Improved outcome after primary vitrectomy in diabetic patients treated with statins. Eur J Ophthalmol. 2016;26:174-181. [PMID: 26350989 DOI: 10.5301/ejo.5000657]

Diabetic retinopathy: emerging concepts of current and potential therapy

Diabetic retinopathy (DR) is one of the leading causes of permanent central blindness worldwide. Despite the complexity and inadequate understanding of DR pathogenesis, many of the underlying pathways are currently partially understood and may offer potential targets for future treatments. Anti-VEGF medications are currently the main medication for this problem. This article provides an overview of the established pharmacological treatments and those that are being developed to cure DR. We firstly reviewed the widely utilized approaches including pan-retinal photocoagulation therapy, anti-VEGF therapy, corticosteroid therapy, and surgical management of DR. Next, we discussed the mechanisms of action and prospective benefits of novel candidate medications. Current management are far from being a perfect treatment for DR, despite mild-term favorable efficiency and safety profiles. Pharmacological research should work toward developing longer-lasting treatments or new drug delivery systems, as well as on identifying new molecular targets in the pathogenetical mechanism for DR. In order to find a treatment that is specifically designed for each patient, it is also necessary to properly characterize patients, taking into account elements like hereditary factors and intraretinal neovascularization stages for effective utilization of drugs. The current and potential approaches for diabetic retinopathy. Image was constructed using Biorender.com.

In Situ Liquid Crystal Gel as a Promising Strategy for Improving Ocular Administration of Dexamethasone: Preparation, Characterization, and Evaluation

The purpose of this study was to design an in situ liquid crystal gel (ISLG) as an ophthalmic drug delivery system for dexamethasone (DEX) to enhance its eye retention and ocular bioavailability. The in situ liquid crystal gels (ISLGs) were prepared using a phytantriol/PEG400/water (65:30:5, w/w) ternary system. Polarized light microscope (PLM), small-angle X-ray scattering (SAXS), and rheology analysis confirmed that the internal structure of the preparations was Pn3m cubic phase liquid crystal gels with pseudoplastic fluid properties. Meanwhile, in vitro release behavior of the preparations conforms to the Higuchi equation. Corneal penetration experiments showed that compared with DEX sodium phosphate eye drops, DEX-ISLGs(F2) produced a 5.45-fold increase in the P_app value, indicating a significant enhancement of corneal penetration. In addition, in vivo experiments have confirmed that the ISLGs have better biocompatibility and longer retention time in the cornea. Simultaneously, corneal hydration level, eye irritation experiments, and histological observations proved the safety of the preparations. Pharmacokinetic studies have shown that the ISLG could maintain the DEX concentration in aqueous humor for at least 12 h after administration, which significantly improves the bioavailability of the drug. Collectively, these results indicated that ISLG would be a potential drug carrier for the treatment of diabetic retinopathy (DR).

Progress of Nanotechnology in Diabetic Retinopathy Treatment

Diabetic retinopathy (DR) is a chronic diabetes complication that progressively manifests itself as blurred vision, eye floaters, distorted vision, and even partial or total loss of vision as a result of retinal detachment in severe cases. Clinically, patients who have undergone variations in the microcirculation of the ocular fundus are treated with laser photocoagulation to improve the circulation of retina; but for patients with macular edema, anti-vascular endothelial growth factor (anti-VEGF) drugs are generally injected to eliminate macular edema and improve vision. The worst cases are patients with fundus hemorrhage or proliferative vitreoretinopathy, for whom vitrectomy has been performed. At present, these clinical treatment methods have widely been used, providing satisfactory results. However, considering the low bioavailability and potential side effects of drugs and the inevitable risks in major surgery, DR prevention, and treatment as well as nerve tissue regeneration in the later stage have always been the focus of research. In recent years, nanotechnology has been increasingly applied in the medical field, leading to new ideas for DR treatment. This study aims to systematically review the research progress of nanotechnology in DR treatment.

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.

Surgical management of diabetic tractional retinal detachments

Tractional retinal detachment is an end-stage form of diabetic retinopathy that occurs when contractile forces in the vitreous and neovascular tissue lead to the detachment of the neurosensory retina. We review the literature related to the management of this disease. Preoperative planning includes appropriate patient selection, diagnostic and prognostic imaging, and medical optimization with reduction of systemic risk factors. Use of antivascular endothelial growth factor for preoperative treatment has had significant benefits for tractional retinal detachment repair in improving surgical efficiency and outcomes. Advances in microsurgical instrumentation are discussed, with attention to small-gauge vitrectomy with improved flow dynamics, viewing strategies, and lighting allowing bimanual surgery. Special emphasis is placed on bimanual surgical technique, choice of tamponade, and the avoidance of iatrogenic damage. Complications and special considerations are further explored. Based on our compilation of relevant literature, we propose a surgical algorithm for the management of these complex patients.

