Light and Transmission Electronic Microscopy Evaluation of Lyophilized Corneas

Farias, Roberta; Sousa, L.B.; Filho, Acácio Alves Souza Lima; Lourenço, Andréa C S; Tanakai, Márcia H; Freymüller, Edna

doi:10.1097/ico.0b013e31816ed54c

Cited by 10 publications

(3 citation statements)

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“…Degeneration of keratocytes with necrotic and apoptotic changes due to the dehydration process is expected. It has been observed with ultrastructural evaluation in dehydrated corneas after lyophilization or cryopreservation, with or without the use of a cryoprotective agent (10,23). For this reason, it was not necessary to include a control group to compare air-drying with other procedures for dehydrating corneal tissue.…”

Section: Discussionmentioning

confidence: 99%

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Ultrastructural Analysis of Rehydrated Human Donor Corneas After Air-Drying and Dissection by Femtosecond Laser

et al. 2021

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Purpose: To evaluate the efficiency of femtosecond laser (FSL) incision of rehydrated human donor corneas after air-drying and its effects on corneal structure.Methods: We compared the rehydrated and fresh-preserved corneas by microscopy following Victus-Tecnolas FSL treatment for straight-edge anterior lamellar keratoplasty (ALK). The corneas were dehydrated at room temperature under a laminar-flow hood.Results: To obtain the horizontal cut in rehydrated corneas, we increased the FSL pulse energy to 1.2 μJ from 0.80 μJ applied for the fresh corneas and obtained a clear-cut separation of the lamellar lenticule cap from the corneal bed. Light microscopy showed regular arrangement of stromal collagen lamellae, with spaces in between the fibers in the corneal stroma in the fresh and the rehydrated corneas, but the uppermost epithelial layers in the rehydrated corneas were lost. Transmission electron microscopy (TEM) revealed no signs of thermal or mechanical damage to the corneal structure. The epithelial basal membrane and Bowman's layer maintained their integrity. The epithelial basal layer and cells were separated by large spaces due to junction alteration in the rehydrated corneas. There were gaps between the lamellar layers in the stroma, especially in the rehydrated corneas. Keratocytes displayed normal structure in the fresh corneas but were devoid of microorganules in the rehydrated corneas. Minor irregularities were observed in the vertical incision and the horizontal stroma appeared smooth on scanning electron microscopy.Conclusion: The corneal stroma of rehydrated corneas maintained morphology and integrity, while corneal cellular components were generally altered. When corneas are intended for FSL-assisted ALK, effective stromal bed incision is best achieved at a laser power higher than that currently adopted for fresh corneas.

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Section: Discussionmentioning

confidence: 99%

“…The conventional preservation times of whole corneas and stromal lenticules can be lengthened by cryopreservation/vitrification (5), dehydration without freezing (6), glycerolization (7)(8)(9), lyophilization (or freeze-drying) (10)(11)(12), and sterilization by gamma irradiation (13).…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural Analysis of Rehydrated Human Donor Corneas After Air-Drying and Dissection by Femtosecond Laser

et al. 2021

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“…Lyophilization is thought to optimize preservation of corneal architecture. Recent studies using light and transmission electron microscopy found that lyophilization preserved general corneal structure, parallelism of the collagen fibers, Bowman's layer and the epithelial basement membrane 1718. No comparative studies have yet determined if lyophilized and glycerol-dehydrated tissues exhibit ultrastructural differences following tissue rehydration and, if detected, to what extent these differences affect tissue quality and corneal transparency.…”

Section: Introductionmentioning

confidence: 99%