Prosthetic Visual Acuity with the PRIMA System in Patients with Atrophic Age-related Macular Degeneration at 4 years follow-up

Objective

To assess the efficacy and safety of the PRIMA subretinal neurostimulation system 48-months post-implantation for improving visual acuity (VA) in patients with geographic atrophy (GA) due to age-related macular degeneration (AMD) at 48-months post-implantation.

Design

First-in-human clinical trial of the PRIMA subretinal prosthesis in patients with atrophic AMD, measuring best-corrected ETDRS VA (Clinicaltrials.gov NCT03333954).

Subjects

Five patients with GA, no foveal light perception and VA of logMAR 1.3 to 1.7 in their worse-seeing "study" eye.

Methods

In patients implanted with a subretinal photovoltaic neurostimulation array containing 378 pixels of 100 μm in size, the VA was measured with and without the PRIMA system using ETDRS charts at 1 meter. The system's external components: augmented reality glasses and pocket computer, provide image processing capabilities, including zoom.

Main Outcome Measures

VA using ETDRS charts with and without the system. Light sensitivity in the central visual field, as measured by Octopus perimetry. Anatomical outcomes demonstrated by fundus photography and optical coherence tomography up to 48-months post-implantation.

Results

All five subjects met the primary endpoint of light perception elicited by the implant in the scotoma area. In one patient the implant was incorrectly inserted into the choroid. One subject died 18-months post-implantation due to study-unrelated reason. ETDRS VA results for the remaining three subjects are reported herein. Without zoom, VA closely matched the pixel size of the implant: 1.17 ± 0.13 pixels, corresponding to mean logMAR 1.39, or Snellen 20/500, ranging from 20/438 to 20/565. Using zoom at 48 months, subjects improved their VA by 32 ETDRS letters versus baseline (SE 5.1) 95% CI[13.4,49.9], p<0.0001. Natural peripheral visual function in the treated eye did not decline after surgery compared to the fellow eye (p=0.08) during the 48 months follow-up period.

Conclusions

Subretinal implantation of PRIMA in subjects with GA suffering from profound vision loss due to AMD is feasible and well tolerated, with no reduction of natural peripheral vision up to 48-months. Using prosthetic central vision through photovoltaic neurostimulation, patients reliably recognized letters and sequences of letters,and with zoom it provided a clinically meaningful improvement in VA of up to eight ETDRS lines.

[CRISPR/Cas9: From research to therapeutic application]

For several decades, genome engineering has raised interest among many researchers and physicians in the study of genetic disorders and their treatments. Compared to its predecessors, zinc-finger nucleases (ZFN) and transcription activator-like effectors (TALEN), clustered regularly interspaced short palindromic repeats (CRISPR/Cas9) is currently the most efficient molecular tool for genome editing. This system, originally identified as a bacterial adaptive immune system, is capable of cutting and modifying any gene of a large number of living organisms. Numerous trials using this technology are being developed to provide effective treatment for several diseases, such as cancer, cardiovascular and ophthalmic disorders. In research, this technology is increasingly used for genetic disease modelling, providing meaningful models of relevant studies as well as a better understanding of underlying pathological mechanisms. Many molecular tools are now available to put this technique into practice in laboratories, and despite the technical and ethical issues raised by manipulation of the genome, CRIPSR/Cas9 offers a new breath of hope for therapeutic research around the world.

Volumetric quantification of choroid and Haller's sublayer using OCT scans: An accurate and unified approach based on stratified smoothing

BACKGROUND AND OBJECTIVE

The choroid, a dense vascular structure in the posterior segment of the eye, maintains the health of the retina by supplying oxygen and nutrients, and assumes clinical significance in screening ocular diseases including age-related macular degeneration (AMD) and central serous chorioretinopathy (CSCR). As a technological assist, algorithmic estimation of choroidal biomarkers has been suggested based on sectional (B-scan) optical coherence tomography (OCT) images. However, most such 2D estimation techniques are compute-intensive, yet enjoy limited accuracy and have only been validated on OCT image datasets of healthy eyes. Not surprisingly, fine-scale analyses, including those involving Haller's sublayer, remain relatively rare and unsophisticated. Against this backdrop, we propose an efficient algorithm to quantify desired biomarkers with improved accuracy based on volume OCT scans. Specifically, we attempted an accurate, computationally light volumetric segmentation method involving stratified smoothing to detect choroid and Haller's sublayer.

METHODS

For detecting the various boundaries of the choroid and the Haller's sublayer, we propose a common volumetric method that performs suitable exponential enhancement and maintains smooth spatial continuity across 2D B-scans. Further, we achieve suitable volumetric smoothing by primarily deploying light-duty linear regression, and sparingly using compute-intensive tensor voting, and hence significantly reduce overall complexity. The proposed methodology is tested on five health and five diseased OCT volumes considering various metrics including volumetric Dice coefficient and corresponding quotient measures to facilitate comparison vis-à-vis intra-observer repeatability.

RESULTS

On five healthy and five diseased OCT volumes, respectively, the proposed method for choroid segmentation recorded volumetric Dice coefficients of 93.53 % and 93.30 %, which closely approximate the respective reference observer repeatability values of 95.60 % and 95.49 %. In terms of related quotient measures, our method achieved more than 50 % improvement over a recently reported method. In detecting Haller's sublayer as well, our algorithm records statistical performance closely matching that of reference manual method.

CONCLUSION

Advancing the state-of-the-art, the proposed volumetric segmentation, tested on both healthy and diseased datasets, demonstrated close match with the manual reference. Our method assumes significance in accurate screening of chorioretinal diseases including AMD, CSCR and pachychoroid. Further, it enables generating accurate training data for developing deep learning models for improved detection of choroid and Haller's sublayer.

