Black patients sustain vision loss while White and South Asian patients gain vision following delamination or segmentation surgery for tractional complications associated with proliferative diabetic retinopathy

PurposeThis retrospective comparative case series aims to determine whether patient ethnicity (White versus South Asian versus Black) is related to the outcome of surgical treatment for traction complications of severe proliferative diabetic retinopathy (PDR).SettingMoorfields Eye Hospital London, UK.MethodsAll patients who underwent vitrectomy with, delamination and/or segmentation for PDR over a 5-year period (2009-2014) were reviewed retrospectively. Patients were divided into White, South Asian or Black groups, and their age, gender, HbA1C and type of diabetes were recorded. A total of 484 patients (253 White, 117 South Asian, 114 Black) were included. Twenty-one patients were excluded due to inadequate documentation.OutcomesLogMAR Visual acuity (converted from Snellen) (VA), was recorded pre-operatively and ~6 months post surgery (range 5-8 months). Surgical outcome was classified according to the type and duration of tamponade required post-operatively.ResultsPre-operative VA and HbA1C values were similar across all three ethnic groups (P=0.64 and 0.569, respectively). Change in VA (mean±SD) was 0.41±0.78, 0.14±0.76 and -0.26±0.57 in White, South Asian and Black patient groups respectively (P<0.001). Multiple regression analysis showed that post-op VA was significantly related to race and pre-op VA only (both P<0.001). The Black patient group were more likely to require silicone oil tamponade (P<0.001) and long-term retention of silicone oil (P<0.001) than the White and South Asian patient groups.ConclusionsThis study demonstrates that Black patients on average lose vision following delamination surgery for traction complications of PDR while White and South Asian patients gain vision. The same group is also at higher risk of retaining silicone more than 6 months after surgery. This difference remains even when corrected for glycaemic control. The higher risk of visual loss and long-term retention of silicone oil in black patients requires further investigation. If these results are confirmed, surgeons should consider their patients' ethnicity before proceeding with surgical treatment of diabetic tractional detachment.

A review and update on the current status of stem cell therapy and the retina

INTRODUCTION OR BACKGROUND

Many diseases of the retina result in irreversible visual loss. Stem cell (SC) therapy is a rapidly developing field and represents a novel approach to replace non-functioning neuro-retinal cells.

SOURCES OF DATA

A systematic computerized literature search was conducted on PubMed (http://www.ncbi.nlm.nih.gov/pubmed/).

AREAS OF AGREEMENT

The use of stem cells (SCs) in animal models of retinal diseases has resulted in improvement in visual function and performance. SC therapy represents an exciting prospect in restoring vision. Areas of controversy The use of human embryonic SCs raises ethical concerns.

GROWING POINTS

Human trials using SCs in retinal diseases have recently been approved.

AREAS TIMELY FOR DEVELOPING RESEARCH

The success of SCs in retinal therapy depends not only on implanted cell survival, but also on how well SCs migrate, integrate and form synapses. Further research will be needed to overcome these hurdles.

Dynamics of phosphorothioate oligonucleotides in normal and laser photocoagulated retina

AIMS

To investigate the distribution, persistence, and stability of fluorescently labelled phosphorothioate oligonucleotides (PS-ODNs) in normal and laser photocoagulated retina following intravitreal injection in the rat.

METHODS

Fluorescently labelled PS-ODNs were injected intravitreally into pigmented eyes at doses of 0.5-10.0 nmol in 2.0 microl solution. The dynamics of PS-ODNs was evaluated by fluorescent microscopy of cryosections and flat mounted retinal pigment epithelium (RPE)-choroid-sclera. Genescan analysis was used to assess the integrity of PS-ODNs in the retina after injection. The dynamics of PS-ODNs was also evaluated in the retina following krypton laser photocoagulation with a protocol producing choroidal neovascularisation (CNV).

