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Biomedical subjects

M Iester

Publications and source records attributed to M Iester.

At least 19 recordsLinked to original sources
PubMed2006

Corneal thickness and visual field damage in glaucoma patients.

PURPOSE: To verify whether there was a significant correlation between central corneal thickness (CCT) and visual field damage in patients with primary open angle glaucoma (POAG). METHODS: A total of 99 eyes with POAG were consecutively recruited. Patients were classified as glaucomatous based on visual field and optic nerve head damage. All underwent applanation tonometry, Humphrey perimetry, and measurement of CCT with ultrasonic pachymetry. Based on CCT value, the sample was split at the mode in two groups (group 1<535 microm, n=49; group 2>or=535 microm, n=50). RESULTS: Entire cohort: mean CCT 554 microm+/-45.03; mean deviation (MD) -6.68 dB+/-7.32; pattern standard deviation (PSD) 5.33+/-3.75; intraocular pressure (IOP) 17.91+/-4.16 mmHg with treatment. Group 1: CCT was 504.8 microm+/-30.8; MD -9.01 dB+/-8.72; PSD 6.38+/-3.99; IOP 18.02 mmHg+/-4.66. Group 2: mean CCT 574.6 microm+/-35.03; MD -4.39 dB+/-4.70; PSD 4.25+/-3.19; IOP 17.79 mmHg+/-3.57. A significant difference was found between the two groups for both MD and PSD. Linear regression analysis showed a significant correlation between CCT and PSD (P<0.001). CONCLUSIONS: Our data show that patients with a thinner cornea had a worse MD and PSD. As a thinner CCT causes an underestimation of the true IOP, there may be a delay in the diagnosis of POAG or an inadequate estimate of the clinical course despite apparently desirable IOP applanation readings.

Adult↗
PubMed2006

Detection of glaucomatous optic nerve head by using Heidelberg topographic maps.

PURPOSE: To evaluate the capacity of a new topographic map analysis to detect abnormal optic discs from healthy ones in a new cohort of subjects. PATIENTS AND METHODS: Only one eye was chosen randomly from each subject included in the study. In total, 20 normal eyes with a normal visual field, an IOP of <22 mmHg and no history of glaucoma in their family, and 20 glaucomatous eyes with an abnormal visual field and an open angle were selected. All the subjects were examined with the Heidelberg Retina Tomograph (HRT, Heidelberg Engineering GMBH, Heidelberg, Germany) and Humphrey Perimeter, program 30-2 (Humphrey Instrument, Inc., San Leandro, CA, USA). Topographic maps analysis was performed to each HRT optic nerve head image. Sensitivity, specificity, and diagnostic precision were calculated. RESULTS: When the topographic map analysis was applied to the group, a sensitivity of 80%, a specificity of 75%, and a diagnostic precision of 77.5% were obtained. CONCLUSION: Using the topographic map analysis, the HRT capacity to differentiate normal optic discs from those with glaucoma was similar to those already published in the literature, but using this technique there is no input from the observer to draw the contourline and reference plane is not necessary.

Aged↗
PubMed2005

Observer interpretation variability of peripapillary flow using the Heidelberg Retina Flowmeter.

PURPOSE: To evaluate the intraobserver and interobserver reproducibility of the automatic full field perfusion image analysis (AFFPIA) program on Heidelberg Retina Flowmeter (HRF) derived perfusion images in a multicentre study group. METHODS: A total of 10 subjects were consecutively recruited in the study. One eye was randomly selected for each patient. Blood flow was assessed by HRF and flow measurements were analyzed by using the AFFPIA program. AFFPIA calculates the Doppler frequency shift and the haemodynamic variables: flow for each pixel. Intraobserver and interobserver reproducibility was calculated for AFFPIA program. The retinal blood flow was calculated in the superior and inferior section, furthermore, each section was divided into three parts: the temporal area, the nasal, and the rim area, as for software, but only the temporal and nasal areas were considered in this study. The blood flow and the area considered were evaluated for each part. RESULTS: When the intraobserver and intraimage reproducibility was studied, the coefficient of variation ranged from 0.4 to 1.9%. When the interobserver and intraimage reproducibility was studied, the retinal blood flow coefficient of variation ranged from 0.52 to 3.30% for the supero-temporal area, from 0.13 to 2.67% for the inferotemporal area, from 0.15 to 2.75% for the supero-nasal area, and from 0.04 to 5.65% for the infero-nasal area. CONCLUSION: Our results with AFFPIA showed an interobserver coefficient of variation of retinal blood flow measurements always less than 6% in both temporal and nasal areas. No significant difference was found among the four observers for the flow measurements.

