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Biomedical subjects

Eytan Z Blumenthal

Publications and source records attributed to Eytan Z Blumenthal.

At least 19 recordsLinked to original sources
PubMed2006

Measurement of choroidal melanoma basal diameter by wide-angle digital fundus camera: a comparison with ultrasound measurement.

PURPOSE: To compare the measurement of the basal diameter of choroidal melanoma, an important parameter for planning treatment and as a prognostic factor, by standardized ophthalmic ultrasound versus that obtained using a wide-angle fundus camera. METHODS: The longest and shortest basal diameters of 104 consecutive choroidal melanomas of patients seen at the ocular oncology service of the Hadassah University Hospital were measured by B-scan ultrasound and compared with those measured by a wide-angle fundus camera (Panoret-1000). Each diameter was measured thrice by two ophthalmic photographers, and intra-observer and interobserver reproducibility were calculated as well. RESULTS: The measurements of both the long and short diameters of the choroidal melanomas were significantly larger when measured by Panoret-1000 as compared with the B-scan ultrasound. There was no significant difference among the three measurements of each of the photographers. The interobserver reproducibility between the two photographers was high. CONCLUSIONS: Our findings can be attributed to the larger extent of the pigmentation of the melanoma compared to its recognized elevation. Since pigmentation of choroidal melanoma is easier to recognize than its elevation, we assume that measurement by a wide-angle fundus camera is more accurate in pigmented tumors, and should be adopted for measuring the basal diameter of choroidal melanomas in planning treatment and follow-up.

Choroid Neoplasms↗
PubMed2005

Operator learning effect and interoperator reproducibility of the scanning laser polarimeter with variable corneal compensation.

PURPOSE: To ascertain operator learning effect, and to quantify the interoperator reproducibility, using the newly introduced GDx VCC (variable corneal compensator) scanning laser polarimeter. DESIGN: Prospective instrument validation study. PARTICIPANTS: Three operators with no prior experience in operating the GDx VCC examined one randomly chosen eye of each of 30 randomly ordered subjects (15 glaucoma patients and 15 normal subjects). METHODS: Each study eye was scanned by the 3 operators in a random sequence during a single session. Five GDx parameters were analyzed: TSNIT (temporal, superior, nasal, inferior, temporal) Average, TSNIT Standard Deviation (SD), Superior Average, Inferior Average, and Nerve Fiber Indicator (NFI). MAIN OUTCOME MEASURES: Retinal nerve fiber layer (RNFL) thickness GDx parameters across operators. RESULTS: A learning effect was not found for any of the operators for any of the 5 GDx parameters studied. Reproducibility for each GDx parameter was measured as the mean SD value of the measurements taken by the 3 operators. Interoperator reproducibilities for normal and glaucomatous eyes, respectively, were 0.8 and 1.6 microm (TSNIT Average), 1.7 and 2.2 microm (Superior Average), 1.6 and 2.7 microm (Inferior Average), 1.3 and 1.7 microm (TSNIT SD), and 1.4 and 4.6 microm (NFI). The data obtained by each operator were highly correlated with those of the other 2 operators. CONCLUSIONS: With the commercially available GDx VCC, a learning effect was not found for 3 novice operators. In addition, RNFL measurements seem highly reproducible across operators.

Adult↗
PubMed2004

Dorzolamide-induced choroidal detachment in a surgically untreated eye.

PURPOSE: Choroidal detachment is a known complication of topical hypotensive agents when used to treat eyes sensitized by prior surgery. We document the abrupt development of an extensive choroidal detachment after initiation of dorzolamide therapy in a surgically untreated eye with primary open-angle glaucoma. DESIGN: Observational case report. METHODS: A 76-year-old woman with primary open-angle glaucoma and no history of ocular surgery developed a choroidal detachment 12 hours after initiation of therapy with dorzolamide eye drops. Choroidal detachment was diagnosed clinically and confirmed by echography. RESULTS: Withdrawal of the drug and initiation of corticosteroid drops resulted in prompt resolution of the choroidal detachment. CONCLUSIONS: Choroidal detachment can occur in surgically untreated eyes after use of a topical carbonic anhydrase inhibitor.

