Clinical evaluation of simultaneous confocal scanning laser ophthalmoscopy imaging combined with high-resolution, spectral-domain optical coherence tomography

Subretinal drusenoid deposits in non-neovascular age-related macular degeneration: morphology, prevalence, topography, and biogenesis model

PURPOSE

To characterize the morphology, prevalence, and topography of subretinal drusenoid deposits, a candidate histological correlate of reticular pseudodrusen, with reference to basal linear deposit (BlinD), a specific lesion of age-related macular degeneration, and to propose a biogenesis model for both lesion.

METHODS

Donor eyes with median death-to-preservation of 2:40 hours were postfixed in osmium tannic acid paraphenylenediamine and prepared for macula-wide high-resolution digital sections. Annotated thicknesses of 21 chorioretinal layers were determined at standard locations in sections through the fovea and the superior perifovea.

RESULTS

In 22 eyes of 20 white donors (83.1 ± 7.7 years), SDD appeared as isolated or confluent drusenoid dollops punctuated by tufts of retinal pigment epithelium apical processes and associated with photoreceptor perturbation. Subretinal drusenoid deposits and BlinD were detected in 85 and 90% of non-neovascular age-related macular degeneration donors, respectively. Subretinal drusenoid deposit was thick (median, 9.4 μm) and more abundant in the perifovea than in the fovea (P < 0.0001). BlinD was thin (median, 2.1 μm) and more abundant in the fovea than in the perifovea (P < 0.0001).

CONCLUSION

Subretinal drusenoid deposits and BlinD prevalence in age-related macular degeneration eyes are high. Subretinal drusenoid deposits organized morphology, topography, and impact on surrounding photoreceptors imply specific processes of biogenesis. Contrasting topographies of subretinal drusenoid deposits and BlinD suggest relationships with differentiable aspects of rod and cone physiology, respectively. A 2-lesion 2-compartment biogenesis model incorporating outer retinal lipid homeostasis is presented.

Successful subretinal delivery and monitoring of MicroBeads in mice

Background

To monitor viability of implanted genetically engineered and microencapsulated human stem cells (MicroBeads) in the mouse eye, and to study the impact of the beads and/or xenogenic cells on retinal integrity.

Methodology/Principal Findings

MicroBeads were implanted into the subretinal space of SV126 wild type mice using an ab externo approach. Viability of microencapsulated cells was monitored by noninvasive retinal imaging (Spectralis™ HRA+OCT). Retinal integrity was also assessed with retinal imaging and upon the end of the study by light and electron microscopy. The implanted GFP-marked cells encapsulated in subretinal MicroBeads remained viable over a period of up to 4 months. Retinal integrity and viability appeared unaltered apart from the focal damage due to the surgical implantation, GFAP upregulation, and opsin mistargeting in the immediate surrounding tissue.

Conclusions/Significance

The accessibility for routine surgery and its immune privileged state make the eye an ideal target for release system implants for therapeutic substances, including neurotrophic and anti-angiogenic compounds or protein based biosimilars. Microencapsulated human stem cells (MicroBeads) promise to overcome limitations inherent with single factor release systems, as they are able to produce physiologic combinations of bioactive compounds.

Autosomal recessive bestrophinopathy: differential diagnosis and treatment options

OBJECTIVE

To describe the clinical and genetic characteristics of patients with autosomal recessive bestrophinopathy (ARB).

DESIGN

Retrospective case series.

PARTICIPANTS

Ten patients with ARB from 7 different families.

METHODS

All patients underwent a complete ophthalmic examination, including dilated fundus examination, fundus photography, and fluorescein angiography (FA). In all probands, fundus autofluorescence (FAF) imaging, spectral-domain optical coherence tomography (OCT), full-field electroretinography (ERG), electro-oculography (EOG), and Goldmann perimetry were performed. In selected patients, multifocal ERG was performed. Blood samples were obtained to analyze the BEST1 gene for biallelic mutations that confirmed the diagnosis of ARB.

MAIN OUTCOME MEASURES

Age at onset; visual acuity; fundus appearance; characteristics on FA, FAF, OCT, full-field ERG, and EOG; BEST1 gene mutations; and genotype-phenotype correlation.