RESULTS

Following intravitreal injection the PS-ODNs demonstrated dose and time dependent distribution and persistence in the retina, where they accessed all neural layers. However, they preferentially accumulated in the RPE layer, demonstrated as bright granules in the cytoplasm of the cells. Injections of 5.0 and 7.5 nmol of PS-ODNs exhibited strong fluorescence in the retina for 6 weeks after injection. Genescan analysis demonstrated that the PS-ODNs remained almost completely intact for at least 12 weeks. Following laser treatment, the PS-ODNs were concentrated in the regions of laser photocoagulation and retained high intensity for at least 8 weeks after injection, particularly localised to macrophages, RPE, and the local choroidal tissue.

CONCLUSIONS

These results indicate that PS-ODNs are stable and accessible to most neural layers of the retina, and they preferentially accumulate in the RPE layer following intravitreal injection. The successful delivery of PS-ODNs into normal and laser photocoagulated retina suggests that PS-ODNs may have potential in the development of therapy for attenuating retinal degenerations and CNV.

Cell polarity, phagocytosis and viral gene transfer in cultured human retinal pigment epithelial cells

PURPOSE

To investigate whether there is a difference in the expression of adenovirus transgenes in human retinal pigment epithelial cells when the vector was exposed to the apical or basal surface, the effect of transgene expression on rod outer segment (ROS) phagocytosis and finally, the role of phagocytosis in gene transfer to RPE cells, using the Royal College of Surgeons (RCS) rat.

METHODS

Monolayers of human retinal pigment epithelium (HRPE) or an RPE cell line (A407) had the apical or basal surfaces exposed to 10(7) pfu/ml of replication deficient adenovirus (Ad.RSV.betagal) carrying the beta-galactosidase marker gene, and the numbers of expressing cells were compared. Parallel cultures were infected and challenged with fluorescein-labelled bovine rod outer segments (FBROS). The fluorescence of infected versus uninfected cells was recorded for both challenged and unchallenged states, using fluorophotometric flow cytometry. Primary cultures of RCS rat RPE were established and the transgene uptake dynamics compared to control Long Evans rat RPE cells.

RESULTS

The expression of transgene in HRPE and A407 cell cultures was an order of magnitude greater when the vector was exposed apically (analysis of variance p < 0.05). There was no difference in the phagocytic capacity of Ad.RSV.betagal-infected and -noninfected cells when challenged with FBROS. There was also no difference in the number of cells expressing transgene, when compared to the RCS or Long Evans control rat RPE.

CONCLUSIONS

The surface of exposure in polarized retinal pigment epithelial cells affects the rate of uptake and expression of adenovirus. The defective ROS phagocytosis in RCS rat RPE cells did not lead to a decrease in transgene expression relative to the Long Evans control cells. Finally we have found that phagocytosis is not significantly altered with adenoviral transgene expression in this in vitro model.

Quantification of P-selectin expression after renal ischemia and reperfusion

Neutrophils are important in ischemia and reperfusion injury. Multiple factors may be responsible for the adhesion of granulocytes to endothelial cells. P-selectin is a carbohydrate-binding glycoprotein that is stored preformed in endothelial cells as Weibel-Palade bodies. This preformation implies a very early role of P-selectin in the leukocyte adhesion process. Previous studies of P-selectin have not quantified its expression. The purpose of this study is to quantitate the expression and time course of P-selectin in response to renal ischemia and reperfusion injury. P-selectin was measured in 34 C57BL-6 mice after 30 minutes of occlusive left renal ischemia followed by 20 minutes, 2, 5, 10, and 24 hours of reperfusion. This was also performed in control and sham laparotomy groups. P-selectin was quantified using a new double radiolabeled 125I/131I monoclonal antibody technique and reported as percent injected dose per gram of tissue. P-selectin expression peaked at 20 minutes, plateaued up to 5 hours, and fell at 10 hours. Additionally, genetically altered mice that do not express P-selectin showed no up regulation after 5 hours of reperfusion. Pathology results confirmed significant renal injury. Renal ischemia and reperfusion injury caused significant upregulation of P-selectin. Expression of P-selectin at the short reperfusion time of 20 minutes reinforces the premise that P-selectin is one of the earliest adhesion molecules expressed. This early peak is probably caused by the release of preformed P-selectin. The delineation of these mechanisms of injury may be important in understanding and preventing renal injury in transplantation, sepsis, and shock.