Systemic use of calcium channel blockers associated with less increase in central retinal thickness after uncomplicated cataract surgery

PURPOSE

To examine the role of systemic medication on the risk of pseudophakic cystoid macular edema (PCME) following uneventful cataract surgery.

METHODS

A total of 269 eyes undergoing routine cataract surgery. Spectral-domain optical coherence tomography imaging was conducted before surgery and at 28 days. Information about medication of the participants was gathered from The National Archive of Health Information (Kanta), an electronic pharmaceutical database.

RESULTS

Systemic medication with angiotensin converting enzyme inhibitor/angiotensin II receptor antagonists (p < 0.001), beta-blockers (β-blockers) (p = 0.002), calcium channel blockers (CCBs) (p < 0.001), nitrates (p =0.021) and lipophilic HMG-CoA reductase inhibitors (statins) (p < 0.001) were more frequently prescribed to diabetic compared with nondiabetic patients. In eyes with steroid monotherapy (N = 135), concomitant systemic medication with β-blockers (12.9 ± 24.0 μm versus 28.6 ± 59.5 μm, p = 0.045), CCBs (12.0 ± 22.1 μm versus 26.3 ± 55.6 μm, p = 0.041) and statins (12.9 ± 22.8 μm versus 30.0 ± 61.9 μm, p = 0.038) attenuated a change in central retinal thickness (CRT) when compared to patients not receiving medication. In multivariable analysis, the use of CCBs remained as an independent protective factor against macular swelling at 28 days (-0.23; 95% CI [-0.43 to -0.04]; p = 0.021), when all systemic medications showing statistical significance were included (i.e. β-blockers, CCBs and statins) together with diabetes status. In eyes with nonsteroidal anti-inflammatory drug (NSAID) monotherapy (N = 67) and steroid and NSAID combination therapy (N = 67), CRT increase was moderate both with and without use of systemic medications.

CONCLUSION

Systemic vasoactive medication may be protective against CRT change induced by cataract surgery in eyes at risk of PCME such as those with postoperative steroid monotherapy.

Diabetes Alone Does Not Impair Recovery From Uneventful Cataract Surgery

PURPOSE

To study the outcomes of uneventful cataract surgery in diabetic patients without retinal complications.

DESIGN

A post hoc treatment analysis using data from 2 double-masked randomized clinical trials.

METHODS

Setting: Conducted at Kymenlaakso Central Hospital, Kotka, Finland.

PROCEDURE

A total of 276 eyes of 266 patients undergoing routine cataract surgery were included in the study. Patients with type I or II diabetes (n = 56 eyes) were compared to nondiabetic patients (n = 220 eyes). Clinical evaluation was conducted by the operating physician, and outcome measures taken before surgery and day 28 were recorded by a research technician.

RESULTS

Patient age, sex distribution, and all baseline ophthalmic and surgical parameters were comparable for the nondiabetic and diabetic patient groups. Increase in aqueous flare 6.3 ± 16.4 photon units (pu)/ms vs 3.7 ± 8.9 pu/ms (mean ± standard deviation; P = .282), central retinal thickness (CRT) 12.0 ± 38.2 μm vs 5.9 ± 15.8 μm (P = .256), corrected distance visual acuity 0.57 ± 0.31 decimals vs 0.53 ± 0.35 decimals (P = .259), and patient satisfaction 9.3 ± 0.9 vs 9.2 ± 1.1 (P = .644) were comparable for nondiabetic and diabetic patients. In eyes with steroid monotherapy (n = 64), CRT increased 38.1 ± 72.8 μm in nondiabetic patients compared to 7.8 ± 6.6 μm in diabetic ones (P = .010). In eyes with nonsteroidal anti-inflammatory drug (NSAID) monotherapy (n = 157), CRT increased 5.7 ± 18.4 μm in nondiabetic patients compared to 6.2 ± 20.5 μm in diabetic ones (P = .897). Among eyes with steroid and NSAID combination therapy (n = 55), CRT increased 3.6 ± 4.1 μm in nondiabetic patients compared to 2.9 ± 3.2 μm in diabetic ones (P = .606). At 28 days postsurgery, pseudophakic cystoid macular edema (PCME) was reported in 8 eyes, of which 7 were in nondiabetic patients (P = 1.000).

CONCLUSIONS

Diabetic patients showed less change in CRT when compared to controls in steroid monotherapy. Other outcome measurements shows no statistical differences.

