Prospective evaluation of digital non-stereo color fundus photography as a screening tool in age-related macular degeneration

Empowering Portable Age-Related Macular Degeneration Screening: Evaluation of a Deep Learning Algorithm for a Smartphone Fundus Camera

OBJECTIVES

Despite global research on early detection of age-related macular degeneration (AMD), not enough is being done for large-scale screening. Automated analysis of retinal images captured via smartphone presents a potential solution; however, to our knowledge, such an artificial intelligence (AI) system has not been evaluated. The study aimed to assess the performance of an AI algorithm in detecting referable AMD on images captured on a portable fundus camera.

DESIGN, SETTING

A retrospective image database from the Age-Related Eye Disease Study (AREDS) and target device was used.

PARTICIPANTS

The algorithm was trained on two distinct data sets with macula-centric images: initially on 108,251 images (55% referable AMD) from AREDS and then fine-tuned on 1108 images (33% referable AMD) captured on Asian eyes using the target device. The model was designed to indicate the presence of referable AMD (intermediate and advanced AMD). Following the first training step, the test set consisted of 909 images (49% referable AMD). For the fine-tuning step, the test set consisted of 238 (34% referable AMD) images. The reference standard for the AREDS data set was fundus image grading by the central reading centre, and for the target device, it was consensus image grading by specialists.

OUTCOME MEASURES

Area under receiver operating curve (AUC), sensitivity and specificity of algorithm.

RESULTS

Before fine-tuning, the deep learning (DL) algorithm exhibited a test set (from AREDS) sensitivity of 93.48% (95% CI: 90.8% to 95.6%), specificity of 82.33% (95% CI: 78.6% to 85.7%) and AUC of 0.965 (95% CI:0.95 to 0.98). After fine-tuning, the DL algorithm displayed a test set (from the target device) sensitivity of 91.25% (95% CI: 82.8% to 96.4%), specificity of 84.18% (95% CI: 77.5% to 89.5%) and AUC 0.947 (95% CI: 0.911 to 0.982).

CONCLUSION

The DL algorithm shows promising results in detecting referable AMD from a portable smartphone-based imaging system. This approach can potentially bring effective and affordable AMD screening to underserved areas.

Diagnostic accuracy of community optometrists for age-related macular degeneration using colour fundus photographs: A pilot evaluation

PURPOSE

The accurate diagnosis of age-related macular degeneration (AMD) represents an important step in delaying and preventing vision loss and achieving optimal patient care. Therefore, this pilot study aimed to estimate the diagnostic accuracy of community optometrists for identifying AMD using colour fundus photographs (CFPs) to support sample size calculations for subsequent definitive studies.

METHODS

Five practising community optometrists were invited to classify a total of 1023 CFPs for the (1) presence of AMD, and, if applicable, (2) stage of AMD (early/intermediate/late geographic atrophy/late neovascular AMD). Diagnosis by referral centre clinicians formed the reference standard. Diagnostic accuracy was assessed by the area under the receiver operating characteristic curve (aROC). Sensitivity, specificity, positive and negative predictive values were also calculated.

RESULTS

Of the 1023 CFPs included in the study, 226 images were of AMD and 797 images were of other ocular conditions or no abnormal findings. Participating community optometrists had a mean (SD) age of 30.2 (8.9) years, 60.0% (3/5) were female and the mean number of years practising in primary eye care was 5.4 (5.4) years. Community optometrists demonstrated excellent performance for diagnosing AMD, with an aROC of 0.86 (95% CI 0.83 to 0.89), sensitivity of 84.5% (95% CI 79.1 to 89.0) and specificity of 88.0% (95% CI 85.5 to 90.1). The aROC (95% CI) for diagnosing early, intermediate, late geographic atrophy and late neovascular AMD was 0.82 (0.73 to 0.91), 0.76 (0.72 to 0.81), 0.69 (0.49 to 0.90) and 0.55 (0.34 to 0.75), respectively.

CONCLUSIONS

These results justify the need for an appropriately powered definitive study to assess community clinicians' diagnostic accuracy for AMD.

Telemedicine for the Diagnosis and Management of Age-Related Macular Degeneration: A Review

Use of ophthalmic telemedicine for patients with age-related macular degeneration (AMD) has shown remarkable advances over recent years. The recent COVID pandemic accelerated this transition since in-person evaluation of elderly patients at high risk for advanced AMD and severe vision loss were also at higher risk for complications from COVID infection. To date, ophthalmic telemedicine has been successfully used in remote retinal consultation by general ophthalmologists for AMD management, hybrid testing visits with both in-office testing and remote evaluation, as well as early successes in home-based remote monitoring of patients with high-risk AMD. We therefore review the current literature and evidence base related to ophthalmic telemedicine for AMD.

COVID-19 Launches Retinal Telemedicine into the Next Frontier

INTRODUCTION

Telemedicine in ophthalmology, and specifically in retinal diseases, has made significant advancements in recent years. The COVID-19 pandemic has launched telehealth into a new era by creating demand from patients and physicians alike, while breaking down previous insurance, reimbursement, access and educational barriers.

METHODS

This paper reviews mulitple studies demonstrating the use of telemedicine in managing various retinal conditions before and during the COVID-19 pandemic.

CONCLUSION

Moving forward, promising new devices and models of care ensure that tele-retinal care will continue to expand and become a vital part of how we screen, diagnose and monitor retinal diseases.

Health screening program revealed risk factors associated with development and progression of papillomacular bundle defect

BACKGROUND/AIMS

The papillomacular bundle (PMB) area is an important anatomical site associated with central vision. As preventive medicine and health screening examinations are now becoming commonplace, the incidental detection of papillomacular bundle defect (PMBD) on fundus photography has been increasing. However, clinical significance of incidental PMBD has not been well documented to date. Thus, through long-term and longitudinal observation, we aimed to investigate the risk factors for the development and progression of PMBD and its predictive role associated with systemic diseases and glaucoma.

METHODS

This longitudinal study included subjects who had undergone standardized health screening. We retrospectively reviewed patients for whom PMBD had been detected in fundus photography and followed up for more than 5 years. For a comparative analysis, non-PMBD groups of age- and gender-matched healthy controls were selected.

