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Biomedical subjects

J Caprioli

Publications and source records attributed to J Caprioli.

At least 91 records · Page 5Linked to original sources
PubMed1989

Measurements of peripapillary nerve fiber layer contour in glaucoma.

We developed a method to quantify the surface contour of the peripapillary nerve fiber layer from simultaneous stereoscopic videographic images. Parameters that describe this contour are defined and compared to standard optic nerve structural parameters (cup/disk ratio, disk rim area, cup volume) in three age-matched groups of patients: 52 normal controls, 79 glaucoma suspects, and 101 glaucoma patients. Greater discriminatory information was obtained from the measurements from the superior and inferior quadrants than from the measurements from the temporal and nasal quadrants. This approach helps identify new structural markers that may more closely reflect the number of ganglion cell axons in the optic nerve. Such measurements made longitudinally in living eyes will provide valuable information about the relative rates of ganglion cell death in aging and in glaucoma.

Adult↗
PubMed1989

Measurement of relative nerve fiber layer surface height in glaucoma.

A new parameter of structural optic nerve damage from glaucoma is reported, the relative nerve fiber layer surface height (RNFLH). Relative nerve fiber layer surface height is calculated from magnification-corrected surface contour measurements of the peripapillary retina made with computerized image analysis of stereoscopic videographic images. The technique measures the average height of the nerve fiber layer surface within a circumference 200 microns from the disc edge, as detected with narrow-band green light, with respect to a standardized reference plane. This parameter was examined in a group of 36 glaucoma patients with early to moderate visual field loss, and in 33 age-matched normal controls. The measured surface of the peripapillary nerve fiber layer was, on the average, 74 microns lower in glaucomatous eyes than in normal eyes, a statistically significant difference (P = 0.000). The ability of RNFLH to distinguish glaucomatous eyes from normal eyes was tested by its sensitivity (83%) and specificity (88%), which were greater than the sensitivities and specificities of computerized measurements of cup-disc ratio, disc rim area, and cup volume. This approach represents a step toward the identification of quantitative structural parameters to reflect the number of retinal ganglion cell axons that enter the optic nerve. Such measurements may facilitate the early diagnosis of glaucoma and provide important information on rates of ganglion cell death in aging and disease.

Female↗
PubMed1989

Adenylate cyclase stimulation and intraocular pressure reduction by forskolin analogs.

Forskolin and 18 chemical analogs of forskolin were assayed for stimulation of adenylate cyclase activity in vitro and for their effects on intraocular pressure (IOP) in vivo. Adenylate cyclase activity was determined with a preparation of corpora striata from male Wistar rats and test drug concentrations of 0.3 to 300 microM. IOP effect was monitored after a single topical ocular application of a 1% suspension of the test drug to male New Zealand albino rabbits. Significant reductions in IOP occurred with compounds which had potent cyclase stimulatory properties. Most compounds with little cyclase stimulatory effect produced little or no decrease in IOP. A 1-substituted morpholino-acetoxy derivative, which may be a prodrug metabolized to active form by corneal esterases, showed little cyclase stimulation in vitro but produced significant reductions in IOP.

Adenylyl Cyclases↗
PubMed1989

Correlation of visual function with optic nerve and nerve fiber layer structure in glaucoma.

Careful clinical correlation of the appearance of the optic nerve and retinal nerve fiber layer with measurements of the visual field is an important aspect of the evaluation of patients with glaucoma. The anatomy of the nerve fiber layer and its retinotopic projections to the optic nerve head form the basis of the spatial relationships between structure and function in glaucoma. Clinical experience with the temporal correlations of structure and function indicates that visible alterations of the optic nerve and surrounding nerve fiber layer may occur before scotomas in the visual field can be detected. Quantitative clinical studies of the optic nerve and visual field support this concept, and provide additional clues regarding the pathogenesis of glaucomatous optic nerve damage.

Glaucoma↗
PubMed1988

Measurement of optic nerve blood flow with iodoantipyrine: limitations caused by diffusion from the choroid.

