Cryopreserved amniotic membrane enhances CXL recovery
Click Here to Manage Email Alerts
Corneal collagen cross-linking is a widely adopted therapy for pathologies in which strength of the cornea is compromised.
It is best known for treating keratoconus, a disease that causes corneal thinning and distortion that can lead to vision loss, if untreated. CXL works by infusing and saturating the corneal stroma with riboflavin and using ultraviolet light to initiate a cross-linking reaction within the cornea. The process strengthens and stiffens the cornea and can slow or halt the progression of keratoconus.
Postop complications
When facing a complication after CXL, it is critical to prevent further damage and to quickly heal the ocular surface. Since the FDA approved CXL for treating keratoconus, we have been successfully using cryopreserved amniotic membrane (CAM) (Prokera, Bio-Tissue) postoperatively for select CXL cases. The objective for treating with Prokera is to prevent non-healing epithelial defects after CXL and avoid potential complications including infections, scarring and corneal haze.
CAM retains heavy-chain hyaluronic acid/pentraxin 3 (HC-HA/PTX3), the biologic matrix that has been identified as being responsible for amniotic membrane’s (AM) anti-inflammatory and regenerative healing properties. HC-HA/PTX3 helps reduce scar formation, which untreated can lead to impaired vision. Dehydrated AM tissue does not retain this critical biologic compound. Also, research suggests that in addition to stimulating active healing, CAM promotes corneal nerve regeneration. Normal corneal innervation is important to maintain a healthy corneal surface.
Chain reaction
Another reason we use CAM for these difficult CXL cases is that Prokera encircles the AM with a fixed ring. That stabilizing ring, which rests on the conjunctiva, helps to maintain the membrane’s placement over the corneal surface and augments the healing process. Dehydrated AM requires the additional use of a bandage contact lens (BCL) to help maintain placement. In the case of extra steep keratoconic corneas, if the BCL moves too much or comes off, it is highly likely that it will take the dehydrated AM with it.
Some of our patients with CXL have a reduction in their steepest keratometry readings of 2.5 D. It is not uncommon to see these patients achieve two to three lines of improvement in their visual acuity at 3 months postop. With the combination of CXL and CAM, we stabilize the corneal surface and even maintain a therapeutic reservoir for our postoperative medications. We leave the CAM in place for 3 to 5 days. In most cases, the cornea is healed after 3 days; however, there are instances in which healing takes longer, and in those cases, a second CAM can be applied.
When we use CAM instead of a BCL after CXL, we are able to use less steroid because of Prokera’s anti-inflammatory effects. In many cases, less steroid means quicker healing. Furthermore, we get more uniform antibiotic coverage using the Prokera ring because it acts like a depot for the antibiotic, as well as the steroid. There is comfort in knowing that the patient is still getting antibiotic delivered to their eye hours after it is applied.
Better postop protocol
A postoperative BCL and steroid/antibiotic combination is sufficient for some cases of CXL, but in many instances, the keratoconic anatomy prevents a BCL from fitting properly, providing an area ripe for irritation, poor central healing and postop haze/scarring. Including CAM in the postoperative protocol obviates problems associated with ill-fitting BCLs and helps avoid complications from non-healing epithelial defects, including infections and haze/scarring, which is crucial to long-term CXL visual outcomes.
- References:
- Cooke M, et al. J Wound Care. 2014;doi:10.12968/jowc.2014.23.10.465.
- Jirsova K, et al. Cell Tissue Bank. 2017;doi:10.1007/s10561-017-9618-5.
- John T, et al. J Ophthalmol. 2017;doi:10.1155/2017/6404918.
- Rock T, et al. Ann Transplant. 2018;doi:10.12659/AOT.906856.
- Tsend SC. Invest Ophthalmol Vis Sci. 2016;doi:10.1167/iovs.15-17637.
- Watson CT, et al. Genes Immun, 2012;doi:10.1038/gene.2012.12.
- For more information:
- Jay K. Mattheis, MD, MSPH, FACS, can be reached at Wellish Vision Institute, 2110 E. Flamingo Road, Las Vegas, NV 89119; email: jkm711@mac.com.
Collapse
Read more about
Click Here to Manage Email Alerts