Winter Congress of the European Society of Cataract and Refractive Surgeons 2021

In February of this year, the Winter Congress of the European Society of Cataract and Refractive Surgeons ¹ (ESCRS 2021) was held. Due to the situation with the global pandemic, the organizers had to conduct lectures in non-standard conditions, namely virtually. Let's briefly review the results of the most interesting scientific studies.

Studies have shown that superficial ablation methods such as PRK (with and without alcohol), LASEK, Epi-LASIK and transepithelial PRK show equally good results. These surgeries were evaluated separately in cases of young patients, small visual abnormalities (errors) in the thin cornea, epithelial membrane dystrophy, corneal irregularities (cases of individual ablation), or dry eye symptoms. In all cases, it is still recommended to use Mitomycin-C immediately after laser ablation to avoid corneal opacity (haze).

The effectiveness of individual laser vision correction from different manufacturers available on the market was also considered, whereas each technology is special in its own way. It is still debated whether sequential crosslinking (CXL) with PRK or concurrent crosslinking should be chosen to treat keratoconus and achieve better results.

One of the reports also mentioned the imminent appearance of a new mobile laser from Carl Zeiss Meditec AG to compensate for hyperopia. As is known from past congresses like ESCRS 2019, research has been conducted since 2015. The current VisuMax^® system offers a lenticular extraction operation to correct myopia (nearsightedness). Also two concepts from the same manufacturer were presented: Small Lenticule Addition Keratoplasty (SLAK) and Presbyopia Allogenic Refractive Lenticule (PEARL). In the first case, it is an additional keratoplasty with a small lenticule, i.e. keratoplasty with the addition of a small lenticule or, more simply, transplantation of a donor lenticule for the treatment of hyperopia or keratoconus. In the second case, it is a refractive lenticular transplant for the treatment of presbyopia.

Studies from the Russian Federation have shown a successful use of lenticule extraction by the ReLEx SMILE^® method with a VisuMax^® laser to correct myopia and astigmatism, that was as a result after a radial and tangential keratotomy (the notorious incision operations performed in the nineties).

Results in the field of transplantology were presented, namely, it was shown that transplantation of limbal (the junction of the cornea with the sclera) stem cells (LSC) is necessary before transplantation of the cornea, leading to opacity, vascularization, etc. LSC transplantation is strongly recommended before corneal transplantation. On the other hand, stem cells require expensive laboratory equipment, so this method is not always possible.

Anterior Camellar (lamellar) Keratoplasty (ALK) has been shown to have several advantages over Penetrating Keratoplasty (PK). It should be understood that in the case of ALK, only a part of the cornea is transplanted, i.e. the depth of the affected tissue varies in the range of 80-250 µm. The advantages of ALK over PK include a decrease in the risk of graft rejection and loss of its endothelial cells, as well as a decrease of the risk of complications associated with intraocular surgery such as cataract formation and secondary glaucoma. Benefits also include shorter post-operative steroid use and more durable healing.

After the operation to remove the pterygium, i.e. germination of the mucous membrane of the eye, glue can be successfully used instead of sutures to secure the conjunctiva. Moreover, conjunctival flaps can be used to repair corneal damage when other treatment options have failed. You can also use amniotic membranes (one of the thickest membranes in the human body) as patches for conjunctival defects or severe corneal burns.

Of particular interest were the results of pig tissue transplantation. The lenticules (corneal layers) of the pig underwent a decellularization process (removal of the cellular component) and had a diameter of about 7 mm and a thickness of 100–120 µm. A femtosecond laser was used to create a pocket in the cornea. This tissue was then implanted internally, followed by a corneal crosslinking procedure 3 months later in most eyes. Thus, it was shown that decellularized porcine lenticules and the subsequent crosslinking procedure lead to an improvement in visual acuity. Control observation after 18 months confirmed the transparency of the cornea and the immunological stability of the implants.

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  Bibliography

1. European Society of Cataract & Refractive Surgeons. ESCRS 2021 Winter. ESCRS Winter Meet Virtual 2021. https://www.escrs.org/winter-virtual-meeting2021.