Effect of retinol dehydrogenase gene transfer in a novel rat model of Stargardt disease.

Dysfunction of the ATPase-binding Cassette Transporter protein (ABCA4) can lead to early onset macular degeneration, in particular to Stargardt disease. To enable translational research into this form of blindness, we evaluated the effect of Cas9-induced disruptions of the ABCA4 gene to potentially generate new transgenic rat models of the disease. We show that deletion of the short exon preceding the second nucleotide-binding domain is sufficient to drastically knock down protein levels and results in accumulation of retinoid dimers similar to that associated with Stargardt disease. Overexpression of the retinol dehydrogenase enzymes RDH8 and RDH12 can to a limited extent offset the increase in the bisretinoid levels in the Abca4Ex42-/ - KO rats possibly by restricting the time window in which retinal can dimerize before being reduced to retinol. However, in vivo imaging shows that overexpression of RDH8 can induce retinal degeneration. This may be due to the depletion in the outer segment of the cofactor NADPH, needed for RDH function. The translational potential of RDH therapy as well as other Stargardt disease therapies can be tested using the Abca4 knockdown rat model.

[Refractive outcome and prognostic factors for success of intracorneal ring segment implantation in keratoconus: A retrospective study of 75 eyes]. / Résultats réfractifs et facteurs pronostiques de succès du traitement du kératocône par anneaux intracornéens : étude rétrospective sur 75 yeux.

PURPOSE: To define the prognostic factors for success and to evaluate the predictability of intracorneal ring segments (ICRS) in the treatment of keratoconus. METHODS: In this retrospective study conducted at the University Hospital of Nantes, Keraring ICRS were implanted in 75 eyes of 65 patients with keratoconus. Best spectacle corrected visual acuity (BSCVA), manifest refraction and corneal topography were analysed. To define prognostic factors, we compared the results of 2 groups: "IMP" (gain of at least 2 lines of BSCVA) and "ROS" (the others). We evaluated the predictability of the nomogram with a mathematical model proposed by Pena-Garcia et al. (IOVS 2012). RESULTS: At 3 months, BSCVA improved from 0.3 to 0.2 logMAR (P<0.05). A total of 61 % of the patients experienced a gain of at least 1 line of BSCVA. Spherical equivalent decreased by 2.32 diopters (D), cylinder decreased by 2.47 D, and maximal keratometry by 2.62 D (P<0.05 for each compared with preoperative values). A total of 90 % of the patients whose BSCVA did not improve achieved a significant refractive improvement. A preoperative BSCVA>0.3 logMAR is a prognostic factor for gain of at least 2 lines of BSCVA (P=1.6E-3). Predictability was fair: only 43 % had a±1D difference from the spherical equivalent predicted by the nomogram. There was no statistically significative difference between gain or loss of BSCVA predicted by the mathematical model and the postoperative results. CONCLUSIONS: ICRS are visually and refractively effective. Predictability could be improved by using mathematical models and knowledge of prognostic factors for success, allowing for better patient selection.

Long-term expression of melanopsin and channelrhodopsin causes no gross alterations in the dystrophic dog retina.

Several preclinical studies have investigated the potential of algal channelrhodopsin and human melanopsin as optogenetic tools for vision restoration. In the present study, we assessed the potentially deleterious effects of long-term expression of these optogenes on the diseased retina in a large animal model of retinal degeneration, the RPE65-deficient Briard dog model of Leber congenital amaurosis. Intravitreal injection of adeno-associated virus vectors expressing channelrhodopsin and melanopsin had no effect on retinal thickness over a 16-month period post injection. Our data support the safety of the optogenetic approach for the treatment of blindness.

[Comparison of anatomic and functional results between Z6 femtosecond laser assisted and manual trephination in deep anterior lamellar keratoplasty for advanced keratoconus [French version]]. / Comparaison des résultats anatomiques et fonctionnels à 12 mois d'une série de kératoplasties lamellaires profondes assistées au laser femtoseconde Z6 versus trépanation manuelle pour kératocônes sévères.

The management of severe keratoconus requires corneal transplantation, for which the gold standard is deep anterior lamellar keratoplasty (DALK), preserving the healthy Descemet's membrane and endothelium. The safety and reproducibility of corneal cuts have been improved by the evolution of femtosecond lasers in refractive surgery, and femtosecond laser in DALK would seem to provide the same advantages over the manual method. In our retrospective study, we compare functional and anatomical results of femtosecond assisted DALK versus manual trephination DALK in patients with keratoconus in stage 4 of the Krumeich classification. It is a retrospective study including all patients with stage 4 keratoconus who underwent femtosecond laser assisted DALK between November 2012 and November 2015 in Nantes hospital. We compared those patients to a group of patients who underwent manual DALK in the same period, paired by age and maximal keratometry. We assessed visual acuity, pachymetry, endothelial cell density (specular microscopy), and keratometry before surgery and at 4, 8 and 12 months of follow-up. Laser settings and intraoperative complications were recorded. Nineteen patients underwent surgery by femtosecond assisted DALK, 6 women and 12 men with average age 30.2±10.8 years at transplantation. They were paired with a group of 17 patients who underwent manual DALK in order to compare results. Before surgery, mean visual acuity in the femtosecond group was 0.90 logMAR versus 0.89 logMAR in the manual group, showing no statistically significant difference (P=0.96). Both groups were similar in terms of preoperative age, mean keratometry, pachymetry and endothelial cell density. Average visual acuity post-surgery was 0.27, 0.26; and 0.14 logMAR for femtosecond DALK versus 0.27, 0.17 et 0.25 for manual DALK at 4, 8 and 12 months follow-up, respectively showing no statistically significant difference. After surgery, at 4, 8 and 12 months, mean pachymetry was similar in both groups, and average endothelial cell density was 2390 cells/mm2 in femtoDALK versus 2531 cells/mm2 in manual DALK at 12 months of follow-up, showing no statistically significant difference (P=0.5726). The rate of Descemet's membrane microperforations during the procedure was low and similar for both groups. Our study allows for a 12 month follow-up, with assessment of visual recovery, anatomical result and endothelial safety in a sample of 19 femtosecond laser assisted DALK with no statistical significant difference versus the manual trephination group. Femtosecond laser allows for increased reproducibility of the DALK procedure without reducing adverse effects during surgery. Femtosecond laser seems to improve the technique of the DALK procedure, and future developments could improve the reproducibility of DALK even further. A medical economics study would be necessary to determine the cost effectiveness of femtosecond laser assisted DALK.