Radioactively labelled iodoantipyrine has been used to measure optic nerve blood flow in experimental animals. The reliability of blood flow measurements with this technique may be limited by diffusion of tracer from the nearby choroid. The activity of tracer in the peripapillary choroid and anterior optic nerve was measured in a series of in vivo optic nerve blood flow experiments in cats. The diffusion of iodoantipyrine into cat optic nerve segments was also measured in vitro, and a model for diffusion of tracer from the peripapillary choroid into the anterior optic nerve was developed. The activity profiles established by simple diffusion experiments were similar to the activity profiles in the anterior optic nerve established by blood flow experiments. Apparent blood flow measurements in the anterior optic nerve made with iodoantipyrine may be largely influenced by tracer diffusion from the nearby choroid. For measurements of tracer activity which are statistically similar between control and experimental optic nerve samples, and with a total diffusion time of 60 sec (a well-done experiment), real blood flow in the experimental sample may differ by as much as 60% from the control at a point 50 micron from the choroid. At 300 micron from the choroid, the maximum undetectable difference because of diffusion declines to approx. 12%. These estimates assume an autoradiographic technique which can reliably detect tissue tracer activity differences of +/- 10%. Measurements of optic nerve blood flow made with diffusible tracers are affected by diffusion from the choroid and should be reported with estimated limits of reliability.

Animals↗
PubMed1988

Correlation of structure and function in glaucoma. Quantitative measurements of disc and field.

The relationship between quantitative structural measurements of the optic nerve head and quantitative measurements of the visual field in glaucoma was studied. Computerized videographic image analysis (Rodenstock Analyzer) was used to obtain cup-disc ratio, disc rim area, and cup volume in 50 glaucoma suspects and 37 glaucoma patients. The visual field indices, mean defect and loss standard deviation, were calculated from Octopus Program 32. There were statistically significant linear correlations between each of the optic nerve structural parameters and visual field mean defect and loss standard deviation. The strongest correlation was between disc rim area and visual field mean defect (r = -0.49), which are both global measures of glaucomatous damage. The correlations were not strong enough to readily allow the recognition of early nerve damage by the parameters analyzed thus far. Closer correlations may be evident if structural parameters can be found that more accurately reflect the number of surviving axons in the optic nerve head.

Female↗
PubMed1988

Videographic quantification of optic disc pallor.

Digitized images of the optic disc, acquired videographically (Rodenstock Analyzer) under green (540 nm) and red (640 nm) illumination, were used to quantify optic disc pallor. The pallor density of each pixel was defined as twice the reflectance under green illumination divided by the sum of the reflectance under red and green illumination. Pallor densities can range from 0 (red) to 1 (white); typical median values were 0.25 for vessels, 0.40 for healthy disc rim, and 0.70 for the lamina cribrosa. The variability of pallor measurements using this technique was determined. Two uniform color fields (Farnsworth-Munsell 100-Hue Test color chips 1 and 18) were imaged five times each using a model eye. Significant (P less than 0.0001) drift of mean pallor densities occurred between images of both sets. The optic discs of seven normal eyes and of seven glaucomatous eyes were imaged nine times each. The non-normal frequency distribution of pallor densities for each image was described by trimmed means and a measure of distribution width. Variability was defined as the standard deviation of the measurements divided by the full scale pallor density. The variability of the trimmed means increased with pallor density (r = 0.99, P less than 0.0001). The variability of distribution width was smaller than that of the mean values, and averaged 3.4% in normal and glaucomatous eyes. Videographic reflectometry may provide useful, quantitative measurements of optic disc pallor.

Glaucoma↗
PubMed1988

Videographic measurements of optic nerve topography in glaucoma.

