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Background/objectives: To characterise morphological changes in neovascular age-related macular degeneration (nAMD) during anti-angiogenic therapy and explore relationships with best-corrected visual acuity (BCVA) and development of macular atrophy (MA)., Subjects/methods: Post-hoc analysis of the phase III HARBOR trial. SD-OCT scans from 1097 treatment-naïve nAMD eyes were analysed. Volumes of intraretinal cystoid fluid (ICF), subretinal hyperreflective material (SHRM), subretinal fluid (SRF), pigment epithelial detachment (PED) and cyst-free retinal volume (CFRV) were measured by deep-learning model. Volumes were analysed by treatment regimen, macular neovascularisation (MNV) subtypes and topographic location. Associations of volumetric features with BCVA and MA development were quantified at month 12/24., Results: Differences in feature volume changes by treatment regimens and MNV subtypes were observed. Each additional 100 nanolitre unit (AHNU) of residual ICF, SHRM and CFRV at month 1 in the fovea was associated with deficits of 10.3, 7.3 and 12.2 letters at month 12. Baseline AHNUs of ICF, CFRV and PED were associated with increased odds of MA development at month 12 by 10%, 4% and 3%. While that of SRF was associated with a decrease in odds of 5%. Associations at month 24 were similar to those at month 12., Conclusion: Eyes with different MNV subtypes showed distinct trajectories of feature volume response to treatment. Higher baseline volumes of ICF or PED and lower baseline volume of SRF were associated with higher likelihoods of MA development over 24 months. Residual intraretinal fluid, including ICF and CFRV, along with SHRM were predictors of poor visual outcomes., (© 2024. The Author(s).)

Objectives: To determine the associations between the presence of various-sized hypertransmission defects (hyperTDs) and progression to incomplete retinal pigment epithelial (RPE) and outer retinal atrophy (iRORA) and complete RORA (cRORA) in eyes with intermediate age-related macular degeneration (iAMD)., Methods: Optical coherence tomography (OCT) data from consecutive iAMD patients, were retrospectively reviewed. All of iAMD eyes with or without iRORA (but not cRORA) at baseline were included. Graders evaluated the presence of hyperTDs at baseline (small: 63-124 µm; medium: 125-249 µm; large: ≥ 250 µm in diameter on choroidal en face OCT) and the progression two years later., Results: Of the 145 eyes that not developed neovascular AMD at two years, the eyes that progressed to or developed iRORA or cRORA included 13 eyes (10.7%), 5 eyes (83.3%), 9 eyes (81.8%), and 6 eyes (85.7%) in the groups with no, small, medium, and large hyperTDs at baseline, respectively (P-value < 0.001). The odds ratios (95% CI) for progression were 41.6 (4.5-383.6), 37.4 (7.3-192.0), and 49.9 (5.6-447.1) in the small, medium, and large hyperTDs groups, compared to no hyperTDs (P-value ≤ 0.001). Eyes with ≥ 2 hyperTDs also showed more frequent progression than eyes with one or no hyperTDs (100% vs. 16.4%; P-value < 0.001)., Conclusions: While most iAMD eyes with no hyperTDs remained stable on OCT over two years, eyes with hyperTDs of any size appeared to be at a higher risk for progression. HyperTDs may provide an important OCT biomarker for identifying high-risk iAMD patients., (© 2024. The Author(s).)

Objective: To evaluate the effect of changing slab position on the correlation between choriocapillaris (CC) flow deficits (FD) in eyes with geographic atrophy (GA) and yearly enlargement rate (yER) of GA., Methods: OCT and OCTA images obtained on Cirrus HD-OCT device were collected from patients with GA. Each patient underwent OCTA scan at baseline and two OCT scans, one at baseline and one after at least 12 months. GA was delineated on en-face fundus image to calculate yER. OCTA images were generated from three 10 µm thick slabs 11, 21 and 31 µm posterior to RPE-fit line. 100 µm-wide concentric rings were generated around GA to calculate FD% in each ring which was correlated with yER., Results: For the 11-21 µm slab, FD% was not significantly correlated with yER for any of the rings (p > 0.05). For the 21-31 and 31-41 µm slab, FD% of rings located in the 600 µm region around GA was significantly correlated with yER (p < 0.05). However, in all slab locations, there was no significant correlation between yER and CC FD% of rings located beyond the 600 µm region (p > 0.05)., Conclusions: Slab selection for quantification of CC FD% may have a significant impact on quantitative results in eyes with GA., (© 2023. The Author(s).)

