In vivo evaluation of photoreceptor mosaic in early onset large colloid drusen using adaptive optics

The Development and Clinical Application of Innovative Optical Ophthalmic Imaging Techniques

The field of ophthalmic imaging has grown substantially over the last years. Massive improvements in image processing and computer hardware have allowed the emergence of multiple imaging techniques of the eye that can transform patient care. The purpose of this review is to describe the most recent advances in eye imaging and explain how new technologies and imaging methods can be utilized in a clinical setting. The introduction of optical coherence tomography (OCT) was a revolution in eye imaging and has since become the standard of care for a plethora of conditions. Its most recent iterations, OCT angiography, and visible light OCT, as well as imaging modalities, such as fluorescent lifetime imaging ophthalmoscopy, would allow a more thorough evaluation of patients and provide additional information on disease processes. Toward that goal, the application of adaptive optics (AO) and full-field scanning to a variety of eye imaging techniques has further allowed the histologic study of single cells in the retina and anterior segment. Toward the goal of remote eye care and more accessible eye imaging, methods such as handheld OCT devices and imaging through smartphones, have emerged. Finally, incorporating artificial intelligence (AI) in eye images has the potential to become a new milestone for eye imaging while also contributing in social aspects of eye care.

Polypoidal choroidal vasculopathy in a patient with early-onset large colloid drusen

Purpose

To report a case of a 46-year-old patient affected by polypoidal choroidal vasculopathy (PCV) in large colloid drusen (LCD) and to show how switching to intravitreal injection of aflibercept could be considered as a useful treatment of PCV not responsive to other anti-vascular endothelial growth factor (VEGF) injections.

Observations

A 46-year-old woman was referred to our department with diagnosis of early-onset retinal drusen. Multimodal imaging confirmed the diagnosis of LCD in both eyes, complicated by suggestive PVC in the left eye. Due to the absence of anatomical improvement after 6 intravitreal injections of ranibizumab, the patient was switched and treated by a single injection of aflibercept, showing a complete anatomical and functional recovery.

Conclusions and Importance

This case suggests progressive development of PCV as a possible late evolution of degenerating LCD. In case of exudative complication, intravitreal aflibercept injection could be considered as a useful treatment, especially in patients who are not responsive to others anti-VEGF injections.

Adaptive optics: principles and applications in ophthalmology

This is a comprehensive review of the principles and applications of adaptive optics (AO) in ophthalmology. It has been combined with flood illumination ophthalmoscopy, scanning laser ophthalmoscopy, as well as optical coherence tomography to image photoreceptors, retinal pigment epithelium (RPE), retinal ganglion cells, lamina cribrosa and the retinal vasculature. In this review, we highlight the clinical studies that have utilised AO to understand disease mechanisms. However, there are some limitations to using AO in a clinical setting including the cost of running an AO imaging service, the time needed to scan patients, the lack of normative databases and the very small size of area imaged. However, it is undoubtedly an exceptional research tool that enables visualisation of the retina at a cellular level.

ABNORMAL QUIESCENT NEOVASCULARIZATION IN A PATIENT WITH LARGE COLLOID DRUSEN VISUALIZED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

We report a case of large colloid drusen complicated by extensive quiescent choroidal neovascularization in both eyes.

METHODS

Case report.

RESULTS

A 46-year old woman was referred to our department with diagnosis of early-onset retinal drusen. Review of examinations performed 16 years before along with current multimodal imaging evaluation showed the presence of numerous large colloid drusen, subsequently replaced by quiescent choroidal neovascularization in both eyes, nicely visualized by optical coherence tomography angiography.

CONCLUSION

This case suggests progressive development of quiescent neovascularization beneath the drusen as a possible late evolution of degenerating large colloid drusens.

Choroidal Neovascularization and Geographic Atrophy are Potential Complications of Early Onset Large Colloid Drusen

The authors report a case of large colloid drusen (LCD) complicated by choroidal neovascularization (CNV) and geographic atrophy (GA). A 54-year-old man was referred to the authors' department with diagnosis of early onset retinal drusen. Multimodal imaging led to a diagnosis of LCD complicated by GA in the right eye and CNV in the left eye. The patient received a single injection of intravitreal aflibercept (Eylea; Regeneron, Tarrytown, NY) in the left eye. Six months later, best-corrected visual acuity improved to 20/25, and spectral-domain optical coherence tomography still showed absence of subretinal and intraretinal fluid. GA and CNV are possible complications of LCD, and contrary to previous beliefs, it should therefore not be considered as a benign condition. Intravitreal aflibercept could be considered as a useful treatment in cases complicated by CNV. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:586-590.].

Cone structure in subjects with known genetic relative risk for AMD

PURPOSE

Utilize high-resolution imaging to examine retinal anatomy in patients with known genetic relative risk (RR) for developing age-related macular degeneration (AMD).

METHODS

Forty asymptomatic subjects were recruited (9 men, 31 women; age range, 51 to 69 years; mean age, 61.4 years). Comprehensive eye examination, fundus photography, and high-resolution retinal imaging using spectral domain optical coherence tomography and adaptive optics were performed on each patient. Genetic RR scores were developed using an age-independent algorithm. Adaptive optics scanning light ophthalmoscope images were acquired in the macula extending to 10 degrees temporal and superior from fixation and were used to calculate cone density in up to 35 locations for each subject.