Adult↗
PubMed2002

Quality of life in patients with early, moderate and advanced glaucoma.

PURPOSE: To evaluate the quality of life in glaucomatous patients using two different questionnaires: the medical outcomes study 36-item short-form health survey (MOS SF-36) and Viswanathan et al's questionnaire and to compare these two questionnaires. METHODS: Seventy-seven patients with glaucoma were consecutively selected. Two force-choice questionnaires were administered to each patient. Viswanathan et al's questionnaire was related to visual disability and the second was related to the quality of life from the MOS 36-item short-form health survey. Both questionnaires were evaluated among all the considered patients and the results were compared. Then the questionnaire which did the best evaluation was used to test the quality of life in three different subgroups based on the mean deviation of the worse eye. Mann-Whitney non parametric test and Spearman's r coefficient were used and a P value less than 0.05 was considered to be statistically significant. A linear regression model was used. RESULTS: In the entire group (n = 77) the Mean Deviation (MD) was -6.5 +/- 6.8 dB (mean +/- standard deviation) and Corrected Pattern Standard Deviation (CPSD) was 4.7 +/- 4.1 dB. The score of the Viswanathan et al's questionnaire was 8.3 +/- 2.4, while MOS SF-36 score ranged from 60.5% to 100% (mean score %). A significant (P < 0.0001) correlation was found between the score of the Viswanathan et al's questionnaire and MD (r = 0.79), Pattern Standard Deviation (PSD) (r = -0.68) and CPSD (r = -0.61). CONCLUSION: Viswanathan et al's questionnaire was more useful than MOS SF-36, both for the score and for the velocity to use. Furthermore Viswanathan et al's questionnaire was more significantly correlated to visual field MD.

Activities of Daily Living↗
PubMed2001

Three-dimensional optic nerve head algorithm for the detection of glaucomatous damage.

PURPOSE: To determine whether a three-dimensional optic disc algorithm could be useful in differentiating optic nerve heads (ONH) with a normal visual field from those with an abnormal visual field also when using a simultaneous stereoscopic computerised ONH analyser. METHODS: One eye was randomly chosen from 45 normals and 55 patients with glaucoma (mean deviation -7.7 +/- 9.0 dB, corrected pattern standard deviation 3.1 +/- 2.3 dB). All the subjects were examined with the Humphrey Perimeter (program 30-2) and with the Topcon Image-net X Rev-3.51 b. Using the topographic map of the system, the algorithm of the third moment or cup shape measure was applied to the numbers (the number of points ranged from 623 to 1,883 depending on the size of the disc area) that identify the heights of all the points of the optic disc surface. Findings were analysed by means of the Mann-Whitney U test and receiver operator characteristic curves. RESULTS: The sensitivity and specificity of this three-dimensional ONH algorithm applied to Topcon Image-net was 90.6% and 85.1% respectively. No difference was found between the groups for age, disc area and number of the analysed points. CONCLUSIONS: The algorithm of cup shape measure or third moment is a useful parameter to separate eyes with normal from those with abnormal visual field also when using a simultaneous stereoscopic system such as Image-net.

Algorithms↗
PubMed2001

Interobserver variability of optic disk variables measured by confocal scanning laser tomography.