Objectives: To compare the diabetic retinopathy (DR) severity level determined when considering only the ETDRS 7-field region versus the entire ultrawidefield (UWF) image., Methods: In this retrospective, cross-sectional study, UWF pseudocolor images were graded on the Eyenuk image viewing, grading, and annotation platform for the severity of DR considering only the regions within the ETDRS 7-fields as well as the entire UWF image using two different protocols: 1) the simple International Classification of Diabetic Retinopathy (ICDR) scale and 2) the more complex DRCR.net Protocol AA grading scale., Results: A total of 250 eyes from 157 patients were included in this analysis. Six eyes (2.4%) demonstrated a discrepancy in severity level between the ETDRS 7-field region and the entire UWF image when using the ICDR classification system. The discrepancies were due to the presence of lesions [intraretinal haemorrhage (n = 2), neovascular disease (n = 4)] in the peripheral fields which were not identified in the ETDRS 7-fields. Fourteen eyes (5.6%) had a discrepancy in severity level between the ETDRS 7-field region and the entire UWF image when using the ETDRS DRSS Protocol AA grading scale. The discrepancies were due to the presence of a higher level of disease [intraretinal haemorrhage (n = 4), neovascularization (n = 4), preretinal haemorrhage (n = 2), scatter laser scars (n = 4)] in the peripheral fields., Conclusion: Although considering regions outside of the ETDRS 7-fields altered the DR severity level assessment in <5% of cases in this cohort, significant and potentially vision-threatening lesions including neovascularization and preretinal haemorrhage were identified in these peripheral regions. This highlights the importance of evaluating the entire UWF region when assessing patients with diabetic retinopathy., (© 2023. The Author(s).)