RESULTS

The age at onset varied widely, from 2 to 54 years. A spectrum of fundus abnormalities was observed, such as multifocal yellowish subretinal deposits, subretinal fibrous scars, and cystoid intraretinal fluid collections in the macula. All ARB patients were hyperopic, and some had shallow anterior chamber angles that predisposed them to angle-closure glaucoma. The EOG results were abnormal in all patients. The full-field ERG results were abnormal in 8 ARB patients, whereas 2 patients demonstrated normal cone and rod responses on full-field ERG. Nine ARB patients carried biallelic mutations in the BEST1 gene, and in 1 patient with a characteristic ARB phenotype, only 1 mutation could be identified. Seven different mutations were detected, including 4 novel mutations.

CONCLUSIONS

Autosomal recessive bestrophinopathy is a recognizable phenotype caused by autosomal recessively inherited mutations in the BEST1 gene. A differential diagnosis with other conditions can be made on the basis of marked autofluorescence changes in combination with an absent light rise on the EOG that outweighs the full-field ERG abnormalities, which point to the BEST1-related hereditary nature of the disease. A number of currently available therapeutic options should be considered in ARB, a disease that seems to be a suitable candidate for future gene therapy.

Detailed functional and structural characterization of a macular lesion in a rhesus macaque

PURPOSE

Animal models are powerful tools to broaden our understanding of disease mechanisms and to develop future treatment strategies. Here we present detailed structural and functional findings of a rhesus macaque suffering from a naturally occurring bilateral macular dystrophy (BMD), partial optic atrophy and corresponding reduction of central V1 signals in visual fMRI experiments when compared to data in a healthy macaque (CTRL) of similar age.

METHODS

Retinal imaging included infrared and autofluorescence recordings, fluorescein and indocyanine green angiography and spectral domain optical coherence tomography (OCT) on the Spectralis HRA + OCT platform. Electroretinography included multifocal and Ganzfeld-ERG recordings. Animals were killed and eyes analyzed by immunohistochemistry.

RESULTS

Angiography showed reduced macular vascularization with significantly larger foveal avascular zones (FAZ) in the affected animal (FAZBMD = 8.85 mm(2) vs. FAZCTRL = 0.32 mm(2)). OCT showed bilateral thinning of the macula within the FAZ (total retinal thickness, TRTBMD = 174 ± 9 µm) and partial optic nerve atrophy when compared to control (TRTCTRL = 303 ± 45 µm). Segmentation analysis revealed that inner retinal layers were primarily affected (inner retinal thickness, IRTBMD = 33 ± 9 µm vs. IRTCTRL = 143 ± 45 µm), while the outer retina essentially maintained its thickness (ORTBMD = 141 ± 7 µm vs. ORTCTRL = 160 ± 11 µm). Altered macular morphology corresponded to a preferential reduction of central signals in the multifocal electroretinography and to a specific attenuation of cone-derived responses in the Ganzfeld electroretinography, while rod function remained normal.

CONCLUSION

We provided detailed characterization of a primate macular disorder. This study aims to stimulate awareness and further investigation in primates with macular disorders eventually leading to the identification of a primate animal model and facilitating the preclinical development of therapeutic strategies.

Decreased retinal sensitivity and loss of retinal nerve fibers in multiple system atrophy

BACKGROUND AND AIM

In a previous study, retinal nerve fiber layer thickness (RNFLT) loss was shown as part of the neurodegenerative process in multiple system atrophy (MSA). Here, we investigate in a larger cohort of MSA patients whether the RNFLT loss translates into respective visual field defects.

METHODS

Spectral domain optical coherence tomography was performed in 20 MSA patients (parkinsonian subtype = 12, cerebellar subtype = 8) to quantify peripapillary RNFLT. Visual field (90°) was analyzed by automated static perimetry to investigate retinal structure/function relationship. Eight data sets did not meet stringent quality criteria, and only 12 data sets were further analyzed.

RESULTS

Compared to healthy controls, MSA patients demonstrated a significant reduction of RNFLT in the nasal sectors (p ( nasal-superior ) = 0.02, p ( nasal ) = 0.03, p ( nasal-inferior ) < 0.01), while changes in temporal RNFLT measures (p ( temporal-superior ) = 0.42, p ( temporal ) = 0.34, p ( temporal-inferior ) = 0.25) were not statistically significant compared to healthy controls (ANOVA). MSA patients featured a significant global mean deviation (2.74 dB; p < 0.01) without predominant peripheral visual field defects. Statistical analysis of mean defect in the central (0-30°), peripheral (30-90°) or global (0-90°) visual field revealed no significant correlation (r (2) (central) = 0.11, r (2) (peripheral) = 0.04, r (2) (global) = 0.07) with nasal RNFLT in MSA patients.

