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

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

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

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

BACKGROUNDThin-flap laser in situ keratomileusis (LASIK) is the new trend of refractive error correction surgery, the formation of corneal flap is crucial for a success of LASIK surgery. This study aimed to assess and compare the variations of LASIK flap created by the IntraLase femtosecond laser, Moria One Use-Plus SBK and Moria M2 Single-Use 90 µm-head microkeratome using Anterior segment optical coherence tomography (Visante OCT).

METHODSOne hundred and sixty-one eyes of 81 consecutive patients were enrolled in this prospective study and randomly divided into three groups depending on the flap creation method: flap creation with the the IntraLase femtosecond laser (IntraLase group, 59 eyes), flap creation with the Moria One Use-Plus SBK (SBK group, 44 eyes), and flap creation with the Moria M2 Single-Use 90 µm-head microkeratome (M2SU90 group, 58 eyes). The nominal flap thickness was 110 µm for all patients and for the three devices. One month after surgery, Visante OCT was used to measure the flap thickness at 20 locations on each cornea and the results were assessed for uniformity, regularity, and accuracy.

RESULTSAt 1 month after surgery, the mean central flap thickness was (111 ± 3) µm in the IntraLase group, (114 ± 8) µm in the SBK group, and (118 ± 13) µm in the M2SU90 group respectively. The flaps in the IntraLase group and the SBK group were more regular, showing an almost planar configuration, than the meniscus-shaped flaps in the M2SU90 group. The maximum deviation from the intended flap thickness (110 µm) was 6 µm in the IntraLase group, 10 µm in the SBK group, and 20 µm in the M2SU90 group respectively. A difference greater than 20 µm was observed in 0.42% of measurements in the IntraLase group; 2.95% of the measurements in the SBK group and 21.12% of measurements in the M2SU90 group.

CONCLUSIONSThe flaps created by the IntraLase femtosecond laser and Moria One Use-Plus SBK are more uniform; more regular, and more accurate than those created by the Moria M2 Single-Use 90 µm-head microkeratome. The first two methods can make precise flaps for Sub-Bowman Keratomileusis.

Adolescent ; Adult ; Humans ; Keratomileusis, Laser In Situ ; methods ; Surgical Flaps ; Tomography, Optical Coherence

BACKGROUNDOptical coherence tomography (OCT) is a new imaging technique capable of obtaining high-resolution intravascular images of small vessels and has been widely used in interventional cardiology. However, application of OCT in peripheral pulmonary arteries in patients has been seldom documented.

METHODSThree patients who were highly suspected peripheral pulmonary arteries thrombi and had undergone CT pulmonary angiography but tested negative for thrombi in peripheral pulmonary arteries were enrolled. Subsequently, OCT imaging was performed in peripheral pulmonary arteries. The patients received more than three-month anticoagulative treatment if thrombi were detected by OCT. Thereafter, OCT re-evaluation of the thrombolized blood vessels detected earlier was performed. The changes of thrombi before and after anticoagulative treatment were compared.

RESULTSThree patients underwent OCT imaging of peripheral pulmonary arteries. Thrombi were found in most of imaged vessels in these patients. Red and white thrombi can be differentiated, according to features of the thrombus on OCT images. After anticoagulation treatment, these patients' symptoms and hypoxemia improved. Repeated OCT imaging showed that most thrombi disappeared or became smaller.

CONCLUSIONOCT may be used as a potential tool for detecting peripheral pulmonary artery thrombi and differentiating red thrombi from white ones.

Adult ; Female ; Humans ; Male ; Middle Aged ; Pulmonary Embolism ; diagnosis ; Tomography, Optical Coherence ; methods