Three-dimensional automated choroidal volume assessment on standard spectral-domain optical coherence tomography and correlation with the level of diabetic macular edema

Effect of intravitreal dexamethasone implant on retinal and choroidal thickness in refractory diabetic macular oedema after multiple anti-VEGF injections

AimsTo investigate the effect of intravitreal dexamethasone implant (IVD) on central foveal thickness (CFT), choroidal thickness (CT) and its correlation with visual acuity in eyes with refractory diabetic macular oedema (DMO).MethodsThis was a retrospective interventional case-series. Thirty-five eyes of 35 patients were treated with a single injection of IVD because of refractory DMO with CFT over 300 μm, and persistent intraretinal and subretinal fluid despite of multiple intravitreal bevacizumab injections. Patients were followed-up for 6 months for the evaluation of CFT and subfoveal CT by spectral-domain optical coherence tomography.ResultsAll eyes (mean age: 59.4±12.35 years; 18 males, 17 females) had been previously treated with multiple bevacizumab injections and showed persistent DMO (mean number of injections 4.08±2.98) The preoperative logMAR BCVA was 0.49±0.24, which gradually improved to 0.46±0.32 at 6 months (P=0.652) and 26% gained two or more lines of Snellen visual acuity. At baseline, the mean CFT was 526.29±123.48 μm, which significantly improved to 316.15±100.09 μm at 3 months (P<0.001). However, CFT deteriorated to 457.07±136.53 μm at 6 months (P=0.051). Similarly, the mean preoperative subfoveal CT was 288.91±36.47 μm and it decreased to 266.85±30.93 μm at 3 months (P<0.01), but increased to 278.63±32.55 μm at 6 months (P=0.137). The reduction of CFT from baseline showed significant correlation with that of subfoveal CT at 3 months (P=0.041) and at 6 months (P=0.008).ConclusionsIn DMO refractory to multiple bevacizumab injections, IVD significantly reduced CFT and subfoveal CT, with BCVA improvement in one-fourth of the patients. The reduction of CFT showed significant correlation with reduction of subfoveal CT.

Choroidal vascularity index as a measure of vascular status of the choroid: Measurements in healthy eyes from a population-based study

The vascularity of the choroid has been implicated in the pathogenesis of various eye diseases. To date, no established quantifiable parameters to estimate vascular status of the choroid exists. Choroidal vascularity index (CVI) may potentially be used to assess vascular status of the choroid. We aimed to establish normative database for CVI and identify factors associated with CVI in healthy eyes. In this population-based study on 345 healthy eyes, choroidal enhanced depth imaging optical coherence tomography scans were segmented by modified image binarization technique. Total subfoveal choroidal area (TCA) was segmented into luminal (LA) and stromal (SA) area. CVI was calculated as the proportion of LA to TCA. Linear regression was used to identify ocular and systemic factors associated with CVI and subfoveal choroidal thickness (SFCT). Subfoveal CVI ranged from 60.07 to 71.27% with a mean value of 65.61 ± 2.33%. CVI was less variable than SFCT (coefficient of variation for CVI was 3.55 vs 40.30 for SFCT). Higher CVI was associated with thicker SFCT, but not associated with most physiological variables. CVI was elucidated as a significant determinant of SFCT. While SFCT was affected by many factors, CVI remained unaffected suggesting CVI to be a more robust marker of choroidal diseases.

Choroidal thickness maps from spectral domain and swept source optical coherence tomography: algorithmic versus ground truth annotation

BACKGROUND/AIMS

The purpose of the study was to create a standardised protocol for choroidal thickness measurements and to determine whether choroidal thickness measurements made on images obtained by spectral domain optical coherence tomography (SD-OCT) and swept source (SS-) OCT from patients with healthy retina are interchangeable when performed manually or with an automatic algorithm.

METHODS

36 grid cell measurements for choroidal thickness for each volumetric scan were obtained, which were measured for SD-OCT and SS-OCT with two methods on 18 eyes of healthy volunteers. Manual segmentation by experienced retinal graders from the Vienna Reading Center and automated segmentation on >6300 images of the choroid from both devices were statistically compared.

RESULTS

Model-based comparison between SD-OCT/SS-OCT showed a systematic difference in choroidal thickness of 16.26±0.725 μm (p<0.001) for manual segmentation and 21.55±0.725 μm (p<0.001) for automated segmentation. Comparison of automated with manual segmentations revealed small differences in thickness of -0.68±0.513 μm (p=0.1833). The correlation coefficients for SD-OCT and SS-OCT measures within eyes were 0.975 for manual segmentation and 0.955 for automatic segmentation.

CONCLUSION

Choroidal thickness measurements of SD-OCT and SS-OCT indicate that these two devices are interchangeable with a trend of choroidal thickness measurements being slightly thicker on SD-OCT with limited clinical relevance. Use of an automated algorithm to segment choroidal thickness was validated in healthy volunteers.

