Different lasers and techniques for proliferative diabetic retinopathy

Targeting pericyte retention in Diabetic Retinopathy: a review

Diabetic retinopathy is a common yet severe complication of diabetes mellitus and is the leading cause of blindness in middle-aged adults. After years of poorly managed hyperglycemia, complications begin as non-proliferative diabetic retinopathy but can then progress into the proliferative stage marked by neovascularization of the retina. Multiple pathologic mechanisms caused by chronic hyperglycemia damage the retinal vasculature leading to pericyte drop out and the progression of the disease. This review outlines the major pathways of pathogenesis in diabetic retinopathy, highlighting the protective role pericytes play in preserving the blood-retinal barrier. Given the loss of this cell line is a defining feature of the disease, ways in which to prevent pericyte dropout within retinal vasculature is discussed, targeting various pathogenesis pathways of diabetic retinopathy.

Peripheral PRP in the Operating Room vs Standard Clinic PRP for the Initial Treatment of PDR

Purpose: To compare the long-term outcomes of standard panretinal photocoagulation (PRP) performed in the operating room (OR) with peripheral PRP performed in the clinic in treatment-naïve patients with proliferative diabetic retinopathy (PDR). Methods: Consecutive cases from 2017 to 2022 were retrospectively reviewed. Exclusion criteria included previous PRP, pars plana vitrectomy performed at the time of the initial PRP, PRP performed in another setting within 3 months of the initial treatment, a documented plan for future PRP at the time of the initial treatment, and less than 3 years of follow-up. Negative binomial regressions were used to compare the number of subsequent interventions between the 2 groups and t tests to compare the visual acuity (VA) outcomes. Results: Of the 961 eyes of 679 patients screened, 82 eyes of 53 patients met the inclusion criteria. The initial PRP was performed in the OR (OR cohort) in 57 eyes of 38 patients and in the clinic (clinic cohort) in 25 eyes of 15 patients. The OR cohort had a mean of 0.4 subsequent surgeries and 0.8 subsequent PRP treatments and the clinic cohort, 0.8 subsequent surgeries (P < .05) and 1.8 subsequent PRP treatments (P < .05). No significant between-group difference was found in the VA outcomes over the long-term follow-up (mean, 44.2 months). Conclusions: Peripheral PRP performed in the OR resulted in fewer subsequent interventions than standard PRP in the clinic and may afford better control of PDR.

Mesenchymal Stem Cells Regulate Microglial Polarization via Inhibition of the HMGB1/TLR4 Signaling Pathway in Diabetic Retinopathy

Diabetic retinopathy (DR) is recognized as the most prevalent retinal degenerative disorder. Inflammatory response usually precedes microvascular alteration and is the primary factor of diabetic retinopathy. Activated microglia express many pro-inflammatory cytokines that exacerbate retina inflammation and disruption. In the present study, we found that MSCs alleviated blood-retina barrier (BRB) breakdown in diabetic rats, as evidenced by reduced retinal edema, decreased vascular leakage, and increased occludin expression. The MSC-treated retinal microglia exhibited reduced expression of M1-phenotype markers in the diabetic rats, including inducible nitric oxide synthase (iNOS), CD16, and pro-inflammatory cytokines. On the other hand, MSCs increased the expression of M2-phenotype markers, such as arginase-1 (Arg-1), CD206, and anti-inflammatory cytokines. HMGB1/TLR4 signaling pathway is activated in DR and inhibited after MSC treatment. Consistent with in vivo evidence, MSCs drove BV2 microglia toward M2 phenotype in vitro. Overexpression of HMGB1 in microglia reversed the effects of MSC treatment, suggesting HMGB1/TLR4 pathway is necessary for MSCs' regulatory effects on microglia polarization. Collectively, MSCs exert beneficial effects on DR by polarizing microglia from M1 toward M2 phenotype via inhibiting the HMGB1/TLR4 signaling pathway.

Advances in Research Related to MicroRNA for Diabetic Retinopathy

Diabetic retinopathy (DR) is a severe microvascular complication of diabetes and is one of the primary causes of blindness in the working-age population in Europe and the United States. At present, no cure is available for DR, but early detection and timely intervention can prevent the rapid progression of the disease. Several treatments for DR are known, primarily ophthalmic treatment based on glycemia, blood pressure, and lipid control, which includes laser photocoagulation, glucocorticoids, vitrectomy, and antivascular endothelial growth factor (anti-VEGF) medications. Despite the clinical efficacy of the aforementioned therapies, none of them can entirely shorten the clinical course of DR or reverse retinopathy. MicroRNAs (miRNAs) are vital regulators of gene expression and participate in cell growth, differentiation, development, and apoptosis. MicroRNAs have been shown to play a significant role in DR, particularly in the molecular mechanisms of inflammation, oxidative stress, and neurodegeneration. The aim of this review is to systematically summarize the signaling pathways and molecular mechanisms of miRNAs involved in the occurrence and development of DR, mainly from the pathogenesis of oxidative stress, inflammation, and neovascularization. Meanwhile, this article also discusses the research progress and application of miRNA-specific therapies for DR.

New Nitinol-based Thermomechanically Adjustable IOL Technology

PURPOSE

To evaluate the feasibility of new adjustable intraocular lens (IOL) technology.

METHODS

The foldable adjustable IOL consists of a nitinol mechanism placed in a haptic-optic cradle. Heating actuators on the nitinol mechanism with a continuous green laser achieve controlled movement of the mechanism and optic. Activation occurs in controlled steps: rotation in 1-degree steps over 360 degrees, and anterior posterior movement in 0.25-diopter (D) steps with a range of +1.50 D. The IOL was tested in vitro and in vivo in a rabbit eye. Foldability and unfolding were demonstrated through a 2.6-mm cartridge.

