Reproducibility of segmentation error correction in age-related macular degeneration: Stratus versus Cirrus OCT

Reproducibility of Measurements of Retinal Structural Parameters Using Optical Coherence Tomography in Stargardt Disease

Purpose

To assess the reproducibility of retinal measurements from optical coherence tomography (OCT) in ABCA4-related Stargardt disease (STGD1).

Methods

The international multicenter Progression of Atrophy Secondary to Stargardt Disease (ProgStar) Study enrolled 259 STGD1 patients. OCT images were graded by the study reading center (RC). Semiautomatic segmentation with manual adjustments was used to segment the layers of retinal pigmentation epithelium, outer segments, inner segments (ISs), outer nuclear layer (ONL), inner retina, and the total retina (TR). The images were overlaid to the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. For each layer, the thickness and the intact area of the ETDRS central subfield, inner ring, and outer ring were recorded, respectively. A different set of RC graders regraded 30 independent ProgStar images to evaluate measurement reproducibility. Reproducibility was assessed graphically and using statistics including intraclass correlation (ICC) and relative absolute difference (RAD).

Results

Across all layers, measurements of the ETDRS central subfield had low ICC and/or large RAD. The outer-ring region was not fully captured in some images. For inner ring, good reproducibility was observed for intact area in the IS (ICC = 0.99, RAD = 4%), thicknesses of the ONL (ICC = 0.93, RAD = 6%), and TR (ICC = 0.99, RAD = 1%).

Conclusions

STGD1's complex morphology made outer retina segmentation challenging. Measurements of the inner ring, including the intact area of IS (i.e., the ellipsoid zone [EZ]) and ONL and TR thicknesses, had good reproducibility and showed anatomical impairment.

Translational Relevance

ONL and TR thicknesses and the EZ intact area in the ETDRS inner ring hold potential as structural endpoints for STGD1 trials. Structure-function relationships need to be further established.

Stereotactic radiotherapy for wet age-related macular degeneration (INTREPID): influence of baseline characteristics on clinical response

PURPOSE

To determine which patients respond best to stereotactic radiotherapy (SRT) for neovascular age-related macular degeneration.

METHODS

Participants (n = 230) receiving intravitreal anti-vascular endothelial growth factor injections for neovascular age-related macular degeneration enrolled in a randomized, double-masked sham-controlled trial comparing 16 Gray, 24 Gray, or Sham SRT. In a post hoc analysis, participants were grouped according to their baseline characteristics, to determine if these influenced SRT efficacy.

RESULTS

At 52 weeks, SRT was most effective for lesions ≤4 mm in greatest linear dimension and with a macular volume greater than the median value of 7.4 mm. For 26% of the participants with both these characteristics, SRT resulted in 55% fewer ranibizumab injections (2.08 vs. 4.60; P = 0.0002), a mean visual acuity change that was 5.33 letters superior to sham (+2.18 vs. -3.15 letters; P = 0.0284), and a 71.1-μm greater reduction in mean central subfield thickness (-122.6 vs. -51.5 μm; P = 0.027). Other features associated with a positive response to SRT included pigment epithelial detachment and the absence of fibrosis.

CONCLUSION

Stereotactic radiotherapy is most effective for neovascular age-related macular degeneration lesions that are actively leaking at the time of treatment, and no larger than the 4-mm treatment zone.

Diabetic macular oedema quantified with spectral-domain optical coherence tomography--evaluation of boundary line artefacts and the effect on retinal thickness

PURPOSE

To characterize frequency, morphological cause and time-dependent change of boundary line artefacts in optical coherence tomography (OCT) examinations of centre-involved diabetic macular oedema (ciDME) patients who underwent ranibizumab treatment with 1-year follow-up and to evaluate the impact of artefacts on retinal thickness.