New Diagnostic and Therapeutic Approaches for Preventing the Progression of Diabetic Retinopathy

Diabetic retinopathy (DR) is a severe sight-threatening complication of diabetes mellitus. Retinal laser photocoagulation, antivascular endothelial growth factors, steroid therapy, and pars plana vitrectomy are now used extensively to treat advanced stages of diabetic retinopathy. Currently, diagnostic devices like ultrawide field fundus fluorescein angiography and the improvement of optical coherence tomography have provided quicker and more precise diagnosis of early diabetic retinopathy. Thus, treatment protocols have been modified accordingly. Various types of lasers, including the subthreshold micropulse laser and RPE-targeting laser, and selective targeted photocoagulation may be future alternatives to conventional retinal photocoagulation, with fewer complications. The new developed intravitreal medications and implants have provided more therapeutic options, with promising results.

Evaluation of ocular pulse amplitude and choroidal thickness in diabetic macular edema

PURPOSE

The aim of this study is to evaluate the ocular pulse amplitude (OPA) and choroidal thickness (CT) measurements in patients with diabetic macular edema (DME) and healthy subjects.

METHODS

A total of 34 patients (12 male and 22 female) who had type 2 diabetes mellitus with DME and 34 sex-matched healthy subjects (13 male and 21 female) were included in this prospective study. The intraocular pressure (IOP) and OPA were measured with Dynamic contour tonometer (Pascal DCT, Switzerland). The subfoveal CT was measured using the Cirrus HD-OCT (Carl Zeiss Meditec). The CT at 1500 μm and 3000 μm nasal and temporal to the central fovea was also measured.

RESULTS

The mean IOP values were 18.4±3.5 and 17.1±2.1 mm Hg in DME patients and healthy controls, respectively (P= 0.091). The mean OPA values in patients with DME (2.58±0.96) and controls (3.52±1.03) were statistically different (P<0.001). The mean subfoveal CT value was 273.5±30.2 μm in the eyes with DME and 321.4±36.5 μm in the control group (P< 0.001). In both groups, linear regression analysis showed no significant association between OPA and CT measurements. The IOP showed a significantly positive correlation with OPA in both DME (P=0.002, r=0.526) and controls (P=0.004, r=0.483).

CONCLUSIONS

The current study suggests that both pulsatile choroidal blood flow and CT are decreased in patients with DME.

Investigating the choriocapillaris and choroidal vasculature with new optical coherence tomography technologies

The body of knowledge of in vivo investigation of the choroid has been markedly enhanced by recent technological advances in optical coherence tomography (OCT). New insights elucidating the morphological features of the choriocapillaris and choroidal vasculature, in both physiological and pathological conditions, indicate that the choroid plays a pivotal role in many posterior segment diseases. In this article, a review of the histological characteristics of the choroid, which must be considered for the proper interpretation of in vivo imaging, is followed by a comprehensive discussion of fundamental principles of the current state-of-the-art in OCT, including cross-sectional OCT, en face OCT, and OCT angiography using both spectral domain OCT and swept source OCT technologies. A detailed review of the tomographic features of the choroid in the normal eye is followed by relevant findings in prevalent chorioretinal diseases, focusing on major causes of vision loss such as typical early and advanced age-related macular degeneration, polypoidal choroidal vasculopathy, central serous chorioretinopathy, pachychoroid spectrum disorders, diabetic choroidopathy, and myopia.

Novel approaches for treating diabetic retinopathy based on recent pathogenic evidence

Diabetic retinopathy remains as a leading cause of blindness in developed countries. Current treatments target late stages of DR when vision has already been significantly affected. A better understanding of the pathogenesis of DR would permit the development of more efficient preventional/interventional strategies against early stages of DR. In this article a critical review of the state of the art of this issue is provided along with a discussion of problems which have yet to be overcome. Neuroprotection as a new approach for the treatment of the early stages of DR has been particularly emphasized. The development and progression of DR is not homogeneous and, apart from blood glucose levels and blood pressure, it depends on genetic factors which remain to be elucidated. In addition, the role of the pathogenic pathways is not the same in all patients. All these factors should be taken into account in the near future when an individualized oriented treatment for DR could become feasible. The new techniques in retinal imaging acquisition, the identification of useful circulating biomarkers and the individualized analysis of biological samples could facilitate the development of early and personalized therapy in the setting of DR. Finally, it should be noted that only a coordinated action among ophthalmologists, diabetologists, basic researchers, experts in pharmaco-economics and health care providers addressed to the design of rational strategies targeting prevention and the early stages of DR will be effective in reducing the burden and improving the clinical outcome of this devastating complication of diabetes.