RESULTS

The adjustable lens mechanism was successfully tested in vitro and in vivo. Activation resulted in a change in optic position relative to the haptics and the capsular bag. Activation of the lever and ratchet mechanism showed radial advancement of the IOL clockwise and counterclockwise. In vivo rotatory movement was achieved after activation by the argon laser at 1 week after implantation. Anterior to posterior movement was accomplished by activating the circular spring actuator mechanism in the laboratory model. Uneventful folding and unfolding were performed.

CONCLUSIONS

A new adjustable IOL with a mechanism that responds in measured steps had been shown to move as planned after activation by argon laser. This was successful in the laboratory in both radial and anterior posterior movement. The radial movement was also proven in vivo in an animal model. Further refinement of the prototype is currently being undertaken. [J Refract Surg. 2023;39(10):662-667.].

Endothelial to mesenchymal cell transition in diabetic retinopathy: targets and therapeutics

Diabetic retinopathy (DR) is a result of neurovacular insults from hyperglycemia in diabetes mellitus (DM), and it is one of the top causes of vision loss throughout the modern world. This review article explores the role endothelial to mesenchymal transition (EndMT) has on the pathogenesis of DR. EndMT contributes to the disruption of the blood-retinal barrier, vascular leakage, neovascularization, and fibrosis observed in DR. Risk factors and biomarkers associated with DR severity are discussed, highlighting the importance of early detection and targeted therapies. Current treatments primarily focus on anti-vascular endothelial growth factor (anti-VEGF) agents, corticosteroids, and laser photocoagulation. However, emerging therapeutic strategies aimed at inhibiting EndMT and its downstream effects show promise in preventing the development and progression of DR. Understanding the molecular and cellular mechanisms underlying EndMT in DR provides valuable insights into the disease process and offers potential options for the development of potential treatments.

Diabetic Retinopathy – Diagnostics and Treatment Guidelines

Diabetic retinopathy is one of the most common complications of diabetes mellitus and represents a serious health, social and economic problem. With the expected increase in the number of patients with diabetes, it is becoming the leading cause of severe vision loss in the working-age population.  The presented guidelines summarize the current knowledge about this disease in order to standardize and update the procedures for the diagnosis, classification and treatment of diabetic retinopathy.

Laser Treatment Modalities for Diabetic Retinopathy

Diabetes is a chronic progressive metabolic disorder that is caused by the body's inability to regulate blood glucose levels. If uncontrolled, it can lead to various complications. Among its various complications, long-term diabetes leads to diabetic retinopathy (DR). It is a disease involving blood vessels and the destruction of retinal nerves. It is usually classified into two types: proliferative diabetic retinopathy (PDR) and nonproliferative diabetic retinopathy (NPDR). It progresses and causes loss of vision. The leading cause of loss of vision is diabetic macular edema (DME). The argon laser is used as a modality in the management of PDR. There are various types of laser photocoagulation, such as peripheral retinal laser photocoagulation, focal macular laser photocoagulation, and grid photocoagulation. DR results in various adverse consequences such as vitreous hemorrhage, fibrosis, traction, detachment of the retina, and glaucoma. To assess DR, a detailed fundus examination with a slit lamp biomicroscope needs to be done. Seven-standard field stereoscopic-color fundus photography needs to be done for documentation and follow-up. Patients with diabetes mellitus (DM) type 1 have a greater risk of suffering from DR. Another major complication of the condition is DME, which is characterized by an increase in the permeability of vessels and the thickening of the central part of the retina along with the accumulation of hard exudates on the macula. This article discusses various laser therapy modalities for the treatment of DR, their types, mechanisms, and aims. Clinical features of DR include abnormal dilatation of capillaries, and outpouchings in the form of microaneurysm from the capillary wall are one of the earliest and most dangerous changes; later, non-perfusion of the retina occurs, which is associated with cotton wool spots and blot hemorrhages. In patients suffering from PDR and maculopathy, peripheral retinal laser photocoagulation is used as a mode of intervention.

Ophthalmologists' and patients' perspectives on treatments for diabetic retinopathy and maculopathy in Vietnam: a descriptive qualitative study

INTRODUCTION

Globally, diabetic retinopathy (DR) is the leading cause of blindness in working-aged adults. Early detection and treatment of DR is essential for preventing sight loss. Services must be available, accessible and acceptable to patients if we are to ensure they seek such care.

OBJECTIVES

To understand patients' knowledge and attitudes towards laser versus antivascular endothelial growth factor (VEGF) injections to treat DR in Vietnam, and to identify factors Vietnamese ophthalmologists consider when making treatment decisions.

METHODS

This is a descriptive qualitative study based on semi-structured interviews with 18 patients (12 from Ho Chi Minh City and 6 from Hanoi) plus individual interviews with 24 ophthalmologists working in eye clinics in these cities. Thematic analysis was used to analyse the data.

RESULTS

In total, 10/24 (41.7%) ophthalmologists were female, and their median age was 41 years (range 29-69 years). The median age of patients was 56.5 years (range 28-72 years), and 7/18 (38.9%) were female. Briefly, factors that influence DR treatment decisions for ophthalmologists are medical considerations (ie, severity of disease, benefits and risks), availability (ie, treatment and resources) and patient-related factors (ie, costs and adherence). Patient's perceived barriers and facilitators to treatments were based on patient and family related factors (ie, treatment and transportation costs) and previous treatment experiences (ie, positive and negative). Recommendations by all participants included ensuring that both laser and anti-VEGF injections are widely available across the country and controlling costs for patients and the healthcare system.

CONCLUSIONS

Reducing DR treatment costs, optimising treatments options, and expanding the network of clinics offering treatment outside metropolitan areas were the main issues raised by participants. These findings can help inform policy changes in Vietnam and may be generalisable to other low-resource settings.

Update on Management of Non-proliferative Diabetic Retinopathy without Diabetic Macular Edema; Is There a Paradigm Shift?

