Classification of abnormal fundus autofluorescence patterns in the junctional zone of geographic atrophy in patients with age related macular degeneration

Spectral domain optical coherence tomography-determined morphologic predictors of age-related macular degeneration-associated geographic atrophy progression

PURPOSE

To correlate spectral domain optical coherence tomography (SD OCT)-determined morphologic alterations in eyes with geographic atrophy because of age-related macular degeneration with lesion size, enlargement rate, and the presence of multifocal patches of atrophy.

METHODS

Forty-three eyes of 43 patients with age-related macular degeneration-associated geographic atrophy were visualized by SD OCT and fundus autofluorescence imaging. The baseline area of geographic atrophy and enlargement rates over at least 24 weeks were calculated from the fundus autofluorescence images. The mean and median follow-up times were 47.4 and 48 weeks, respectively. Morphologic alterations were evaluated in the baseline SD OCT images. Ninety-seven SD OCT scans per eye were graded and included in the analysis. Correlations between morphologic alterations and the rate of lesion enlargement, size, and focality, and the diffuse trickling fundus autofluorescence pattern were determined.

RESULTS

The mean and median enlargement rates were 2.07 mm(2)/year (n = 43; SD, 1.30) and 2.02 mm(2)/year, respectively. Outer retinal tubulations (P = 0.003) and irregular elevations of the retinal pigment epithelium/Bruch membrane complex (P < 0.001) in the atrophic region, and splitting of the retinal pigment epithelium/Bruch membrane complex at 2 junctional zone borders (P = 0.02) correlated with faster enlargement. Outer retinal tubulations (P = 0.096), irregular elevations of the retinal pigment epithelium/Bruch membrane complex (P = 0.010), and crown-like elevations with debris beneath in the atrophic region (P = 0.063) correlated with larger lesion size. Hyperreflective plaques in the outer retina appeared more frequently in eyes with multifocal patches of atrophy (P = 0.005).

CONCLUSION

Distinct morphologic alterations visible on SD OCT imaging in eyes with geographic atrophy because of age-related macular degeneration are associated with faster enlargement rates, larger lesion size, and multifocal patches of atrophy.

Predictors for the progression of geographic atrophy in patients with age-related macular degeneration: fundus autofluorescence study with modified fundus camera

PURPOSE

We examined the association between abnormal fundus autofluorescence (FAF) features on images obtained by a modified fundus camera (mFC) and geographic atrophy (GA) progression in patients with age-related macular degeneration (AMD).

METHODS

Serial FAF images of 131 eyes from 131 patients with GA were included in the study. All FAF images were obtained with an mFC (excitation, ∼ 500-610 nm; emission, ∼ 675-715 nm). The GA area was quantified at baseline and 1 year later using a customized segmentation program. The yearly GA enlargement rate was then calculated. Abnormal FAF patterns in the junctional zone of GA were classified as None or Minimal change, Focal, Patchy, Banded, or Diffuse according to previously published classification based on confocal scanning laser ophthalmoscopy (cSLO). The relationship between GA enlargement and abnormal FAF was evaluated.

RESULTS

The mean rate of GA enlargement was the fastest in eyes with Diffuse pattern (1.74 mm(2) per year), followed by eyes with the Banded pattern (1.69 mm(2) per year). Binary logistic regression analysis revealed that eyes with the Banded and Diffuse pattern had significantly higher risk for GA enlargement compared with eyes with the other patterns.

CONCLUSIONS

FAF image obtained by mFC appears to be acceptable for evaluating GA in accordance with an established cSLO-based classification. Eyes with the Banded or the Diffuse patterns of abnormal FAF at baseline indicate a high risk for GA progression. Identifying patients at high risk for GA progression using an mFC is broadly available method that can provide additional information to help predict disease course.

Quantitative fundus autofluorescence in healthy eyes

PURPOSE

Fundus autofluorescence was quantified (qAF) in subjects with healthy retinae using a standardized approach. The objective was to establish normative data and identify factors that influence the accumulation of RPE lipofuscin and/or modulate the observed AF signal in fundus images.

METHODS

AF images were acquired from 277 healthy subjects (age range: 5-60 years) by employing a Spectralis confocal scanning laser ophthalmoscope (cSLO; 488-nm excitation; 30°) equipped with an internal fluorescent reference. For each image, mean gray level was calculated as the average of eight preset regions, and was calibrated to the reference, zero-laser light, magnification, and optical media density from normative data on lens transmission spectra. Relationships between qAF and age, sex, race/ethnicity, eye color, refraction/axial length, and smoking status were evaluated as was measurement repeatability and the qAF spatial distribution.

RESULTS

qAF levels exhibited a significant increase with age. qAF increased with increasing eccentricity up to 10° to 15° from the fovea and was highest superotemporally. qAF values were significantly greater in females, and, compared with Hispanics, qAF was significantly higher in whites and lower in blacks and Asians. No associations with axial length and smoking were observed. For two operators, between-session repeatability was ± 9% and ± 12%. Agreement between the operators was ± 13%.

CONCLUSIONS

Normative qAF data are a reference tool essential to the interpretation of qAF measurements in ocular disease.

Fundus autofluorescence imaging in age-related macular degeneration

Fundus autofluorescence (FAF) is a noninvasive imaging technology that provides information on the distribution of lipofuscin within the retinal pigment epithelial cells. Progressive accumulation of lipofuscin within retinal pigment epithelial cells is involved in the pathogenesis of age-related macular degeneration (AMD). Fundus autofluorescence imaging using a confocal scanning laser ophthalmoscope is a useful technique to identify high-risk characteristics in patients with nonexudative AMD. It gives also some valuable knowledge and clues in differantial diagnosis of exudative age-related macular degeneration. This review comprises an introduction to fundus autofluorescence, a review of FAF imaging in AMD, and the recent classification of geographic atrophy (GA) and early AMD phenotypes by the Fundus Autofluorescence in Age-related Macular Degeneration Study. The association of phenotype and atrophy progression and choroidal neovascularization development are also summarized.

