Cholera toxin increases Na+/K+-ATPase activity in the RN22 Schwann cell line.
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Animals↗
Biomedical subjects
W C Stewart
Publications and source records attributed to W C Stewart.
Pattern discrimination perimetry in patients with glaucoma and ocular hypertension.
We compared the results of the pattern discrimination perimeter to the program 30-2 on the Humphrey Field Analyzer (Humphrey, Inc., San Leandro, California) in 93 consecutive patients with ocular hypertension and glaucoma and 30 control patients. In 20 patients with ocular hypertension, a significantly greater number of glaucomatous defects were noted on pattern discrimination perimetry (ten patients) than on the program 30-2 (two patients) (P less than .05, Wilcoxon signed rank test). The diversity in diagnoses found on pattern discrimination testing was not explained by age, intraocular pressure, refraction, number of glaucoma medicines, race, presence of vascular disease, optic disk status, or pupil size. In contrast, in 73 patients with glaucoma no statistical difference in the severity of diagnoses was noted between perimeters (P greater than .05, Wilcoxon signed rank test). These results suggest the potential value of pattern discrimination perimetry as a visual function test in patients with glaucoma and in defining subsets of patients with ocular hypertension not found with conventional automated perimetry.
Adult↗
Long-term and short-term fluctuation in pattern discrimination perimetry.
We studied threshold fluctuation with the pattern discrimination perimeter in 24 healthy subjects at 56 locations within the central 30 degrees. This perimeter evaluates a subject's ability to discriminate a patterned stimulus measured by a percentage scale. We found an intraindividual fluctuation of 10.52% and an interindividual fluctuation of 8.78%. A statistically increased intraindividual, but not interindividual fluctuation was noted with increasing eccentricity from fixation (P less than .05, Bartlett's test). However, no correlation in fluctuation was noted with advancing age or increasing false-positive errors (P greater than .05, correlation coefficient). Also, no difference in fluctuation between superior or inferior hemifields was observed (P greater than .05, Student's t-test). The average threshold across all subjects was 54.3%, which provided an upper limit of normal, two standard deviations from the mean, of less than 80% for most locations. This study indicates that fluctuation should be considered when interpreting pattern discrimination fields, but that the extent of fluctuation generally allows for an adequate separation between normal and abnormal measurements.
Adult↗
Semiconductor diode laser transscleral cyclophotocoagulation in patients with glaucoma.
We used the semiconductor diode laser to perform transscleral cyclophotocoagulation in 14 patients with glaucoma. Laser settings used for this procedure were 990 milliseconds, 100-microns spot size, and 1,200 mW of power. Applications were placed 1 mm posterior to the surgical corneoscleral limbus and 1 mm defocused toward the ciliary body. The mean preoperative intraocular pressure was 34.8 +/- 13 mm Hg, and the mean intraocular pressure six months after a single treatment session was 24.3 +/- 18 mm Hg (P greater than .001, paired t-test). The mean number of glaucoma medications decreased from 2.2 preoperatively to 1.4 postoperatively. Complications included conjunctival burns and uveitis in 14 patients, and pain in one patient. These results suggested that semiconductor diode transscleral cyclophotocoagulation may be useful as a treatment to reduce the intraocular pressure in patients with glaucoma.
Adult↗
Temporal visual field in glaucoma: a re-evaluation in the automated perimetry era.
We prospectively studied 152 glaucoma patients (192 eyes) and 31 normal subjects (31 eyes) tested with the 30-2 program and a customized temporal periphery program on the Humphrey Field Analyzer to determine the usefulness of routine testing temporal to the blind spot. We found that in 53 glaucomatous and each of 31 control eyes the central 30 degrees and temporal peripheral field were normal. In eyes with glaucomatous defects, testing temporal to the blind spot provided information equivalent to the central Bjerrum area in 66 eyes, less in 62 eyes, and more in 11 eyes. Temporal field testing was most useful in eyes with a diffusely depressed Bjerrum area (mean defect less than -8.30 dB). This study suggests that automated static perimetry commonly reveals glaucomatous defects temporal to the blind spot, but usually adds significant information over central testing only in patients with late visual field changes.
Adult↗
Use of the argon laser to close filtering bleb leaks.
We attempted to seal 15 consecutive filtering bleb leaks in 11 patients using argon laser energy. Eight leaks were at the conjunctival-corneal interface associated with a fornix-based flap, 4 leaks resulted from suture scissoring of the conjunctiva, and 3 leaks were button-holes in the conjunctiva. Thirteen leaks occurred within 2 weeks after filtering surgery, while 2 were of late onset. Argon laser parameters used were a 500-microns spot size, 0.1-s time interval, and between 500 and 1800 mW of power. Thirteen leaks were sealed after one or two laser sessions, while 2 leaks required other treatment modalities. Complications included conjunctival fenestration and transient corneal stromal opacities. This study suggests that the argon laser can be used to seal filtering bleb leaks in many patients following filtering surgery.
Adult↗
The effect of stimulus duration upon the components of fluctuation in static automated perimetry.
We studied the effect of varying the stimulus duration time on the components of fluctuation in static automated perimetry by testing 20 healthy subjects on the Humphrey Field Analyser within the central 20 degrees of vision. We found the total fluctuation at a stimulus duration of 0.065 s, to be 3.22 decibels (dB); 0.1 s, 3.22 dB; 0.2 s, 3.34 dB; 0.3 s, 2.95 dB; 0.4 s, 3.24 dB; and 0.5 s, 3.22 dB. Little difference was observed in the individual components (short-term, long-term homogeneous, long-term heterogeneous and inter-individual) or total fluctuation with an increasing stimulus presentation time when evaluated over the entire visual field or in a pointwise fashion. This study suggests that the stimulus duration within the range of times studied has little effect on the components or total fluctuation in healthy individuals.