CONCLUSION

MSA patients feature significant reduction in nasal RNFLT and global mean deviation when compared to healthy controls, consistent with the multi-systemic nature of this neurodegenerative disorder. This finding provides first evidence for two independent deteriorations of the visual system in MSA.

Comparison of macular pigment in three types of macular telangiectasia

PURPOSE

To compare macular pigment in three types of macular telangiectasia (MacTel).

METHODS

Twenty-six eyes of 16 patients (mean age, 62 years) with MacTel were examined. The macular pigment optical density (MPOD) was obtained by autofluorescence spectrometry using two wavelengths (488 nm, 514 nm). The density of the central macular pigment within 0.5 degree around the foveal center (MPODc) was measured from a MPOD map.

RESULTS

Eight eyes of seven patients were classified as type 1, 16 eyes of eight patients as type 2, and two eyes of one patient as type 3. The macular pigment signal was seen in the area of fluorescein leakage in type 1 and the occlusive area in type 3; the macular pigment signal decreased in the area of fluorescein leakage in type 2. The mean MPODc (± standard deviation) was 0.40 ± 0.16 density unit (DU) (range, 0.17-0.57) in type 1; -0.08 ± 0.15 DU (range, -0.29-0.25) in type 2; and 0.32 ± 0.08 DU (range, 0.26-0.37) in type 3. Significant differences were seen between types 1 and 2 (P < 0.001) and types 2 and 3 (P = 0.007). There was no significant difference between types 1 and 3 (P = 0.765). In 30 age-matched normal eyes, the MPODc was 0.58 ± 0.11 DU (range, 0.38-0.79). There were significant differences between normal eyes and each MacTel subtype (type 1, P = 0.007; type 2, P < 0.001; type 3, P = 0.043).

CONCLUSIONS

The macular pigment values and distributions, including leakage or occlusion, differed in each MacTel type compared with fluorescein angiography findings. The capillary occlusion in type 3 is not associated with reduced MPOD.

Two-wavelength fundus autofluorescence and macular pigment optical density imaging in diabetic macular oedema

PURPOSE

To evaluate the application of 488 and 514 nm fundus autofluorescence (FAF) and macular pigment optical density (MPOD) imaging in diabetic macular oedema (DMO) and to demonstrate the typical imaging features.

PATIENTS AND METHODS

A hundred and twenty-five eyes of 71 consecutive patients with diabetic retinopathy who underwent examination at a specialist university clinic employing a modified Heidelberg Retina Angiograph, using two different light sources of 488 and 514 nm wavelength, were retrospectively reviewed. MPOD images were calculated using modified Heidelberg Eye Explorer software. All images were evaluated by two independent masked graders. Features from FAF and MPOD images were correlated with optical coherence tomography (OCT) imaging findings and inter-grader variability, sensitivity and specificity were calculated using OCT as reference.

RESULTS

Sixty-seven eyes had DMO on OCT. The inter-grader variability was 0.84 for 488 nm FAF, 0.63 for 514 nm FAF and 0.79 for MPOD imaging. Sensitivity and specificity for detection of DMO were 80.6 and 89.7% for 488 nm FAF; 55.2 and 94.8% for 514 nm FAF; and 80.6 and 91.4% for MPOD imaging. In 488 nm FAF and MPOD imaging, DMO was better visualised in comparison with 514 nm FAF imaging, P<0.01. MPOD revealed displacement of macular pigment by intraretinal cysts.

CONCLUSION

MPOD imaging, and particularly its combination with 488 nm and 514 nm FAF, provides a valuable addition to OCT in the evaluation of DMO and is clinically useful in rapid en-face assessment of the central macula.

Low limit for effective signal strength in the Stratus OCT in imperative low signal strength cases

Purpose

To determine the lowest limit of signal strength that is still effective for accurate analysis of optic coherence tomography (OCT) values, we investigated the reproducibility of OCT scans by signal strength (SS).