Topographic measurements of the optic nerve head were made with computerized videographic image analysis (Rodenstock Analyzer) in one eye each of 36 normal controls, 41 glaucoma suspects and 46 glaucoma patients matched for age. Glaucoma suspects had elevated intraocular pressures and normal visual fields in both eyes. Glaucoma patients had typical visual field defects. Disc measurements were corrected for the optical dimensions of individual eyes. One-way analysis of variance revealed statistically significant differences among the diagnostic groups for cup-disc ratio (P = 0.0006), disc rim area (P less than 0.0001) and cup volume (P = 0.0001). Mean (+/- SEM) disc rim area was 1.14 +/- 0.04 mm2 for controls, 1.10 +/- 0.04 mm2 for glaucoma suspects and 0.87 +/- 0.05 mm2 for glaucoma patients. Mean (+/- SEM) optic nerve cup volume was 0.35 +/- 0.02 mm3 for controls, 0.44 +/- 0.04 mm3 for glaucoma suspects and 0.60 +/- 0.05 mm3 for glaucoma patients. Planimetric measurements of disc rim area were made from manual tracings of stereoscopic disc photographs of the same eyes. There was a statistically significant correlation between the computerized videographic measurements and the manual photographic measurements of disc rim area (r = 0.73, P less than 0.0001). The broad range of values for these optic nerve structural parameters in normal eyes and their overlap with values in glaucomatous eyes prevents their use to reliably predict which patients are normal and which have glaucomatous visual field loss. New parameters are required to fully describe the depth information generated with new quantitative techniques.

Adult↗
PubMed1987

Patterns of early visual field loss in open-angle glaucoma.

We examined two groups of patients with primary open-angle glaucoma with distinctly different patterns of early visual field loss using two visual field indices: mean defect and loss variance. Patients were selected on the basis of visual field criteria only. Eight patients were selected for diffuse depression of the differential light sensitivity without localized scotomas (mean defect greater than 3.0 decibels, loss variance less than 10.0 decibels). Seven patients were selected for localized scotomas without diffuse depression of the differential light sensitivity (mean defect less than or equal to 3.0 decibels, loss variance greater than or equal to 20.0 decibels). Patients with diffuse depression manifested intraocular pressures that were higher (mean peak pressure +/- S.E.M., 27.6 +/- 1.2 mm Hg) than those with localized defects (22.4 +/- 1.4 mm Hg). The optic disk rim area of the localized loss group (mean +/- S.E.M., 1.02 +/- 0.15 mm2) was significantly smaller (P less than .05) than the disk rim area of the diffuse loss group (1.33 +/- 0.07 mm2). This difference was largely because of thinner temporal disk rims in the localized loss group. Different patterns of visual field loss may be caused by different mechanisms of glaucomatous optic nerve damage.

Aged↗
PubMed1987

Optic disc rim area is related to disc size in normal subjects.

Measurements of optic disc rim area are used to quantitatively evaluate the optic nerve head in open angle glaucoma. It has been suggested that disc rim area (neuroretinal rim area) is independent of disc size, unlike measurements of cup-disc ratio that co-vary with measurements of disc size. To test the relationships between topographic optic disc measurements and disc size, we used computerized image analysis (Rodenstock analyzer) of the optic nerve head to measure total disc area, cup area, disc rim area, and disc cup volume in 38 normal subjects. Magnification-corrected measurements of cup area, disc rim area, and cup volume were positively correlated with measurements of disc area. Measurements of disc rim area were therefore not independent of disc size in this group of normal subjects. A normal range of values for disc rim area can be predicted for an eye depending on the area of its optic disc. Sensitive predictions require further refinement based on the patient's age, race, and sex.

Aged↗
PubMed1987

Quantitative evaluation of the optic nerve head in patients with unilateral visual field loss from primary open-angle glaucoma.

Measurable structural alterations of the optic nerve head may precede visual field abnormalities in early open-angle glaucoma. The authors studied the optic nerve heads of 10 patients with unilateral visual field loss from primary open-angle glaucoma, and 12 age- and sex-matched normal subjects. Topographic optic nerve head parameters were measured with a system of computerized image analysis (Rodenstock Analyzer, G. Rodenstock Instrumente GMBH, Munich, W. Germany). In patients with asymmetric primary open-angle glaucoma, eyes with normal visual fields had a slightly larger mean (+/- standard error of the mean) disc rim area (0.90 +/- 0.04 mm2) than eyes with glaucomatous visual field defects (0.78 +/- 0.05 mm2). However, both sets of eyes in the asymmetric primary open-angle glaucoma patients had smaller mean disc rim areas (P less than 0.0007) than did the control group (1.27 +/- 0.09 mm2). These findings support the hypothesis that loss of the optic disc rim can be detected before perimetric abnormalities develop in primary open-angle glaucoma.

