Optical cross-sectional observation of resolved diabetic macular edema associated with vitreomacular separation

A Quantitative Approach to Predict Differential Effects of Anti-VEGF Treatment on Diffuse and Focal Leakage in Patients with Diabetic Macular Edema: A Pilot Study

Purpose

We use semiautomated segmentation of fluorescein angiography (FA) to determine whether anti-vascular endothelial growth factor (VEGF) treatment for diabetic macular edema (DME) differentially affects microaneurysm (MA)–associated leakage, termed focal leakage, versus non-MA–associated leakage, termed diffuse leakage.

Methods

We performed a retrospective study of 29 subjects treated with at least three consecutive injections of anti-VEGF agents for DME (mean 4.6 injections; range, 3–10) who underwent Heidelberg FA before and after anti-VEGF therapy. Inclusion criteria were macula center involving DME and at least 3 consecutive anti-VEGF injections. Exclusion criteria were macular edema due to cause besides DME, anti-VEGF within 3 months of initial FA, concurrent treatment for DME besides anti-VEGF, and macular photocoagulation within 1 year. At each time point, total leakage was semiautomatically segmented using a modified version of our previously published software. Microaneurysms were identified by an expert grader and leakage within a 117 μm radius of each MA was classified as focal leakage. Remaining leakage was classified as diffuse leakage. The absolute and percent changes in total, diffuse, and focal leakage were calculated for each subject.

Results

Mean pretreatment total leakage was 8.2 mm² and decreased by a mean of 40.1% (P < 0.0001; 95% confidence interval [CI], [−28.6, −52.5]) following treatment. Diffuse leakage decreased by a mean of 45.5% (P < 0.0001; 95% CI, [−31.3, −59.6]) while focal leakage decreased by 17.9% (P = 0.02; 95% CI, [−1.0, −34.8]). The difference in treatment response between focal and diffuse leakage was statistically significant (P = 0.01).

Conclusions

Anti-VEGF treatment for DME results in decreased diffuse leakage but had relatively little effect on focal leakage as assessed by FA. This suggests that diffuse leakage may be a marker of VEGF-mediated pathobiology. Patients with predominantly focal leakage may be less responsive to anti-VEGF therapy.

Translational Relevance

Fluorescein angiography can define focal and diffuse subtypes of diabetic macular edema and these may respond differently to anti-VEGF treatment.

Pathophysiology and treatment of diabetic retinopathy

In the past years, the management of diabetic retinopathy (DR) relied primarily on a good systemic control of diabetes mellitus, and as soon as the severity of the vascular lesions required further treatment, laser photocoagulation or vitreoretinal surgery was done to the patient. Currently, even if the intensive metabolic control is still mandatory, a variety of different clinical strategies could be offered to the patient. The recent advances in understanding the complex pathophysiology of DR allowed the physician to identify many cell types involved in the pathogenesis of DR and thus to develop new treatment approaches. Vasoactive and proinflammatory molecules, such as vascular endothelial growth factor (VEGF), play a key role in this multifactorial disease. Current properly designed trials, evaluating agents targeting VEGF or other mediators, showed benefits in the management of DR, especially when metabolic control is lacking. Other agents, directing to the processes of vasopermeability and angiogenesis, are under investigations, giving more hope in the future management of this still sight-threatening disease.

Diabetic macular edema: pathogenesis and treatment

Diabetic macular edema is a major cause of visual impairment. The pathogenesis of macular edema appears to be multifactorial. Laser photocoagulation is the standard of care for macular edema. However, there are cases that are not responsive to laser therapy. Several therapeutic options have been proposed for the treatment of this condition. In this review we discuss several factors and mechanisms implicated in the etiology of macular edema (vasoactive factors, biochemical pathways, anatomical abnormalities). It seems that combined pharmacologic and surgical therapy may be the best approach for the management of macular edema in diabetic patients.

Diabetic macular edema: what is focal and what is diffuse?

PURPOSE

To review the available information on classification of diabetic macular edema (DME) as focal or diffuse.

DESIGN

Interpretive essay.

METHODS

Literature review and interpretation.

RESULTS

The terms focal diabetic macular edema and diffuse diabetic macular edema frequently are used without clear definitions. Published definitions often use different examination methods and often are inconsistent. Evaluating published information on the prevalence of focal and diffuse DME, the responses of focal and diffuse DME to treatments, and the importance of focal and diffuse DME in assessing prognosis is hindered because the terms are used inconsistently. A newer vocabulary may be more constructive, one that describes discrete components of the concepts such as extent and location of macular thickening, involvement of the center of the macula, quantity and pattern of lipid exudates, source of fluorescein leakage, and regional variation in macular thickening and that distinguishes these terms from the use of the term focal when describing one type of photocoagulation technique. Developing methods for assessing component variables that can be used in clinical practice and establishing reproducibility of the methods are important tasks.