Methods

A total of 668 subjects were scanned for measurements of retinal nerve fiber layer (RNFL) thickness using the Stratus OCT twice on the same day. The variability of overall RNFL thickness parameters obtained at different SS was analyzed and compared by repeated-measures of ANOVA and Spearman's correlation coefficient. Values of the intraclass correlation coefficient (ICC) and variability (standard deviation) of RNFL thickness were obtained. The false positive ratio was analyzed.

Results

When SS was 3, the variability of RNFL thickness was significantly different (low ICC, high variability) in comparison to when SS was 4 or greater. Significant negative correlations were observed between variability in RNFL thickness and signal strength. The difference of variability of average RNFL thickness between SS 4 (4.94 µm) and SS 6 (4.41 µm) was 0.53 µm.

Conclusions

Clinically, the difference of variability of average RNFL thickness between SS 4 and SS 6 was quite small. High SS is important, however, when signal strength is low due to uncorrectable factors in patients in need of OCT for glaucoma and retinal disease. Our results suggest that SS 4 is the lowest acceptable limit of signal strength for obtaining reproducible scanning images.

Multimodal imaging of dry age-related macular degeneration

PURPOSE

The purpose of this study was to understand clinical significance of near-infrared reflectance (NIR), blue fundus autofluorescence (FAF) and near-infrared autofluorescence (NIA) in dry age-related macular degeneration (AMD), by correlation with fluorescein angiography (FA) and cross-sectional spectral domain optical coherence tomography (SD OCT).

METHODS

We evaluated 110 eyes (62 patients, mean age: 64 ± 8 years) diagnosed with dry AMD between January 2010 and December 2010, which underwent NIR (λ = 830 nm), FAF and FA (excitation λ = 488 nm; emission λ > 500 nm), NIA (excitation λ = 787 nm; emission λ > 800 nm), and simultaneous SD OCT scanning using a combined confocal scanning laser ophthalmoscope/SD OCT device (Spectralis HRA + OCT; Heidelberg Engineering, Heidelberg, Germany).

RESULTS

Drusen showed variable increased/decreased NIR, FAF, NIA and FA, which corresponded to variable increased/decreased thickness of the retinal pigment epithelium (RPE) and possible presence of subretinal deposits on SD OCT. Geographic atrophy (GA) was present in 43/110 eyes (39.0%) and showed increased NIR and fluorescence (FA), absent FAF and NIA, and loss of RPE on SD OCT. The hyperautofluorescence of the GA margin was never larger in FAF than that in NIA, while in 16.2% of cases, it was larger in NIA than that in FAF and corresponded to mild choroidal hyperreflectivity on SD OCT.

CONCLUSIONS

Simultaneous recording of SD OCT scans provided ultrastructural data for the evaluation of NIR, FAF, NIA and FA in dry AMD. Near-infrared autofluorescence might detect earlier than FAF areas of RPE cell loss at the GA margin.

Macular edema in central retinal vein occlusion: correlation between optical coherence tomography, angiography and visual acuity

To analyze the characteristics and the course of macular edema secondary to central retinal vein occlusion (CRVO) using optical coherence tomography (OCT) and to determine correlations between clinical, tomographic and angiographic data, in particular including retinal ischemia. In this retrospective study, 53 consecutive patients with CRVO were included. At each follow-up visit, patients underwent complete ophthalmological examination, including best-corrected visual acuity (BCVA) and OCT. Fluorescein angiography was performed at baseline and on demand during follow-up. 243 OCTs were analyzed. Mean age was 61 years and mean follow-up 13 months. The first structural change, observed very early after the onset of the occlusion, was a diffuse increase at the level of the outer nuclear layer without change at the level of the inner retina. This early change seemed characteristic of retinal vein occlusion. Cystoid spaces were subsequently observed in all retinal layers and were combined with serous retinal detachment in 51 %. During the first 6 months, central retinal thickness was higher in ischemic CRVO (mean, 691 μm) than in non-ischemic CRVO (mean, 440 μm, p < 0.01). In eyes with foveal thickness (central retinal thickness without subretinal fluid) of 700 μm or greater, peripheral ischemia was present in 69 % of eyes, final BCVA was 20/200 or less in 75 % and never reached 20/40 during follow-up. The integrity of the junction of the photoreceptors' inner and outer segments was correlated with a better prognosis (p < 0.05). Foveal thickness was inversely correlated to BCVA at each visit and could have a prognostic value. OCT examination in CRVO revealed useful data for the diagnosis of CRVO and its prognosis. The largest macular edemas seemed to be the hallmark of ischemic CRVO.

