Quantitative assessment of retinal thickness in diabetic patients with and without clinically significant macular edema using optical coherence tomography

PURPOSE: To assess patients with diabetic macular edema quantitatively using optical coherence tomography (OCT). METHODS: OCT was performed in 14 eyes with diabetic retinopathy and ophthalmoscopic evidence of clinically significant macular edema (CSME) and in 19 diabetic eyes without CSME. Retinal thickness was computed from the tomograms at fovea and other 36 locations throughout the macula. RESULTS: The mean +/- standard deviation foveal thickness was 255.6 +/- 138.9 microm in eyes with CSME, and 174.6 +/- 38.2 microm in eyes without CSME (p = 0.051). Within 2000 microm of the center of the macula, eyes with CSME had significantly thicker retina in the inferior quadrant than those without CSME (p < 0.01). The foveal thickness was correlated with logMAR visual acuity (gamma = 0.68, p < 0.01). OCT identified sponge-like retinal swelling and/or cystoid macular edema in 11 (58%) eyes without CSME, and in 12 (86%) eyes with CSME. CONCLUSIONS: Criteria of CSME seem to be insufficient in really identifying macular edema. OCT may be more sensitive than a clinical examination in assessing diabetic macular edema and is a quantitative tool for documenting changes in macular thickening.     

Retinal thickness study with optical coherence tomography in patients with diabetes

PURPOSE: To quantitatively assess retinal thickness by optical coherence tomography (OCT) in normal subjects and patients with diabetes. This study was intended to determine which retinal thickness value measured with OCT best discriminates between diabetic eyes, with and without macular edema. METHODS: OCT retinal thickness was measured by a manual technique in a total of 26 healthy volunteers (44 control eyes) and 85 patients with diabetes (148 eyes) with the clinical diagnosis of no diabetic retinopathy (45 eyes), nonproliferative diabetic retinopathy without clinically significant macular edema (CSME; 54 eyes), proliferative diabetic retinopathy without CSME (21 eyes), and 28 eyes with diabetic retinopathy with CSME. Independent predictors of the presence of CSME were quantified by using univariate and multivariate logistic regression analyses. Receiver operating characteristic (ROC) curves were generated to evaluate and compare the predictor variables. The correlation of retinal thickness measurements and visual acuity was calculated. RESULTS: There were statistically significant differences in foveal thickness between control eyes and all the other eye groups (P = 0.001). Diabetic eyes with CSME had a statistically significant greater thickness in each of the areas compared with the other groups. In a multivariate logistic regression model, foveal thickness was a strong and independent predictor of CSME (odds ratio [OR], 1.037; 95% confidence interval [CI] 1.02-1.05). The area under the ROC curve of this predictor variable was 0.94 (P = 0.001). For a cutoff point of 180 microm, the sensitivity was 93%, and specificity was 75%. Foveal thickness correlated with visual acuity in a log minimum angle of resolution (logMAR) scale (Spearman's rho = 0.9, P = 0.001). CONCLUSIONS: These results suggest that foveal thickening over 180 microm measured by OCT may be useful for the early detection of macular thickening and may be an indicator for a closer follow-up of the patient with diabetes.     

Comparison of foveal thickness measured with the retinal thickness analyzer and optical coherence tomography.

PURPOSE: To assess and compare the reliability and reproducibility of retinal thickness measurements for the retinal thickness analyzer (RTA) and optical coherence tomography (OCT) in normal and edematous retina. METHODS: The authors measured the foveal thickness of 21 normal eyes and 9 eyes with macular edema with both methods in random order. With the RTA, the fovea was measured 10 times; with the OCT, six scans (one horizontal and five vertical cross-sections) of the fovea were obtained. RESULTS: Mean foveal thickness of normal eyes measured 153 microm with OCT and 181 microm with RTA (median for both methods 150 microm). Coefficients of variation (CV) within the same subjects were 10% (OCT) and 9% (RTA) reducing to 9% (OCT) and 7% (RTA) when scans were repeated only five times for both methods. The RTA, however, yielded an interpatient CV of 33% (OCT 17%), which was caused by several falsely high readings in normal individuals. In eyes with retinal thickening the OCT measured a mean of 324 microm with 15% intra- and 58% interpatient CV. The RTA yielded a mean of 403 microm with CV of 18% and 73%, respectively. CONCLUSION: Both methods yield reproducible measurements of foveal thickness in normal individuals and individuals with macular edema. However, falsely high measurements may occur with the RTA, reducing its reliability as compared to the OCT.     

