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PubMed2005

Time-domain scanning optical mammography: II. Optical properties and tissue parameters of 87 carcinomas.

Within a clinical trial on scanning time-domain optical mammography reported on in a companion publication (part I), craniocaudal and mediolateral projection optical mammograms were recorded from 154 patients, suspected of having breast cancer. Here we report on in vivo optical properties of the subset of 87 histologically validated carcinomas which were visible in optical mammograms recorded at two or three near-infrared wavelengths. Tumour absorption and reduced scattering coefficients were derived from distributions of times of flight of photons recorded at the tumour site employing the model of diffraction of photon density waves by a spherical inhomogeneity, located in an otherwise homogeneous tissue slab. Effective tumour radii, taken from pathology, and tumour location along the compression direction, deduced from off-axis optical scans of the tumour region, were included in the analysis as prior knowledge, if available. On average, tumour absorption coefficients exceeded those of surrounding healthy breast tissue by a factor of about 2.5 (670 nm), whereas tumour reduced scattering coefficients were larger by about 20% (670 nm). From absorption coefficients at 670 nm and 785 nm total haemoglobin concentration and blood oxygen saturation were deduced for tumours and surrounding healthy breast tissue. Apart from a few outliers total haemoglobin concentration was observed to be systematically larger in tumours compared to healthy breast tissue. In contrast, blood oxygen saturation was found to be a poor discriminator for tumours and healthy breast tissue; both median values of blood oxygen saturation are the same within their statistical uncertainties. However, the ratio of total haemoglobin concentration over blood oxygen saturation further improves discrimination between tumours and healthy breast tissue. For 29 tumours detected in optical mammograms recorded at three wavelengths (670 nm, 785 nm, 843 nm or 884 nm), scatter power was derived from transport scattering coefficients. Scatter power of tumours tends to be larger than that of surrounding healthy breast tissue, yet the 95% confidence intervals of both medians overlap.

Breast Neoplasms↗

PubMed2006

Three dimensional optic disc visualisation from stereo images via dual registration and ocular media optical correction.

BACKGROUND/AIMS: The three dimensional (3-D) visualisation of the optic disc in true colour will give essential meaning in clinical application. It is not only useful for clinicians in the evaluation of the condition of the optic disc, but it also simplifies the pathological diagnosis and disease progression monitoring. This paper describes a complete 3-D optic disc reconstruction method from a pair of stereo images by a series of robust procedures including camera calibration, image registration, depth recovery, and ocular media optical inclusion. METHODS: Two registration techniques (correlation and feature based methods) are combined together to prune the uncertain matching points in order to improve the overall accuracy of registration. The ocular media within the eyeball are lump modelled as a single lens and integrated into the reconstruction process to obtain an accurate 3-D optic disc image. CONCLUSION: The recovered 3-D optic disc images show good consistency and compatibility when compared with the results from Heidelberg retina tomography (HRT) under clinical validation, with an additional advantage of implementing a more economical and conventional mode of retinal image acquisition.

Algorithms↗

PubMed1998

Optical coherence tomography of pneumatic displacement of optic disc pit maculopathy.

BACKGROUND: The authors have previously concluded that fluid from an optic disc pit creates an inner layer separation (ILS) of the retina. An outer layer detachment (OLD) centred on the macula is a secondary phenomenon that causes a dense central scotoma. Pneumatic displacement of the OLD effects an improvement in central vision. Pathology to confirm these conclusions is lacking. Intraretinal images obtained by optical coherence tomography (OCT), however, are confirmatory. METHODS: Three patients with optic disc pit maculopathy were studied with stereoscopic photographs, visual fields, and OCT before and after intravitreal gas was injected to displace the central retinal elevation to below the inferior temporal vascular arcade. RESULTS: Preoperatively, OCT demonstrated an ILS that connected with the optic disc pit. External to it was an OLD that centred on the fovea and did not connect with the optic disc pit. Pneumatic displacement of the OLD was accompanied by an improvement in central vision. Long term follow up indicates that the effect of displacement may be temporary. CONCLUSION: OCT confirmed the two layer structure of optic disc pit maculopathy and that the improvement in central vision after pneumatic displacement coincides with a reattachment of the OLD in the macula. It also supports the hypothesis that the ILS, which persists, provides a conduit for the continuous flow of fluid from the pit to the displaced retinal elevation.

Adult↗

PubMed2000

A new digital optic disc stereo camera: intraobserver and interobserver repeatability of optic disc measurements.

