Choroid, Haller's, and Sattler's layer thickness in intermediate age-related macular degeneration with and without fellow neovascular eyes

Choroidal imaging biomarkers as predictors of conversion to exudative age-related macular degeneration

PURPOSE

Predicting the progression of intermediate AMD (iAMD) to neovascular AMD (nAMD) will help to identify high-risk patients and improve treatment outcomes. The present study assessed whether choroidal OCT biomarkers could predict conversion to nAMD.

METHODS

This retrospective study included patients with clinically stable iAMD who either converted to nAMD (C group) or did not convert (NC group) during one year of follow-up. OCT parameters included subfoveal choroidal thickness (SFCT), central macular thickness (CMT), Haller vascular thickness (HVT), inner choroidal thickness (ICT), and double-layer sign (DLS).

RESULTS

Of 116 total eyes, there were 37 in the NC group and 79 in the C group. Baseline SFCT was significantly lower in the C group compared to the NC group (169.0 ± 63.2 μm vs. 218.0 ± 97.8 μm, p = 0.01). Baseline HVT and ICT were lower in the C group (105.2 ± 40.6 μm vs. 121.0 ± 56.6 μm, p = 0.17 and 61.9 ± 35.5 μm vs. 77.5 ± 41.7 μm, p = 0.09). HVT was decreased at all time points in the C group vs NC (p > 0.05). The ICT was reduced in the C group at each time point except at conversion time (p > 0.05). Of all eight eyes who presented DLS at baseline, 100% converted to nAMD (p < 0.001).

CONCLUSION

Lower SFCT at baseline may signal conversion to nAMD within 12 months.

The structure and function of the human choroid

In this manuscript, the structure of the human choroid is reviewed with emphasis of the macro- and microscopic anatomy including Bruch's membrane, choriocapillaris, Sattler's and Haller's layer, and the suprachoroid. We here discuss the development of the choroid, as well as the question of choroidal lymphatics, and further the neuronal control of this tissue, as well as the pathologic angiogenesis. Wherever possible, functional aspects of the various structures are included and reviewed.

Choriocapillaris Flow Signal Impairment in Patients With Pseudoxanthoma Elasticum

Purpose

To quantify choriocapillaris flow alterations in patients with pseudoxanthoma elasticum (PXE) in pre-atrophic stages and its association with structural changes of the choroid and outer retina.

Methods

Thirty-two eyes of 21 patients with PXE and 35 healthy eyes of 35 controls were included. The density of choriocapillaris flow signal deficits (FDs) was quantified on 6 × 6-mm optical coherence tomography angiography (OCTA) images. Spectral-domain optical coherence tomography (SD-OCT) images were analyzed for thicknesses of the choroid and outer retinal microstructure and correlated with choriocapillaris FDs in the respective Early Treatment Diabetic Retinopathy Study subfield.

Results

The multivariable mixed model analysis for choriocapillaris FDs revealed significantly higher FDs associated with the group (PXE patients vs. controls +13.6; 95% confidence interval [CI] 9.87-17.3; P < 0.001), with increasing age (+0.22% per year; 95% CI 0.12-0.33; P < 0.001), and with retinal location (significantly higher FDs in nasal compared to temporal subfields). Choroidal thickness (CT) did not differ significantly between both groups (P = 0.078). The CT and choriocapillaris FDs were inversely correlated (-1.92 µm per %FDs; interquartile range -2.81 to -1.03; P < 0.001). Larger values of the choriocapillaris FDs were associated with significant thinning of the overlying photoreceptor layers (outer segments: -0.21 µm per %FDs, P < 0.001; inner segments: -0.12 µm per %FDs, P = 0.001; outer nuclear layer: -0.72 µm per %FDs; P < 0.001).

Conclusions

Patients with PXE display significant alterations of the choriocapillaris on OCTA even in pre-atrophic stages and in the absence of significant choroidal thinning. The analysis favors choriocapillaris FDs over choroidal thickness as a potential early outcome measure for future interventional trials in PXE. Further, increased FDs in nasal compared to temporal locations mirror the centrifugal spread of Bruch's membrane calcification in PXE.

Retinal and choroidal changes in AMD: A systematic review and meta-analysis of spectral-domain optical coherence tomography studies

Optical coherence tomography is a noninvasive imaging technology using the optical reflectivity of tissues that is capable of detecting quantitative and qualitative biomarkers of age-related macular degeneration (AMD) that cannot be similarly recognized in conventional imaging. We systematically searched PubMed and Embase databases to identify relevant articles to this subject. A fixed-effect or random-effect model was applied for the meta-analysis based on the heterogeneity level. In addition, subgroup analyses, meta-regression, publication bias, and quality assessment were also performed. Twenty-five studies with 1,632 cases and 1,445 healthy controls in total were included. Our results revealed that, when compared to controls, AMD subjects showed a significantly lower thickness in the choroid at 500 µm temporal, 1,500 µm nasal, and temporal to the fovea, subfoveal choroid, average peripapillary retinal nerve fiber layer, and average macular ganglion cell complex (GCC); however, average and central choroidal thickness 500 µm nasal, 1,000 µm nasal and temporal to the fovea, central and parafoveal macular GCC, retinal nerve fiber layer, and inner plexiform layer, and central macular thickness did not change significantly. Various regional analyses showed several other significant differences. The findings of the current study confirm that some retinal layers are altered in AMD patients compared to healthy controls. Thus, future studies are required to derive more definitive conclusions.

Choroidal Vasculature Changes in Age-Related Macular Degeneration: From a Molecular to a Clinical Perspective

The contribution of choroidal vasculature to the pathogenesis of age-related macular degeneration (AMD) has been long debated. The present narrative review aims to discuss the primary molecular and choroidal structural changes occurring with aging and AMD with a brief overview of the principal multimodal imaging modalities and techniques that enable the optimal in vivo visualization of choroidal modifications. The molecular aspects that target the choroid in AMD mainly involve human leukocyte antigen (HLA) expression, complement dysregulation, leukocyte interaction at Bruch’s membrane, and mast cell infiltration of the choroid. A mechanistic link between high-risk genetic loci for AMD and mast cell recruitment has also been recently demonstrated. Recent advances in multimodal imaging allow more detailed visualization of choroidal structure, identifying alterations that may expand our comprehension of aging and AMD development.