PURPOSE: To assess the interobserver variation of confocal laser scanning tomographic measurements of the optic nerve head and to address the question of whether the addition of clinical optic disk photographs is helpful in outlining the optic disk margin and in reducing the observer-related variation of the measurements. PATIENTS AND METHODS: Optic disk variables for 16 eyes of 16 patients with glaucoma, generated by confocal laser scanning laser tomography (Heidelberg Retina Tomograph), were independently evaluated by four experienced glaucoma specialists, and the interobserver variability was calculated. A second separate review by the same observers included the use of clinical stereoscopic color optic nerve head photographs to aid definition of the optic disk margin. RESULTS: Optic disk parameters with the smallest interobserver variation were cup shape measure, maximum cup depth, height variation contour, and mean height contour. The intraobserver variation of these parameters did not increase when clinical optic disk slides were additionally available. Parameters with the highest interobserver variation were volume below surface, volume below reference, volume above surface, and volume above reference. The observer variation of these optic disk parameters increased significantly for two of the four examiners when clinical optic disk slides were additionally available for outlining the optic disk margin. CONCLUSION: Confocal laser scanning tomography of the optic nerve head can be improved significantly if clinical optic disk photographs are additionally available to help in outlining the optic disk margin. Because interobserver variation in the tomographic optic disk measurements can be significant, even if experienced observer are involved, tomographic optic disk measurements may be centralized in reading centers in the case of multicenter studies.

Diagnostic Techniques, Ophthalmological↗
PubMed2001

Clinical ability of Heidelberg retinal tomograph examination to detect glaucomatous visual field changes.

PURPOSE: To determine the agreement between Heidelberg Retinal Tomograph (HRT; Heidelberg Instruments, Heidelberg, Germany) and visual field examinations in differentiating normal from glaucomatous eyes and to evaluate the sensitivity and specificity of HRT optic disc examination in detecting eyes with glaucomatous damage. STUDY DESIGN: Cross-sectional study. PARTICIPANTS: Three hundred fifty-nine patients, for a total of 359 eyes (55 normal, 209 with ocular hypertension [OHT], and 95 with primary open-angle glaucoma). INTERVENTION: Optic disc imaging by HRT, using a 10 degrees angle view; a mean of three repeated images were analyzed using version 2.01 software. The optic disc was classified as "normal/glaucomatous" on the basis of multivariate discriminant analysis and cumulative frequency distribution (ranked-segment distribution curves). The visual field was examined using the DS 30 II program (Humphrey perimeter, Zeiss Humphrey System, Dublin, CA), with a glaucomatous visual field being defined on the basis of an abnormal glaucoma hemifield test and a statistically significant corrected pattern standard deviation less than 4 dB. MAIN OUTCOME MEASURES: Agreement between HRT and visual field examinations calculated by means of the kappa statistic and the sensitivity and specificity of HRT examination. RESULTS: The agreement between the visual field-based and HRT definition of glaucoma was fair to poor, with a kappa statistic of between 0.48 and 0.28. The sensitivity and specificity of the HRT examination were, respectively, 80% and 65%, according to Mikelberg's analysis, and, respectively, 31% to 53% and 90% to 92%, according to the analysis based on cumulative curves of normality. CONCLUSIONS: In a broad clinical setting including normal, OHT, and glaucoma patients, the HRT and visual field tests have fair to poor agreement in detecting glaucoma. The HRT demonstrated a lack of specificity when using Mikelberg's multivariate discriminant analysis and a lack of sensitivity when using cumulative frequency distribution (ranked-segment distribution) curves. These values did not change when normal or OHT patients were excluded from the analysis. In the clinical setting, caution should be used when interpreting HRT results on the basis of multivariate discriminant analysis or cumulative frequency distribution curves.

Adult↗
PubMed2001

New Tonopen XL: comparison with the Goldmann tonometer.