Optimization of in vivo confocal autofluorescence imaging of the ocular fundus in mice and its application to models of human retinal degeneration

PURPOSE

To investigate the feasibility and to identify sources of experimental variability of quantitative and qualitative fundus autofluorescence (AF) assessment in mice.

METHODS

Blue (488 nm) and near-infrared (790 nm) fundus AF imaging was performed in various mouse strains and disease models (129S2, C57Bl/6, Abca4(-/-), C3H-Pde6b(rd1/rd1), Rho(-/-), and BALB/c mice) using a commercially available scanning laser ophthalmoscope. Gray-level analysis was used to explore factors influencing fundus AF measurements.

RESULTS

A contact lens avoided cataract development and resulted in consistent fundus AF recordings. Fundus illumination and magnification were sensitive to changes of the camera position. Standardized adjustment of the recorded confocal plane and consideration of the pupil area allowed reproducible recording of fundus AF from the retinal pigment epithelium with an intersession coefficient of repeatability of ±22%. Photopigment bleaching occurred during the first 1.5 seconds of exposure to 488 nm blue light (∼10 mW/cm(2)), resulting in an increase of fundus AF. In addition, there was a slight decrease in fundus AF during prolonged blue light exposure. Fundus AF at 488 nm was low in animals with an absence of a normal visual cycle, and high in BALB/c and Abca4(-/-) mice. Degenerative alterations in Pde6b(rd1/rd1) and Rho(-/-) were reminiscent of findings in human retinal disease.

CONCLUSIONS

Investigation of retinal phenotypes in mice is possible in vivo using standardized fundus AF imaging. Correlation with postmortem analysis is likely to lead to further understanding of human disease phenotypes and of retinal degenerations in general. Fundus AF imaging may be useful as an outcome measure in preclinical trials, such as for monitoring effects aimed at lowering lipofuscin accumulation in the retinal pigment epithelium.

Simultaneous confocal scanning laser ophthalmoscopy combined with high-resolution spectral-domain optical coherence tomography: a review

We aimed to evaluate technical aspects and the clinical relevance of a simultaneous confocal scanning laser ophthalmoscope and a high-speed, high-resolution, spectral-domain optical coherence tomography (SDOCT) device for retinal imaging. The principle of confocal scanning laser imaging provides a high resolution of retinal and choroidal vasculature with low light exposure. Enhanced contrast, details, and image sharpness are generated using confocality. The real-time SDOCT provides a new level of accuracy for assessment of the angiographic and morphological correlation. The combined system allows for simultaneous recordings of topographic and tomographic images with accurate correlation between them. Also it can provide simultaneous multimodal imaging of retinal pathologies, such as fluorescein and indocyanine green angiographies, infrared and blue reflectance (red-free) images, fundus autofluorescence images, and OCT scans (Spectralis HRA + OCT; Heidelberg Engineering, Heidelberg, Germany). The combination of various macular diagnostic tools can lead to a better understanding and improved knowledge of macular diseases.

Choroidal abnormalities detected by near-infrared reflectance imaging as a new diagnostic criterion for neurofibromatosis 1

OBJECTIVE

To investigate in a large sample of consecutive patients with neurofibromatosis type 1 (NF1) the possibility of including the presence of choroidal abnormalities detected by near-infrared reflectance (NIR) as a new diagnostic criterion for NF1.

DESIGN

Cross-sectional evaluation of a diagnostic test.

PARTICIPANTS AND CONTROLS

Ninety-five consecutive adult and pediatric patients (190 eyes) with NF1, diagnosed based on the National Institutes of Health (NIH) criteria. Controls included 100 healthy age- and gender-matched control subjects.

METHODS

Confocal scanning laser ophthalmoscopy was performed for each subject, investigating the presence and the number of choroidal abnormalities.

MAIN OUTCOME MEASURES

Sensitivity, specificity, and diagnostic accuracy for the different cutoff values of the criterion choroidal nodules detected by NIR compared with the NIH criteria.