Baseline Sattler Layer-Choriocapillaris complex Thickness cutoffs associated with age-related macular degeneration progression

PURPOSE

This study aims to assess the relationship between choroidal overall and sublayer thickness and AMD stage progression.

METHODS

A prospective, observational case series was performed. 262 eyes of 262 patients with different stages of AMD were imaged by Optical Coherence Tomography (OCT). AMD stage, choroidal thickness (CT), Sattler layer-choriocapillaris complex thickness (SLCCT) and Haller layer thickness (HLT) were determined at the baseline visit, at a 1-year follow-up visit, at a 2-year follow up visit and at a final visit (performed after a mean of 5 ± 1 years from the baseline visit).

RESULTS

Baseline AMD stages were distributed as follows: early AMD (30 eyes; 12%), intermediate AMD (97 eyes; 39%) and late AMD (126 eyes; 49%). At the final follow-up, AMD stages were so distributed: early AMD (14 eyes; 6%), intermediate AMD (83 eyes; 33%) and late AMD (156 eyes; 61%). Each group showed a statistically significant decrease in CT values over the entire follow-up (p <0.001) and SLCCT reduction was associated with AMD progression (p <0.001). Moreover, SLCCT quantitative cutoffs <20.50 µm and <10.5 µm were associated with a moderate and high probability of AMD progression, respectively, and SLCCT quantitative cutoffs <18.50 µm and <8.50 µm implied a moderate and high probability of macular neovascularization (MNV) onset, respectively.

CONCLUSIONS

Progressive choroidal impairment contributes to AMD progression. Among choroidal layers, a reduced SLCCT is a promising biomarker of disease worsening and its quantitative evaluation could help to identify patients at higher risk of stage advancement.

Correlation of choroidal thickness with age in healthy subjects: automatic detection and segmentation using a deep learning model

PROPOSE

The proposed deep learning model with a mask region-based convolutional neural network (Mask R-CNN) can predict choroidal thickness automatically. Changes in choroidal thickness with age can be detected with manual measurements. In this study, we aimed to investigate choroidal thickness in a comprehensive aspect in healthy eyes by utilizing the Mask R-CNN model.

METHODS

A total of 68 eyes from 57 participants without significant ocular disease were recruited. The participants were allocated to one of three groups according to their age and underwent spectral domain optical coherence tomography (SD-OCT) or enhanced depth imaging OCT (EDI-OCT) centered on the fovea. Each OCT sequence included 25 slices. Physicians labeled the choroidal contours in all the OCT sequences. We applied the Mask R-CNN model for automatic segmentation. Comparisons of choroidal thicknesses were conducted according to age and prediction accuracy.

RESULTS

Older age groups had thinner choroids, according to the automatic segmentation results; the mean choroidal thickness was 253.7 ± 41.9 μm in the youngest group, 206.8 ± 35.4 μm in the middle-aged group, and 152.5 ± 45.7 μm in the oldest group (p < 0.01). Measurements obtained using physician sketches demonstrated similar trends. We observed a significant negative correlation between choroidal thickness and age (p < 0.01). The prediction error was lower and less variable in choroids that were thinner than the cutoff point of 280 μm.

CONCLUSION

By observing choroid layer continuously and comprehensively. We found that the mean choroidal thickness decreased with age in healthy subjects. The Mask R-CNN model can accurately predict choroidal thickness, especially choroids thinner than 280 μm. This model can enable exploring larger and more varied choroid datasets comprehensively, automatically, and conveniently.

Choroidal caverns in pachychoroid neovasculopathy

Background. Choroid plays an important role in the pathogenesis of retinal pathology. Choroidal cavern, a recently identifi ed fi nding of optical coherent tomography (OCT), has been described in some degenerative and atrophic forms of retinal pathology. In the literature, there are only a few studies of choroidal cavers in pachychoroid neovasculopathy, newly described form of age related macular degeneration.The aim: to perform a detailed analysis of choroidal structure on OCT scans of patients with pachychoroid neovasculopathy and to reveal the frequency of choroidal caverns identifi cation.Material and methods. The data of 30 patients (30 eyes) aged 64.4 ± 5.6 years with pachychoroid neovascularization were retrospectively analyzed. The patients underwent spectral OCT and OCT-angiography (OCTA) using a Spectralis device (Heidelberg Engineering, Germany). The protocol was “Posterior Pole”, consisting of 61 scans. To assess the structure of the choroid, an enhanced image depth (EDI) module was used. OCT angiography was performed with a scan area of 6 × 6 mm. These methods were compared to identify choroidal caverns.Results. On OCT subretinal type 1 neovascularization was revealed as a fl at detachment of the pigment epithelium and visualization of blood flow on OCTA in the lesion as angled vessels (21 eyes) or a seafan (9 eyes). On OCT-EDI scans, there was diffuse or local choroidal thickening of choroid with an increase in the vessels of the Haller’s layer and thinning of the choriocapillaries. Choroidal caverns appeared on OCT and en-face OCT as areas with low optical density, round or irregular, located in different layers of the chorioid, without hyperrefl ective boundaries. A typical sign of choroidal cavern is the tail of hypertransmission after the cavern toward the sclera. Choroidal caverns were found in 4 of 30 eyes (13.3 %) and were located both near the choroidal neovascularization lesion and beyond this area.Conclusion. The prevalence of choroidal cavities, a new choroidal biomarker, in pachychoroid neovasculopathy was 13.3 %. Identification of these changes is possible with the use of modern diagnostic techniques (OCT-EDI, OCTA and en-face OCT) that allow visualization the state of the choroid. The prognostic signifi cance of choroidal cavities requires further study.

CHOROIDAL IMAGING BIOMARKERS TO PREDICT HIGHLY RESPONSIVE AND RESISTANT CASES TREATED WITH STANDARDIZED ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR REGIMEN IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

PURPOSE

To determine structural predictors of treatment response in neovascular age-related macular degeneration analyzing optical coherence tomography (OCT)-related biomarkers.