PURPOSE: To compare the intraocular pressure (IOP) values obtained using a Goldmann tonometer (Haag-Streit) with those obtained with the new Tonopen XL (Mentor), which has certain differences compared with first- and second-generation models. METHODS: The IOPs of 104 patients were assessed by Goldmann tonometer and Tonopen XL tonometer. Goldmann measurements was done first in 145 eyes and Tonopen measurements were done first in 53 eyes. Four observers measured the IOP. Observers A, B and C used the Goldmann tonometer first and then the Tonopen XL, while observer D used the Tonopen XL first and then the Goldmann tonometer. The results were analysed by descriptive analysis and, when the distribution of the data was normal, paired t-test and Pearson's r coefficient were used to compare and correlate IOP measurements between Goldmann and Tonopen measurements. When the distribution of the data was non-normal, the Wilcoxon matched-pair test and Spearman coefficient were used. The agreement between Goldmann and Tonopen values was also calculated. ANOVA test was used to compare the difference obtained by 'Goldmann minus Tonopen' measurements among the three different observers. RESULTS: A statistically significant difference (p < 0.0001) was found between the IOP readings obtained by Goldmann tonometer and the Tonopen XL and a significant correlation was found between the Goldmann values and Tonopen XL values (p < 0.001). When the Goldmann IOP was more than 20 mmHg the Tonopen XL measurements were lower than the Goldmann values. Also in this group this difference was statistically significant. No significant difference was found between Goldmann values and Tonopen values among the three observers, even though a significant difference was found between Goldmann values and Tonopen values for observer B. When the values obtained by first the Goldmann tonometer and then the Tonopen XL were compared with those obtained by first the Tonopen XL and then the Goldmann tonometer, no significant difference was found between the two groups. CONCLUSION: The new Tonopen XL provides similar results to the Goldmann tomometer in 62% of the cases and was slightly less accurate than the Goldmann tonometer for extreme values, just like the previous Tonopen. Nevertheless the precision is good enough for the purpose of adequate screening.

Analysis of Variance↗
PubMed2001

Retinal nerve fiber layer and physiological central corneal thickness.

PURPOSE: To determine the relationship between central corneal thickness and the measurement of retinal nerve fiber layer thickness around the optic nerve head using a confocal scanning laser polarimeter such as the Nerve Fiber Analyzer (GDx). METHODS: Forty-four eyes were recruited for this study. Each patient had a normal visual field and a healthy optic nerve head, which was assessed by slit-lamp biomicroscopy with a 90-diopter lens and by a scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Using the GDx, retinal nerve fiber layer thickness was calculated from 1.75 disc diameters together with some standard GDx parameters, including the number, symmetry, superior ratio, inferior ratio, maximum modulation, and ellipse modulation. Corneal thickness was measured with the DGH-1000 ultrasonic pachymeter. Descriptive analysis was used and Pearson's r coefficient of correlation was calculated. RESULTS: Corneal thickness was not significantly correlated to retinal nerve fiber layer thickness, but it was significantly (P < 0.05) correlated to the other GDx parameters. CONCLUSION: From these data. peripapillary retinal nerve fiber layer thickness is shown not to be significantly correlated to the corneal thickness, even if for the standard GDx parameters a significant correlation was found.

Aged↗
PubMed2001

Normal retinal nerve fiber layer thickness in the peripapillary region measured by scanning laser polarimetry.

PURPOSE: To measure retinal nerve fiber layer thickness (RNFLT) as a function of distance from the optic nerve head using a confocal scanning laser polarimeter, such as the Nerve Fiber Analyzer (GDx). METHODS: Twenty eyes of 20 healthy patients were recruited for this study. Each patient had a normal visual field and a healthy optic nerve head, which was assessed by slit-lamp biomicroscopy using a 90-diopter lens and by a scanning laser ophthalmoscope. Using the GDx, RNFLT was calculated from 1.1 disc diameters (DD) to 2.5 DD in 0.1-DD increments from the outer edge of the optic disc rim. RNFLT was successively evaluated for the entire annulus surface, for each quadrant, and for every 10 degree sector. RNFLT was calculated in retardation degrees. Differences in RNFLT were calculated by analysis of variance. RESULTS: When the entire RNFLT was considered, the measurements close to the optic nerve head (at 1.1 and 1.2 DD) were found to be significantly (0.05 < or = P < or = 0.01) different from those measured far from the disc (at 2.4 and 2.5 DD). The inferior quadrant had the greatest RNFLT followed by the superior quadrant. When RNFLT was analyzed for every 10 degrees, RNFLT at 1.1 and 1.2 DD was significantly (P < or = 0.001) different from that measured at 2.4 and 2.5 DD in almost all 36 sectors. In the 36 considered sectors, no significant difference was found for all the RNFLT values that were calculated in all the positions of the annulus surface between 1.1 and 1.7 DD. CONCLUSION: From these data, peripapillary RNFLT is shown to be significantly (P < or = 0.001) thinner in the periphery (2.5 DD) than around the optic disc (1.1 DD). However, the lack of any difference in RNFLT from 1.1 to 1.7 DD suggested that the mild variations to locate the optic disc contour line do not change the results of the analysis if the RNFLT is calculated within 1.8 DD.