Aged↗
PubMed2004

Patterns of glaucomatous visual field progression identified by three progression criteria.

PURPOSE: To determine typical patterns of repeatable glaucomatous visual field progression. DESIGN: Retrospective analysis of data obtained from two prospective studies. METHODS: Included were 72 eyes of 72 patients tested up to six times over 2 years, and 40 eyes of 40 patients followed annually for up to 12 years. Each patient had two abnormal baseline visual fields, abnormal optic nerves, and serial fields. Progression was identified using three methods: by glaucoma change probability using total deviation (GCP-TD) and pattern deviation (GCP-PD) plots and by a clinical criteria. Progression was categorized as deepening or expansion of an existing scotoma, or a new scotoma. RESULTS: The percentage of eyes repeatably progressed ranged from 17% to 27%. The most common pattern of progression was a deepening of an existing scotoma in the annual group, followed by expansion. With two follow-ups required, percentages for deepening only were 20% (clinical classifier). A combination of expansion and deepening was most common for the GCP criteria: 15% (GCP-TD classifier), and 10% (GCP-PD classifier) for the annual group. For the semiannual group, deepening was most common with the clinical criteria (11% of eyes), and deepening with expansion was most common by GCP criteria (14%, GCP-TD and GCP-PD). No eyes showed repeatable new scotomas. CONCLUSIONS: Glaucomatous visual fields progress in the area of the visual field where baseline testing showed an existing scotoma. Follow-up testing might be improved by concentrating on already defective locations and using sparser test patterns or screening algorithms in normal areas of the visual field.

Diagnostic Techniques, Ophthalmological↗
PubMed2004

A two-compartment model of the human retina.

PURPOSE: In this article we question a basic concept in retinal pathology, which views the retina as composed primarily of neural elements, in a single compartment. METHODS: We suggest an alternative approach, centering on the epithelial-glial elements of the retina, dividing the retina into two distinct compartments. The framework of these two compartments is composed of two epithelial-like monostratified cell layers facing each other by their apical surfaces. This model is in agreement with the embryological development of the retina. RESULTS: Each compartment is composed of a monostratified cell layer in which neural elements are embedded and each is supplied by a different blood supply. The inner compartment, also referred to as the Muller cell compartment, extends between the inner and outer limiting membranes. The outer, or RPE, compartment extends between the outer limiting and Bruch's membranes. The border between the two compartments is formed by the outer limiting membrane (OLM). One simplified example utilizing the two-compartment concept is as follows: inner compartment edema (inner blood-retinal barrier breakdown) may manifest as cystoid edema, but not as serous retinal detachment, while outer compartment edema (outer blood-retinal barrier breakdown) may manifest as serous retinal detachment but not as cystoid edema, as long as the integrity of the OLM is maintained. CONCLUSION: A two-compartment approach to the structure of the retina, centering on non-neural elements, may enhance our understanding of some retinal pathologies. Various retinal diseases, mainly of vascular origin, are limited to one of the two compartments.

Animals↗
PubMed2004

The reliability of frequency-doubling perimetry in young children.

