Assessment of endothelial cell density and corneal thickness in corneal grafts an average of 5 years after penetrating keratoplasty

Abstract

SummaryBackground Corneal transparency is a useful indicator for corneal function. Our aim was to investigate central corneal endothelial cells and corneal thickness in transplanted corneas at an average of 5.4 years after penetrating keratoplastyPatients and methods The study involved 68 perforated keratoplasty patients with at least a 1 year followup. Post-operatively, the central corneal endothelial layer was observed using a contact specular microscope. Central endothelial cell density, corneal thickness and the coefficient of variation of endothelial size were statistically analysed.Results The post-operative follow-up time was ranging from 12 months to 23 years. Endothelial cell density (ECD) was 1,501 ± 249 cell/mm 2 . The average cell size was 673.6 ± 98.3 μm 2 , and the coefficient of variation of cell size was 0.61 ± 0.11. No difference in ECD was detected between diagnostic groups. Corneal thickness was 0.56 ± 0.06 mm. Correlation between ECD and post-operative time was not significant (r = 0.02; p = 0.85).Conclusion Our study concluded that ECD showed a higher rate of decrease after penetrating keratoplasty with no relation to pre-operative diagnosis.Keywords Endothelial cell loss · graft survival · penetrating keratoplasty · specular microscope Bestimmung der Endothelzelldichte und der Hornhautdicke in Hornhauttransplantaten circa 5 Jahre nach einer penetrierenden Keratoplastik Zusammenfassung Hintergrund Die Transparenz der Cornea ist ein nütz-licher Indikator der Funktion der Hornhaut. Das Ziel unserer Studie war es, die zentralen Endothelzellen der Cornea sowie die Dicke der Hornhaut in transplantierten Hornhäuten circa 5,4 (im Durchschnitt) Jahre nach penetrierender Keratoplastik zu untersuchen.Patienten und Methoden In die Studie wurden 68 Patienten nach perforierter Keratoplastik aufgenommen, die zumindest 1 Jahr nachuntersucht worden waren. Postoperativ wurde die zentrale Endothelschicht der Hornhautmittel seines Kontakt-Spekular Mikroskops untersucht. Die Dichte der zentralen Endothelzellen, die Dicke der Hornhaut und der Variations-Koeffizient der Größe des Endothels wurden statistisch analysiert.Ergebnisse Der Zeitpunkt der postoperativen Kontrollen variierte von 12 Monaten bis 23 Jahren. Die Endothelzelldichte (EZD) lag bei 1501 ± 249 Zelle/mm 2 . Der Mittelwert der Zellgröße war 673,6 ± 98,3 μm 2 und der Variationskoeffizient 0,61 ± 0,11. Es gab keinen Unterschied in der EZD zwischen den nach Diagnosen eingeteilten Gruppen. Die Korrelation zwischen der EZD und dem Zeitabstand zur Operation war nicht kant (r = 0,02; p = 0,85).Schlussfolgerung Unsere Studie zeigt unabhängig von der präoperativen Diagnose eine abfallende Tendenz der EZD nach penetrierender Keratoplastik.

Efficacy and Safety of Deep Anterior Lamellar Keratoplasty vs. Penetrating Keratoplasty for Keratoconus: A Meta-Analysis

“…Although the mean ECC in PKP group was reduced more than that in DALK group, but we found there was no statistically significant difference between the mean CCT of the two groups. The similar results were reported by Kettesy B [ 55 ], who found that there was no correlation between ECC and corneal thickness. Kus MM [ 56 ] proved that even if ECC decreased significantly, as long as an acceptable density was kept, the remaining cells compensated the loss well and corneal thickness remains normal.…”

Risk Factors for Endothelial Decompensation after Penetrating Keratoplasty and Its Novel Therapeutic Strategies

“…Owing to the two properties of corneal endothelial cells, their function as a sodium pump to maintain transparency, and their lack of regeneration ability, the long-term optical clarity of the cornea after PKP is decided by the number, morphology, and function of donor endothelial cells [23]. However, in the presence of an irreversible ECD decline and dysfunction of the graft endothelium, endothelial decompensation of the PKP graft will occur.…”

“…According to previous studies, the density of endothelial cells after the first ten years following PKP has been reported to be 960 ± 470 [24], 840 ± 150 [25], or 642 ± 166 cells/mm 2 [26], and after the next ten years, the density was 855 [27] or 666 ± 284 cells/mm 2 [26] (Table 2 [3, 8, 9, 15, 23, 24, 26–31]). The speed of endothelial cell loss was highest in the first year after PKP, with a rate of approximately 40% [30].…”

“…The first year after surgery represents early phase endothelial cell loss, and the following years represent the late phase endothelial cell loss [32]. The first biexponential model presented by Armitage et al suggests distinct mechanisms of endothelial decay; the fast component within the first postoperative year that persists for years is ascribed to surgical trauma, and the slow component is imputed to a chronic proapoptotic change due to alteration of the anterior chamber milieu [14, 23, 34]. However, this hypothesis cannot explain the differences in endothelial cell loss and prognosis between patients with keratoconus and bullous keratopathy [34].…”

Construction of a tissue-engineered human corneal endothelium and its transplantation in rabbit models

“…Our results of alizarin red staining displayed that the ECD of the TE-HCE-transplanted rabbit corneas was 2703 ± 70.37 cells/mm 2 on average 358 days after PKP surgery, while that of control corneas was only 2509.90 ± 51.11 cells/mm 2 . The ECD of the TE-HCE-transplanted rabbit cornea was higher than that of the corneas in TE-HCE-transplanted rabbits and cats in our previous study (Fan TJ et al, 2011;Fan et al, 2013), and much higher than that of the corneas 12 months after endothelial keratoplasty in donated cornea-transplanted patients (<2000 cells/ mm 2 ) (Van Dooren et al, 2004;Kettesy et al, 2014;Lam et al, 2015;Yoeruek et al, 2015). Moreover, our results of H&E staining and SEM and TEM studies revealed that a continuous monolayer of corneal endothelial cells in hexagonal or polygonal morphology attached tightly to the de novo generated DM was reconstructed.…”