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Shearlet-Based Feature Extraction for the Detection and Classification of Age-Related Macular Degeneration in Spectral Domain Optical Coherence Tomography Images
摘要： Age-related macular degeneration (AMD) is an eye disease that usually affects central vision in people older than 50 years owing to accumulation of fluid in the macular region of the retina. Optical coherence tomography (OCT) is an imaging modality that is being widely used nowadays for the detection of abnormalities in the eye. In this work, a shearlet transformYbased method is proposed for automated detection of AMD. The 2-dimensional horizontal slices of spectral domain OCT imaging data are used as input images. Images are first converted to gray scale and denoised using bilateral filter. Denoised images are decomposed by applying shearlet transform and 10 textural features are extracted from the cooccurrence matrices of high-frequency transform coefficients. Based on these features, the OCT images are classified as normal or AMD using support vector machine and k-nearest neighbor classifiers. Results obtained using shearlet-based features are compared with that of wavelet transformYbased features. Best results are obtained when shearlet-based features are classified using support vector machine.
关键词： Shearlet transform,Wavelet transform,Support vector machine,Optical coherence tomography,K-nearest neighbor,Age-related macular degeneration
更新于2025-09-09 09:28:46
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In Vivo Quantification of Retinal Changes Associated With Drusen in Age-Related Macular Degeneration
摘要： PURPOSE. Drusen alters retinal architecture in early age-related macular degeneration (AMD). However, abnormalities also may exist in drusen-free areas of the AMD retina. This study examines retinal thickness above drusen relative to drusen-free areas in the same patient and a normal population. METHODS. Patients with early to intermediate AMD (n ? 122) or no disease (n ? 30) were examined at the Center for Eye Health. Spectral domain optical coherence tomography (SD-OCT) scans through single, isolated druse (n ? 125) or con?uent drusen (n ? 54) were obtained. The thickness of individual retinal layers was measured above the druse and in a drusen-free area, 150 lm from the drusen edge. RESULTS. Intraeye comparisons found total retinal thickness above drusen was 16 6 0.6% less than drusen-free areas. Thinning was mostly in the retinal pigment epithelium/photoreceptor layer (32 6 1% reduction) and the outer nuclear layer (22 6 1% reduction). Con?uent drusen showed similar thinning of the outer retina as well as inner retina loss (5%). Thinning was strongly correlated with drusen height, but only modestly correlated with drusen width. When compared to the normal population, retinal thickness above drusen and drusen-free areas were signi?cantly reduced. CONCLUSIONS. We con?rm outer retina thinning above drusen in early/intermediate AMD compared to drusen-free areas in the same retina or a normal population. Interestingly, drusen-free areas in AMD patients were not the same as control patients suggesting ‘‘normal’’ areas of the AMD retina are abnormal. The strong correlation between retinal thinning and drusen height, rather than width, suggests current grading systems for AMD may need re?nement.
关键词： drusen,age-related macular degeneration,optical coherence tomography,retinal thickness
更新于2025-09-09 09:28:46
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Optical coherence tomography and multifocal electroretinography of patients with advanced neovascular age-related macular degeneration before, during, and after treatment with ranibizumab
摘要： Purpose: To evaluate retinal morphology and function of patients with advanced neovascular age-related macular degeneration (AMD) before, during, and after treatment with ranibizumab. Methods: Twenty-one eyes diagnosed with advanced AMD were studied with optical coherence tomography (OCT) and multifocal electroretinography (mfERG). Three intravitreal injections of ranibizumab were administered at 1-month intervals. Evaluations were performed before the first injection (D0) and at 30 (D30), 60 (D60), and 90 days (D90) after the first injection and compared to an age-matched control group (n=21 eyes). Results: The thickness of macular retinal layers increased before treatment due to the presence of intraretinal fluid. A thick retinal pigment epithelium-choriocapillaris complex (RPE-CC) suggested the presence of choroidal neovascular membrane. Intraretinal edema decreased after treatment (P<0.01), but persisting RPE-CC thickness resulted in a subretinal scar. Three different annular retinal areas were studied with mfERG (from center to periphery: rings R1, R2, and R3). The amplitude of the first negative component (N1) decreased in R1, R2, and R3 at D30, D60, and D90 when compared with that in controls (P<0.05); the N1 implicit time was delayed in R3 at D30 (P<0.05). The amplitude of the first positive component (P1) was reduced in R1 and R2 at D30, D60, and D90 when compared with that in controls (P<0.01); the P1 implicit time was delayed in R1 at D0 and D60 (P<0.05), in R2 at D0, D30, and D90 (P<0.01), and in R3 at D30 and D60 (P<0.05). Conclusion: Ranibizumab reduces intraretinal edema, even in advanced cases. Central macular activity appeared to increase after the initiation of treatment, improving over time.