Methods and reproducibility of grading optimized digital color fundus photographs in the Age-Related Eye Disease Study 2 (AREDS2 Report Number 2)

PURPOSE

To establish continuity with the grading procedures and outcomes from the historical data of the Age-Related Eye Disease Study (AREDS), color photographic imaging and evaluation procedures for the assessment of age-related macular degeneration (AMD) were modified for digital imaging in the AREDS2. The reproducibility of the grading of index AMD lesion components and for the AREDS severity scale was tested at the AREDS2 reading center.

METHODS

Digital color stereoscopic fundus photographs from 4203 AREDS2 subjects collected at baseline and annual follow-up visits were optimized for tonal balance and graded according to a standard protocol slightly modified from AREDS. The reproducibility of digital grading of AREDS2 images was assessed by reproducibility exercises, temporal drift (regrading a subset of baseline annually, n = 88), and contemporaneous masked regrading (ongoing, monthly regrade on 5% of submissions, n = 1335 eyes).

RESULTS

In AREDS2, 91% and 96% of images received replicate grades within two steps of the baseline value on the AREDS severity scale for temporal drift and contemporaneous assessment, respectively (weighted Kappa of 0.73 and 0.76). Historical data for temporal drift in replicate gradings on the AREDS film-based images were 88% within two steps (weighted Kappa = 0.88). There was no difference in AREDS2-AREDS concordance for temporal drift (exact P = 0.57).

CONCLUSIONS

Digital color grading has nearly the same reproducibility as historical film grading. There is substantial agreement for testing the predictive utility of the AREDS severity scale in AREDS2 as a clinical trial outcome. (ClinicalTrials.gov number, NCT00345176.)

Investigation of oral fenretinide for treatment of geographic atrophy in age-related macular degeneration

BACKGROUND

Excessive accumulation of retinol-based toxins has been implicated in the pathogenesis of geographic atrophy (GA). Fenretinide, an orally available drug that reduces retinol delivery to the eye through antagonism of serum retinol-binding protein (RBP), was used in a 2-year trial to determine whether retinol reduction would be effective in the management of geographic atrophy.

METHODS

The efficacy of fenretinide (100 and 300 mg daily, orally) to slow lesion growth in geographic atrophy patients was examined in a 2-year, placebo-controlled double-masked trial that enrolled 246 patients at 30 clinical sites in the United States.

RESULTS

Fenretinide treatment produced dose-dependent reversible reductions in serum RBP-retinol that were associated with trends in reduced lesion growth rates. Patients in the 300 mg group who achieved serum retinol levels of ≤ 1 μM (≤ 2 mg/dL RBP) showed a mean reduction of 0.33 mm in the yearly lesion growth rate compared with subjects in the placebo group (1.70 mm/year vs. 2.03 mm/year, respectively, P = 0.1848). Retinol-binding protein reductions <2 mg/dL correlated with further reductions in lesion growth rates (r = 0.478). Fenretinide treatment also reduced the incidence of choroidal neovascularization (approximately 45% reduction in incidence rate in the combined fenretinide groups vs. placebo, P = 0.0606). This therapeutic effect was not dose dependent and is consistent with anti-angiogenic properties of fenretinide, which have been observed in other disease states.

CONCLUSION

The findings of this study and the established safety profile of fenretinide in chronic dosing regimens warrant further study of fenretinide in the treatment of geographic atrophy.

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

PURPOSE

To characterize peripheral fundus autofluorescence (FAF) abnormalities in patients with age-related macular degeneration (AMD), correlate these with clinical findings, and identify risk factors associated with these FAF abnormalities.

DESIGN

Clinic-based, cross-sectional study.

PARTICIPANTS

A total of 119 consecutive patients: 100 patients with AMD (200 eyes) and 19 patients without AMD (38 eyes).

METHODS

In a prospective study performed at the Doheny Eye Institute, University of Southern California, widefield 200-degree FAF and color images were obtained by the Optos 200Tx Ultra-Widefield device (Optos, Dunfermline, Scotland) using a standardized imaging protocol. The FAF images were captured centered on the fovea, and additional images were captured after steering the field of view inferiorly and superiorly. All FAF and color images were graded independently by 2 masked ophthalmologists with respect to the presence, location, extent, and type of peripheral (defined as outside the central 30 degrees) FAF abnormality.

MAIN OUTCOME MEASURES

Presence and type of peripheral FAF abnormalities.

RESULTS

Peripheral FAF abnormalities were evident in 164 eyes (68.9%), with several distinct FAF patterns identified: granular (46.2%), mottled (34.0%), and nummular (18.1%). A 90% concordance of FAF patterns was observed between both eyes. Abnormal FAF occurred more frequently in neovascular compared with non-neovascular AMD or normal eyes (86% vs. 72.8% vs. 18.4%, respectively, P<0.001). Significant risk factors for peripheral FAF abnormalities were AMD type (neovascular AMD odds ratio [OR], 12.7 and non-neovascular AMD OR, 6.2 compared with normal eyes, P<0.001), older age (OR, 6.5; 95% confidence interval [CI], 2.4-17.8; P<0.001 for the oldest quartile compared with the youngest), and female sex (OR, 4.1; 95% CI, 1.9-8.9; P<0.001). Clinical features on color photography were detected in 174 eyes (73.1%): peripheral drusen (51.7%), retinal pigment epithelium (RPE) depigmentation (34.9%), RPE hyperpigmentation (branching reticular pigmentation) (22.7%), and atrophic patches (16.8%). There was a high correlation between specific FAF and clinical findings: granular FAF with peripheral drusen (P<0.001) and mottled FAF with RPE depigmentation (P<0.001).