Female↗
PubMed1987

Celiprolol versus timolol and placebo: a two week double-blind comparison.

Celiprolol (5%) was compared to timolol (0.5%) and placebo in patients with primary open angle glaucoma or ocular hypertension. A total of 28 patients participated in this double blind study and received treatment for two weeks. Intraocular pressure decreased an average of 4.4 mmHg with celiprolol and 7.1 mmHg with timolol two hours after instillation. This was maintained 12 hours after administration of timolol but not after celiprolol. There was a small but statistically significant decrease in pulse rate 2 hours after administration of timolol (from 72 to 64 beats per minute) which was not observed after celiprolol. Side effects were mild and similar for all 3 groups.

Adrenergic beta-Antagonists↗
PubMed1987

Chorionic gonadotropin decreases intraocular pressure and aqueous humor flow in rabbit eyes.

The effect of human chorionic gonadotropin (hCG) on the rabbit eye was studied. Intravitreal injections of hCG in albino rabbits provoked a reduction of intraocular pressure (IOP). Intravenous administration of hCG in single doses of 5,000-10,000 units in male pigmented rabbits caused a significant reduction in IOP from 1.5-5 hr after injection. When two successive intravenous doses of 5,000 units of hCG were given at 0 and 3 hr to pigmented rabbits, a significant reduction of net aqueous flow occurred, as measured by scanning fluorophotometry. These results indicate that the decrease in aqueous flow rate in the rabbit eye after administration of hCG can account for the reduction in IOP.

Animals↗
PubMed1986

Regulation of intraocular pressure during cyclocryotherapy for advanced glaucoma.

Five eyes of five patients with advanced glaucoma were treated with cyclocryotherapy. Intraocular pressure was monitored by applanation tonometry during the procedure and for the first 24 hours postoperatively. Two patients underwent a standard form of treatment, and exhibited two components of acute increases in intraocular pressure as a result of the procedure. Intraoperatively, intraocular pressure increased abruptly to 60 to 80 mm Hg during the freezing phase of cyclocryotherapy and decreased to baseline levels during the thaw phase. Postoperatively, intraocular pressure increased to approximately 50 mm Hg, peaking six hours after the procedure. We devised a method of manometric regulation of intraocular pressure to prevent significant increases during cyclocryotherapy and used it in three patients. This group maintained intraocular pressures of approximately 25 mm Hg intraoperatively, and exhibited blunted postoperative increases. Manometric regulation of intraocular pressure during cyclocryotherapy for advanced glaucoma may protect seriously compromised optic nerves from further damage, and may represent a safer method of treatment.

Adolescent↗
PubMed1986

Reproducibility of optic disc measurements with computerized analysis of stereoscopic video images.

Computerized digital image analysis of the optic nerve head was performed using a simultaneous stereoscopic video camera system to provide rapid, quantitative measurements of optic nerve head topography. Determination of the variability of the measurements is required to estimate the magnitude of optic nerve change over time that can be reliably detected. Total variability, operator variability, and interoperator variability were studied. Total variability was assessed by analyzing ten sets of video recordings made in each of seven eyes of seven normal subjects, and in seven eyes of seven patients with glaucoma. The median coefficients of variation for measurements of total variability in glaucoma patients were as follows: vertical disc measurement, 1.4%; horizontal disc measurement, 2.1%; disc area, 1.9%; vertical cup/disc, 3.9%; horizontal cup/disc, 3.3%; disc rim area, 7.5%; and volume, 7.6%. Operator and interoperator variabilities were considerably smaller in magnitude.

Data Display↗
PubMed1986

Anterior chamber depth in open angle glaucoma.

Anterior chamber depth was measured in patients with primary open angle glaucoma, low tension glaucoma, pigmentary dispersion syndrome, and glaucoma suspects. Multiple linear regression analysis demonstrated that anterior chamber depth is a function of sex, age, and refractive error. Values for anterior chamber depth corrected for age and refractive error were greater in patients with pigmentary dispersion syndrome than in patients with other forms of open angle glaucoma or in glaucoma suspects.

Age Factors↗