Peripheral autofluorescence and clinical findings in neovascular and non-neovascular age-related macular degeneration

Comparability of retinal thickness measurements using different scanning protocols on spectral-domain optical coherence tomography

Retinal thickness measurements obtained using optical coherence tomography (OCT) play an essential role both in multi-center clinical trials and in normal clinical practice. Different scanning protocols are available on most OCT devices, and it is important to ascertain whether the retinal thickness measurements obtained from these are comparable. This study aimed to compare retinal thickness measurements between raster and radial scanning protocols using spectral-domain OCT (SD-OCT). In a prospective study, 32 healthy subjects were scanned sequentially using raster and radial protocols from a SD-OCT device. For both the raster and radial OCT scans, retinal thicknesses were measured manually subfoveally and at 12 other points at 0.5 mm intervals temporally and nasally on the horizontal OCT B-scan passing through the fovea. The retinal thickness measurements were compared using intraclass correlation (ICC) and Bland-Altman plots. Subfoveal retinal thickness was 227.0 µm when measured on the raster scan and 229.2 µm on the radial scan, with a mean difference of 2.2 µm (P = 0.141).The ICC for agreement was 0.889 (95 % confidence interval 0.818-0.933). Similar results were observed for retinal thickness measurements at all other points, with mean differences ranging from -3.37 to 2.59 µm, and ICC values ranging from 0.837 to 0.972. The retinal thickness measurements obtained by the raster and radial scans of the same SD-OCT device are comparable, with differences of less than 4 µm. This is of relevance when measurements made using different OCT scan protocols are compared.

OPTOMAP WIDEFIELD IMAGING OF THE ARGUS II RETINAL PROSTHESIS IN PATIENTS WITH RETINITIS PIGMENTOSA

PURPOSE

To explore the utility of using ultra-widefield imaging to visualize the Argus II implant in the eyes of three patients with retinitis pigmentosa.

METHODS

Case series of three patients with retinitis pigmentosa who were implanted with the Argus II Retinal Prosthesis System; two of whom were enrolled in the Argus II clinical trial and one received the implant after the commercial release of the device. Optomap widefield fundus autofluorescence and color images of both eyes were taken in all three patients by an experienced technician using the Optos 200Tx imaging system. Analysis focused on fundus autofluorescence images of the implanted eyes and consisted of assessing the location and configuration of the Argus II electrode array and cable, and also the condition of the surrounding retina. Analysis was led by an experienced vitreoretinal surgeon.

RESULTS

Optos fundus autofluorescence images of the implanted eyes in all 3 patients gave a wide-angle view of the retina, with the electrode array and cable clearly visible. The status of the array and cable was able to be determined without difficulty. All 3 cases showed an appropriate mild-to-moderate bowing of the cable, and also the electrode array being positioned on or near the macula with a superotemporal tilt. Other features, such as "bone spicules," were also clearly seen. Optos color images were not as useful in the analysis because of an exaggerated green light artifact seen in the implanted versus the nonimplanted eyes.

CONCLUSION

Optomap fundus autofluorescence widefield images are useful in determining the configuration of the Argus II cable and the position of the electrode array on the retina and therefore are a useful component of the postoperative surveillance of patients implanted with the device. Using autofluorescence avoids the generation of a light reflection artifact often seen with Optos color imaging.

Prognostic implications of imaging in atrophic macular degeneration and its use in clinical practice and clinical trial design

Clinical prognostic markers in atrophic age-related macular degeneration include the extent of existing atrophy, fundus autofluorescence (FAF) patterns and optical coherence tomography changes in the outer retina/retinal pigment epithelium interface. The prognostic implications of these findings may be used to determine not just the rate of disease progression but also influence the likelihood, magnitude and clinical relevance of therapy responses. FAF phenotypes have been extensively investigated; however, the pathophysiological mechanisms behind their appearance have not been fully elucidated. Optical coherence tomography imaging is additive to FAF imaging in atrophic age-related macular degeneration, allowing the visualization of detail not available through FAF imaging whilst also displaying subtle changes correlating with the FAF phenotypes themselves, thereby giving clues to their histological determinates. The developing understanding of these imaging modalities and consequent development of prognostically useful classification systems have widespread implication in clinical care and clinical trial design.