Comparison of 12-month anatomic and functional results between Z6 femtosecond laser-assisted and manual trephination in deep anterior lamellar keratoplasty for advanced keratoconus.

The management of severe keratoconus requires corneal transplantation, for which the gold standard is deep anterior lamellar keratoplasty (DALK), preserving the healthy Descemet's membrane and endothelium. The safety and reproducibility of corneal cuts have been improved by the evolution of femtosecond lasers in refractive surgery, and femtosecond laser in DALK would seem to provide the same advantages over the manual method. In our retrospective study, we compare functional and anatomical results of femtosecond-assisted DALK versus manual trephination DALK in patients with keratoconus in stage 4 of the Krumeich classification. It is a retrospective study including all patients with stage 4 keratoconus who underwent femtosecond laser-assisted DALK between November 2012 and November 2015 in Nantes university medical center. We compared those patients to a group of patients who underwent manual DALK in the same period, paired by age and maximal keratometry. We assessed visual acuity, pachymetry, endothelial cell density (specular microscopy), and keratometry before surgery and at 4, 8 and 12 months of follow-up. Laser settings and intraoperative complications were recorded. Nineteen patients underwent surgery by femtosecond-assisted DALK, 6 women and 12 men with average age 30.2±10.8 years at transplantation. They were paired with a group of 17 patients who underwent manual DALK in order to compare results. Before surgery, mean visual acuity in the femtosecond group was 0.90 logMAR versus 0.89 logMAR in the manual group, showing no statistically significant difference (P=0.96). Both groups were similar in terms of preoperative age, mean keratometry, pachymetry and endothelial cell density. Average visual acuity post-surgery was 0.27; 0.26; and 0.14 logMAR for femtosecond DALK versus 0.27; 0.17 et 0.25 for manual DALK at 4, 8 and 12 months follow-up respectively, showing no statistically significant difference. After surgery, at 4, 8 and 12 months, mean pachymetry was similar in both groups, and average endothelial cell density was 2390 cells/mm2 for femto DALK versus 2531 cells/mm2 for manual DALK at 12 months of follow-up, showing no statistically significant difference (P=0.5726). The rate of Descemet's membrane microperforations during the procedure was low and similar for both groups. Our study allows for a 12-month follow-up, with assessment of visual recovery, anatomic result and endothelial safety in a series of 19 femtosecond laser-assisted DALK with no statistical significant difference versus the manual trephination group. Femtosecond laser allows for increased reproducibility of the DALK procedure without reducing adverse effects during surgery. Femtosecond laser seems to improve the technique of the DALK procedure, and future developments could improve the reproducibility of DALK even further. A medical economics study would be necessary to determine the cost-effectiveness of femtosecond laser-assisted DALK.

[Excimer laser-assisted lamellar endothelial keratoplasty (ExALEK): Technique and results]. / Greffe lamellaire endothéliale assistée au laser Excimer (ExALEK) : technique et résultats.

INTRODUCTION: The purpose of this study is to describe a technique for thin endothelial lamellar keratoplasty and to present the results for endothelial transplant performed at the University Hospital of Nantes. MATERIALS AND METHODS: This paper is a retrospective, single-center descriptive study conducted at the University Hospital of Nantes from September 2010 to May 2014, at first for anatomical or analgesic indications (group 1) and then extended to visual indications (group 2). Patients were followed for 12 months. The preparation of the endothelial graft includes an excimer-laser ablation of the residual stromal bed after lamellar keratectomy by manual deep anterior approach. RESULTS: Seventy surgeries were analyzed. The etiologies were mainly Fuchs Dystrophy, secondary endothelial dystrophy and post-penetrating keratoplasty endothelial failure. Fifty-three patients were integrated in group 1 and seventeen patients in group 2. In group 1, the mean VA at 12 months was 0.70 ± 0.30 Log MAR (0.2 decimal equivalent). In group 2, the mean VA at 12 months was 0.28 ± 0.12 Log MAR (0.5 decimal equivalent). Pachymetry decreased from 740 ± 125.1 µm preoperatively to 613.4 ± 73.4 µm at 12 months. The average central thickness of the graft was 84.1 ± 28.9 µm at 1 month and 80.2 ± 29.4 µm at 12 months. CONCLUSION: The advantage of this new surgical technique is that it is a rapid and repeatable method allowing thin grafts with satisfactory functionality and easy handling. Its performance independent of the scheduled surgery, allows for predictable organization in the operating room.