Purpose: To determine the relationship between baseline retinal non-perfusion area (NPA) and retinal vascular bed area (RVBA) on ultra-wide field fluorescein angiography (UWF FA) and long-term response to intravitreal ranibizumab therapy in diabetic macular oedema (DMO)., Methods: A post-hoc, 2-year observational case series. Baseline UWF FA images (Optos 200Tx) of 40 eyes from 29 patients with diabetes mellitus and treatment naïve DMO in the DAVE (NCT01552408) study were montaged and stereographically projected at the Doheny Image Reading Center to adjust for peripheral distortion. The retinal vasculature was automatically extracted to calculate RVBA. NPA was manually delineated by two masked certified graders. RVBA and NPA were computed in mm 2 automatically by adjusting for peripheral distortion and then correlated with the severity of DMO., Results: While global NPA at baseline was not correlated to retinal thickness measurements, baseline NPA in the superior retina was associated with the macular volume (MV) improvement (P = 0.022). Multivariate analysis revealed a smaller RVBA at baseline was correlated with a better MV outcome at two-year follow-up after adjusting for confounding factors (P = 0.049)., Conclusion: Eyes with smaller baseline RVBA appear to have a better long-term anatomic outcome of DMO., (© 2022. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Aim: To assess the macular capillary networks and foveal avascular zone (FAZ) with swept-source optical coherence tomography angiography in healthy eyes., Methods: This cross-sectional, prospective, observational study enrolled 222 eyes of 116 healthy participants with no ocular or systemic disease. SS-OCTA images were captured using the PLEX Elite 9000 (Carl Zeiss Meditec Inc., Dublin, CA, USA) with a 6 × 6 mm pattern centered on the foveal center. Vessel length density (VLD), perfusion density (PD), and FAZ parameters were analyzed using the manufacturer's automated software., Results: A significant negative correlation was observed between age and average VLD in the superficial plexus, and average PD in both the superficial plexus and the whole retina. A significant positive correlation between age and foveal avascular zone perimeter and area was also noted. Age-wise comparisons showed a trend for an increase in VLD and PD until 40 years of age, with a subsequent decrease in the older age in the macular region. The central subfield showed a decrease in the vessel density measurements in the 21-40 age group. FAZ area and perimeter were the mirror inverse of the central subfield vessel density measurements with a numerically greater area and perimeter in the 21-40 age group compared to the 0-20 and 41-60 age groups. FAZ circularity was significantly reduced after 40 years of age., Conclusion: Age-related changes in the vessel density and FAZ parameters in the healthy macula are complex and vary with the macular location. These results carry significance when interpreting the data from diseased eyes., (© 2022. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Purpose: To evaluate the ability of retro mode illumination imaging for quantifying atrophy compared to confocal color fundus photography (c-CFP), green light fundus autofluorescence (G-FAF), blue light fundus autofluorescence (B-FAF) using the scanning laser ophthalmoscope (SLO) Mirante device by Nidek (Nidek Co., Ltd, Gamogori, Japan)., Methods: Eyes with clinical evidence of geographic atrophy (GA) associated with non-neovascular age-related macular degeneration, evaluated at the Doheny Eye Centers-UCLA and Hospital Sacco Milan, were included in this prospective, cross-sectional study. All eyes were imaged with multiple retinal imaging modalities using the SLO Nidek Mirante device: c-CFP, G-FAF, B-FAF, retro mode illumination deviated-right (RMDR), and deviated-left (RMDL). Masked graders measured the GA lesion on each modality and inter-modality and inter-grader repeatability were assessed., Results: The mean (SD) area of GA measured 9.76 (3.82) mm 2 , 9.75 (3.91) mm 2 , 9.76 (3.92) mm 2 , 9.82 (3.87) mm 2 , and 9.81 (3.86) mm 2 using c-CFP, G-FAF, B-FAF, RMDR, and RMDL, respectively (p = 0.2). Inter-modality correlation was high (Pearson's r > 0.9 and p < 0.0001). Agreement between graders was excellent for all modalities., Conclusions: Retro mode imaging demonstrated good agreement for measuring GA compared to other imaging modalities, with a high level of repeatability. Given that retro mode imaging uses infrared light and is comfortable, it may prove to be a useful tool for the assessment of GA in the clinic., (© 2021. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Diabetic retinopathy is a major cause of vision loss worldwide and areas of retinal non-perfusion (RNP) are a key pathologic feature of the vascular component of diabetic retinopathy. While there is a need for a more complete understanding of the natural history of RNP development and progression, overall, increasing RNP has been closely linked with worsening DR severity. Both traditional and novel approaches to quantitative image assessment are being explored to advance our understanding of the vascular, physiologic and functional changes associated with progressive RNP. Retinal ischemia secondary to RNP leads to tissue hypoxia and changes in the expression of a host of signalling molecules. Current anti-vascular endothelial growth factor and steroid pharmaceutical agents appear to be unable to reperuse areas of RNP, but may be able to slow the progressive longitudinal accumulation of RNP with regular retreatments. There remains a tremendous unmet need for pharmacotherapies that can slow RNP progression and ultimately reperfuse areas of the non-perfused retina. Towards this end, novel targets including the semaphorin family are being investigated., (© 2021. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Background/objectives: To evaluate biometric changes throughout the anterior chamber during accommodation and presbyopia using single image acquisition swept-source anterior-segment optical coherence tomography (AS-OCT)., Subject/methods: Anterior-segment images were obtained using a new swept-source AS-OCT device (ANTERION, Heidelberg Engineering) from healthy volunteers (n = 71) across two centers in this prospective observational case series. In one image acquisition, cornea through posterior lens, including the ciliary muscle on both sides of the right eye, was imaged. Subjects undertook no accommodative effort and -1, -3, and -5 D of target vergence. Two-way repeated measures ANOVA modeling was performed for ciliary muscle measurements, lens parameters, aqueous depth (AD), and pupil diameter (PD). The first ANOVA factor was accommodative stimuli, and the second factor included age and refractive status., Results: Maximum ciliary muscle thickness increased with accommodative stimuli (p < 0.001), while the distance from the scleral spur to the maximal point on the ciliary muscle and posterior ciliary muscle thickness (CMT2) decreased (p < 0.001-0.002). Older individuals showed no accommodative changes for ciliary muscle parameters, lens thickness, lens vault, PD, and AD (p = 0.07-0.32). Younger- and middle-aged eyes showed statistically significant accommodative structural alterations for these endpoints (p < 0.001-0.002), but with different patterns, including early loss of CMT2 contraction in middle-aged eyes. Within the middle-aged group, myopic eyes maintained better capacity for accommodative structural change., Conclusions: Swept-source AS-OCT demonstrated multiple simultaneous anterior-segment biometric alterations in single acquisition images, including early loss of posterior ciliary muscle function and better maintained capacity for anterior-segment structural change in myopia., (© 2021. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Purpose: To evaluate the choriocapillaris (CC) flow deficit (FD) in eyes with stable intermediate age-related macular degeneration (AMD) eyes over 12 months of follow-up., Methods: Thirty four patients with intermediate AMD were prospectively enrolled and evaluated by swept-source optical coherence tomography (SS-OCT) and OCT-angiography (OCTA) using the PLEX-Elite 9000. A 6 × 6 mm foveal-centered scan was used for both modalities and the study eyes were scanned twice to allow subsequent averaging. En face OCTA CC slabs (31-41 µm below the RPE-band) were exported and compensated for signal attenuation. Two compensated CC en-face images were registered and averaged prior to binarization and CC FD computation. The CC FD of the entire 6 × 6 macular region was quantified at baseline and at 12-months. The presence of high-risk features, namely intraretinal hyper-reflective foci (HRF), subretinal drusenoid deposits (SDD), and hyporeflective-core-drusen, were evaluated using SS-OCT volume scans., Results: Among the 34 eyes, 25 eyes from 25 patients were noted on exam and OCT to remain stable as intermediate AMD at 12-months without the development of late AMD. Eleven eyes had high-risk features at baseline compared to 14 eyes at the end of the follow-up (p = 0.094). The mean ± SD FD% across the whole 6 × 6 macular region at baseline was 19.32 ± 4.64% and significantly increased to 28.62 ± 4.71% at the end of the study (p = 0.001). The CC FD progressed significantly both in non-HR and HR-eyes., Conclusions: Choriocapillaris flow impairment significantly deteriorated over one year in relatively stable intermediate AMD. This might suggest that underlying progression of CC dysfunction occurs before structural changes appears on OCT and lead to the progression to late-stage AMD., (© 2021. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Background: Although an optical coherence tomography (OCT)-derived central drusen volume ≥0.03 mm 3 has been found to be a risk factor for progression to late age-related macular degeneration (AMD), this parameter is not currently available on most OCT devices or acquisition protocols. The purpose of this study was to evaluate the ability of human graders to qualitatively assess drusen volume by inspection of OCT B-scans., Methods: 100 subjects (200 eyes) from the Amish Eye Study diagnosed with early or intermediate AMD underwent OCT imaging with both Cirrus OCT and Spectralis OCT. Drusen volume was automatically computed from the Cirrus OCT volumes using the Cirrus Advanced RPE Analysis software. Spectralis volume scans were reviewed by two independent, masked graders who were asked to determine whether the central drusen volume was ≥0.03 mm 3 . Cohen's kappa coefficients were computed to assess the agreement., Results: After excluding 11 eyes with poor image quality and 5 eyes used for training of the graders, the remaining 184 eyes were included in this analysis. The agreement between the graders and the automated evaluation of drusen volume by the Cirrus OCT was excellent with K = 0.88 for grader 1 and K = 0.82 for grader 2. The agreement between graders was also excellent with a K = 0.88., Conclusions: The presence of a high central drusen volume can be assessed reliably by qualitative inspection of OCT B-scans. This approach may be useful in the assessment of risk for progression to late AMD., (© 2020. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