Ocular gene therapy: the basic science and current state of research

Recent technical advances have led to the demonstration of the molecular basis of many genetic eye diseases. Methods now in use have been able to both suppress and insert genes in vitro and in vivo in ocular cells. The combination of this new knowledge and these techniques offers the potential for a new therapeutic approach to diseases that currently have no treatments. The scientific basis of gene therapy is introduced and then the current state of research is discussed in relation to the eye and ocular tissues.

Dynamics of gene transfer to retinal pigment epithelium

PURPOSE

To examine the nature and dynamics of gene transfer to human retinal pigment epithelium (RPE) using an adenoviral vector and adjuvants that may enhance the uptake of recombinant adenoviruses.

METHODS

Human RPE cultures (HRPE7) were transfected in vitro with varying concentrations (4, 20, 40, 120, and 200 pfu/microliter) and for varying periods (1, 2, 4, 16, 24, 48, and 72 hours) with a replication-deficient adenovirus (Ad.RSV. beta gal) containing the bacterial beta-galactosidase transgene (beta gal). The expression of beta gal was monitored by counting after X gal staining. The transgene expression profiles were compared to those of human F2000 fibroblasts under the same conditions. The adjuvant effect of sodium hyaluronate (HA) on the expression of beta gal was tested in F2000 and early and late passage human RPE cells for differing concentrations of HA, viral titers, and incubation times. Immunofluorescent cytochemistry was carried on HRPE7 and F2000 cells for the HA receptors, homing receptor CD44 (CD44), intercellular adhesion molecule 1 (ICAM-1), and the receptor for hyaluronan mediated motility (RHAMM).

RESULTS

The number of HRPE7 and F2000 cells expressing the adenoviral transgene increased consistently with increasing incubation time and viral titer. There was a higher uptake of Ad.RSV. beta gal in HRPE7 cells compared to the F2000 fibroblasts under the same conditions. There was an increase of 28.1% and 41.4% in the number of RPE7 cells expressing adenoviral transgene and 16.2% and 15.8% F2000 fibroblast cells expressing the adenoviral transgene in the presence of 0.001% and 0.005% HA, respectively. Significant adjuvant effects on transgene expression also were shown in HRPE51 cells. It appears that the effects of increasing viral titer, length of incubation, and the presence of HA on transgene expression are at least additive. The appearance of CD44 and ICAM receptors on RPE7 and F2000 cells and RHAMM receptors on F2000 cells was similar. The RHAMM receptors in HRPE7 cells, however, were shown preferentially over the nucleus.

CONCLUSIONS

On the basis of these results, the authors propose that adenovirus transgene expression increases with increasing incubation time and viral titer in cell culture. The rate of increase of expression differs between human RPE cells and the F2000 fibroblast cells, which may offer a targeting opportunity. The authors propose that the use of HA can offer both an adjuvant effect and a targeting advantage in terms of transferring adenoviral transgenes to human RPE in culture.

Multiple vortex vein varices masquerading as choroidal secondaries

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Use of lasers in vascular disease discussed at International Congress

In general, most of the physicians at the International Congress III, whether they were vascular surgeons, cardiologists, or radiologists, agreed that lasers have their place in vascular medicine. They did acknowledge, however, that further refinements are required in the lasers themselves and in assessment techniques for vascular interventions of any type. Such technological advancements will demand continued changes in nurses' knowledge and skills.

Ambulatory surgery--the next decade

Most of the experts agree: new technology, new laser applications, and new concepts of health care will keep the ambulatory surgery industry moving and growing. Statistics from the past seem to imply the same thing. Ten years from now we can reread this article and see if we were accurate.