RESULTS

A total of about 67,000 fundus photographs were analyzed for 8.0 years, and 587 PMBD eyes were found. Among them, 234 eyes of 234 patients who had had fundus photographs taken for more than 5 years were finally included. A total of 216 eyes (92.3%) did not progress during the 8.1 ± 2.7 years, whereas 18 eyes (7.7%) showed progression at 7.6 ± 2.9 years after initial detection. A multivariate logistic regression analysis using 224 non-PMBD healthy controls revealed low body mass index (BMI < 20 kg/m2), systemic hypertension, and sclerotic changes of retinal artery as the significant risk factors for the development of PMBD. Regarding PMBD progression, low BMI, concomitant retinal nerve fiber layer defect (RNFLD) at non-PMB sites, optic disc hemorrhage, and higher vertical cup/disc ratio were individual significant risk factors.

CONCLUSION

PMBD is associated with ischemic effects. Although the majority of PMBD do not progress, some of cases are associated with glaucomatous damage in a long-term way. PMBD might be a personalized indicator representing ischemia-associated diseases and a predictive factor for diagnosis and preventive management of glaucoma.

Association between cardiorespiratory fitness and handgrip strength with age-related macular degeneration: a population-based study

AIM

To assess whether cardiorespiratory fitness (CRF) and handgrip strength, two objective markers of physical fitness, are associated with age-related macular degeneration (AMD).

METHODS

We analysed cross-sectional data from the population-based Study of Health in Pomerania (2008-2012) including 1173 adult men and women aged 20-79 years. Fundus photography of the central retina was recorded with a non-mydriatic camera, and images were graded according to an established clinical AMD classification scale by an experienced reader. CRF was measured using peak oxygen uptake (peakVO₂), oxygen uptake at the anaerobic threshold (VO₂@AT), and maximum power output (W_max) from standardised cardiopulmonary exercise testing on a bicycle ergometer according to a modified Jones protocol. Handgrip strength was assessed using a handheld dynamometer. Adjusted prevalence ratios (PR) for the associations of peakVO₂, VO₂@AT, W_max and handgrip strength with AMD were derived from multivariable Poisson regression models.

RESULTS

PeakVO₂, VO₂@AT, W_max and handgrip strength were not associated with AMD. Adjusted PR for AMD associated with a 1-SD increment in peakVO₂, VO₂@AT, W_max and handgrip strength were 1.05 (95% CI 0.82 to 1.34), 0.96 (95% CI 0.78 to 1.18), 1.10 (95% CI 0.86 to 1.41) and 1.01 (95% CI 0.79 to 1.30), respectively. These associations were not modified by age, sex, smoking, body mass index and diabetes. Estimates in sensitivity analysis for confounding, selection bias and missing data were similar.

CONCLUSION

In our study, CRF and handgrip strength were not associated with AMD. Nevertheless, longitudinal studies with bigger sample sizes are needed to furtherly examine these associations.

Comparison of Drusen Volume Assessed by Two Different OCT Devices

To compare drusen volume between Heidelberg Spectral Domain (SD-) and Zeiss Swept-Source (SS) PlexElite Optical Coherence Tomography (OCT) determined by manual and automated segmentation methods. Thirty-two eyes of 24 patients with Age-Related Macular Degeneration (AMD) and drusen maculopathy were included. In the central 1 and 3 mm ETDRS circle drusen volumes were calculated and compared. Drusen segmentation was performed using automated manufacturer algorithms of the two OCT devices. Then, the automated segmentation was manually corrected and compared and finally analyzed using customized software. Though on SD-OCT, there was a significant difference of mean drusen volume prior to and after manual correction (mean difference: 0.0188 ± 0.0269 mm³, p < 0.001, corr. p < 0.001, correlation of r = 0.90), there was no difference found on SS-OCT (mean difference: 0.0001 ± 0.0003 mm³, p = 0.262, corr. p = 0.524, r = 1.0). Heidelberg-acquired mean drusen volume after manual correction was significantly different from Zeiss-acquired drusen volume after manual correction (mean difference: 0.1231 ± 0.0371 mm³, p < 0.001, corr. p < 0.001, r = 0.68). Using customized software, the difference of measurements between both devices decreased and correlation among the measurements improved (mean difference: 0.0547 ± 0.0744 mm³, p = 0.02, corr. p = 0.08, r = 0.937). Heidelberg SD-OCT, the Zeiss PlexElite SS-OCT, and customized software all measured significantly different drusen volumes. Therefore, devices/algorithms may not be interchangeable. Third-party customized software helps to minimize differences, which may allow a pooling of data of different devices, e.g., in multicenter trials.

Optical coherence tomography and color fundus photography in the screening of age-related macular degeneration: A comparative, population-based study

Purpose

To analyze the individual value and the contribution of color fundus photography (CFP) and optical coherence tomography (OCT) in the screening of age-related macular degeneration (AMD) of an unselected population.

Methods

CFP and OCT images of 15957 eyes of 8069 subjects older than 55 years, obtained during a population-based screening for AMD using a single diagnostic non-mydriatic imaging device, were analyzed by a blinded examiner. The two techniques were preliminary evaluated considering the dichotomous parameter "gradable/ungradable", then gradable images were classified. CFP were graded according to the standardized classification of AMD lesions. OCT images were also categorized considering the presence of signs of early/intermediate AMD, late AMD, or other retinal diseases. Another blinded operator re-graded 1978 randomly selected images (for both CFP and OCT), to assess test reproducibility.

Results

Of the 15957 eyes, 8356 CFP (52.4%) and 15594 (97.7%) OCT scans were gradable. Moreover, most of the eyes with ungradable CFP (7339, 96.6%) were gradable at OCT. AMD signs were revealed in 7.4% of gradable CFP and in 10.4% of gradable OCT images. Moreover, at OCT, AMD signs were found in 1110 (6.9%) eyes whose CFP were ungradable or without AMD (847 and 263 eyes, respectively). The inter-operator agreement was good for the gradable versus ungradable parameter, and optimal for the AMD grading parameter of CFP. The agreement was optimal for all OCT parameters.