RESULTS

Choroidal nodules detected by NIR imaging were present in 79 (82%) of 95 of the NF1 patients, including 15 (71%) of the 21 NF1 pediatric patients. Similar abnormalities were present in 7 (7%) of 100 healthy subjects, including 2 (8%) of the 25 healthy pediatric subjects. The highest accuracy was obtained at the cutoff value of 1.5 choroidal nodules detected by NIR imagery. Sensitivity and specificity of the examination at the optimal cutoff point were 83% and 96%, respectively. Diagnostic accuracy was 90% in the overall population and 83% in the pediatric population. Both of these values were in line with the most common NIH diagnostic criteria.

CONCLUSIONS

Choroidal abnormalities appearing as bright patchy nodules detected by NIR imaging frequently occurred in NF1 patients. The present study shows that NIR examination to detect choroidal involvement should be considered as a new diagnostic criterion for NF1.

Monthly ranibizumab for choroidal neovascularizations secondary to angioid streaks in pseudoxanthoma elasticum: a one-year prospective study

PURPOSE

To evaluate the efficacy and safety of monthly intravitreal ranibizumab for the treatment of choroidal neovascularizations (CNV) secondary to angioid streaks (AS) in pseudoxanthoma elasticum (PXE).

DESIGN

Twelve-month prospective, open-label, uncontrolled, nonrandomized interventional clinical trial.

METHODS

In 7 patients, 1 eye with an active CNV was injected with 0.5 mg ranibizumab monthly over 1 year. Distance and reading visual acuity, reading speed, angiographic findings, and central retinal thickness (CRT) on optical coherence tomography were assessed at each visit. Central retinal light increment sensitivity (LIS) was assessed by microperimetry at baseline, at 6 months, and 3 to 4 months after the last injection.

RESULTS

Best-corrected visual acuity increased significantly from baseline to month 12 (20/63 or 61 ETDRS letters to 20/32 or 73 ETDRS letters; P = .012). The effect was maintained 3 months later (61 ETDRS letters to 72 ETDRS letters; P = .055). Reading acuity and speed could be maintained throughout the study. Central LIS improved (6.6 dB, SD ± 5.9 at baseline to 7.4 dB, SD ± 6.2 at last follow-up; P < .001). Leakage from active CNVs subsided. Mean change in CRT from baseline to month 12 and 15 was -86 μm (P = .074) and -65 μm (P = .182), respectively. No serious adverse events occurred.

CONCLUSIONS

Efficacy outcomes indicate a beneficial therapeutic effect of intravitreal ranibizumab on central visual function including retinal LIS. Both the functional and morphologic response based on angiographic and OCT findings to ranibizumab treatment implicate an important pathophysiological role of vascular endothelial growth factor in CNVs secondary to AS in PXE. Intravitreal ranibizumab appears to be a safe and efficacious treatment in these patients.

High-resolution optical coherence tomography retinal imaging: a case series illustrating potential and limitations

Purpose. To present a series of retinal disease cases that were imaged by spectral domain optical coherence tomography (SD-OCT) in order to illustrate the potential and limitations of this new imaging modality. Methods. The series comprised four selected cases (one case each) of age-related macular degeneration (ARMD), diabetic retinopathy (DR), central retinal artery occlusion (CRAO), and branch retinal vein occlusion (BRVO). Patients were imaged using the Heidelberg Spectralis (Heidelberg Engineering, Germany) in SD-OCT mode. Patients also underwent digital fundus photography and clinical assessment. Results. SD-OCT imaging of a case of age-related macular degeneration revealed a subfoveal choroidal neovascular membrane with detachment of the retinal pigment epithelium (RPE) and neurosensory retina. Using SD-OCT, the cases of DR and BRVO both exhibited macular edema with cystoid spaces visible in the outer retina. Conclusions. The ability of SD-OCT to clearly and objectively elucidate subtle morphological changes within the retinal layers provides information that can be used to formulate diagnoses with greater confidence.

Imaging geographic atrophy in age-related macular degeneration

Advances in retinal imaging technology have largely contributed to the understanding of the natural history, prognostic markers and disease mechanisms of geographic atrophy (GA) due to age-related macular degeneration. There is still no therapy available to halt or slow the disease process. In order to evaluate potential therapeutic effects in interventional trials, there is a need for precise quantification of the GA progression rate. Fundus autofluorescence imaging allows for accurate identification and segmentation of atrophic areas and currently represents the gold standard for evaluating progressive GA enlargement. By means of high-resolution spectral-domain optical coherence tomography, distinct microstructural alterations related to GA can be visualized.