Diurnal variation in clinically significant diabetic macular edema measured by the Stratus OCT

PURPOSE: To investigate diurnal variation in clinically significant macular edema (CSME) using the Stratus OCT (Carl Zeiss Meditec). METHODS: Fifteen eyes of 15 diabetic patients with CSME and 10 healthy subjects (controls) underwent four optical coherence tomography (OCT) measurements of macular thickness with the fast macular thickness mapping protocol of the Stratus OCT at 9 am, 12 pm, 3 pm, and 6 pm. Early Treatment Diabetic Retinopathy Study visual acuity and refraction data were also collected at each time. Retinal thickness measurements from each of the nine macular Early Treatment Diabetic Retinopathy Study areas of the retina map, visual acuity, and refraction were plotted over time. RESULTS: Mean retinal thickness remained unchanged in all retinal sectors over the course of the day for the controls and the 6 diabetic patients with a baseline foveal thickness of <300 mum, and it significantly decreased in 7 of the 9 retinal sectors for the 9 diabetic patients with a baseline foveal thickness of > or =300 microm (ANOVA model for repeated measures). In these patients, the mean initial foveal thickening +/- SD of 211 +/- 104 microm was reduced by an average of 6.1%, 15.2%, and 21.2% at 12 pm, 3 pm, and 6 pm, respectively. Two of these nine patients also had an increase in visual acuity without change in refraction. There were no changes in refractive errors over the course of the study in the two groups. A positive correlation between initial central thickening and decrease in thickness was found (r = 0.732; P = 0.002). CONCLUSION: This study suggests that macular thickening, as measured by the Stratus OCT, may spontaneously decrease in some patients with more severe CSME over the course of the day, and it confirms previous findings. However, in our study, the entity of this decline was relatively small and not relevant from a clinical standpoint.     

Comparison between retinal thickness analyzer and optical coherence tomography for assessment of foveal thickness in eyes with macular disease

PURPOSE: To use the retinal thickness analyzer (RTA) and optical coherence tomography (OCT) scanners for quantitative measurement of retinal thickness in eyes with macular disease. DESIGN: In a cross-sectional study, 44 patients (55 eyes) with macular disease and sufficient media clarity to visualize the fundus using clinical biomicroscopy underwent an ophthalmologic examination, fluorescein angiography, RTA, and OCT during the same visit. METHODS: Foveal and foveal center (foveolar) retinal thickness measurements were obtained by RTA and by OCT. RESULTS: Retinal thickness measurements were obtained by OCT in all 55 eyes and by RTA in 34 eyes (62%, primarily due to interference from media opacities). In the 34 eyes in which measurements were obtained by both instruments, mean foveal thickness was 291 and 269 microm for OCT and RTA, respectively; foveolar thickness was 277 and 265 microm, respectively. OCT and RTA measurements of foveal thickness were strongly correlated (intraclass correlation coefficient = 0.89), as were measurements of the foveolar thickness (intraclass correlation coefficient = 0.94). Topographic maps generated by the two techniques yielded qualitatively similar information. CONCLUSIONS: Overall, there was excellent agreement between RTA and OCT measurements. Each technique has advantages that may make its use preferable in a particular subgroup of eyes or to describe a particular disease process. An important consideration is that media opacities create less interference for OCT than for RTA, so that in study populations with a moderate-to-high prevalence of media opacity, images can be obtained in a greater percentage of eyes by OCT than by RTA.     