METHODS

A retrospective review of patients undergoing treatment for neovascular age-related macular degeneration at a tertiary institute was performed at presentation. High-intensity regimen included eyes on long-term anti-vascular endothelial growth factor treatment with the inability to extend beyond a month without a relapse and needed double the dose of medication (n = 25). Low-intensity regimen had eyes that went into long-term remission after at least three injections and remained dry for more than a year until the last visit (n = 20). Multimodal imaging including fluorescein angiogram, OCT, and comprehensive ocular evaluation were done. Choroidal vascularity index, total choroidal area, luminal area, subfoveal choroidal thickness, choriocapillaris thickness and Haller and Sattler layer thickness were analyzed for statistical significance.

RESULTS

The groups had no significant difference at baseline in age, gender, incidence of reticular pseudodrusen, polypoidal choroidal vasculopathy feature on OCT, type of choroidal neovascular membrane, and geographic atrophy. Multinomial logistic regression revealed that thicker subfoveal choroidal thickness and larger total choroidal area were the significant predictors of poor response to anti-vascular endothelial growth factor treatment (E = 0.02; P = 0.02; E = 1.82; P = 0.0075).

CONCLUSION

Thicker subfoveal choroidal thickness and higher total choroidal area are useful variables to predict a poor treatment response.

Quantitative Modeling of Ultra-Widefield Choroidal Indocyanine Green Angiography in Systemic Vascular Diseases

BACKGROUND AND OBJECTIVE

To evaluate quantitative measurements of choroidal vasculature as obtained via ultra-widefield indocyanine green angiography (ICGA) in patients with systemic vascular diseases.

PATIENTS AND METHODS

Retrospective chart review and image analysis of 38 eyes from 21 patients with ICGA as part of routine retinal care. Images were binarized with lines drawn at specific antero-posterior landmarks. The vessel density and mean vessel caliber were measured along these lines and correlated with systemic vascular disease status.

RESULTS

Unlike those with other systemic vascular diseases, patients with obstructive sleep apnea (OSA) were found to have increased choroidal vascular density and vessel caliber in all measurements of the peripheral choroid compared with those patients without (P < .05 for all measurements).

CONCLUSIONS

Patients with OSA may have increased vascular density secondary to increased choroidal vessel caliber. Further work is needed to validate the modeling and confirm the association. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:281-287.].

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.

Bruch's Membrane and the Choroid in Age-Related Macular Degeneration

A healthy choroidal vasculature is necessary to support the retinal pigment epithelium (RPE) and photoreceptors, because there is a mutualistic symbiotic relationship between the components of the photoreceptor/retinal pigment epithelium (RPE)/Bruch's membrane (BrMb)/choriocapillaris (CC) complex. This relationship is compromised in age-related macular degeneration (AMD) by the dysfunction or death of the choroidal vasculature. This chapter will provide a basic description of the human Bruch's membrane and choroidal anatomy and physiology and how they change in AMD.The choriocapillaris is the lobular, fenestrated capillary system of choroid. It lies immediately posterior to the pentalaminar Bruch's membrane (BrMb). The blood supply for this system is the intermediate blood vessels of Sattler's layer and the large blood vessels in Haller's layer.In geographic atrophy (GA), an advanced form of dry AMD, large confluent drusen form on BrMb, and hyperpigmentation (presumably dysfunction in RPE) appears to be the initial insult. The resorption of these drusen and loss of RPE (hypopigmentation) can be predictive for progression of GA. The death and dysfunction of CC and photoreceptors appear to be secondary events to loss in RPE. The loss of choroidal vasculature may be the initial insult in neovascular AMD (nAMD). We have observed a loss of CC with an intact RPE monolayer in nAMD, by making RPE hypoxic. These hypoxic cells then produce angiogenic substances like vascular endothelial growth factor (VEGF), which stimulate growth of new vessels from CC, resulting in choroidal neovascularization (CNV). Reduction in blood supply to the CC, often stenosis of intermediate and large blood vessels, is associated with CC loss.The polymorphisms in the complement system components are associated with AMD. In addition, the environment of the CC, basement membrane and intercapillary septa, is a proinflammatory milieu with accumulation of proinflammatory molecules like CRP and complement components during AMD. In this toxic milieu, CC die or become dysfunctional even early in AMD. The loss of CC might be a stimulus for drusen formation since the disposal system for retinal debris and exocytosed material from RPE would be limited. Ultimately, the photoreceptors die of lack of nutrients, leakage of serum components from the neovascularization, and scar formation.Therefore, the mutualistic symbiotic relationship of the photoreceptor/RPE/BrMb/CC complex is lost in both forms of AMD. Loss of this functionally integrated relationship results in death and dysfunction of all of the components in the complex.

Macular Functional and Morphological Changes in Intermediate Age-Related Maculopathy

Purpose

The purpose of this study was to evaluate macular preganglionic function and to verify its relationship with retinal and choroidal morphology in patients with intermediate age-related macular degeneration (iAMD) patients.

Methods

All included patients performed multifocal electroretinogram (mfERG) for investigating on macular function from the central 15° of foveal eccentricity, spectral domain optical coherence tomography (SD-OCT) for studying retinal structure, enhanced depth imaging OCT (EDI-OCT) for the measure of choroidal vascularity index (CVI), and OCT-angiography (OCTA) for the evaluation of vessel density (VD) in the superficial and deep capillary plexus, and choriocapillaris (CC) layer.

Results

Twenty-seven patients with iAMD and 20 age-matched control eyes were analyzed. Significantly (P < 0.01) delayed and reduced mfERG responses in the central 0 to 2.5°, paracentral 2.5 to 5°, and overall 0 to 5° areas, as well as increased CVI values in both foveal (1 mm centered to the fovea) and fovea + parafovea areas (3 mm centered to the fovea), increased foveal and parafoveal (annular area of 1-3 mm centered to the fovea) retinal pigment epithelium thickness, and volume and parafoveal outer retinal volume were found in iAMD eyes as compared to controls. Moreover, iAMD eyes showed significantly (P < 0.01) reduced foveal and parafoveal OCTA-VD values in the CC layer when compared to controls. In the iAMD group, not significant (P > 0.01) correlations were found between morphological and functional parameters.

