Endothelial Keratoplasty: Yesterday and Today (literature review)

The article presents the literature review on the history and development of endothelial keratoplasty, which is one of the options for corneal transplantation. It includes different surgical techniques (posterior lamellar keratoplasty, with removal of the a circular section of the Descemet's membrane, deep lamellar endothelial keratoplasty, posterior lamellar keratoplasty (automated), etc.) used for the treatment of patients with pathology of the corneal endothelium and is characterized by replacement of it with corneal back layers of the donor graft. Ophthalmic surgical practice has convincingly shown a significant advantage of modern methods of endothelial keratoplasty in comparison with classical penetrating keratoplasty, which is a long-term standard in the treatment of corneal pathology. Key word: endothelial keratoplasty, the pathology of the corneal endothelium, corneal transplantation, posterior lamellar keratoplasty, deep lamellar endothelial keratoplasty.

Experimental Rationale for Using an Eximer Laser for Preparation of Ultrathin Graft for Posterior Lamellar Keratoplasty

Purpose. To rationale experimentally the use of an excimer laser for forming an ultrathin transplant for posterior lamellar keratoplasty. Materials and methods. Atomic force microscopy was used for examination of 10 samples. Control group was 5 corneal flaps obtained by mechanical microkeratome (Moria SLK-2, France). Main group — 5 corneal flaps, obtained by microkeratome and underwent photoablation by “Microscan 500” (Optosystems, Troick, RF) excimer laser at 50 um depth. For quantification of endothelial loss 10 donor corneas (5 pairs) with viable endothelium, preserved in Borzenok—Moroz media, were used. Two groups were formed: main — 5 ultrathin transplants obtained by consistent application of microkeratome and excimer laser, control (from the paired eyes of same donors) — ultrathin transplants prepared by two cuts of microkeratome. Detection of live and dead endothelial cells (EC) was provided by Calcein Violet 450 and Propidium Iodide “vital” fluorescent dyes. Nonparametric Mann—Whitney test was used for statistical analysis. Coefficient of reliability (p < 0.05) was considered to be significant. Results. RMS (roughnessmean square) of the transplant, prepared by excimer laser was — 24.17 ± 12.4 um, and RMS of the transplant prepared by microkeratome — 22.3 ± 18.3 um. Statistical analysis did not reveal significant differences in RMS values in the mentioned groups (p > 0.05). EC death in excimer laser group was 10.35 ± 5.84 %. EC death in microkeratome group — 8.06 ± 1.31 %. No statistically reliable difference of EC death was revealed in the 2 groups (p > 0.05). Conclusions. The investigation has showed identical RMS values in the examined groups, representing high optical qualities of the transplant prepared by excimer laser. EC loss was also comparable in 2 groups. The received results indicate considerable potential of excimer laser transplants for posterior lamellar keratoplasty.

Еfficacy of Combined Treatment of Epithelial and Endothelial Corneal Dystrophy Using Corneal Crosslinking and Automated Posterior Lamellar Keratoplasty

The purpose: to establish a combined approach to the treatment of patients with epithelial and endothelial cornea dystrophy (EED) based on a comparative study of the results of one-step and two-step methods. Patients and methods. The study included 75 patients (81 eyes) with corneal EED, who underwent surgical treatment at the Ufa Eye Research Institute from 2011 to 2016. The patients were divided into two groups — the main group consisted of 43 (46 eyes, 57 %) patients, who underwent the first stage of the CC before surgical treatment of EED, the second stage after 1–12 months — automated posterior lamellar keratoplasty (APLK). In the control group, isolated APLK was performed in 32 (35 eyes, 43 %) patients. Results. After CC (1–10 days) in the main group an increase in corneal thickness due to edema enhancement in the cornea stroma was observed in patients with stage I–III of the corneal EED. After 3 months, a decrease in corneal thickness was recorded in patients of the main group with I-II stages of the disease (p < 0.05), after 6 months — in all stages of the corneal EED compared with the control group (p < 0.05). According to optical coherence tomography (OCT), a decrease in the total cornea thickness in both зфешутеы groups was noted within 12 months after APLK: in the main group from 667 ± 65 μm initially to 594 ± 31 μm, in the control group, where there was a pronounced corneal edema from 787 ± 56 to 612 ± 67 μm. Conclusion. Corneal cross-linking in patients with I–III stages of corneal EED provides improvement of the cornea, manifested in reducing edema and its thickness. It allows to delay the implementation of the automated posterior lamellar keratoplasty without corneal deterioration in patients with stage I up to 6–12 months, in patients with stage II–III up to 3–6 months.