Retinal thickness measurements with optical coherence tomography and the scanning retinal thickness analyzer

PURPOSE: To assess the reproducibility of retinal thickness measurements in normal subjects and to compare foveal thickness using optical coherence tomography (OCT) and the scanning retinal thickness analyzer (RTA). METHODS: Two examiners performed foveal thickness measurements in 24 eyes of 12 healthy subjects using both OCT and the scanning RTA. Intraclass correlation coefficients (ICC) (intra-examiner and inter-examiner) were calculated for the paired foveal thickness measurements obtained with each instrument. RESULTS: The average foveal thicknesses measured with OCT and the scanning RTA were 155.1 +/- 14.9 microm and 107.8 +/- 18.6 microm, respectively. The intra-examiner ICCs from the two sessions using the OCT and the scanning RTA were 0.99 and 0.78 and 0.89 and 0.99, respectively. The inter-examiner ICCs of the OCT and the scanning RTA were 0.99 and 0.99, respectively. There was a significant correlation between the foveal thickness measurements with these two instruments (R2 = 0.629, P < 0.0001). CONCLUSION: The foveal thicknesses measured using OCT and the scanning RTA in healthy subjects agreed with the previously reported data on foveal thickness. Both instruments can reproducibly quantitate foveal thickness.     

Can optical coherence tomography predict the outcome of laser photocoagulation for diabetic macular edema?

BACKGROUND AND OBJECTIVE: To assess the outcome of laser photocoagulation in patients with diabetic macular edema. PATIENTS AND METHODS: Forty-seven patients (51 eyes) with clinically significant macular edema (CSME) undergoing grid laser photocoagulation were included. Clinical examination and optical coherence tomography (OCT) were performed at baseline and 3 to 4 months after treatment. The central foveal thickness, mean inner macular thickness (average retinal thickness in fovea and inner macular circle), and mean macular thickness were calculated. Based on the greatest OCT thickness at baseline, patients were grouped according to mild (< 300 microm; Group 1), moderate (300 to 399 microm; Group 2), and severe (> or = 400 microm; Group 3) macular edema. RESULTS: Group 2 showed significant reductions in central foveal thickness (23 microm, P = .02), mean inner macular thickness (18 microm, P = .02), and mean macular thickness (9 microm, P = .04) with slight improvement in visual acuity. Groups 1 and 3 did not show any significant change in macular thickness values and there was a statistically insignificant worsening of visual acuity in these groups. CONCLUSIONS: Patients with moderate macular thickening of 300 to 400 microm benefit most from laser treatment. OCT may help in choosing the appropriate treatment for CSME based on the degree of macular thickening. Long-term studies are warranted to confirm these findings.     

Precision and reliability of retinal thickness measurements in foveal and extrafoveal areas of healthy and diabetic eyes

PURPOSE: To determine the precision and reliability of retinal thickness measurements with an optical coherence tomograph (Stratus OCT 3; Carl Zeiss Meditec, Dublin, CA) and a retinal thickness analyzer (RTA; Talia Technology Ltd., Neve-Ilan, Israel) in foveal, parafoveal, and perifoveal areas. METHODS: Three measurements of all areas were performed within 1 hour on the same day with each instrument in the eyes of healthy volunteers and diabetic patients. The latter group was divided into eyes with and without macular edema. RESULTS: Measurement precision, expressed as the 95% limits of agreement (LA 95%), was significantly higher (i.e., a lower LA 95%, P < 0.01) for the OCT in comparison to the RTA in virtually all areas of the retina. Moreover, measurement reliability, expressed as the intraclass correlation coefficient, was high with the OCT (>0.90) and moderate to low with the RTA (0.26-0.89). A direct influence of macular edema itself on measurement precision of para- and perifoveal areas was found in the OCT measurements. CONCLUSIONS: The high measurement precision and reliability of the OCT suggests that this instrument is currently the most suitable technique for detection and follow-up of diabetic macular edema. When macular edema is present, the OCT can reliably detect changes of at least 36 microm at the fovea, 55 microm in parafoveal areas below a thickness of 744 microm, and 42 microm in perifoveal areas below a thickness of 1011 microm.     