Conclusions

OCT provided gradable images in almost all examined eyes, compared to limited CFP efficiency. Moreover, OCT images allowed to detect more AMD eyes compared to gradable photos. OCT imaging appears to significantly improve the power of AMD screening in a general, unselected population, compared to CFP alone.

Cost-effectiveness and diagnostic accuracy of telemedicine in macular disease and diabetic retinopathy: A systematic review and meta-analysis

OBJECTIVE

To determine cost-effectiveness and the diagnostic accuracy of teleophthalmology (TO) in the detection of macular edema (ME) and various grades of diabetic retinopathy (DR).

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched for TO, ME, and DR on May 25, 2016. The search was updated on April 2, 2019. Pooled sensitivity and specificity for ME and various grades of DR were determined using Meta-Disc software. A systematic review of the articles discussing the cost-effectiveness of TO screening was also performed.

RESULTS

Thirty-three articles on the diagnostic accuracy and 28 articles on the cost-effectiveness were selected.

CONCLUSIONS

Telescreening is moderately sensitive but very specific for the diagnosis of diabetic retinopathy. Non-mydriatic Teleretinal screening services are cost-effective, decrease clinics workload, and increase patient compliance if provided free of cost in remote low socioeconomic regions.

Practice Guidelines for Ocular Telehealth-Diabetic Retinopathy, Third Edition

Contributors The following document and appendices represent the third edition of the Practice Guidelines for Ocular Telehealth-Diabetic Retinopathy. These guidelines were developed by the Diabetic Retinopathy Telehealth Practice Guidelines Working Group. This working group consisted of a large number of subject matter experts in clinical applications for telehealth in ophthalmology. The editorial committee consisted of Mark B. Horton, OD, MD, who served as working group chair and Christopher J. Brady, MD, MHS, and Jerry Cavallerano, OD, PhD, who served as cochairs. The writing committees were separated into seven different categories. They are as follows: 1.Clinical/operational: Jerry Cavallerano, OD, PhD (Chair), Gail Barker, PhD, MBA, Christopher J. Brady, MD, MHS, Yao Liu, MD, MS, Siddarth Rathi, MD, MBA, Veeral Sheth, MD, MBA, Paolo Silva, MD, and Ingrid Zimmer-Galler, MD. 2.Equipment: Veeral Sheth, MD (Chair), Mark B. Horton, OD, MD, Siddarth Rathi, MD, MBA, Paolo Silva, MD, and Kristen Stebbins, MSPH. 3.Quality assurance: Mark B. Horton, OD, MD (Chair), Seema Garg, MD, PhD, Yao Liu, MD, MS, and Ingrid Zimmer-Galler, MD. 4.Glaucoma: Yao Liu, MD, MS (Chair) and Siddarth Rathi, MD, MBA. 5.Retinopathy of prematurity: Christopher J. Brady, MD, MHS (Chair) and Ingrid Zimmer-Galler, MD. 6.Age-related macular degeneration: Christopher J. Brady, MD, MHS (Chair) and Ingrid Zimmer-Galler, MD. 7.Autonomous and computer assisted detection, classification and diagnosis of diabetic retinopathy: Michael Abramoff, MD, PhD (Chair), Michael F. Chiang, MD, and Paolo Silva, MD.

Telemedicine for Age-Related Macular Degeneration

Background: As the leading cause of vision loss in the United States, age-related macular degeneration (AMD) would seem to be amenable to interventions that increase access to screening and management services for patients. AMD poses several unique challenges for telemedicine, however. The disease lacks clinical consensus on the effectiveness and cost-effectiveness of screening the general population, and more complex imaging modalities may be required than for what has traditionally been used for diabetic retinopathy telehealth systems. Methods: The current literature was reviewed to find clinical trials and expert consensus documents on the state-of-the-art of telemedicine for AMD. Results: A range of feasibility studies have reported success with telemedicine strategies for AMD. Several investigators have reported experience with AMD screening and remote-monitoring systems as well as artificial intelligence applications. Conclusions: There are currently no large-scale telemedicine programs for either screening or managing AMD, but new approaches to screening and managing the condition may allow for expansion of high-quality convenient care for an increasing patient population.

Effects of Hypertension, Diabetes, and Smoking on Age and Sex Prediction from Retinal Fundus Images

Retinal fundus images are used to detect organ damage from vascular diseases (e.g. diabetes mellitus and hypertension) and screen ocular diseases. We aimed to assess convolutional neural network (CNN) models that predict age and sex from retinal fundus images in normal participants and in participants with underlying systemic vascular-altered status. In addition, we also tried to investigate clues regarding differences between normal ageing and vascular pathologic changes using the CNN models. In this study, we developed CNN age and sex prediction models using 219,302 fundus images from normal participants without hypertension, diabetes mellitus (DM), and any smoking history. The trained models were assessed in four test-sets with 24,366 images from normal participants, 40,659 images from hypertension participants, 14,189 images from DM participants, and 113,510 images from smokers. The CNN model accurately predicted age in normal participants; the correlation between predicted age and chronologic age was R² = 0.92, and the mean absolute error (MAE) was 3.06 years. MAEs in test-sets with hypertension (3.46 years), DM (3.55 years), and smoking (2.65 years) were similar to that of normal participants; however, R² values were relatively low (hypertension, R² = 0.74; DM, R² = 0.75; smoking, R² = 0.86). In subgroups with participants over 60 years, the MAEs increased to above 4.0 years and the accuracies declined for all test-sets. Fundus-predicted sex demonstrated acceptable accuracy (area under curve > 0.96) in all test-sets. Retinal fundus images from participants with underlying vascular-altered conditions (hypertension, DM, or smoking) indicated similar MAEs and low coefficients of determination (R²) between the predicted age and chronologic age, thus suggesting that the ageing process and pathologic vascular changes exhibit different features. Our models demonstrate the most improved performance yet and provided clues to the relationship and difference between ageing and pathologic changes from underlying systemic vascular conditions. In the process of fundus change, systemic vascular diseases are thought to have a different effect from ageing. Research in context. Evidence before this study. The human retina and optic disc continuously change with ageing, and they share physiologic or pathologic characteristics with brain and systemic vascular status. As retinal fundus images provide high-resolution in-vivo images of retinal vessels and parenchyma without any invasive procedure, it has been used to screen ocular diseases and has attracted significant attention as a predictive biomarker for cerebral and systemic vascular diseases. Recently, deep neural networks have revolutionised the field of medical image analysis including retinal fundus images and shown reliable results in predicting age, sex, and presence of cardiovascular diseases. Added value of this study. This is the first study demonstrating how a convolutional neural network (CNN) trained using retinal fundus images from normal participants measures the age of participants with underlying vascular conditions such as hypertension, diabetes mellitus (DM), or history of smoking using a large database, SBRIA, which contains 412,026 retinal fundus images from 155,449 participants. Our results indicated that the model accurately predicted age in normal participants, while correlations (coefficient of determination, R²) in test-sets with hypertension, DM, and smoking were relatively low. Additionally, a subgroup analysis indicated that mean absolute errors (MAEs) increased and accuracies declined significantly in subgroups with participants over 60 years of age in both normal participants and participants with vascular-altered conditions. These results suggest that pathologic retinal vascular changes occurring in systemic vascular diseases are different form the changes in spontaneous ageing process, and the ageing process observed in retinal fundus images may saturate at age about 60 years. Implications of all available evidence. Based on this study and previous reports, the CNN could accurately and reliably predict age and sex using retinal fundus images. The fact that retinal changes caused by ageing and systemic vascular diseases occur differently motivates one to understand the retina deeper. Deep learning-based fundus image reading may be a more useful and beneficial tool for screening and diagnosing systemic and ocular diseases after further development.

