Paola Salvetti

Bimodal spatial distribution of macular pigment: evidence of a gender relationship

The spatial distribution of the optical density of the human macular pigment measured by two-wavelength autofluorescence imaging exhibits in over half of the subjects an annulus of higher density superimposed on a central exponential-like distribution. This annulus is located at about 0.7 degrees from the fovea. Women have broader distributions than men, and they are more likely to exhibit this bimodal distribution. Maxwells spot reported by subjects matches the measured distribution of their pigment. Evidence that the shape of the foveal depression may be gender related leads us to hypothesize that differences in macular pigment distribution are related to anatomical differences in the shape of the foveal depression.

Artifacts in automatic retinal segmentation using different optical coherence tomography instruments.

Purpose: The purpose of this study was to compare and evaluate artifact errors in automatic inner and outer retinal boundary detection produced by different time-domain and spectral-domain optical coherence tomography (OCT) instruments. Methods: Normal and pathologic eyes were imaged by six different OCT devices. For each instrument, standard analysis protocols were used for macular thickness evaluation. Error frequencies, defined as the percentage of examinations affected by at least one error in retinal segmentation (EF-exam) and the percentage of total errors per total B-scans, were assessed for each instrument. In addition, inner versus outer retinal boundary delimitation and central (1,000 &mgr;m) versus noncentral location of errors were studied. Results: The study population of the EF-exam for all instruments was 25.8%. The EF-exam of normal eyes was 6.9%, whereas in all pathologic eyes, it was 32.7% (P < 0.0001). The EF-exam was highest in eyes with macular holes, 83.3%, followed by epiretinal membrane with cystoid macular edema, 66.6%, and neovascular age-related macular degeneration, 50.3%. The different OCT instruments produced different EF-exam values (P < 0.0001). The Zeiss Stratus produced the highest percentage of total errors per total B-scans compared with the other OCT systems, and this was statistically significant for all devices (P ≤ 0.005) except the Optovue RTvue-100 (P = 0.165). Conclusion: Spectral-domain OCT instruments reduce, but do not eliminate, errors in retinal segmentation. Moreover, accurate segmentation is lower in pathologic eyes compared with normal eyes for all instruments. The important differences in EF among the instruments studied are probably attributable to analysis algorithms used to set retinal inner and outer boundaries. Manual adjustments of retinal segmentations could reduce errors, but it will be important to evaluate interoperator variability.

Spectral-Domain Optical Coherence Tomography as an Indicator of Fluorescein Angiography Leakage from Choroidal Neovascularization

PURPOSE To evaluate spectral-domain optical coherence tomography (SD-OCT) findings that predict angiographic leakage in choroidal neovascularization (CNV). METHODS SD-OCT and fluorescein angiography (FA) images of 93 eyes of 93 patients were retrospectively analyzed. All patients were previously treated with anti-vascular endothelial growth factor agents for CNV from age-related macular degeneration. FA images were analyzed to assess the presence of leakage. SD-OCT images were analyzed to identify the overall presence of fluid, as well as specific patterns of fluid presentation, including intraretinal cystic spaces (ICS), retinal pigment epithelium detachment (PED), and neurosensory detachment (NSD). The presence of ultrastructural features such as intraretinal hyperreflective flecks and the inherent reflectivity and boundary definition of the subretinal material were evaluated. Both the association and the sensitivity, specificity, and both positive and negative predictive values of SD-OCT findings compared with FA leakage were calculated. RESULTS A statistically significant association between SD-OCT findings and FA leakage was found for eyes that displayed fluid, NSD, intraretinal flecks, and low reflectivity or undefined boundaries from subretinal material, and not for PED or ICS. Sensitivity and specificity for SD-OCT findings were, respectively: 94% and 27% for fluid; 68% and 88% for NSD; 81% and 83% for intraretinal flecks; 63% and 92% for undefined boundaries of subretinal material; and 94% and 87% for low reflectivity from subretinal material. CONCLUSIONS The evidence of fluid on SD-OCT is sensitive but nonspecific in identifying FA leaky CNV. The assessment of neurosensory detachment as well as other ultrastructural elements may increase the specificity of analysis.

Displayed reflectivity of choroidal neovascular membranes by optical coherence tomography correlates with presence of leakage by fluorescein angiography.

Purpose: To evaluate and correlate the displayed optical reflectivity of choroidal neovascularization (CNV) subretinal material on spectral-domain optical coherence tomography with the presence of dye leakage on fluorescein angiography (FA). Methods: Thirty-nine eyes of 39 patients with a diagnosis of predominantly classic CNV from age-related macular degeneration underwent simultaneous spectral-domain optical coherence tomography and FA imaging. Eight patients had a newly diagnosed untreated CNV. Thirty-one patients had already been treated with anti-vascular endothelial growth factor agents. In 18 of these eyes, CNV lesions showed persistent leakage on FA. In 13 eyes, CNV lesions did not show leakage by FA. Subretinal CNV material boundaries visualized on spectral-domain optical coherence tomography B-scans were manually traced, and optical reflectivity was calculated using the mean grayscale value. To account for variable image brightness, the retinal pigment epithelial reflectivity was measured. The absolute difference between CNV material and retinal pigment epithelial reflectivity (ΔREF) from the three groups (newly diagnosed CNV, previously treated CNV showing FA leakage, and previously treated CNV not showing FA leakage) was compared. Results: In untreated lesions, ΔREF was significantly higher compared with previously treated, but still leaky CNV (P < 0.0001). Lesions showing FA leakage had significantly higher ΔREF compared with those that did not display leakage (P < 0.0001). Conclusion: The displayed reflectivity of subretinal CNV material in spectral-domain optical coherence tomography appears to be an important parameter that can provide information regarding the FA leakage status.

Combining photodynamic therapy and feeder vessel photocoagulation: a pilot study.

Patients receiving photodynamic therapy (PDT) with verteporfin (Visudyne ®, Novartis AG), a new treatment for subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) and pathologic myopia, should be scheduled for follow-up every 12 weeks (±2 weeks) after the initial treatment. However, important data from clinical practice and from small series studies suggest that this period between treatment may be too long for some patients. In this pilot study we explore the safety and the possibility of improving the extent and duration of PDT benefit using feeder vessel treatment (FVT). This study suggests that the combination of verteporfin therapy and FVT is a safe procedure; it also suggests a possibility for prolonging the effect of verteporfin therapy.