Macular thickness in patients with choroidal neovascularization determined by RTA and OCT3: comparative results

AIMS: The authors conducted a study to compare retinal thickness in patients with choroidal neovascularization (CNV) using optical coherence tomography (OCT) and retinal thickness analyser (RTA). METHODS: In all, 11 eyes from 11 patients with subfoveal choroidal neovascularization were examined with OCT and RTA. RESULTS: Three patients could not be explored by RTA due to lack of fixation and high myopia. The mean foveal thickness was 289.9+/-92.1 microm with OCT and 207.7+/-60.8 microm with RTA. The mean perifoveal thickness was 293.8+/-46.3 microm and 200.8+/-61.3 microm, respectively. The maximal perifoveal thickness measured by OCT was 335+/-104.0 microm and 316+/-86.8 microm by RTA. CONCLUSION: OCT and RTA are able to detect increases in retinal thickness due to the presence of CNV and of fluid extravasation. They can be used in measuring retinal thickness in patients with CNV, although measures are not comparable between both systems.     

Quantitative analysis of diabetic macular edema after scatter laser photocoagulation with the scanning retinal thickness analyzer

PURPOSE: To define the effect of scatter laser photocoagulation on foveal retinal thickness. METHODS: A commercial scanning retinal thickness analyzer was used to measure retinal thickness. The foveal retinal thickness was measured at the central area of the fundus (0.4 x 0.4 mm). The method was applied to 20 consecutive patients (mean age, 52.4 +/-16.9 years) with diabetic retinopathy. Measurements were performed before and 6 weeks after scatter photocoagulation. Patients were examined by fluorescein angiography and slit-lamp biomicroscopy to detect macular edema. RESULTS: Mean foveal thickness before scatter photocoagulation was 187+/-45 microm, increasing to 221+/-46 microm after the treatment (P = 0.0001). The foveal thickness increased in 12 eyes (60%). Laser treatment increased macular permeability in two eyes (10%). Biomicroscopic examination revealed central macular thickening in one eye (5%). Visual acuity was reduced in four eyes (20%). CONCLUSIONS: Our results suggest that subclinical macular edema occurs after scatter laser photocoagulation. The retinal thickness analyzer is a sensitive tool for early detection of macular edema after laser treatment, because increases in retinal thickness as small as 34 microm cannot be assessed by slit-lamp biomicroscopy.     

Retinal thickness in diabetic retinopathy: a study using optical coherence tomography (OCT)

BACKGROUND AND OBJECTIVE: The authors conducted a controlled study to quantify macular retinal thickness in diabetic retinopathy using optical coherence tomography (OCT) as an objective and noninvasive tool. The relationship between retinal thickness and standard methods of evaluating macular edema was investigated. PATIENTS AND METHODS: A total of 136 patients in different stages of diabetic retinopathy were examined with OCT. In addition, fluorescein angiograms as well as standard eye examinations were conducted. The control group consisted of 30 individuals with a normal macula. RESULTS: In the controls, retinal thickness was 153 +/- 15 microm in the fovea, 249 +/- 19 microm in the temporal parafoveal region, and 268 +/- 20 microm in the nasal parafoveal region. In diabetic patients, retinal thickness was increased to 307 +/- 136 microm in the fovea, 337 +/- 88 microm in the temporal retina, and 353 +/- 95 microm in the nasal retina, respectively. The differences between diabetics and controls were highly significant (P < 0.001). Retinal thickening correlated with fluorescein leakage in the angiograms to some extent. There was an intermediate correlation between retinal thickness and visual acuity, particularly in patients without macular ischemia. Sensitivity of detecting clinically significant macular edema by measuring foveal retinal thickness was 89% and specificity was 96%. CONCLUSION: Optical coherence tomography allows us to quantify retinal thickness in diabetic retinopathy with excellent reproducibility. OCT is able to detect sight-threatening macular edema with great reliability.     