Diabetic retinopathy (DR) is the major cause of visual impairment and blindness in the working-age population. Conventional management for nonproliferative diabetic retinopathy (NPDR) without diabetic macular edema (DME) is derived from the findings of the Early Treatment Diabetic Retinopathy Study (ETDRS). Although the ETDRS protocol basically includes observation, selected cases of severe NPDR may undergo scatter laser photocoagulation. Post-hoc analysis of recent trials has shown that patients with NPDR receiving intravitreal anti-vascular endothelial growth factor (anti-VEGF) for DME would experience improvement in the DR severity scale (DRSS). In addition, recent randomized trials (PANORAMA and Protocol W) have revealed that early intervention with intravitreal aflibercept in eyes with moderately severe to severe NPDR is associated with significant improvement in DRSS and reduced vision-threatening complications of DR. Based on recent studies, it seems that the therapeutic approach to NPDR may undergo a substantial change and a paradigm shift toward considering early intervention with the administration of intravitreal anti-VEGF injections. However, the long-term results and the duration of adherence to anti-VEGF therapy for eyes with NPDR are not yet defined. It is also not apparent whether improvement in DRSS is a true disease modification. Studies showed that DRSS improvement is not associated with retinal reperfusion. In addition, DRCR.net Protocol W showed no visual acuity benefit with the early intravitreal aflibercept injection in moderate to severe NPDR as compared with performing observation plus intravitreal aflibercept applied only after progression to proliferative DR or vision-impairing DME. The cost-benefit ratio is also a challenge. Herein, we look at different aspects of early anti-VEGF application and discuss its pros and cons in the process of treating NPDR.

Efficacy and Safety of Various Treatments for Proliferative Diabetic Retinopathy: A Systematic Review and Network Meta-Analysis

Diabetic retinopathy is the main cause of visual impairment and blindness. The proliferative diabetic retinopathy at the severe stage of diabetic retinopathy is more harmful to vision and even leads to total blindness. To evaluate the visual acuity, central retinal thickness, and adverse reactions of various treatments for proliferative diabetic retinopathy through a systematic network meta-analysis. The relevant research published in English or Chinese from January 1, 2011, to February 1, 2021, was systematically searched by using PubMed, science network, EMBASE, MEDLINE, Cochrane Library, China National Knowledge Infrastructure, Wanfang, and other electronic databases. A total of 15 studies were selected, including 3,222 eyes of PDR patients. Our results show that in terms of visual score improvement, ranibizumab alone (69.90%) and laser + ranibizumab (67.90%) are the best. However, if the groups were grouped again according to the dose and times of ranibizumab injection, the results showed that 0.5 mg ranibizumab injection per month (58.0%) had the best effect on vision improvement. For the change of central retinal thickness, the thickness decreased the most after the laser combined with ranibizumab (96.5%). After the same subgroup analysis, the results were further refined into the best effect of laser combined with 0.3 mg ranibizumab per quarter (72.7%). In addition, our analysis of complications also showed that the overall incidence of adverse reactions of PRP (11.1 ± 12.4, %) was greater than that of ranibizumab (10.6 ± 13.0, %). However, more high-quality randomized controlled trials with longer follow-up using standard methods are still needed to verify the correlation.

Diabetic retinopathy and diabetic macular oedema pathways and management: UK Consensus Working Group

The management of diabetic retinopathy (DR) has evolved considerably over the past decade, with the availability of new technologies (diagnostic and therapeutic). As such, the existing Royal College of Ophthalmologists DR Guidelines (2013) are outdated, and to the best of our knowledge are not under revision at present. Furthermore, there are no other UK guidelines covering all available treatments, and there seems to be significant variation around the UK in the management of diabetic macular oedema (DMO). This manuscript provides a summary of reviews the pathogenesis of DR and DMO, including role of vascular endothelial growth factor (VEGF) and non-VEGF cytokines, clinical grading/classification of DMO vis a vis current terminology (of centre-involving [CI-DMO], or non-centre involving [nCI-DMO], systemic risks and their management). The excellent UK DR Screening (DRS) service has continued to evolve and remains world-leading. However, challenges remain, as there are significant variations in equipment used, and reproducible standards of DMO screening nationally. The interphase between DRS and the hospital eye service can only be strengthened with further improvements. The role of modern technology including optical coherence tomography (OCT) and wide-field imaging, and working practices including virtual clinics and their potential in increasing clinic capacity and improving patient experiences and outcomes are discussed. Similarly, potential roles of home monitoring in diabetic eyes in the future are explored. The role of pharmacological (intravitreal injections [IVT] of anti-VEGFs and steroids) and laser therapies are summarised. Generally, IVT anti-VEGF are offered as first line pharmacologic therapy. As requirements of diabetic patients in particular patient groups may vary, including pregnant women, children, and persons with learning difficulties, it is important that DR management is personalised in such particular patient groups. First choice therapy needs to be individualised in these cases and may be intravitreal steroids rather than the standard choice of anti-VEGF agents. Some of these, but not all, are discussed in this document.

Multimodal imaging interpreted by graders to detect re-activation of diabetic eye disease in previously treated patients: the EMERALD diagnostic accuracy study

BACKGROUND

Owing to the increasing prevalence of diabetes, the workload related to diabetic macular oedema and proliferative diabetic retinopathy is rising, making it difficult for hospital eye services to meet demands.

OBJECTIVE

The objective was to evaluate the diagnostic performance, cost-effectiveness and acceptability of a new pathway using multimodal imaging interpreted by ophthalmic graders to detect reactivation of diabetic macular oedema/proliferative diabetic retinopathy in previously treated patients.

DESIGN

This was a prospective, case-referent, cross-sectional diagnostic study.

SETTING

The setting was ophthalmic clinics in 13 NHS hospitals.