Simultaneous perception of prosthetic and natural vision in AMD patients

Loss of photoreceptors in atrophic age-related macular degeneration (AMD) results in severe visual impairment. Since the low-resolution peripheral vision is retained in such conditions, restoration of central vision should not jeopardize the surrounding healthy retina and allow for simultaneous use of the natural and prosthetic sight. This interim report, prespecified in the study protocol, presents the first clinical results with a photovoltaic substitute of the photoreceptors providing simultaneous use of the central prosthetic and peripheral natural vision in atrophic AMD. In this open-label single group feasibility trial (NCT03333954, recruitment completed), five patients with geographic atrophy have been implanted with a wireless 2 x 2 mm-wide 30 µm-thick device, having 378 pixels of 100 µm in size. All 5 patients achieved the primary outcome of the study by demonstrating the prosthetic visual perception in the former scotoma. The four patients with a subretinal placement of the chip demonstrated the secondary outcome: Landolt acuity of 1.17 ± 0.13 pixels, corresponding to the Snellen range of 20/460-20/565. With electronic magnification of up to a factor of 8, patients demonstrated prosthetic acuity in the range of 20/63-20/98. Under room lighting conditions, patients could simultaneously use prosthetic central vision and their remaining peripheral vision in the implanted eye and in the fellow eye.

Vitreous cytokine expression profiles in patients with retinal detachment

PURPOSE

To compare the expression profiles of various cytokines and chemokines in vitreous samples from patients with retinal detachment (RD) to those from controls and to analyze their association with various clinical features.

METHODS

In this prospective study, undiluted vitreous fluid was obtained from 41 patients with primary RD and 33 controls with macular hole or vitreomacular traction. A multiplex bead immunoassay was performed to determine the expression of 27 inflammatory mediators.

RESULTS

Eleven mediators were significantly upregulated in the vitreous of RD patients compared with controls, including the following: cytokines IL-1ra, IL-6, IL-7, IL-8, IFN-γ; chemokines CCL2, CCL3, CCL4, CXCL10 and CCL11 and growth factor G-CSF. Correlation analyses showed that levels of IL-1ra, CXCL10, CCL11 and G-CSF were positively correlated to the extent of detachment, while those of IL-1ra and CXCL10 were associated with the duration of detachment. There was also a positive association between the concentrations of CXCL10 and CCL11 and preoperative flare values. Additional analysis revealed that flare values and both CXCL10 and CCL11 levels were significantly higher in eyes with grade B or C proliferative vitreoretinopathy (PVR).

CONCLUSION

Our results confirm that RD induces a marked inflammatory response with a complex cytokine network. We identified proteins specifically linked to several clinical features that might contribute to photoreceptor degeneration and PVR-related redetachment. These proteins may represent potential therapeutic targets for improving the anatomical and functional outcomes of RD surgery.

A novel nonsense variant in REEP6 is involved in a sporadic rod-cone dystrophy case

Rod-cone dystrophy (RCD), also called retinitis pigmentosa, is the most common form of progressive inherited retinal disorders secondary to photoreceptor degeneration. It is a genetically heterogeneous disease characterized by night blindness, followed by visual field constriction and, in most severe cases, total blindness. The aim of our study was to identify the underlying gene defect leading to severe RCD in a 60-year-old woman. The patient's DNA was investigated by targeted next generation sequencing followed by whole exome sequencing. A novel nonsense variant, c.267G>A p.(Trp89*), was identified at a homozygous state in the proband in REEP6 gene, recently reported mutated in 7 unrelated families with RCD. Further functional studies will help to understand the physiopathology associated with REEP6 mutations that may be linked to a protein trafficking defect.

ARL2BP mutations account for 0.1% of autosomal recessive rod-cone dystrophies with the report of a novel splice variant

We report a novel ARL2BP splice site mutation after whole-exome sequencing (WES) applied to a Moroccan family including two sisters affected with autosomal recessive rod-cone dystrophy (arRCD). Subsequent analysis of 844 index cases did not reveal further pathogenic chances in ARL2BP indicating that mutations in ARL2B are a rare cause of arRCD (about 0.1%) in a large cohort of French patients.

High speed optical holography of retinal blood flow

We performed noninvasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (∼30 microns diameter) over 400×400  pixels with a spatial resolution of ∼8 microns and a temporal resolution of ∼6.5  ms.

Next-generation sequencing confirms the implication of SLC24A1 in autosomal-recessive congenital stationary night blindness

Congenital stationary night blindness (CSNB) is a clinically and genetically heterogeneous retinal disorder which represents rod photoreceptor dysfunction or signal transmission defect from photoreceptors to adjacent bipolar cells. Patients displaying photoreceptor dysfunction show a Riggs-electroretinogram (ERG) while patients with a signal transmission defect show a Schubert-Bornschein ERG. The latter group is subdivided into complete or incomplete (ic) CSNB. Only few CSNB cases with Riggs-ERG and only one family with a disease-causing variant in SLC24A1 have been reported. Whole-exome sequencing (WES) in a previously diagnosed icCSNB patient identified a homozygous nonsense variant in SLC24A1. Indeed, re-investigation of the clinical data corrected the diagnosis to Riggs-form of CSNB. Targeted next-generation sequencing (NGS) identified compound heterozygous deletions and a homozygous missense variant in SLC24A1 in two other patients, respectively. ERG abnormalities varied in these three cases but all patients had normal visual acuity, no myopia or nystagmus, unlike in Schubert-Bornschein-type of CSNB. This confirms that SLC24A1 defects lead to CSNB and outlines phenotype/genotype correlations in CSNB subtypes. In case of unclear clinical characteristics, NGS techniques are helpful to clarify the diagnosis.

Thioredoxin rod-derived cone viability factor protects against photooxidative retinal damage

Rod-derived cone viability factor (RdCVF) is a trophic factor of the thioredoxins family that promotes the survival of cone photoreceptors. It is encoded by the nucleoredoxin-like gene 1 Nxnl1 which also encodes by alternative splicing a long form of RdCVF (RdCVFL), a thioredoxin enzyme that interacts with TAU. The known role of thioredoxins in the defense mechanism against oxidative damage led us to examine the retinal phenotype of the Nxnl1(-/-) mice exposed to photooxidative stress. Here we found that, in contrast to wild-type mice, the rod photoreceptors of Nxnl1(-/-) mice are more sensitive to light after exposure to 1700 or 2500 lx. The delivery of RdCVF by AAV to mice deficient of Nxnl1(-/-) protects rod photoreceptors from light damage. Interestingly, the RdCVF2L protein, encoded by the paralog gene Nxnl2, is able to reduce TAU phosphorylation, as does RdCVFL, but does not protect the rod from light damage. Our result shows that the Nxnl1 gene, through the thioredoxin RdCVFL, is part of an endogenous defense mechanism against photooxidative stress that is likely of great importance for human vision.

