Diabetic macular edema: an OCT-based classification

[SERV clinical practice guidelines: management of retinal vein occlusion. Sociedad Española de Retina y Vitreo]

PURPOSE

A guidelines for the management of retinal vein occlusion is presented. This is necessary because at this moment several therapeutic alternatives have been developed although their role is not yet sufficiently defined.

METHODS

Review of the literature for evidence published up to date. Relevant literature was identified and the level of evidence graded. Evidence was then assessed for consistency, applicability and clinical impact. The information was contrasted with those guides published in other countries.

RESULTS

Taking into account the different options of treatment that are currently used, several modes of action are suggested. The role of the various complementary examinations are discussed and it is recommended that criteria for the treatment are based on clinical, angiographic, and tomographic findings.

CONCLUSIONS

Although there is no overall consensus, these guidelines promote a good standard of clinical practise and provide an update of the management of retinal vein occlusion.

Optical coherence tomography imaging for diabetic retinopathy and macular edema

Optical coherence tomography (OCT) is a noninvasive imaging modality that uses low-coherent interferometry to visualize an optical cross-section of biological tissues. Over the past two decades, the ability to perform OCT imaging of the neural retina has afforded clinicians and researchers a highly reproducible method of diagnosing and following diabetic macular edema (DME) that compares favorably to other methods of DME assessment such as clinical examination and fundus photography. Although central subfield mean thickness has been the OCT parameter most commonly used to evaluate DME in clinical research trials, OCT also allows evaluation of morphologic changes that occur in DME, including compact retinal thickening, intraretinal cystic changes, subretinal fluid, and vitreomacular traction. OCT parameters have been shown to be only moderately correlated with visual acuity. However, improvements in technology leading to higher resolution, faster acquisition speed, image registration, and three-dimensional imaging that are available with newer spectral domain OCT models may allow future identification of valid OCT-derived surrogate markers for visual function in patients with diabetes.

Pretreatment clinical variables associated with the response to intravitreal bevacizumab (Avastin) injection in patients with persistent diabetic macular edema

BACKGROUND

The purpose of the study is to determine whether the pre-treatment clinical systemic variables and optical coherence tomography (OCT) findings are associated with the subsequent response to the intravitreal bevacizumab (IVB) in eyes with persistent diabetic macular edema (DME).

DESIGN

Prospective, interventional non-comparative case series study.

METHODS

38 Patients (45 eyes) with refractory diabetic macular edema; 16 females, 22 males with a mean aged 57.5 year. All patients had persistent DME not responded to other forms of treatments. Complete eye examination; best corrected visual acuity (BCVA) (represented as LOGMAR for adequate statistical analysis), slit-lamp exam, intraocular pressure measurement, stereoscopic biomicroscopy of the macula, and morphologic patterns of diabetic macular edema demonstrated by OCT. All patients had intravitreal injection of 0.05 mL = 1.25 mg bevacizumab (Avastin; Genentech, Inc., San Francisco, CA), and were followed up for 3 months. The pre and post-injection follow-up data were analyzed by Student-t test and Mann-Whitney test for two main outcome measures; visual acuity (LOGMAR) and central foveal thickness (CFT) changes over a period of three months, and the data included demographic factors, type, duration and the control of diabetes mellitus (HbA1C%), grade of diabetic retinopathy, renal function (serum creatinine level), serum cholesterol, blood pressure control and previous treatment by focal laser and/or intravitreal triamcinolone injection.

RESULTS

The LOGMAR and central foveal thickness (CRT) improved in 30/45 eyes (67%) and 32/45 eyes (72%), respectively during a mean follow-up time of three months. The mean LOGMAR visual acuities were 0.64 (SD ± 0.34), 0.61 (SD ± 0.31) and 0.60 (SD ± 0.32) at pre-injection, at 1 month post-injection and at 3 months post-injection, respectively; but this mean increase in vision was statistically not significant (P value = 0.099). The mean foveal thicknesses were 444.95 μm (SD ± 127.36), 394.95 μm (SD ± 138.03) and 378.32 μm (SD ± 112.01) at pre-injection, 1 month post-injection and 3 months post-injection, respectively, this decrease in the foveal thickness was statistically significant (P value <0.001). The pre and post-injections values of the variables for diabetic duration, diabetic control (HbA1c) and OCT pattern of macular edema showed significant statistical correlations (P < 0.05) with LOGMAR only, however the values of the variables for serum creatinine and cholesterol show statistical correlation (P < 0.05) with both LOGMAR and CFT.

CONCLUSIONS

Chronicity and inadequate control of diabetes mellitus, nephropathy, hyperlipidemia and presence of vitreomacular attachment (VMA) are factors associated with poor vision progress after intravitreal bevacizumab injection.

Assessment of serous macular detachment in eyes with diabetic macular edema by use of spectral-domain optical coherence tomography

BACKGROUND

The introduction of optical coherence tomography (OCT) has brought new potentialities for an objective evaluation of macular diseases. The purpose of the present study was to assess the serous macular detachment (SMD) in eyes with diabetic macular edema (DME) by use of spectral-domain OCT.