AIMS: To investigate the intraobserver and interobserver repeatability of optic disc measurement using a new digital optic disc stereo camera. METHODS: 112 consecutive new patients presenting to a glaucoma service had dilated optic disc photography performed using a new digital stereo camera (Discam, Marcher Enterprises Ltd, Hereford). The images were analysed by two masked observers using a stereo viewer and computer simulated stereopsis. Vertical and horizontal cup:disc ratios (CDR), cup area:disc area, and cup circumference:disc circumference were computed. Intraobserver and interobserver repeatability analyses were performed. Intraclass correlation coefficients (ICC) and 95% tolerance for change (TC) were computed. RESULTS: 220 optic discs were photographed, of which 196 were suitable for analysis (10 were of poor image quality and 14 had anomalous discs). Mean age of patients was 65 years, 60 were male and 48 female. For intraobserver measurements of: horizontal CDR, ICC = 0.94, TC = 0.11 (15% of range); vertical CDR, ICC = 0.92, TC = 0.14 (16% of range); cup area:disc area, ICC = 0.95, TC = 0.10 (13% of range), and cup circumference:disc circumference, ICC = 0.95, TC = 0.09 (14% of range). For interobserver measurements of: horizontal CDR, ICC = 0.89, TC = 0.14 (19% of range); vertical CDR, ICC = 0.90, TC = 0.14 (16% of range); cup area:disc area, ICC = 0.92, TC = 0.13 (16% of range), and cup circumference:disc circumference, ICC = 0.90, TC = 0.12 (17% of range). Systematic bias between observers was within acceptable limits. CONCLUSIONS: Digital stereo disc photography and analysis provide repeatable measures of optic disc variables. The results compare favourably with ophthalmoscopic and stereophotographic methods of assessment of the optic disc.

Aged↗

PubMed2005

Benign versus malignant breast masses: optical differentiation with US-guided optical imaging reconstruction.

PURPOSE: To investigate prospectively the feasibility of using optical tomography with ultrasonographic (US) localization to differentiate malignant from benign breast masses and to compare optical tomography with color Doppler US. MATERIALS AND METHODS: The study was approved by the local internal review board committee and by the Human Subjects Research Review Board of Army Medical Research and Materiel Command. Signed informed consent was obtained, and the study was HIPAA compliant. Between May 2003 and March 2004, 65 consecutive women (mean age, 51 years; age range, 24-80 years) with 81 breast lesions underwent US-guided biopsy and were scanned with a combined imager. The hand-held probe, which consisted of a centrally located US transducer surrounded by near-infrared sensors, was used to simultaneously acquire coregistered US images and optical data. The lesion location obtained at US was used to guide optical imaging reconstruction. Light absorption was measured at two wavelengths. From these measurements, tumor angiogenesis was assessed on the basis of calculated total hemoglobin concentration. A Student t distribution was used to calculate the statistical significance of mean maximum and mean average hemoglobin concentrations obtained in malignant and benign lesion groups, and P < .001 was considered to indicate a statistically significant difference. RESULTS: Biopsy results revealed eight early stage invasive carcinomas (malignant group) and 73 benign lesions (benign group). The mean maximum and mean average hemoglobin concentrations in the malignant group were 122 micromol/L +/- 26.8 (+/- standard deviation) and 88 micromol/L +/- 24.5, respectively. The mean maximum and mean average hemoglobin concentrations in the benign group were 55 micromol/L +/- 24.8 and 38 micromol/L +/- 17.4, respectively. Both the maximum and average total hemoglobin concentrations were significantly higher in the malignant group compared with the benign group (P < .001). When a maximum hemoglobin concentration of 95 micromol/L was used as the threshold value, the sensitivity, specificity, positive predictive value, and negative predictive value of optical tomography were 100%, 96%, 73%, and 100%, respectively, and the sensitivity, specificity, positive predictive value, and negative predictive value of color Doppler US were 63%, 69%, 19%, and 94%, respectively. CONCLUSION: Findings indicate that optical tomography with US localization is feasible for differentiating benign and early stage malignant breast lesions.

Adult↗

PubMed2006

Optic disk size and optic disk-to-fovea distance in preterm and full-term infants.