PARTICIPANTS

Adults with type 1 or type 2 diabetes with previously successfully treated diabetic macular oedema/proliferative diabetic retinopathy in one/both eyes in whom, at the time of enrolment, diabetic macular oedema/proliferative diabetic retinopathy could be active or inactive.

METHODS

For the ophthalmic grader pathway, review of the spectral domain optical coherence tomography scans to detect diabetic macular oedema, and seven-field Early Treatment Diabetic Retinopathy Study/ultra-wide field fundus images to detect proliferative diabetic retinopathy, by trained ophthalmic graders. For the current standard care pathway (reference standard), ophthalmologists examined patients face to face by slit-lamp biomicroscopy for proliferative diabetic retinopathy and, in addition, spectral domain optical coherence tomography imaging for diabetic macular oedema.

OUTCOME MEASURES

The primary outcome measure was sensitivity of the ophthalmic grader pathway to detect active diabetic macular oedema/proliferative diabetic retinopathy. The secondary outcomes were specificity, agreement between pathways, cost-consequences, acceptability and the proportion of patients requiring subsequent ophthalmologist assessment, unable to undergo imaging and with inadequate quality images/indeterminate findings. It was assumed for the main analysis that all patients in whom graders diagnosed active disease or were 'unsure' or images were 'ungradable' required examination by an ophthalmologist.

RESULTS

Eligible participants with active and inactive diabetic macular oedema (152 and 120 participants, respectively) and active and inactive proliferative diabetic retinopathy (111 and 170 participants, respectively) were recruited. Under the main analysis, graders had a sensitivity of 97% (142/147) (95% confidence interval 92% to 99%) and specificity of 31% (35/113) (95% confidence interval 23% to 40%) to detect diabetic macular oedema. For proliferative diabetic retinopathy, graders had a similar sensitivity and specificity using seven-field Early Treatment Diabetic Retinopathy Study [sensitivity 85% (87/102), 95% confidence interval 77% to 91%; specificity 48% (77/160), 95% confidence interval 41% to 56%] or ultra-wide field imaging [sensitivity 83% (87/105), 95% confidence interval 75% to 89%; specificity 54% (86/160), 95% confidence interval 46% to 61%]. Participants attending focus groups expressed preference for face-to-face evaluations by ophthalmologists. In the ophthalmologists' absence, patients voiced the need for immediate feedback following grader's assessments, maintaining periodic evaluations by ophthalmologists. Graders and ophthalmologists were supportive of the new pathway. When compared with the reference standard (current standard pathway), the new grader pathway could save £1390 per 100 patients in the review of people with diabetic macular oedema and, depending on the imaging modality used, between £461 and £1189 per 100 patients in the review of people with proliferative diabetic retinopathy.

CONCLUSIONS

For people with diabetic macular oedema, the ophthalmic grader pathway appears safe and cost saving. The sensitivity of the new pathway to detect active proliferative diabetic retinopathy was lower, but may still be considered acceptable for patients with proliferative diabetic retinopathy previously treated with laser. Suggestions from focus group discussions should be taken into consideration if the new pathway is introduced to ensure its acceptability to users.

LIMITATIONS

Lack of fundus fluorescein angiography to confirm diagnosis of active proliferative diabetic retinopathy.

FUTURE WORK

Could refinement of the new pathway increase its sensitivity to detect proliferative diabetic retinopathy? Could artificial intelligence be used for automated reading of images in this previously treated population?

TRIAL REGISTRATION

Current Controlled Trials ISRCTN10856638 and ClinicalTrials.gov NCT03490318.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology AssessmentVol. 25, No. 32. See the NIHR Journals Library website for further project information.

Modeling of Fundus Laser Exposure for Estimating Safe Laser Coagulation Parameters in the Treatment of Diabetic Retinopathy

A personalized medical approach can make diabetic retinopathy treatment more effective. To select effective methods of treatment, deep analysis and diagnostic data of a patient’s fundus are required. For this purpose, flat optical coherence tomography images are used to restore the three-dimensional structure of the fundus. Heat propagation through this structure is simulated via numerical methods. The article proposes algorithms for smooth segmentation of the retina for 3D model reconstruction and mathematical modeling of laser exposure while considering various parameters. The experiment was based on a two-fold improvement in the number of intervals and the calculation of the root mean square deviation between the modeled temperature values and the corresponding coordinates shown for the convergence of the integro-interpolation method (balance method). By doubling the number of intervals for a specific spatial or temporal coordinate, a decrease in the root mean square deviation takes place between the simulated temperature values by a factor of 1.7–5.9. This modeling allows us to estimate the basic parameters required for the actual practice of diabetic retinopathy treatment while optimizing for efficiency and safety. Mathematical modeling is used to estimate retina heating caused by the spread of heat from the vascular layer, where the temperature rose to 45 °C in 0.2 ms. It was identified that the formation of two coagulates is possible when they are located at least 180 μm from each other. Moreover, the distance can be reduced to 160 μm with a 15 ms delay between imaging.

A pilot study: effectiveness of local injection of autologous platelet-rich plasma in treating women with stress urinary incontinence

The study aims to evaluate the effectiveness of local injection of autologous platelet rich plasma (A-PRP) as a treatment for women suffering from stress urinary incontinence (SUI). In a prospective intervention study, twenty consecutive women suffering from SUI were treated with A-PRP injection at anterior vaginal wall where mid-urethra locates. Self-reported questionnaires were used to measure pre-treatment, 1 month and 6 months post-treatment symptom severity. Secondary outcomes of sexual function and treatment effect sorted by age were analyzed with valid statistical methods. A-PRP is effective in relieving SUI symptoms at both 1 month and 6 months post-treatment without significant adverse reactions reported. It seems to have a trend that treatment success rate with cured and improved symptoms was slightly higher in the younger group, although it did not reach statistical significance (P = 0.07). No significant changes in sexual function before and after the treatment were reported by the patients. This pilot study is the first to report A-PRP treatment effect for SUI in women. The result suggested that A-PRP is a considerable treatment option for mild to moderate SUI cases. It also opens up further research opportunities for A-PRP’s clinical applications.