Diabetic macular edema: correlation between microperimetry and optical coherence tomography findings

PURPOSE: To compare the changes in macular sensitivity (microperimetry) and macular thickness with different degrees of diabetic macular edema. METHODS: Sixty-one eyes of 32 consecutive diabetic patients were included in this cross-sectional study. All included eyes underwent functional and morphologic examination of the macular area. Best corrected visual acuity (ETDRS charts), macular sensitivity, and macular thickness were quantified. Lesion-related macular sensitivity and retinal fixation were investigated with an advanced, automatic microperimeter. Optical coherence tomography (OCT) was used to quantify macular thickness. RESULTS: The 61 included eyes were graded, by two retinal specialists, for diabetic macular edema as follows: 16 were graded as no macular edema (NE), 30 as non-clinically significant macular edema (NCSME), and 15 as clinically significant macular edema (CSME). Macular thickness significantly increased from the NE to the CSME group (P<0.0001), whereas macular sensitivity significantly decreased from the NE to the CSME group (P<0.0021). A significant correlation coefficient was noted between retinal sensitivity and normalized macular thickness (r=-0.37, P<0.0001). Linear regression analysis showed a decrease of 0.83 dB (P<0.0001) for every 10% of deviation of retinal thickness from normal values. Visual acuity and central macular sensitivity correlated significantly in the NCSME group (r=-0.6, P=0.0008), but not in the NE (r=-0.144, P=0.6) or in the CSME (r=-0.46, P=0.11) groups. CONCLUSIONS: Macular edema may be better documented by adding macular sensitivity mapping by microperimetry to macular thickness measurement by OCT and visual acuity determination because macular sensitivity seems to be a relevant explanatory variable of visual function, independent of macular thickness data. Moreover, microperimetry may be of value in predicting the outcome of diabetic macular edema, because it incorporates a functional measure that may supplement the predictive value of OCT and visual acuity.     

Macular thickness measured by optical coherence tomography (OCT) in diabetic patients

PURPOSE: 1) To compare macular thickness (MT) by optical coherence tomography (OCT) in diabetics and controls; 2) to assess the relationship between MT and stage of diabetic retinopathy (DR) and macular edema (ME); 3) to quantify MT changes after laser treatment for ME. METHODS: One-hundred and thirty-seven patients with diabetes mellitus (216 eyes) were admitted to the study and examined by stereo-color fundus photos, retinal fluorangiography and OCT. DR was classified as: 1) no DR (46 eyes: 21.3%); 2) background DR (66 eyes: 30.6%); 3) pre-proliferative DR (50 eyes: 23.1%); 4) proliferative DR (54 eyes: 25%). The study group was then divided into three ME groups: 1) no edema (65 eyes: 30.1%); 2) not clinically significant ME (no CSME) (45 eyes: 20.8%); 3) clinically significant macular edema (CSME) (106 eyes: 49.1%). Three-month follow-up tomograms were taken to evaluate eyes laser-treated only for ME. The control group consisted of 50 eyes of 50 non-diabetic, age- and sex-matched subjects. RESULTS: MT was 369.3 +/- 163.2 microm in diabetics and 161.9 +/- 12.9 microm in controls (p < 0.001). In the four DR groups it was: 1) 211.0 +/- 37.6 microm; 2) 370.8 +/- 159.6 microm; 3) 419.1 +/- 138.2 microm; 4) 456.1 +/- 162.0 microm (p<0.001). In the three ME groups, MT was: 1)227.8 +/- 53.4 microm; 2) 321.8 +/- 124.2 microm; 3) 476.2 +/-146.6 microm (p < 0.001). In the 52 eyes treated with laser photocoagulation of the posterior pole only and with a follow-up > 3 months, MT before and after treatment was 468.2 +/- 83. 17 microm and 372.1 +/- 120.63 microm. CONCLUSIONS: MT was greater in diabetics than controls and tended to increase with DR and ME severity. OCT is a sensitive technique for detecting early diabetic macular abnormalities and quantifying their reduction after laser treatment.     

