Imaging of the peripheral retina

Age-Related Macular or Retinal Degeneration?

Age-related macular degeneration (AMD) is an eye disease that leads to progressive vision loss. Its prevalence has been increasing due to population aging. Previously, it was commonly believed that the disease affects the central retina, that is, the macula. However, recent studies have shown that it also involves the peripheral retina. Novel imaging techniques revealed various degenerative lesions that extend beyond the central macula. While their prevalence remains unknown, they seem to be more frequent in patients with late AMD. These findings suggest that the term "age-related retinal dysfunction" might be more adequate to describe some cases of AMD. They also raise the question about the role of electroretinography (ERG) as an objective measure of retinal function. The most common types of ERG tests used in AMD are multifocal (mfERG) and full-field ERG (ffERG). mfERG is more sensitive to macular changes, but the test is difficult to perform when fixation is unstable. On the other hand, ffERG reflects the function of the entire retina, not only the macular area. It helps assess the impact of peripheral retinal lesions and overall retinal function in patients with AMD. As ffERG results are normal in early-stage AMD, any abnormalities indicate that the disease is more severe and affects the entire retina. Anti-vascular endothelial growth factor injections improve retinal function in patients with neovascular AMD, as demonstrated by an increase in their ERG responses. More research is needed to assess the association between local and general retinal dysfunction. In this review, ffERG findings in patients with AMD are described and the usefulness of ffERG is discussed based on previous studies and cases from our own clinical practice.

Spectral-Domain Optical Coherence Tomography Imaging of the Typical cystoid degeneration

Purpose: To describe the spectral-domain optical coherence tomography (SD-OCT) features of typical cystoid degeneration.Methods: This was a retrospective study of 11 eyes with typical cystoid degeneration (TCD). All patients had a complete ocular examination, ultra-widefield (UWF) pseudocolor fundus photography and SD-OCT with a 55° wide-field lens. We analyzed the cross-sectional structural information of SD-OCT imaging with TCD.Results: On SD-OCT, the TCD regions exhibited rolling hills patterns with irregularly elevated retinal surface, and multiple intraretinal hyporeflective cavities separated by irregular septums were seen in the neurosensory retina. Destructive changes were seen in the ellipsoid zone and the pigment epithelium. Consolidated vitreous with moderate to high reflectivity was seen over the lesion and there might be vitreoretinal adhesions and tractions.Results: SD-OCT shows exquisite structural features of the anatomy in vivo detail of the TCD. This imaging technique may deepen our structural understanding of TCD and may influence decision-making in clinical practice.

Performance evaluation of two fundus oculi angiographic imaging system: Optos 200Tx and Heidelberg Spectralis

The present study aimed to compare the imaging performance of two ultra-wide-field fluorescein angiography imaging systems, namely the OptosOptomap 200Tx (Optos 200Tx) and the Heidelberg Spectralis (Spectralis). A total of 18 patients (36 eyes) underwent angiography using the two systems at the Department of Ophthalmology, Beijing Friendship Hospital (Beijing, China) between January and June 2017. The images were obtained as a single shot centered on the macula. The total area and area within each of four visualized quadrants were calculated and compared. The averages of the total and individual quadrant area captured by the Optos 200Tx were all larger than those obtained with the Spectralis (P<0.05). For pair-wise comparison, the circular area centered on the macula (radius of 10 and 15 mm) was displayed: Optos 200Tx 10 mm (295.57 mm²) < Spectralis (520.11 mm²) < Optos 200Tx 15 mm (596.45 mm²) < Optos 200Tx (804.36 mm²) (P<0.01). The differences of each of the four quadrant areas were statistically significant between the two systems (P<0.05). The mean size of the areas was in the following order: Inferior < temporal < superior < nasal for the Optos 200Tx, and inferior < temporal < nasal < superior for the Spectralis. Further comparison of the four-quadrant area indicated that the inferior quadrant of the Optos 200Tx was smaller than the other three quadrants (P<0.01) and the inferior quadrant of the Spectralis was smaller than the superior quadrant (P<0.01). The total retinal area and the retinal area of each quadrant captured by the Optos 200Tx were larger than those captured with the Spectralis. The total retinal area captured with the Optos 200Tx was able to cover the mid-peripheral area and part of the far-peripheral area of the retina, whereas the Spectralis only covered the mid-peripheral area.

Angiopoietin-2 as a Marker of Retinopathy in Children and Adolescents With Sickle Cell Disease: Relation to Subclinical Atherosclerosis

OBJECTIVES

Angiopoietin-2 (Ang-2) is a multifaceted cytokine that functions in both angiogenesis and inflammation. A proangiogenic state has been found in adults with sickle cell disease (SCD), mainly because of elevated Ang-2 levels. We determined Ang-2 level in 40 children and adolescents with SCD compared with 40 healthy controls and assessed its relation to retinopathy as well as carotid intimamedia thickness (CIMT).