Effectiveness of interventions to increase uptake and completion of treatment for diabetic retinopathy in low- and middle-income countries: a rapid review protocol

BACKGROUND

Vision loss due to diabetic retinopathy can largely be prevented or delayed through treatment. Patients with vision-threatening diabetic retinopathy are typically offered laser or intravitreal injections which often require more than one treatment cycle. However, treatment is not always initiated, or it is not completed, resulting in poor visual outcomes. Interventions aimed at improving the uptake or completion of treatment for diabetic retinopathy can potentially help prevent or delay visual loss in people with diabetes.

METHODS

We will search MEDLINE, Embase, Global Health and Cochrane Register of Studies for studies reporting interventions to improve the uptake of treatment for diabetic retinopathy (DR) and/or diabetic macular oedema (DMO), compared with usual care, in adults with diabetes. The review will include studies published in the last 20 years in the English language. We will include any study design that measured any of the following outcomes in relation to treatment uptake and completion for DR and/or DMO: (1) proportion of patients initiating treatment for DR and/or DMO among those to whom it is recommended, (2) proportion of patients completing treatment for DR and/or DMO among those to whom it is recommended, (3) proportion of patients completing treatment for DR and/or DMO among those initiating treatment and (4) number and proportion of DR and/or DMO rounds of treatment completed per patient, as dictated by the treatment protocol. For included studies, we will also report any measures of cost-effectiveness when available. Two reviewers will screen search results independently. Risk of bias assessment will be done by two reviewers, and data extraction will be done by one reviewer with verification of 10% of the papers by a second reviewer. The results will be synthesised narratively.

DISCUSSION

This rapid review aims to identify and synthesise the peer-reviewed literature on the effectiveness of interventions to increase uptake and completion of treatment for DR and/or DMO in LMICs. The rapid review methodology was chosen in order to rapidly synthesise the available evidence to support programme implementers and policy-makers in designing evidence-based health programmes and public health policy and inform the allocation of resources.

SYSTEMATIC REVIEW REGISTRATION

OSF osf.io/h5wgr.

Intravitreal steroids for macular edema in diabetes

BACKGROUND

Diabetic macular edema (DME) is secondary to leakage from diseased retinal capillaries with thickening of central retina, and is an important cause of poor central visual acuity in people with diabetic retinopathy. Intravitreal steroids have been used to reduce retinal thickness and improve vision in people with DME.

OBJECTIVES

To assess the effectiveness and safety of intravitreal steroid therapy compared with other treatments for DME.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase on 15 May, 2019. We also searched reference lists, Science Citation Index, conference proceedings, and relevant trial registers. We conducted a top up search on 21 October, 2020.

SELECTION CRITERIA

We included randomized controlled trials that evaluated any type of intravitreal steroids as monotherapy against any other intervention (e.g. observation, laser photocoagulation, anti-vascular endothelial growth factor (antiVEGF) for DME.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility and risk of bias and extracted data. Where appropriate, we performed meta-analyses.

MAIN RESULTS

We included 10 trials (4348 participants, 4505 eyes). These trials compared intravitreal steroid therapies versus other treatments, including intravitreal antiVEGF therapy, laser photocoagulation, and sham injection. Most trials had an overall unclear or high risk of bias. One trial (701 eyes ) compared intravitreal dexamethasone implant 0.7mg with sham. We found moderate-certainty evidence that dexamethasone leads to slightly more improvement of visual acuity than sham at 12 months (mean difference [MD] -0.08 logMAR, 95% confidence interval [CI] -0.12 to -0.05 logMAR). Regarding improvement of three or more lines of visual acuity, there was moderate-certainty evidence in favor of dexamethasone at 12 months, but the CI covered the null value (risk ratio (RR) 1.39, 95% CI 0.91 to 2.12). Regarding adverse events, dexamethasone increased by about four times the risk of cataract progression and the risk of using intraocular pressure (IOP)-lowering medications compared to sham (RR 3.89, 95% CI 2.75 to 5.50 and RR 4.54, 95% CI 3.19 to 6.46, respectively; moderate-certainty evidence); about 4 in 10 participants treated with dexamethasone needed IOP-lowering medications. Two trials (451 eyes) compared intravitreal dexamethasone implant 0.7mg with intravitreal antiVEGF (bevacizumab and ranibizumab). There was moderate-certainty evidence that visual acuity improved slightly less with dexamethasone compared with antiVEGF at 12 months (MD 0.07 logMAR, 95% CI 0.04 to 0.09 logMAR; 2 trials; 451 participants/eyes; I² = 0%). The RR of gain of three or more lines of visual acuity was inconsistent between trials, with one trial finding no evidence of a difference between dexamethasone and bevacizumab at 12 months (RR 0.99, 95% CI 0.70 to 1.40; 1 trial; 88 eyes), and the other, larger trial finding the chances of vision gain were half with dexamethasone compared with ranibizumab (RR 0.50, 95% CI 0.32 to 0.79; 1 trial; 432 participants). The certainty of evidence was low. Cataract progression and the need for IOP-lowering medications increased more than 4 times with dexamethasone implant compared to antiVEGF (moderate-certainty evidence). One trial (560 eyes) compared intravitreal fluocinolone implant 0.19mg with sham. There was moderate-certainty evidence that visual acuity improved slightly more with fluocinolone at 12 months (MD -0.04 logMAR, 95% CI -0.06 to -0.01 logMAR). There was moderate-certainty evidence that an improvement in visual acuity of three or more lines was more common with fluocinolone than with sham at 12 months (RR 1.79, 95% CI 1.16 to 2.78). Fluocinolone also increased the risk of cataract progression (RR 1.63, 95% CI 1.35 to 1.97; participants = 335; moderate-certainty evidence), which occurred in about 8 in 10 participants, and the use of IOP-lowering medications (RR 2.72, 95% CI 1.87 to 3.98; participants = 558; moderate-certainty evidence), which were needed in 2 to 3 out of 10 participants. One small trial with 43 participants (69 eyes) compared intravitreal triamcinolone acetonide injection 4 mg with sham. There may be a benefit in visual acuity at 24 months (MD -0.11 logMAR, 95% CI -0.20 to -0.03 logMAR), but the certainty of evidence is low. Differences in adverse effects were poorly reported in this trial. Two trials (615 eyes) compared intravitreal triamcinolone acetonide injection 4mg with laser photocoagulation and reached discordant results. The smaller trial (31 eyes followed up to 9 months) found more visual acuity improvement with triamcinolone (MD -0.18 logMAR, 95% CI -0.29 to -0.07 logMAR), but a larger, multicenter trial (584 eyes, 12-month follow-up) found no evidence of a difference regarding change in visual acuity (MD 0.02 logMAR, 95% CI -0.03 to 0.07 logMAR) or gain of three or more lines of visual acuity (RR 0.85, 95% CI 0.55 to 1.30) (overall low-certainty evidence). Cataract progression was about three times more likely (RR 2.68, 95% CI 2.21 to 3.24; moderate-certainty evidence) and the use of IOP-lowering medications was about four times more likely (RR 3.92, 95% CI 2.59 to 5.96; participants = 627; studies = 2; I² = 0%; moderate-certainty evidence) with triamcinolone. About 1 in 3 participants needed IOP-lowering medication. One small trial (30 eyes) compared intravitreal triamcinolone acetonide injection 4mg with intravitreal antiVEGF (bevacizumab or ranibizumab). Visual acuity may be worse with triamcinolone at 12 months (MD 0.18 logMAR, 95% CI 0.10 to 0.26 logMAR); the certainty of evidence is low. Adverse effects were poorly reported in this trial. Four trials reported data on pseudophakic participants, for whom cataract is not a concern. These trials found no decrease in visual acuity in the second treatment year due to cataract progression.

