EyeWorld Asia-Pacific June 2013 Issue

53 EWAP CORNEA June 2013 Views from Asia-Pacific Jodhbir S. MEHTA, FRCS(Ed), FRCOphth(UKO) Head & Senior Consultant, Corneal & External Eye Disease Service Singapore National Eye Centre Adjunct Associate Professor, Duke-NUS Graduate Medical School of Singapore Tel. no. +65-62277255 jodhbir.s.mehta@snec.com.sg T he use of human amniotic membrane (HAM) in ophthalmology has increased over the last two decades. Currently, we use amniotic membrane in both its cryopreserved form and its dehydrated form. However, it is important to note that there are differences in composition between the different forms of HAM available. In 2010, our group published a paper comparing the ultrastructural properties of freeze-dried gamma irradiated HAM compared with cryopreserved HAM (published in Arch Ophthalmol. ). We showed that with the dehydrated forms there was loss of collagen IV, VII, laminin and fibronectin, and several growth factors. These may affect the use of this form of HAM in ocular surface reconstruction. The cryopreserved form is still our most commonly used form mainly due to the above findings. We find it useful as a carrier for stem cell reconstruction of the ocular surface whether this be ex vivo expansion of limbal cells, conjunctiva or oral mucosa. We also use HAM to seal small stromal perforations especially in cases of inflammatory eye disease. One of the issues of cryopreserved HAM is that the quantity of stroma varies depending on where the HAM is harvested. This can affect the thickness and hence the refractive index and transparency. We found that the thickest tissue (closest to the placenta) had the highest refractive index ( Brit J Ophthalmol. 2010). Hence, not all tissue is suitable for surface reconstruction across the visual axis. HAM is a useful biological substrate to aid in ocular surface reconstruction. However, the limitations and advantages of the different forms must be taken into consideration when using it for ophthalmic surgery. Editors’ note: Dr. Mehta declared no financial interests related to his comments. Dr. Akpek added the cryopreserved membrane “is more whitish and a bit thicker than AmbioDry2 (which is about 35 µm), so the next day vision isn’t as great. AmbioDry2 is a bit better on postop day one because the patient has some type of vision,” she said. “Most people have the impression that cryopreserved membrane speeds up the healing process better than the dry form, but that has not been my impression. But I use them in different kinds of cases, so I’m not able to compare them,” she said. Dr. Sippel agreed the indications for the different types of membranes are not the same. For one, because the ProKera is essentially a ring with a sheet of membrane across it, “it’s applied like a contact lens. It’s very easy to apply and can be done in the office without any need for glue or sutures,” she said. With the new reimbursement codes, “it allows us, from a practical standpoint, to go ahead and use amniotic membrane in the office.” EWAP Editors’ note: Dr. Tseng has a proprietary interest in his comments. None of the other physicians have any financial interests related to this article. Contact information Akpek : 410-955-5494, esakpek@jhmi.edu Gregory : 720-848-2500, darren.gregory@ucdenver.edu Sippel : 646-962-3126, kcs2002@med.cornell.edu Tseng : 305-274-1299, stseng@ocularsurface.com LASIK Surgery MORIA S.A. 15, rue Georges Besse 92160 Antony FRANCE Phone: +33 (0) 1 46 74 46 74 - Fax: +33 (0) 1 46 74 46 70 moria@moria-int.com - www.moria-surgical.com • Thin, 100-micron, planar flaps • Accuracy and predictability equivalent to Femto-SBK • Smoother stromal bed • No femto-complications • … At a fraction of the cost Think Thin SBK without femto-furrow James Lewis, MD (Elkins Park, PA, USA) 1. Lewis JS. Unanticipated stromal tissue loss following femtosecond flap creation. 28 th annual meeting of the ESCRS; Sept 4-8 2010; Paris, France. 2. Lewis JS. Skepticism about LASIK flap dogma. Ophthalmology Management . 2010; 14(9):40-45. Dr. Lewis has no financial interest and is not a paid consultant for Moria. IntraLase ® is a product and registered trademark of Abbott Medical Optics, Inc (Irvine, CA, USA). « We wanted to see the geometry, the anatomy of the flap edge. […] I was expecting the FS angle to be well defined, as these arguments have been made that it’s so much better and so much more stable. In actuality, I found discontinuity, a total absence of stroma and possibly stromal tissue loss. A week later you don’t see the gap in the OCT. What you see is an epithelial plug filling the furrow with a slightly different tissue density. We do not see the well-defined edges that are theorized to make enhancement safer and epithelial ingrowth a thing of the past. In fact, what we see may be the first sign that the femtosecond laser is not a panacea. […] Nothing suggestive of tissue loss was found in the Moria SBK cases. » 2 OCT pictures immediately after SBK flap creation 1 : Left: IntraLase ® 150kHz // Right: Moria SBK