The advent of optical coherence tomography angiography (OCTA) has allowed a qualitative and quantitative analysis of the retinal vasculature and the choriocapillaris. With the use of OCTA, several studies evaluated the changes in the choriocapillaris showing how this vascular structure plays a significant role in the pathogenesis of different conditions. This article reviews the current methods of analysis of the choriocapillaris and the relevant findings in different chorioretinal diseases.

Background/objectives: This post hoc analysis explores the relationship between residual oedema exposure after ranibizumab treatment initiation and long-term visual acuity outcome in eyes with centre-involved diabetic macular oedema (DMO)., Subjects/methods: Eyes randomised to the ranibizumab + prompt or deferred laser treatment arms in the Protocol I trial and with observed central retinal thickness (CRT) readings at baseline and ≥1 follow-up visits (n = 367) were stratified by 1) oedema duration (number of study visits with CRT ≥ 250 µm during the first 52 weeks of ranibizumab treatment); and 2) oedema extent (amount of excess CRT [≥ 250 µm] at each study visit, averaged over the first 52 weeks). Associations between measures of residual oedema and best-corrected visual acuity (BCVA) were assessed in multiple regression analyses., Results: Oedema duration and oedema extent during the first 52 weeks of ranibizumab treatment showed significant negative associations with BCVA improvement at weeks 52, 104 and 156. Eyes with the most persistent oedema gained (mean) 4.4 (95% CI 0.1─8.7) fewer Early Treatment Diabetic Retinopathy Study (ETDRS) letters at week 156 than eyes with the least persistent oedema (P = 0.044). Eyes with the greatest amount of oedema gained (mean) 9.3 (95% CI 4.0─14.5) fewer ETDRS letters at week 156 than eyes with the least amount of oedema (P < 0.001)., Conclusions: Macular oedema exposure over the first 52 weeks of ranibizumab treatment is a negative prognostic factor for long-term visual acuity improvement in centre-involved DMO.