Can Artificial Intelligence Make Screening Faster, More Accurate, and More Accessible?

Diabetic retinopathy, glaucoma, and age-related macular degeneration are leading causes of vision loss and blindness worldwide. They tend to be asymptomatic in the early phase of disease and therefore require active screening programs to identify the patients requiring referral and treatment. Deep learning-based artificial intelligence technology has recently become a major topic in the field of ophthalmology. This paper aimed to provide a general view of the major findings on the application of deep learning for the classification of eye diseases from common imaging modalities. In the future, it is expected that these technologies will be applied in real-world screening programs to improve their efficiency and affordability.

Smartphones, tele-ophthalmology, and VISION 2020

Telemedicine is an emerging field in recent medical achievements with rapid development. The "smartphone" availability has increased in both developed and developing countries even among people in rural and remotes areas. Tele-based services can be used for screening ophthalmic diseases and also monitoring patients with known diseases. Electronic ophthalmologic records of the patients including captured images by smartphones from anterior and posterior segments of the eye will be evaluated by ophthalmologists, and if patients require further evaluations, they will be referred to experts in the relevant field. Eye diseases such as cataract, glaucoma, age-related macular degeneration, diabetic retinopathy, and retinopathy of prematurity are the most common causes of blindness in many countries and beneficial use of teleophthalmology with smartphones will be a good way to achieve the aim of VISION 2020 all over the world. Numerous studies have shown that teleophthalmology is similar to the conventional eye care system in clinical outcomes and even provides more patient satisfaction as it saves time and cost. This review explains how teleophthalmology helps to improve patient outcomes through smartphones.

Reaching the Unreachable: Novel Approaches to Telemedicine Screening of Underserved Populations for Vitreoretinal Disease

Telemedicine involves electronic communication between a physician in one location and a patient in another location to provide remote medical care. Ophthalmologists are increasingly employing telemedicine, particularly in retinal disease screening and monitoring. Telemedicine has been utilized to decrease barriers to care and yield greater patient satisfaction and lower costs, while maintaining high sensitivity and specificity. This review discusses common patient barriers to eye care, innovative approaches to retinal disease screening and monitoring using telemedicine, and eye care policy initiatives needed to enact large-scale telemedicine eye disease screening programs.

PROGRESSION OF MACULAR ATROPHY IN PATIENTS WITH NEOVASCULAR AGE-RELATED MACULAR DEGENERATION UNDERGOING ANTIVASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY

PURPOSE

To define the frequency and quantify the progression of macular atrophy (MA) in patients with neovascular age-related macular degeneration undergoing treatment with antivascular endothelial growth factor therapy for >2 years.

METHODS

Fifty-four eyes of 46 patients (86.7 ± 6.8 years, 53.7% women) diagnosed with wet age-related macular degeneration were included in this retrospective study. Eyes that received photodynamic therapy or laser treatment were excluded. All eyes were imaged at baseline and after 2 years with the Cirrus spectral domain optical coherence tomography using a 512 × 128 macular cube scan protocol centered on the fovea. Optical coherence tomography en face fundus images were obtained for each 3-dimensional data set using the U.S. Food and Drug Administration-cleared Advanced RPE Analysis software, which automatically identifies atrophic areas by segmenting regions of increased reflectivity in en face choroidal slab images. Segmentation errors were manually corrected by trained Doheny Image Reading Center graders using a standardized grading protocol. The prevalence rates of atrophy at baseline and at 2-years follow-up and enlargement rates were computed. Baseline demographic factors and types and numbers of antivascular endothelial growth factor injections received over time were correlated with the development and enlargement of atrophy.

RESULTS

Macular atrophy was noted at baseline in 32 (59.3%) eyes and progressed in all eyes over the next 2 years. Among the 28 eyes without atrophy at baseline, MA developed by 2 years in 6 eyes (21.4% of eyes without MA at baseline). Of note, 22 eyes (40.7% of overall cohort) never developed atrophy during the course of the study. Among eyes with atrophy at baseline, the annual growth rate of MA was found to be 0.89 ± 0.93 mm. A multiple regression analysis was performed to evaluate the influence of gender, age, smoking status, medication injected, and number of injections on MA. Except for the number of total injections (R = 0.3, P < 0.01), the studied variables could not significantly predict development or progression of MA (F [0.73, 13] = 0.378, P = 0.86, R = 0.05). However, the study was not powered to detect small effects.

