Scanning laser 'en face' retinal imaging of epiretinal membranes.

PURPOSE: Comparison of scanning laser ophthalmoscopy (SLO) based 'en face' imaging techniques of patients with epiretinal membranes (ERM) and evaluation of the accuracy of preoperative diagnostic imaging. METHODS: A consecutive, prospective series of 53 study eyes of 46 patients with clinically diagnosed and in optical coherence tomography (OCT) confirmed symptomatic ERMs were included in this study. Spectral domain (SD-) OCT volume scans (20° × 20° with 49 horizontal sections, ART 15) including SLO en face and fundus autofluorescence (FAF) images of the macula were obtained with HRA2 (Heidelberg Retina Angiograph-Optical Coherence Tomography, Heidelberg Engineering, Heidelberg, Germany). In addition, wide-field SLO color and FAF images (Optomap 200Tx, Optos PLC, Dunfermline, UK) were performed also covering the macular area. En face images of both devices were graded for each included study eye based on SD-OCT cross sectional scans. RESULTS: Grading of SD-OCT (HRA2) based SLO en face green-blue enhanced multi-color, green reflectance, blue reflectance and standard multi-color visualization revealed a better detectability of ERM than SD-OCT-based en face infrared or FAF images or wide-field SLO (Optomap) based pseudo-color, red laser separation, green laser separation, or FAF images. Both FAF visualizations, HRA2 and Optomap based, achieved low mean scores. SD-OCT based en face thickness map visualization revealed good visualization but poor demarcation of epiretinal membranes. CONCLUSIONS: In summary, en face regular or enhanced multicolor SLO images acquired with HRA2 allow a better visualization of epiretinal membranes for preoperative evaluation compared to SD-OCT based en face thickness map or pseudo-color images acquired with Optomap while infrared or FAF images are least suitable to depict epiretinal membranes.

Green-light fundus autofluorescence in diabetic macular edema.

AIM: To evaluate the role of central green-light fundus autofluorescence (FAF) in diabetic macular edema (DME). METHODS: A consecutive series of 92 study eyes with diabetic retinopathy were included. Out of those, 51 diabetic eyes had DME and were compared to 41 diabetic eyes without DME. In all subjects, green-light FAF images were obtained, quantified and classified into various FAF patterns. Cross-sectional optical coherence tomography (OCT) scans were obtained for evaluation of Inner/Outer segment (IS/OS) layer integrity, measurements of central RPE-IS/OS layer thickness as well as classification of DME into various subtypes. RESULTS: Mean central green-light FAF intensity of eyes with DME (1.289±0.140)log did not significantly differ from diabetic patients without DME (1.317±0.137)log. Most classifiable FAF patterns were seen in patients with cystoid DME. Mean central retinal thickness (CRT) of all study eyes with DME was (501.9±112.4)µm compared to (328.2±27.0)µm in diabetic patients without DME. Patients with DME had significantly more disrupted photoreceptor IS/OS layers than diabetic patients without DME (28/51 vs 5/41, P<0.001). Mean RPE-IS/OS thickness of patients with DME (60.7±14.1)µm was significantly (P<0.001) lower than in diabetic eyes without DME (73.5±9.4)µm. Correlation analys1s revealed non-significant correlations of green-light FAF intensity and OCT parameters in all subtypes of DME. CONCLUSION: Our results indicate a poor correlation of central green-light FAF intensity with CRT, IS/OS layer integrity or RPE-IS/OS layer thickness in diabetic patients with or without DME and its various subtypes. Thus, central green-light FAF is not suitable for detection of retinal thickening in DME.

Reproducibility of retinal thickness measurements in patients with age-related macular degeneration using 3D Fourier-domain optical coherence tomography (OCT) (Topcon 3D-OCT 1000).

PURPOSE: Conventional time-domain optical coherence tomography (OCT) has become an important tool for following dry or exudative age-related macular degeneration (AMD). Fourier-domain three-dimensional (3D) OCT was recently introduced. This study tested the reproducibility of 3D-OCT retinal thickness measurements in patients with dry and exudative AMD. METHODS: Ten eyes with dry AMD and 12 eyes with exudative AMD were included in the study. Sets of three OCT 6 × 6-mm raster scans were taken by one operator. Mean retinal thickness was calculated for 36 areas. Coefficients of variation (CoV) were calculated for each patient and area. For analysis, two separate areas (central and peripheral) were defined. Generalized estimating equations (GEEs) were applied to all 36 subfields in order to analyse possible differences in CoV and mean retinal thickness between dry and exudative AMD. RESULTS: Mean retinal thickness values were significantly larger in the central area in exudative AMD (p < 0.001). Mean CoV for exudative AMD was 3.7% (standard deviation [SD] 1.4%). Mean CoV for dry AMD was 1.8 (SD 0.6%). The reproducibility of retinal thickness measurements was significantly less in exudative AMD (p = 0.009). CONCLUSIONS: Reproducibility of 3D-OCT retinal thickness measurements was good in both groups. However, reproducibility was significantly better in dry AMD than in exudative AMD.