Long-Term Follow-Up of Fundus Autofluorescence Imaging Using Wide-Field Scanning Laser Ophthalmoscopy

Aim: To evaluate the variation of peripheral alterations in different retinal diseases over a period of >3 years by using wide-field fundus autofluorescence (FAF) scanning laser ophthalmoscopy (SLO). Methods: A total of 26 eyes from 13 patients (median age 66 years, range 19-80) with age-related macular degeneration and other retinal degenerations were examined. In 2009, the Optos P200CAF prototype and from 2012 onwards, the Optos 200Tx (Optos plc, Scotland) were used for wide-field FAF SLO (excitation 532 nm). Results: The area involvement in outer retinal pathological alterations, such as atrophy and mottling of the retinal pigment epithelium far beyond the vascular arcades, was readily and better visualized within one image frame using wide-field FAF as compared to pseudocolor SLO of the same device. Over time, progression of existing and the development of de novo peripheral lesions were recorded with a concomitant enlargement of central lesions. In two cases (unilateral paravenous pigmented choroidal atrophy and suspected phenocopy of retinal dystrophy), no longitudinal changes of the topographic distribution of peripheral FAF intensities were noted. Conclusions: Wide-field FAF SLO allows the mapping of dynamic changes at the outer retina far beyond the vascular arcades. While its ability to detect and monitor these changes appears to be better than that of pseudocolor imaging, wide-field FAF SLO may not only be helpful to assess more widespread retinal dysfunction, but may also be useful for longitudinal assessments in natural history studies and interventional clinical trials.

Feasibility and clinical utility of ultra-widefield indocyanine green angiography

PURPOSE

To evaluate the feasibility and clinical utility of a novel noncontact scanning laser ophthalmoscope-based ultra-widefield indocyanine green angiographic system.

METHODS

Ultra-widefield indocyanine green angiographic images were captured using a modified Optos P200Tx that produced high-resolution images of the choroidal vasculature with up to a 200° field. Ultra-widefield indocyanine green angiography was performed on patients with a variety of retinal conditions to assess utility of this imaging technique for diagnostic purposes and disease treatment monitoring.

RESULTS

Ultra-widefield indocyanine green angiography was performed on 138 eyes of 69 patients. Mean age was 58 ± 16.9 years (range, 24-85 years). The most common ocular pathologies imaged included central serous chorioretinopathy (24 eyes), uveitis (various subtypes, 16 eyes), age-related macular degeneration (12 eyes), and polypoidal choroidal vasculopathy (4 eyes). In all eyes evaluated with ultra-widefield indocyanine green angiography, high-resolution images of choroidal and retinal circulation were obtained with sufficient detail out to 200° of the fundus.

CONCLUSION

In this series of 138 eyes, scanning laser ophthalmoscope-based ultra-widefield indocyanine green angiography was clinically practical and provided detailed images of both the central and peripheral choroidal circulation. Future studies are needed to refine the clinical value of this imaging modality and the significance of peripheral choroidal vascular changes in the diagnosis, monitoring, and treatment of ocular diseases.

Significance of the hyperautofluorescent ring associated with choroidal neovascularisation in eyes undergoing anti-VEGF therapy for wet age-related macular degeneration

AIM

To characterise the presence of a hyperautofluorescent (HAF) ring associated with choroidal neovascularisation (CNV) complex in patients with wet age-related macular degeneration (AMD).

METHODS

Fundus autofluorescence images and spectral-domain optical coherence tomography (OCT) scans from 362 eyes with wet AMD were reviewed. The presence and size of an HAF ring associated with the CNV complex was evaluated. A subgroup of 64 treatment-naive eyes with new-onset CNV was studied to analyse the relationship between pretreatment OCT characteristics and the presence of the HAF ring.

RESULTS

An HAF ring was present in 38% of the entire cohort of eyes and in 39% of treatment-naive eyes. The presence of the HAF ring was significantly correlated with the extent of baseline subretinal fluid (SRF) on OCT (p=0.0113), the number of antivascular endothelial growth factor (VEGF) injections (p=0.0439) and the number of treatment cycles (p=0.0154). Eyes with an HAF ring were more likely to have disruption of the ellipsoid zone line once the SRF was resolved compared with eyes without an HAF ring (p=0.0002). In multivariate analysis, the best predictors for HAF ring were the baseline area of SRF (p=0.0449) and the number of anti-VEGF treatments received (p=0.0568).