CONCLUSIONS

Little evidence exists that characteristics of DME described by the terms focal and diffuse help to explain variation in visual acuity or response to treatment. It is unresolved whether a concept of focal and diffuse DME will prove clinically useful despite frequent use of the terms when describing management of DME. Further studies to address the issues are needed.

A spreadsheet template for the analysis of optical coherence tomography in the longitudinal management of diabetic macular edema

BACKGROUND AND OBJECTIVE

To provide a tool for analyzing optical coherence tomography data in patients with diabetic macular edema.

PATIENTS AND METHODS

Retrospective series of 206 patients with diabetic macular edema involving at least one eye and receiving focal laser photocoagulation, intravitreal triamcinolone acetonide injection, or vitrectomy, membrane peeling, and intravitreal triamcinolone acetonide injection, and of untreated fellow eyes without diabetic macular edema. Main outcome measures included foveal subfield mean thickness and thickening relative to normal (microns), total macular volume and its increase relative to normal (mm3), visual acuity (Snellen decimal), and intraocular pressure (mm Hg).

RESULTS

The authors demonstrate a graphical display of data based on a spreadsheet template for the longitudinal management of diabetic macular edema. Complex relationships of ocular response and interventions are concisely displayed.

CONCLUSION

A graphical display of optical coherence tomography, visual acuity, and intraocular pressure data is a practical aid in the management of diabetic macular edema.

Retinal assessment using optical coherence tomography

Over the 15 years since the original description, optical coherence tomography (OCT) has become one of the key diagnostic technologies in the ophthalmic subspecialty areas of retinal diseases and glaucoma. The reason for the widespread adoption of this technology originates from at least two properties of the OCT results: on the one hand, the results are accessible to the non-specialist where microscopic retinal abnormalities are grossly and easily noticeable; on the other hand, results are reproducible and exceedingly quantitative in the hands of the specialist. However, as in any other imaging technique in ophthalmology, some artifacts are expected to occur. Understanding of the basic principles of image acquisition and data processing as well as recognition of OCT limitations are crucial issues to using this equipment with cleverness. Herein, we took a brief look in the past of OCT and have explained the key basic physical principles of this imaging technology. In addition, each of the several steps encompassing a third generation OCT evaluation of retinal tissues has been addressed in details. A comprehensive explanation about next generation OCT systems has also been provided and, to conclude, we have commented on the future directions of this exceptional technique.

Use of a cyclo-oxygenase 2 inhibitor for prophylaxis of cystoid macular oedema following cataract surgery: a randomized placebo-controlled trial

BACKGROUND

To assess the efficacy of Celecoxib, a cyclo-oxygenase 2 (COX-2) inhibitor, as prophylaxis for cystoid macular oedema after routine cataract surgery.

METHODS

A prospective, randomized, double-blind placebo-controlled trial of 69 hospital patients undergoing cataract surgery. Celecoxib 200 mg twice daily or placebo was given immediately after surgery for 14 days. Optical coherence tomography was used to quantify macular thickness before surgery and on day 1, week 2 and week 6 after surgery.

RESULTS

Sixty-nine patients were enrolled, of which 33 received placebo and 36 received active drug. Clinically apparent cystoid macular oedema occurred in four of the treatment group and two of the placebo group (P = 0.68). No difference in best-corrected visual acuity was seen at 6 weeks (P = 0.37). Covariate analysis of the results at 2 weeks and 6 weeks showed a macular thickness of 3% less in the treatment group compared with placebo (P = 0.050).

CONCLUSION

Celecoxib may decrease macular thickening following routine cataract surgery at 2 and 6 weeks after surgery as measured by Stratus OCT III. No difference in best-corrected visual acuity or clinically apparent cystoid macular oedema was seen. Further investigation of COX-2 inhibitors in a larger prospective randomized trial is required.

Pars plana vitrectomy for refractory diabetic macular edema

OBJECTIVE

The aim of this study is to describe the results of pars plana vitrectomy (PPV) for refractory diabetic macular edema (DME).

METHODS

Review of the relevant peer-reviewed scientific literature identified using Medline.

MAIN OUTCOME MEASURES

The anatomical and functional outcome of surgery.

RESULTS

Vitrectomy with or without internal limiting membrane (ILM) peeling can be beneficial for the treatment of DME that is resistant to laser photocoagulation or sub-Tenon's steroid injection. Visual improvement has been reported in approximately 40-90% of patients, with approximately 85-100% experiencing either improvement or stabilization of vision. Retinal edema decreases or resolves in approximately 70-100% of patients. Complications range in severity with approximately 5-20% of patients developing peripheral retinal breaks, approximately 1-2% developing retinal detachment, approximately 2% developing macular hole, and approximately 10-60% developing cataract. Severe complications such as rubeosis iridis and the fibrinoid syndrome have also been reported.

