CHANGES IN SUBFOVEAL CHOROIDAL THICKNESS AFTER INTRAVITREAL DEXAMETHASONE IMPLANT THERAPY FOR DIABETIC MACULAR EDEMA

Optical coherence tomography in the management of diabetic macular oedema

Diabetic macular oedema (DMO) is the major cause of visual impairment in people with diabetes. Optical coherence tomography (OCT) is now the most widely used modality to assess presence and severity of DMO. DMO is currently broadly classified based on the involvement to the central 1 mm of the macula into non-centre or centre involved DMO (CI-DMO) and DMO can occur with or without visual acuity (VA) loss. This classification forms the basis of management strategies of DMO. Despite years of research on quantitative and qualitative DMO related features assessed by OCT, these do not fully inform physicians of the prognosis and severity of DMO relative to visual function. Having said that, recent research on novel OCT biomarkers development and re-defined classification of DMO show better correlation with visual function and treatment response. This review summarises the current evidence of the association of OCT biomarkers in DMO management and its potential clinical importance in predicting VA and anatomical treatment response. The review also discusses some future directions in this field, such as the use of artificial intelligence to quantify and monitor OCT biomarkers and retinal fluid and identify phenotypes of DMO, and the need for standardisation and classification of OCT biomarkers to use in future clinical trials and clinical practice settings as prognostic markers and secondary treatment outcome measures in the management of DMO.

Prognostic value of choroidal vascular index in determining response to intravitreal dexamethasone implant treatment used in refractory diabetic macular edema

To investigate the effect of intravitreal dexamethasone (IVD) implant injection, which was used in the treatment of DME, on CVI and to investigate whether CVI can be used as a prognostic marker in the treatment of anti-VEGF resistant DME. A retrospective observational and comparative study. Twenty-five eyes of 25 patients with refractory diabetic macular edema who underwent intravitreal dexamethasone (IVD) implant and 50 eyes of 50 healthy patients were included in the study. Central macular thickness (CMT), subfoveal choroidal thickness (SFCT), luminal choroidal area (LCA), total choroidal area (TCA), stromal choroidal area (SCA), and choroidal vascularity index (CVI) were measured on optical coherence tomography. There was no significant difference between the groups in terms of age and gender. When the pre-treatment values in the IVD group were compared with the healthy group, LCA and SCA values were higher, and CVI ratios were lower in the IVD group compared to the control group. When baseline, 1st, and 3rd months after injection were compared, it was determined that there was a significant decrease in CMT and LCA. There was no statistically significant difference in SFCT, TCA, and CVI. There was a significant negative correlation between baseline CVI and 3rd month CMT after IVD (rho: - 0.643, p: 0.001). It was observed that the baseline and 1st month LCA values were significantly higher than the 3rd month. The choroidal vascular structure may be affected by IVD treatment. CVI may also have value as a prognostic marker in monitoring the response to treatment.

The Role of Intravitreal Corticosteroids in the Treatment of DME: Predictive OCT Biomarkers

This work aims to summarize predictive biomarkers to guide treatment choice in DME. Intravitreal anti-VEGF is considered the gold standard treatment for centers involving DME, while intravitreal steroid treatment has been established as a second-line treatment in DME. However, more than 1/3 of the patients do not adequately respond to anti-VEGF treatment despite up to 4-weekly injections. Not surprisingly, insufficient response to anti-VEGF therapy has been linked to low-normal VEGF levels in the serum and aqueous humor. These patients may well benefit from an early switch to intravitreal steroid treatment. In these patients, morphological biomarkers visible in OCT may predict treatment response and guide treatment decisions. Namely, the presence of a large amount of retinal and choroidal hyperreflective foci, disruption of the outer retinal layers and other signs of chronicity such as intraretinal cysts extending into the outer retina and a lower choroidal vascular index are all signs suggestive of a favorable treatment response of steroids compared to anti-VEGF. This paper summarizes predictive biomarkers in DME in order to assist individual treatment decisions in DME. These markers will help to identify DME patients who may benefit from primary dexamethasone treatment or an early switch.

Choroidal Structural Changes of Posterior Subtenon Triamcinolone Acetonide Injection in Eyes with Refractory Diabetic Macular Edema

Purpose

To access the choroidal structural changes of posterior subtenon triamcinolone acetonide (PSTA) injection in eyes with refractory diabetic macular edema (DME).

Methods

Patients with refractory DME were enrolled and followed for 4 weeks after switching to PSTA injection. All patients underwent spectral-domain optical coherence tomography with enhanced depth imaging, and the choroidal images were binarized into the luminal area and total choroidal area. Subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) were evaluated before and after switching treatments.

Results

After switching to PSTA treatment, the final best-corrected visual acuity and central subfield thickness in eyes with refractory DME were significantly improved compared to the baseline values (P=0.002 and P < 0.001, respectively). Both the SFCT and CVI decreased during the follow-up period, and significant decreases were observed at 4-week follow-up (P < 0.001 and P=0.012, respectively). The linear regression analysis showed a significant correlation between the baseline SFCT and the final visual outcomes (P=0.047).

Conclusions

The alterations of SFCT and CVI in this study suggest that the choroidal vasculature is involved in the pathogenesis of refractory DME and could be affected by PSTA treatment. SFCT rather than CVI may be a prognostic biomarker for eyes with refractory DME.