OBJECTIVE: To evaluate whether healthy young children are able to perform automated static perimetry reliably using the frequency-doubling technology (FDT) perimeter. DESIGN: Prospective, observational case series. PARTICIPANTS: Forty healthy children aged 4 to 14 years. TESTING: Subjects underwent, in 1 randomly chosen eye, 2 consecutive visual field (VF) tests using the C-20 full-threshold program of the commercially available FDT. MAIN OUTCOME MEASURES: Global measures included mean deviation (MD), pattern standard deviation (PSD), test duration and reliability indices, including fixation losses and false-positive and false-negative errors. Fixation losses are checked 6 times throughout the examination, rather than being continuously monitored. Two scoring systems, based on the total deviation probability plot, classified each VF as normal or abnormal. RESULTS: All subjects completed the VF test. The better of 2 examinations (as determined by the MD score) was used for analysis. The average test duration was 4.9+/-0.7 minutes for the entire group. The mean MD and PSD were -0.78+/-4.9 and 6.7+/-6.2, respectively. A clear correlation to age was found for MD, PSD, abnormality of the VF, and test duration (all P<0.05). Of all VFs, 32.5% were unreliable, such that at younger than 8 years of age, 42.9% of the VFs were unreliable, compared with 23.1% for those older than 8 years. Younger than 8 years of age, 78.6% of VFs were abnormal, whereas for ages 8 years and older, 26.9% of VFs were abnormal. CONCLUSIONS: Frequency-doubling technology seems to be a clinically feasible VF method for evaluating young children older than approximately 8 years of age. The reliability indices, MD, test duration, and the reproducibility of the VF test were found to be highly correlated with age, in such a way that these parameters all improved with increasing age.

Adolescent↗
PubMed2004

Using unsupervised learning with variational bayesian mixture of factor analysis to identify patterns of glaucomatous visual field defects.

PURPOSE: To determine whether an unsupervised machine learning classifier can identify patterns of visual field loss in standard visual fields consistent with typical patterns learned by decades of human experience. METHODS: Standard perimetry thresholds for 52 locations plus age from one eye of each of 156 patients with glaucomatous optic neuropathy (GON) and 189 eyes of healthy subjects were clustered with an unsupervised machine classifier, variational Bayesian mixture of factor analysis (vbMFA). RESULTS: The vbMFA formed five distinct clusters. Cluster 5 held 186 of 189 fields from normal eyes plus 46 from eyes with GON. These fields were then judged within normal limits by several traditional methods. Each of the other four clusters could be described by the pattern of loss found within it. Cluster 1 (71 GON + 3 normal optic discs) included early, localized defects. A purely diffuse component was rare. Cluster 2 (26 GON) exhibited primarily deep superior hemifield defects, and cluster 3 (10 GON) held deep inferior hemifield defects only or in combination with lesser superior field defects. Cluster 4 (6 GON) showed deep defects in both hemifields. In other words, visual fields within a given cluster had similar patterns of loss that differed from the predominant pattern found in other clusters. The classifier separated the data based solely on the patterns of loss within the fields, without being guided by the diagnosis, placing 98.4% of the healthy eyes within the same cluster and spreading 70.5% of the eyes with GON across the other four clusters, in good agreement with a glaucoma expert and pattern standard deviation. CONCLUSIONS: Without training-based diagnosis (unsupervised learning), the vbMFA identified four important patterns of field loss in eyes with GON in a manner consistent with years of clinical experience.

Algorithms↗
PubMed2004

Quantifying retinal nerve fiber layer thickness histologically: a novel approach to sectioning of the retina.

PURPOSE: To present a technique of ocular sectioning that enables continuous histologic measurements of peripapillary retinal nerve fiber layer (RNFL) thickness in a concentric ring around the optic disc, corresponding to similar regions measured by in vivo imaging techniques. METHODS: Two pig eyes and two normal human eyes were processed using the "umbrella" technique, in which peripapillary concentric ring sections were obtained, at increasing diameters, all centered on the optic disc. Each histologic ring section contains a continuous circumferential 360 degrees retinal slice, oriented approximately perpendicular to the retinal surface. Every histologic slice contains each axon of the retina, sectioned perpendicular to each axon's long axis and at an equal set distance from the disc margin. RESULTS: Ring sections from pig and human eyes are presented and correlated to known RNFL anatomy. For the two human eyes, peripapillary RNFL thickness was quantified and plotted, resulting in the expected double-hump pattern. CONCLUSIONS: The umbrella technique provides, on a single histologic section, all necessary information for quantifying the entire RNFL layer of that eye, in a standardized fashion. This technique can simplify the process of analyzing the RNFL thickness histologically, assist in obtaining a normative database of RNFL thickness in humans, and be implemented as a histologic end point in animal studies evaluating new treatment modalities for glaucoma.