Holographic laser Doppler imaging of microvascular blood flow

We report on local superficial blood flow monitoring in biological tissue from laser Doppler holographic imaging. In time-averaging recording conditions, holography acts as a narrowband bandpass filter, which, combined with a frequency-shifted reference beam, permits frequency-selective imaging in the radio frequency range. These Doppler images are acquired with an off-axis Mach-Zehnder interferometer. Microvascular hemodynamic components mapping is performed in the cerebral cortex of the mouse and the eye fundus of the rat with near-infrared laser light without any exogenous marker. These measures are made from a basic inverse-method analysis of local first-order optical fluctuation spectra at low radio frequencies, from 0 Hz to 100 kHz. Local quadratic velocity is derived from Doppler broadenings induced by fluid flows, with elementary diffusing wave spectroscopy formalism in backscattering configuration. We demonstrate quadratic mean velocity assessment in the 0.1-10 mm/s range in vitro and imaging of superficial blood perfusion with a spatial resolution of about 10 micrometers in rodent models of cortical and retinal blood flow.

Correlation between aqueous flare and chorioretinal neovascularization in age-related macular degeneration following intravitreal bevacizumab injections

PURPOSE

Prospective evaluation of aqueous flare following intravitreal bevacizumab (Avastin, Genentech Inc., San Francisco, CA, USA) injections in eyes with choroidal neovascularization due to age-related macular degeneration.

PATIENTS AND METHODS

Sixteen eyes of eight patients were recruited. Aqueous humor flare was determined by laser flare meter every month after one intravitreal injection of 1.25mg of bevacizumab at baseline followed by a second injection at month3 (day 100±21days). Four patients received an injection at month6 (±10days), and one patient received an injection at month7.

RESULTS

Two months after the first intravitreal bevacizumab injection, flare values decreased from 10±5.57 (mean±standard deviation) to 5.2±1.69photon count/ms (P=0.0207) and from 8.3±3.59 to 5.4±0photon counts/ms, 2months after the second injection (P=0.02).

CONCLUSION

Significantly decreased aqueous humor flare levels were noted after repeated injections of bevacizumab.

[Intraocular foreign bodies (IOFB) of the posterior segment: retrospective analysis and management of 57 cases]

PURPOSE

To determine the influence of prognostic factors and the type of tamponade agent in surgical management of intraocular foreign bodies (IOFBs) for better visual outcome.

PATIENTS AND METHODS

Fifty-seven consecutive cases were retrospectively reviewed at the XV-XX National Hospital (Paris) between 1 January 2004 and 31 December 2007. Univariate and multivariate analyses were performed to identify prognostic variables. Several parameters were measured: pre- and postoperatively: best corrected visual acuity (BCVA), material and size of the foreign body, entry site, time from trauma to surgical removal, IOFB location, initial retinal detachment, choice of vitreous tamponade agent (none, gas, silicone oil), postoperative visual outcome, and complications (siderosis, endophthalmitis, and vitreoproliferative retinal detachment).

RESULTS

Metal IOFBs accounted for the majority with 80.7% (n=46). The inferior retinal segment was the most frequent location found: 47.4% (n=27). Initial and final mean BCVAs were, respectively, 1.47 (±0.99) and 1.03 (±0.96) (LogMar scale). The mean follow-up was 20.7 months (range, 12-60 months). Initial retinal detachment was found in 24.56% (n=14), with a statically worse prognosis. The BCVA was better in the group with gas tamponade (n=16) than in the group with silicone tamponade (n=21) and the group without a tamponade agent (n=20). Initial BCVA was the most important predictive factor for final BCVA. Time to surgery was a predictive factor of final visual outcome with a cut-off in the first week. The scleral or corneoscleral entry site had a better prognosis than the corneal site. Five cases of siderosis (8.7%) related to delayed management and two cases of endophthalmitis (3.5%) were found (despite use of prophylactic systemic antibiotics). No statistical difference was found regarding the IOFB location on the retina, its size, or the material. Finally, the retina remained detached in nine cases (15.78%). A final BCVA of 20/40 or more was obtained in 39.3 and 17.5% had light perception or worse.

CONCLUSION

The prognosis of an IOFB injury is for the most part uncertain due to a complex combination of parameters. Nevertheless, good postoperative results can be achieved without a silicone tamponade agent. The main prognostic factors related to better visual outcome were initial BCVA, time to surgery (first week), initially attached retina, and the scleral entry site. The main complications were vitreoproliferative retinal detachment, endophthalmitis, and siderosis. The location, type, and size of IOFBs were not statistically significant predictive factors in this study.

Ptf1a/Rbpj complex inhibits ganglion cell fate and drives the specification of all horizontal cell subtypes in the chick retina

During development, progenitor cells of the retina give rise to six principal classes of neurons and the Müller glial cells found within the adult retina. The pancreas transcription factor 1 subunit a (Ptf1a) encodes a basic-helix-loop-helix transcription factor necessary for the specification of horizontal cells and the majority of amacrine cell subtypes in the mouse retina. The Ptf1a-regulated genes and the regulation of Ptf1a activity by transcription cofactors during retinogenesis have been poorly investigated. Using a retrovirus-mediated gene transfer approach, we reported that Ptf1a was sufficient to promote the fates of amacrine and horizontal cells from retinal progenitors and inhibit retinal ganglion cell and photoreceptor differentiation in the chick retina. Both GABAergic H1 and non-GABAergic H3 horizontal cells were induced following the forced expression of Ptf1a. We describe Ptf1a as a strong, negative regulator of Atoh7 expression. Furthermore, the Rbpj-interacting domains of Ptf1a protein were required for its effects on cell fate specification. Together, these data provide a novel insight into the molecular basis of Ptf1a activity on early cell specification in the chick retina.

[Surgery of the idiopathic epimacular membrane on transconjunctival 25-gauge vitrectomy (TSV): a series of 50 cases]

BACKGROUND

The surgery of the idiopathic epimacular membrane has gained from the advent of 25-gauge transconjunctival vitrectomy (TSV) initiated by Fujii in 2002.