METHODS

One hundred and fourteen patients were examined with radial scan protocol by Topcon 3D OCT at baseline, 3 and 12 months. All B scans from all visits were examined for boundary line artefacts (artefacts) and were stratified by morphological element causing artefacts including hard exudates (HE), epiretinal membranes (ERM), optical opacities and serous detachments. Boundary line artefacts were manually corrected and the corrected central subfield thickness (CST) and macular volume were compared with automated values. Data were compared with a repeatability coefficient of 25 μm.

RESULTS

Boundary line artefacts were found in 51.8% of the total 342 OCT examinations and in 25.5% of the total 2052 B scans. Morphological elements that caused artefacts in the total 2052 B scans were HE (10.6%), ERM (10.3%), optical opacities (4.4%), serous detachments (1.7%) and others (1.2%). The number of artefacts due to HE decreased significantly (p = 0.0005), and the number of artefacts due to ERM were unchanged (p = 0.087) during 12 months. In OCT examinations with artefacts caused by HE, manually corrected CST was statistically significant higher than automated value at baseline and 3 months. For ERM, manually corrected CST was statistically significant lower than automated value at baseline and 12 months.

CONCLUSION

Boundary line artefacts in OCT examinations of ciDME patients using Topcon 3D OCT occur in 51.8%. In situation of boundary line artefacts in centre 1-mm area every fourth OCT examination has a change in CST beyond 25 μm.

Intravitreal Ranibizumab for neovascular Age-related macular degeneration in clinical practice: five-year treatment outcomes

BACKGROUND

Intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents are the established standard of care for neovascular age-related macular degeneration (nAMD). However, data on long-term outcomes of this therapy are limited. The purpose of this study was to assess the visual and anatomical outcomes and safety profile of intravitreal ranibizumab in treating nAMD over a period of five years.

METHODS

208 patients (208 eyes) were included in this retrospective case series study. Intervention was an "as-needed" treatment model. Visual acuity (VA), central macular thickness (CMT), ophthalmic examination, and adverse events (AEs) were assessed in each visit. Snellen VA was converted to Early Treatment Diabetic Retinopathy Study letters for analysis.

RESULTS

The average VA improved by 1.9 letters after one year (p = 0.017), and decreased by 2.4 letters over five years of treatment (p = 0.043). At the end of year five, 11.1 % of patients (23/208) had improved VA by more than 15 letters and 68.8 % (143/208) had VA improvement or loss less than or equal to 15 letters, while 20.2 % of patients (42/208) had a loss of more than 15 letters. Patients with VA of less than 35 letters at baseline showed significant VA improvement after five years of treatment. There was a positive relationship between injection numbers and VA improvement over the five-year period, after adjusting for age and baseline VA (p < 0.0005). Mean CMT decreased by 28.3 μm (p < 0.0005) over five years. Ocular AEs, serious adverse events (SAEs), and systemic SAEs occurred in 4.6 %, 0.48 %, and 2 % of patients, respectively, during the follow-up period.

CONCLUSIONS

The use of intravitreal ranibizumab in an as-needed treatment regimen over a five-year period was effective in maintaining vision in patients with nAMD and in reducing macular thickness, with a relatively low rate of adverse and serious adverse events.

Parallelism as a novel marker for structural integrity of retinal layers in optical coherence tomographic images in eyes with epiretinal membrane

PURPOSE

To propose a new parameter, "Parallelism," to evaluate retinal layer integrity on spectral-domain optical coherence tomography (SDOCT), and to investigate the association between parallelism and visual function in eyes with idiopathic epiretinal membrane (ERM).

DESIGN

Retrospective, observational evaluation of a diagnostic test.

METHODS

We evaluated a consecutive series of 57 eyes of 57 patients with ERM and 30 healthy eyes of 30 volunteers for whom M-CHARTS testing and SDOCT were performed on the same day. OCT images were skeletonized, and the orientation of segmented lines in the image was termed "Parallelism" and was expressed as a value ranging from 0-1 and increasing as the retinal layers ran more parallel with each other. The relationships between parallelism and visual acuity and between parallelism and metamorphopsia score were evaluated.