Animals↗
PubMed2003

Misleading statistical calculations in far-advanced glaucomatous visual field loss.

OBJECTIVE: In this study, the capability of statistical analysis indices to characterize static automated visual fields (VFs) accurately in cases of far-advanced glaucoma was assessed. DESIGN: Retrospective observational case series. PARTICIPANTS: Sixteen eyes of 15 patients with end-stage glaucoma and evidence of collapse of VF statistical analysis indices were included in the study. METHODS: End-stage glaucoma was defined as vertical cup-to-disc ratio of 0.9 or more, mean deviation less than -24 dB and with only a central or temporal island remaining in the VF gray scale. Collapse of statistical indices was defined as any of the following: pattern deviation probability plot without a single VF location showing P < 0.5%; corrected pattern standard deviation (CPSD) and pattern standard deviation (PSD) probability less than 5% or within normal limits (WNL); short-term fluctuation (SF) probability WNL; glaucoma hemifield test (GHT) not outside normal limits (ONL); or presence of a low patient reliability comment triggered by 40% or more false-negative (FN) responses. MAIN OUTCOME MEASURES: Visual field statistical indices. RESULTS: Of the 16 VFs showing misleading statistical calculations, 9 of 16 eyes had a normal pattern deviation probability plot. The PSD, SF, and CPSD parameters were normal or barely outside the normal range in 4 of 16, 10 of 16, and 5 of 16 eyes, respectively. The GHT was ONL in 7 of 13 eyes, borderline with generalized reduction of sensitivity (GRS) in three eyes, and only GRS in two additional eyes. Low patient reliability was triggered because of an FN score of 40% or more in 10 of 16 eyes. CONCLUSIONS: Statistical indices are crucial for the interpretation of automated static VFs. However, in end-stage glaucomatous VF loss, both summary statistical indices and reliability indices may not detect abnormality, thus misleading the casual observer.

Data Interpretation, Statistical↗
PubMed2003

Evaluating several sources of variability for standard and SWAP visual fields in glaucoma patients, suspects, and normals.

PURPOSE: To quantify factors affecting test-retest variability of threshold measurements over a series of 3 serial visual fields (VF). DESIGN: Prospective comparative observational study. PARTICIPANTS: Forty-one normals, 10 suspects and 35 stable glaucoma patients. METHODS: All subjects performed 3 standard and 3 short-wavelength automated perimetry (SWAP) VFs. At each VF location, severity (defined as age-corrected total deviation) and test-retest variability (TRV), defined as the standard deviation of 3 serial threshold values, were calculated. A multiple regression model (constructed separately for standard VF and SWAP) incorporated 13 factors: severity, location, eccentricity, study group, diagnosis, superior versus inferior hemifield, nasal versus temporal hemifield, one-versus-two thresholds, age, mean pupil size, pupil size variability, between-subject variation, and residual variation. MAIN OUTCOME MEASURES: Variability in threshold sensitivity VF values. RESULTS: Mean TRV (+/- standard deviation) for normal, suspect and glaucoma eyes, respectively, was: 1.28 +/- 0.87, 1.53 +/- 1.04 and 2.20 +/- 1.79 dB for standard VF, and 1.87 +/- 1.35, 1.86 +/- 1.24 and 2.68 +/- 1.85 dB for SWAP. The contribution of each factor to the model for standard VF and SWAP (SWAP in parentheses) were: severity 15.5% (6.9%); location 2.7% (4.1%); eccentricity 1.1% (0.64%); diagnosis 2.9% (5.9%); "superior versus inferior" hemifield 0.17% (1.7%); "nasal versus temporal" hemifield 0.06% (0.02%); one-versus-two thresholds 0.04% (0.16%); age 0.1% (0.06%); mean pupil size 0.59% (0.1%); pupil size variability 3.2% (2.8%); between-subject 8.0% (13.5%) and residual variation 61.0% (66.6%). Excluding between-subject and residual variation, the 11-factor model was able to account for less than one third of the variability seen in both standard VF and SWAP. CONCLUSIONS: Severity of defect and between subject variation exerted the largest effect on TRV. However, even if all 11 factors could be adjusted for, it would reduce the magnitude of TRV by only 30%. More work is needed to reduce the remaining variability inherent in psychophysical testing and to better understand the intrinsic physiological variability present both in healthy and diseased eyes. It is possible that a larger number of VFs used for the calculation of TRV might further reduce the magnitude of the remaining variability found in this study.