PURPOSE: Few studies have assessed optic disk and retinal morphology in infants. Here the optic disk and optic disk-to-fovea distance were measured in preterm and full-term infants in vivo. METHODS: Optic disk (OD) dimensions and the center-to-center distance between the OD and the macula were measured using digital imaging in infants undergoing routine ophthalmic examinations. Postmenstrual age of the mother at the time of examination ranged from 32 to 50 weeks. From each image, the OD-to-fovea distance (ODF) and the OD height (ODH) and OD width (ODW) were measured. RESULTS: In 51 retinal images from 51 infants, mean +/- SD values obtained were 4.4 +/- 0.4 mm (ODF), 1.41 +/- 0.1 9 mm (ODH), and 1.05 +/- 0.13 mm (ODW). These dimensions did not change significantly over the age range studied. The mean value for the ratio between ODF and mean OD diameter (ODF/DD) was 3.76. CONCLUSIONS: Results of this in vivo study suggest that though the optic nerve head diameter increases by more than 50%, only limited growth occurs at the highly organized area of the posterior pole from birth to adulthood. This study discusses the finding of a large-angle kappa in infants and the use of a disk macula/disk diameter ratio in the diagnosis of optic nerve hypoplasia.

Birth Weight↗

PubMed2002

Optical resolution by preferential crystallization of (RS)-2-benzoylamino-2-benzyl-3-hydroxypropanoic acid and its use in synthesizing optically active 2-amino-2-methyl-3-phenylpropanoic acid.

To synthesize optically active 2-amino-2-methyl-3-phenylpropanoic acid (1), (RS)-2-benzoylamino-2-benzyl-3-hydroxypropanoic acid [(RS)-2] was first optically resolved using cinchonidine as a resolving agent to yield optically pure (S)- and (R)-2 in yields of about 70%, based on half of the starting amount of (RS)-2. Next, the racemic structure of (RS)-2 was examined based on melting point, solubility, IR spectrum, and binary and ternary phase diagrams, with the aim of optical resolution by preferential crystallization of (RS)-2. Results indicated that the (RS)-2 exists as a conglomerate at room temperature, although it forms a racemic compound at the melting point. The optical resolution by preferential crystallization yielded (S)- and (R)-2 with optical purities of about 90%, which were fully purified by recrystallization. After O-tosylation of (S)- and (R)-2, reduction by zinc powder and sodium iodide gave (R)- and (S)-1, respectively.

Crystallization↗

PubMed2002

Dynamic optical coherence tomography in studies of optical clearing, sedimentation, and aggregation of immersed blood.

The concept of refractive-index matching to enhance the optical penetration depth of whole blood is discussed on the basis of in vitro studies that used the technique of near-infrared optical coherence tomography. It was found that optical clearing of blood is defined not only by refractive-index matching but also by changes in the size of red blood cells and in their aggregation ability when chemicals are added. For example, in whole blood diluted to twice its volume by saline with the addition of 6.5% glycerol, the total attenuation coefficient was reduced from 4.2 to 2.0 mm(-1), and the optical penetration at 820 nm was correspondingly increased to 117%. For the other agents tested (glucose, dextrans, propylene glycol, and trazograph) the enhancement of penetration was 20-150.5%. In the blood sedimentation study, regular or irregular oscillations or jumps of the red-blood cell-plasma boundary were observed. The 1-min time period of regular oscillations correlated well with the kinetics of the aggregation process as described by the two subsequent stages of formation of linear and three-dimensional aggregates. The results also showed that optical clearing of blood by osmotic agents is potentially useful not only in blood sedimentation and aggregation studies but also in intravascular optical coherence tomography imaging techniques.

Adult↗

PubMed1977

Electron microscopy of the mouse optic nerve: a quantitative study of the total optic nerve fibers.

The total number of myelinated and unmyelinated nerve fibers was counted in a montage of electron micrographs prepared to cover the entire profile of the mouse optic nerve in transverse section. Many astrocytic processes form a barrier structure all around the optic nerve. As a whole, the mouse optic nerve consists of one fascicle where the nerve fibers, the glia cells and their processes, and the capillaries are fitted closely together to fill substantially all of the available space. No tissue space accompanied with connective tissue septa penetrates into the fascicle, except for those situated around the arteriole and venule. The total number of 64,746 myelinated nerve fibers in the optic nerve in one side was counted. This corresponds to about 98.8% of the total number of the optic nerve fibers. The total number of 807 unmyelinated nerve fibers was also counted. This corresponds to about 1.2% of the total nerve fibers. The external diameter of every myelinated fiber, including the myelin sheath, was measured on the montage micrograph and its frequency distribution was examined. The diameter of the myelinated fibers ranges from 0.3 to 4.2 mu and its mean value is 0.96 mu. The frequency distribution of fiber diameter is unimodal with a peak at 0.7 to 0.9 mu. A regional heterogeneity in fiber size is found in the optic nerve. The nerve fibers in the peripheral area of the nerve are relatively small and uniform in diameter, whereas those in the central area show a fairly wide range in diameter.