Conclusions

Our findings support a dysfunction of photoreceptors and bipolar cells in both foveal and parafoveal areas in the presence of outer retina, CC, and choroidal structural changes, however, not significantly correlated. The observed enlargement of luminal choroidal area (measured by CVI) is possibly compensatory to CC vascular insufficiency.

Choroidal vascularity index determined by binarization of enhanced depth imaging optical coherence tomography images in eyes with intermediate age-related macular degeneration

Purpose

To evaluate choroidal structural changes in patients with intermediate age-related macular degeneration using choroidal vascularity index.

Methods

The eyes of patients with intermediate age-related macular degeneration and controls were evaluated with enhanced depth imaging optical coherence tomography images. Subfoveal choroidal area was segmented into luminal area and stromal area by the binarization technique on enhanced depth imaging optical coherence tomography images using ImageJ software. Choroidal vascularity index was defined as the ratio of luminal area to total circumscribed subfoveal choroidal area.

Results

Fifty-seven eyes with intermediate age-related macular degeneration and 60 healthy control eyes were included in the study. The choroidal vascularity index was computed as 59.53% ± 4.9% in the intermediate age-related macular degeneration group and as 62.7% ± 4.3% in the control group ( p = 0.002). Patients with age-related macular degeneration showed significantly lower values of stromal area and higher values of luminal area compared to control subjects (0.51 ± 0.22 vs 0.87 ± 0.21, p < 0.001 and 0.74 ± 0.22 vs 0.52 ± 0.18, p < 0.001, respectively).

Conclusion

Eyes with intermediate age-related macular degeneration demonstrated reduced choroidal vascularity index compared to healthy eyes. Choroidal vascularity index seems to be a potential non-invasive quantitative method for studying structural changes of the choroid in patients with intermediate age-related macular degeneration.

Subfoveal Choroidal Thickness as a Potential Predictor of Clinical Response to Stereotactic Radiotherapy for Neovascular Age-Related Macular Degeneration

BACKGROUND AND OBJECTIVE

Stereotactic radiotherapy (SRT) is a new adjuvant treatment modality that has been shown to reduce the need for repetitive intravitreal injections (IVIs) in patients with neovascular age-related macular degeneration (nAMD). The authors aimed to determine baseline predictors of clinical response to SRT.

PATIENTS AND METHODS

This was a retrospective, observational case series of patients with nAMD who underwent SRT and subsequently had at least 12 months of complete follow-up. After SRT and one mandatory IVI, patients were examined every 4 weeks and received further treatment on a pro re nata basis. Examination included enhanced depth imaging spectral-domain optical coherence tomography (SD-OCT) to measure subfoveal choroidal thickness (SFCT) and central macular thickness (CMT). Patients' data were retrieved from medical records and included demographics, disease duration, lesion size, best-corrected visual acuity (BCVA), previous number of IVIs, and type of drug applied.

RESULTS

A total of 35 eyes of 35 patients (76.23 years ± 7.05 years) were included, and 21 eyes (60%) responded well to SRT. The annual injection rate decreased from 6.86 before SRT to 3.46 afterward, whereas BCVA improved from 0.49 logMAR at baseline to 0.37 logMAR at final follow-up. From a morphologic point of view, CMT and SFCT decreased by 71 μm and 37 μm, respectively, at 12-month follow-up compared to baseline. Of all investigated parameters, only SFCT proved to be significant, as a higher baseline SFCT was found to be a strong negative predictor for the number of IVIs needed after SRT (regression coefficient: -0.678; P < .001).

CONCLUSIONS

Baseline SFCT may help predict which patients with nAMD will respond more favorably to SRT. The authors found eyes with a thicker baseline SFCT needed fewer IVIs after SRT. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:320-328.].

Subfoveal choriocapillaris, Sattler's and Haller's layer thickness predict clinical response to stereotactic radiotherapy in neovascular age-related macular degeneration patients

Purpose

To evaluate the significance of choroidal substructure analysis in predicting the clinical response to adjuvant stereotactic radiotherapy (SRT) in neovascular age-related macular degeneration (nAMD) patients.

Methods

Patients with nAMD, who underwent SRT (baseline) in addition to common intravitreal injections (IVIs) and subsequently had at least 12 months of complete follow-up, were enrolled. In a post hoc analysis, optical coherence tomography (OCT) data were reviewed, and subfoveal choroidal thickness (CT) as well as the thickness of choroidal substructures, such as choriocapillaris (CC), Sattler's layer (SL), and Haller's layer (HL), was measured to determine if these influenced SRT efficacy.

Results

A total of 35 eyes of 35 patients were included. While each of the 4 choroidal metrics significantly forecasts the clinical response to SRT, combining them all together produced the most reliable prediction model.

Conclusion

In terms of clinical response to SRT in nAMD patients, choroidal substructure analysis does improve the quality of the prediction model when combined with subfoveal CT.

Role of the Choroid in Age-related Macular Degeneration: A Current Review

Age-related macular degeneration (AMD) is a major cause of vision loss in the developed world and its pathogenesis is a topic of active research. To date, much study has been focused on the role of the retinal pigment epithelium (RPE) and Bruch's membrane (BrM) in AMD pathogenesis, but the role of the choroid has also been investigated. In this review, we focus on recent advancements in research in the role of the choroid in AMD, beginning with an exploration of the histopathologic, cellular and molecular changes that occur in the choroid in AMD and concluding by discussing new choroidal imaging techniques and patterns seen on fluorescein angiography, indocyanine green angiography, spectral-domain optical coherence tomography and optical coherence tomography angiography. Exploring these domains will lead to a better understanding of the factors at play beyond the outer retina in this important disease.