Comparison of three different optical coherence tomography models for total macular thickness measurements in healthy controls.

BACKGROUND/AIMS: Conventional time domain optical coherence tomography (OCT) has become an important diagnostic tool to measure retinal thickness in clinical routine. Recently, different models of high-speed, high-resolution frequency domain OCTs have been introduced by various manufacturers. The purpose of this study was to compare 3 commercially available OCT models for retinal thickness measurements in healthy controls. METHODS: OCT scans were performed on 28 healthy eyes with the RTVue-100 FD-OCT (Optovue Inc., USA), the Cirrus HD-OCT (Carl Zeiss Meditec Inc., USA) and the Stratus OCT 3000 (Carl Zeiss Meditec Inc.). Retinal thickness values were calculated and compared between OCT models. RESULTS: Differences in mean retinal thickness measurements between OCT models were statistically significant. Mean retinal thickness measurement with Cirrus OCT, RTVue OCT and with Stratus OCT was 300, 265 and 257 microm, respectively. CONCLUSION: Measurements with different OCT models lead to significantly different retinal thickness values.

Reproducibility of retinal thickness measurements in healthy subjects using spectralis optical coherence tomography.

PURPOSE: To test the reproducibility of retinal thickness measurements in healthy volunteers of a new Frequency-domain optical coherence tomography (OCT) device (Spectralis OCT; Heidelberg Engineering, Heidelberg, Germany). DESIGN: Prospective, observational study. METHODS: Forty-one eyes of 41 healthy subjects were included into the study. Intraobserver reproducibility was tested with 20 x 15 degree raster scans consisting of 37 high-resolution line scans that were repeated three times by one examiner (M.N.M.). Mean retinal thickness was calculated for nine areas corresponding to the Early Treatment Diabetic Retinopathy Study (ETDRS) areas. Coefficients of variation (COV) were calculated. RESULTS: Retinal thickness measurements were highly reproducible for all ETDRS areas. Mean total retinal thickness was 342 +/- 15 microm. Mean foveal thickness was 286 +/- 17 microm. COVs ranged from 0.38% to 0.86%. Lowest COV was found for the temporal outer ETDRS area (area 7; COV, 0.38%). Highest COV was found for the temporal inner ETDRS area (area 3; COV, 0.86%). Mean difference between measurement 1 and 2, measurement 1 and 3, and measurement 2 and 3 for all ETDRS areas was 1.01 microm, 0.98 microm, and 0.99 microm, respectively. CONCLUSION: Spectralis OCT retinal thickness measurements in healthy volunteers showed excellent intraobserver reproducibility with virtually identical results between retinal thickness measurements performed by one operator.

Reproducibility of nerve fiber layer thickness measurements using 3D fourier-domain OCT.

PURPOSE: Conventional time-domain optical coherence tomography (OCT) has been shown to provide reproducible retinal nerve fiber layer (RNFL) measurements. Recently, high-speed, high-resolution Fourier-domain 3D-OCT has been introduced to improve OCT quality. It can provide 6-mm(2) high-density scans to provide RNFL thickness measurements. The purpose of this study was to test the reproducibility of 3D-OCT RNFL thickness measurements in healthy volunteers. METHODS: Thirty-eight eyes were included in the study. High-density 6-mm(2) 3D scans were registered by two independent operators. RNFL thickness was calculated for eight areas corresponding to the ETDRS areas and for two ring areas. The ETDRS grid was centered on the optic disc. Intraclass correlation coefficients (ICC) and coefficients of variation (COV) were calculated. Interobserver reproducibility was visualized by using Bland-Altman analysis. RESULTS: Intrasession reproducibility was good with a mean ICC of 0.90. The mean COV for operator 1 and 2 was 4.2% and 4%, respectively (range, 1.9%-6.7%). Highest reproducibility was found for the two ring areas and the superior and inferior quadrants. Mean differences in RNFL thickness measurements for ring 1 and 2 between operator 1 and 2 were 0.9 microm (limits of agreement, -11.4 to +9.6 microm) and 0.1 microm (limits of agreement -4.1 to +3.9 microm), respectively. CONCLUSIONS: 3D-OCT RNFL thickness measurements in healthy volunteers showed good intra- and interobserver reproducibility. 3D-OCT provides more RNFL thickness information compared to conventional time-domain OCT measurements and may be useful for the management of glaucoma and other optic neuropathies.