Impact of Bleaching on Photoreceptors in Different Intermediate AMD Phenotypes

Micropulse Laser versus Eplerenone for Chronic Central Serous Chorioretinopathy: A 12-Month Comparison

INTRODUCTION

To compare the long-term efficacy of navigated subthreshold micropulse laser (NSML) and continuous oral eplerenone (EPL) in chronic central serous chorioretinopathy (cCSC).

METHODS

This retrospective observational study included 44 eyes with cCSC (EPL: n = 26; NSML: n = 18). Best-corrected visual acuity (BCVA), central macular thickness (CMT), subretinal fluid (SRF) height, and subfoveal choroidal thickness (SFCT) were evaluated over 12 months.

RESULTS

Both groups showed significant improvements in BCVA and CMT (p < 0.05). Complete SRF resolution was achieved in both groups by 12 months, with NSML showing faster resolution (2.77 ± 1.43 vs. 6.34 ± 2.17 months, p < 0.001). The EPL group demonstrated significant SFCT reduction at 6 and 12 months (p = 0.001), while the NSML group showed no significant SFCT changes (p > 0.05).

CONCLUSIONS

Both NSML and EPL improved retinal morphology and visual function in patients with cCSC. NSML achieved faster SRF resolution, while EPL resulted in more significant choroidal thickness reduction. These findings suggest distinct mechanisms of action: NSML primarily affects the retinal pigment epithelium, while EPL modulates choroidal vasculature. Treatment choice may depend on individual patient characteristics and treatment goals.

OCT risk factors for 2-year foveal involvement in non-treated eyes with extrafoveal geographic atrophy and AMD

PURPOSE

To assess the relationship of optical coherence tomography (OCT) findings and progression to foveal atrophy in a cohort of eyes with extrafoveal geographic atrophy (GA) and age-related macular degeneration (AMD) at inclusion.

METHODS

We retrospectively analyzed 45 participants (45 eyes) with extrafoveal GA at baseline and with 2 years of regular follow-ups. Several OCT qualitative features (i.e., presence of foveal flat pigment epithelium detachment with a thin double layer sign [DLS] and reticular pseudodrusen, GA focality) and quantitative measurements (outer retinal layer thickness, retinal pigment epithelium [RPE] to Bruch's membrane [BM] volume, minimum distance from the central foveal circle, and untransformed GA lesion size area) were assessed at baseline. Logistic regression analyses were carried out to identify independent significant predictors and compute odds ratios (ORs) for the risk of the development of atrophy.

RESULTS

At month 24, 26 eyes (57.8%) developed atrophy in the foveal central circle, while 11 eyes (24.4%) developed atrophy in the foveal central point. Significant independent predictive features for the development of atrophy in the foveal central circle included foveal outer retinal thickness (OR, 0.867; p = 0.015), minimum distance from the foveal central circle (OR, 0.992; p = 0.022), and foveal thin DLS (OR, 0.044; p = 0.036). The only independent predictive feature for the development of atrophy in the foveal central point was the presence of foveal thin DLS (OR, 0.138; p = 0.017).

CONCLUSIONS

We identified OCT risk factors for 2-year foveal atrophy in eyes with untreated extrafoveal GA at baseline.

Retinal neurodegeneration in age-related macular degeneration

Age-related macular degeneration (AMD) is a complex and multifactorial disease characterized by the damage of the unit comprised of the photoreceptors, retinal pigment epithelium (RPE), Bruch's membrane, and choriocapillaris. Although the outer retina appears to be mainly affected in this disorder, several evidences exhibit that also the inner retina may be impaired. In this review we will provide a description of the prominent histologic and imaging findings suggesting an inner retinal loss in these eyes. In details, structural optical coherence tomography (OCT) technology proved either the inner and outer retina is impacted by AMD and that these two impairments are associated. Therefore, the purpose of this review is to provide a description of the role of neurodegeneration in AMD in order to better understand the relationship between neuronal loss and the outer retinal damage in this disease.

