Curcumin protects against NMDA-induced toxicity: A possible role for NR2A subunit

PURPOSE. Curcumin, a phenolic compound extracted from the rhizome of Curcuma longa, was found to attenuate NMDAinduced excitotoxicity in primary retinal cultures. This study was conducted to further characterize curcumin neuroprotective ability and analyze its effects on NMDA receptor (NMDAr). METHODS. NMDAr modifications were analyzed in primary retinal cell cultures using immunocytochemistry, whole-cell patch-clamp recording and western blot analysis. Cell death was evaluated with the TUNEL assay in primary retinal and hippocampal cultures. Optical fluorometric recordings with Fura 2-AM were used to monitor [Ca 2ϩ ] i . RESULTS. Curcumin dose-and time-dependently protected both retinal and hippocampal neurons against NMDA-induced cell death, confirming its anti-excitotoxic property. In primary retinal cultures, in line with the observed reduction of NMDAinduced [Ca 2ϩ ] i rise, whole-cell patch-clamp experiments showed that a higher percentage of retinal neurons responded to NMDA with low amplitude current after curcumin treatment. In parallel, curcumin induced an increase in NMDAr subunit type 2A (NR2A) level, with kinetics closely correlated to time-course of neuroprotection and decrease in [Ca 2ϩ ] i . The relation between neuroprotection and NR2A level increase was also in line with the observation that curcumin neuroprotection required protein synthesis. Electrophysiology confirmed an increased activity of NR2A-containing NMDAr at the plasma membrane level. CONCLUSIONS. These results confirm the neuroprotective activity of curcumin against NMDA toxicity, possibly related to an increased level of NR2A, and encourage further studies for a possible therapeutic use of curcumin based on neuromodulation of NMDArs. (Invest Ophthalmol Vis Sci

Pentacam Assessment of Posterior Lamellar Grafts to Explain Hyperopization after Descemet's Stripping Automated Endothelial Keratoplasty

Purpose: To evaluate changes in posterior corneal curvature as a possible cause of the hyperopic refractive shift observed after Descemet's stripping automated endothelial keratoplasty (DSAEK). Design: Prospective, noncomparative, interventional case series. Participants: Thirty-four eyes of 29 patients with Fuchs' endothelial dystrophy or pseudophakic bullous keratopathy. Methods: A standard DSAEK procedure was performed in 34 eyes using the pull-through technique for graft delivery. When cataract was present (n = 7), phacoemulsification with posterior chamber intraocular lens implantation was combined. Each eye underwent Pentacam (Oculus, Wetzlar, Germany) evaluation 1, 3, and 12 months after surgery. Corneal graft thickness was calculated on Scheimpflug scans at 9 locations (1 central, 4 peripheral, and 4 mid peripheral). The mean radius of posterior corneal curvature (Rm) was recorded. At each postoperative examination time, manifest refraction was determined and compared with pre-DSAEK values in simple procedures or with intended postoperative refraction, if cataract surgery had been performed. Main Outcome Measures: Manifest refraction, Rm, and corneal graft thickness at 1, 3, and 12 months after surgery. Results: The mean±standard deviation posterior corneal curvature was 6.5±0.56 mm before surgery and varied from 5.52±0.39 mm 1 month after surgery to 5.83±0.37 mm at 3 months after surgery and 5.92±0.35 mm at 12 months after surgery. The grafts were significantly thicker in the periphery and mid periphery than in the center at all examination times. Thickening diminished significantly over time at all locations. The average reduction of corneal thickness was higher at the edges (91.5 μm) than in the mid periphery (38.3 μm) or in the center (24.2 μm). The average postoperative spherical equivalent±standard deviation changed from -0.31±2.35 diopters (D) before surgery to 1.03±2.21 D 1 month after surgery, 0.61±2.07 D 3 months after surgery, and +0.31±2.03 D 12 months after surgery. Conclusions: The difference in thickness between center and periphery of the DSAEK graft induces a change in posterior corneal curvature, resulting in a hyperopic shift that decreases with time and is negligible for spectacle correction. However, when performing a triple procedure, intraocular lens selection should take into account the refractive change induced by DSAEK. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. © 2009 American Academy of Ophthalmology

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Surgical technique for graft exchange after big-bubble deep anterior lamellar keratoplasty

Purpose: The aim of this study was to describe a surgical technique for repeat deep anterior lamellar keratoplasty (DALK) by baring Descemet membrane again in eyes affected by stromal opacity of the donor lamella. Methods: Repeat DALK was performed in 5 eyes of 5 patients affected by central stromal opacity not involving the endothelium; indications for repeat surgery were postbacterial or postherpetic corneal scars (n = 3), postphotorefractive keratectomy haze (n = 1), and recurrence of granular dystrophy (n = 1). The surgical procedure consisted of the following: (1) superficial trephination, 250 mm in depth, on the original peripheral scar; (2) blunt detachment of the donor graft completed by means of corneal forceps; (3) apposition of the new lamella. Best spectacle-corrected visual acuity, topographic astigmatism, and endothelial cell density were evaluated preoperatively, as well as 3, 6, 9, 12, and 18 months after surgery. Results: At the latest follow-up examination, with all sutures removed from all eyes, the best spectacle-corrected visual acuity was 20/30 or better in all cases with 3 eyes achieving 20/20. Postoperative refractive astigmatism averaged 3.0 6 1.2 diopters (mean 6 SD); endothelial cell density was not significantly affected by surgery. Conclusions: Repeat DALK is effective in removing diseased corneal stroma while keeping the recipient endothelium unaffected; the procedure is simple and does not require pneumatic dissection, thus eliminating the most challenging surgical step; postoperative visual recovery does not differ from that experienced after primary DALK