METHODS

In this prospective study were included 79 eyes of 46 patients with diabetic retinopathy and DME. All patients underwent examination of best-corrected visual acuity (BCVA), non-contact slit-lamp fundus biomicroscopy, fluorescein angiography and OCT. Spectral-domain OCT (OCT/SLO Combination Imaging System, OPKO/OT Inc., Toronto, Ontario, Canada) was used to evaluate retinal morphology and the presence of macular traction (vitreomacular and/or from epiretinal membranes) on B-scans, C-scans and C-scan OCT/SLO fundus image overlays. With OCT were measured retinal thickness, volume, diameter of intraretinal cystoid spaces, diameter and height of SMD. The correlation of retinal thickness and volume with BCVA in all eyes with DME and the relation of SMD to retinal thickness, volume, BCVA, macular traction and ischemia were assessed.

RESULTS

The SMD was diagnosed only by means of OCT in nine eyes (11.4%) of five patients. In eight of nine eyes it was combined with intermediate (300-600 microm) or severe (>600 microm) cystoid spaces, and in one eye with simple macular edema. Retinal thickness and volume correlated with BCVA (r = 0.464, P < 0.0001 and r = 0.480, P < 0.0001). The SMD height did not correlate with retinal thickness, volume or BCVA. Six eyes with SMD had macular ischemia, and five eyes had severe ischemia in retinal periphery. Macular traction was: absent in three eyes, questionable (without distortion of retinal contour from partial posterior vitreous detachment and/or epiretinal membrane) in three eyes, and definite (with distortion of retinal contour) in three eyes.

CONCLUSIONS

Spectral-domain OCT provided valuable information on retinal morphology and was particularly useful in diagnosing sub-clinical SMD in eyes with DME. It disclosed the presence and strength of macular traction either by partially detached posterior hyaloid or by epiretinal membranes. C-scans and C-scan OCT/SLO fundus image overlays added complementary information for the extent and location of the pathological features. Larger studies which follow subjects longitudinally are needed to explain the pathogenesis and determine the prognosis of SMD.

Optical Coherence Tomography Use in Evaluation of the Vitreoretinal Interface: A Review

Optical coherence tomography (OCT) is a valuable tool for assessment of the vitreoretinal interface. This article reviews the normal process of age-related posterior vitreous detachment as viewed by OCT. Abnormalities of the vitreoretinal interface as imaged by OCT are described including vitreomacular traction syndrome, cystoid macular edema/ diabetic macular edema, epiretinal membranes, full thickness macular holes, lamellar holes, pseudoholes, microholes, and schisis from myopia or optic pits/colobomas. This tool has given us new insights into the pathogenesis of these retinal abnormalities.

Enhanced optical coherence patterns of diabetic macular oedema and their correlation with the pathophysiology

PURPOSE

To describe different patterns of diabetic macular oedema (DMO) using a computerized alignment and averaging of sequences in optical coherence tomography (OCT) B-scans and to show the correlation of these patterns with the pathophysiology of the condition.

METHODS

We carried out a prospective, uncontrolled study, including 46 human subjects with untreated DMO. Enhanced OCT images were produced. We correlated different OCT patterns of DMO with ETDRS visual acuity and with the thickness of the central 1-mm of the macula. We also correlated these patterns with theories of the pathophysiology of DMO.

RESULTS

Enhanced OCT images enabled us to examine how different layers of the macula were affected. The external limiting membrane (ELM) was clearly seen in all stages, including advanced stages. The sequence of DMO events in different macular layers can be divided into five patterns. Morphologically, DMO starts at the outer nuclear layer/Henle's layer. As the oedema progresses, cysts are seen in the fovea and the DMO spreads further into the inner nuclear layer. The ELM seems to act as a barrier for proteins and plays an important role in the development of DMO.

CONCLUSIONS

Enhanced OCT revealed new details of DMO pathophysiology. The different morphological patterns of DMO seen in enhanced OCT may represent different levels of severity of the disease.

Decreasing efficacy of repeated intravitreal triamcinolone injections in diabetic macular oedema

BACKGROUND/AIM

Intravitreal triamcinolone (IVTA) results in transient improvements in diabetic macular oedema (DMO), necessitating repeated injections. The authors report a case series of 10 eyes of 10 patients with DMO, who received a repeat injection of 4 mg IVTA, at least 26 weeks after the first injection of the same dose.

METHOD

Pre-injection and at 2, 4, 9, and 17 weeks post-injection, best corrected visual acuity (BCVA) and central foveal thickness (CFT) on optical coherence tomography, after the first and repeat injections, were compared using paired t test. Side effects were monitored.

RESULTS

BCVA, CFT, intraocular pressure (IOP), and cataract scores were not significantly different before initial and repeat injections (given at 32.5 (SD 3.5) weeks after the first injection). Transient improvements of BCVA and CFT were achieved after both injections. However, after the repeat injection, the BCVA was significantly worse at all time points (p<0.05) and so were the best achieved CFT and the CFT at 4 weeks post-injection (p = 0.034 and 0.011 respectively), compared with the initial injection. Post-injection maximum IOPs and increase in cataract scores were not significantly different between the two injections.

CONCLUSION

A repeat injection of 4 mg of IVTA may not be as effective as an initial injection for the treatment of DMO.