Transplantation Blues: Inadvertent Staining of Amyloid Deposits With Trypan Blue.

PURPOSE: To describe inadvertent persistent staining of stromal amyloid deposits by trypan blue (TB) after penetrating keratoplasty (PK) and Descemet membrane endothelial keratoplasty (DMEK) performed in patients with corneal amyloidosis. METHODS: Case series of patients with corneal amyloidosis in whom intraoperative TB was used. RESULTS: One patient, hospitalized for acute rejection 6 weeks after DMEK, presented with an intense blue staining of small, spindle-shaped structures in the anterior half of the cornea. DMEK had been performed for endothelial failure of a previous PK procedure done 13 years earlier for advanced lattice corneal dystrophy (LCD). After 6 months, the stromal blue tattoo persisted with impaired visual acuity, and PK was performed. Blue-stained structures were amyloid deposits characteristic of LCD recurrence. In parallel, among 85 consecutive triple procedures (PK + cataract + intraocular lens [IOL]) performed over 7 years, in which TB was used, only patients with LCD (n = 18 eyes in 17 patients) or presumed secondary amyloidosis due to chronic inflammation (n = 1), presented an isolated intense blue ring of the graft-host interface. This persisted up to 7 years with no clinical consequence. CONCLUSIONS: TB can stain corneal amyloid deposits. After PK, staining is limited to the recipient peripheral cornea and has no apparent clinical consequence. However, during DMEK performed after a failed PK, TB stains fibrils accumulated during slow LCD recurrence and scattered on the whole graft. The long-term staining duration indicates strong interactions between TB and amyloid.

Micro-instillation of fluorescein with an inoculation loop for ocular surface staining in dry eye syndrome.

PURPOSE: To describe and validate the micro-instillation of fluorescein on the ocular surface by a disposable calibrated inoculation loop to improve corneal and conjunctival staining quality. METHODS: Accuracy and precision of the volume of 0.5% sodium fluorescein collected by a single use 1 µl-calibrated inoculation loop were measured using a precision balance. Twenty patients (40 eyes) suffering from dry eye syndrome were enrolled in a prospective interventional nonrandomized study. Fluorescein was instilled with the loop, and slit-lamp images were taken within 30 seconds using cobalt blue light with and without a yellow barrier filter. For comparison, after a washout period, the same images were retaken after instillation of one drop of fluorescein from a single-dose unit. The main outcome measure was the staining quality assessed by three experts, blind to the instillation method. Patient discomfort (tolerance, by a questionnaire) was also compared. RESULTS: The mean volume collected by the loop was 1.18 ± 0.12 µl, compared with 33.70 ± 6.10 µl using the single-dose unit. The loop avoided excess dye responsible for unpleasant tearing, masking of lesions and rapid diffusion into the stroma. Micro-instillation greatly improved image quality without losing information. The yellow filter further improved image contrast. Tolerance was excellent. CONCLUSION: The 1 µl-calibrated inoculation loop is a safe, convenient, inexpensive, disposable, sterile, well-tolerated tool for reproducible micro-instillation of commercial fluorescein. By greatly improving staining quality, it will help standardize assessment of dry eye severity.