CONCLUSION

Macular atrophy is a frequent finding in eyes with wet age-related macular degeneration both before and after antivascular endothelial growth factor therapy. The frequency of new optical coherence tomography-defined atrophy (21% at 2 years) after starting therapy was close to the rates reported in CATT, IVAN, and HARBOR. The rate of MA enlargement was positively correlated with the number of injections, but did not appear to be greater than that reported for atrophy in the absence of choroidal neovascularization.

Teleretinal imaging for detection of referable macular degeneration

PURPOSE

The purpose of this study was to determine the sensitivity and specificity for detection of referable age-related macular degeneration (AMD) using an existing nonmydriatic telemedicine pathway for diabetic retinopathy screening with comparison to same-day face-to-face examination by a retina specialist.

METHODS

Subjects in this study underwent nonmydriatic and mydriatic digital retinal imaging on the same day as stereoscopic dilated examination of the macula by a retina specialist and the level of AMD was recorded for each eye. Images were graded by two trained readers as nonreferable or referable (AREDS [Age-Related Eye Disease Study] grading of level 3 or greater). Sensitivity and specificity were calculated by comparing referral recommendations between each reader and the retina specialist ("gold standard").

RESULTS

There were 47 subjects (94 eyes) enrolled in the study. Sensitivity for nonreferable AMD with nonmydriatic imaging was 1.0 (reader 1) and 1.0 (reader 2), whereas specificity was 0.75 (reader 1) and 0.91 (reader 2). Sensitivity for referable AMD with nonmydriatic imaging was 0.84 (reader 1) and 0.88 (reader 2), whereas specificity was 0.81 (reader 1) and 0.81 (reader 2).

CONCLUSIONS

Our study showed that nonmydriatic digital retinal imaging had excellent sensitivity and specificity in identifying referable and nonreferable AMD using an existing validated telemedicine pathway for diabetic retinopathy screening.

Combined Nonmydriatic Spectral-Domain Optical Coherence Tomography and Nonmydriatic Fundus Photography for the Detection of Age-Related Macular Degeneration Changes

BACKGROUND AND OBJECTIVE

Nonmydriatic fundus photography (FP) has been a suboptimal tool for detecting age-related macular degeneration (AMD) changes. This study sought to enhance the detection of AMD changes by combining nonmydriatic FP with nonmydriatic spectral-domain optical coherence tomography (SD-OCT).

PATIENTS AND METHODS

The study population included 249 patients aged 65 years and older who were assessed for AMD changes using standard mydriatic biomicroscopic fundus examination. Each eye then underwent nonmydriatic FP in one session followed 1 week later with nonmydriatic FP coupled with nonmydriatic SD-OCT. Images were interpreted for detection of AMD changes, and findings were compared to the original mydriatic biomicroscopic examination.

RESULTS

Nonmydriatic FP had 64% sensitivity, 97% specificity, and a kappa value of 0.67 in detecting AMD changes compared with the traditional mydriatic biomicroscopic examination. Combined nonmydriatic FP and nonmydriatic SD-OCT increased sensitivity to 91.5%, specificity to 98.6%, and kappa to 0.91.

CONCLUSION

The addition of nonmydriatic SD-OCT to nonmydriatic FP enhances the detection of AMD changes.

A survey of current and anticipated use of standard and specialist equipment by UK optometrists

PURPOSE

To investigate current and anticipated use of equipment and information technology (IT) in community optometric practice in the UK, and to elicit optometrists' views on adoption of specialist equipment and IT.

METHODS

An anonymous online questionnaire was developed, covering use of standard and specialist diagnostic equipment, and IT. The survey was distributed to a random sample of 1300 UK College of Optometrists members.

RESULTS

Four hundred and thirty-two responses were received (response rate = 35%). Enhanced (locally commissioned) or additional/separately contracted services were provided by 73% of respondents. Services included glaucoma repeat measures (30% of respondents), glaucoma referral refinement (22%), fast-track referral for wet age-related macular degeneration (48%), and direct cataract referral (40%). Most respondents (88%) reported using non-contact/pneumo tonometry for intra-ocular pressure measurement, with 81% using Goldmann or Perkins tonometry. The most widely used item of specialist equipment was the fundus camera (74% of respondents). Optical Coherence Tomography (OCT) was used by 15% of respondents, up from 2% in 2007. Notably, 43% of those anticipating purchasing specialist equipment in the next 12 months planned to buy an OCT. 'Paperless' records were used by 39% of respondents, and almost 80% of practices used an electronic patient record/practice management system. Variations in responses between parts of the UK reflect differences in the provision of the General Ophthalmic Services contract or community enhanced services. There was general agreement that specialised equipment enhances clinical care, permits increased involvement in enhanced services, promotes the practice and can be used as a defence in clinico-legal cases, but initial costs and ongoing maintenance can be a financial burden. Respondents generally agreed that IT facilitates administrative flow and secure exchange of health information, and promotes a state-of-the-art practice image. However, use of IT may not save examination time; its dynamic nature necessitates frequent updates and technical support; the need for adequate training is an issue; and security of data is also a concern.

CONCLUSION

UK optometrists increasingly employ modern equipment and IT services to enhance patient care and for practice management. While the clinical benefits of specialist equipment and IT are appreciated, questions remain as to whether the investment is cost-effective, and how specialist equipment and IT may be used to best advantage in community optometric practice.

Change in drusen area over time compared using spectral-domain optical coherence tomography and color fundus imaging

PURPOSE

To investigate the relationship between drusen areas measured with color fundus images (CFIs) and those with spectral-domain optical coherence tomography (SDOCT).

METHODS

Forty-two eyes from thirty patients with drusen in the absence of geographic atrophy were recruited to a prospective study. Digital color fundus images and SDOCT images were obtained at baseline and at follow-up visits at 3 and 6 months. Registered, matched circles centered on the fovea with diameters of 3 mm and 5 mm were identified on both CFIs and SDOCT images. Spectral-domain OCT drusen measurements were obtained using a commercially available proprietary algorithm. Drusen boundaries on CFIs were traced manually at the Doheny Eye Institute Image Reading Center.