关键词： Electroretinography,optical coherence,Macular degeneration/drug therapy,Antibodies,humanized/therapeutic use,Tomography,monoclonal,Intravitreal injections
更新于2025-09-09 09:28:46
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Phenotype Characteristics of Fellow Eyes in Patients With Early Onset of Neovascular Age-Related Macular Degeneration
摘要： PURPOSE. To investigate phenotype characteristics of fellow eyes in patients with early onset of neovascular age-related macular degeneration (NVAMD). METHODS. Patients with new-onset unilateral NVAMD between 50 and 65 years (n ? 57, early-onset choroidal neovascularization [CNV] group) or >80 years (n ? 47, late-onset CNV group) or with nonneovascular AMD (n ? 98, no-CNV group) were included. Fellow eyes in both CNV groups and the eyes with the more severe AMD staging in the no-CNV group were used to evaluate number and size of macular drusen, extramacular drusen (EMD), pigmentary abnormalities, and retinal pigment epithelium (RPE) atrophy on color photographs and hyperre?ective dots (HRD) and reticular pseudodrusen (RPD) on spectral-domain optical coherence tomography (SDOCT) scans. Regression analysis was used to compare groups. RESULTS. Occurrence of >20 macular drusen was more frequent in the early-onset CNV group than the late-onset CNV group (odds ratio [OR] 2.93; P ? 0.01) or the no-CNV group (OR 2.17; P ? 0.02). Retinal pigment epithelium atrophy, RPD, and HRD appeared less frequently in the early-onset CNV group than in the late-onset CNV group (RPE atrophy: OR 0.11; P ? 0.005; RPD: OR 0.04; P ? 9.38 3 10(cid:2)10, HRD: OR 0.30; P ? 0.004) and no-CNV group (RPE atrophy: OR 0.12; P ? 0.005; RPD: OR 0.40, P ? 0.03, HRD: not signi?cant). No differences were detected regarding presence of large drusen, pigmentary abnormalities, and EMD. CONCLUSIONS. A large number of macular drusen in the fellow eye appeared to be characteristic for early onset of NVAMD, whereas RPE atrophy, HRD, and RPD were more frequently present in AMD patients > 80 years. Prospective trials with patients converting to NVAMD are required to further analyze morphologic characteristics for early versus late development of advanced AMD.
关键词： reticular pseudodrusen,fellow eye,spectral-domain optical coherence tomography,neovascular age-related macular degeneration
更新于2025-09-09 09:28:46
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Expanding the role of medical retina virtual clinics using multimodal ultra-widefield and optical coherence tomography imaging
摘要： Background: An increasingly elderly population with a corresponding increase in ophthalmic conditions has led to increased pressure on hospital eye services (HES). In this study, we evaluated the use of a medical retina virtual clinic (MRVC), which has expanded into assessing all new medical retina referrals, where the need for urgent treatment was not clear. Methods: Retrospective analysis of all new patients who were seen in the MRVC between April 2016 and May 2018. Pro forma sheets were used in the MRVC to record the patient history, visual acuity, and type of imaging required. Two consultants reviewed the completed pro formas and images and provided a final diagnosis and management plan. These results and reasons for face-to-face (F2F) clinic appointment requests were analyzed. Results: Six hundred ten new referrals were enrolled in the virtual clinic. The most common diagnosis was diabetic eye disease (59.9%). In the virtual clinic 44.1% were followed up, 28.1% were discharged, and 27.8% were booked an F2F clinic appointment (urgent/routine). The main reason for F2F clinic was to offer treatment. Urgent F2F appointments took place on average 11.9 days after virtual clinic attendance. In only two cases was the image quality felt to be inadequate to assess the retina. Conclusions: MRVC is an effective way of triaging medical retina referrals to allow those patients needing treatment to be seen promptly in the medical retinal service. The use of multimodal ultra-widefield and optical coherence tomography imaging allows assessment of a wide range of retinal pathologies and is a promising solution to alleviate the burden on HES.