PATIENTS AND METHODS

In this retrospective study, we tested 50 patients operated on for epimacular membrane with 25-gauge TSV at the Quinze-Vingts National Ophthalmology Hospital in Paris from December 2004 to June 2006.

RESULTS

No postoperative endophthalmitis, major hypotonia, or sclerotomy leakage were observed. However, two cases (4%) of retinal detachment and 47% postoperative cataract were noted at 3 months. After evolving 3 months later, distant and close visual acuity were significantly improved.

CONCLUSION

TSV appears to be a useful method for epimacular membrane ablation.

Holographic laser Doppler ophthalmoscopy

We report laser Doppler ophthalmoscopic fundus imaging in the rat eye with near-IR heterodyne holography. Sequential sampling of the beat of the reflected radiation against a frequency-shifted optical local oscillator is made onto an array detector. Wide-field maps of fluctuation spectra in the 10 Hz to 25 kHz band exhibit angiographic contrasts in the retinal vascular tree without requirement of an exogenous marker.

The disruption of the rod-derived cone viability gene leads to photoreceptor dysfunction and susceptibility to oxidative stress

Rod-derived cone viability factor (RdCVF) is a thioredoxin-like protein, which has therapeutic potential for rod-cone dystrophies such as retinitis pigmentosa (RP). Cone loss in rodent models of RP is effectively reduced by RdCVF treatment. In this study, we investigate the physiological role of RdCVF in the retina by analyzing the phenotype of the mouse lacking the RdCVF gene, Nxnl1. Although the mice do not show an obvious developmental defect, an age-related reduction of both cone and rod function and a delay in the dark-adaptation of the retina are recorded by electroretinogram (ERG). This functional change is accompanied by a 17% reduction in cone density and a 20% reduction in thickness of the outer nuclear layer. The transcriptome of the retina reveals early changes in the expression of genes involved in programmed cell death, stress-response and redox-signaling, which is followed by a generalized injury response with increased microglial activation, GFAP, FGF2 and lipid peroxidation levels. Furthermore, cones of the mice lacking Nxnl1 are more sensitive to oxidative stress with a reduction of 65% in the cone flicker ERG amplitude measured under hyperoxic conditions. We show here that the RdCVF gene, in addition to therapeutic properties, has an essential role in photoreceptor maintenance and resistance to retinal oxidative stress.

[25-Gauge transconjunctival vitrectomy in a case of bilateral epiretinal membrane associated with a Terson syndrome]

The formation of epiretinal membranes associated with proliferative vitreoretinopathy is known to be a complication of Terson syndrome. We report the first case of a 25-Gauge transconjunctival sutureless vitrectomy performed in one eye as treatment for an epiretinal membrane secondary to a case of Terson syndrome (most probably due to a history of subdural hematoma in childhood). Following a review of the current literature on the subject we report the physiopathologic mechanisms of Terson syndrome and the explanation for the proliferative vitreoretinopathy formation.

[Evolving intravitreous injection technique]

The technique of intravitreous injections has been well documented for several years. Recently, a descriptive article on the intravitreous injections procedure was published in the Journal Français d'Ophtalmologie, and the AFSSAPS (French agency for drug safety) released recommendations concerning this matter on the occasion of commercial launch of pegaptanib. Since that time, the number of intravitreal injections has considerably increased, because anti-VEGF drugs had been made available to ophthalmologists, and several teams have performed a large number of procedures, allowing them to better comprehend intravitreous injections. The present paper describes our current practice of intravitreous injections. Several specialists have exchanged their experiences and issued a common synthesis. Detailed modifications of the initial recommendations have been suggested, with such basic changes such as abandoning preoperative pupil dilatation and easing postsurgical monitoring. Follow-up examinations should be adapted to each patient rather than being systematic. The suggested modifications do not change the procedure of intravitreous injections substantially, but they simplify many steps and detail the various procedures when consensus is lacking.

[Retinopathy of prematurity complicated by late glaucoma: a case report]

INTRODUCTION

We report the case of an acute rise in intraocular pressure occurring decades after the treatment for prematurity (ROP).

CASE REPORT

A 54-year-old preterm woman presented an acute rise in intraocular pressure in her right amblyopic eye. Prominent dilatation of iridal vessels was noted. Fundus was not visible at that time because of corneal edema. Ocular echography was normal. The fellow eye showed temporal attraction of temporal vessels suggestive of retinopathy of prematurity at the cicatricial stage. Neovascular glaucoma was postulated and pressure control was obtained after cyclodestruction and transscleral cryoapplication. After resolution of corneal edema, fundus examination revealed extensive peripheral retinal photocoagulation scars. Iridocorneal angle presented extensive iridocorneal synechias without true new vessels. Visual acuity remained limited to hand motion.

CONCLUSION

Prominent iris dilatation seen in some preterm patients can mimic rubeosis, and, in the present case, mislead to a diagnosis of neovascular glaucoma. Diagnosis can be difficult if the patient is not specifically asked for a history of prematurity. The case underlines the notion that ROP patients may present very late complications of the disease.

[Epiretinal membranes: reasons not to perform vitreoretinal surgery]

Functional results after surgical removal of epiretinal membranes are good; most often, visual acuity improves and the macular syndrome disappears. Transconjunctival vitrectomy to perform peeling of epiretinal membrane has reduced postoperative impairment; however, the surgical complications remain the same. Epiretinal membranes are not uncommon in elderly. The surgical decision is not only based on visual acuity, but many other parameters are also considered. We provide a decision-making algorithm where the elements that suggest foregoing surgery are emphasized.

Injections intra-vitréennes d’anti-VEGF pour la dégénérescence maculaire liée à l’âge exsudative : place des examens complémentaires dans les décisions de retraitement

AIM

Anti-VEGF drugs are the most recent treatments for choroidal neovascularization, the most severe complication of the age-related macular degeneration (AMD). These drugs are administered by intravitreal injections. Several clinical studies have demonstrated their advantages. However, these same studies have not established the modalities for monitoring their efficacy. The aim of this paper is to provide an in-depth look at the existing practices in monitoring anti-VEGF therapy among different French specialists.

METHODS

Several meetings were held with specialists coming from both the hospital setting and private practice to share their practices in monitoring anti-VEGF therapy and to propose more rational monitoring to standardize practices.