CONCLUSIONS

Several distinct patterns of peripheral FAF abnormalities were observed in 68.9% of patients, with AMD type, female sex, and age being independent risk factors. The peripheral FAF patterns correlate strongly with specific clinical features seen in eyes with AMD.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Histologic basis of variations in retinal pigment epithelium autofluorescence in eyes with geographic atrophy

PURPOSE

Lipofuscin contained in the retinal pigment epithelium (RPE) is the main source of fundus autofluorescence (FAF), the target of an imaging method useful for estimating the progression of geographic atrophy (GA) in clinical trials. To establish a cellular basis for hyperfluorescent GA border zones, histologic autofluorescence (HAF) was measured at defined stages of RPE pathologic progression.

DESIGN

Experimental study.

PARTICIPANTS AND CONTROLS

Ten GA donor eyes (mean age ± standard deviation, 87.1 ± 4.0 years) and 3 age-matched control eyes (mean age ± standard deviation, 84.0 ± 7.2 years) without GA.

METHODS

The 10-micrometer-thick sections were divided into zones of RPE morphologic features according to an 8-point scale. Any HAF excited by 488 nm light was imaged by laser confocal microscopy. The HAF intensity summed along vertical lines perpendicular to Bruch's membrane at 0.2-μm intervals served as a surrogate for FAF. Intensity profiles in 151 zones were normalized to grade 0 at a standard reference location in each eye. Cross-sectional area, mean, and sum autofluorescence for individual RPE cells were measured (cellular autofluorescence [CAF]).

MAIN OUTCOME MEASURES

Statistically significant differences in intensity and localization of HAF and CAF at defined stages of RPE morphologic progression for GA and control eyes.

RESULTS

The RPE morphologic features were most abnormal (cell rounding, sloughing, and layering; grade 2) and HAF intensity profiles were highest and most variable immediately adjacent to atrophic areas. Peaks in HAF intensity frequently were associated with vertically superimposed cells. The HAF value that optimally separated reactive RPE was 0.66 standard deviations more than the mean for uninvolved RPE and was associated with a sensitivity of 75.8% and a specificity of 76.3%. When variable cell area was accounted for, neither mean nor sum CAF differed significantly among the RPE pathologic grades.

CONCLUSIONS

Areas with advanced RPE alterations are most likely to exhibit clinically recognizable patterns of elevated FAF around GA, but may not predict cells about to die, because of vertically superimposed cells and cellular fragments. These data do not support a role for lipofuscin-related cell death and call into question the rationale of treatments targeting lipofuscin.

Comparison of color fundus photographs and fundus autofluorescence images in measuring geographic atrophy area

PURPOSE

To assess the agreement between color fundus photographs (CFP) and fundus autofluorescence (FAF) images when measuring geographic atrophy (GA) area and reproducibility of measurements between graders. Frequency and disagreement types were also determined.

METHODS

Eyes with GA secondary to age-related macular degeneration had CFP and FAF imaging on the same day. Seventy-two eyes from 72 patients were included in the analysis. Three graders calculated GA area using digital imaging software. Main outcome measures included agreement between graders for GA area on both FAF and CFP and agreement between both imaging modalities.

RESULTS

The intraclass correlation for the 3 graders for FAF images was 0.99 (95% confidence interval, 0.98-0.99). For CFP, it was 0.96 (95% confidence interval, 0.94-0.97). The intraclass correlation between imaging modalities for Graders 1, 2, and 3 were 0.93, 0.85, and 0.87, respectively. Sensitivities to detect involvement of fovea (CFP, 86-97%; FAF, 72-93%) and specificities to detect sparing of fovea (CFP, 74-76%; FAF, 59-88%) overlapped between imaging modalities.

CONCLUSION

Both CFP and FAF imaging are reliable for measuring GA area. Interobserver agreement was slightly higher for FAF images. Although the high agreement between modalities suggests that either would be appropriate for measuring GA area, using both may be the best approach for following GA progression.

Age-related macular degeneration revisited--piecing the puzzle: the LXIX Edward Jackson memorial lecture

PURPOSE

To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD.

DESIGN

Review of published clinical and experimental studies.

METHODS

Analysis and synthesis of clinical and experimental data.

RESULTS

We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors.

CONCLUSIONS

Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.

Effects of coagulation on the autofluorescence pattern of ARPE-19 cells: an in vitro study

OBJECTIVE

Changes in fundus autofluorescence (AF) are observed in various retinal disorders. Lipofuscin accumulation within the retinal pigment epithelium (RPE) is a source of fundus AF (FAF); however, the causes of short-term increases in FAF observed in inflammatory conditions or after laser treatment are unknown. Here, we describe an RPE cell culture model that is useful for investigations of FAF.

METHODS

ARPE-19 cells were cultured in 2-well chamber slides. Cells were exposed to isolated rabbit photoreceptor outer segments (POS) to mimic in vivo phagocytic activity. The AF of RPE cells exposed to POS was measured before and after focal coagulation of the cultures. AF was measured over a period of 4 weeks. Cell lysates were examined by two-dimensional (2D) gel electrophoresis and mass spectrometry analysis.

RESULTS

The exposure of ARPE cells to POS did not lead to increased AF; however, after coagulation, cells exposed to POS showed a statistically significant increase in AF (p < 0.05). 2D electrophoresis of the cell lysates revealed changes in 3 proteins. One of these proteins, identified by mass spectrometry as ezrin-radixin-moesin-binding phosphoprotein 50, was reduced in the coagulated cell population.

CONCLUSIONS

We have established an in vitro model of RPE cells in culture that can be used to evaluate the development of AF and changes in cellular proteins that accompany laser photocoagulation.

Peripheral autofluorescence findings in age-related macular degeneration

PURPOSE

To describe the peripheral autofluorescent findings in patients with age-related macular degeneration (AMD) using ultrawide-field imaging.