The Impact of Photopigment Bleaching on the Human Rod Photoreceptor Subretinal Space Measured Via Optical Coherence Tomography

Purpose

The purpose of this study was to investigate rod photopigment bleaching-driven intrinsic optical signals (IOS) in the human outer retina and its measurement repeatability based on a commercial optical coherence tomography (OCT) platform.

Methods

The optical path length of the rod photoreceptor subretinal space (SRS), that is, the distance between signal bands of rod outer segment tips and retinal pigment epithelium, was measured in 15 healthy subjects in ambient light and during a long-duration bleaching white-light exposure.

Results

On 2 identical study days (day 1 and day 2 [D1 and D2]), light stimulation resulted in a significant decrease in rod SRS by 21.3 ± 7.6% and 19.8 ± 8.5% (both P < 0.001), respectively. The test-retest reliability of the SRS maximum change of an individual subject was moderate for single measures (intraclass correlation coefficient [ICC] = 0.730, 95% confidence interval [CI] = 0.376, 0.900, P < 0.001) and good for average measures (ICC = 0.844, 95% CI = 0.546, 0.947, P < 0.001). The mean area under the stimulus response curve with values of 14.8 ± 9.4 and 15.5 ± 7.5 µm × minutes (P = 0.782) showed excellent agreement between the stimulus response on D1 and D2. Intermittent dark adaptation of the retina led to an initial increase of the SRS by 6.1% (P = 0.018) and thereafter showed a decrease toward baseline, despite continued dark adaptation.

Conclusions

The data indicate the potential of commercial OCT in measuring slow IOS in the outer retina suggesting that the rod SRS could serve as a biomarker for photoreceptor function. The presented approach could provide an easily implementable clinical tool for the early detection of diseases affecting photoreceptor health.

The retina-brain axis and diabetic retinopathy

Diabetic retinopathy (DR) is a major contributor to permanent vision loss and blindness. Changes in retinal neurons, glia, and microvasculature have been the focus of intensive study in the quest to better understand DR. However, the impact of diabetes on the rest of the visual system has received less attention. There are reports of associations of changes in the visual system with preclinical and clinical manifestations of diabetes. Simultaneous investigation of the retina and the brain may shed light on the mechanisms underlying neurodegeneration in diabetics. Additionally, investigating the links between DR and other neurodegenerative disorders of the brain including Alzheimer's and Parkinson's disease may reveal shared mechanisms for neurodegeneration and potential therapy options.

Short-term peripapillary structural and vascular changes following anti-VEGF vs. Dexamethasone intravitreal therapy in patients with DME

PURPOSE

To evaluate short-term peripapillary structural and vascular changes in DME after treatment with dexamethasone implant (DEX-I) and anti-VEGFs using OCT-A.

METHODS

Sixty-five patients with naïve center-involving DME were enrolled. 33 of sixty five patients (group 1) underwent with single DEX-I 0.7 mg (Ozurdex, Allergan, Inc., USA), 32 of sixty-five (group 2) underwent with intravitreal injection of aflibercept 0.5 mg (Eylea, Bayer, Genentech, San Francisco, USA). The OCT acquisition was completed at the following visits: (i) "T1 visit" corresponding to the intravitreal injection of DEX-I or aflibercept in patients with naïve center-involving DME (ii) "T2 visit" corresponding to the examination performed 2 weeks after intravitreal injection of aflibercept and 1 month after DEX-I. The parameters analyzed were: (i) RPC vasculature density (VD); (ii) peripapillary retinal nerve fiber layer (pRNFL) thickness, and (iii) intraocular pressure (IOP).

RESULTS

The RPC analysis showed a VD increase at T2 in both groups, although values did not reach statistical significance (48.12± 4.17 and 49.04 ± 4.23; P = 0.081 in Group 1 and 46.93± 3.16 and 47.17 ± 3.70; P = 0.087 in Group 2). Likewise, the pRNFL thickness and IOP fluctuations did not show statistically significant changes in in both groups among the different study visits.