RESULTS

Mean square root drusen area (SQDA) measurements for the 3-mm circles on the SDOCT images were 1.451 mm at baseline and 1.464 mm at week 26, whereas the measurements on CFIs were 1.555 mm at baseline and 1.584 mm at week 26. Mean SQDA measurements from CFIs were larger than those from the SDOCT measurements at all time points (P = 0.004 at baseline, P = 0.003 at 26 weeks). Changes in SQDA over 26 weeks measured with SDOCT were not different from those measured with CFIs (mean difference = 0.014 mm, P = 0.5).

CONCLUSIONS

Spectral-domain OCT drusen area measurements were smaller than the measurements obtained from CFIs. However, there were no differences in the change in drusen area over time between the two imaging modalities. Spectral-domain OCT measurements were considerably more sensitive in assessing drusen area changes.

Drusen measurements comparison by fundus photograph manual delineation versus optical coherence tomography retinal pigment epithelial segmentation automated analysis

PURPOSE

To compare drusen measurements obtained from color fundus and infrared retromode photographs with those derived from spectral-domain optical coherence tomography.

METHODS

Drusen lesions identified on the planar (color and infrared) imaging modalities were manually segmented by two independent graders using previously described reading center software to produce quantitative measurements of drusen area and number. The corresponding volume Cirrus OCT datasets were analyzed using commercial retinal pigment epithelium analysis algorithms to segment the retinal pigment epithelium band and estimated the drusen area. Drusen numbers were extracted from retinal pigment epithelium elevation maps. Intraclass correlation coefficients assessed agreement between graders; graders' average measurements were compared with optical coherence tomography (OCT) using paired T-tests.

RESULTS

Excellent agreement between graders was observed (r = 0.951-0.974). No statistical difference was found in the area values obtained by color (0.85 ± 0.26 mm(2), P = 0.43) or retromode (1.15 ± 0.32 mm(2), P = 0.35) compared with those obtained by OCT (0.98 ± 0.28 mm). The number of drusen identified by OCT (13.15 ± 3.19) was significantly lower than that determined by manual segmentation of color (53.7 ± 13.18) and retromode (100.13 ± 16.18) images.

CONCLUSION

Although the number of drusen individualized by commercial OCT algorithms is significantly lower than by planar fundus imaging modalities, the OCT-measured drusen area is not affected, suggesting that the algorithm counts confluent drusen as a single drusen.

Age-related macular degeneration screening using a nonmydriatic digital color fundus camera and telemedicine

PURPOSE

To investigate the use of a nonmydriatic digital color fundus camera and telemedicine as screening tools for age-related macular degeneration (AMD).

METHODS

Nonmydriatic color fundus photography was performed on patients consulting health examination centers and transmitted by telemedicine to an ophthalmology department. Rates for different grades of AMD were calculated and also statistically related to the presence or absence of risk factors.

RESULTS

Among the 1,022 patients screened, a total of 1,363 color fundus photographs were interpreted, with 80% gradable images, allowing a diagnosis of AMD in 178 photographs. Among all the gradable images, 83.7% had no AMD (grade 0). The rates of AMD at grades 1, 2, 3 and 4 were 8%, 5.6%, 2.3% and 0.4%, respectively. A statistical odds ratio was found between the presence of AMD on fundus photographs and age, familial history of AMD or prior cataract surgery.

CONCLUSIONS

Nonmydriatic color fundus photography and telemedicine succeeded in screening for AMD.

Feasibility of telemedicine in detecting diabetic retinopathy and age-related macular degeneration

Age-related macular degeneration and diabetic retinopathy are important causes of visual impairment and blindness in the world. Because of recent advances and newly available treatment modalities along with the devastating consequences associated with late stages of these diseases, much attention has been paid to the importance of early detection and improving patient access to specialist care. Telemedicine or, more specifically, digital retinal imaging utilizing telemedical technology has been proposed as an important alternative screening and management strategy to help meet this demand. In this paper, we perform a literature review and analysis that evaluates the validity and feasibility of telemedicine in detecting diabetic retinopathy and age-related macular degeneration. Understanding both the progress and barriers to progress that have been demonstrated in these two areas is important for future telemedicine research projects and innovations in telemedicine technology.

Comparison of drusen area detected by spectral domain optical coherence tomography and color fundus imaging

PURPOSE

To compare the measurements of drusen area from manual segmentation of color fundus photographs with those generated by an automated algorithm designed to detect elevations of the retinal pigment epithelium (RPE) on spectral domain optical coherence tomography (SD-OCT) images.

METHODS

Fifty eyes with drusen secondary to nonexudative age-related macular degeneration were enrolled. All eyes were imaged with a high-definition OCT instrument using a 200 × 200 A-scan raster pattern covering a 6 mm × 6 mm area centered on the fovea. Digital color fundus images were taken on the same day. Drusen were traced manually on the fundus photos by graders at the Doheny Image Reading Center, whereas quantitative OCT measurements of drusen were obtained by using a fully automated algorithm. The color fundus images were registered to the OCT data set and measurements within corresponding 3- and 5-mm circles centered at the fovea were compared.

RESULTS

The mean areas (± SD [range]) for the 3-mm circles were SD-OCT = 1.57 (± 1.08 [0.03-4.44]); 3-mm color fundus = 1.92 (± 1.08 [0.20-3.95]); 5-mm SD-OCT = 2.12 (± 1.55 [0.03-5.40]); and 5-mm color fundus = 3.38 (± 1.90 [0.39-7.49]). The mean differences between color images and the SD-OCT (color - SD-OCT) were 0.36 (± 0.93) (P = 0.008) for the 3-mm circle and 1.26 (± 1.38) (P < 0.001) for the 5-mm circle measurements. Intraclass correlation coefficients of agreements for 3- and 5-mm measurements were 0.599 and 0.540, respectively.

CONCLUSIONS

There was only fair agreement between drusen area measurements obtained from SD-OCT images and color fundus photos. Drusen area measurements on color fundus images were larger than those with SD-OCT scans. This difference can be attributed to the fact that the OCT algorithm defines drusen in terms of RPE deformations above a certain threshold, and will not include small, flat drusen and subretinal drusenoid deposits. The two approaches provide complementary information about drusen.