RESULTS

The physicians attached an increasing importance to optical coherence tomography (OCT) in monitoring anti-VEGF drugs after intravitreal injection. They acknowledged the value of fluorescein angiography when initiating the treatment and 3 months after beginning anti-VEGF therapy. They advise using fluorescein angiography every time that functional results are not at the level expected by the physician or the patient. The authors provide a flow chart that should help in deciding on retreatment.

CONCLUSION

The authors suggest the use of a flow chart aimed to define indications of retreatment according to clinical response and OCT results.

[Heavy silicone oil as internal tamponade for retinal detachment: efficacy and tolerance]

INTRODUCTION

To evaluate the tolerance and efficacy of heavy silicone oil as internal tamponade for retinal detachment surgery.

PATIENTS AND METHODS

Sixty-six eyes requiring heavy silicone oil for retinal detachment, with at least 1 month follow-up, were retrospectively studied. Preoperative status, surgical technique, tolerance, and anatomical and functional results were analyzed from the patient's file. Indications for heavy silicone injection were inferior retinotomy or inferior retraction in 65% of cases. PVR grade C was present in at least 63% of cases. Retinotomy was performed in 45% of cases. An exchange procedure was performed versus DKline in 65% of cases. Mean follow-up was 7 +/- 4 months.

RESULTS

At the end of follow-up, 59% of eyes had a completely reattached retina, 32% without internal tamponade. Another surgery was necessary in 54% of cases. During follow-up, mean intraocular pressure was normal, and there was a significant intraocular inflammation in three cases (4.5%). In seven cases of the 44 ablations of heavy silicone oil, an adherence of residual bubbles was present. Redetachment occurred after ablation for anatomical success in 41% of cases. BCVA was better than 0.05 (20/400) in 54% of cases at the end of follow-up.

CONCLUSION

Heavy silicone was well tolerated and seems not to be pro-inflammatory in our study. It is a good alternative to standard silicone for inferior retinotomy and inferior breaks without PVR. It is not a treatment of inferior retraction, and is not a long-term internal tamponade. During the ablation of heavy silicone oil, adherence of residual bubbles is possible, in which case a coaxial light or an endoillumination could be needed during ablation.

Familial central retinal vein occlusion

AIM

To report four cases of central retinal vein occlusion (CRVO) in a French family.

PATIENTS AND METHODS

Ophthalmological examination and medical work-up of seven members of the family.

RESULTS

There were four cases of CRVO in two consecutive generations. Three of them had CRVO in both eyes. Arterial hypertension was present in two, associated to glaucoma in one. Medical work-up did not reveal additional risk factors.

CONCLUSIONS

We report a case of familial clustering of CRVO. Our cases combined to other cases reported in the literature provide arguments for the existence in some subjects of a genetic predisposition of CRVO. Additional case series are however needed to confirm this hypothesis.

Cellules souches rétiniennes : mécanisme de différenciation et potentiel thérapeutique

Retinal dystrophies are rarely curable diseases and several avenues of research are being pursued, such replacement therapies and pharmacological treatment. Among them, the transplantation of functional retinal cells has been envisaged in order to restore vision in patients who have these diseases by repopulating the damaged retina and/or by rescuing retinal neurons from further degeneration. Over the past few years, identification and characterization of stem cells has opened new avenues in cell-replacement therapy. Since retinal stem cells are already present during embryonic development, they persist in the adult mammalian eye only in the ciliary marginal zone, even a stem cell potential has been described for the Müller glia in the retina. This result opened possibilities of regeneration by mobilizing endogenous stem cells to respond to injury. Regarding the transplantation studies, in all experiments using different types of stem cells (retinal progenitors, neural stem cells, bone marrow-derived stem cells and ES cells), despite their incorporation within the host's retina, the transplanted cells failed to express retina-specific markers and to establish synaptic connections. Therefore, the true potential of the different stem cells in retina repair can only be realized with more information about mechanisms that regulate their proliferation and differentiation; and by development of techniques that allow their prospective identification and enrichment.

Advanced glycation end products can induce glial reaction and neuronal degeneration in retinal explants

BACKGROUND/AIMS

Neuronal degeneration has been reported to occur in diabetic retinopathy before the onset of detectable microvascular abnormalities. To investigate whether advanced glycation end products (AGE) could be directly responsible for retinal neurodegeneration, retinal explants were incubated with glycated bovine serum albumin (BSA).

METHODS

Retinal explants obtained from non-diabetic adult rats were incubated 4 days with or without 200 mug/ml glycated BSA. Neural apoptosis was quantified by terminal dUTP nick end labelling (TUNEL) binding and immunostaining with anti-cleaved caspase-3 antibody. Expression of glial fibrillary acidic protein (GFAP) was localised by immunofluorescence.

RESULTS

TUNEL and cleaved caspase-3 positive cells increased significantly by 2.2-fold and 2.5-fold in retinal explants incubated in glycated BSA (p<0.05), respectively. The ganglion cell layer was the most sensitive retinal layer to the glycated BSA. Neuronal degeneration was confirmed by the increased GFAP labelling in Müller glial cells from retinal explants treated with glycated BSA.

CONCLUSION

These results suggest that AGE could induce retinal neurodegeneration in the absence of blood perfusion. Cells in the ganglion cell layer appeared to be the most sensitive as in diabetic retinopathy and its animal models. AGE toxicity could therefore contribute to the early pathological mechanisms of diabetic retinopathy.

Das „European Vision Institute“

The European Vision Institute EEIG (EVI) creates a new legal entity based on Community law to facilitate and encourage cross-border co-operation in vision research. Its major objectives are to conduct and support research, training, health information dissemination and other programmes with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight and the special health problems and requirements of the blind and visually disabled. EVI aims to foster centres in the EU in capacity building for innovative projects, to increase the flexibility, attractiveness and competitiveness of research careers, especially for young researchers. In addition, EVI will serve to co-ordinate activities with patient organisations and to build a pan-European platform for clinical trials.