Early postoperative retinal thickness changes and complications after vitrectomy for diabetic macular edema

PURPOSE: To determine the early postoperative changes in retinal thickness and complications after pars plana vitrectomy for diabetic macular edema. DESIGN: Consecutive interventional case series. METHODS: Studied retrospectively, pars plana vitrectomy was performed on 65 consecutive eyes of 63 patients with diabetic macular edema. The follow-up interval ranged from 6 to 36 months (12.6 +/- 7.4 months [mean +/- standard deviation (SD)]). The indications of pars plana vitrectomy in this study were (1) diffuse diabetic macular edema, (2) preoperative visual acuity less than 20/40, and (3) noneffective macular photocoagulation therapy. Preoperative and postoperative examinations by stereoscopic biomicroscopy, color fundus photography of the macula and optical coherence tomography (OCT) were performed on all eyes. Preoperatively, direct photocoagulation to microaneurysms in the macula had been performed in 48 eyes, and focal/grid photocoagulation had been performed in five eyes. Preoperative examination showed that epiretinal membranes were observed in 20 eyes, cystoid macular edema in 40 eyes, and 23 eyes had a complete posterior vitreous detachment (PVD). Epimacular membranes, removed during surgery, were examined histopathologically. RESULTS: The postoperative mean best-corrected visual acuity (logarithm of the minimum angle of resolution [logMAR] = 0.696 +/- 0.491 [mean +/- SD]) was significantly better than the preoperative mean best-corrected visual acuity (0.827 +/- 0.361; P <.0001; Wilcoxon signed-rank test). The final visual acuity improved by 2 or more lines in 32 of 65 eyes (45%), remained unchanged in 32 of 65 eyes (49%), and exacerbated after the surgery in 4 of 65 eyes (6%) due to neovascular glaucoma (2 eyes) and residual cystoid macular edema (2 eyes). The postoperative foveal retinal thickness (224.9 +/- 116.9 microm) at the last visit was significantly thinner than the preoperative foveal retinal thickness (463.7 +/- 177.3 microm; P <.0001; Wilcoxon signed-rank test). The foveal retinal thickness did not decrease linearly but fluctuated: The mean postoperative retinal thickness had decreased significantly 7 days after surgery, then remained unchanged for approximately 1 month, and thereafter gradually decreased until 4 months. The intraoperative and postoperative complications included peripheral retinal tear in 3 of 65 (4.6%) eyes, postoperative rhegmatogenous retinal detachment in 1 of 65 (1.5%) eyes, neovascular glaucoma in 3 of 65 (5%) eyes, recurrent vitreous hemorrhage in 1 of 65 (1.5%) eyes, hard exudates in the center of the macula in 3 of 56 (4.6%) eyes, postoperative epiretinal membrane formation in 9 of 65 (13.8%) eyes, and a lamellar macular hole in 1 of 65 (1.5%) eyes. CONCLUSIONS: Vitrectomy for diabetic macular edema is an effective procedure for reducing the edema and improving visual acuity. Because the postoperative reduction in retinal thickness is not complete until 4 months, the assessment of vitrectomy on foveal thickness should not be made until this time. In addition, there are severe complications from vitrectomy for diabetic macular edema, and careful preoperative and postoperative examinations and surgical methods are required.     