CONCLUSIONS

After intravitreal injection (anti-VEGF or DEX-I), no significant short-term changes were found in peripapillary microvasculature, IOP and pRNFL thickness in diabetic eyes treated with anti-VEGF or DEX-I.

Effects of diabetic retinopathy on longitudinal morphological changes in AMD-associated type 1 macular neovascularization

The purpose of this study was to investigate the effect of diabetic retinopathy (DR) on longitudinal morphological changes in AMD-associated type 1 macular neovascularization using optical coherence tomography angiography (OCTA). We enrolled fifty treatment-naïve eyes with a diagnosis of exudative AMD and type 1 MNV. Twenty of 50 eyes were affected by mild DR. En face OCT angiography were examined for the MNV lesion area (mm2), the MNV flow area (mm2), the central macular thickness (CMT) and the BCVA. The OCTA acquisition was performed at the following visits: (i) before the loading phase (LP) of intravitreal injection of aflibercept (T1), and (ii) 1 month after the last intravitreal injection of loading phase comprising 3 monthly injections (T2). All morpho-functional parameters showed a significantly change at T2 compared to T1 values in both groups. Furthermore, we found a greater MNV area reduction after LP in eyes without DR (P = 0.023). With regard to the remaining parameters, no significant changes were found between two groups (P > 0.05). Our analysis revealed a less MNV area reduction after loading dose of anti-VEGF therapy in eyes affected by diabetic retinopathy.

Yellow Subthreshold Micropulse Laser in Retinal Diseases: An In-Depth Analysis and Review of the Literature

Yellow subthreshold micropulse laser (YSML) is a retinal laser capable of inducing a biologic response without causing thermal damage to the targeted tissue. The 577-nm YSML is delivered to the retina abiding by different protocols in which wavelength, power, duration, spot size and number of spots can be properly set to achieve the most effective and safe treatment response in various chorioretinal disorders. The ultrashort trains of power modulate the activation of the retinal pigment epithelium cells and intraretinal cells, such as Müller cells, causing no visible retinal scars. Subthreshold energy delivered by YSML stimulates the production of the heat-shock proteins, highly conserved molecules that protect cells against any sort of stress by blocking apoptotic and inflammatory pathways that cause cell damage. YSML treatment allows resorption of the subretinal fluid in central serous chorioretinopathy and intraretinal fluid in various conditions including diabetic macular edema, postoperative cystoid macular edema and other miscellaneous conditions. YSML also seems to modulate the development and progression of reticular pseudodrusen in dry age-related macular degeneration. The aim of this review is to discuss and summarize the safety and efficacy of YSML treatment in retinal diseases.

Optical coherence tomography in healthy human subjects in the setting of prolonged dark adaptation

Human studies have established that short periods of dark adaptation can induce outer retinal thinning and various band intensity changes that can be detected with Optical Coherence Tomography (OCT). Similar findings were observed in mice, including a positive correlation between the degree of outer retinal changes and dark adaptation duration. We decided to assess potential retinal structural changes following prolonged dark adaptation in humans. 40 healthy subjects without any ocular diseases participated in this study. For each subject, one eye was covered for dark adaptation for four hours, and the other eye was left uncovered as a control. Before and after the dark adaptation period, both eyes were assessed with OCT. Using the Heidelberg Spectralis system, basic statistical functions, and qualitative and quantitative analysis, we were able to compare retinal layer thicknesses and band intensities between covered (dark adapted) versus uncovered (control) eyes. Prolonged dark adaptation did not induce any significant thickness, volume, or intensity changes in the outer retina or in the inner or overall retina. These observations thus alter our current understanding of the mechanisms underlying dark adaptation's neuroprotective effects in preventing blindness and require further study.

