Central retinal thickness measured with HD-OCT shows a weak correlation with visual acuity in eyes with CSME. Retinal thickness in diabetic retinopathy: comparison of optical coherence tomography, the retinal thickness analyzer, and fundus photography. Comparison of time-domain OCT and fundus photographic assessments of retinal thickening in eyes with diabetic macular edema. Automated detection of clinically significant macular edema by grid scanning optical coherence tomography. Comparison of the clinical diagnosis of diabetic macular edema with diagnosis by optical coherence tomography. Diabetic macular edema assessed with optical coherence tomography and stereo fundus photography. Topography of diabetic macular edema with optical coherence tomography. Detection of diabetic foveal edema: contact lens biomicroscopy compared with optical coherence tomography.
To investigate the correlation between increased retinal thickness (RT) measured with spectral domain high-definition optical coherence tomography (OCT) (Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, California, USA)) and best-corrected visual acuity (BCVA) in eyes with clinically significant macular oedema (CSME) and type 2 diabetes.
                Seventy eyes with CSME were included in this observational study. Sixty-two eyes were considered for analysis and were classified as having/not having retinal thickening in the central fovea (central 500-microm-diameter circle) by Cirrus HD-OCT. RT measurements were computed and correlated with BCVA. For comparison purposes, the Stratus OCT (Carl Zeiss Meditec, Dublin, California, USA) central point thickness was also obtained in these eyes.
                In the 19 eyes with CMSE identified by Cirrus HD-OCT without increased RT in the central fovea (500-microm-diameter circle), no correlation was found between RT and BCVA (R=0.062; 95% CI -0.404 to 0.502). In the 43 eyes where the Cirrus HD-OCT identified an increased RT in the central fovea (central 500-microm-diameter circle), only a moderate correlation between RT and BCVA was found (R=-0.459; 95% CI -0.667 to -0.184).
                Correlations between RT and BCVA in CSME are only present when the central 500-microm-diameter circle is involved. However, even in this circumstance, a correlation was found in only 48.8% of the cases. RT cannot, therefore, be used as a surrogate outcome for visual acuity changes. Optical coherence tomography (OCT) and the retinal thickness analyzer (RTA) have proved their ability to measure retinal thickness in healthy subjects and diabetics reliably. In the present study, both techniques were compared for the same study population of diabetic patients, and the findings were related to macular edema shown by stereo fundus photography (SFP).
                Maculas of 124 eyes from 69 patients with diabetes mellitus were examined with OCT and the RTA. Measurements of retinal thickness were compared with signs of macular edema shown by SFP. For each eye, nine different sectors were analyzed (a foveal sector, four parafoveal sectors, and four extrafoveal sectors). Thirteen eyes with a normal macula served as controls. Sensitivity and specificity of detecting clinically significant macular edema (CSME) were calculated.
                Of 111 eyes, 64 showed signs of CSME by SFP. Mean retinal thickness +/- SD of the foveal sector was 249 +/- 104 microm by RTA and 295 +/- 124 microm by OCT measurements. There was a moderate overall correlation between OCT and the RTA (r = 0.66). The correlation was best in the foveal sector (r = 0.82). Overall correlation with SFP was better for OCT (r = 0.77) than for the RTA (r = 0.62). Sensitivity of detecting CSME was consistently higher with OCT, while the RTA showed higher specificity.
                Both measuring techniques yielded similar results when examining eyes of patients with diabetes, although absolute values differed. OCT seems to be more suitable in the clinical screening for macular edema due to its high sensitivity (>90%) with appropriate analysis parameters. The RTA is more prone to erroneous or missing thickness readings particularly under difficult measuring conditions. To explore the correlation between optical coherence tomography (OCT) and stereoscopic fundus photographs (FP) for the assessment of retinal thickening (RT) in diabetic macular edema (DME) within a clinical trial.
                OCT, FP, and best corrected visual acuity (VA) measurements were obtained in both eyes of 263 participants in a trial comparing two photocoagulation techniques for DME. Correlation coefficients (r) were calculated comparing RT measured by OCT, RT estimated from FP, and VA. Principal variables were central subfield retinal thickness (CSRT) obtained from the OCT fast macular map and DME severity assessed by a reading center using a seven-step photographic scale combining the area of thickened retina within 1 disc diameter of the foveal center and thickening at the center.