RESULTS

Relative risk was not significantly predictive of fundus grade (p = 0.98). Only patients with a high RR displayed drusen on Cirrus or Bioptigen OCT. Compared to an eye with a grade of 0, an eye with a fundus grade equal to or greater than 1 had a 12% decrease in density (p < 0.0001) and a 5% increase in spacing (p = 0.0014). No association between genetic RR and either cone density (p = 0.435) or spacing (p = 0.538) was found. Three distinct adaptive optics scanning light ophthalmoscope phenotypical variations of photoreceptor appearance were noted in patients with grade 1 to 3 fundi. These included variable reflectivity of photoreceptors, decreased waveguiding, and altered photoreceptor mosaic overlying drusen.

CONCLUSIONS

Our data demonstrate the potential of multimodal assessment in the understanding of early anatomical changes associated with AMD. Adaptive optics scanning light ophthalmoscope imaging reveals a decrease in photoreceptor density and increased spacing in patients with grade 1 to 3 fundi, as well as a spectrum of photoreceptor changes, ranging from variability in reflectivity to decreased density. Future longitudinal studies are needed in genetically characterized subjects to assess the significance of these findings with respect to the development and progression of AMD.

Retinal imaging using adaptive optics technology

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of wave front distortions. Retinal imaging using AO aims to compensate for higher order aberrations originating from the cornea and the lens by using deformable mirror. The main application of AO retinal imaging has been to assess photoreceptor cell density, spacing, and mosaic regularity in normal and diseased eyes. Apart from photoreceptors, the retinal pigment epithelium, retinal nerve fiber layer, retinal vessel wall and lamina cribrosa can also be visualized with AO technology. Recent interest in AO technology in eye research has resulted in growing number of reports and publications utilizing this technology in both animals and humans. With the availability of first commercially available instruments we are making transformation of AO technology from a research tool to diagnostic instrument. The current challenges include imaging eyes with less than perfect optical media, formation of normative databases for acquired images such as cone mosaics, and the cost of the technology. The opportunities for AO will include more detailed diagnosis with description of some new findings in retinal diseases and glaucoma as well as expansion of AO into clinical trials which has already started.

Assessing the cone photoreceptor mosaic in eyes with pseudodrusen and soft Drusen in vivo using adaptive optics imaging

PURPOSE

To investigate the cone photoreceptor mosaic in eyes with pseudodrusen as evidenced by the presence of subretinal drusenoid deposits (SDD) and conventional drusen using adaptive optics (AO) imaging integrated into a multimodal imaging approach.

DESIGN

Observational case series.

PARTICIPANTS

Eleven patients (11 eyes) with pseudodrusen and 6 patients (11 eyes) with conventional drusen.

METHODS

Consecutive patients were examined using near-infrared reflectance (IR) confocal scanning laser ophthalmoscopy (SLO) and eye-tracked spectral-domain optical coherence tomography (SD-OCT) and flood-illuminated retinal AO camera of nonconfluent pseudodrusen or conventional drusen. Correlations were made between the IR-SLO, SD-OCT, and AO images. Cone density analysis was performed on AO images within 50 × 50-μm windows in 5 regions of interest overlying and in 5 located between SDD or conventional drusen with the same retinal eccentricity.

MAIN OUTCOME MEASURES

Cone densities in the regions of interest.

RESULTS

The pseudodrusen correlated with subretinal accumulations of material in SD-OCT imaging and this was confirmed in the AO images. Defects in the overlying ellipsoid zone band as seen by SD-OCT were associated with SDD but not conventional drusen. The mean ± standard deviation cone density was 8964 ± 2793 cones/mm(2) between the SDD and 863 ± 388 cones/mm² over the SDD, a 90.4% numerical reduction. By comparison the mean cone packing density was 9838 ± 3723 cones/mm² on conventional drusen and 12,595 ± 3323) cones/mm² between them, a 21.9% numerical reduction. The difference in cone density reduction between the two lesion types was highly significant (P <0.001).

CONCLUSIONS

The pseudodrusen in these eyes correlated with subretinal deposition of material in multiple imaging modalities. Reduced visibility of cones overlying SDD in the AO images can be because of several possible causes, including a change in their orientation, an alteration of their cellular architecture, or absence of the cones themselves. All of these explanations imply that decreased cone photoreceptor function is possible, suggesting that eyes with pseudodrusen appearance may experience decreased retinal function in age-related macular degeneration independent of choroidal neovascularization or retinal pigment epithelial atrophy.

Adaptive optics retinal imaging--clinical opportunities and challenges

The array of therapeutic options available to clinicians for treating retinal disease is expanding. With these advances comes the need for better understanding of the etiology of these diseases on a cellular level as well as improved non-invasive tools for identifying the best candidates for given therapies and monitoring the efficacy of those therapies. While spectral domain optical coherence tomography offers a widely available tool for clinicians to assay the living retina, it suffers from poor lateral resolution due to the eye's monochromatic aberrations. Ophthalmic adaptive optics (AO) is a technique to compensate for the eye's aberrations and provide nearly diffraction-limited resolution. The result is the ability to visualize the living retina with cellular resolution. While AO is unquestionably a powerful research tool, many clinicians remain undecided on the clinical potential of AO imaging - putting many at a crossroads with respect to adoption of this technology. This review will briefly summarize the current state of AO retinal imaging, discuss current as well as future clinical applications of AO retinal imaging, and finally provide some discussion of research needs to facilitate more widespread clinical use.