METHODS

Hematologic profile, serum ferritin, and serum Ang-2 were measured. CIMT was assessed using high-resolution ultrasound. Fundus examination was performed followed by fundus fluorescein angiography. Optical coherence tomography angiography (OCTA) was used to find small vascular changes not clinically manifested.

RESULTS

Ang-2 levels and CIMT were significantly higher in SCD patients compared with controls. The incidence of nonproliferative retinopathy was 45%. SCD patients with retinopathy were older in age with a history of sickling crisis of >3 attacks per year and had a higher incidence of sickle cell anemia than sickle β-thalassemia. Ang-2 cutoff value 9000 pg/mL could significantly detect the presence of retinopathy among SCD patients with 100% sensitivity and specificity. Serum Ang-2 levels were positively correlated with HbS and CIMT. Logistic regression analysis revealed that Ang-2 and HbS significantly contribute to retinopathy among patients with SCD.

CONCLUSIONS

Elevated Ang-2 highlights the role of angiogenesis in the pathophysiology of SCD and may be considered a promising marker for screening of patients at risk of sickle retinopathy and vascular dysfunction.

Peripheral retinal findings in populations with macular disease are similar to healthy eyes

PURPOSE

Recent evidence suggests several macular diseases are associated with peripheral retinal changes. This study investigated the number, type and management consequences of peripheral retinal findings detected in patients attending a referral only, eye-care clinic, the Centre for Eye Health(CFEH) with macular disease.

METHODS

Records of 537 patients attending CFEH for a macular assessment were included in the study. Subjects were classified as having age-related macular degeneration (AMD), epiretinal membrane (ERM), central serous chorioretinopathy (CSCR), inherited macular dystrophy or no macular disease. Data extracted included reason for referral, macular findings, peripheral findings (based on examination by ultra-widefield scanning laser ophthalmoscopy), diagnosis and management.

RESULTS

After age-matching, the number of peripheral findings in subjects with AMD, ERM or CSCR was not significant different to normal subjects. The most common finding for all cohorts were non-specific, degenerative changes such as drusen or pigmentation (61-72%) except inherited macular dystrophy subjects who had mostly vascular findings (30%; p < 0.05). Subjects with AMD and ERM with peripheral findings were significantly more likely to be reviewed or referred to an ophthalmologist than discharged back to their community eye care provider compared to subjects without findings. However only 8% of subjects had altered management based specifically on peripheral findings suggesting the macular findings in most subjects dictated their management. For those with a change, it was significant (upgrade to referral to an ophthalmologist). Peripheral findings also flagged 5% of subjects with vascular findings for referral to their general practitioner (GP).

CONCLUSIONS

Overall, the percentage and distribution of peripheral retinal findings in some macular diseases was similar to normal subjects. However, subjects with peripheral findings appeared to have significant differences in management. Considering some common findings, such as peripheral drusen may be relevant to AMD pathogenesis and therefore affect management of this disease, assessment of the peripheral retina should not be overlooked when the clinical focus is on the posterior pole.

Surface-Coil MRI for Small Peripheral Choroidal Melanoma: Imaging in a Rabbit Eye Model

Introduction

Imaging of small peripheral choroidal melanomas remains challenging in clinical and experimental settings, requiring wide-field ophthalmoscopy modalities. In this study, we applied surface-coil MRI to assess imaging feasibility for small peripherally located choroidal melanoma in a rabbit eye model.

Methods

A female albino rabbit with a body weight of 2.8 kg was immunosuppressed with intramuscular cyclosporine 15 mg/kg daily for 3 days prior to inoculation of 14 million 92.1 line melanoma cells into the peripheral suprachoroidal space of the right eye. The experimental animal continued to receive the same dosage of cyclosporine daily for 26 days postinoculation until the day of sacrifice. On that interval, it underwent surface-coil MRI scanning using various protocols and models subsequently sacrificed to allow histological evaluation. A comparative examination of various MRI sequences for optimal lesion imaging was performed, based on semiquantitative criteria.

Results

Imaging quality and superimposed artifacts varied across different sequences and the optimal tumor delineation from adjacent tissues was achieved in T1-weighted sequences.

Conclusions

MRI of small peripheral choroidal melanomas is feasible in a rabbit model using surface coils, particularly in T1-weighted sequences. Findings may be used as a basis for further development of this technique for experimental and clinical applications.

Peripheral Retinal Imaging Biomarkers for Alzheimer's Disease: A Pilot Study

PURPOSE

To examine whether ultra-widefield (UWF) retinal imaging can identify biomarkers for Alzheimer's disease (AD) and its progression.

METHODS

Images were taken using a UWF scanning laser ophthalmoscope (Optos P200C AF) to determine phenotypic variations in 59 patients with AD and 48 healthy controls at baseline (BL). All living participants were invited for a follow-up (FU) after 2 years and imaged again (if still able to participate). All participants had blood taken for genotyping at BL. Images were graded for the prevalence of age-related macular degeneration-like pathologies and retinal vascular parameters. Comparison between AD patients and controls was made using the Student t test and the χ2 test.