Thickness of retina and choroid in the elderly population and its association with Complement Factor H polymorphism: KLoSHA Eye study

PURPOSE

To analyze the associations of retinal and choroidal thickness on enhanced-depth imaging optical coherence tomography (EDI-OCT) with clinical, ophthalmic and genetic factors in the normal elderly population (aged 65 years or older).

METHODS

In this prospective, population-based cohort study, people aged 65 years or older were enrolled in the baseline study of the Korean Longitudinal Study on Health and Aging (KLoSHA) Eye Study. All participants underwent spectral domain-OCT scan using the EDI technique. A topographic map of the retina was obtained and subfoveal choroidal thickness (SFCT) was measured manually. Blood samples from all subjects were genotyped for major age-related macular degeneration (AMD)-associated single nucleotide polymorphisms (SNPs) the major AMD-associated SNPs; CFH Y402H rs1061170, CFH I62V rs800292, ARMS2 A69S rs10490924. A statistical analysis was conducted to compare the retinal thickness, choroidal thickness, and AMD risk genotypes.

RESULTS

Among the three hundred eighty people enrolled, the mean age was 76.6 years (range 65-99 years). Factors that showed correlation with either tomographic retinal parameters, retinal nerve fiber layer, or SFCT, were age and gender. Significant age-related decrease in thickness was observed in the RNFL, mean central thickness (MCT) and SFCT. Gender differences existed in central foveolar thickness (CFT) and MCT, where it was thicker in men. While chorioretinal parameters were not related with other genotypes, CFH rs1061170 risk genotype was significantly associated with thin SFCT. The group containing the AMD- risk allele (CT) had a 14.7% reduction in the SFCT compared to the non-risk TT group.

CONCLUSIONS

In addition to the well-known association with AMD, CFH rs1061170 is a significant genetic risk factor associated with choroidal thinning in normal eyes of the elderly population. Such findings may provide further insight into the pathogenesis of age-related macular degeneration as well as normal aging. In addition, our study provides the first normative data on retinal and choroidal thickness in population-based aged groups with a mean age over seventy-five.

Comparing imaging capabilities of spectral domain and swept source optical coherence tomography angiography in healthy subjects and central serous retinopathy

Background

There are two forms of system implementation of optical coherence tomography angiography (OCTA) in ophthalmic imaging, i.e., spectral domain (SD-) and swept source OCTA (SS-OCTA). The purpose of this paper is to compare the SD-OCTA and SS-OCTA for elucidating structural and vascular features associated with central serous retinopathy (CSR), and to evaluate the effects of CSR on SD- and SS-OCTA’s imaging capabilities.

Methods

Normal subjects and CSR patients were imaged by SD- and SS-OCTA using 3 × 3 mm and 6 × 6 mm scan patterns. OCT signal strengths at the superficial retina, deep retina, Sattler’s layer and Haller’s layer were used to compare the ability of SD- and SS-OCTA to image structural features. In addition, the ability to acquire angiograms were discussed by evaluating retinal vessel density. Central serous volume (CSV) was measured and it was correlated with difference in signal strengths (∆S) between two OCTA devices.

Results

Seven normal eyes and seven diseased eyes were recruited. Results showed no significant differences between SD- and SS-OCT in detecting structural features of the retinal layer according to the paired t-test. However, when imaging the Sattler’s layer for normal eyes, a significant difference is found between SD- and SS-OCT (p < 0.0001 for 3 × 3 mm scan, and p = 0.0002 for 6 × 6 mm); while for CSR eyes, the corresponding values were p < 0.0001 and p = 0.0003, respectively. At Haller’s layer for normal eyes, the corresponding values were p = 0.0004 and p = 0.0014; and for CSR eyes, p = 0.0004 and p < 0.0001, respectively. A strong correlation between ∆S and CSV was observed in the Sattler’s layer (3 × 3 mm – p = 0.0031 and R² = 0.951; 6 × 6 mm – p = 0.0075 and R² = 0.911) and Haller’s layer (3 × 3 mm – p = 0.0026 and R² = 0.955; 6 × 6 mm – p = 0.0013 and R² = 0.972).

Conclusions

The results suggest no differences between SD- and SS-OCTA for imaging the retinal layers however, when imaging beyond retinal layers, SS-OCTA appears advantageous in detecting returning signals. In CSR cases, the CSV may have an impact on sub-CSR tissue imaging and appears to have more impact on SD- than SS-OCTA.

Clinical histopathology of intrachoroidal splitting in open-globe injury: A retrospective case series of four patients

PURPOSE:

The purpose of this study is to observe the characteristics of intrachoroidal splitting (ICS) associated with choroidal detachment due to open-globe injury.

METHODS:

A retrospective, observational case series study of four eyes diagnosed with choroidal detachment exhibited ICS. The in vivo pathologic changes of the ICS were recorded during surgery. Four specimens were obtained from the inner part of the ICS region. One specimen was stained with hematoxylin and eosin; one specimen was examined under scanning electron microscopy, and the other two specimens were examined under transmission electron microscopy.

RESULTS:

All four patients presented with vortex vein rupture associated with large-scaled mid-peripheral ICS. The histopathologic observations indicated that ICS occurred between the medium-sized and large-sized choroidal vessel layers. Large vascular indentations and medium-sized choroidal vessels were observed on the inner part of the split interface. Postoperative outcomes of the four patients were poor. Vision in all four patients was no light perception before or after surgery. Three eyes became atrophic with silicon oil tamponade and band keratopathy, one eye was eventually enucleated for cosmetic reason.

CONCLUSION:

Intrachoroidal tissue has the potential to split during trauma. The outcome of ICS with choroidal detachment in open-globe injury was poor.

