[Methodological advancements. Ultrahigh-resolution OCT]

[Three-dimensional optical coherence tomography for evaluating the retinal architecture before and after surgery for vitreomacular traction.]

PURPOSE: To investigate the morphology of the vitreoretinal interface before and after delamination of epiretinal membranes using three-dimensional volumetric high-resolution optical coherence tomography (HROCT). METHODS: Extension and intensity of vitreomacular traction due to epiretinal membranes (ERM) and the architecture of retinal layers in 14 eyes of 14 patients were evaluated preoperatively using high-resolution raster scanning OCT (Cirrus prototype, resulting in a 6x6-mm field, 2 mm in depth). Additionally, stratus OCT, visual acuity testing, and fundus photography were performed. Standardized prospective follow-up was done continuously at 1, 4, and 7 days and 1 and 3 months postoperatively. RESULTS: The ERM appeared tightly adherent to the retinal surface in 85% of cases, but nevertheless could be differentiated from the retinal surface in 100%. Vertical traction forces from the ERM to the intraretinal layers were found in 93% of cases. Structural alteration of the retina was seen neither immediately following surgery nor during follow-up. After a mean of 4 weeks, the retinal structural integrity had recovered with resolution of the traction-induced deviations seen preoperatively. Mean preoperative visual acuity increased from 0.4+/-0.2 Snellen preoperatively to 0.5+/-0.2 Snellen after 3 months. Mean retinal thickness decreased from 482+/-84 mum to 328+/-80 mum after 3 months (HROCT). CONCLUSIONS: Three-dimensional HROCT imaging enables unprecedented in vivo identification of the extension and dynamics of epiretinal traction. Epiretinal membranes are clearly delineated in the en face view, and the distribution of traction forces throughout the intraretinal layers is identified down to the level of the retinal pigment epithelium. During follow-up, quantification of substantial release in retinal traction was possible and correlated to conventional OCT findings.

Spectral oximetry assessed with high-speed ultra-high-resolution optical coherence tomography

We use Fourier domain optical coherence tomography (OCT) data to assess retinal blood oxygen saturation. Three-dimensional disk-centered retinal tissue volumes were assessed in 17 normal healthy subjects. After removing DC and low-frequency a-scan components, an OCT fundus image was created by integrating total reflectance into a single reflectance value. Thirty fringe patterns were sampled; 10 each from the edge of an artery, adjacent tissue, and the edge of a vein, respectively. A-scans were recalculated, zeroing the DC term in the power spectrum, and used for analysis. Optical density ratios (ODRs) were calculated as ODR(Art)=ln(Tissue(855)Art(855))ln(Tissue(805)Art(805)) and ODR(Vein)=ln(Tissue(855)Vein(855))ln(Tissue(805)Vein(805)) with Tissue, Art, and Vein representing total a-scan reflectance at the 805- or 855-nm centered bandwidth. Arterial and venous ODRs were compared by the Wilcoxon signed rank test. Arterial ODRs were significantly greater than venous ODRs (1.007+/-2.611 and -1.434+/-4.310, respectively; p=0.0217) (mean+/-standard deviation). A difference between arterial and venous blood saturation was detected. This suggests that retinal oximetry may possibly be added as a metabolic measurement in structural imaging devices.

Klassifikation biomedizinischer Forschungsberichte als Grundlage evidenzbasierter Medizin in der Augenheilkunde

BACKGROUND

Evidence-based medicine requires careful appraisal of published data derived from experimental and clinical studies. Based on classification of biomedical research reports, evidence levels can be determined and recommendations for therapeutic decisions can be made.

METHODS

A classification system for clinical studies was developed. It was evaluated in classifying the reports published in Der Ophthalmologe during 2003-2004 (study design: descriptive cross-sectional study, case series).

RESULTS

In the 2-year interval, 70 longitudinal and 95 cross-sectional studies were published. The vast majority of the longitudinal studies were interventional cohort studies. Not considering case reports, 73% of the original articles were longitudinal prospective studies, 1% were retrospective (case-control) studies, and 26% were cross-sectional studies.

CONCLUSIONS

The study design of all published articles could be classified using the classification system. This classification system proves to be applicable in the context of clinical studies in ophthalmology and may be helpful in the process of critical appraisal of the literature and synthesis of clinical evidence and an evidence-based recommendation.

Makulaforamen

The theory of macular hole pathogenesis, which had so far been based on biomicroscopy, has been considerably altered by optical coherence tomography. The precise presentation of vitreofoveal pathology shows that forces acting in different directions are associated with different stages of the disease, making surgical treatment adapted to the different stages possible. Some surgical procedures are still controversial, and there is still no gold standard in macular hole surgery. Especially no agreement exists on the benefit of internal limiting membrane peeling, possibly assisted by staining with indocyanine green. Also details of endotamponade and postoperative positioning are controversial. Therefore, the method of surgical treatment depends a lot on the individual surgeon. This review summarizes the broad spectrum of the literature and the present knowledge in this field.