关键词： teleophthalmology,diabetic retinopathy,optical coherence tomography,macular degeneration,choroidal naevus,virtual clinic
更新于2025-09-09 09:28:46
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A single-arm, investigator-initiated study of the efficacy, safety, and tolerability of intravitreal aflibercept injection in subjects with exudative age-related macular degeneration previously treated with ranibizumab or bevacizumab (ASSESS study): 12-month analysis
摘要： In subjects with active exudative age-related macular degeneration, treating with a fixed intravitreal aflibercept injection dosing regimen for 12 months demonstrated improved anatomic and vision endpoints from baseline. Purpose: Switching therapies in neovascular age-related macular degeneration (AMD) may offer an advantage for some patients. This study evaluates the efficacy of intravitreal aflibercept injection (IAI) in subjects previously treated with ranibizumab and/or bevacizumab. Methods: Subjects (n=26) were given monthly 2 mg of IAI for 3 months, followed by 2 mg once in every 2 months for up to 12 months. The mean absolute change from baseline in central subfield thickness (CST) measured by optical coherence tomography and the mean change from baseline in best-corrected visual acuity (BCVA) early treatment in diabetic retinopathy study (ETDRS) letter score were obtained. Additionally, the percentage of subjects who gained or lost $15 letters of vision and the percentage of subjects who are 20/40 or better or 20/200 or worse were evaluated. Results: There was a mean decrease in CST of ?50.3 μm (P,0.001) and a mean increase in ETDRS BCVA of +9.2 letters (P,0.001). Twenty-seven percent of subjects experienced a $15-letter improvement in visual acuity, and no subject lost $3 lines of vision from baseline. Fifty percent of subjects were 20/40 or better, and 11.5% of subjects were 20/200 or worse at month 12. Conclusion: Fixed IAI dosing regimen for 12 months demonstrated improved anatomic and vision endpoints in subjects with active exudative AMD.
关键词： bevacizumab,aflibercept,vascular endothelial growth factors,ranibizumab,age-related macular degeneration
更新于2025-09-09 09:28:46
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Retinal metabolic and structural alterations in response to aflibercept treatment in neovascular age‐related macular degeneration
摘要： Purpose: Non-invasive retinal markers of disease activity could pave the way for individualized treatment in neovascular age-related macular degeneration (nAMD). We aimed to evaluate if retinal vascular oxygen saturation and calibres could predict the initial treatment response after a loading phase of intravitreal a?ibercept in nAMD. Method: A total of 149 eyes were included (nAMD, n = 76; dry AMD, n = 30; normal eyes n = 43). Of these, 57 treatment-na€?ve eyes with nAMD received three monthly injections with 2.0 mg a?ibercept and were subsequently strati?ed according to functional and structural response according to development in best-corrected visual acuity and macular retinal thickness. The retinal vascular oxygen saturation and calibres were measured prior to treatment and 1 month after the third injection. Results: Patients with nAMD and dry AMD had higher retinal arteriolar oxygen saturation as compared to normal eyes (94.3% versus 95.2% versus 92.6%, p = 0.04). Thirty-nine (68.4%) and 12 (21.1%) eyes with nAMD were functional and structural responders. After the loading phase, structural nonresponders developed a higher retinal arteriolar (95.3% versus 93.3%, p = 0.03) and venular (64.7% versus 59.4%, p = 0.02) oxygen saturation, and responders developed a lower retinal arteriolar calibre (118.0 versus 114.3 lm, p < 0.01). In a multiple logistic regression model, increasing retinal venular oxygen saturation associated with a negative structural treatment outcome (odds ratio 1.17 for each 1% increment after the loading phase, 95% con?dence interval 1.01–1.36, p = 0.03). Conclusion: Changes in the retinal venular oxygen saturation associate independently with initial treatment response in nAMD, but functional and structural retinal measurements prior to treatment could not predict the treatment response.
关键词： a?ibercept,retinal vascular calibre,disease activity,neovascular age-related macular degeneration,retinal oximetry,choroidal neovascularization
更新于2025-09-09 09:28:46
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Targeting modifiable risk factors in age-related macular degeneration in optometric practice in Sweden
摘要： The purpose of this study was to investigate the extent to which ophthalmologists and optometrists in Sweden recommend the use of nutritional supplements, changes in diet, or smoking cessation to patients who are at risk of or with signs of age-related macular degeneration (AMD). In addition, this study also examined how these practitioners rate the strength of evidence for nutritional supplements in AMD management and which sources of information they consult to determine supplement recommendations for the prevention or treatment of AMD. Methods: This study implemented a cross-sectional design using data from a questionnaire. All Swedish optometrists and ophthalmologists who were registered in the membership databases of their respective professional organizations were invited to participate. The questionnaire contained 18 forced choice questions and one free text question and was organized into the following four sections: use of nutritional supplements, dietary advice, smoking and eye diseases, and strength of evidence and the sources of information regarding nutritional supplement interventions. Results: The response rate was 40.3% for optometrists and 5% for ophthalmologists. Optometrists were more likely than ophthalmologists to recommend nutritional supplements in AMD and provided significantly more advice about diet than did the ophthalmologists for both patients at risk for AMD and those with established disease. The ophthalmologists were more likely than the optometrists to rely on the findings from the age-related eye disease studies of AMD regarding treatment with and selection of supplements and to recommend smoking cessation. Conclusion: Common evidence-based strategies for AMD management among eye care professionals would presumably be beneficial for AMD patients. Targeted education and implementation strategies may be needed.