METHODS

We retrospectively reviewed the ultra-wide-field autofluorescent images of all patients diagnosed with AMD or macular drusen at the Department of Ophthalmology of Weill Cornell Medical College from July 2010 to September 2011. Peripheral autofluorescent phenotypes included normal autofluorescence, focal pinpoint hyperfluorescence, granular fluorescent changes, patchy hypofluorescence, and reticular hypofluorescence.

RESULTS

One hundred and ten consecutive patients (220 eyes) with a diagnosis of AMD or macular drusen were imaged using ultra-wide-field autofluorescent technology during the study period. Eighty-three patients (157 eyes) were included in the final analysis. Peripheral autofluorescent abnormalities were present in 63.6% of eyes with AMD versus 35.7% of control eyes (p=0.049). Granular fluorescent changes (p=0.0001) and patchy hypofluorescence (p=0.0015) were more common in eyes with advanced AMD than in eyes with early AMD or control eyes. Granular fluorescent changes were also more common in eyes with choroidal neovascularization (p=0.026) or geographic atrophy (p=0.0001). Patchy hypofluorescence (0.0001) was more common in eyes with geographic atrophy.

CONCLUSIONS

Peripheral autofluorescent abnormalities are common in eyes with AMD. The peripheral findings in eyes with AMD may represent different phenotypes, which may indicate different environmental or genetic factors in the development of AMD. Characterizing the different peripheral phenotypes may have implications for diagnosis and treatment of AMD subtypes.

Intra and interobserver agreement in the classification of fundus autofluorescence patterns in geographic atrophy secondary to age-related macular degeneration

BACKGROUND

To describe the intra and interobserver agreement in the evaluation of fundus autofluorescence patterns in geographic atrophy secondary to age-related macular degeneration.

METHODS

A consecutive series of patients with geographic atrophy and fundus autofluorescence images of a minimum acceptable quality for grading were included. Four observers with experience in the evaluation of autofluorescence images independently classified the randomly presented series of images on two occasions, at least 1 month apart from each other (intraobserver analysis). The second determination of each observer was used for evaluation of interobserver agreement. The kappa statistic and 95% confidence intervals, together with percentages of agreement, were used to analyze the results.

RESULTS

The final sample included 69 eyes of 49 patients. Intraobserver agreement ranged from substantial to almost perfect (kappa between 0.51 and 0.83), while interobserver results ranged from poor to substantial (corresponding to kappa between 0.30 and 0.62). The use of more simple classifications improved reproducibility.

CONCLUSIONS

Although intraobserver reproducibility was high, interobserver agreement was variable. Clear descriptions and a uniform set of criteria to classify these patients are needed if fundus autofluorescence imaging is used to evaluate patients with geographic atrophy.

Fundus autofluorescence imaging in age-related macular degeneration and geographic atrophy

The traditional method for documenting and quantifying geographic atrophy (GA) is color photography. This method has been shown to be reproducible in several clinical trials, including the Age-related Eye Disease Study (AREDS) and the natural progression of GA studies by Sunness et al. (AREDS No. 6, Am J Ophthalmol 132(5):668-681, 2001; Sunness et al., Invest Ophthalmol Vis Sci 40(8):1761-1769, 1999). Nevertheless, it can be difficult to distinguish between dead/nonfunctioning retinal pigment epithelium (RPE), living but depigmented RPE (RPE often release melanin granules upon injury), and yellowish coloration caused by large drusen or calcified regressed drusen. Two imaging technologies that seem promising are fundus autofluorescence (FAF) and spectral domain (high resolution) optical coherence tomography (SDOCT). Here we provide an overview of FAF imaging in the setting of age-related macular degeneration (AMD) and GA.

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.

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.).

Fundus autofluorescence in geographic atrophy: a review

Fundus autofluorescence is a noninvasive imaging technology that provides information on the distribution of lipofuscin within the retinal pigment epithelial cell monolayer. Progressive accumulation of lipofuscin within retinal pigment epithelial cells is involved in the pathogenesis of geographic atrophy in age-related macular degeneration. This review contains an introduction to fundus autofluorescence, review of currently available imaging methods, and discussion of the role of autofluorescence imaging in geographic atrophy progression. The recent classification of geographic atrophy phenotypes by the Fundus Autofluorescence in Age-related Macular Degeneration Study (FAM) and the association of phenotype and atrophy progression are also summarized.

Use of fundus autofluorescence images to predict geographic atrophy progression

PURPOSE

Fundus autofluorescence imaging has been shown to be helpful in predicting progression of geographic atrophy (GA) secondary to age-related macular degeneration. We assess the ability of fundus autofluorescence imaging to predict rate of GA progression using a simple categorical scheme.

METHODS

Subjects with GA secondary to age-related macular degeneration with fundus autofluorescence imaging acquired at least 12 months apart were included. Rim area focal hyperautofluorescence was defined as percentage of the 500-μm-wide margin bordering the GA that contained increased autofluorescence. Rim area focal hyperautofluorescence on baseline fundus autofluorescence images was assessed and categorized depending on the extent of rim area focal hyperautofluorescence (Category 1: ≤33%; Category 2: between 33 and 67%; Category 3: ≥67%). Total GA areas at baseline and follow-up were measured to calculate change in GA progression.

RESULTS

Forty-five eyes of 45 subjects were included; average duration of follow-up was 18.5 months. Median growth rates differed among categories of baseline rim area focal hyperautofluorescence (P = 0.01 among Categories 1, 2, and 3; P = 0.008 for Category 1 compared with Category 3, Jonckheere-Terpstra test).

CONCLUSION

A simple categorical scheme that stratifies the amount of increased autofluorescence in the 500-μm margin bordering GA may be used to differentiate faster and slower progressors.