CONCLUSION

Pars plana vitrectomy can be an effective treatment for diabetic macular edema refractory to laser therapy and/or sub-Tenon's capsule steroid injection.

Vitrectomy for diabetic macular edema: effect of glycemic control (HbA(1c)), renal function (creatinine) and other local factors

AIMS

To determine the effect of preoperative factors on the foveal thickness following vitrectomy for diabetic macular edema.

METHODS

Fifty-eight eyes of 47 patients underwent vitrectomy for diabetic macular edema. In all eyes, no clear, visible vitreomacular traction was present. Twelve eyes were pseudophakic before vitrectomy, and 31 eyes underwent concurrent phacoemulsification and intraocular lens (IOL) implantation. Multiple logistic regression analysis was used to assess the independent effect of age, history of photocoagulation, diabetic retinopathy status, preoperative posterior vitreous detachment, HbA(1c) and serum creatinine levels within 2 weeks before surgery, lens status after surgery and follow-up period on the foveal thickness determined by optical coherence tomography.

RESULTS

The median preoperative visual acuity was 20/100 (range from 20/500 to 20/20), and the median postoperative visual acuity was 20/70 (range from 20/500 to 20/13). The preoperative visual acuity (logarithm of minimal angle of resolution; logMAR) was 0.73 +/- 0.36 (mean +/- SD; 20/107 Snellen acuity), and the mean postoperative logMAR visual acuity was 0.60 +/- 0.39 (20/80), which was significantly better than the mean preoperative value (Wilcoxon signed rank test, p = 0.011). The mean +/- SD of preoperative foveal thickness was 475.9 +/- 172.5 micrometer, and the mean postoperative foveal thickness was 277.3 +/- 171.9 micrometer. The mean postoperative foveal thickness was significantly thinner than the preoperative thickness (Student's paired t test, p < 0.0001). Multiple logistic regression analysis showed that a preoperative low HbA(1c) and postoperative pseudophakia were independently associated with the decrease in foveal thickness (p = 0.01, p = 0.04, respectively).

CONCLUSIONS

The greater reduction in foveal thickness in eyes with an IOL probably resulted from a relatively larger amount of vitreous being removed during the vitrectomy. Because the decrease in foveal thickness may be related to the preoperative glycemic control and the amount of vitreous, these factors should be considered in the planning for vitrectomy.

Resolution of diabetic cystoid macular edema associated with spontaneous vitreofoveal separation

PURPOSE

To report spontaneous resolution of diabetic cystoid macular edema (CME) associated with spontaneous vitreofoveal separation.

DESIGN

Interventional case series.

METHODS

Optical coherence tomography (OCT) was performed on three eyes of three diabetic patients with CME before and after vitreofoveal separation.

RESULTS

In all three eyes, OCT showed cystic changes at the fovea with a slightly detached posterior hyaloid, which remained attached to the optic disk and the fovea. After spontaneous separation of the hyaloid at the fovea, there was resolution of the cystic cavities and restoration of the foveal depression.

CONCLUSIONS

In some eyes of diabetic patients, CME is caused by a vitreous traction. Resolution of CME may occur after spontaneous vitreofoveal separation.

Increased levels of vascular endothelial growth factor and interleukin-6 in the aqueous humor of diabetics with macular edema

PURPOSE

To investigate the relationship between diabetic macular edema and the levels of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in aqueous humor and plasma.

DESIGN

Comparative cross-sectional study.

METHODS

Fifty-four eyes from 54 diabetic patients were used. The concentrations of VEGF and IL-6 in undiluted aqueous specimens (obtained from the eyes during cataract surgery) and in plasma were measured by an enzyme-linked immunosorbent assay. To assess blood-aqueous barrier function, the aqueous flare intensity was measured by a laser flare-cell meter as an estimate of the aqueous protein level.

RESULTS

The aqueous levels of VEGF and IL-6 were significantly correlated with the severity of macular edema (rho = 0.628, P <.001 and rho = 0.517, P <.01, respectively), as well as with the aqueous protein concentration (rho = 0.618, P <.001 and rho = 0.588, P <.001, respectively). Aqueous levels of VEGF and IL-6 were significantly higher than their respective plasma levels (both P <.001). In addition, the aqueous level of VEGF was significantly correlated with that of IL-6 (rho = 0.537, P <.01). Furthermore, the status of the posterior vitreous significantly correlated with the severity of macular edema (rho = 0.618, P <.0001).

CONCLUSIONS

These results suggest that both VEGF and IL-6 are produced together in the intraocular tissues, and are involved in the pathogenesis of macular edema.