Evidence-Based Endothelial Rehabilitation

Pediatric endothelial keratoplasty: a systematic review and individual participant data meta-analysis

BACKGROUND

Recently, endothelial keratoplasty (EK) has been increasingly considered the first intervention in pediatrics with isolated corneal endothelial dysfunction. This systematic review aims to investigate the current evidence about the advantages, disadvantages, technical challenges, and clinical outcomes of EK in the pediatric group.

METHOD

All the English literature relevant to pediatric EK was searched in PubMed, Embase, Scopus, and Cochrane databases with appropriate keywords. Relevant data were pooled to conduct an individual participant data meta-analysis.

RESULTS

Of 1646 articles found initially, 35 articles were finally eligible to be included in our study. A total of 154 eyes of 107 patients underwent Descemet's stripping automated endothelial keratoplasty (DSAEK). Congenital hereditary endothelial dystrophy (CHED) was the most reported indication for pediatric DSAEK (108 eyes). Descemet's membrane endothelial keratoplasty (DMEK) was performed in 2 eyes of 2 cases, one with PPCD and another one in a patient with Kearns-Sayre syndrome. Owing to some specific anatomical and physiological pediatric characteristics, some modifications in a standard procedure were suggested. The average follow-up period was 23.80 ± 20.18 months (3 months to 8.5 years). Seventy-six eyes who had a mean best-corrected visual acuity (BCVA) of 1.36 ± 0.70 (0.49 to 3) logMAR preoperatively found mean BCVA of 0.51 ± 0.33 (0.04 to 2) logMAR postoperatively. Graft dislocation was the most reported complication (26 eyes). The rate of other complications was low. Endothelial cell loss was reported from 8.3 to 63.7% after pediatric EK with follow-up duration from 3 months to 8.3 years.

CONCLUSION

EK procedures, despite some technical challenges, are feasible surgical techniques with acceptable visual and anatomical outcomes in the management of pediatrics with corneal endothelial dysfunction and minimal stromal involvement.

Comparative analysis of biomechanical parameters of the corneas following Descemet membrane endothelial keratoplasty and contralateral healthy corneas

PURPOSE

To compare the biomechanical properties of the unilateral operated corneas in patients who had undergone Descemet membrane endothelial keratoplasty (DMEK) for pseudophakic bullous keratopathy (PBK) with those of the contralateral normal corneas.

METHODS

This was a retrospective cohort study conducted at university hospitals (Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel, and S. Fyodorov Eye Microsurgery State Institution, Moscow, Russia). Forty eyes of 20 patients who underwent DMEK for unilateral PBK 3.5 to 36 months ago and with normal fellow eyes were included in the study. An ocular response analyzer was used to measure the corneal biomechanical properties in the operated and normal fellow eyes. The main outcome measures were corneal hysteresis (CH) and corneal resistance factor (CRF).

RESULTS

The mean CH (8.4 ± 1.5 mmHg vs. 8.2 ± 1.5 mmHg, P = 0.707) and the mean CRF (8.7 ± 1.6 mmHg vs. 8.3 ± 1.6 mmHg, P = 0.419) values did not show any statistically significant difference between the operated and the normal fellow eyes.

CONCLUSIONS

In our study, the corneas that underwent DMEK for PBK showed normal values for biomechanical parameters. These findings support the previous studies that have reported near complete visual, functional, and ultra-structural rehabilitation of the corneas following DMEK.

Different graft thicknesses after Descemet stripping endothelial keratoplasty for bullous keratopathy in the two eyes of the same patient

Objective

To describe a very unique case of two Descemet stripping automated endothelial keratoplasty (DSAEK) surgeries performed in both eyes of the same patient with an extremely different graft thickness and overall corneal thickness but with the same corrected distance visual acuity (CDVA) 2 years after surgery.

Case presentation

A 75-year-old woman with bilateral bullous keratopathy (BK) was submitted to DSAEK surgeries in both eyes, first in right and after 6 months in left eye. CDVA was 20/160 in the right eye and 20/63 in the left eye. Corneal thickness evaluated by anterior segment optical coherence tomography was 569 µm in the right eye and 560 µm in the left eye. The root mean square (RMS) was 2.1 in the right and left eyes. Endothelial cell densities were not detectable in both eyes. The estimated precut donor graft thickness from eye bank was 250 and 40 µm in the right and in the left graft, respectively. Two years after surgery CDVA was 20/25 in both eyes. Corneal thickness was 633 µm with a lenticule thickness of 206 µm in the right eye and 439 µm with a lenticule thickness of 48 µm in the left eye. The RMS was 1.7 in the right eye and 1.4 in the left eye. Endothelial cell density was 2.272 cells/mm² in the right and 2.154 cells/mm² in the left eye.

Conclusion

DSAEK was safe and effective in the treatment of BK. In our report, the visual outcome resulted to be poorly related either to donor graft thickness or to postoperative corneal thickness.

[Corneal endothelial cell therapy, a review]

In France, endothelial dysfunction represents approximately one half of the indications for corneal transplants performed each year. However, the use of endothelial keratoplasty is limited by the technical difficulty of the procedure, a shortage of available grafts, and the potential for graft failure or rejection. These limitations are driving researchers to develop new, less invasive, and more effective therapies. Corneal endothelial cell therapy is being explored as a potential therapeutic measure, to avoid the uncertainty associated with grafting. The human cornea is an ideal tissue for cell therapy. Due to its avascular and immunologically privileged characteristics, transplanted cells are better tolerated compared with other vascularized tissues and organs. Advances in the field of stem cell engineering, particularly the development of corneal epithelial stem cell therapy for the treatment of severe ocular surface disease, have aroused a massive interest in adapting cell therapy techniques to corneal endothelial cells. This chapter, based on a review of the literature, aims at educating the reader on the latest research in the field of corneal endothelial cell therapy.

A review of the evidence for in vivo corneal endothelial regeneration

Human corneal endothelium has long been thought to be a nonmitotic cell layer with no endogenous reparative potential. Pathologies that damage endothelial function result in corneal decompensation and, if untreated, blindness. The mainstay of treatment involves partial or complete corneal replacement, amounting to 40% of all corneal transplants performed worldwide. We summarize the case reports describing complications postoperatively in the form of (sub)total graft detachment and those resulting in postoperative bare stroma. Complications during cataract and glaucoma surgeries leading to an uncovered posterior cornea are also included. We discuss the newer treatment strategies that are alternatives for current Descemet membrane endothelial keratoplasty and Descemet stripping automated endothelial keratoplasty, including partial grafts and stripping of the diseased cell layer. In more than half of the cases reviewed, corneal transparency returned despite incomplete or no corneal endothelial cell transplantation. We question the existing paradigm concerning corneal endothelial wound healing in vivo. The data support further clinical study to determine the safety of simple descemethorexis in central endothelial pathologies, such as Fuchs endothelial corneal dystrophy, where presence of healthy peripheral cells may allow successful corneal recompensation without the need for donor cells.