2 insert, C. parapsilosis yeast forms have darker staining central nuclei and produce broad-neck buds.
Panfungal polymerase chain reaction analysis.. Notes: Paraffin-embedded corneal specimens and control DNA samples were evaluated using a panfungal polymerase chain reaction assay, electrophoretically resolved on a 1.8% agarose Tris-borate-EDTA gel, and visualized using ethidium bromide and ultraviolet excitation. DNA extracted from the current case report specimen (lane 1), DNA extracted from a confirmed Candida parapsilosis infectious crystalline keratopathy clinical specimen (lane 2), 1 x 104 genome equivalents of DNA extracted from cultured C. parapsilosis (lane 3), 1 x 104 genome equivalents of DNA extracted from cultured Candida albicans (lane 4), 1 x 104 genome equivalents of DNA extracted from cultured Candida guilliermondii (lane 5), 1 x 104 genome equivalents of DNA extracted from cultured Candida lipolytica (lane 6), 4 x 104 copies of plasmid pCA1 (lane 7), deionized distilled water as a negative control (lane 8), and a 50 bp size marker ladder (lane 9).
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The current keratoplasty specimen produced a PCR amplicon product of approximately 311 bp, as did the crystalline keratopathy corneal specimen and the DNA from cultured C. parapsilosis (Figure 3). The control DNA from cultured C. albicans, C. guilliermondii, and C. lipolytica produced amplicons of 338 bp, 379 bp, and 242 bp, respectively (Figure 3) in agreement with the predicted sizes (Table 1).