关键词： diet,nutritional supplements,smoking,age-related macular degeneration
更新于2025-09-04 15:30:14
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Longitudinal Associations Between Microstructural Changes and Microperimetry in the Early Stages of Age-Related Macular Degeneration
摘要： PURPOSE. To determine whether longitudinal changes in mesopic visual function on microperimetry occurred independent of its associations with microstructural parameters on spectral-domain optical coherence tomography (SD-OCT) in the early stages of AMD. METHODS. Forty-one AMD eyes underwent microperimetry testing and SD-OCT scans over a 12-month period at 6-month intervals. Microstructural parameters analyzed include the retinal pigment epithelium-drusen complex (RPEDC) layer thickness, number of hyperre?ective foci (HF) and their inner retinal migration (represented by a weighted axial distribution score; AxD), and the number of atrophic areas. RESULTS. Microperimetric sensitivity was 0.29 dB (95% con?dence interval [CI] ? (cid:2)0.38 to (cid:2)0.20 dB, P < 0.001) and 0.13 dB (95% CI ? (cid:2)0.22 to (cid:2)0.03 dB, P ? 0.008) lower in each sector for every 10-lm higher RPEDC layer thickness and 1-HF present, but was not associated with the AxD score or the number of atrophic areas present (P (cid:3) 0.464). However, each 10- lm greater RPEDC layer thickness and 1-HF present was not independently associated with a further decline in sensitivity ((cid:2)0.08 dB/year, 95% CI ? (cid:2)0.24 to 0.07 dB/year, P ? 0.288 and 0.09 dB/year, 95% CI ? (cid:2)0.06 to 0.24 dB/year, P ? 0.242, respectively) over time when accounting for the association between RPEDC layer thickness and number of HF with microperimetric sensitivity. CONCLUSIONS. Longitudinal changes in mesopic visual function measured on microperimetry paralleled changes in the microstructural changes over a 12-month time frame, without any changes occurring independent of the associations between structure and function alone.
关键词： age-related macular degeneration,optical coherence tomography,microperimetry,longitudinal
更新于2025-09-04 15:30:14
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The outcomes of aflibercept therapy in patients with age-related macular degeneration resistant to bevacizumab or ranibizumab
摘要： Purpose: This study was designed to assess the functional and anatomic outcomes of intravitreal a?ibercept injection in patients with wet age-related macular degeneration (AMD) refractory to intravitreal bevacizumab or ranibizumab therapy. Methods: This retrospective study included 43 eyes of 43 patients resistant to treatment with at least 6 injections of bevacizumab or ranibizumab. Persistent intraretinal and subretinal ?uid (IRF and SRF) on optical coherence tomography (OCT), no improvement in best corrected visual acuity (BCVA), and a central macular thickness (CMT) increase of more than 100 mm due to SRF and/or IRF compared to baseline for at least 6 monthly intravitreal bevacizumab or ranibizumab injections were de?ned as resistant to bevacizumab/ranibizumab therapy. BCVA, intraocular pressure (IOP), CMT, maximum retinal thickness (MRT), and maximum pigment epithelial detachment (PED) height (MPEDH) were evaluated before and after a?ibercept injections. Result: After initiating a?ibercept treatment, the mean ?nal BCVA logarithm of the minimum angle of resolution or recognition (logMAR) improved to 0.84 ± 0.59 which was statistically signi?cant compared to baseline (1.14 ± 0.51), (P < 0.001). After a?ibercept injection, statistically signi?cant reduction was noted in mean CMT (402.6 ± 196.7 mm vs 264.2 ± 52.85 mm, P < 0.05), MRT (435.3 ± 195.2 mm vs 282.2 ± 31.8 mm, P < 0.05), and MPEDH (154.2 ± 86.0 mm vs 68.3 ± 70.6 mm, P < 0.05). There was no correlation between the total number of previous injections and the increase of BCVA (r ? (cid:2)0.10, P ? 0.265). The decrease of mean IOP was statistically signi?cant under a?ibercept treatment (P < 0.001). Conclusions: The present study showed the ef?cacy of a?ibercept treatment in eyes with persistent retinal or SRF under bevacizumab or ranibizumab therapy. A signi?cant anatomical and functional improvement was noted.
关键词： A?ibercept,Age related macular degeneration,Bevacizumab,Ranibizumab,Anti-vascular endothelial growth factor
更新于2025-09-04 15:30:14