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

PURPOSE

To evaluate the clinical relevance of a new diagnostic modality, simultaneous confocal scanning laser ophthalmoscopy (cSLO) and high-speed, high-resolution, spectral-domain optical coherence tomography (OCT), for the visualization of macular pathologies.

METHODS

OCT images and simultaneous recording of fluorescein angiography, indocyanine green (ICG) angiography, infrared, and blue reflectance ('red-free') or fundus autofluorecence (FAF) images were obtained with a novel imaging device (Spectralis HRA + OCT; Heidelberg Engineering, Heidelberg, Germany). An optically pumped solid-state laser generated the excitation wavelength (488 nm) required for blue reflectance, FAF and fluorescein angiography images. For ICG angiography and infrared imaging, diode laser sources at 790 and 815 nm were used. For OCT, 40 000 A-scans per second were acquired with 7 μm axial and 14 μm lateral optical resolution. The B-scans covering a transversal range of 30° had a scan width up to 1.536 A-scans with a digital lateral resolution of 5 μm/pixel, a scan depth of 1.8 mm with 3.5 μm/pixel digital axial resolution and a scan rate of up to 48 B-scans/second. In addition, volume scans could be obtained at 15, 20 and 30° fields of view. An integrated eye tracking allowed for live averaging of cSLO images as well as OCT B-scans.

RESULTS

Early, neovascular and atrophic age-related macular degeneration, macular telangiectasia, retinal arterial, branch vein occlusion and other pathologies were imaged, and cSLO and OCT frames correlated. Fluorescein and ICG angiographic phenomena recorded in cSLO images could be analysed accurately in corresponding OCT cross-sections. Abnormal FAF signals were correlated to alterations at the outer retinal/retinal pigment epithelial cell layer in high-resolution OCT scans. Three-dimensional OCT enabled comprehensive retinal coverage. The imaging software tracked eye movements accurately. Averaging of live B-scans enhanced image quality considerably.

CONCLUSION

  The combined cSLO/OCT system allowed for simultaneous recordings of topographic and tomographic images with accurate correlation between the confocal angiograms, FAF images as well as other imaging modes with the OCT scans. The instrument thus provides simultaneous multi-modal imaging of retinal pathologies and disease.

Quantification of retinal pigment epithelial phenotypic variation using laser scanning cytometry

PURPOSE

Quantifying phenotypic variation at the level of protein expression (variegation) within populations of retinal pigment epithelium (RPE) cells may be important in the study of pathologies associated with this variation. The lack of quantitative methods for examining single cells, however, and the variable presence of pigment and/or lipofuscin complicate this experimental goal. We have applied the technique of laser scanning cytometry (LSC) to paraffin sections of mouse and human eyes to evaluate the utility of LSC for these measurements.

METHODS

Mouse eyes were perfusion fixed in 4% paraformaldehyde and embedded in paraffin. Postmortem human eyes were fixed and dissected to obtain a 9-mm punch, which was then embedded in paraffin. A laser scanning cytometer equipped with violet, argon, and helium-neon lasers and the detectors for blue, green, and long red were used to record the fluorescence of each individual cell at all three wavelengths. Raw data were recorded and processed using the WinCyte software. Individual nuclei were identified by the fluorescence of the 4',6-diamidino-2-phenylindole (DAPI) nuclear counterstain. Next, RPE cells were uniquely identified in the green channel using an anti-retinal pigment epithelium-specific protein 65 kDa (anti-RPE65) monoclonal antibody with an Alexa Fluor 488-labeled secondary antibody. Mn-superoxide dismutase (MnSOD) was quantified in the long-red channel using an anti-MnSOD antibody and an Alexa Fluor 647-labeled secondary antibody. MnSOD(+) and RPE65(+) cells exhibited peaks in the plot of fluorescence intensity versus cell number, which could be characterized by the mean fluorescence intensity (MFI), the coefficient of variation (CV), and the percentage of total RPE cells that were also labeled for MnSOD.

RESULTS

RPE cells can be uniquely identified in human and mouse paraffin sections by immunolabeling with anti-RPE65 antibody. A second antigen, such as MnSOD, can then be probed only within this set of RPE. Results are plotted primarily with the population frequency diagram, which can be subdivided into multiple regions. The data collected for each region include the MFI, the CV, and the number of cells that are immunolabeled in that region. Background interference from pigment or autofluorescent material can be successfully overcome by elevating the concentrations of fluorescent secondary antibodies. In the human and mouse eyes, age-related changes in MFI, CV, and percent RPE cells immunolabeled for MnSOD were observed.

CONCLUSIONS

The extent of the variability of gene expression in RPE cells at the protein level can be quantified by LSC. Relative changes in the MFI, the CV, and/or percentage of RPE cells double labeled for a second antigen quantify the changes observed. The analysis of these data also suggest whether the effects observed are related to local changes in transcription (alterations of CV) or major changes of protein expression (MFI), which are likely to be due to changes in the chromatin structure. The changes of these variables with age suggest that the observed age-related variegation is primarily due to changes in the chromatin structure in individual cells.

CFH, C3 and ARMS2 are significant risk loci for susceptibility but not for disease progression of geographic atrophy due to AMD

Background

Age-related macular degeneration (AMD) is a prevalent cause of blindness in Western societies. Variants in the genes encoding complement factor H (CFH), complement component 3 (C3) and age-related maculopathy susceptibility 2 (ARMS2) have repeatedly been shown to confer significant risks for AMD; however, their role in disease progression and thus their potential relevance for interventional therapeutic approaches remains unknown.