Aged↗
PubMed2001

Survival analysis for success of Molteno tube implants.

AIM: To apply survival analysis in assessing the long term outcome of Molteno tube implantation and to identify risk factors for failure. METHODS: A retrospective, 10 year, consecutive case series study of 119 eyes that underwent implantation of a Molteno tube. The main outcome measures considered were intraocular pressure (IOP), visual acuity, and complications. RESULTS: A 30% or greater reduction in IOP was achieved in 68.9% of cases. However, the overall, "complete success" rate (IOP <22 mm Hg with no medications) after a mean (SD) follow up period of 43 (33) months (range 6-120) was only 33.6% despite a fall in mean (SD) IOP from 38.2 (8.2) mm Hg to 20.1 (11.0) mm Hg. The "qualified success" rate (IOP <22 mm Hg with or without medications) was 60.5%. Failure was most common in the first postoperative year but could occur after several years, the survival curve having an exponential shape. The only statistically significant risk factor for failure identified was pseudophakia, although eyes with neovascular glaucoma tended to fare poorly. Postoperative IOP tended to be lower after double plate than after single plate implantation. There was no significant difference in outcome based on age, sex, race, previous penetrating keratoplasty, or previous conjunctival surgery. CONCLUSIONS: In eyes at high risk of trabeculectomy failure, implantation of an aqueous shunt device should be considered. Pseudophakia should be considered an additional risk factor for failure. Early failure appeared relatively more common but long term follow up of all cases is recommended to ensure adequate management of late failures.

Adult↗
PubMed2000

Learning effect, short-term fluctuation, and long-term fluctuation in frequency doubling technique.

PURPOSE: To evaluate short-term and long-term fluctuations and learning effects in healthy subjects tested with the frequency doubling technique, which is based on a low spatial frequency and a high temporal frequency stimulus. METHODS: Twenty-three healthy adult subjects were consecutively recruited from volunteers, and 20 subjects finished the study. All the visual fields were assessed by the frequency doubling technique, program C-20, full threshold. The frequency doubling technique presents stimuli on a black-and-white video monitor with specialized control circuitry interfaced to a microprocessor. During program C-20, full threshold, 17 points are tested, one round point centrally and 16 square ones in the periphery up to 20 degrees of eccentricity. Each stimulus consists of a 0.25-cycle/degree sinusoidal grating undergoing a 25-Hz counterphase flicker. One eye of each patient was chosen at random. Each subject was tested once in the first session, three times in the second session, and once in the third and fourth sessions. Both short-term and long-term fluctuation were studied either as the average fluctuation value of all the points tested or as a point-to-point fluctuation. To study the learning effect, the results of the first session were compared with those of the second, the third, and the fourth sessions. RESULTS: The average mean sensitivity of the three examinations of the second session was 30.4 +/- 1.24 dB, and the average short-term fluctuation of all the subjects was 2.16 +/- 0.5 dB. The short-term fluctuation of each point tested ranged from 1.4 to 3.4 dB. The average mean sensitivity for all the sessions was 32.4 +/- 1.14 dB, with an average long-term fluctuation of 3.23 +/- 0.5 dB, and the long-term fluctuation of each tested point ranged from 2.5 to 4.4 dB. A mild learning effect was found between the first section and the others. CONCLUSION: Short-term and long-term fluctuations were similar to those known to occur with the conventional threshold perimetry when they were compared with the literature data. A learning effect was also observed and should be taken into account for the clinical use of this test.