Foveal photoreceptor layer in eyes with persistent cystoid macular edema associated with branch retinal vein occlusion

PURPOSE: To study the correlation of visual acuity and the foveal photoreceptor layer in eyes with persistent cystoid macular edema associated with branch retinal vein occlusion (BRVO). DESIGN: Retrospective chart review. METHODS: We studied retrospectively the medical records of 42 eyes of 42 patients with persistent cystoid macular edema secondary to BRVO, eyes in which the foveal thickness was greater than 250 microm at final examination. On the vertical image obtained by optical coherence tomography at the final examination, we measured thickness of the foveal photoreceptor layer that was beneath the foveal cystoid spaces. We also assessed status of the junction between inner and outer segments of the photoreceptors (IS/OS) in the fovea. RESULTS: The photoreceptor layer beneath the foveal cystoid spaces was detected as a distinct layer with thickness varying between 33 microm and 124 microm (mean, 71.1 +/- 26.8 microm). Final visual acuity showed no correlation with total foveal thickness (r = 0.336, P = .092). However, it did show a close correlation with thickness of the foveal photoreceptor layer (r = -0.571, P < .0001). Of the 42 eyes, 15 showed a continuous IS/OS line in the fovea. Visual acuity in these eyes with a continuous IS/OS line in the fovea was significantly better than that in eyes with a discontinuous or interrupted IS/OS line (P < .0001). CONCLUSIONS: Both the thickness and the integrity of the foveal photoreceptor layer are associated with visual function in eyes with persistent cystoid macular edema associated with BRVO.     

Topography of diabetic macular oedema compared with fluorescein angiography

PURPOSE: To compare the amount and pattern of fluorescein leakage in diabetic macular oedema with the retinal thickness maps obtained with the retinal thickness analyser (RTA) and optical coherence tomography (OCT). METHODS: A consecutive series of 30 eyes from 30 patients with diabetic macular oedema was included. On fluorescein angiography (FA) the macula was analysed in 10 subfields as defined by the ETDRS. The amount and source of leakage for each field were determined. Retinal thickness was measured by OCT and RTA maps in each of the 10 fields and compared with the FA grading. RESULTS: Foveal retinal thickness on OCT was most influenced by the overall FA leakage, which was the only significant covariate on multivariate analysis. The source and amount of leakage correlated significantly with the topography of retinal thickness in the four peripheral fields between 1500 microm and 3000 microm from the macular centre (r = 0.54, p = 0.002). The mean amount and source of leakage in those fields also showed the highest correlation with central macular thickness on OCT (r = 0.46, p = 0.01). Similar results were obtained by RTA when excluding ischaemic cases (r = 0.44, p = 0.04). For both instruments, FA leakage within the four central fields < 1500 microm did not correlate significantly with retinal thickness. Thickness by OCT and RTA were highly correlated with one another for central macular measurements (r = 0.73, p < 0.001), but correlated poorly in the peripheral fields. Overall, OCT measurements correlated more highly with FA. CONCLUSIONS: Optical coherence tomography and RTA thickness measurements can be used to identify patients for further examination. Fluorescein angiography leakage in the outer ETDRS fields correlates best with central thickness and retinal thickness topography by OCT.     

Effects of pseudophakic lens capsule opacification on optical coherence tomography of the macula

PURPOSE: To report observations on the influence of posterior lens capsule opacification on optical coherence tomographic imaging quality and measurements of macular thickness. METHODS: The retrospective study included 13 eyes in 12 patients of which 2 eyes had a healthy macula and 11 eyes had maculopathy. In all eyes posterior lens capsule fibrosis was present. A clinical examination including biomicroscopy of the macula and an in-vivo macular optical coherence tomography (OCT) before and after YAG-laser membranotomy had been performed. RESULTS: Foveal retinal thickness before and after membranotomy were highly correlated (R = 0.98), and no systematic difference was found between values obtained before vs. after membranotomy (mean thickness 318.7 +/- 92.7 microm vs. 322.2 +/- 97.4 microm; p = 0.221). The signal-to-noise ratio increased in 11 out of 13 eyes after membranotomy (mean signal-to-noise ratio before 47.1 +/- 6.6 dB vs. 52.6 +/- 4.0 dB after; p = 0.004, the change ranging from -1.5 dB to 17 dB). CONCLUSIONS: The qualitative effect of the posterior lens capsule opacification on the OCT-scan consists primarily of a loss of signal and consequently of intraretinal detail, whereas total foveal retinal thickness seems to be reliably assessed even when posterior lens capsule opacification interfering with the biomicroscopic evaluation of retinal edema are present. YAG-laser membranotomy results in a measurable improvement in the OCT signal-to-noise ratio, but OCT seems to yield reliable measurements of foveal retinal thickness before treatment. Consequently the OCT seems to reliably diagnose a macular thickening although not the type of this until after removal of the posterior lens capsule opacification.     