Methodology/Principal Findings

Here, we analyzed association between variants in CFH, C3 and ARMS2 and disease progression of geographic atrophy (GA) due to AMD. A quantitative phenotype of disease progression was computed based on longitudinal observations by fundus autofluorescence imaging. In a subset of 99 cases with pure bilateral GA, variants in CFH (Y402H), C3 (R102G), and ARMS2 (A69S) are associated with disease (P = 1.6×10⁻⁹, 3.2×10⁻³, and P = 2.6×10⁻¹², respectively) when compared to 612 unrelated healthy control individuals. In cases, median progression rate of GA over a mean follow-up period of 3.0 years was 1.61 mm²/year with high concordance between fellow eyes. No association between the progression rate and any of the genetic risk variants at the three loci was observed (P>0.13).

Conclusions/Significance

This study confirms that variants at CFH, C3, and ARMS2 confer significant risks for GA due to AMD. In contrast, our data indicate no association of these variants with disease progression which may have important implications for future treatment strategies. Other, as yet unknown susceptibilities may influence disease progression.

Correlation between spectral-domain optical coherence tomography and fundus autofluorescence at the margins of geographic atrophy

PURPOSE

To study the appearance of margins of geographic atrophy in high-resolution optical coherence tomography (OCT) images and to correlate those changes with fundus autofluorescence (FAF) imaging.

DESIGN

Retrospective, observational case study.

METHODS

Patients with geographic atrophy secondary to dry age-related macular degeneration were assessed by means of spectral-domain OCT (Spectralis Heidelberg Retinal Angiograph/OCT; Heidelberg Engineering, Heidelberg, Germany; or OTI Inc, Toronto, Canada) as well as autofluorescence imaging (Heidelberg Retinal Angiograph or Spectralis; Heidelberg Engineering). The outer retinal layer alterations were analyzed in the junctional zone between normal retina and atrophic retina and were correlated with corresponding FAF.

RESULTS

Twenty-three eyes of 16 patients between 62 and 96 years of age were examined. There was a significant association between OCT findings and the FAF findings (r = 0.67; P < .0001). Severe alterations of the outer retinal layers at margins on spectral-domain OCT correspond significantly to increased autofluorescence; smooth margins on OCT correspond significantly to normal FAF (kappa, 0.7348; P < .0001).

CONCLUSIONS

Spectral-domain OCT provides in vivo insight into the pathogenesis of geographic atrophy and its progression. Visualization of reactive changes in the retinal pigment epithelial cells at the junctional zone and correlation with increased FAF; secondary to increased lipofuscin, together these methods may serve as determinants of progression of geographic atrophy.

Fundus autofluorescence and progression of age-related macular degeneration

Fundus autofluorescence imaging is an imaging method that provides additional information compared to conventional imaging techniques. It permits to topographically map lipofuscin distribution of the retinal pigment epithelial cell monolayer. Excessive accumulation of lipofuscin granules in the lysosomal compartment of retinal pigment epithelium cells represents a common downstream pathogenetic pathway in various hereditary and complex retinal diseases including age-related macular degeneration (AMD). This comprehensive review contains an introduction in fundus autofluorescence imaging, including basic considerations, the origin of the signal, different imaging methods, and a brief overview of fundus autofluorescence findings in normal subjects. Furthermore, it summarizes cross-sectional and longitudinal fundus autofluorescence findings in patients with AMD, addresses the pathophysiological significance of increased fundus autofluorescence, and characterizes different fundus autofluorescence phenotypes as well as fundus autofluorescence alterations with disease progression.

Lipofuscin- and melanin-related fundus autofluorescence visualize different retinal pigment epithelial alterations in patients with retinitis pigmentosa

AIMS

To compare melanin-related near-infrared fundus autofluorescence (FAF; NIA, excitation 787 nm, emission >800 nm) with lipofuscin-related FAF (excitation 488 nm, emission >500 nm) in retinitis pigmentosa (RP).

METHODS

Thirty-three consecutive RP patients with different modes of inheritance were diagnosed clinically, with full-field ERG, and if possible with molecular genetic methods. FAF and NIA imaging were performed with a confocal scanning laser ophthalmoscope (Heidelberg Retina Angiograph 2).

RESULTS

Rings of increased FAF were present within an area of preserved retinal pigment epithelium (RPE) at the posterior pole (31/33). Rings of increased NIA were located in the same region as rings of increased FAF. In contrast to FAF, NIA showed a precipitous decline of NIA peripheral to the ring. In larger areas of preserved NIA (11/31), pericentral and foveal NIA were of similar intensity with an area of lower NIA in between. In smaller areas of preserved NIA (20/31), NIA was homogeneous from the perifovea to the fovea. In one patient without a ring of increased FAF, NIA distribution was normal. In the remaining patient with severely advanced RP, no residual RPE as well as no FAF and NIA were detectable.

CONCLUSION

Characteristic features for FAF and NIA alterations in a heterogeneous group of RP patients indicate a common pathway of RPE degeneration. Patterns of NIA and FAF indicate different pathophysiologic processes involving melanin and lipofuscin. Combined NIA and FAF imaging will provide further insight into the pathogenesis of RP and non-invasive monitoring of future therapeutic interventions.

Evaluation of autofluorescence imaging with the scanning laser ophthalmoscope and the fundus camera in age-related geographic atrophy

PURPOSE

To compare fundus autofluorescence images (FAF) between a modified fundus camera (mFC) and a confocal scanning laser ophthalmoscope (cSLO).

DESIGN

Evaluation of diagnostic technology.

METHODS

Thirty-two eyes of 16 patients with age-related geographic atrophy (GA) treated in an institutional setting were included. FAF images were obtained with both the cSLO (excitation, 488 nm; emission, > 500 nm) and the mFC (excitation, approximately 500 to 610 nm; emission, approximately 675 to 715 nm). Using established algorithms, images were graded by two independent observers and agreements were evaluated. The main outcome measures were image quality, quantification of total atrophy, and classification of FAF patterns.

