Publications by authors named "Tarek Safi"

3 Publications

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Semiquantitative Criteria in the Eye Bank That Correlate with Cornea Guttata in Donor Corneas.

Klin Monbl Augenheilkd 2021 Jun 22;238(6):680-687. Epub 2021 Jun 22.

Department of Ophthalmology, Saarland University Hospital and Saarland University Faculty of Medicine, Homburg, Germany.

Background: Cornea guttata may not be recognized in the eye bank and recent studies have displayed that guttae are transplanted in about 15% of cases in varying severities. The purpose of this study was to establish semiquantitative criteria for the detection of cornea guttata in donor corneas in the eye bank.

Methods: In this retrospective cohort study, preoperative endothelial pictures of donor corneas were collected and classified according to the post-penetrating keratoplasty cornea guttata grade into three distinct groups: group 1 consists of healthy corneas with no guttae (guttata grade 0); group 2 constitutes corneas with mild asymptomatic cornea guttata (guttata grade +); and group 3 comprises corneas with advanced widespread cornea guttata (guttata grade ++/+++/++++). The preoperative pictures of each group were then individually analyzed using the following five semiquantitative criteria: The number and the area of the cell-depleted surfaces, the presence of less than 50% of the cells having a hexagonal or a circular shape, the presence of cell membrane defects and interruptions, the presence of blebs in the cell membrane, and the presence of groups of cells with a distinct whitish color.

Results: In total, 262 patients were included in this study, with a total number of 1582 preoperative donor corneal endothelial pictures. Out of those pictures, groups 1, 2, and 3 encompassed 995 (62.9%), 411 (26.0%), and 176 (11.1%) pictures, respectively. Three out of the five eye bank criteria were found to correlate with postoperative cornea guttata with a highly significant p value of < 0.001. These three criteria are the presence of less than 50% of the cells having a hexagonal or a circular shape, the presence of cell membrane defects and interruptions and, the presence of blebs. The presence of groups of cells with a distinct whitish color was only a weak predictive factor for cornea guttata (p = 0.069). There was no statistically significant correlation between the number and the area of cell-depleted surfaces and postoperative cornea guttata with a p = 0.181.

Conclusion: Three semiquantitative criteria that can be detected in the eye bank using inverted light microscopy seem to correlate with postoperative cornea guttata: The presence of blebs, the presence of cell membrane defects and interruptions, as well as endothelial pictures with less than 50% of the cells having a hexagonal of circular shape. The presence of groups of cells with a distinct whitish color appears to be a weak predictor of cornea guttata.
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http://dx.doi.org/10.1055/a-1498-1846DOI Listing
June 2021

[Excimer laser-assisted DALK: a case report from the Homburg Keratoconus Center (HKC)].

Ophthalmologe 2021 Feb 25. Epub 2021 Feb 25.

Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes (UKS), Kirrbergerstr. 100, Geb. 22, 66421, Homburg/Saar, Deutschland.

Indications: The aim of excimer laser-assisted deep anterior lamellar keratoplasty (excimer-DALK) is, as in mechanical DALK, the treatment of keratectasia (keratoconus and pellucid marginal degeneration), stromal scars or stromal corneal dystrophy. A prerequisite for surgery is the absence of (pre‑) Descemet's scars and an intact endothelium.

Surgical Technique: After excimer laser-assisted trephination to 80% of the corneal thickness at the trephination site, intrastromal air injection (so-called big bubble) and lamellar corneal preparation, a lamellar anterior transplantation of the endothelium-free donor tissue is performed. The technique combines the advantages of DALK and excimer laser trephination. We describe the steps of an excimer-DALK from the Homburg Keratoconus Center (HKC).

Conclusion: Excimer-DALK is a viable treatment option for patients with intact endothelium. In cases of intraoperative perforation, conversion to excimer-perforating keratoplasty (PKP) with all the advantages of excimer laser trephination remains feasible.
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http://dx.doi.org/10.1007/s00347-021-01342-3DOI Listing
February 2021

Reproducibility of Non-Invasive Endothelial Cell Loss Assessment of the Pre-Stripped DMEK Roll After Preparation and Storage.

Am J Ophthalmol 2021 01 11;221:17-26. Epub 2020 Aug 11.

Department of Ophthalmology, Saarland University Medical Center, Homburg, Germany.

Purpose: To present a novel, reproducible, and noninvasive method to quantify endothelial cell loss (ECL) of pre-stripped endothelial Descemet membrane lamellae (EDML) caused by its preparation and storage for 5 days.

Design: Prospective laboratory investigation.

Methods: Thirty EDML were stripped from corneoscleral discs and placed in a well plate containing organ culture medium 1 without dextran. An additional 5 corneoscleral discs were also placed in the same medium and served as a control group. Endothelial cell density (ECD) was measured without any additional manipulation by using spectral microscopy following an extensive protocol by which 3 clear images from the center and periphery were used for each measurement, and each measurement was repeated 5 times. ECD was measured before and directly after preparation and on days 1, 2, and 5 of storage.

Results: The average ECD of the 30 corneoscleral discs, which later underwent stripping, was 2,292 ± 308 cells/mm vs 2,129 ± 222 cells/mm for the 5 corneoscleral discs of the control group. The ECL of the control group was significantly lower than that of the EDML group (P < .0001), reaching ±2% versus 11 ± 5%, respectively, on day 0; 3% ± 4% versus 19 ± 10%, respectively, on day 1; 2% ± 2% versus 22% ± 11%, respectively on day 2; and 4% ± 3% versus 23% ± 9%, respectively, on day 5. Reproducibility of the results on all measurement days was good, with Cronbach alpha values ranging from 0.85 to 0.98.

Conclusions: A highly reproducible, noninvasive method was presented for measuring the ECD of the EDML. Prestripped EDML lose a significant amount of cells, up to 11%, due to the preparation process and up to 23% after 5 days of storage. Therefore, shipping them after several days of storage to be used in a DMEK surgery cannot be recommended.
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http://dx.doi.org/10.1016/j.ajo.2020.08.001DOI Listing
January 2021