AUTHORS' CONCLUSIONS

Intravitreal steroids may improve vision in people with DME compared to sham or control. Effects were small, about one line of vision or less in most comparisons. More evidence is available for dexamethasone or fluocinolone implants when compared to sham, and the evidence is limited and inconsistent for the comparison of dexamethasone with antiVEGF treatment. Any benefits should be weighed against IOP elevation, the use of IOP-lowering medication and, in phakic patients, the progression of cataract. The need for glaucoma surgery is also increased, but remains rare.

Retinal laser photocoagulation in management of eales' disease

Eales’ disease is an idiopathic occlusive inflammatory vasculopathy resulting in peripheral retinal ischemia, neovascularization, recurrent hemophthalmos, and proliferative tissue formation. It is often complicated by tractional retinal detachment, secondary glaucoma, and central retinal vein occlusion. The management of patients with Eales’ disease includes mainly glucocorticosteroid therapy, the use of angiogenesis inhibitors, vitreoretinal surgery and laser photocoagulation. The clinical case reported demonstrates the potential of retinal laser photocoagulation for treatment of the Eales’ disease in the ischemic and proliferative stages. The results of retinal laser photocoagulation used as monotherapy demonstrate the clinical and functional indices improvement: enhanced visual acuity, stabilized central retinal sensitivity value, restored clarity to the ocular media, regression of neovascularization and macular edema in the patient’s eye being in the proliferative (3b) stage, and the process stabilization in the eye being in the ischemic (2a) stage of the disease.

Hyaluronic acid coating of gold nanoparticles for intraocular drug delivery: Evaluation of the surface properties and effect on their distribution

Due to the unique anatomical structure of the eye, ocular drug delivery is a promising delivery route for the treatment of several ocular diseases, such as the ocular neovascularization that contributes to diabetic retinopathy. This disease is triggered by inflammation, retinal ischemia, and/or deposits of advanced-glycation end-products (AGEs), as well as increased levels of vascular endothelial growth factor (VEGF), interleukins, or reactive oxygen species (ROS). Gold has unique antioxidant and antiangiogenic properties and can inhibit angiogenic molecules. Furthermore, gold nanoparticles (GNPs) are not only biocompatible, they are easy to synthesize, they absorb and scatter visible light, and they can be made with precise control over size and shape. GNPs are an excellent candidate for ocular drug delivery because they can be conjugated to an extraordinarily diverse array of different biomolecules, and surface functionalization can improve the mobility of GNPs across the physiological barriers of the eye, such as the vitreous humour or the inner limiting membrane. For this purpose, we employed low molecular weight hyaluronan (HA) to increase the mobility of the nanoparticles as well as target them to HA receptors that are expressed in different cells of the eye. In this study, the combination of gold and HA enhanced the stability of the whole carrier and promoted their distribution across ocular tissues and barriers to reach the retina. Moreover, analysis in vitro, ex vivo, and in ovo revealed the protective and antiangiogenic effect of GNPs as inhibitors of AGEs-mediated- retinal pigment epithelial cell death and neovascularization. We demonstrated that conjugation with HA enhances GNP stability and distribution due to a specific CD44 receptor interaction. The capacity of HA-GNPs to distribute through the vitreous humour and their avidity for the deeper retinal layers ex vivo, suggest that HA-GNPs are a promising delivery system for the treatment of ocular neovascularization and related disorders.

Comparison of Subthreshold 577 and 810 nm Micropulse Laser Effects on Heat-Shock Protein Activation Kinetics: Implications for Treatment Efficacy and Safety

Purpose

To compare the safety and efficacy of 810 versus 577 nm laser wavelengths for micropulse subthreshold (sublethal) laser treatment by mathematical analysis.