High-resolution spectral domain optical coherence tomography and fundus autofluorescence correlation in tubercular serpiginouslike choroiditis

Objective

This study aims to describe changes in high-resolution spectral domain optical coherence tomography (SD-OCT) scans with simultaneous fundus autoflorescence (FAF) signals in tubercular serpiginouslike choroiditis (SLC).

Methods

Simultaneous SD-OCT and FAF imaging of eyes affected with SLC from acute stage until resolution of lesions was obtained using Spectralis HRA+OCT system (Heidelberg Engineering, Heidelberg, Germany).

Patients

Four eyes (three patients) with SLC were prospectively followed.

Results

Acute lesions of SLC (diffusely hyperautofluorescent) corresponded to hyperreflective areas on SD-OCT involving the retinal pigment epithelium (RPE), photoreceptor outer segment tips (POST), inner segment–outer segment (IS/OS) junction, external limiting membrane (ELM), and outer nuclear layer (ONL) with a minimal distortion of inner retinal layers. There was no backscattering from inner choroid. During healing, lesions became discrete with a hypoautofluorescent border and predominant hyperautofluorescence centrally. The hyperreflective fuzzy areas on SD-OCT scans disappeared, and irregular, knobbly elevations of outer retinal layers appeared. The RPE, POST, IS/OS junction, and ELM could not be distinguished. The ONL appeared normal. The choroid showed an increased reflectance. As the lesions healed further over the next 3–6 months, they became predominantly hypoautofluorescent with loss of RPE, POST, IS/OS junction, and ELM in SD-OCT scan.

Conclusion

The SD-OCT provided an insight into the ultrastructural changes in the outer retina during the course of acute SLC lesions. The changes on OCT correlated with abnormal FAF findings.

Fundus autofluorescence and spectral-domain optical coherence tomography characteristics in a rapidly progressing form of geographic atrophy

PURPOSE

To further characterize a previously described phenotypic variant of geographic atrophy (GA) associated with rapid progression and a diffuse-trickling appearance on fundus autofluorescence (FAF).

METHODS

Thirty-six patients (60 eyes; 72.2% women; mean age, 69.4 ± 10.7 years) with this distinct phenotype were examined by simultaneous confocal scanning laser ophthalmoscopy (cSLO) and spectral-domain optical coherence tomography (SD-OCT) imaging. Images were qualitatively and quantitatively analyzed and compared with 60 eyes (38 patients) with non diffuse-trickling GA.

RESULTS

The atrophic area in the diffuse-trickling phenotype showed a grayish FAF signal and characteristic coalescent lobular configuration at the lesion boundaries. SD-OCT revealed a marked splitting of band 4 (the presumptive retinal pigment epithelium (RPE)/Bruch's membrane (BM) complex) in all 240 analyzed border sections of diffuse-trickling GA eyes (four borders/eye) with a mean distance between the inner and outer parts of band 4 of 23.2 ± 7.5 μm. This finding was present in only 13.8% (33/240) of analyzed border sections in non diffuse-trickling GA.

CONCLUSIONS

Patients with the rapidly progressing diffuse-trickling GA phenotype exhibited a characteristic marked separation within the RPE/BM complex on SD-OCT-imaging. The presumed histopathologic correlates are basal laminar deposits. Such deposits may promote RPE cell death and, thus, contribute to rapid GA progression. The persistence of these deposits within the atrophic lesion may account for the distinct grayish FAF appearance, which differs from the markedly reduced signal in other forms of GA. Identification of such alterations based on FAF and SD-OCT imaging may be helpful in future interventional trials directed toward slowing GA progression. (ClinicalTrials.gov number, NCT00393692.).

Neovascular age-related macular degeneration: opportunities for development of first-in-class biopharmaceuticals

Age-related macular degeneration (AMD) is a condition that may cause blindness. The prevalence of the disease in the Western world is estimated at 1-2% of the population. Over the past decade, treatment of neovascular AMD has been shifting from destruction of newly formed blood vessels towards inhibitors that silence the vascular endothelial growth factor (VEGF) pathway. Such agents are often first-in-class biopharmaceuticals that benefit from the fact that they can be locally administered in an immune-privileged environment with slow clearance. These new VEGF pathway inhibitors have improved therapeutic effects over conventional treatment and have promoted the identification of novel targets for inhibition of AMD angiogenesis. This review describes the rationale behind the shift from conventional to current treatment options and discusses investigational, most notably biopharmaceutical, drugs that are in clinical trials. It also provides possible points for improvement of these treatments, specifically regarding their delivery.