Glycine receptors in a population of adult mammalian cones

Glycinergic interplexiform cells provide a feedback signal from the inner retina to the outer retina. To determine if cones receive such a signal, glycine was applied on cultured porcine cone photoreceptors recorded with the patch clamp technique. A minor population of cone photoreceptors was found to generate large currents in response to puff application of glycine. These currents reversed close to the calculated equilibrium potential for chloride ions. These glycine-elicited currents were sensitive to strychnine but not to picrotoxin consistent with the expression of alpha-beta-heteromeric glycine receptors. Glycine receptors were also activated by taurine and beta-alanine. The glycine receptor antibody mAb4a labelled a minority of the cone photoreceptors identified by an antibody specific for cone arrestin. Finally, expression of the beta subunit of the glycine receptor was demonstrated by single cell RT-PCR in a similar proportion (approximately 13%) of cone photoreceptors freshly isolated by lectin-panning. The identity of cone photoreceptors was assessed by their specific expression of the cone arrestin mRNA. The population of cone photoreceptors expressing the glycine receptor was not correlated to a specific colour-sensitive subtype as demonstrated by single cell RT-PCR experiments using primers for S opsin, cone arrestin and glycine receptor beta subunit. This glycine receptor expression in a minority of cones defines a new cone population suggesting an unexpected role for glycine in the visual information processing in the outer retina.

Description des pratiques pour la réalisation des injections intravitréennes

Drugs to treat retinal diseases are often injected intravitreally. This procedure can cause severe complications. We present ways to minimize the risk for complications. Rigorous preoperative antisepsis with povidone iodine, a sterile environment (using gloves and a mask for the injector, a lid speculum, and a drape on the eye to be injected), and immediate follow-up after injection are key issues of the injection technique.

Évaluation clinique de 5FU-héparine dans la prévention de la prolifération vitréorétinienne

PURPOSE

To study the safety and efficacy of adjuvant combination therapy using 5-fluorouracil and heparin for prevention of proliferative vitreoretinopathy (PVR) during vitrectomy for retinal detachment surgery.

METHODS

Two consecutive groups of 30 eyes with a rhegmatogenous retinal detachment (grade C1 or more) were prospectively compared. In the study group, 5-FU and heparin were administrated in the intraoperative infusion. Clinical safety and the efficacy were regularly studied over 1 year.

RESULTS

In the 5-FU heparin therapy group, keratitis was more frequently observed the 1st day after surgery (p = 0.005), but not after 1 week (p = 0.54). However, conjunctival hyperemia was more severe after 1 and 7 days (p = 0.04). In both groups, no differences were found concerning intraocular pressure, postoperative hemorrhage or inflammatory reaction (flare) of the anterior chamber and the aspect of the eyelids (p > or = 0.14). The number of reoperations resulting from PVR, after 1 month and 1 year, was not significantly different between the two groups (p > or = 0.3). The reattachment rate and visual acuity (BSCVA) were not statistically different after 1 year (p > or = 0.12).

CONCLUSION

Adjuvant combination therapy using 5-FU and heparin seems to be safe. However, its efficacy needs to be demonstrated by larger studies including eyes presenting a lower grade of PVR (grade B).

[Pharmacological adjuvants for surgical treatment of proliferative vitreoretinopathy]

Proliferative vitreoretinopathy (PVR) is the major cause of retinal detachment surgery failure. Many adjuvants were studied in vitro and on animals, some were studied on humans. Daunomycin seems to reduce PVR recidivism. 5-FU and steroids are nontoxic but their efficacy is not clear. Heparin reduced postoperative inflammation and seems to reduce PVR recidivism when associated with 5-FU. Associating heparin and steroids seems to reduce PVR in some groups of patients (aphakic, anterior PVR). Colchicine and retinoic acid per os are ineffective, silicone oil is effective as an internal tamponade but not as an adjuvant of PVR. Currently, no molecule has proven efficacy as an adjunctive treatment of PVR.

GOAnno: GO annotation based on multiple alignment

GOAnno is a web tool that automatically annotates proteins according to the Gene Ontology (GO) using evolutionary information available in hierarchized multiple alignments. GO terms present in the aligned functional subfamily can be cross-validated and propagated to obtain highly reliable predicted GO annotation based on the GOAnno algorithm.

AVAILABILITY

The web tool and a reduced version for local installation are freely available at http://igbmc.u-strasbg.fr/GOAnno/GOAnno.html

SUPPLEMENTARY INFORMATION

The website supplies a detailed explanation and illustration of the algorithm at http://igbmc.u-strasbg.fr/GOAnno/GOAnnoHelp.html.

DNA repair in the degenerating mouse retina

In light of different recent results suggesting that the adult mammalian central nervous system can produce new neurons, possibly as an endogenous repair mechanism, we investigated whether neurogenesis occurs in response to photoreceptor degeneration in the rd1 mouse, a model of human-inherited retinal dystrophy. Bromodeoxy-Uridine (BrdU) incorporation and proliferating cell nuclear antigen (PCNA) expression experiments detected cell proliferation in the extreme peripheral retina, in both wt and rd1 retina, independent of degeneration. BrdU incorporation and PCNA expression also occurred in rd1 photoreceptors. Our results strongly suggest that these photoreceptors undergo DNA repair: p53, PCNA, and DNA ligase IV are expressed before photoreceptor death, consistent with a model where photoreceptors expressing the rd1 mutation activate a process of DNA repair but which is overwhelmed by the disease mutation leading to apoptotic death. The existence of such a balance offers potential new targets for neuroprotective approaches.

Pathologies rétiniennes d’origine héréditaire et DMLA : nouvelles perspectives thérapeutiques

This article summarizes our current knowledge on two types of retinal diseases: hereditary retinal degeneration and wet aged-related macular degeneration. Our understanding of retinal physiopathology in hereditary retinal degeneration and the successful experimental therapeutic results on animal models call for a new approach to these patients to prepare future clinical trials. Longitudinal follow-up of the functional alteration rhythm based on international standards and by expert centers is an essential prerequisite to including these patients in future clinical trials. Creating international databases that include data on follow-up using electrophysiological, psychophysical and morphological analyses would require standards defining how each of these procedures should be carried out. Furthermore, the relevance and value of the various examinations would then be evaluated in a longitudinal manner. The repeated use of these procedures in the various centers would bring to light any limitations these techniques may have for use in prospective studies. Continuous re-evaluation of these investigative techniques will therefore be necessary, a crucial factor in the preparation of multicenter clinical studies. The inclusion of patients phenotyped at different centers would require that certification procedures be set up for these centers. A great leap forward, clinical trials on new antiangiogenic approaches for the treatment of neovascular AMD are currently underway. The reasons for the switch between the neovascular and atrophic forms of AMD are as yet unknown, but these new approaches are based on the events that occur sequentially during the angiogenic response.

