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Mohamad Dakroub

Bio: Mohamad Dakroub is an academic researcher. The author has contributed to research in topics: Medicine & Strabismus surgery. The author has an hindex of 1, co-authored 2 publications receiving 1 citations.

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TL;DR: The results validate freeze-thawing as a method to generate an extracellular matrix without major structural changes.
Abstract: Background: Porcine eyes have been widely used as ex vivo models in glaucoma research, as they share similar features with human eyes. Freeze-thawing is a non-invasive technique that has been used to obliterate living cells in anterior segment ex vivo cultures, to prepare them for further research such as cellular repopulation. This technique has previously been shown to reduce the intraocular pressure (IOP) in porcine eyes. The aim of this study was to investigate whether freeze-thaw cytoablation causes corresponding canalogram outflow changes in perfused anterior segment cultures (A FT ) and whole porcine eyes (W FT ). We hypothesized that the known IOP drop in A FT after trabecular meshwork ablation by freeze-thaw would be accompanied by a similarly large change in the distal outflow pattern. Methods: Two-dye (fluorescein and Texas red) reperfusion canalograms were used to compare the outflow time before and after two -80°C cycles of freeze-thaw. We assigned 28 freshly enucleated porcine eyes to four groups: perfused anterior segment dye controls (A CO , n = 6), perfused whole eye dye controls (W CO , n = 6), freeze-thaw treated anterior segment cultures (A FT , n = 10), and freeze-thaw treated whole eyes (W FT , n = 6). Results: In control groups A CO and W CO , the two different dyes had similar filling times. In A FT , the outflow pattern and filling times were unchanged. In W FT , the temporal superior quadrant filled more slowly (p = 0.042) while all others remained unchanged. The qualitative appearance of distal outflow spaces was altered only in some eyes. Conclusions: Freeze-thaw cytoablation caused neither loss nor leakage of distal outflow structures. Surprisingly, the loss of an intact trabecular meshwork over the entire circumference did not result in a general acceleration of quadrant outflow times. The results validate freeze-thawing as a method to generate an extracellular matrix without major structural changes.