Animals↗

PubMed2004

Optic disc imaging by Heidelberg retinal tomogram in congenital optic disc anomaly.

We evaluated two cases of congenital optic disc anomaly with the Heidelberg Retinal Tomograph (HRT) that could be mistaken for glaucomatous optic disc. One was an optic disc coloboma with a visual field defect and the other had an optic disc pit without a visual field defect. HRT was abnormal only in the eye with optic disc pit with normal fields. While HRT can be a valuable adjunct to disc evaluation and follow-up, it cannot be used in isolation in the differentiation of abnormal from normal optic discs.

Adult↗

PubMed2004

[Hemangioblastoma of the optic nerve growing like a dumbbell through the optic canal: case report].

We report a case of optic nerve hemangioblastoma in a 29-year-old man without a family history of von Hippel-Lindau disease or the other organ symptoms. He had progressive loss of vision and proptosis with a dull pain in his right eye. Magnetic resonance image (MRI) showed a gadolinium (Gd) enhancing solid tumor involving the prechiasmal right optic nerve with intraorbital extension. The tumor contained many signal voids of vessels and grew like a dumbbell through the right optic canal. Digital subtraction angiography demonstrated that the hypervascular tumor was fed by the ophthalmic artery and the orbital ramus of the middle meningeal artery. We succeeded in total resection of this hypervascular tumor by orbito-zygomatic approach. This tumor grew unusually like a dumbbell because it occurred in the optic nerve at the part of the optic canal. Histological examination revealed the tumor to be a characteristic hemangioblastoma. The postoperative course was uneventful. Supratentorial hemangioblastomas, especially optic nerve hemangioblastoma are extremely rare. This paper reviews the previous published cases and discusses their findings.

Adult↗

PubMed1989

Pseudodrusen of the optic disc. Papilledema simulating buried drusen of the optic nerve head.

The distinction between true papilledema and pseudopapilledema rests on characteristics of the optic disc when examined ophthalmoscopically. Buried disc drusen frequently simulate papilledema and often result in misdirected diagnostic maneuvers in search of a cause for presumed intracranial hypertension. When an elevated optic disc exhibits an irregular, "lumpy, bumpy" border, a diagnosis of buried drusen of the optic nerve is usually made. We report a case with papilledema secondary to increased intracranial pressure in which the margins of the swollen optic disc presented this lumpy, bumpy border characteristic of buried drusen. The lumpy character of the disc border disappeared with resolution of the papilledema, and ultrasonography demonstrated the absence of any buried drusen. Other characteristics of papilledema, including extension of the disc swelling into the peripapillary nerve fiber layer, telangiectasia of the superficial vessels of the optic disc, and obscuration of the retinal vessels as they crossed the margins of the optic disc, provided strong evidence of true papilledema and remain the most reliable findings allowing a distinction between true papilledema and pseudopapilledema.

Adult↗

PubMed1986

[Infantile optic glioma involving the whole optic pathway--a case report].

A case of infantile optic glioma involving the whole optic pathway is reported. The patient was a 4-month-old female. The mother noticed that the baby could not follow the object, although her physical development had been apparently normal only until three months after birth. On admission, she was lethargic, although no definite motor weakness was identified. The ophthalmological check revealed delayed bilateral pupillary light reaction and choked disks. Skull X-ray film showed the J-shaped sella and the enlarged bilateral optic canals. CT scan also revealed an isodensity mass in the suprasellar cistern and enlarged bilateral optic nerves. The lesions were enhanced homogeneously with contrast medium and extended toward both optic radiations. Lateral ventricles were mildly dilated. Cerebral angiography showed the upward shift of A1-portion of the bilateral anterior cerebral arteries and the backward shift of the basilar artery. No abnormal vessels were visible. A bifrontal craniotomy was performed to partially remove the suprasellar tumor. The histological diagnosis was optic glioma. The postoperative course was uneventful. The patient was discharged without any neurological deficits except poor visual acuity. Four months later, she suddenly fell into generalized convulsion. CT scan revealed the significant enlargement of residual tumor and ventricular dilatation. Surgical treatment of VP shunt was immediately performed on, and then irradiation of 4,000 rad of total dose to the tumor followed. The tumor size became definitively small. On a follow-up term of 15 months, the patient has been doing well.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Angiography↗

PubMed1977

The histologic basis of optic disk pallor in experimental optic atrophy.

