Atherosclerosis ; diagnosis ; Humans ; Tomography, Optical Coherence ; methods

INTRODUCTIONFor many years, ophthalmologists have looked at the optic nerve head to evaluate the status of glaucoma. Clinical examination of the optic nerve head and retinal nerve fibre layer (RNFL) is however, subjective and sometimes variable. Recent developments in computer-based imaging technologies have provided a means of obtaining quantitative measurements of the optic nerve head topography and peripapillary retinal nerve fibre layer thickness.

METHODSMultiple searches using Medline were carried out. Additional searches were made using reference lists of published papers and book chapters.

RESULTSStudies involving three imaging technologies namely, confocal scanning laser ophthalmoscopy, scanning laser polarimetry and optical coherence tomography were reviewed. Overall, these technologies were reproducible and demonstrate good sensitivity and specificity in the range of 70 to 80%. Inclusion of age and ethnicity normative database will make these technologies more effective in screening and diagnosis. Quantitative measurements provide useful parameters for monitoring of patients.

CONCLUSIONThere is no consensus on the best technology for assessing structural damage in glaucomatous optic neuropathy. Therefore, as with any investigation, the clinician should exercise clinical correlation and judgment before instituting the appropriate treatment.

Female ; Humans ; Middle Aged ; Ophthalmoscopy ; methods ; Optic Nerve ; Retina ; Sensitivity and Specificity ; Tomography, Optical ; methods ; Tomography, Optical Coherence

In order to extract the outlines of macular edema from OCT images of macular, and estimate the volume of edema, we have to accurately segment the macular edema region. In this paper, an improved PCNN algorithm was proposed to conduct the above process. Combined with the adaptive base threshold, and the simplified neural network parameters, a binary image of macular edema was produced. According to the principle of maximum image entropy, the optimal number of iterations was determined as 8, which was evaluated by its misclassification rate. Simulation showed that the proposed algorithm could extract the macular edema region rapidly and accurately, providing the basis for further OCT image analysis.
Algorithms ; Fluorescein Angiography ; methods ; Humans ; Macular Edema ; diagnostic imaging ; Radiography ; Tomography, Optical Coherence ; methods

According to the characteristics of OCT images for macula edema, we studied a method for segmentation of the macula edema. Based on the Chan-Vese model, we proposed an improved level-set algorithm. With defining the integer-valued signed function directly, the curve could evolute outward or inward by changing the inside neighboring rid points and outside neighboring grid points into each other. We realized image segmentation which is much faster than the method of Chan-Vese model and smoothness regularization. We segmented 45 images and extracted the macula edema of each image. After achieving good segmentation results, we estimated the volume of the macular edema. The method provides quantitative analytic tools for clinical diagnosis and therapy.
Algorithms ; Humans ; Image Interpretation, Computer-Assisted ; methods ; Macular Edema ; diagnosis ; pathology ; Tomography, Optical Coherence ; methods

No abstract available.
Dengue/*complications ; Female ; Humans ; Tomography, Optical Coherence/*methods ; Vision Disorders/*diagnosis ; *Visual Acuity ; *Visual Fields

PURPOSE: To assess efficacy of the Pentacam (PTC) and the anterior segment optical coherence tomography (AOCT) for detection of occludable angles. MATERIALS AND METHODS: Fourty-one eyes with gonioscopically diagnosed occludable angles and 32 normal open-angle eyes were included. Anterior chamber angle (ACA) and anterior chamber depth (ACD) were measured with PTC and AOCT. Receiver operating characteristic (ROC) curve was constructed for each parameter and the area under the ROC curve (AUC) was calculated. RESULTS: Values of ACA and ACD measured by PTC and AOCT were similar not only in normal open angle eyes but also in occludable angle eyes. For detection of occludable angle, the AUCs of PTC with ACA and ACD were 0.935 and 0.969, respectively. The AUCs of AOCT with ACA and ACD were 0.904 and 0.947, respectively. CONCLUSION: Both PTC and AOCT allow accurate discrimination between open and occludable angle eyes, so that they may aid to screening the occludable angles.
Aged ; Aged, 80 and over ; Anterior Chamber/*anatomy & histology ; Humans ; Middle Aged ; Tomography, Optical Coherence/*methods

According to the mechanism of spectral domain optical coherence tomography, this paper gives a design and development of a practical OCT imaging device based on slit-lamp microscopic widely-used in ophthalmology. The paper details the device's architecture and three key points in design: communication between PC and MCU, how to design modules of fixation lamp and reference arm and anti-interference measures.
Diagnostic Techniques, Ophthalmological ; instrumentation ; Equipment Design ; Tomography, Optical Coherence ; instrumentation ; methods

Aged ; Anterior Eye Segment ; pathology ; Female ; Glaucoma ; therapy ; Humans ; Pseudophakia ; therapy ; Tomography, Optical Coherence ; methods

OBJECTIVETo develop a spectral-domain optical coherence tomography (SD-OCT) system, for precisely imaging the accommodation of the anterior segment of the human eye.

METHODSDesign the SD-OCT system based on two Michelson interferometer by using the basic principal of weak coherent light interference and modular design of dual channel dual focus.

RESULTSThe system can provide simultaneous cross-sectional imaging of all the surfaces of the anterior segment of the eye including the cornea, anterior chamber, anterior and posterior surfaces of the crystalline lens. Thus, the dynamic change of modification of the curvatures can be calculated in real time.

CONCLUSIONSThe system was successfully tested in imaging accommodation, with high resolution and non contact. The preliminary results demonstrated the feasibility of this novel approach to measure the eye parameters.

Accommodation, Ocular ; Anterior Eye Segment ; physiology ; Humans ; Tomography, Optical Coherence ; methods

OBJECTIVEUsing the algorithm on the layered structure of the retina and quantitative analysis of the automatic segmentation technique is the key to the early diagnosis of glaucoma and other retinopathy on optical coherence tomography. Existing methods require high quality image and have low reliability. This paper used the improved complex nonlinear diffuse filtering and other methods to solve this problem.

METHODSThis paper includes algorithm such as automatic threshold, improved complex nonlinear diffusion filtering, morphological operations and peak detection. Use the method for the segmentation of 20 retinal layers images which acquired on the self-builder OCT system, the boundary of inner limiting membrane(ILM), outer nuclear layer(ONL), the photoreceptor segments(IS/ OS) and the RPE_ChCap layer are detected accurately. At last, the photoreceptor layer thickness is measured.

RESULTSThe results of segmentation and measurement are good corresponded with expert manual segmentation and measurements, retinal foveal measurements data is consistent with Zeiss Stratus OCT central retinal thickness 212+/-20 micro m.

CONCLUSIONThe algorithm proposed is prospective applied to clinical diagnosis of retinal diseases.

Algorithms ; Humans ; Retina ; anatomy & histology ; Software ; Tomography, Optical Coherence ; instrumentation ; methods