Macular Choroidal Small-Vessel Layer, Sattler's Layer and Haller's Layer Thicknesses: The Beijing Eye Study

To study macular choroidal layer thickness, 3187 study participants from the population-based Beijing Eye Study underwent spectral-domain optical coherence tomography with enhanced depth imaging for thickness measurements of the macular small-vessel layer, including the choriocapillaris, medium-sized choroidal vessel layer (Sattler’s layer) and large choroidal vessel layer (Haller’s layer). In multivariate analysis, greater thickness of all three choroidal layers was associated (all P < 0.05) with higher prevalence of age-related macular degeneration (AMD) (except for geographic atrophy), while it was not significantly (all P > 0.05) associated with the prevalence of open-angle glaucoma or diabetic retinopathy. There was a tendency (0.07 > P > 0.02) toward thinner choroidal layers in chronic angle-closure glaucoma. The ratio of small-vessel layer thickness to total choroidal thickness increased (P < 0.001; multivariate analysis) with older age and longer axial length, while the ratios of Sattler’s layer and Haller’s layer thickness to total choroidal thickness decreased. A higher ratio of small-vessel layer thickness to total choroidal thickness was significantly associated with a lower prevalence of AMD (early type, intermediate type, late geographic type). Axial elongation-associated and aging-associated choroidal thinning affected Haller’s and Sattler’s layers more markedly than the small-vessel layer. Non-exudative and exudative AMD, except for geographic atrophy, was associated with slightly increased choroidal thickness.

Automated quantification of Haller's layer in choroid using swept-source optical coherence tomography

OBJECTIVE

To develop an algorithm for automated quantification of Haller's layer in choroid using swept-source optical coherence tomography (OCT).

BACKGROUND

So far, to understand the association of various diseases with structural changes of choroid, only gross indicators such as thickness, volume and vascularity index have been examined. However, certain diseases affect specific sublayers of the choroid. Accordingly, a need for targeted quantitation arises. In particular, there is significant interest in understanding Haller's layer, a choroidal sublayer comprising relatively large blood vessels. Unfortunately, its intricate vasculature makes, manual quantitation difficult, tedious, and error-prone. To surmount this difficulty, it is imperative to develop an algorithmic method.

METHODOLOGY

The primary contribution of this work consists in developing an approach for detecting the boundary between Haller's and Sattler's layers, the latter comprising medium-sized vessels. The proposed algorithm estimates vessel cross-sections using exponentiation-based binarization, and labels a vessel large if its cross-section exceeds certain statistically determined threshold. Finally, the desired boundary is obtained as a smooth curve joining the innermost points of such large vessels. On 50 OCT B-scans (of 50 healthy eyes), our algorithm was validated both qualitatively and quantitatively, by comparing with intra-observer variability. Extensive statistical analysis was performed using metrics including Dice coefficient (DC), correlation coefficient (CC) and absolute difference (AD).

RESULTS

The proposed algorithm achieved a mean DC of 89.48% (SD:5.03%) in close agreement with the intra-observer repeatability of 89.12% (SD:5.68%). Corresponding mean AD and mean CC were of 17.54 μm (SD:16.45μm) and 98.10% (SD:1.60%) which too approximate the respective intra-observer repeatability values 19.19 μm (SD:17.69 μm) and 98.58% (SD:1.12%).

CONCLUSION

High correlation between algorithmic and manual delineations indicates suitability of our algorithm for clinically analyzing choroid in greater finer details, especially, in diseased eyes.

Sex-Dependent Choroidal Thickness Differences in Healthy Adults: A Study Based on Original and Synthesized Data

PURPOSE

The purpose of this study is to determine the influence of sex on choroidal thickness (CT) in healthy adults.

METHODS

Healthy Chinese adults were recruited and complete ophthalmic examinations were performed. The choroid was imaged by swept-source optical coherence tomography and the macular CT in Early Treatment Diabetic Retinopathy Study grids was obtained by the intrinsic automated segmentation software. CT in males and females was compared after controlling other factors. All of the published studies in PubMed were systemically tracked, and a syntheses analysis of the combined data of the present study and previous studies was performed to address this issue further.

RESULTS

A total of 104 healthy adults were included, of whom 38 (37%) were male and 66 (63%) were female. Older age and longer axial length (AL) each were significantly associated with thinner CT. After controlling for age and AL, the foveal CT and average macular CT were 25.5 μm (95% CI: 0.5-50.4 μm) and 22.1 μm (95% CI: 2.7-41.4 μm) thicker in men than in women, respectively. Significant differences in CT between males and females were also observed in inner and outer rings after controlling for age and AL (P < 0.05). After strict screening, 15 previously reported studies were determined to be eligible for inclusion. The combination of data collected from 2821 males and 3389 females provided further evidence that the choroid is thicker in males, with a pooled mean difference of 19.5 μm (95% CI: 11.4 to 27.6) for foveal CT and 14.7 μm (95% CI: 6.8 to 22.6) for average CT.

CONCLUSION

Our study of Chinese subjects, along with the syntheses analysis, strengthens the evidence that CT is greater in males than in females, based on OCT measurements. This observation may be pertinent for the sex disparities in some clinical conditions related to CT.

Subfoveal choroidal thickness predicts macular atrophy in age-related macular degeneration: results from the TREX-AMD trial

BACKGROUND

Our purpose was to evaluate the relationship between subfoveal choroidal thickness (SCT) and development of macular atrophy (MA) in eyes with age-related macular degeneration (AMD).

METHODS

This was a prospective, multicenter study. Sixty participants (120 eyes) in the TREX-AMD trial (NCT01648292) with treatment-naïve neovascular AMD (NVAMD) in at least one eye were included. SCT was measured by certified reading center graders at baseline using spectral domain optical coherence tomography (SDOCT). The baseline SCT was correlated with the presence of MA at baseline and development of incident MA by month 18. Generalized estimating equations were used to account for information from both eyes.

RESULTS

Baseline SCT in eyes with MA was statistically significantly less than in those without MA in both the dry AMD (DAMD) (P = 0.04) and NVAMD (P = 0.01) groups. Comparison of baseline SCT between MA developers and non-MA developers revealed a statistically significant difference (P = 0.03). Receiver operating characteristic curve (ROC) analysis showed the cut-off threshold of SCT for predicting the development of MA in cases without MA at baseline was 124 μm (AUC = 0.772; Sensitivity = 0.923; Specificity = 0.5). Among eyes without MA at baseline, those with baseline SCT ≤124 μm were 4.3 times more likely to develop MA (Odds ratio: 4.3, 95% confidence interval: 1.6-12, P = 0.005) than those with baseline SCT >124 μm.