RESULTS

In two eyes with advanced cataract (lens grade 7 according to the Age-Related Eye Disease Study classification), FAF image quality with both systems was not sufficient for any meaningful analysis. In the remaining 30 eyes, the mean differences of the interobserver agreements for atrophy quantification were 0.16 mm2 (95% confidence interval [CI], 0.07 to 0.38) for mFC and 0.15 mm2 (95% CI, -0.04 to 0.33) for cSLO images. Because of inferior signal-to-noise ratios, FAF pattern classification was possible in a lower number of mFC images (69%) compared with cSLO images (88%).

CONCLUSIONS

This study suggests that the agreements for atrophy quantification are similar with both devices. The lesser visualization of FAF patterns with the mFC and thus inferior determination of disease markers may be the result of the nonconfocality and the use of single instead of mean images compared with the cSLO. These findings may be important for the design of interventional trials as well as the routine use of FAF imaging in age-related geographic atrophy.

Progression of geographic atrophy and impact of fundus autofluorescence patterns in age-related macular degeneration

PURPOSE

To test if fundus autofluorescence (FAF) patterns around geographic atrophy (GA) have an impact on GA progression rates over time in atrophic age-related macular degeneration (AMD).

DESIGN

Prospective longitudinal multicenter natural history study.

METHODS

Standardized digital FAF images were obtained from 195 eyes of 129 patients with GA using confocal scanning laser ophthalmoscopy (excitation 488 nm, emission >500 nm). Areas of GA were quantified and patterns of abnormal FAF in the junctional zone were classified. Repeated FAF images were obtained over a median follow-up period of 1.80 years (interquartile range [IQR], 1.28 to 3.34).

RESULTS

Areas of GA (median, 7.04 mm(2) at baseline; IQR, 3.12 to 10.0) showed a median enlargement of 1.52 mm(2)/year (IQR, 0.81 to 2.33). Progression rates in eyes with the banded (median 1.81 mm(2)/year) and the diffuse FAF pattern (1.77 mm(2)/year) were significantly higher compared to eyes without FAF abnormalities (0.38 mm(2)/year) and focal FAF patterns (0.81 mm(2)/year, P < .0001). Within the group of the diffuse pattern, eyes with a diffuse trickling pattern could be identified that exhibited an even higher spread rate (median 3.02 mm(2)/year) compared to the other diffuse types (1.67 mm(2)/year, P = .001).

CONCLUSIONS

The results indicate that distinct phenotypic FAF patterns have an impact on disease progression in eyes with atrophic AMD and may therefore serve as prognostic determinants. The findings underscore the relevance of FAF imaging and the pathogenetic role of excessive retinal pigment epithelium (RPE) lipofuscin (LF) accumulation in GA. Natural history data and identification of high-risk characteristics will be helpful to design interventional studies aiming at slowing the spread of atrophy.

An update on the genetics of age-related macular degeneration

Age-related macular degeneration (AMD) is a genetically complex disorder of the photoreceptor-RPE-Bruch's membrane-choriocapillaris complex. Family and twin studies have shown that the susceptibility for this disease is genetically influenced. The heritability has been estimated to be up to 71%. Linkage and association studies have identified several chromosomal regions that are likely to contain susceptibility loci with strongest evidence found on chromosome 1q31 and 10q26. Variants in the complement factor H (CFH) gene have been shown by several independent studies to be associated with an increased risk for AMD in Caucasian populations. These findings imply that the innate immune system may play a significant role in AMD pathogenesis. The LOC387715/HTRA1 locus within 10q26 has been identified as a second major locus contributing to AMD pathogenesis. The two late forms of AMD, choroidal neovascularization and geographic atrophy, have not been found to be different in risk allele distribution. Variants within CFH and LOC387715/HTRA1 may contribute to the increased risk of late AMD largely through their impact on precursors, such as drusen and/or other RPE/Bruch's membrane changes. Considering variants at CFH, LOC387715/HTRA1 and complement component 2-complement factor B (C2-FB), high-risk homozygotes at all three loci may have a 250-fold increased risk compared to baseline. However, the identification of genetic factors has not resulted in therapeutic strategies to modify the disease so far and additional genetic and environmental factors are yet to be discovered in order to influence the onset and the progression of AMD.

Autofluorescence characteristics of early, atrophic, and high-risk fellow eyes in age-related macular degeneration

PURPOSE

To assess the relationships of drusen, pigment, and focally increased autofluorescence (FIAF) and the reticular pattern of hypoautofluorescence, to distinguish the combined photographic and AF characteristics of early, atrophic, and high-risk fellow eyes in AMD.

METHODS

In a retrospective interinstitutional clinical study, AF and color photograph pairs of 221 eyes were examined: 166 eyes of 83 patients with bilateral large, soft drusen, with and without geographic atrophy (GA), and 55 fellow eyes of 55 patients with unilateral choroidal neovascularization (CNV). Forty-two eyes (one eye from each of 42 patients with early or atrophic AMD) were divided into four groups: 14 with drusen only, 9 with drusen and pigment abnormalities, 11 fellow eyes of patients with unilateral GA, and 8 eyes of patients with bilateral GA (acronyms for the groups: D-D, D-Pig, D-GA and GA-GA, respectively). The 55 fellow eyes of patients with CNV were divided into three groups: 19 eyes with no FIAF (CNV-0), 16 with FIAF without reticular AF (CNV-1), and 20 eyes with reticular AF and/or pseudodrusen (CNV-R). Image pairs of eyes with FIAF were registered, and drusen, pigment, and FIAF were segmented using automated background leveling and thresholding. All 221 eyes were surveyed for reticular AF and reticular pseudodrusen. The main outcome measures were (1) the fraction and relative probability of FIAF colocalizing with drusen and pigment and (2) the presence or absence of reticular AF and reticular pseudodrusen.