Fundus autofluorescence imaging in an ocular screening program

Purpose. To describe integration of fundus autofluorescence (FAF) imaging into an ocular screening program. Methods. Fifty consecutive screening participants were included in this prospective pilot imaging study. Color and FAF (530/640 nm exciter/barrier filters) images were obtained with a 15.1MP Canon nonmydriatic hybrid camera. A clinician evaluated the images on site to determine need for referral. Visual acuity (VA), intraocular pressure (IOP), and ocular pathology detected by color fundus and FAF imaging modalities were recorded. Results. Mean ± SD age was 47.4 ± 17.3 years. Fifty-two percent were female and 58% African American. Twenty-seven percent had a comprehensive ocular examination within the past year. Mean VA was 20/39 in the right eye and 20/40 in the left eye. Mean IOP was 15 mmHg bilaterally. Positive color and/or FAF findings were identified in nine (18%) individuals with diabetic retinopathy or macular edema (n = 4), focal RPE defects (n = 2), age-related macular degeneration (n = 1), central serous retinopathy (n = 1), and ocular trauma (n = 1). Conclusions. FAF was successfully integrated in our ocular screening program and aided in the identification of ocular pathology. Larger studies examining the utility of this technology in screening programs may be warranted.

Strategies for following dry age-related macular degeneration

Spectral domain optical coherence tomography (SDOCT) provides a novel strategy for imaging and monitoring progression in patients with age-related macular degeneration (AMD). The advantage of SDOCT over other imaging modalities or functional tests is that one modality can be used to image both drusen and geographic atrophy while obtaining reproducible, quantitative data on both drusen morphology and the area of geographic atrophy. Moreover, this strategy enables the clinician to follow the disease as it progresses from drusen to both geographic atrophy and choroidal neovascularization. No other imaging modality is able to quantitatively assess all forms of AMD. This unique feature of SDOCT makes it the ideal imaging modality for monitoring patients with AMD, providing routine care, and for following patients in clinical trials designed to assess the efficacy of new drugs for the treatment of dry AMD.

Microperimetric correlations of autofluorescence and optical coherence tomography imaging in dry age-related macular degeneration

PURPOSE

To investigate the microperimetric correlations of autofluorescence imaging and optical coherence tomography (OCT) in dry age-related macular degeneration (AMD).

DESIGN

Retrospective, observational, cross-sectional study.

METHODS

Consecutive patients with dry AMD underwent a complete ophthalmologic examination, including best-corrected visual acuity (BCVA), blue fundus autofluorescence (FAF), near-infrared autofluorescence, and spectral-domain (SD)-OCT with integrated microperimetry.

RESULTS

A total of 58 eyes of 29 patients (21 women; mean age 73 ± 9 years) were included. Mean BCVA was 0.28 ± 0.3 logarithm of the minimal angle of resolution (logMAR). Overall, 2842 points were analyzed as regards FAF and near-infrared autofluorescence patterns, the status of inner segment/outer segment (IS/OS) interface, and retinal sensitivity. We observed a good correlation between the FAF and near-infrared autofluorescence patterns for all the points graded (increased FAF/near-infrared autofluorescence, Pearson rho = 0.6, P = .02; decreased FAF/near-infrared autofluorescence, Pearson rho = 0.7, P = .01; normal FAF/near-infrared autofluorescence, Pearson rho = 0.7, P = .01). Mean retinal sensitivity was significantly reduced in cases of decreased FAF (4.73 ± 2.23 dB) or increased FAF (4.75 ± 2.39 dB) compared with normal FAF (7.44 ± 2.34 dB) (P = .001). Mean retinal sensitivity was significantly reduced in case of decreased near-infrared autofluorescence (3.87 ± 2.28 dB), compared with increased near-infrared autofluorescence (5.76 ± 2.44 dB) (P = .02); mean retinal sensitivity in case of increased near-infrared autofluorescence was significantly reduced compared with normal near-infrared autofluorescence (7.15 ± 2.38 dB) (P = .002). On SD-OCT, there was a high inverse correlation between retinal sensitivity and rate of disruptions in IS/OS interface (Pearson rho = -0.72, P = .001).

CONCLUSION

A reduced retinal sensitivity consistently correlates with decreased FAF/near-infrared autofluorescence and a disrupted IS/OS interface. Increased near-infrared autofluorescence may represent a useful method for detection of retinal abnormalities early in dry AMD development.

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.

Digital ocular fundus imaging: a review

Ocular fundus imaging plays a key role in monitoring the health status of the human eye. Currently, a large number of imaging modalities allow the assessment and/or quantification of ocular changes from a healthy status. This review focuses on the main digital fundus imaging modality, color fundus photography, with a brief overview of complementary techniques, such as fluorescein angiography. While focusing on two-dimensional color fundus photography, the authors address the evolution from nondigital to digital imaging and its impact on diagnosis. They also compare several studies performed along the transitional path of this technology. Retinal image processing and analysis, automated disease detection and identification of the stage of diabetic retinopathy (DR) are addressed as well. The authors emphasize the problems of image segmentation, focusing on the major landmark structures of the ocular fundus: the vascular network, optic disk and the fovea. Several proposed approaches for the automatic detection of signs of disease onset and progression, such as microaneurysms, are surveyed. A thorough comparison is conducted among different studies with regard to the number of eyes/subjects, imaging modality, fundus camera used, field of view and image resolution to identify the large variation in characteristics from one study to another. Similarly, the main features of the proposed classifications and algorithms for the automatic detection of DR are compared, thereby addressing computer-aided diagnosis and computer-aided detection for use in screening programs.

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.

Current Clinical Trials in Dry AMD and the Definition of Appropriate Clinical Outcome Measures

Currently, there is no proven drug treatment for dry age-related macular degeneration (AMD). Several different treatment strategies are being investigated, including complement inhibition, neuroprotection, and visual cycle inhibitors, and novel clinical trial endpoints are being explored. Studies have identified genetic predispositions for dry AMD associated with complement dysfunction. Consequently, complement-based therapeutic treatment modalities are promising.

Non-mydriatic single-field fundus photography for the screening of retinal diseases in an executive health clinic

BACKGROUND AND OBJECTIVE

To determine the accuracy and sensitivity of a single-field non-mydriatic digital fundus image interpreted by an ophthalmologist and performed within a primary care setting.