Choroidal structural changes in different intermediate AMD patterns

PURPOSE

To report variation of choroidal thickness (CT) and choroidal vascularity index (CVI) in subjects with drusen and subjects with reticular pseudodrusen (RPD) compared with healthy individuals using the Spectral-domain (SD)-Optical Coherence Tomography with enhanced depth imaging (EDI) system.

DESIGN

A prospective, observational, cross-sectional study.

SUBJECTS

Eighty-four participants.

METHODS

The patients were imaged using the Heidelberg Spectralis device (Heidelberg Engineering, Heidelberg, Germany) with EDI mode. EDI-OCT images were exported and then imported into image analysis ImageJ software (National Institutes of Health, Bethesda) and a semiautomated algorithm was used for subsequent quantitative analysis.

MAIN OUTCOME MEASURES

This study evaluated two choroidal parameters: (i) choroidal thickness (CT); (ii) choroidal vascularity index (CVI).

RESULTS

CT analysis was performed in three different regions: (i) foveal region, (ii) parafoveal region; (iii) perifoveal region. All the analyzed regions were significantly decreased in RPD pattern, as compared with both the drusen group (p < .005) and healthy eyes (p < .005). CVI was significantly decreased in the RPD pattern, as compared with healthy eyes (p < 0.001). However, the drusenoid pattern did not have statistical significance in comparison with the control group suggesting the lower incidence of this pattern on choroidal vasculopathy.

CONCLUSIONS

We report CT and CVI difference in RPD and drusen eyes. The RPD pattern seems to be a consequence of an alteration in the choroidal vascularity resulting in severe ischemia and excessive hypoxia inducing an increased risk of late AMD compared to the drusenoid pattern.

Subthreshold laser treatment for reticular pseudodrusen secondary to age-related macular degeneration

There is a lack of treatment aimed at the regression of reticular pseudodrusen (RPD) secondary to age-related macular degeneration (AMD). The aim of this prospective, pilot study is to evaluate the safety and short-term efficacy of subthreshold laser treatment (SLT) in patients affected by RPD secondary to dry AMD (dAMD). Twenty eyes of 20 patients (mean age 78.4 ± 6.8 years) with RPD secondary to dAMD were prospectively enrolled. All patients were treated in an extrafoveal area of 1.27 mm² using end-point management yellow subthreshold laser and followed for 3 months. Best-corrected visual acuity was 0.140 ± 0.09 LogMAR at the baseline and no changes were observed during the follow-up (p = 0.232). No significant worsening was disclosed before and after the treatment analyzing the macular sensitivity of the treated area (p = 0.152). No topical and/or systemic side effects were disclosed during the 3-month follow-up. The distribution among the RPD stages changed after the treatment (p < 0.001). In detail, in the treated area, we observed a significant increase in the number of Stage 1 RPD during the follow-up (p = 0.002), associated with a significant decrease of Stage 3 RPD (p = 0.020). Outer nuclear layer (ONL) thickness analysis showed a significant increase after the treatment associated with RPD regression (p = 0.001). End-point management SLT appears a safe treatment for RPD secondary to dAMD, showing short-term safety outcomes. Our results suggest that SLT could be effective in inducing a RPD regression in terms of RPD stage and ONL thickening.

Reviewing the Role of Ultra-Widefield Imaging in Inherited Retinal Dystrophies

Inherited retinal dystrophies (IRD) are a heterogeneous group of rare chronic disorders caused by genetically determined degeneration of photoreceptors and retinal pigment epithelium cells. Ultra-widefield (UWF) imaging is a useful diagnostic tool for evaluating retinal integrity in IRD, including Stargardt disease, retinitis pigmentosa, cone dystrophies, and Best vitelliform dystrophy. Color or pseudocolor and fundus autofluorescence images obtained with UWF provide previously unavailable information on the retinal periphery, which correlates well with visual field measurement or electroretinogram. Despite unavoidable artifacts of the UWF device, the feasibility of investigations in infants and in patients with poor fixation makes UWF imaging a precious resource in the diagnostic armamentarium for IRD.