Statins in ophthalmology

Statins, 3-hydroxy-3-methyl-gutaryl coenzyme A reductase inhibitors, are a class of lipid-lowering drugs with anti-inflammatory, immunomodulatory, and vascular effects. Statins are increasingly being used in the treatment of a variety of medical conditions. We examine the actions of statins on the eye and its associated ophthalmic disorders. Statins can be synthetic or nonsynthetic, and their differentiating derivations may contribute to their varying cholesterol-lowering and pleiotropic effects. There is conflicting evidence on the ocular therapeutic and adverse effects of the statins. Statins may play a role in reducing the burden of dry eye, corneal ulcer scarring, thyroid-associated orbitopathy, glaucoma, uveitis and other associated ocular inflammatory states, cataract, proliferative vitreoretinopathy, diabetic retinopathy, macular degeneration, and choroidal melanoma. Topical preparations of statins can be formulated, thereby extending the range of ocular diseases that may be amenable to treatment. Statins have a relatively safe side effect profile, but rare and serious adverse reactions have been reported with their usage in ophthalmology, including myopathies and rhabdomyolysis with acute renal failure.

Statin use and vitreoretinal surgery: Findings from a Finnish population-based cohort study

PURPOSE

Vitreoretinal (VR) surgery is the third most common intraocular surgery after refractive and cataract surgery. The impact of statin therapy on VR surgery outcomes remains unclear, despite a potentially beneficial effect. We explored the association of preoperative statin therapy and the need for revitrectomy after primary vitrectomy.

METHODS

Our historical, population-based, register-based, VR surgery cohort consisted of 5709 patients operated in a tertiary, academic referral hospital in Finland, during 2008-2014, covering 6.5 years. Subgroup analysis was performed as follows: eyes operated due to (i) rhegmatogenous retinal detachment (RRD), (ii) VR interface diseases (macular pucker/hole), (iii) diabetic maculopathy or proliferative retinopathy, (iv) vitreous haemorrhage, (v) lens subluxation, (vi) vitreous opacities or (vii) other VR indication. The primary end-point event was revitrectomy during a postoperative follow-up period of 1 year due to retinal redetachment, vitreous rehaemorrhage, postoperative endophthalmitis, recurrent pucker or unclosed macular hole.

RESULTS

Rhegmatogenous retinal detachment (RRD) was the second most frequent indication of VR surgery, including 1916 patients, with 305 re-operations with rate 0.20 (95% CI 0.18-0.23) per person-year. Statin treatment in time of operation was associated with lower risk of re-operation according to relative scale (incidence rate ratio 0.72, 95% CI 0.53-0.97), but not in absolute scale (incidence rate difference -0.58, 95% CI -4.30 to 3.15 for 100 person-years). No association with statin therapy and vitrectomy outcome was observed in the other VR subgroups.

CONCLUSION

Use of statin treatment was associated with a 28% lower risk of revitrectomy in patients operated due to RRD. Further randomized clinical trials are highly warranted.

Role of lipid-lowering agents in the management of diabetic retinopathy

Diabetic retinopathy affects a substantial proportion of patients with diabetes mellitus (DM) and is the leading cause of blindness in working-aged adults. Even though the incidence of diabetic retinopathy has declined in the last decades, its prevalence increased and is expected to rise further as a result of the increasing incidence of type 2 DM (T2DM) and the longer life expectancy of patients with DM. The pathogenesis of diabetic retinopathy is multifactorial. Some observational studies suggested an association between dyslipidemia and the development and progression of retinopathy in patients with DM but others did not confirm this association. Regarding lipid-lowering agents, studies that evaluated the role of statins in the management of these patients are mostly small and yielded discrepant results. Large randomized studies with statins in patients with T2DM showed no benefit of these agents on diabetic retinopathy but were not designed to address this effect. In contrast, both preclinical data and two large randomized controlled studies, the FIELD and the ACCORD trial, showed that fenofibrate delays the progression of diabetic retinopathy. Even though the mechanisms underpinning this favorable effect are not entirely clear, these findings suggest that fenofibrate might represent a useful tool for the management of diabetic retinopathy.

Surgical treatment for diabetic vitreoretinal diseases: a review

Over the past four decades, advancements in surgical instrumentations and techniques have significantly improved the postoperative anatomical and visual outcomes of patients with various diabetic vitreoretinal diseases. In particular, surgical interventions for previously serious and untreatable blinding proliferative diabetic retinopathy can now be performed, with much better results. The advents of micro incisional vitrectomy system with better visualization system like binocular indirect ophthalmomicroscope and state-of-the-art instrumentation revolutionized the era of diabetic vitrectomy. High-speed vitrectors, finer instruments, chromo-assisted vitrectomy and use of anti-vascular endothelial growth factors not only change the paradigm but also help achieve much better outcome after diabetic vitrectomies. In this review, we will discuss and summarize the indications, surgical considerations, surgical techniques, potential complications and outcomes of vitreoretinal surgery for diabetic eye diseases.