[Dacryolithiasis: diagnosis using nasal endoscopy]

PURPOSE

The purpose of this study was to assess the value of two new clinical findings for the diagnosis of dacryolithiasis discovered with nasal endoscopy: anatomical abnormalities of the Hasner valve (HV) and mucopurulent discharge visible at this valve. The value of these findings is compared with other clinical and radiological signs of dacryolithiasis. A hypothesis is developed as to the responsibility of the HV in the formation of dacryolithiasis.

METHOD

This study was prospective and based on 797 operations performed for epiphora: 647 endonasal dacryocystorhinostomies and 150 meatotomies of the HV, with systematic preoperative nasal videoendoscopy. Ninety dacryocystographies (DCGs) and 129 lacrimal computed tomographies (LCT) were preoperatively performed.

RESULTS

Dacryoliths were found in 55 of 797 patients (6.9%). The HV could be examined in 48 patients in the lithiasis group and in 687 patients in the control group. Mucopurulent discharge was observed in 22 patients with lithiasis (45.8%) and in 40 patients (5.8%) (p<10(-6)) of the control group. Anatomical abnormalities of the HV were found in 40 patients with dacryolithiasis (83.3%) as compared to 82 patients ing the control group (11.4%) (p<10(-6)). In 13 patients, the VH was very small (<2 mm), in 12 patients it was very long (>15 mm), and in 15 patients both abnormalities were observed. Other clinical signs were young age (mean, 48.2 years vs 59.1% in the control group) (p<0.05), a history of acute noninfectious dacryocystic retention (38.2% vs 9.5%) (p<10(-5)), partial obstruction of the lacrimal pathway (LP) (61.8% vs 30.5%) (p<10(-5)). The 28 LCTs that were performed in subjects who had lithiasis made it possible to diagnose 19 cases of dacryolithiasis and confirmed abnormalities of the HV causing narrowing of the LP in 20.

CONCLUSION

Dacryolithiasis is frequent and often misdiagnosed. When dacryolithiasis is suspected, a nasal videoendoscopic exam must be done to seek HV abnormalities and mucopurulent discharge at this valve. This latter finding, i.e., the association of mucopurulent discharge with a patent lacrimal system, has high specificity. The finding of numerous anatomical abnormalities of the HV may be an indication that congenital malformation of the HV is the cause of many cases of lithiasis.

Hypoglycemia induces general neuronal death, whereas hypoxia and glutamate transport blockade lead to selective retinal ganglion cell death in vitro

PURPOSE

To examine the impact of experimental ischemia and interruption of glutamate transport on retinal neuronal cell, especially retinal ganglion cell (RGC), survival in vitro.

METHODS

Cell cultures were prepared from adult pig retinas and maintained under different experimental conditions of increasing hypoglycemia, environmental hypoxia (delayed postmortem period or atmospheric PO2 <2%), or chemical hypoxia (potassium cyanide), or in the presence of glutamate transporter blockers L-trans-pyrrolidine-2,4-dicarboxylic acid (tPDC) and L(-)-threo-3-hydroxyaspartic acid (THA), or the glutamine synthetase inhibitor methionine sulfoximine (MS). After 48 hours, cells were returned to standard culture conditions and allowed to develop for 5 days, when they were fixed and immunostained with different retinal neuronal phenotypic markers.

RESULTS

Control normoxic cultures contained large numbers of immunocytochemically identified photoreceptors (PRs), bipolar cells (BCs), amacrine cells (ACs), and RGCs after 7 days in vitro. A 24-hour postmortem delay before culture led to significant reductions in all types (40%-70%), proportionately greater in ACs and RGCs. Lowering of sugar levels also led to increased losses in all cell types, whereas potassium cyanide treatment deleteriously affected only ACs and RGCs. Ambient hypoxia led to consistent reductions only in the number of RGCs, which were exacerbated by addition of high concentrations of glutamate. Inclusion of glutamate receptor antagonists had a partial protective effect against RGC loss. Treatment with tPDC and THA also led to selective RGC death, but MS had no effect on any cells.

CONCLUSIONS

Different components of the ischemic pathologic process (hypoxia, hypoglycemia, glutamate transport failure) lead to distinctly different patterns of neuronal loss in adult retina in vitro. RGCs are especially vulnerable, corresponding to their in vivo susceptibility. These data may suggest neuroprotective strategies for limiting retinal damage during ischemia.

Rod-cone interactions: developmental and clinical significance

During the last decade, numerous research reports have considerably improved our knowledge about the physiopathology of retinal degenerations. Three non-mutually exclusive general areas dealing with therapeutic approaches have been proposed; gene therapy, pharmacology and retinal transplantations. The first approach involving correction of the initial mutation, will need a great deal of time and further development before becoming a therapeutic tool in human clinical practice. The observation that cone photoreceptors, even those seemingly unaffected by any described anomaly, die secondarily to rod disappearance related to mutations expressed specifically in the latter, led us to study the interactions between these two photoreceptor populations to search for possible causal links between rod degeneration and cone death. These in vivo and in vitro studies suggest that paracrine interactions between both cell types exist and that rods are necessary for continued cone survival. Since the role of cones in visual perception is essential, pending the identification of the factors mediating these interactions underway, rod replacement by transplantation and/or neuroprotection by trophic factors or alternative pharmacological means appear as promising approaches for limiting secondary cone loss in currently untreatable blinding conditions.

Expanded polyglutamines induce neurodegeneration and trans-neuronal alterations in cerebellum and retina of SCA7 transgenic mice

Among the eight progressive neurodegenerative diseases caused by polyglutamine expansions, spinocerebellar ataxia type 7 (SCA7) is the only one to display degeneration in both brain and retina. We show here that mice overexpressing full-length mutant ataxin-7[Q90] either in Purkinje cells or in rod photoreceptors have deficiencies in motor coordination and vision, respectively. In both models, although with different time courses, an N-terminal fragment of mutant ataxin-7 accumulates into ubiquitinated nuclear inclusions that recruit a distinct set of chaperone/proteasome subunits. A severe degeneration is caused by overexpression of ataxin-7[Q90] in rods, whereas a similar overexpression of normal ataxin-7[Q10] has no obvious effect. The degenerative process is not limited to photoreceptors, showing secondary alterations of post-synaptic neurons. These findings suggest that proteolytic cleavage of mutant ataxin-7 and trans-neuronal responses are implicated in the pathogenesis of SCA7.