RESULTS

The mean fractions of FIAF that colocalized with large drusen were: D-D group, 0.46 +/- 0.21; D-Pig group, 0.42 +/- 0.29; D-GA group, 0.13 +/- 0.09; and GA-GA group, 0.11 +/- 0.12. Comparisons between groups showed significant differences when comparing either the D-D group or the D-Pig group with either the D-GA group or the GA-GA group (P between 0.0001 and 0.015), whereas other comparisons were nonsignificant (Mann-Whitney rank sum test). The mean probabilities of FIAF colocalizing with large drusen relative to chance (1.0) were: D-D group, 4.7 +/- 2.5; D-Pig group, 4.3 +/- 2.3; D-GA group, 1.4 +/- 0.8; and GA-GA group, 1.8 +/- 1.3, with similar significant differences as for the colocalization fractions. The mean probability of FIAF colocalizing with small to intermediate drusen in the D-D group was 1.5 +/- 1.3, which was not significantly different from chance. In the D-Pig group, the median probability of FIAF colocalizing with pigment abnormalities was 10.0 (range, 1.1-51.0). The AF patterns in 15 of 19 eyes in the CNV-0 group were normal; the remainder had nonreticular hypoautofluorescence only. In the CNV-1 group, the relations of FIAF with drusen and pigment were similar to those in the early AMD groups. CNV-R comprised 20 of 55 eyes in the CNV group, but reticular autofluorescence and/or pseudodrusen were found in only 14 of 166 eyes of the early and atrophic groups. Of the 34 total eyes with reticular AF or pseudodrusen, 28 had both, 4 had reticular AF only, and 2 had reticular pseudodrusen only.

CONCLUSIONS

There are clear relationships between AF patterns and clinical AMD status. In early AMD, FIAF's colocalization with large, soft drusen and hyperpigmentation is several times greater than chance, suggesting linked disease processes. In advanced atrophic AMD, FIAF is found mostly adjacent to drusen and GA, suggesting that dispersal of drusen-associated lipofuscin is a marker of atrophic disease progression. In the neovascular case, a large group of fellow eyes have no FIAF abnormalities, suggesting that lipofuscin is not a major determinant of CNV. However, reticular hypoautofluorescence, consistent with widespread inflammatory damage to the RPE, appears to be a highly sensitive imaging marker for the disease that determines reticular pseudodrusen and is strongly associated with CNV.

Development of atrophy of the retinal pigment epithelium around disciform scars

BACKGROUND/AIMS

Eyes with burnt out disciform scars secondary to age related macular degeneration (AMD) are regarded as visually stable. The aim of this study is to report the subsequent development of atrophy of the retinal pigment epithelium (RPE) around the scars and discuss the possible basis.

METHODS

20 eyes from 18 patients were observed to develop atrophy around choroidal neovascularisation (CNV). A method of measuring expansion of the atrophy over time is described using the Topcon Imagenet 2000 system. An additional 10 clinicopathological examples were reviewed.

RESULTS

Clinically CNV became surrounded initially by a ring of pallor that progressed to an expanding band of atrophy of the RPE. It developed most rapidly in the first 3 years after CNV became quiescent but then continued to expand slowly to more than three times the size of the scar. Histopathological specimens showed large choroidal vessels entering the scars directly and a reduced number of small choroidal vessels beneath and around the scar

CONCLUSIONS

Disciform scars may become surrounded by an expanding band of atrophy of the RPE, postulated to result from remodelling of the choroidal circulation. The ongoing enlargement of the resulting scotoma may need to be considered when planning management and assessing treatment outcomes.

Age-related maculopathy and the impact of blue light hazard

The pathogenesis of age-related maculopathy (ARM), the most common cause of visual loss after the age of 60 years, is indeed a complicated scenario that involves a variety of hereditary and environmental factors. The pathological cellular and molecular events underlying retinal photochemical light damage, including photoreceptor apoptosis, have been analysed in experimental animal models. Studies of age-related alterations of the retina and photoreceptors, the accumulation of lipofuscin in retinal pigment epithelium (RPE) cells, and the formation of drusen have greatly contributed to our knowledge. A new concept of an inflammatory response to drusen has emerged, suggesting immunogenic and systemic reactions in Bruch's membrane and the subretinal space. Oxidative stress and free radical damage also impact on the photoreceptors and RPE cells in the ageing eye. Based on the photoelectric effect, a fundamental concept in quantum physics, the consequences of high-energy irradiation have been analysed in animal models and cell culture. Short-wavelength radiation (rhodopsin spectrum), and the blue light hazard (excitation peak 440 nm), have been shown to have a major impact on photoreceptor and RPE function, inducing photochemical damage and apoptotic cell death. Following cataract surgery, there is a dramatic change in ocular transmittance. In aphakic or pseudophakic eyes (with clear intraocular lenses), high-energy (blue) and ultraviolet-A radiation strikes the retina. Epidemiological data indicate a significantly increased 5-year incidence of late ARM in non-phakic eyes compared with phakic eyes. In recent years, putative prophylactic measures against ARM have emerged. The implantation of 'yellow' intraocular lenses (IOLs) that absorb high-energy blue radiation is, from a theoretical point of view, the most rational approach, and, from a practical point of view, is easy to accomplish. With increasing age, RPE cells accumulate lipofuscin (chromophore A2E). It is noteworthy that the yellow IOL not only protects A2E-laden human RPE cells from blue light (peak 430 nm) damage, but also alleviates the detrimental effects of green (peak 550 nm) and white light. A prophylactic treatment using antioxidants is aimed at counteracting oxidative stress and free radical cellular damage. The Age-Related Eye Disease Study (AREDS), a randomized clinical trial, showed a significantly lower incidence of late ARM in a cohort of patients with drusen maculopathy treated with high doses of antioxidants than in a placebo group. In recent years, considerable progress in retinal research has been achieved, creating a platform for the search for new prophylactic and therapeutic measures to alleviate or prevent photoreceptor and RPE degeneration in ARM.