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Advances in regenerative medicine may alter treatment of corneal endothelial diseases
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The last decade has seen significant advances in the field of corneal surgery. Various lamellar keratoplasty techniques have been refined, and endothelial keratoplasty in the form of Descemet’s stripping automated endothelial keratoplasty has now become the standard for endothelial diseases. Worldwide, DSAEK is now one of the most common techniques for endothelial transplant, with excellent functional outcomes.
However, Descemet’s membrane endothelial keratoplasty, with its better functional results and faster visual recovery, is now challenging DSAEK. The concern with DMEK is the handling of the delicate Descemet’s membrane and endothelium and the surgical trauma to the endothelium that occurs during the insertion of the scrolled tissue into the anterior chamber. The technique to unscroll the Descemet’s membrane endothelial complex, the prolonged time to unfold, as well as issues with identifying the correct orientation are challenges facing the novice surgeon. Various techniques to assist the insertion and reduce the surgical time and trauma to the endothelium, such as Busin’s technique of tri-folding the donor endothelium complex on a scaffold of soft contact lens to transfer the tissue using a bimanual injector system or that by Tan using a Descemet’s mat or corneal tissues along with the endo inserter, are interesting concepts.
Simultaneously, the last few years have also focused on stimulating the migration of healthy peripheral corneal endothelial cells to the center to achieve corneal clarity.
Selectively stripping the central cornea with significant guttae (descemetorhexis) alone without tissue transplant seems to work in some cases, especially if the peripheral endothelial cell reserve is good. However, we still do not know which patients will benefit from a descemetorhexis alone. The size of the descemetorhexis is normally much smaller, around 4 mm to 6 mm, as compared with the routine size of 8 mm that we use for DSAEK/DMEK. Unlike the vision recovery in DMEK, vision recovery in descemetorhexis alone might take a longer time. The patient will need to use a bandage contact lens for a couple of weeks until the migrating endothelial cells close the central defect.
Kinoshita put forth another interesting concept of treating endothelial diseases by increasing the endothelial cell proliferation, especially in early stages of the disease process. This has been shown to be possible using topical application of ROCK inhibitor drops. In advanced endothelial dysfunction, the initial results of cultivating endothelial cells on a type 1 collagen matrix or lamellar cornea and transplanting it like a sheet in DSAEK or injecting a suspension of endothelial cells into the anterior chamber with addition of ROCK drops to promote endothelial cell multiplication and adhesion to the Descemet’s are interesting concepts that are already in clinical trial with impressive early results. In the initial patients, Kinoshita just scraped the endothelial cells without physically removing the Descemet’s membrane before injecting the cultivated cell suspension. They noticed corneal clarity in a couple of weeks, and the visual recovery in the first few patients has been comparable to DMEK. In subsequent trials the researchers might consider striping the Descemet’s membrane to see if it results in a faster visual recovery.
These advances in the field of regenerative medicine might soon help us treat corneal endothelial diseases using just topical drops or intracameral injections, deferring the need for extensive surgeries and prolonged recovery times with the added advantage of reduced risk of rejection.
References:
Busin M, et al. Ophthalmology. 2016;doi:10.1016/j.ophtha.2015.10.050.
Koizumi N, et al. Exp Eye Res. 2012;doi:10.1016/j.exer.2011.10.014.
Moloney G, et al. Can J Ophthalmol. 2015;doi:10.1016/j.jcjo.2014.10.014.
Rodríguez-Calvo-de-Mora M, et al. Ophthalmology. 2015;doi:10.1016/j.ophtha.2014.09.004.
For more information:
Dennis S.C. Lam, MD, FRCOphth, can be reached at State Key Laboratory in Ophthalmology, Sun Yat-Yen University, 54 South Xianlie Road, Guangzhou 510060, People’s Republic of China; email: dennislam.gm@gmail.com.
Disclosure: The authors report no relevant financial disclosures.