Selective transplantation of rods delays cone loss in a retinitis pigmentosa model

BACKGROUND

Rod-cone retinal degenerations (retinitis pigmentosa) are typified by initial rod loss followed by secondary cone death. Rod death, predominantly caused by gene mutations expressed specifically in these cells, induces scotopic vision loss. Cone death, the overriding cause of blindness, has no current explanation. Disease progression and preliminary data suggest that cone survival depends on rods.

OBJECTIVE

To establish whether rod transplantation into mutant rodless retinas could halt cone loss.

METHODS

We transplanted pure sheets of rods isolated from normal-sighted mice into the subretinal space of recipient retinal degeneration mice lacking rods but possessing approximately 30% residual cones. Control animals were unoperated on or grafted with inner retinal cells from young normal donors, entire retinas from aged retinal degeneration mice, or gelatin. Two weeks after surgery, we quantified by an unbiased method the numbers of host retinal cones after immunolabeling with specific markers.

RESULTS

Only mice receiving rod-rich transplants demonstrated statistically significant greater cone numbers, with rescue of 40% of host cones normally destined to die during this period.

CONCLUSION

Cone survival depends specifically on rods.

CLINICAL RELEVANCE

Such findings indicate that transplantation of rods could limit loss of cones, thus preserving useful vision in human retinitis pigmentosa. Arch Ophthalmol. 2000;118:807-811

Retinitis pigmentosa: rod photoreceptor rescue by a calcium-channel blocker in the rd mouse

Retinitis pigmentosa is an inherited degenerative disease of photoreceptors leading to blindness. A well-characterized model for this disease is provided by the retinal degeneration mouse, in which the gene for the rod cGMP phosphodiesterase is mutated, as in some affected human families. We report that D-cis-diltiazem, a calcium-channel blocker that also acts at light-sensitive cGMP-gated channels, rescued photoreceptors and preserved visual function in the retinal degeneration mouse. The long record of diltiazem prescription in cardiology should facilitate the design of clinical trials for some forms of retinitis pigmentosa.

Normal retina releases a diffusible factor stimulating cone survival in the retinal degeneration mouse

The role of cellular interactions in the mechanism of secondary cone photoreceptor degeneration in inherited retinal degenerations in which the mutation specifically affects rod photoreceptors was studied. We developed an organ culture model of whole retinas from 5-week-old mice carrying the retinal degeneration mutation, which at this age contain few remaining rods and numerous surviving cones cocultured with primary cultures of mixed cells from postnatal day 8 normal-sighted mice (C57BL/6) retinas or retinal explants from normal (C57BL/6) or dystrophic (C3H/He) 5-week-old mice. After 7 days, the numbers of residual cone photoreceptors were quantified after specific peanut lectin or anti-arrestin antibody labeling by using an unbiased stereological approach. Examination of organ cultured retinas revealed significantly greater numbers of surviving cones (15-20%) if cultured in the presence of retinas containing normal rods as compared with controls or cocultures with rod-deprived retinas. These data indicate the existence of a diffusible trophic factor released from retinas containing rod cells and acting on retinas in which only cones are present. Because cones are responsible for high acuity and color vision, such data could have important implications not only for eventual therapeutic approaches to human retinal degenerations but also to define interactions between retinal photoreceptor types.

Intravitreal injection of ganglioside GM1 after ischemia reduces retinal damage in rats

BACKGROUND AND PURPOSE

Gangliosides are normal components of cell membranes and contribute to structural rigidity and membrane function. They have been shown to protect against various insults in the brain. We have shown previously that GM1 administered intraperitoneally before the induction of retinal ischemia provides a protective effect. This study evaluates the protective effect of GM1 administered intravitreally after ischemia on retinal lesions.

METHODS

We induced retinal ischemia unilaterally in Long-Evans rats by increasing intraocular pressure to 160 mm Hg for 60 minutes. GM1 (20 microL x 10(-5) mol/L) or saline (20 microL) was injected into the vitreous 15 minutes after ischemia, and the postischemic survival time was either 8 or 15 days. The degree of retinal damage was assessed by histopathological study.

RESULTS

Retinal ischemia led to reductions in thickness and cell number, principally in the inner retinal layers (39% to 80%) and to a lesser extent in the outer retinal layers (26% to 45%). Postischemic treatment with intravitreally injected GM1 conferred significant protection against retinal ischemic damage after both 8 and 15 days of survival time. After 8 days of reperfusion, the ischemia-induced loss in overall retinal thickness was reduced by 15% and those of the inner nuclear and plexiform layers by 44% and 17%, respectively. Ischemic-induced ganglion cell and inner nuclear cell density losses were reduced by 37% and 27%, respectively. After 15 days of reperfusion, approximately the same statistically significant differences could be observed in comparison with the 15-day saline-injected group.

CONCLUSIONS

GM1 protects the rat retina from pressure-induced ischemic injury when given intravitreally after the insult. The protection provided by GM1 after initiation of retinal damage could be of therapeutic interest.

[Retinal grafts: biological problems and clinical stakes]

Retinal transplantation, formerly perceived as unrealistic, has become over the past decade a major clinical and biological undertaking in several laboratories and eye clinics. We describe the insights gained through the pioneering experimental works of Del Cerro et al, Turner et al, Gouras et al, Aramant et al, Lund et al e.g. the survival of transplants, the lack of immune response to photoreceptors, their integration and expression of neuronal markers, but also the dysplastic arrangement into rosettes and the lack of a definitive proof for functionality. Our laboratory has undertaken to establish the trophic and synaptic functions of sheets of photoreceptors transplanted, as described by Silverman et al, in the subretinal space of mutant rd mice carrying a retinal degeneration similar to human retinitis pigmentosa. Clinical applications to this condition as well as in cases of end-stage age related macular degeneration are discussed.