We studied the clinical and microscopic appearances of the optic nerve head in squirrel monkeys with optic nerve degeneration produced by optic nerve transection at the orbital apex. The ophthalmoscopic development of optic disk pallor coincided with the loss of nerve fiber bundles and the rearrangement of the remaining disk astrocytes into dense parallel layers across the nerve head. No astrocytic mitoses were observed and the estimated volume of astrocytes increased only slightly from normal. Among the astrocytes in atrophic disks, many capillaries had patent lumens and ultrastructurally normal endothelial cells. Pallor of the optic disk seems to result from a decrease in the transmission of light into the cytoarchitecture of the atrophic nerve head, not from the absence of capillaries or from extensive astrocytic proliferation.

Animals↗

PubMed2003

Axonal loss after traumatic optic neuropathy documented by optical coherence tomography.

PURPOSE: To report longitudinal retinal nerve fiber layer (RNFL) thickness measurements using optical coherence tomography (OCT) in a patient with traumatic optic neuropathy. DESIGN: Observational case report. METHODS: A 14-year-old boy with severe optic nerve trauma had repeated OCT scans of the peripapillary retinal nerve fiber layer at 3 days, 20 days, 40 days, and 70 days after injury. RESULTS: There was gradual loss of nerve fibers as shown by the OCT color-coded map, RNFL thickness profile, and RNFL thickness measurements around the optic disk. At 70 days of follow-up, severe thinning of the RNFL was observable. CONCLUSIONS: These findings suggest that OCT is able to assess and monitor axonal loss after traumatic optic neuropathy.

Adolescent↗

PubMed1986

Optic disc cupping in arteritic anterior ischemic optic neuropathy resembles glaucomatous cupping.

Five cases of anterior ischemic optic neuropathy secondary to biopsy-proven giant cell arteritis are presented. In each case, cupping of the optic disc, which closely resembled glaucomatous cupping, was observed in the affected eye. The presence of glaucoma was ruled out on the basis of normal intraocular pressures and normal tonographic measurements of facility of outflow. These cases indicate that arteritic ischemic optic neuropathy can result in optic disc cupping, which closely resembles glaucomatous cupping. The similarities in the appearance of cupping of these discs with that seen in eyes with glaucoma suggest that the pathogenesis of cupping in glaucoma and in arteritic ischemic optic neuropathy may share some common mechanisms.

Aged↗

PubMed1999

Diagnostic value of magnetic resonance imaging and planimetric measurement of optic disc size in confirming optic nerve hypoplasia.

PURPOSE: This study set out to evaluate magnetic resonance imaging (MRI) and measurement of optic disc size as diagnostic tools for confirming the diagnosis of optic nerve hypoplasia (ONH) in children with impaired growth. METHODS: MRI was performed to study the size of the intracranial visual pathways, and image analysis measurements of fundus photographs were performed to determine the size of the optic disc. Results from these investigations were compared with those using the gold standard for diagnosis of ONH, which was the clinical eye examination (visual function, ophthalmoscopic signs, or both). Forty children (median age, 9 years; range, 3 to 19 years) with impaired growth were included in the study. RESULTS: The prevalence of ONH among the children was 15%. MRI classification of the visual pathways had a higher positive predictive value than image analysis measurement of the optic disc size (1.0 vs 0.6). CONCLUSIONS: MRI is a good tool for confirming the diagnosis of ONH and may thus facilitate early detection. On the other hand, a small optic disc per se is not a definite indicator of ONH but should encourage further investigation with MRI, especially if there is a clinical suspicion of ONH.

Adolescent↗

PubMed1999

Anterior ischaemic optic neuropathy in a patient with optic disc drusen.

BACKGROUND: Although visual field defects are well-known complications of optic disc drusen, reduction in visual acuity with this condition is rare. METHOD/RESULTS: We report on a 68-year-old male with bilateral optic disc drusen who presented with monocular loss of vision in the right eye associated with an inferior altitudinal visual field defect and signs consistent with acute anterior ischaemic optic neuropathy, confirmed on fluorescein angiography. He also had a left inferior nasal step, but no evidence of glaucomatous cupping. The disc drusen were documented clinically and on B scan ultrasound and computed tomography. CONCLUSIONS: The diagnosis of acute anterior ischaemic optic neuropathy should be considered in patients with optic disc drusen who present with reduced visual acuity, particularly when the visual loss has been acute and non-progressive and is associated with altitudinal field loss and characteristic fluorescein angiography signs.

Aged↗