RESULTS

Analysis at BL revealed a significantly higher prevalence of a hard drusen phenotype in the periphery of AD patients (14/55; 25.4%) compared to controls (2/48; 4.2%) [χ2 = 9.9, df = 4, p = 0.04]. A markedly increased drusen number was observed at the 2-year FU in patients with AD compared to controls. There was a significant increase in venular width gradient at BL (zone C: 8.425 × 10-3 ± 2.865 × 10-3 vs. 6.375 × 10-3 ± 1.532 × 10-3, p = 0.008; entire image: 8.235 × 10-3 ± 2.839 × 10-3 vs. 6.050 × 10-3 ± 1.414 × 10-3, p = 0.004) and a significant decrease in arterial fractal dimension in AD at BL (entire image: 1.250 ± 0.086 vs. 1.304 ± 0.089, p = 0.049) with a trend for both at FU.

CONCLUSIONS

UWF retinal imaging revealed a significant association between AD and peripheral hard drusen formation and changes to the vasculature beyond the posterior pole, at BL and after clinical progression over 2 years, suggesting that monitoring pathological changes in the peripheral retina might become a valuable tool in AD monitoring.

Ultra-widefield fundus autofluorescence in age-related macular degeneration

Background

Establish accuracy and reproducibility of subjective grading in ultra-widefield fundus autofluorescence (FAF) imaging in patients with age-related macular degeneration (AMD), and determine if an association exists between peripheral FAF abnormalities and AMD.

Methods

This was a prospective, single-blinded case-control study. Patients were consecutively recruited for the study. Patients were excluded if there was a history of prior or active ocular pathology other than AMD or image quality was insufficient for analysis as determined by two independent graders. Control patients were those without any evidence of AMD or other ophthalmic disease apart from cataract. Using the Optos 200Tx (Optos, Marlborough, MA, USA), a ResMax central macula and an ultra-widefield peripheral retina image was taken for each eye in both normal color and short wavelength FAF. Ultra-widefield photographs were modified to mask the macula. Each ResMax and ultra-widefield image was independently graded by two blinded investigators.

Results

There were 28 AMD patients and 11 controls. There was a significant difference in the average age between AMD patients and control groups (80 versus 64, respectively P<0.001). There was moderate, statistically significant agreement between observers regarding image interpretation (78.4%, K = 0.524, P<0.001), and 69.0% (K = 0.49, P<0.001) agreement between graders for FAF abnormality patterns. Patients with AMD were at greater risk for peripheral FAF abnormalities (OR: 3.43, P = 0.019) and patients with FAF abnormalities on central macular ResMax images were at greater risk of peripheral FAF findings (OR: 5.19, P = 0.017).

Conclusion

Subjective interpretation of FAF images has moderate reproducibility and validity in assessment of peripheral FAF abnormalities. Peripheral FAF abnormalities are seen in both AMD and control patients. Those with AMD, poor visual acuity, and macular FAF abnormalities are at greater risk.

WIDE-FIELD SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

To describe wide-field spectral domain optical coherence tomography morphologic relationships of the vitreous, retina, and choroid in healthy and pathologic eyes.

METHODS

Standardized horizontal, vertical, and two oblique (supertemporal to inferonasal and supranasal to inferotemporal) spectral domain optical coherence tomography sections were collected for each patient. For extramacular imaging, images were obtained from 8 locations: (1) nasal to the optic disk, (2) extreme nasal periphery, (3) superior to the superotemporal vascular arcade, (4) extreme superior periphery, (5) inferior to the inferotemporal vascular arcade, (6) extreme inferior periphery, (7) temporal to the macula, and (8) extreme temporal periphery. Wide-angle montage images of optical coherence tomography from equator-to-equator were composed with a montaging software.

RESULTS

Wide-field spectral domain optical coherence tomography scans were obtained in 10 healthy subjects, in 7 patients with central serous chorioretinopathy, in 5 patients with wet age-related macular degenerations, in 5 patients with dry age-related macular degenerations, in 4 patients with retinitis pigmentosa, and in 1 patient with acute exudative polymorphous vitelliform maculopathy.

CONCLUSION

The novel approach of montaging spectral domain optical coherence tomography images to examine relationships between the choroid, retina, and associated structures adjacent to and outside of the macula may have a number of relevant applications in the study of vitreoretinal interface, paramacular and macular pathologic features.

Advances in retinal imaging modalities: Challenges and opportunities

Imaging in ophthalmology is playing an increasingly important role not only in screening, but also in monitoring and assessing response to treatment in an objective manner. Technical advances in various modes of imaging acquisition provide more detailed images. These can be combined and reviewed on one screen in the place of acquisition or sent for a remote assessment. Moreover, the machines are more user-friendly, which reduces the need for highly skilled technicians. In this article the authors describe currently available and experimental ophthalmic imaging modalities and their impact on clinical practice.