                Medians (quartiles) for retinal thickness within the center subfield by OCT at baseline increased from 236 (214, 264) microm in the lowest level of the photographic scale to 517 (455, 598) microm in the highest level (r = 0.67). However, CSRT interquartile ranges were broad and overlapping between FP scale levels, and there were many outliers. Correlations between either modality and VA were weaker (r = 0.57 for CSRT, and r = 0.47 for the FP scale). OCT appeared to be more reproducible and more sensitive to change in RT between baseline and 1 year than was FP.
                There was a moderate correlation between OCT and FP assessments of RT in patients with DME and slightly less correlation of either measure with VA. OCT and FP provide complementary information but neither is a reliable surrogate for VA. To compare the detection of clinically significant diabetic macular edema (DME) by an optical coherence tomography (OCT) grid scanning protocol and biomicroscopic examination.
                Retrospective case series.
                Outpatients at the Doheny Eye Institute.
                The clinical and imaging records of a consecutive series of 71 eyes of 40 patients referred for DME who underwent OCT using the both the Macular Grid 5 (MG5) scanning protocol (to allow a more evenly distributed sampling of points in the macula) and the standard Fast Macular Thickness Map (FMTM) pattern were reviewed. An automated algorithm was developed to generate a retinal thickness map using the MG5 data, which was then compared with a normative database to identify presumed areas of retinal edema. Clinically significant macular edema (CSME) was also identified by clinical examination and stereoscopic fundus photographs for comparison with the results of the OCT protocols.
                Sensitivity and specificity of scanning protocols.
                Optical coherence tomograms were inspected visually, and automatically detected retinal boundaries were found to be correct in 69 of 71 MG5 scans and in 65 of 71 FMTM scans. Macular Grid 5 scanning was performed twice in each eye, and the repeatability (pooled standard deviation) of the total area of edema was 0.48 mm2 (coefficient of variation, 6.8%). Sensitivity and specificity of the MG5 for detection of CSME relative to the clinical examination were 89% and 86%, respectively, with kappa being 0.74. Macular Grid 5 and FMTM assessment of foveal CSME also showed good agreement, with kappa being 0.68.
                The analysis algorithm for the OCT MG5 grid scan seems to be accurate and repeatable. Automated detection of CSME by the MG5 analysis correlated well with the clinical grading and standard OCT analysis (FMTM). Macular Grid 5 provides more information regarding the perifoveal macula than FMTM and may be of value to clinicians in planning treatment and in future studies of macular edema. To compare the diagnosis of diabetic macular edema (DME) by stereoscopic slit-lamp biomicroscopic examination of the fundus with a 78-diopter noncontact lens with diagnosis by optical coherence tomography (OCT).
                Prospective, double-masked, noninterventional diagnostic study.
                Analysis of slit-lamp biomicroscopic findings compared with OCT measurements.
                Patients with DME from a private retina practice.
                Presence or absence of macular thickening.
                The reference range for this clinic was comparable to reference ranges published from other clinics. The clinical detection of DME was less than detection by OCT. Chance-corrected agreements (kappa statistic) of the 2 methods were 0.63 for the foveal zone and 0.36 to 0.42 for the 4 parafoveal zones. The errors committed in clinical examination were primarily of the type in which clinical examination did not detect DME but OCT did (58%-90%) for the 5 zones analyzed.
                Reference ranges for OCT seem to be similar for different clinical settings, suggesting the usefulness of OCT in multicenter studies. The current standard of care for DME detection, stereoscopic slit-lamp examination of the fundus, is less sensitive than OCT for detection of DME. Because the principal therapy for DME, focal laser photocoagulation, is mainly sight preserving and not sight restoring, the wider use of OCT may beneficially impact visual disability from DME. To compare retinal thickening in diabetic macular edema assessed subjectively by evaluation of stereo fundus photographs with that assessed objectively by optical coherence tomography (OCT).
                Forty-degree stereo fundus photographs of the macular field and OCT scans in 84 eyes of 47 patients with diabetes were compared in terms of both location and area of retinal thickening. Six radiating 6-mm OCT scans at intervals of 30 degrees were obtained, and the retinal thickness was compared with the mean retinal thickness +/- 2 SD of healthy control subjects (33 eyes). Subsequently, retinal thickness was mapped topographically and the subjectively assessed retinal thickening map was overlaid. The degree of agreement on location was evaluated as retinal thickening present or absent in nine subfields of the fundus. Area of retinal thickening was divided into four categories: no retinal thickening, less than 1 disc area (DA), less than 2 DAs, or less than 3 DAs, expressed as the kappa statistic.