光学相干断层成像术观察超声乳化白内障吸除术后黄斑变化

目的　探讨超声乳化白内障吸除术后黄斑形态的变化及其可能的影响因素。方法　对行超声乳化白内障吸除术 ,且术前无合并症、术中无并发症发生的单纯老年性白内障患者 80例 (80只眼 )于术前和术后 1周分别行光学相干断层成像术 (opticalcoherencetomography ,OCT)检查 ;按术中使用的超声能量高低分成 2个组。观察黄斑中心凹视网膜厚度的变化及其与术中超声能量、术后前房炎性反应和视力的关系。结果　 80只眼黄斑中心凹视网膜平均厚度术前为 (14 2 9± 16 7) μm ,术后为 (15 7 9± 36 7) μm ,两者比较差异无显著意义 (P >0 0 5 )。术后 3只眼出现黄斑水肿 ,11只眼出现房水中度闪光 ,黄斑中心凹视网膜平均厚度术前为 (139 9± 11 3) μm ,术后为 (197 6± 36 9) μm ,两者比较差异有显著意义 (t =2 75 1,P <0 0 5 )。低能量组术后黄斑中心凹视网膜平均厚度为 (15 6 2± 18 3) μm ,高能量组为 (172 6± 32 9) μm ,两者比较差异有显著意义 (t=2 4 11,P <0 0 5 )。术后最佳矫正视力与黄斑中心凹视网膜厚度呈负相关性 (r=- 0 82 ,P <0 0 5 )。结论　超声乳化白内障吸除术可导致术眼黄斑中心凹视网膜厚度增加及黄斑水肿 ;术中高超声能量可明显影响术后黄斑中心凹视网膜的形态 ;术后黄斑中心     

Retinal thickness in healthy and diabetic subjects measured using optical coherence tomography mapping software

PURPOSE: To define the normal retinal thickness in healthy subjects using optical coherence tomography (OCT) mapping software and to assess the ability of OCT to detect early macular thickening in diabetic patients. METHODS: Six radial scans centered on the fixation point were done on 60 healthy eyes and 70 eyes of 35 diabetic patients without macular edema on biomicroscopy. Retinal thickness was measured automatically with OCT mapping software. Mean retinal thickness was compared in subgroups of healthy patients based on age, sex, and eye, and in the eyes of diabetic patients and healthy subjects. Thickening was diagnosed if mean retinal thickness of an area was greater than the mean thickness + 2SD in the corresponding area in healthy subjects; or if the difference between right and left eye exceeded the mean difference + 2 SD in a given area in healthy subjects. RESULTS: In healthy subjects, mean retinal thickness in the central macular area 1000 microm in diameter was 170+/-18 microm. There was no significant difference according to age, or left or right eye, but central macular thickness was significantly greater in men than women (p=0.0139). No difference was observed between the eyes of healthy subjects and diabetic patients without macular edema on biomicroscopy, but OCT detected early macular thickening in 12 diabetic eyes. CONCLUSIONS: In this study average retinal thickness and mean local variations in a normal population were defined using a commercially available mapping software. OCT seems a sensitive tool for detecting early retinal thickening.