Abstract
Abstract: :
Purpose: Intracorneal ring segments (ICRS) are plastic inserts placed in the peripheral cornea to correct moderate myopia. Postoperatively, lamellar channel deposits have been observed with slit lamp exam, confocal microscopy, and optical coherence tomography. Explanted segments were evaluated by scanning electron microscopy (SEM) to better understand the nature of the deposits. Methods: ICRS from four patients (five eyes), who had undergone uneventful ICRS implantation, were explanted because of residual refractory error. Table 1 presents patient information. Table 1 All eyes were quiet in the period from post-implantation to explantation. All corneas returned to pre-op curvature after explantation with no signs of inflammation. Following explantation, the segments were fixed in 3% cacodylate buffered glutaraldehyde and prepared by standard SEM technique. Each segment was divided into halves and mounted on opposite sides of an aluminum stub in order to image the anterior and posterior side of each segment. Results: SEM of the ICRS surfaces revealed a focal film, which was relatively amorphous with small focal sites of crystalline structures seen in all of the cases. In addition, Patient #1 had structures that could represent cell cytoplasm. In Patient #3, there was a single site observed that appeared to have a cluster of round, ball-like structures coated with the film. In Patient #4, there was a small granular and fibrillar material that overlaid the film. Conclusion: These findings could be consistent with degradation products of stromal cells. These findings differ from studies by confocal microscopy in the past, which suggested the deposits to be composed of sheets of epithelial cells (Kim FF, ARVO Abstract #4875, 2000). Tissue cultures, TEM, and biochemistry studies may help to further characterize these deposits. Supported in part by Addition Technology Inc., NEI#5P30EYO1867, & Research to Prevent Blindness.
Keywords: cornea: clinical science • microscopy: electron microscopy