CONCLUSIONS

Eyes with AMD and MA had less SCT than those without MA. Eyes with less baseline SCT also appear to be at higher risk to develop MA within 18 months.

Choroidal Thickness and Choroidal Vessel Density in Nonexudative Age-Related Macular Degeneration Using Swept-Source Optical Coherence Tomography Imaging

Purpose

To analyze the relationship between choroidal thickness and the distribution of choroidal blood vessels in eyes with nonexudative AMD.

Methods

Eyes with a diagnosis of nonexudative AMD were imaged using a prototype 100-kHz swept-source (SS) optical coherence tomography (OCT) instrument (Carl Zeiss Meditec, Dublin, CA, USA) with a central wavelength of 1050 nm. We used an OCT cube scan pattern consisting of 512 × 512 A-scans over a 12 × 12 mm retinal area. The eyes were partitioned into two groups based on the presence or absence of reticular pseudodrusen (RPD). All scans were segmented using an automated algorithm. In addition, five eyes from each of the two groups were randomly chosen for manual segmentation. Binary choroidal vessels maps were generated from suitable OCT choroidal slabs, and the relationship between the density of large choroidal vessels and choroidal thickness was analyzed using an Early Treatment Diabetic Retinopathy Study–like target centered on the fovea.

Results

Twenty-five eyes were enrolled in each group. The automated algorithm produced accurate choroidal thickness maps with an average difference between the manual and automated segmentations of 13.7 μm. There was a significant and stable correlation between choroidal thickness and choroidal vessel density across the two groups. Both average choroidal thickness and vessel density were significantly lower in eyes with RPD.

Conclusions

Our fully automated choroidal segmentation algorithm was able to capture the different patterns of choroidal thickness over a wide area. Choroidal thickness has a clear relationship with the density of large choroid vessels in our sample, irrespective of the presence or absence of RPD.

Choroidal thinning: Alzheimer's disease and aging

INTRODUCTION

The purpose of this study was to measure and to compare macular choroidal thickness (CT) between patients with mild Alzheimer's disease (AD), patients without AD, and elderly patients.

METHODS

CT was measured manually in 13 locations at 500-μm intervals of a horizontal and a vertical section from the fovea. Linear regression models were used to analyze the data.

RESULTS

Fifty patients with a diagnosis of mild AD (73.1 years), 152 patients without AD (71.03 years), and 50 elderly without AD (82.14 years) were included. In the AD patients, CT was significantly thinner in all 13 locations (P < .001-comparing with age-match group), and comparing with the elderly group, a more pronounced difference was found in two locations temporal to the fovea.

DISCUSSION

Patients with AD showed a significant choroidal thinning even when compared with elderly subjects. The reduction of CT may aid in the diagnoses of AD, probably reflecting the importance of vascular factors in their pathogenesis.

MACULAR CHOROIDAL VOLUME CHANGES AFTER INTRAVITREAL BEVACIZUMAB FOR EXUDATIVE AGE-RELATED MACULAR DEGENERATION

PURPOSE

To evaluate the effect of intravitreal bevacizumab on the macular choroidal volume and the subfoveal choroidal thickness in treatment naïve eyes with exudative age-related macular degeneration.

METHODS

The macular choroidal volume and the subfoveal choroidal thickness were measured using enhanced depth imaging optical coherence tomography. After a screening examination, each patient received 3 monthly intravitreal injections of 1.25 mg bevacizumab. One month after the third injection was a final assessment.

RESULTS

Forty-seven patients with a mean age of 80 ± 6.4 years were included. The macular choroidal volume decreased significantly from median 4.1 mm (interquartile range 3.4-5.9) to median 3.9 mm (interquartile range 3.1-5.6) between the baseline and final examination (difference -0.46 mm, 95% confidence interval: -0.57 to 0.35, P < 0.001). Similarly, subfoveal choroidal thickness had decreased from 157.0 μm (interquartile range 116.0-244.5) at baseline to 139.0 μm (interquartile range 102.5-212.0) at the final examination (P < 0.001). Both parameters macular choroidal volume at baseline and subfoveal choroidal thickness at baseline were not associated with the response to treatment.

CONCLUSION

The macular choroidal volume and the subfoveal choroidal thickness decreased significantly after 3 monthly bevacizumab injections for exudative age-related macular degeneration.

REAL-TIME FULL-DEPTH VISUALIZATION OF POSTERIOR OCULAR STRUCTURES: Comparison Between Full-Depth Imaging Spectral Domain Optical Coherence Tomography and Swept-Source Optical Coherence Tomography

PURPOSE

To compare the real-time visualization of vitreoretino-choroidal structures using full-depth imaging (FDI) spectral domain optical coherence tomography (SD-OCT) and swept-source (SS)-OCT.

METHODS

Foveal scans using both FDI SD-OCT (Heidelberg Spectralis) and SS-OCT (Topcon Deep Range Imaging-OCT-1) were obtained in 40 normal eyes, 40 eyes with macular pathologies, and 40 eyes with glaucoma. Full-depth imaging SD-OCT images were obtained by manually enhancing the vitreoretinal interface first and then the choroid while averaging each OCT B-scan 100 times. Swept-source-OCT images were obtained by averaging each B-scan 96 times. After masking and randomly mixing the original OCT images, two independent physicians graded visualization of the premacular bursa, interdigitation zone line, and chorioscleral boundary, and also sharpness of choroidal structures.

RESULTS

A real-time full-depth image of vitreoretino-choroidal structures was successfully achieved with FDI SD-OCT in 118 cases (98.3%) and with SS-OCT in 45 cases (37.5%, P < 0.001). Full-depth imaging SD-OCT imaging was superior to SS-OCT imaging in visualizing the anterior border of the premacular bursa in 109 eyes (90.8%), with average grading of 1.63 ± 0.53 for the FDI SD-OCT and 0.39 ± 0.52 for the SS-OCT (P < 0.001). Swept-source-OCT was similar to FDI SD-OCT in visualizing the chorioscleral boundary in 108 eyes (90.0%), with average grading of 1.81 ± 0.39 for the SS-OCT and 1.78 ± 0.38 for the FDI-OCT (P = 0.566). The visualization of the interdigitation zone line was identical in the 2 imaging instruments (P = 1.000). The sharpness of the choroidal structures was greater with SS-OCT than with FDI-OCT (P < 0.001).

