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.

Comparison of optical coherence tomography and fundus photography for measuring the optic disc size.

PURPOSE: To assess the agreement and repeatability of optic nerve head (ONH) size measurements by optical coherence tomography (OCT) as compared to conventional planimetry of fundus photographs in normal eyes. METHODS: For comparison with planimetry the absolute size of the ONH of 25 eyes from 25 normal subjects were measured by both OCT and digital fundus photography (Zeiss FF camera 450). Repeatability of automated Stratus OCT measurements were investigated by repeatedly measuring the optic disc in five normal subjects. RESULTS: Mean disc size was 1763 +/- 186 vertically and 1632 +/- 160 microm horizontally on planimetry. On OCT, values of 1772 +/- 317 microm vertically (p = 0.82) and a significantly smaller horizontal diameter of 1492 +/- 302 microm (p = 0.04) were obtained. The 95% limits of agreement were (-546 microm; +527 microm) for vertical and (-502 microm; +782 microm) for horizontal planimetric compared to OCT measurements. In some cases large discrepancies existed. Repeatability of automatic measurements of the optic disc by OCT was moderately good with intra-class correlation coefficients (ICC) of 0.78 horizontally and 0.83 vertically. The coefficient of repeatability indicating instrument precision was 80 microm for horizontal and 168 microm for vertical measurements. CONCLUSIONS: OCT can be used to determine optic disc margins in moderate agreement with planimetry in normal subjects. However, in some cases significant disagreement with photographic assessment may occur making manual inspection advisable. Automatic disc detection by OCT is moderately repeatable.

Mapping of the retinal pigment epithelium in exudative age related macular degeneration.

PURPOSE: To evaluate a novel technique for three-dimensional mapping of the retinal pigment epithelium (RPE) layer in patients with subfoveal choroidal neovascularization (CNV) due to age-related macular degeneration. METHODS: Scanning with a recent generation retinal thickness analyzer (RTA) was performed in consecutive patients undergoing fluorescein angiography. From a 3 x 3 mm area centered on the fovea, three-dimensional area maps of the RPE level were calculated by external spreadsheet software. Included were 18 eyes with classic CNV, 18 eyes with occult CNV and 18 eyes from age-matched normal subjects. Repeatability was assessed by measuring 17 eyes with CNV 3 times. In ten additional patients, RTA imaging results were compared with cross-sections obtained by optical coherence tomography. RESULTS: By both methods, distinctive changes in RPE level maps were observed in classic and occult CNV. In classic CNV with the lesion extending over the RPE, only focal irregularities in the anteriorly displaced RPE surface were observed. In contrast, mapping of occult CNV showed a more irregular displacement of the RPE layer. The RPE map standard deviation indicating surface irregularity differed statistically significantly between the groups, with coefficients of variance of 5.9% for controls, 6.1% for classic and 8.8% for occult CNV (P < 0.001). Regarding repeatability, RPE level maps showed 1.2% coefficient of variance and an intra-class correlation coefficient of 0.87 for triplicate measurements in CNV patients. CONCLUSIONS: Topographic mapping of CNV lesions offers a fast, reproducible method for obtaining three-dimensional morphometric information on the RPE level and to quantify changes.

Age effect on retina and optic disc normal values.

PURPOSE: To investigate retinal thickness and optic disc parameters by the Retinal Thickness Analyzer (RTA) glaucoma program in older normal subjects and to determine any age effect. METHODS: Subjects over 40 years of age without any prior history of eye diseases were recruited. Only subjects completely normal on clinical ophthalmologic examination and on visual field testing by Humphrey Field Analyzer (HFA) using the SITA 24-2 program were included. A total of 74 eyes from 74 subjects with even age distribution over the decades were enrolled and underwent topographic measurements of the posterior pole and of the optic disc by RTA. The 'glaucoma full' program in software version 4.11B was applied. RESULTS: Mean patient age was 59.9 +/- 10.3 years with a range from 40 to 80 years. The only parameter intraocular pressure (IOP) correlated with was retinal posterior pole asymmetry (r = 0.27, p = 0.02). IOP itself increased significantly with age (r = 0.341, p = 0.003). Mean defect and pattern standard deviation of the HFA did not correlate with any of the retinal or optic disc measurements. Increasing age correlated significantly with some of the morphologic measurements of the RTA: decreasing perifoveal minimum thickness (r = -0.258, p = 0.026), increased cup-to-disc area ratio (r = 0.302, p = 0.016) and increased cup area (r = 0.338 p = 0.007). CONCLUSIONS: An age effect exists for some of the retina and optic disc measurements obtained by the RTA.

[Presumed ocular histoplasmosis syndrome (POHS) in a non-endemic area]. / Presumed-Ocular-Histoplasmosis-Syndrom (POHS) in einem nichtendemischen Areal.

BACKGROUND: POHS is a chorioretinal disease rarely occurring in non-endemic areas. METHODS: We present the case of a 35-year old male patient with symptoms of dry eyes, but subjectively no other ocular complaints. However, visual acuity of the right eye was 20/20, but only 20/200 in the left eye. RESULTS: On fundoscopic examination both eyes showed alterations consistent with all four typical features of presumed ocular histoplasmosis syndrome. In both eyes in the mid-periphery punched-out chorioretinal spots were found, an extensive peripapillary atrophy and peripheral linear chorioretinal streaks were seen. Moreover, in the left eye an atrophic macular scar existed, presumably due to subretinal neovascularisation. The macula of the right eye was normal, serology testing for Histoplasma capsulatum negative. CONCLUSIONS: As the patient had never travelled to endemic areas such as the USA but exhibited all features of POHS, the case shows that POHS may also occur in European, non-endemic areas. This further supports the theory that other factors play a role in the etiopathology of this syndrome.