Methods

Two different representative laser parameter sets for micropulsed subthreshold diode laser treatment, one employing 810 nm and the other 577 nm, are compared with regard to efficacy by analysis of the kinetics of laser-induced heat-shock protein (HSP) activation; and for safety, by scaling law analysis.

Results

Kinetics analysis of laser-induced HSP activation shows that the primary therapeutic effect of laser is thermal incitement of a long-term wavelength-independent increase in the rate of HSP-mediated protein repair specific to sick and dysfunctional cells, rather than from short-term increases in free intracellular HSP concentrations. Scaling law analysis of the same 810 and 577 nm laser parameters, however, finds treatment safety highly wavelength-sensitive, favoring 810 over 577 nm.

Conclusions

Mathematical analyses of the effects retinal laser-induced HSP activation provide important insights into the mechanism of action and the importance of wavelength selection in modern retinal laser therapy. Our analyses find 810 and 577 nm to be equally effective, but 810 nm having a significantly wider therapeutic range/safety margin, and thus less likely to cause inadvertent, and thus unpredictable, laser-induced retinal damage, than 577 nm.

Translational Relevance

Mathematical analysis of enzyme reaction kinetics provides important insights into the mechanism of action and clinical implications of wavelength selection in modern retinal laser therapy.

The Evolving Treatment of Diabetic Retinopathy

Purpose

To review the current therapeutic options for the management of diabetic retinopathy (DR) and diabetic macular edema (DME) and examine the evidence for integration of laser and pharmacotherapy.

Methods

A review of the PubMed database was performed using the search terms diabetic retinopathy, diabetic macular edema, neovascularization, laser photocoagulation, intravitreal injection, vascular endothelial growth factor (VEGF), vitrectomy, pars plana vitreous surgery, antiangiogenic therapy. With additional cross-referencing, this yielded 835 publications of which 301 were selected based on content and relevance.

Results

Many recent studies have evaluated the pharmacological, laser and surgical therapeutic strategies for the treatment and prevention of DR and DME. Several newer diagnostic systems such as optical coherence tomography (OCT), microperimetry, and multifocal electroretinography (mfERG) are also assisting in further refinements in the staging and classification of DR and DME. Pharmacological therapies for both DR and DME include both systemic and ocular agents. Systemic agents that promote intensive glycemic control, control of dyslipidemia and antagonists of the renin-angiotensin system demonstrate beneficial effects for both DR and DME. Ocular therapies include anti-VEGF agents, corticosteroids and nonsteroidal anti-inflammatory drugs. Laser therapy, both as panretinal and focal or grid applications continue to be employed in management of DR and DME. Refinements in laser devices have yielded more tissue-sparing (subthreshold) modes in which many of the benefits of conventional continuous wave (CW) lasers can be obtained without the adverse side effects. Recent attempts to lessen the burden of anti-VEGF injections by integrating laser therapy have met with mixed results. Increasingly, vitreoretinal surgical techniques are employed for less advanced stages of DR and DME. The development and use of smaller gauge instrumentation and advanced anesthesia agents have been associated with a trend toward earlier surgical intervention for diabetic retinopathy. Several novel drug delivery strategies are currently being examined with the goal of decreasing the therapeutic burden of monthly intravitreal injections. These fall into one of the five categories: non-biodegradable polymeric drug delivery systems, biodegradable polymeric drug delivery systems, nanoparticle-based drug delivery systems, ocular injection devices and with sustained release refillable devices. At present, there remains no one single strategy for the management of the particular stages of DR and DME as there are many options that have not been rigorously tested through large, randomized, controlled clinical trials.

Conclusion

Pharmacotherapy, both ocular and systemic, will be the primary mode of intervention in the management of DR and DME in many cases when cost and treatment burden are less constrained. Conventional laser therapy has become a secondary intervention in these instances, but remains a first-line option when cost and treatment burden are more constrained. Results with subthreshold laser appear promising but will require more rigorous study to establish its role as adjunctive therapy. Evidence to support an optimal integration of the various treatment options is lacking. Central to the widespread adoption of any therapeutic regimen for DR and DME is substantiation of safety, efficacy, and cost-effectiveness by a body of sound clinical trials.

American Society of Retina Specialists Clinical Practice Guidelines on the Management of Nonproliferative and Proliferative Diabetic Retinopathy without Diabetic Macular Edema

Purpose

Nonproliferative (NPDR) and proliferative diabetic retinopathy (PDR) without diabetic macular edema (DME) affect millions of individuals living with diabetes throughout the world. There is increasing data on various management strategies for such patients, but there is limited consensus on how the data should be adopted into clinical practice.

Methods

This literature review and editorial presents and synthesizes the current evidence for various management paradigms for NPDR and PDR without DME.

Results

Retina specialists are an integral member of the diabetes management team, and should encourage patients on the importance of glycemic and cardiovascular optimization for both systemic and retinopathy risk factor reduction. The diabetic retinopathy severity scale (DRSS) is now an approvable endpoint for clinical trials in the United States, therefore becoming more clinically relevant. For PDR without DME, the Diabetic Retinopathy Study (DRS) and the Early Treatment Diabetic Retinopathy Study (ETDRS) established the standard of care with panretinal photocoagulation (PRP). Laser parameters have since evolved to include less intense and earlier intervention. Studies have recently demonstrated that anti-vascular endothelial growth factor (VEGF) treatment of PDR is effective at regressing neovascularization and improving DRSS levels in many patients. Further evidence is required to determine optimal treatment frequency, duration, and retreatment criteria, in the real world. There are concerns for adverse events in patients being lost to follow up during anti-VEGF treatment. For NPDR without DME, the standard of care has been a wait-and-watch approach. Data within the DRS and the ETDRS suggest that PRP for severe NPDR can be an option for select patients as well. Multiple clinical trials have now demonstrated that anti-VEGF treatment can improve the DRSS score in NPDR. Further studies are required to assess whether this positively affects long-term visual outcomes, and whether the benefits outweigh the risks in the real world for routine use.

