Bogdan Spiru, IVOS 2017

Biomechanical Differences Between Femtosecond Lenticule Extraction (FLEx) and Small Incision Lenticule Extraction (SmILE) Tested by 2D-Extensometry in Ex Vivo Porcine Eyes Bogdan Spiru; Sabine Kling; Farhad Hafezi; Walter Sekundo 

Investigative Ophthalmology & Visual Science May 2017, Vol.58, 2591-2595. doi:10.1167/iovs.16-20211

 

Abstract

Purpose: To evaluate the biomechanical stability of ex vivo porcine corneas after femtosecond lenticule extraction (FLEx) and small incision lenticule extraction (SmILE) refractive surgeries.

Methods: Forty-five porcine eyes were equally divided into three groups: Groups 1 and 2 were treated with FLEx and SmILE procedure, respectively. Group 3 served as control. A refractive correction of −14 diopters (D) with a 7-mm zone using either a 160-μm flap (FLEx) or a 160-μm cap (SmILE) was performed. For two-dimensional (2D) elastic and viscoelastic biomechanical characterization, two testing cycles (preconditioning stress–strain curve from 1.27 to 12.5 N, stress–relaxation at 12.5 N during 120 seconds) were conducted. Young's modulus and Prony constants were calculated.

Results: At 0.8% of strain, FLEx (370 ± 36 kPa) could resist a significantly lower stress than SmILE (392 ± 19 kPa, P = 0.046) and the control group (402 ± 30 kPa, P = 0.013). Also, FLEx (46.1 ± 4.5 MPa) had a significantly lower Young's modulus than the control group (50.2 ± 3.4 MPa, P = 0.008). The Young's modulus of SmILE (48.6 ± 2.5 MPa) had values situated between untreated corneas and FLEx-treated corneas. When compared to untreated controls, the stress resistance decreased by 8.0% with FLEx and 2.5% with SmILE; Young's modulus decreased by 5.1% with FLEx and 1.04% with SmILE. With a cap-based procedure, both anterior cap and stromal bed carry the intraocular pressure, while in a flap-based procedure, only the stromal bed does.

Conclusions: Compared to flap-based procedures like FLEx, the cap-based technique SmILE can be considered superior in terms of biomechanical stability, when measured experimentally in ex vivo porcine corneas.

M. Regnier, et al. 2017 Medicine (2017)

Eye bank prepared versus surgeon cut endothelial graft tissue for Descemet membrane endothelial keratoplasty: An observational study. 

 

The purpose of this article is to examine outcomes of Descemet membrane endothelial keratoplasty (DMEK) performed with cornea bank (CB) prestripped tissue and surgeon stripped tissue (SST).This retrospective study examined subjects who underwent DMEK with CB or surgeon prepared tissue for Fuchs endothelial corneal dystrophy. Best-corrected visual acuity (BCVA), corneal thickness, endothelial cell count (ECC), and complications were examined before and throughout a 6-month postoperative period.Eleven CB and 22 SST subjects were included. Six months after surgery, BCVA was 20/20 or better in 36.4% of CB and 22.7% of SST subjects (P = .43). Median logMAR BCVA was 0.10 (0.00-0.20, 20/25) in group CB and 0.10 (0.10-0.30, 20/25) in group SST. Median preoperative corneal thickness was 614.0 μm (577.5-662.0 μm) and 658.0 μm (606.0-689.0 μm) in CB and SST subjects, respectively (P = .37). Six months after surgery, median corneal thickness was lower in the CB group (571.0 μm [478.0-592.0 μm]), than in the SST group (576.0 μm [531.0-607.0 μm], P = .02). At 6 months, median ECC was 1500.0 cell/mm (1321.5-2049.0 cell/mm, 41% decrease) in group CB and 1403.0 cell/mm (972.5-2010.7 cell/mm, 46% decrease) in group SST (P = .70). Rebubbling was required in 5 CB (45.5%) and 15 SST (68.2%) subjects (P = .39).Fuchs' dystrophy patients have good anatomic and functional DMEK results. Similar outcomes and complication rates occurred with eye bank and surgeon prepared donor tissue.

An-Katrien De Roo et al, ivos 2017

Identification of Circulating Fibrocytes and Dendritic Derivatives in Corneal Endothelium of Patients With Fuchs’ Dystrophy

 

PURPOSE. Fuchs’ endothelial corneal dystrophy (FECD) is a degenerative eye disorder affecting 4% of Americans older than 40. It is the leading indication for corneal endothelial (CE) transplantation for which there is a global donor shortage. This study aimed to gain further insight into the pathophysiology of FECD and identify targets for nonsurgical therapy.

METHODS. CE from patients with late-onset FECD was compared with that of normal controls using microarray expression analysis (n ¼ 4 FECD, n ¼ 4 normal), reverse transcriptase quantitative PCR (n ¼ 9 FECD, n ¼ 8 normal), and immunohistology (n ¼ 55 FECD, n ¼ 15 normal).

RESULTS. This led to the identification of circulating fibrocytes and their dendritic derivatives in all examined CE samples with FECD (in all clinical stages of symptomatic FECD and independent of prior cataract surgery). These cells were not present in normal CE. In this study we characterize their morphology, protein expression profile, number, and localization within the CE layer of patients with FECD.