Optical coherence tomography-current technology and applications in clinical and biomedical research

Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. By mapping the local reflectivity, OCT visualizes the morphology of the sample. In addition, functional properties such as birefringence, motion, or the distributions of certain substances can be detected with high spatial resolution. Its main field of application is biomedical imaging and diagnostics. In ophthalmology, OCT is accepted as a clinical standard for diagnosing and monitoring the treatment of a number of retinal diseases, and OCT is becoming an important instrument for clinical cardiology. New applications are emerging in various medical fields, such as early-stage cancer detection, surgical guidance, and the early diagnosis of musculoskeletal diseases. OCT has also proven its value as a tool for developmental biology. The number of companies involved in manufacturing OCT systems has increased substantially during the last few years (especially due to its success in opthalmology), and this technology can be expected to continue to spread into various fields of application.

Monthly ranibizumab for nonproliferative macular telangiectasia type 2: a 12-month prospective study

PURPOSE

To investigate the efficacy and safety of intravitreal ranibizumab for the treatment of nonproliferative macular telangiectasia (MacTel) type 2.

DESIGN

Prospective, open-label, uncontrolled, nonrandomized interventional clinical trial.

METHODS

One eye (disease stage 2 or 3) of each patient (n = 10) with nonproliferative MacTel type 2 was injected with 0.5 mg ranibizumab at monthly intervals for one year. Visual acuity, angiographic findings, and retinal thickness were assessed at each visit. The primary endpoint was the change in best-corrected distance visual acuity after one year compared to baseline.

RESULTS

Mean visual acuity showed a transient increase in the study eye. However, after 12 months of treatment there was no significant change of visual acuity compared to baseline or compared to the fellow eye. Fluorescein angiography revealed a decrease of telangiectatic-appearing capillaries and of late-phase leakage, which was accompanied by a topographically related significant reduction in macular thickness. Three to 5 months after the last treatment, angiographic appearance and retinal thickness were similar to baseline. In one patient, the last intravitreal injection was not performed because of safety concerns after a transitory ischemic attack. Otherwise, no serious adverse events were observed.

CONCLUSIONS

The angiographic and tomographic effects after intravitreal inhibition of vascular endothelial growth factor (VEGF) using ranibizumab implicate a pathophysiological role of the VEGF pathway in nonproliferative MacTel type 2. As the morphologic response was not associated with a clear functional benefit, and because of the transient nature of the treatment effect, monthly intravitreal ranibizumab is not recommended for the nonproliferative disease stage of MacTel type 2.

Structure-function correlation of the human central retina

Background

The impact of retinal pathology detected by high-resolution imaging on vision remains largely unexplored. Therefore, the aim of the study was to achieve high-resolution structure-function correlation of the human macula in vivo.

Methodology/Principal Findings

To obtain high-resolution tomographic and topographic images of the macula spectral-domain optical coherence tomography (SD-OCT) and confocal scanning laser ophthalmoscopy (cSLO), respectively, were used. Functional mapping of the macula was obtained by using fundus-controlled microperimetry. Custom software allowed for co-registration of the fundus mapped microperimetry coordinates with both SD-OCT and cSLO datasets. The method was applied in a cross-sectional observational study of retinal diseases and in a clinical trial investigating the effectiveness of intravitreal ranibizumab in macular telangietasia type 2. There was a significant relationship between outer retinal thickness and retinal sensitivity (p<0.001) and neurodegeneration leaving less than about 50 µm of parafoveal outer retinal thickness completely abolished light sensitivity. In contrast, functional preservation was found if neurodegeneration spared the photoreceptors, but caused quite extensive disruption of the inner retina. Longitudinal data revealed that small lesions affecting the photoreceptor layer typically precede functional detection but later cause severe loss of light sensitivity. Ranibizumab was shown to be ineffective to prevent such functional loss in macular telangietasia type 2.

Conclusions/Significance

Since there is a general need for efficient monitoring of the effectiveness of therapy in neurodegenerative diseases of the retina and since SD-OCT imaging is becoming more widely available, surrogate endpoints derived from such structure-function correlation may become highly relevant in future clinical trials.