1 citations

Posted ContentDOI
20 Sep 2021
TL;DR: A 10% reduction in intraocular pressure after trabeculopuncture can be used as predictor for the success of 180° AIT in porcine eyes in patients with an unidentified distal outflow resistance.
Abstract: Purpose: To investigate trabeculopuncture (TP) for predicting the outcome of ab interno trabeculectomy (AIT). AIT is an effective, low-risk procedure for open angle glaucoma. Despite widespread utilization, it fails in patients with an unidentified distal outflow resistance. Methods: We bisected 81 enucleated porcine eyes and perfused them for 72 hours. They were assigned to two groups: trial (n=42) and control (n=39). Intraocular pressure (IOP) was measured continuously. At 24 hours, four YAG-laser trabeculopunctures on the nasal trabecular meshwork were performed, followed by a 180° AIT at the same site at 48 hours. Eyes were divided into TP and AIT responders and non-responders; the proportion of TP responders between both AIT groups was compared. Results: Both post-TP and post-AIT IOPs were lower than baseline IOP (p=0.015 and p<0.01, respectively). The success rates of TP and AIT were 69% and 85.7%, respectively. The proportion of TP responders among AIT responders was greater than that of AIT non-responders (p<0.01). Sensitivity and specificity values of TP as predictive test for AIT success were 77.7% and 83.3%, respectively. The positive and negative predictive values were 96.6% and 38.5%, respectively. Conclusion: A 10% reduction in IOP after TP can be used as predictor for the success (>20% IOP decrease) of 180° AIT in porcine eyes.
Journal ArticleDOI
TL;DR: This study showed a similar success rate of horizontal strabismus surgery performed in a PC setting by staff surgeons as compared to that performed in an OPD setting by residents at 6 months and 1 year, and a significantly higher success rate was observed at long term follow-up in the PC group compared to the OPD group.
Abstract: ABSTRACT Purpose To compare the long-term surgical outcomes of patients with horizontal strabismus whose surgery was performed in an outpatient department (OPD) setting (by residents-in-training) to those whose surgery was performed in a private clinic (PC) setting (by staff-ophthalmologists) in the same operating room/institution. Methods Two hundred and forty-four patients’ charts who had horizontal strabismus surgeries from January 2007 to 2020 were reviewed retrospectively. A total of 92 patients were operated on by residents and followed in OPD, and 152 patients by staff-surgeons and followed in PC. Demographic data and eye exam parameters were collected. Distance and near deviation (in prism diopters, PD) were extracted and compared between groups at baseline and postoperatively (6 months and yearly for up to 6 years). Success was defined as a postoperative motor alignment of 10PD or less. Results The mean age of the 244 patients was 10.5 ± 11.7 years, with no significant differences between groups. A longer follow-up duration was reported in the PC group (34.9 ± 24.3 months vs 25.3 ± 20.2 months). Patients had similar success rates in both groups in the early postoperative period (6 months and 1 year); however, a higher success rate was observed in the PC group compared to OPD at 3, 5 and 6 years with the following respective values: 72.2% vs 50% (p < .001), 75% vs. 66.7% (p = .02), and 68.6% vs. 66.7% (p = .03). The difference was more pronounced in the esotropia subgroup mostly at 3 years follow-up. Conclusion This study showed a similar success rate of horizontal strabismus surgery performed in a PC setting by staff surgeons as compared to that performed in an OPD setting by residents at 6 months and 1 year. A significantly higher success rate was observed at long term follow-up (after 2 years) in the PC group compared to the OPD group, possibly related to the difference in compliance with post-operative follow-up management and not to surgery itself.
Journal ArticleDOI
TL;DR: A younger age at presentation and absence of amblyopia were positively correlated with surgical success in the partially accommodative esotropia group, and the overall surgical success rate for horizontal strabismus surgery was 72.67% with the 3 subgroups having similar success rates.
Journal ArticleDOI
TL;DR: In this paper , the authors investigated whether trabeculopuncture (TP) could detect distal outflow resistance to predict the outcome of canal-based glaucoma surgery such as ab interno trabo-culectomy (AIT) and concluded that a 10% reduction in IOP after TP can be used as a predictor for the success of 180° AIT in porcine eyes.
Abstract: We investigated whether trabeculopuncture (TP) could detect distal outflow resistance to predict the outcome of canal-based glaucoma surgery such as ab interno trabeculectomy (AIT). These procedures have a high utilization in open angle glaucoma, but fail in eyes with an unidentified distal outflow resistance. We assigned 81 porcine eyes to two groups: trial (n = 42) and control (n = 39). At 24 h, four YAG-laser trabeculopunctures were placed nasally, followed by a 180° AIT at the same site at 48 h. The proportion of TP responders between both AIT groups was compared. Histology and outflow canalograms were determined. Both post-TP and post-AIT IOPs were lower than baseline IOP (p = 0.015 and p < 0.01, respectively). The success rates of TP and AIT were 69% and 85.7%, respectively. Sensitivity and specificity values of TP as predictive test for AIT success were 77.7% and 83.3%, respectively. The positive and negative predictive values were 96.6% and 38.5%, respectively. We conclude that a 10% reduction in IOP after TP can be used as a predictor for the success (> 20% IOP decrease) of 180° AIT in porcine eyes.

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TL;DR: In this article, a program was developed to automatically compute focal flow fits for each macropixel and to detect convergent perilimbal flow patterns with macropixels grouped into 3 equal-radial width rings around the cornea.
Abstract: Purpose To visualize and quantify conventional outflow directly in its anatomic location. Methods We obtained fluorescein canalograms in six porcine whole eyes and six porcine anterior segment cultures. Eyes were perfused with a constant pressure of 15 mmHg using media containing 0.017 mg/ml fluorescein. Flow patterns were visualized using a stereo dissecting microscope equipped for fluorescent imaging. Images were captured every 30 seconds for 20 minutes for time lapse analysis. Anterior chamber cultures were imaged again on day three of culture. Canalograms were first analyzed for filling time per quadrant. We then wrote a program to automatically compute focal flow fits for each macropixel and to detect convergent perilimbal flow patterns with macropixels grouped into 3 equal-radial width rings around the cornea. A generalized additive model was used to determine fluorescence changes of individual macropixels. Results The resulting imaging algorithm deployed 1024 macropixels that were fit to determine maximum intensity and time to fill. These individual fits highlighted the focal flow function. In whole eyes, significantly faster flow was seen in the inferonasal (IN) and superonasal (SN) quadrants compared to the superotemporal (ST) and inferotemporal (IT) ones (p<0.05). In anterior chamber cultures, reduced flow on day 1 increased in all quadrants on day 3 except in IT (p<0.05). Perilimbal ring analysis uncovered convergent perilimbal flow. Conclusions An algorithm was developed that analyzes regional and circumferential outflow patterns. This algorithm found flow patterns that changed over time and differ in whole eyes and anterior segment cultures.

42 citations