Adult↗
PubMed2003

Bridging analog and digital video in the surgical setting.

Editing surgical videos requires a basic understanding of key technical issues, especially when transforming from analog to digital media. These issues include an understanding of compression-decompression (eg, MPEGs), generation quality loss, video formats, and compression ratios. We introduce basic terminology and concepts related to analog and digital video, emphasizing the process of converting analog video to digital files. The choice of hardware, software, and formats is discussed, including advantages and drawbacks. Last, we provide an inexpensive hardware-software solution.

Analog-Digital Conversion↗
PubMed2003

[Steroid induced glaucoma].

Steroid treatment has gained notoriety due to its tendency to induce multiple side effects, including a variety of ocular side effects. Administration of local, regional, inhalation or systemic steroids may induce the development of ocular hypertension, which might even result in subsequent open angle glaucoma. About one in every three people is considered a potential "steroid responder". A significant elevation of intraocular pressure might result in these patients in response to steroid treatment. Included in this group are patients with first degree relatives suffering from open angle glaucoma. Morphologic changes in the trabecular meshwork (which serves as the site of aqueous humor drainage from the eye) are suggested as the proposed mechanism through which steroid treatment results in glaucoma. Steroids are said to induce the expression of a gene that is located on chromosome 1 and is known as TIGR or GLCIA. its product is a protein called myocilin. Ocular hypertension secondary to steroid treatment is usually reversible, when treatment is limited to a period of less than 12 months. The fear of ocular hypertension, which is usually unnoticed by the patient, obligates regular ophthalmologic follow-up examinations, including tonometry, visual fields and optic disc examinations.

Chromosome Mapping↗
PubMed2002

Infrequent confirmation of visual field progression.

OBJECTIVE: To evaluate the effects of the repeatability criteria on the detection of change in visual fields by six progression algorithms used in standard automated perimetry. DESIGN: Retrospective, observational case series PARTICIPANTS: Fifty-one glaucoma patients, each with multiple visual fields performed between May 1990 and December 1998, were included. METHODS: Each patient's set of visual fields were analyzed using the glaucoma change probability, the Early Manifest Glaucoma Trial (EMGT) algorithm, a modified glaucoma change probability score, a modified EMGT score, the Advanced Glaucoma Intervention Study algorithm, and the Collaborative Initial Glaucoma Treatment Study algorithm. MAIN OUTCOME MEASURES: The effects of repeatability on the detection of field change, the level of agreement among algorithms, as well as the number of eyes identified as changed with each algorithm, were assessed. RESULTS: Mean follow-up was 34 months (range, 12-87 months). The average percentage of eyes with change based on three consecutive follow-up fields was 8.2% (4.0%-12.5%). However, of those showing change on the initial follow-up, this change from baseline was observed in subsequent examinations on average in 23% (18%-33%), depending on the algorithm. When change was based on just one field, four of the six algorithms noted a significantly greater number of eyes with change. The algorithms, however, did not differ significantly when confirmation of field change required two versus three consecutive follow-up visual fields. CONCLUSIONS: Although current algorithms may help identify change, there are inconsistencies among them. We found that requiring repeatable change from baseline significantly reduces the number of changed eyes identified with each subsequent follow-up field. Identification and confirmation of change in visual fields plays an important role in helping to identify true glaucoma progression; however, the specific methods to do so have yet to be determined.

Adult↗
PubMed2002

Changes in ultrasound findings in posterior uveal melanoma after Ruthenium 106 brachytherapy.