CONCLUSIONS. Circulating fibrocytes and their dendritic derivatives are a new aspect of FECD that deserves further investigation. Because they are known to cause fibrosis in a variety of organs, they may play a similar role in FECD and might be a valuable target for nonsurgical therapy. Keywords: Fuchs’ endothelial corneal dystrophy, circulating fibrocytes, dendritic cells, fibrosis, epithelial-mesenchymal transition

ЕX VIVO EXPANDED LIMBAL STEM CELLS

ЛИМБАЛНА БИОПСИЯ След получаване на информирано съгласие бе проведена минимално инвазивна лимбална биопсия. Процедурата включва внимателна дисекция на лимбален епител с размер 2х2 мм в зона с демонстративни палисади на Vogt на 12 ч. при стриктно спазване на асептични условия. В два от случаите за донор бе използвано контралатералното здраво око. При другите двама пациенти биопсията бе получена от зона със запазени палисади на засегнатото око. Полученият материал бе транспортиран до тъканна банка Биорегенерация в среда Stem α 2 (STEM ALPHA, Rhône-Alpes, France).

 

ЕX VIVO EXPANDED LIMBAL STEM CELLS – THERAPEUTIC APPLICATION R. Hristova, Y. Zdravkov, M. Hristova, I. Tanev

 

The aim of the current study is to investigate the application of autologous ex vivo expanded limbal stem cell transplantation in the management of ocular surface disease. This is the fi rst study in Bulagria in which autologous ex vivo expanded stem cells were transplanted to four patients with mean age 56.5 years from the Department of Ophthalmology, University Hospital Alexandrovska. All patients presented signs of unilateral limbal stem cell defi ciency, associated with trophic disease of the ocular surface. After informed consent was obtained a minimally invasive limbal biopsy was performed. The limbal materials were cultured using a novel protocol without additional xenobiotic products. The grafts were transplanted after fourteen days. Anterior segment optical coherence tomography before and after the intervention was used for assessment of the condition. Success of the procedure was defi ned as 1  . complete epithelialization of the corneal surface, 2. partial or complete reduction of neovascularization, 3. achieving normal corneal transparency, thickness and refl ex, 4. visual acuity improvement. Clinical recovery was observed in all patients, as well as improvement of subjective ocular comfort. In three of the cases all four success criteria were met. Visual acuity of one patient did not change, due to neoplastic process, pervading the optic nerve. No graft rejection reactions were observed. Limbal biopsy did not induce limbal stem cell defi ciency in the donor eye. Transplantation of autologous ex vivo expanded limbal stem cells is an effective and safe method for ocular surface reconstruction, which can be applied in different conditions, associated with limbal stem cell defi ciency.

Contact address: Rozaliya Hristova, 1 G. Sofi iyski str. Sofi a 1431 е-mail: alleta@abv.bg

G. Ho Wang Yin 2016

Effect of donor graft characteristics on clinical outcomes in Descemet stripping automated endothelial keratoplasty (DSAEK)

 

Introduction

The purpose of our study was to evaluate the progression of lamellar corneal grafts after endothelial keratoplasty by Descemet stripping automated endothelial keratoplasty (DSAEK) and the effect of their characteristics on the clinical and functional results.

 

Material and methods

This was a prospective study in which 74 patients who had undergone endothelial keratoplasty by DSAEK were included. The corneal grafts were obtained from a French tissue bank and were delivered in a preservation medium containing a deturgescent agent (Corneajet® or Stemalpha 3®). Pachymetry of the corneal graft was measured ex vivo by ultrasonic pachymetry prior to dissection, then after the 1st or 2nd cut as necessary. Corrected visual acuity in logMAR, total graft pachymetry, measured by anterior segment OCT (Spectralis® HRA+SDOCT, Heidelberg engineering, Inc., Heidelberg, Germany) and corneal density (Pentacam®, Oculus, Inc., Wetzlar, Germany) were obtained for each patient preoperatively, at D5, M1, M3, M6, M9 and M12.

 

Results

Overall, 74 corneal grafts, from donors of mean age 69.7±13.3 years (37 to 92 years) were transplanted into 67 patients aged 70.3±12.1 years. Predissection pachymetry was statistically significantly thicker in the case of short deturgescence time (r=−0.383, P=0.001). For the same deturgescence time, predissection pachymetry was statistically significantly thicker in the Stemalpha 3® medium (691±89μm for Corneajet® vs. 760±100μm for Stemalpha 3®, P=0.01), with the same final pachymetry (168±31μm vs. 166±25μm, P=0.833). Graft pachymetry and total corneal pachymetry decreased significantly between the preoperative measurement and M12 (168±29μm vs. 92±57μm, P=0.0008 et 665±124μm vs. 566±73μm, P=0.027 respectively). Preoperative endothelial cell density (2938±418 cells/mm2) did not correlate with postoperative visual acuity. There was a positive correlation between visual acuity at D5 and donor age (r=0.3, P=0.04). Postoperative visual acuity correlated positively with preoperative visual acuity (P<0.05). Corneal densitometry was statically higher than normal postoperative densitometry. Corneal density at M1 correlated positively with time since obtaining the donor tissue (r=0.373, P=0.043). There was no significant difference between the sub-groups of over or under 130μm. Seven patients experienced graft failure with no statistically significant graft risk factor.

 

Discussion

The preservation medium affects predissection pachymetry with no consequence on clinical results. In our study, preoperative visual acuity and donor age were correlated with visual acuity after DSAEK.

 

Conclusion

Although donor age was associated with better visual acuity at D5, the other donor characteristics had no effect on clinical results.

 

 


 


 

 

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