Oral Dextromethorphan for the Treatment of Diabetic Macular Edema: Results From a Phase I/II Clinical Study

Influence of OCT biomarkers on microperimetry intra- and interdevice repeatability in diabetic macular edema

To evaluate the intra- and interdevice repeatability of microperimetry (MP) assessments in patients with diabetic macular edema (DME) two consecutive MP testings (45 fovea-centered stimuli, 4-2 staircase strategy) were performed using MP3 (NIDEK, Aichi, Japan) and MAIA (CenterVue, Padova, Italy), respectively. Intraretinal fluid (IRF) and ellipsoid zone (EZ) thickness were automatically segmented by published deep learning algorithms. Hard exudates (HEs) were annotated semi-automatically and disorganization of retinal inner layers (DRIL) was segmented manually. Point-to-point registration of MP stimuli to corresponding spectral-domain OCT (Spectralis, Heidelberg Engineering, Germany) locations was performed for both devices. Repeatability was assessed overall and in areas of disease-specific OCT biomarkers using Bland-Altmann coefficients of repeatability (CoR). A total of 3600 microperimetry stimuli were tested in 20 eyes with DME. Global CoR was high using both devices (MP3: ± 6.55 dB, MAIA: ± 7.69 dB). Higher retest variances were observed in stimuli with IRF (MP3: CoR ± 7.4 dB vs. ± 6.0 dB, p = 0.001, MAIA: CoR ± 9.2dB vs. ± 6.8 dB, p = 0.002) and DRIL on MP3 (CoR ± 6.9 dB vs. ± 3.2 dB, p < 0.001) compared to stimuli without. Repeatabilities were reduced in areas with thinner EZ layers (both p < 0.05). Fixation (Fuji classification) was relatively unstable independent of device and run. These findings emphasize taking higher caution using MP in patients with DME.

Diabetic Macular Edema: Current Understanding, Molecular Mechanisms and Therapeutic Implications

Diabetic retinopathy (DR), with increasing incidence, is the major cause of vision loss and blindness worldwide in working-age adults. Diabetic macular edema (DME) remains the main cause of vision impairment in diabetic patients, with its pathogenesis still not completely elucidated. Vascular endothelial growth factor (VEGF) plays a pivotal role in the pathogenesis of DR and DME. Currently, intravitreal injection of anti-VEGF agents remains as the first-line therapy in DME treatment due to the superior anatomic and functional outcomes. However, some patients do not respond satisfactorily to anti-VEGF injections. More than 30% patients still exist with persistent DME even after regular intravitreal injection for at least 4 injections within 24 weeks, suggesting other pathogenic factors, beyond VEGF, might contribute to the pathogenesis of DME. Recent advances showed nearly all the retinal cells are involved in DR and DME, including breakdown of blood-retinal barrier (BRB), drainage dysfunction of Müller glia and retinal pigment epithelium (RPE), involvement of inflammation, oxidative stress, and neurodegeneration, all complicating the pathogenesis of DME. The profound understanding of the changes in proteomics and metabolomics helps improve the elucidation of the pathogenesis of DR and DME and leads to the identification of novel targets, biomarkers and potential therapeutic strategies for DME treatment. The present review aimed to summarize the current understanding of DME, the involved molecular mechanisms, and the changes in proteomics and metabolomics, thus to propose the potential therapeutic recommendations for personalized treatment of DME.

Clinical Perspectives and Trends: Microperimetry as a trial endpoint in retinal disease

Endpoint development trials are underway across the spectrum of retinal disease. New validated endpoints are urgently required for the assessment of emerging gene therapies and in preparation for the arrival of novel therapeutics targeting early stages of common sight-threatening conditions such as age-related macular degeneration. Visual function measures are likely to be key candidates in this search. Over the last two decades, microperimetry has been used extensively to characterize functional vision in a wide range of retinal conditions, detecting subtle defects in retinal sensitivity that precede visual acuity loss and tracking disease progression over relatively short periods. Given these appealing features, microperimetry has already been adopted as an endpoint in interventional studies, including multicenter trials, on a modest scale. A review of its use to date shows a concurrent lack of consensus in test strategy and a wealth of innovative disease and treatment-specific metrics which may show promise as clinical trial endpoints. There are practical issues to consider, but these have not held back its popularity and it remains a widely used psychophysical test in research. Endpoint development trials will undoubtedly be key in understanding the validity of microperimetry as a clinical trial endpoint, but existing signs are promising.

ASSESSMENT OF HYPERREFLECTIVE FOCI AFTER BEVACIZUMAB OR DEXAMETHASONE TREATMENT ACCORDING TO DURATION OF MACULAR EDEMA IN PATIENTS WITH BRANCH RETINAL VEIN OCCLUSION

PURPOSE

To evaluate the association between hyperreflective foci (HRF) on spectral domain optical coherence tomography and therapeutic effect of intravitreal bevacizumab (IVB) or intravitreal dexamethasone implants (IVD) according to macular edema (ME) duration in branch retinal vein occlusion.

METHODS

Consecutive treatment-naive patients received IVB or IVD for at least 6 months. Each group was subdivided according to ME duration (<3 months vs. ≥3 months). Hyperreflective foci and best-corrected visual acuity were compared.

RESULTS

Of 139 eyes (139 patients), 69 received IVB and 70 received IVD. At baseline, eyes with ME ≥ 3 months had more outer and total retinal HRF than eyes with ME < 3 months (P < 0.001 and P = 0.001). At 6 months, the IVD group exhibited a greater reduction in outer retinal HRF than the IVB group in both ME duration subgroups (P = 0.015 and P < 0.001). In the ME ≥ 3 months group, IVD resulted in greater best-corrected visual acuity improvement than IVB (P = 0.017).

CONCLUSION

Increased outer retinal HRF at baseline in eyes with ME ≥ 3 months together with a greater reduction in HRF at 6 months and better visual outcomes after IVD suggests that the inflammatory aspect of disease should be considered in the treatment of ME. Thus, IVD injection could be more appropriate for patients with a longer ME duration after branch retinal vein occlusion.