PURPOSE: To analyze the postbrachytherapy ultrasonographic dynamics of uveal melanoma tumor height and internal reflectivity. DESIGN: Prospective, comparative, observational case series. PARTICIPANTS: One hundred forty-seven patients (147 eyes) with posterior uveal melanoma having a mean age of 61 years (range, 29-97 years) who were treated with Ruthenium 106 brachytherapy. METHODS: Patients were followed-up with ultrasonography using both A and B modes of standardized echography every 6.7 +/- 0.3 months (mean +/- standard error of the mean) for a total of 1001 ultrasound examinations. On average, each patient was examined 5.8 times (range, 3-17 times). The echographic parameters included tumor base size, height, internal reflectivity, regularity, vascularity, and extra-scleral extension. To compare the response of tumors of different sizes, each tumor was standardized to its initial size at brachytherapy. MAIN OUTCOME MEASURES: The dynamics of the tumor height and internal reflectivity. RESULTS: At the time of brachytherapy, the mean height of the tumors was 5.2 mm (range, 2.2-11.8 mm). After brachytherapy, 142 tumors (96.6%) responded by a decrease in height. The decrease in height was at an initial rate of approximately 3% per month. Most of the tumors did not regress entirely; rather, their height stabilized on a constant value (on average 61% of the initial height) after approximately 18 to 24 months. The decrease in height after brachytherapy was best fitted by the sum of a first order exponential decay and a constant (h = 61 + 35*e(-0.12t), in which t = time in months). The half-life of the decay was 5.8 months. Large tumors (>8 mm) had a faster initial decrease in height, and stabilized on a lower percentage of their initial height (50%) compared with small tumors (70%). Thus, the half-life of the height exponential decay was 5.3 months for small tumors (2-4 mm) and 3.3 months for the large tumors (>8 mm). Internal reflectivity increased from a mean of 40% before therapy to 70% after 2 years. The dynamics of the reflectivity were best fitted with the function: f = 45 + 24(1-e(-0.09t)). Larger tumors, which initially had lower internal reflectivity, presented with a slower increase in internal reflectivity (t() = 8.7 months) compared with smaller tumors (t(1/2) = 5 months). CONCLUSIONS: The postbrachytherapy ultrasonographic dynamics of uveal melanomas resemble a function composed of the sum of a constant and a first order exponent, suggesting the possible existence of two components (cell populations), one unaffected by brachytherapy and the other a radiosensitive population that reacts to brachytherapy in an exponential decay. An exponential decay can imply that the postbrachytherapy death of each tumor cell is a stochastic Markovian process that is independent of the death of other tumor cells.

Adult↗
PubMed2002

The learning effect in visual field testing of healthy subjects using frequency doubling technology.

PURPOSE: To evaluate the presence, duration and magnitude of a learning effect in serial visual field (VF) testing, using the commercially available frequency doubling technology (FDT) instrument. PATIENTS AND METHODS: 21 healthy adults with no prior VF experience underwent 6 serial VF tests, using the full-threshold C-20 program of the Zeiss-Humphrey FDT analyzer, on one randomly chosen eye. Tests were spaced at least two days apart. RESULTS: The average mean sensitivity was 32.37 +/- 2.6 dB; the average mean deviation (MD) was 1.22 +/- 1.8 dB. The MD at the first examination (0.28 +/- 2.1 dB) was significantly poorer than at any of the other testing sessions (p<0.003). Similarly, the mean sensitivity at the first examination (31.16 +/- 3.0 dB) was significantly lower than any other testing session (p<0.004). The proportion of improvement from the first to the second session was 63% and 65% of the total improvement, for mean sensitivity and MD, respectively. Mean test duration showed a modest reduction, from 4.40 +/- 0.3 minutes in the first session to 4.17 +/- 0.4 minutes in the last session (p = 0.023). A sub-analysis comparison of the different VF segments showed a more prominent learning effect in the peripheral and nasal visual segments (p<0.0001). CONCLUSION: Baseline measurements should best rely on the second testing session, since MD and mean sensitivity are somewhat poorer when subjects with no prior VF experience are first tested on the FDT instrument. This may be especially true for the purpose of following patients over time.

Adult↗