CONCLUSION

Manual double-enhancing FDI technique using SD-OCT provided a good compromise between vitreous and retinochoroidal structures visualization in real time during scanning procedure. In contrast, SS-OCT imaged well details of choroidal sublayers. Appropriate OCT technology and software should be selected according to its application in clinical settings.

Stereotactic radiotherapy in neovascular age-related macular degeneration: Real-life efficacy and morphological evaluation of the outer retina-choroid complex

Stereotactic radiotherapy (SRT) is a new approach to treat neovascular age-related macular degeneration (nAMD). The INTREPID trial suggested that SRT could reduce the frequency of regular intravitreal injections (IVIs) with antivascular endothelial growth factor drugs, which are necessary to control disease activity. However, the efficacy of SRT in nAMD and resulting morphological changes have not been validated under real-life circumstances, an issue, which we would like to address in this retrospective analysis.Patients who met the INTREPID criteria for best responders were eligible for SRT. A total of 32 eyes of 32 patients were treated. Thereafter, patients were examined monthly for 12 months and received pro re nata IVI of aflibercept or ranibizumab. Outcome measures were: mean number of injections, best-corrected visual acuity, and morphological changes of the outer retina-choroid complex as well as patient safety.Mean number of IVI decreased by almost 50% during the 12 months after SRT compared to the year before, whereas visual acuity increased by one line (logMAR). Morphological evaluation showed that most changes affect outer retinal layers.Stereotactic radiotherapy significantly reduced IVI retreatment in nAMD patients under real-life circumstances. Therefore, SRT might be the first step to stop visual loss as a result of IVI undertreatment, which is a major risk.

Ultra-Short-Term Reproducibility of Speckle-Noise Freed Fluid and Tissue Compartmentalization of the Choroid Analyzed by Standard OCT

PURPOSE

We measured reproducibility of speckle-noise freed fluid and tissue compartmentalization of the choroid (choroidal angiography and tissue characterization).

METHODS

This study included 26 eyes of 13 healthy females: 13 were used for repeated measurements and 13 were used for side comparison. A semiautomated algorithm removed speckle-noise with structure preservation.

RESULTS

Intraclass correlation (ICC), with respect to reproducibility of the method, showed an ICC for choroidal fluid inner space analysis (FISA) of 95.15% (90.01-98.24). The ICC of tissue inner space analysis (TISA) was 99.75% (99.47-99.91). The total choroid ratio (TCR), calculated from volumes of tissue to vessels, showed an ICC of 88.84% (78.28-95.82). Comparison of eyes (left to right) showed a difference for FISA of 0.033 (95% confidence interval [CI] -0.0018-0.0680, P = 0.063), TISA -0.118 (CI -0.2373-0.0023, P = 0.055), and TCR -0.590 (CI -0.9047 to -0.2754, P = 0.004). The ICC for FISA and TISA showed a trend in the difference comparing left and right eyes; however, TCR showed a significant difference between the eyes in the measured area (P < 0.001). Mean overall FISA was 0.58 mm³ (range, 0.25-0.98 mm³, SD = 0.14). Mean TISA was 3.45 mm³ (range, 2.38-5.0 mm³, SD 0.072). Mean TCR was 6.13 (overall range, 3.93-10.2, SD = 1.34).

CONCLUSIONS

Differences in choroidal layers between subjects were found mainly due to alterations in choroidal tissue. Reproducibility of speckle-noise freed choroidal angiography appeared excellent.

TRANSLATIONAL RELEVANCE

Speckle noise is a granular "noise" that appears in a wide range of medical imaging methods as ultrasonography, magnetic resonance, computer tomography, or optical coherence tomography (OCT). Findings from basic science about speckle noise were translated into a novel, medical image postprocessing application that can separate signal from speckle noise with structure preservation with high reproducibility and enhance medical imaging.

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.

Multifunctional 1050 nm Spectral Domain OCT System at 147 kHz for Posterior Eye Imaging

We report a newly developed multifunctional 1050 nm spectral domain optical coherence tomography (SD-OCT) system working at 147 kHz A-scan rate for posterior eye imaging. It is demonstrated through in-vivo experiments that this system delivers not only superior performance of posterior eye structural imaging but also detailed visualization of microcirculation network in retina. The choroid of the eye with either myopic or normal conditions can clearly be visualized through the entire scanning volume. These results indicate great potential in applying this new system for clinical studies.

Resveratrol based oral nutritional supplement produces long-term beneficial effects on structure and visual function in human patients

Background: Longevinex^® (L/RV) is a low dose hormetic over-the-counter (OTC) oral resveratrol (RV) based matrix of red wine solids, vitamin D₃ and inositol hexaphosphate (IP6) with established bioavailability, safety, and short-term efficacy against the earliest signs of human atherosclerosis, murine cardiac reperfusion injury, clinical retinal neovascularization, and stem cell survival. We previously reported our short-term findings for dry and wet age-related macular degeneration (AMD) patients. Today we report long term (two to three year) clinical efficacy. Methods: We treated three patients including a patient with an AMD treatment resistant variant (polypoidal retinal vasculature disease). We evaluated two clinical measures of ocular structure (fundus autofluorescent imaging and spectral domain optical coherence extended depth choroidal imaging) and qualitatively appraised changes in macular pigment volume. We further evaluated three clinical measures of visual function (Snellen visual acuity, contrast sensitivity, and glare recovery to a cone photo-stress stimulus). Results: We observed broad bilateral improvements in ocular structure and function over a long time period, opposite to what might be expected due to aging and the natural progression of the patient’s pathophysiology. No side effects were observed. Conclusions: These three cases demonstrate that application of epigenetics has long-term efficacy against AMD retinal disease, when the retinal specialist has exhausted other therapeutic modalities.