Central corneal haze increased by radial keratotomy following photorefractive keratectomy.

PURPOSE: To report a case of central corneal haze induced by minimally invasive radial keratotomy (mini-RK) after photorefractive keratectomy (PRK) and subsequent deep lamellar keratoplasty. METHODS: We report a case (one eye of one patient) of central corneal haze that worsened after mini-RK was performed 2 years following PRK. Four years later, a second PRK was done, myopic regression was subsequently observed, and corneal haze persisted. Deep lamellar keratoplasty was performed and a corneal graft was taken, which was examined by light and electron microscopy. RESULTS: In the ablated area, irregularity of the basal membrane and hypertrophy of the corneal epithelium were observed. In the stromal layer, collagen fibers showed disorder in their disposition. Aggregated activated keratocytes were observed. An epithelial plug filling the gap of the RK incision persisted for 6 years after the mini-RK. The RK incision was easily divided when deep lamellar keratoplasty was performed and the patient obtained a stable visual outcome. CONCLUSIONS: It is possible that mini-RK enhancement after PRK induces central corneal haze and reduces corneal integrity. Deep lamellar keratoplasty for refractory corneal haze after refractive surgery was useful in this eye.

Separation of corneal stroma and Descemet's membrane during deep lamellar keratoplasty.

PURPOSE: To study the interface of the corneal stroma and Descemet's membrane and to report the histologic findings of the deep corneal stromal tissue removed during deep lamellar keratoplasty (DLKP). METHODS: The deep stromal tissues of four corneas were removed during DLKP and were examined histologically by light microscopy (LM) and transmission electron microscopy (TEM). RESULTS: Descemet's membrane appeared as a smooth surface under the surgical microscope during the removal of deep corneal stroma. Two of the four excised tissues showed a thin layer attachment to the deep stromal tissue by LM and TEM. The layer measured approximately 3.0 to 4.0 microm and was observed as a striated structure attached to the stromal tissue of both specimens. The other two specimens contained only stromal tissue. CONCLUSIONS: Separation of the deep stromal tissue from Descemet's membrane may occur within the Descemet's membrane, and the separation is probably between the anterior banded and the posterior nonbanded layer of Descemet's membrane in some cases during DLKP. The lamellar structure of the delaminated region suggests a mechanically weak segment of Descemet's membrane. The smooth surface of Descemet's membrane observed under a surgical microscope is not the actual interface of corneal stroma and Descemet's membrane.