CONCLUSIONS

Nearly 40% of wet AMD eyes had an HAF ring. In treatment-naive eyes, the HAF ring had a significant association with SRF and was found as early as the baseline measurement and as long as 18 months after beginning treatment, persisting for up to 6 years after the initial diagnosis. Its association with baseline SRF and disruption of the ellipsoid zone line of the photoreceptors on OCT could indicate continuous stress on the outer retinal structures after exposure to prolonged SRF and/or transmitted autofluorescence from loss of the photoreceptors overlying the retinal pigment epithelium.

Area of peripheral retinal nonperfusion and treatment response in branch and central retinal vein occlusion

PURPOSE

To evaluate the extent of peripheral retinal nonperfusion in retinal vein occlusion and to determine its effect on the severity of macular edema and response to treatment.

METHODS

This prospective clinic-based cohort study included 32 consecutive patients with retinal vein occlusion and refractory macular edema evaluated using spectral domain optical coherence tomography and wide-field fluorescein angiography. Areas of ischemia were calculated as a percentage of the total visible retina (ischemic index), which was evaluated when macular edema was present (foveal central subfield >300 μm) and when edema had resolved (foveal central subfield ≤ 300 μm). Ischemic index was the main outcome measure.

RESULTS

The mean ischemic index at study enrollment was 14.8% and was larger when macular edema was present compared with when edema had resolved (14.8 vs. 10.3%, P < 0.001). Compared with those with less nonperfusion, patients with ischemic index >10% had thicker mean foveal central subfield on optical coherence tomography (520.8 vs. 424.5 μm, P = 0.029) and worse visual acuity (56.3 vs. 59 letters) with the presence of macular edema and experienced greater decrease in optical coherence tomography (296.1 vs. 165.3 μm, P = 0.019) and gain in visual acuity (12.4 vs. 0.9 letters, P = 0.036) in response to treatment.

CONCLUSION

The area of peripheral retinal nonperfusion is variable in patients with retinal vein occlusion and affects its clinical course and response to treatment.

Widespread choroidal thickening and abnormal midperipheral fundus autofluorescence characterize exudative age-related macular degeneration with choroidal vascular hyperpermeability

Purpose

To investigate the clinical findings that characterize exudative age-related macular degeneration (AMD) with choroidal vascular hyperpermeability (CVH).

Design

Retrospective comparative study.

Participants

Forty-eight consecutive patients attending the outpatient clinic of Tokyo University Hospital between May 2013 and July 2013.

Methods

The presence or absence of CVH was determined with indocyanine green angiography performed at the latest visit. When CVH was observed, the eye was categorized as CVH(+) AMD, otherwise it was categorized as CVH(-) AMD. Using high-penetration optical coherence tomography, we measured choroidal thickness at the fovea and at four midperipheral areas (mean choroidal thickness at points on 6- and 9-papilla diameter circles superior, inferior, temporal, and nasal to the fovea). Ultrawide field retinal imaging was used to investigate abnormalities in midperipheral fundus autofluorescence (FAF). Choroidal thickness and the proportion of FAF abnormalities were compared between the CVH(+) AMD and CVH(−) AMD eyes and between eyes with polypoidal choroidal vasculopathy and typical AMD. Multiple regression analysis was used to control for treatment history and other characteristics.

Results

CVH was observed in 17 cases. Choroidal thickness was higher in the CVH(+) AMD eyes than in the CVH(−) AMD eyes at the fovea (325 μm versus 229 μm, respectively; P=0.0010, t-test), superior point (277 μm versus 215 μm, respectively; P=0.0021, t-test), inferior point (225 μm versus 161 μm, respectively; P=0.0002, t-test), and nasal point (202 μm versus 165 μm, respectively; P=0.042, t-test). The significance was maintained after controlling for possible confounders. The choroid was thicker at the fovea and at the inferior point in polypoidal choroidal vasculopathy than in typical AMD. The rate of midperipheral FAF abnormality was significantly higher in the CVH(+) AMD eyes than in the CVH(−) AMD eyes (82% versus 48%, respectively; P=0.031).

Conclusion

AMD with CVH is associated with widespread choroidal thickening and peripheral FAF abnormalities.