Anterior segment optical coherence tomography-guided big-bubble technique

Purpose: To evaluate the feasibility of intraoperative anterior segment (AS) optical coherence tomography (OCT) for quantification of the corneal depth reached with the dissecting cannula used for deep anterior lamellar keratoplasty, as well as its correlation with the success rate of big-bubble formation. Design: Retrospective, noncomparative, interventional case series. Participants: One hundred consecutive keratoconus patients. Intervention: Deep anterior lamellar keratoplasty was performed using the big-bubble technique. During surgery, the cannula used for pneumatic dissection was inserted into the peripheral stroma and advanced as deep and far toward the center as believed adequate by the surgeon. Then, after retracting the cannula, AS OCT was performed. The cannula was placed back in position and creation of the big bubble was attempted. Main Outcome Measures: Stromal depth reached with the cannula tip, success rate in achieving big-bubble formation, and complication rate. Results: Bubble formation was obtained in 70 of 100 eyes (70%). In all remaining eyes, the procedure was completed by manual deep lamellar dissection. The average depth reached by the cannula tip was 104.3±34.1 μm from the internal corneal surface; the mean value recorded in cases of successful big-bubble formation (90.4±27.7 μm) was statistically lower than that measured in failed procedures (136.7±24.2 μm). In 1 case, corneal perforation occurred during the insertion of the cannula and required conversion to penetrating keratoplasty (PK). In 8 eyes, small microperforations occurred during stromal excision but could be managed conservatively, avoiding conversion to PK. In 2 advanced cones, an incomplete bubble formation was obtained, necessitating manual peripheral stromal removal. Conclusions: Successful big-bubble formation can be anticipated if pneumatic dissection is attempted at a sufficiently deep level. Although an ideal depth could not be defined, AS OCT allows objective evaluation of the depth reached by the cannula tip used for pneumatic dissection. The AS OCT findings may confirm the decision to proceed with air injection. It is possible that cannula repositioning based on the AS OCT depth may improve the success rate for big-bubble formation. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. © 2013 American Academy of Ophthalmology

Inadvertent donor button inversion during big-bubble deep anterior lamellar keratoplasty

Purpose: The aim of this study was to describe clinical outcomes and histopathologic findings in a case of repeat deep anterior lamellar keratoplasty (DALK) performed because of inadvertent inversion of the donor button at the time of primary surgery.Methods: A 34-year-old woman underwent big-bubble DALK for keratoconus in her right eye; 4 days postoperatively, slit-lamp examination revealed the presence of several inclusions in the interface, whereas anterior segment optical coherence tomography (AS-OCT) showed pathologically marked wrinkling of the posterior stroma; inadvertent intraoperative inversion of the graft was diagnosed and the interface inclusions were assumed to be of epithelial origin. Repeat surgery was performed: donor tissue was removed and submitted to histological examination, marking the external surface of the lamella; the recipient residual bed was carefully washed and a new lamellar graft was sutured into position. Three months postoperatively, the patient underwent a complete ophthalmologic examination, including best-spectacle corrected visual acuity testing, refraction, biomicroscopy, AS-OCT, and endothelial microscopy.Results: Histological examination confirmed that the donor button had been implanted with the epithelium facing the residual bed. Three months postoperatively, normal corneal curvature was visible at AS-OCT, the best-spectacle corrected visual acuity was 20/25, and the interface appeared perfectly clear. Endothelial cell density had not been substantially affected by the 2 surgical procedures.Conclusions: Inadvertent inversion of donor tissue at the time of DALK is reported for the first time. Prompt exchange of the lamellar graft was instrumental in avoiding epithelial colonization of the interface, as well as in restoring excellent vision

Red Reflex-Guided Big-Bubble Deep Anterior Lamellar Keratoplasty: A Simple Technique to Judge Dissection Depth

Purpose: To report the results of a modified big-bubble deep anterior lamellar keratoplasty technique using the intraoperative red reflex to visualize the amount of residual stroma beneath the inserted cannula. Methods: A total of 132 consecutive keratoconic eyes were included in this retrospective, noncomparative, interventional case series. Before starting surgery, pharmacologic mydriasis was induced in all eyes undergoing a big-bubble deep anterior lamellar keratoplasty procedure. After partial trephination of the recipient cornea, a spatula was inserted at the base of the incision and advanced into depth using as a reference the thin dark line seen in the red reflex ahead of the advancing tip; the stromal depth reached was measured using anterior segment optical coherence tomography. Finally, the spatula was exchanged for a 27-gauge cannula, and air was injected to create a big bubble. The stromal depth reached with the spatula, success rate of big-bubble formation, and complications were recorded. Results: The big bubble was obtained in 118 of 132 eyes (89.4%). Of the remaining 14 eyes, 11 underwent completion of the procedure by manual dissection and 3 were converted to penetrating keratoplasty because the bubble burst while trying to enlarge it. Perforation did not occur in any case during cannula insertion. The average thickness reached with the stromal dissection was 64.3 ± 19.5 m. Conclusions: The thin dark line, seen in the red reflex obtained with pharmacologic dilation, provides a useful and effective reference that can be used to visualize and judge the depth of dissection, thus allowing a safer and reproducible approach to the pre-Descemetic stroma. Â