PATIENTS AND METHODS

Fundus photography using a digital non-mydriatic camera was performed on both eyes of 1,175 consecutive patients as part of an executive health program. All fundus images included a 45° field of the posterior pole capturing the optic nerve and macular area. Diagnostic findings were recorded and appropriate recommendations for follow-up were made. Patients were then contacted to see whether appropriate follow-up was successfully completed and chart reviews were performed to determine biomicroscopic findings.

RESULTS

Photographs were adequate in both eyes in 1,117 patients (95.1%). Examination findings were normal in both eyes in 951 (85.1%) patients. Abnormal findings were noted in either eye in 166 (14.9%) patients. The most common abnormal findings were macular degeneration (57/166, 34.3%), optic nerve cupping (45/166, 27.1%), hypertensive retinopathy (15/166, 9.0%), and choroidal nevi (10/166, 6.0%). In all patients with abnormal findings, routine follow-up ophthalmologic examination with an eye care specialist was indicated and none of the patients required urgent attention. Sensitivity was found to be 87% and stratification was performed based on the initial diagnosis. False-positive results were from confounding diagnoses rather than true false-positives.

CONCLUSION

Single-field non-mydriatic fundus photography is accurate and sensitive for screening retinal disease in a primary care setting.

Progression of geographic atrophy in age-related macular degeneration imaged with spectral domain optical coherence tomography

PURPOSE

To determine the area and enlargement rate (ER) of geographic atrophy (GA) in patients with age-related macular degeneration (AMD) using the spectral domain optical coherence tomography (SD-OCT) fundus image.

DESIGN

Prospective, longitudinal, natural history study.

PARTICIPANTS

Eighty-six eyes of 64 patients with ≥6 months of follow-up.

METHODS

Patients with GA secondary to AMD were enrolled in this study. Macular scans were performed using the Cirrus SD-OCT (Carl Zeiss Meditec, Dublin, CA). The areas of GA identified on the SD-OCT fundus images were quantified using a digitizing tablet. Reproducibility of these measurements was assessed and the ER of GA was calculated. The usefulness of performing square root transformations of the lesion area measurements was explored.

MAIN OUTCOME MEASURES

Enlargement rate of GA.

RESULTS

At baseline, 27% of eyes had a single area of GA. The mean total area at baseline was 4.59 mm(2) (1.8 disc areas [DA]). The mean follow-up time was 1.24 years. Reproducibility, as assessed with the intraclass correlation coefficient (ICC), was excellent on both the original area scale (ICC = 0.995) and the square root scale (ICC = 0.996). Intergrader differences were not an important source of variability in lesion size measurement (ICC = 0.999, 0.997). On average, the ER of GA per year was 1.2 mm(2) (0.47 DA; range, 0.01-3.62 mm(2)/year). The ER correlated with the initial area of GA (r = 0.45; P<0.001), but there were variable growth rates for any given baseline area. When the square root transformation of the lesion area measurements was used as a measure of lesion size, the ER (0.28 mm/yr) was not correlated with baseline size (r = -0.09; P = 0.40). In this cohort of lesions, no correlation was found between ER and length of follow-up. Square root transformation of the data helped to facilitate sample size estimates for controlled clinical trials involving GA.

CONCLUSIONS

The SD-OCT fundus image can be used to visualize and quantify GA. Advantages of this approach include the convenience and assurance of using a single imaging technique that permits simultaneous visualization of GA along with the loss of photoreceptors and the retinal pigment epithelium that should correlate with the loss of visual function.

Spectral domain optical coherence tomography imaging of dry age-related macular degeneration

Spectral domain optical coherence tomography is a useful new technology for imaging and measuring geographic atrophy (GA) and drusen, the hallmarks of dry age-related macular degeneration (AMD). The advantage of using this novel technique over other imaging modalities for dry AMD is that the same scan pattern can be used to image both drusen and GA while obtaining reproducible, quantitative data on both the area of GA and the morphologic features of drusen. Moreover, this strategy enables the clinician to follow the disease as it progresses from drusen to both GA and choroidal neovascularization. No other imaging modality is able to quantitatively assess all forms of AMD. This unique feature of spectral domain optical coherence tomography makes it the ideal imaging modality for clinical trials designed to assess new drugs for the treatment of dry AMD.

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.

Spectral domain optical coherence tomographic imaging of geographic atrophy

BACKGROUND AND OBJECTIVE

To compare images of geographic atrophy (GA) obtained using spectral domain optical coherence tomography (SD-OCT) with images obtained using fundus autofluorescence (FAF).

PATIENTS AND METHODS

Five eyes from patients with dry AMD were imaged using SD-OCT and FAF, and the size and shape of the GA were compared.

RESULTS

GA appears bright on SD-OCT compared with the surrounding areas with an intact retinal pigment epithelium because of increased reflectivity from the underlying choroid. SD-OCT and FAF both identified GA reproducibly, and measurement of the area of GA is comparable between the two methods with a mean difference of 2.7% of the total area.

CONCLUSION

SD-OCT can identify and quantitate areas of GA. The size and shape of these areas correlate well to the areas of GA seen on autofluorescence images; however, SD-OCT imaging also provides important cross-sectional anatomic information.

Measurement of optic disc parameters on digital fundus photographs: algorithm development and evaluation

PURPOSE

To develop and evaluate a simple and rapid algorithm for optic disc measurements on digital fundus photographs, relying on the macula-disc centre distance as a reference when converting length expressed in pixels to metric distance.

METHODS

Measurements were performed on fundus photographs from 68 normal subjects, acquired using five different cameras. The magnification factor and actual size in mum of 1 pixel was known for only one camera. The measurements from this camera were compared to corresponding measurements from a confocal scanning laser ophthalmoscope.

RESULTS

Using the described algorithm, no significant differences in mean disc or cup size were observed between the tested cameras, despite differences in magnification factor (range 0.5-2.5). There were no significant differences between disc and cup measurements obtained with the confocal scanning laser ophthalmoscope and those obtained with the described algorithm in the 20 subjects examined.

CONCLUSION

The algorithm described in the current study provided clinically relevant measurements of optic disc parameters. The final program can be used directly on the acquired images, with the examined subject still available for re-examination.