RESULTS

In normal eyes, parallelism was nearly homogeneous and varied slightly with the location. Parallelism in eyes with ERM was significantly lower than that in normal eyes. In the horizontal and vertical scans, parallelism was significantly correlated with visual acuity, horizontal metamorphopsia score, and vertical metamorphopsia score. Parallelism of the center (1 mm) in the horizontal scan was strongly correlated with horizontal metamorphopsia score (R = -0.632; P < .0001). Significant negative correlation was found between parallelism and retinal thickness both in horizontal and vertical scans.

CONCLUSIONS

Parallelism was significantly lower in eyes with ERM than in normal eyes, and correlated strongly with metamorphopsia and visual acuity in eyes with ERM.

Identifying the boundaries of retinal pigment epithelial detachments using two spectral-domain optical coherence tomography instruments

BACKGROUND AND OBJECTIVE

To compare two spectral-domain optical coherence tomography (SD-OCT) instruments in identifying the boundaries of retinal pigment epithelium detachment (PED).

PATIENTS AND METHODS

27 eyes were scanned with Cirrus and Spectralis SD-OCT instruments during a single visit. Two Cirrus scan patterns were used: the 512 × 128 and 200 × 200 covering a 6 × 6 mm (20° × 20°) area. The Spectralis scan pattern consisted of seven B-scans, averaged 51 times, covering a 30° × 5° area. The main outcome measures were the retinal thickness at the foveal center and the number of segmentation failures on the central B-scan.

RESULTS

The Spectralis algorithm failed to follow the proper retinal contour in 25 eyes (92.6%), while the segmentation on the Cirrus instrument was successful in every central B-scan. Spectralis yielded greater retinal thickness measurements in all cases, and the average difference between Cirrus and Spectralis was 139 μm (P < .001). The intraclass correlation coefficient between the two Cirrus scan patterns was 0.998, and Cirrus versus Spectralis was 0.21.

CONCLUSIONS

The Cirrus SD-OCT instrument identifies the appropriate segmentation boundaries in the presence PED. The Spectralis SD-OCT algorithm was unreliable in segmenting PEDs, leading to inaccurate retinal thickness measurements unless manual adjustments were performed.

Reliability and reproducibility of spectral and time domain optical coherence tomography images before and after correction for patients with age-related macular degeneration

Purpose: To evaluate the reproducibility and reliability of optical coherence tomography scans obtained using the time domain (TD-OCT) Stratus ^TM OCT, and the Spectral Domain (SD-OCT) Spectralis ^TM and Cirrus ^TM OCT devices before and after manual correction in eyes with either Neovascular (NV-AMD) or Non-Neovascular (NNV-AMD) age-related macular degeneration.

Design: Prospective observational study.

Methods:

Setting: University-based retina practice.

Patients: Thirty-six patients (50 eyes) with NV-AMD or NNV-AMD.

Procedure: OCT scans were taken simultaneously using one TD-OCT and two SD-OCT devices.

Main Outcome Measures: Macular thickness measurements were assessed before and after correction of the algorithm by constructing Bland-Altman plots for agreement and calculating intraclass correlation coefficients (ICCs) and coefficients of repeatability (COR) to evaluate intraclass repeatability.

Results: Spectralis had the highest number of images needing manual correction.  All machines had high ICCs, with Spectralis having the highest.  Also, Bland-Altman plots indicated that there was low agreement between Cirrus™ and Stratus™, Spectralis™ and Stratus™, while there was good agreement between the Cirrus™ and Spectralis™.  The CORs were lowest for Spectralis ^TM and similar and higher for Cirrus ^TM and Stratus ^TM.  Agreement, CORs, and ICCs generally improved after manual correction, but only minimally. 

Conclusion: Agreement is low between devices, except between both SD-OCT machines.  Manual correction tends to improve results.