                Exact agreement on location was found in 676 of 756 (84 x 9) observations (89.4%; kappa = 0.69; 95% confidence interval [CI]: 0.63-0.75). Two eyes in which both methods assessed the same amount of retinal thickening showed no agreement on location. These eyes were compared only in terms of location. Exact agreement on area was found in 69 (84.1%) of 82 eyes. Weighted kappa (kappa(w)) = 0.79; 95% CI: 0.76-0.82).
                The degree of agreement between subjectively and objectively assessed retinal thickening was very good, implying that changes in diabetic macular edema can be accurately and prospectively measured with OCT. This study aimed to develop a protocol to screen and monitor patients with diabetic macular thickening using optical coherence tomography (OCT), a technique for high-resolution cross-sectional imaging of the retina.
                A cross-sectional pilot study was conducted.
                A total of 182 eyes of 107 patients with diabetic retinopathy, 55 eyes from 31 patients with diabetes but no ophthalmoscopic evidence of retinopathy, and 73 eyes from 41 healthy volunteers were studied.
                Six optical coherence tomograms were obtained in a radial spoke pattern centered on the fovea. Retinal thickness was computed automatically from each tomogram at a total of 600 locations throughout the macula. Macular thickness was displayed geographically as a false-color topographic map and was reported numerically as averages in each of nine regions.
                Correlation of OCT with slit-lamp biomicroscopy, fluorescein angiography, and visual acuity was measured.
                Optical coherence tomography was able to quantify the development and resolution of both foveal and extrafoveal macular thickening. The mean +/- standard deviation foveal thickness was 174 +/- 18 microns in normal eyes, 179 +/- 17 microns in diabetic eyes without retinopathy, and 256 +/- 114 microns in eyes with nonproliferative diabetic retinopathy. Foveal thickness was highly correlated among left and right eyes of normal eyes (mean +/- standard deviation difference of 6 +/- 9 microns). Foveal thickness measured by OCT correlated with visual acuity (r2 = 0.79). A single diabetic eye with no slit-lamp evidence of retinopathy showed abnormal foveal thickening on OCT.
                Optical coherence tomography was a useful technique for quantifying macular thickness in patients with diabetic macular edema. The topographic mapping protocol provided geographic information on macular thickness that was intuitive and objective. To compare contact lens biomicroscopy with optical coherence tomography (OCT) for the detection of diabetic foveal edema.
                Study participants consisted of a convenient cohort of consecutive patients with diabetes mellitus seen at the Wilmer Eye Institute's Retinal Vascular Center, Baltimore, MD. Case characteristics were recorded and eyes were examined by 1 of 4 retina specialists by means of contact lens biomicroscopy. Edema involving the center of the macula was assessed as definitely present, questionably present, or definitely not present. The OCT testing was performed and interpreted by trained technicians, masked to the physicians' assessment of foveal edema. Agreement between OCT and contact lens examination for the absence or presence of foveal edema was evaluated.
                One hundred seventy-two eyes of 95 patients with diabetes were enrolled in August and September 2002. Foveal thickness was objectively measured by OCT in 170 (99%) of 172 cases. We found excellent agreement between OCT and contact lens examination for the absence or presence of foveal edema when OCT thickness was normal (<or=200 microm) or moderately to severely increased (>300 microm). However, agreement was poor when foveal thickness was mildly increased on OCT (201-300 microm).
                Agreement between contact lens examination and OCT for the detection of diabetic foveal edema is poor when OCT thickening is mild. This suggests that contact lens biomicroscopy is relatively insensitive for the detection of mild foveal thickening apparent on OCT. Additional studies are needed to investigate the natural course of cases with mildly increased foveal thickness on OCT that do not appear thickened clinically.
Central retinal thickness measured with OCT cannot be used as a stand-alone test to diagnose the central type of CSMO and decide on the use of laser photocoagulation in patients who are referred to retina clinics. In fact, there is a substantial disagreement of OCT with the ETDRS definition of CSMO based on clinical examination. Some researchers have observed that OCT can detect macular thickening earlier than clinical examination, but also found that such cases did not necessarily progress to CSMO and need photocoagulation.
Care should be taken in applying the conclusions of this review to other test-treatment pathways. In fact, OCT will become an essential tool to manage antiangiogenic therapy, an expanding therapeutic option for patients with macular oedema due to DR, because OCT is a component of the diagnostic algorithms of studies on this new treatment.