Adult↗
PubMed2000

Frequency doubling technique in patients with ocular hypertension and glaucoma: correlation with octopus perimeter indices.

PURPOSE: To ascertain whether frequency doubling technique (FDT) (Welch-Allyn, Skaneateles, NY; Zeiss-Humphrey, San Leandro, CA) indices provide results comparable with those of standard Octopus threshold perimeters (Interzeag AG, CH-8952 Schlieren, CH) in patients with glaucoma and in patients suspected of having ocular hypertension, glaucoma, or both. DESIGN: A comparative, consecutive, case series. PARTICIPANTS: Thirty-nine glaucomatous patients and 41 patients with ocular hypertension or suspected glaucoma were recruited consecutively. METHODS: The visual field of the study participants were assessed by FDT program C-20 full threshold and Octopus program dG1X. Only one eye of each participant was selected randomly. Pearson's r correlation coefficient was calculated among the FDT and Octopus indices. MAIN OUTCOME MEASURES: Using Octopus perimeter, mean defect (MD), mean sensitivity (MS), loss variance (LV), and corrected loss variance (CLV) were calculated and used for correlation. For the FDT, mean deviation (FDT-MD) and pattern standard deviation (FDT-PSD) were calculated and used for correlation. Also, the time required to perform the visual field test was considered. RESULTS: In the entire population, a statistically significant correlation (Pearson's r, P<0.001) was found between FDT-MD and both MS (0.77) and MD (-0.80) and between FDT-PSD and both LV (0.50) and CLV (0.45). When the glaucoma group was considered alone, similar significant correlation was found between the indices. In the suspected ocular hypertension and glaucoma suspect group, no significant correlation was found. A significant (P<0.001) difference was found between FDT and Octopus for the time needed to perform the visual field test. CONCLUSIONS: This new technique could be used both to screen populations and to observe glaucomatous visual field progression in early and moderate stages. The FDT is a faster way to analyze the visual field and captures threshold values for each point, but it is important to remember that this is a new technique and its limits are still unknown.

Aged↗
PubMed2000

Comparison between relative dispersion analysis of high-pass resolution perimetry and standard threshold perimetry.

PURPOSE: To evaluate the correlation of the dispersion index (DI) of relative dispersion analysis (RDA), a new high-pass resolution perimetry (HRP) index, with other HRP indices and those of the Humphrey standard threshold perimeter (STP) parameters. METHODS: Sixty-eight eyes were randomly recruited. Thirty-one eyes were classified as glaucomatous (high intraocular pressure, abnormal visual field and/or optic disc) and 37 as ocular hypertensives (high intraocular pressure, normal visual field, normal optic disc). All the subjects were examined with Humphrey Perimeter, program 30-2, and HRP. The HRP data were also analysed with the RDA program. Statistical analysis was performed with Student's t-test, Pearson's r correlation coefficient, Mann-Whitney nonparametric test and Spearman correlation coefficient when appropriate. RESULTS: Within the entire sample significant correlations were found between the RDA index (DI) and all the HRP indices (p < 0.001) and corrected pattern standard deviation (p < 0.01), pattern standard deviation (PSD) (p < 0.01), mean deviation (p < 0.05) and short-term fluctuation (p < 0.05) of STP. A stronger correlation was found in glaucomatous patients. In subjects with ocular hypertension DI was only weakly correlated with PSD, local deviation and form index. No difference in DI was found between glaucoma and ocular hypertension. CONCLUSION: The DI of HRP has the theoretical capacity to detect localised inhomogeneity of retinal sensitivity, but at present our data do not support this hypothesis. Before any clinical applications of this index further studies are needed.

Adult↗