Purpose: To investigate fluorescence lifetime imaging ophthalmoscopy (FLIO) findings in preclinical Alzheimer's disease (AD)., Methods: This prospective, observational study enrolled patients with early AD undergoing Alzheimer's biomarker analysis and matched controls. Alzheimer-associated parameters (β-amyloid [Aβ], total tau in cerebrospinal fluid [CSF], Mini-Mental Status Examination [MMSE], etc.), risk factor-associated data (body mass index [BMI], hypertension, lipid profile, etc.), ganglion cell layer plus inner plexiform layer (GCIPL) thickness in structural optical coherence tomography (OCT), OCT angiography data, and FLIO-derived parameters (τ m , τ 1 , τ 2 , and τ 3 ) in short and long spectral channels (SSC and LSC) were compared and correlated between the two groups. Additional analyses were performed separately within subgroups of phakic and pseudophakic., Results: A total of 28 eyes from 15 subjects (8 control and 7 AD) were included in this analysis. In FLIO parameters, τ m in AD group showed longer lifetimes compared to the controls in phakic subjects (593.9 ± 93.3, 454.4 ± 38.6 ps; 475.0 ± 71.6, 394.1 ± 28.2  ps in SSC and LSC of AD and control groups, respectively, p = 0.036 and 0.024). Aβ, tau in CSF, and GCIPL thickness correlated with τ m in the LSC for phakic subjects (r = -0.611 to 0.562, p < 0.05 for all), but only the GCIPL thickness showed a correlation with FLIO parameters in pseudophakic subjects (r = -0.893 to -0.795, p < 0.001 for all)., Conclusion: FLIO-derived parameters appear to correlate with Aβ, tau levels in the CSF, and GCIPL thickness on OCT in AD patients. If these findings can be validated in future longitudinal studies, FLIO may prove to be useful as a simple, non-invasive diagnostic tool for AD.

PurposeTo assess the influence of varying B-scan frame-sampling densities on retinal thickness and volume measurements from spectral domain optical coherence tomography (OCT) in eyes with neovascular age-related macular degeneration (AMD).MethodsVolume OCT data (512 × 128 macular cube over 6 × 6 mm) were collected from 39 eyes with neovascular AMD. All 128 B-scans in each image set were manually segmented, allowing quantification of the neurosensory retina, subretinal fluid (SRF), subretinal hyperreflective material (SRHM), and pigment epithelium detachment (PED). Thickness maps were generated for less dense subsets of scans, ranging from every other (64 B-scans) to every 64th (2 B-scans). For each less dense subset, foveal central subfield thickness and total macular volume (TMV) were compared with values obtained using all 128 scans (considered the reference).ResultsFor each parameter, the mean absolute difference compared with the reference increased with reducing B-scan density. However, these differences did not reach statistical significance until frame-sampling density was reduced to every eighth scan (ie, 16 B-scans spaced 375 μm apart) for neurosensory retina, and every fourth scan (ie, 32 B-scans spaced 188 μm apart) for SRF, SRHM, and PED. For neurosensory retina, the mean (% error) and maximum (% error) absolute differences in TMV were 0.02 mm 3 (0.24%) and 0.06 mm 3 (0.79%), respectively. Similarly, at a density of 32 B-scans, mean and maximum differences for SRF were 0.004 mm 3 (3.47%) and 0.02 mm 3 (22.22%), respectively. The mean differences for SRHM and PED were 0.01 mm 3 (8.03%) and 0.01 mm 3 (4.04%), respectively.ConclusionsA minimum of 16 equally spaced B-scans, covering a 6 × 6 mm area, appears necessary to generate retinal thickness measurements similar to those obtained using all 128 B-scans in eyes with choroidal neovascularization (CNV). When considering other CNV lesion features, a minimum of 16 B-scans for SRF and PED, and 32 B-scans for SRHM are required to generate volume maps similar to ground-truth values. These findings may have implications for the design of acquisition and grading protocols for clinical trials using OCT in neovascular AMD.

