Freeze-Dried, Cryopreserved Membranes Equally Effective for Corneal Ulcers

Corneal ulcer
MODEL RELEASED. Corneal ulcer. Close-up of the right eye of a 72-year-old man with a dendritic corneal ulcer (cloudy area). The cornea is the transparent front part of the eye. A corneal ulcer (ulcerative keratitis) is a form of inflammation of the cornea. It is usually due to some form of infection.
Limited access to cryopreserved amniotic membranes brought about by the pandemic was effectively remedied by replacement with chorion-free, freeze-dried membranes, according to a report.

Chorion-free, freeze-dried amniotic membranes (FD-AM) are likely an effective substitute for cryopreserved amniotic membranes (C-AM) in the treatment of corneal ulcers, according to a study published in Cornea. 

Researchers included 50 participants who received either FD-AM (n=28) or C-AM procedures (n=22) in the study. They obtained demographic data for all patients and compared a variety of baseline characteristics between the groups. Postoperative follow up occurred at intervals of 72 hours, 1 month, and 3 months. 

The investigators observed similar demographics between the 2 groups. They categorized disease etiologies as bacterial, herpes, acanthamoeba, fungal, neurotrophic keratitis, chemical corneal burn, or other, and sought associations between the groups (25%, 33%, P =.56; 11%, 14% P =.75; 7%, 5%, P =.70; 0%, 5%, P =.25; 11%, 14%, P =75; 11%, 5%, P =.43; 36%, 27%, P =.53, for the FD-AM and C-AM groups, respectively).  Age and etiology revealed no association with ulceration size (P =.15 and P =.38, respectively), and corneal ulcer depth was similar between the 2 groups (64% and 77%, respectively, P =.32). The difference in follow up time was the only statistically significant factor between the groups (18.2±9.5 months C-AM, 3.0±1.4 months F-AM; P <.01).

Likewise, complications including infection, descemetocele, and perforation were uncommon and comparable between the groups (0%, 0%; 4%, 5%; 7%, 5%,  FD-AM and C-AM groups, respectively).

“Corneal healing was not different between FD-AM and C-AM [when] used as an overlay patch, regardless of the depth of the ulcer,” according to the investigators. Regardless of the treatment method used “at 1 month, we were not able to show any difference for corneal healing in both deep stromal ulcers and anterior stromal ones.”

Study limits include a single center design, retrospective nature, small sample size, and possible confounding due to the use of soft bandage lenses. 


Memmi B, Leveziel L, Knoeri J, et al. Freeze-dried versus cryopreserved amniotic membranes in corneal ulcers treated by overlay transplantation: a case control study. Cornea. 2022; 41(3): 280-285. doi:10.1097/ICO.0000000000002794