Conclusions

There is cumulative evidence demonstrating the efficacy of various treatment options for NPDR and PDR without DME. Currently, patients would most likely benefit from thoughtful management strategies that are tailored to the individual patient.

Different lasers and techniques for proliferative diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a chronic progressive disease of the retinal microvasculature associated with prolonged hyperglycaemia. Proliferative DR (PDR) is a sight-threatening complication of DR and is characterised by the development of abnormal new vessels in the retina, optic nerve head or anterior segment of the eye. Argon laser photocoagulation has been the gold standard for the treatment of PDR for many years, using regimens evaluated by the Early Treatment of Diabetic Retinopathy Study (ETDRS). Over the years, there have been modifications of the technique and introduction of new laser technologies.

OBJECTIVES

To assess the effects of different types of laser, other than argon laser, and different laser protocols, other than those established by the ETDRS, for the treatment of PDR. We compared different wavelengths; power and pulse duration; pattern, number and location of burns versus standard argon laser undertaken as specified by the ETDRS.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 5); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 8 June 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of pan-retinal photocoagulation (PRP) using standard argon laser for treatment of PDR compared with any other laser modality. We excluded studies of lasers that are not in common use, such as the xenon arc, ruby or Krypton laser.

DATA COLLECTION AND ANALYSIS

We followed Cochrane guidelines and graded the certainty of evidence using the GRADE approach.

MAIN RESULTS

We identified 11 studies from Europe (6), the USA (2), the Middle East (1) and Asia (2). Five studies compared different types of laser to argon: Nd:YAG (2 studies) or diode (3 studies). Other studies compared modifications to the standard argon laser PRP technique. The studies were poorly reported and we judged all to be at high risk of bias in at least one domain. The sample size varied from 20 to 270 eyes but the majority included 50 participants or fewer.Nd:YAG versus argon laser (2 studies): very low-certainty evidence on vision loss, vision gain, progression and regression of PDR, pain during laser treatment and adverse effects.Diode versus argon laser (3 studies): very-low certainty evidence on vision loss, vision gain, progression and regression of PDR and adverse effects; moderate-certainty evidence that diode laser was more painful (risk ratio (RR) troublesome pain during laser treatment (RR 3.12, 95% CI 2.16 to 4.51; eyes = 202; studies = 3; I² = 0%).0.5 second versus 0.1 second exposure (1 study): low-certainty evidence of lower chance of vision loss with 0.5 second compared with 0.1 second exposure but estimates were imprecise and compatible with no difference or an increased chance of vision loss (RR 0.42, 95% CI 0.08 to 2.04, 44 eyes, 1 RCT); low-certainty evidence that people treated with 0.5 second exposure were more likely to gain vision (RR 2.22, 95% CI 0.68 to 7.28, 44 eyes, 1 RCT) but again the estimates were imprecise . People given 0.5 second exposure were more likely to have regression of PDR compared with 0.1 second laser PRP again with imprecise estimate (RR 1.17, 95% CI 0.92 to 1.48, 32 eyes, 1 RCT). There was very low-certainty evidence on progression of PDR and adverse effects.'Light intensity' PRP versus classic PRP (1 study): vision loss or gain was not reported but the mean difference in logMAR acuity at 1 year was -0.09 logMAR (95% CI -0.22 to 0.04, 65 eyes, 1 RCT); and low-certainty evidence that fewer patients had pain during light PRP compared with classic PRP with an imprecise estimate compatible with increased or decreased pain (RR 0.23, 95% CI 0.03 to 1.93, 65 eyes, 1 RCT).'Mild scatter' (laser pattern limited to 400 to 600 laser burns in one sitting) PRP versus standard 'full' scatter PRP (1 study): very low-certainty evidence on vision and visual field loss. No information on adverse effects.'Central' (a more central PRP in addition to mid-peripheral PRP) versus 'peripheral' standard PRP (1 study): low-certainty evidence that people treated with central PRP were more likely to lose 15 or more letters of BCVA compared with peripheral laser PRP (RR 3.00, 95% CI 0.67 to 13.46, 50 eyes, 1 RCT); and less likely to gain 15 or more letters (RR 0.25, 95% CI 0.03 to 2.08) with imprecise estimates compatible with increased or decreased risk.'Centre sparing' PRP (argon laser distribution limited to 3 disc diameters from the upper temporal and lower margin of the fovea) versus standard 'full scatter' PRP (1 study): low-certainty evidence that people treated with 'centre sparing' PRP were less likely to lose 15 or more ETDRS letters of BCVA compared with 'full scatter' PRP (RR 0.67, 95% CI 0.30 to 1.50, 53 eyes). Low-certainty evidence of similar risk of regression of PDR between groups (RR 0.96, 95% CI 0.73 to 1.27, 53 eyes). Adverse events were not reported.'Extended targeted' PRP (to include the equator and any capillary non-perfusion areas between the vascular arcades) versus standard PRP (1 study): low-certainty evidence that people in the extended group had similar or slightly reduced chance of loss of 15 or more letters of BCVA compared with the standard PRP group (RR 0.94, 95% CI 0.70 to 1.28, 270 eyes). Low-certainty evidence that people in the extended group had a similar or slightly increased chance of regression of PDR compared with the standard PRP group (RR 1.11, 95% CI 0.95 to 1.31, 270 eyes). Very low-certainty information on adverse effects.

AUTHORS' CONCLUSIONS

Modern laser techniques and modalities have been developed to treat PDR. However there is limited evidence available with respect to the efficacy and safety of alternative laser systems or strategies compared with the standard argon laser as described in ETDRS.