Purpose: To study the precise structural aspects of a type 2 neovascular membrane in a patient with age-related macular degeneration (AMD) using optical coherence tomography (OCT) angiography and perform sequential quantitative analysis of the membrane after ranibizumab therapy., Patients and Methods: Split-spectrum amplitude-decorrelation (SSADA) OCT angiography macular cubes (3 × 3 mm) were acquired with a light source centered at 840 nm, a bandwidth of 45 nm, and an A-scan-rate of 70 000 scans per second. Visible pathologic vessels were outlined manually on average intensity projection en face images, and the area of the lesion and the vessel density were measured at baseline and follow-up., Results: At baseline, the neovascular lesion measured 4.12 mm(2) and the vessel density was 19.83 mm(-1). Four weeks after the first, and 2 and 4 weeks after the second ranibizumab injection, OCT angiography revealed a progressively smaller vascular lesion (2.32, 1.77 and 1.64 mm(2)), and vessel density (10.24, 8.52 and 7.57 mm(-1)), although the large central trunks of the lesion were unchanged., Conclusions: In this study, an obvious reduction in size and vessel density of the neovascular lesion was noted after treatment with ranibizumab using SSADA OCT angiography technology. Microvascular components can be delineated with precision, suggesting that this technique may be useful for the management of patients with neovascular AMD in a clinical setting as well as for future clinical trials.

Purpose: To evaluate the impact of reducing B-scan frame-sampling density on retinal thickness measurements using spectral domain optical coherence tomography (SD-OCT) in eyes with diabetic macular edema (DME)., Methods: We retrospectively collected OCT data for 64 eyes of 43 patients undergoing imaging for DME using the Cirrus HD-OCT 512 × 128 macular cube protocol. For each case, raw OCT data were imported into the 3D-OCTOR software, and retinal thickness maps were generated using all 128 B-scans and for lower densities of B-scans ranging from every other scan to only four scans (every 30-s B-scan). Maps were generated before and after manual correction of retinal boundary segmentation errors. The foveal central subfield (FCS) and total macular volume (TMV) values were used to compare thickness maps of varying densities., Results: The mean difference in FCS retinal thickness and TMV increased as the B-scan density was reduced, particularly when the density was reduced to fewer than 16 B-scans over 6 mm. At a density of 16 B-scans, the mean absolute difference in FCS thickness was 2.43 μm (0.79%), with a maximum of 10.1 μm (4.09%). At this density, the mean difference in TMV was 0.012 mm(3) (0.13%), with a maximum difference of 0.04 mm(3) (0.47%). Manual correction of OCT segmentation errors resulted in a difference in FCS thickness of ≥ 10 μm in only 12.5% of cases, with a maximum difference of 115.7 μm., Conclusion: A minimum of 16 equally spaced B-scans appear necessary to generate retinal thickness measurements similar to those produced using all 128 B-scans in eyes with DME. Manual correction of segmentation errors appeared to have a clinically meaningful effect in a small minority of cases. These results may have implications for the design of SD-OCT imaging and grading protocols in clinical trials of DME, particularly when using multiple SD-OCT instruments that acquire varying numbers of B-scans.

Since its first description more than 40 years ago, fluorescein angiography had a crucial role in the diagnosis and management of chorioretinal vascular disorders such as neovascular age-related macular degeneration. Although fluorescein angiography permits visualization of the retinal microcirculation in exquisite detail, visualization of the choroidal circulation is more limited. Moreover, fluorescein angiography provides only minimal information regarding the functional consequences of vascular disease and allows, at best, only semi-quantitative assessment of retinal thickness. In recent years, the development of other chorioretinal imaging modalities, such as indocyanine green angiography, fundus autofluorescence, and optical coherence tomography (OCT), has addressed many of these issues. In particular, OCT has become an integral tool for vitreoretinal specialists as it allows high-resolution cross-sectional images of the neurosensory retina to be obtained in a non-invasive manner. The latest generation of commercial OCT technology-spectral domain OCT-offers high-speed scanning that allows complete coverage of the macular area, generation of three-dimensional retinal reconstructions, and precise image registration for inter-visit comparisons. The high speed of spectral domain OCT also facilitates B-scan averaging, which reduces speckle noise artefact and allows unparalleled visualization of the outer retina and choroid. In the near future, further advances in OCT technology (eg Doppler OCT) are likely to dramatically enhance the diagnosis and management of patients with chorioretinal vascular disease.