Adolescent↗
Questionnaire versus clinical interview in the diagnosis of headache.
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Evaluation Studies as Topic↗
Static versus kinetic testing in the nasal peripheral field in patients with glaucoma.
One-hundred and seventy-seven subjects (207 eyes) were tested on the Humphrey Field Analyzer to evaluate the usefulness of static and kinetic peripheral nasal visual field testing in identifying glaucomatous defects. In 20 of the 187 glaucomatous or ocular hypertensive eyes glaucomatous defects were found in the peripheral nasal field while the central 30 degrees remained normal or showed non-specific diffuse depression. Kinetic peripheral nasal field testing identified 17 of these eyes while the static testing identified eleven. This difference was not statistically significant (P greater than 0.05, Stuart-Maxwell test). Twenty control eyes showed one glaucomatous peripheral nasal defect on static testing, and none with kinetic testing. These results differed statistically from the diagnoses in the diseased population (P less than 0.005, chi 2-test). This study suggests the potential value of nasal peripheral field testing in selected glaucoma patients for which static testing has no apparent diagnostic advantage over kinetic techniques.
Adolescent↗
Association of reliability with reproducibility of the glaucomatous visual field.
We studied 207 glaucoma patients (207 eyes) who had two successive visual tests on the Humphrey Field Analyzer to determine the association of unreliability (> 10% incidence of a missed catch trial test) with threshold variation. We found that in patients where one visual field showed > 30% false negative or positive errors, and the other visual field also was unreliable, a significant increase in the variance of the mean defect existed from reliable patients (p < 0.05). Of patients who had only one of two visual fields which was unreliable (from false negative errors), only those with marked glaucomatous visual field loss (< -15 dB depth of defect) showed a greater variance in mean defect between examinations over reliable patients (p < 0.05). In total, 41 patients (19.8%) had unreliable visual fields associated with statistically increased threshold variation. This study suggests that patient reliability should be considered when interpreting changes in threshold between automated visual field examinations.
Aged↗
The effect of varying wavelength on subconjunctival scleral laser suture lysis in rabbits.
We studied laser suture lysis of subconjunctival scleral sutures in a rabbit eye using selected wavelengths from a dye and diode laser to determine which wavelength caused the least conjunctival damage. We found an oval shaped area of coagulation necrosis surrounding the suture track in the conjunctival substantia propria measuring in depth 61.0 mu for 488 + 514 nm (blue-green), 105.7 mu for 514 nm (green), 148.3 mu for 630 nm (red), and 29.0 mu with 780 + 830 nm (infrared) wavelengths. No observable damage was noted with 585 nm (yellow) or 610 nm (orange) wavelengths. The energy intensity required for suture lysis was similar across each wavelength studied. No damage was observed in the sclera or conjunctival epithelium. These findings suggest that using the yellow or orange wavelength, when performing laser suture lysis clinically, potentially may limit conjunctival damage.
Animals↗
Infectious disease risks of fibrin glue.
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Eye Infections↗
Histologic differences in the conjunctiva of black and white glaucoma patients.
We compared perioperative conjunctival biopsy specimens from 31 consecutive trabeculectomy patients to determine if there were any histologic differences between black and white glaucoma patients. We found a statistically significantly greater mean and distribution of mast cells and neutrophils in the white patients. No significant difference was found in the mean number of goblet cells, eosinophiles, macrophages, fibroblasts, plasma cells, or lymphocytes; or in thickness of the epithelium, vascular density, or collagen or mucopolysaccharide staining. We conclude that histological conjunctival factors that could be evaluated preoperatively probably are not related to the poor results in black patients of filtration surgery noted by some investigators.
Aged↗
Correlation between intraocular pressure control and progressive glaucomatous damage in primary open-angle glaucoma.
Fifty-five patients with primary open-angle glaucoma and early glaucomatous damage who had medical therapy and laser trabeculoplasty were followed up for four to 11 years or until progressive glaucomatous damage was documented. Factors associated with the stability or progression of glaucoma were evaluated. Eyes with mean intraocular pressure higher than 21 mm Hg during the follow-up period uniformly had progressive glaucomatous changes. Conversely, eyes with mean intraocular pressure less than 17 mm Hg remained stable, and approximately half of the eyes with mean intraocular pressure between 17 and 21 mm Hg had progressive glaucomatous changes. Patients who remained stable were slightly younger than those with progressive glaucomatous changes (P less than .05), but initial optic nerve head appearance, initial visual field findings, number of medicines used, medical history, and patient gender or race were not statistically associated with stability or progression of the glaucoma. These findings reinforce the importance of intraocular pressure control in primary open-angle glaucoma and the need to identify other markers that help determine the proper level of intraocular pressure for individual patients.
Adult↗
Carcinoma arising in an odontogenic keratocyst with orbital invasion.
A 54-year-old black female presented with proptosis and reduced visual acuity of the left eye. Computerized tomography (CT) revealed tumor involvement of the left cavernous sinus and posterior orbit. The patient had a nineteen year history of a left-sided jaw tumor which recurred despite surgical and radiation therapy. Biopsy demonstrated a parakeratinized odontogenic keratocyst with areas of transformation into an invasive squamous cell carcinoma. Although a parakeratinized odontogenic keratocyst may be locally invasive, to our knowledge, no case of a parakeratinized odontogenic keratocyst involving the orbit or cavernous sinus previously has been reported.
Carcinoma, Squamous Cell↗
Influence of missed catch trials on the visual field in normal subjects.
A total of 20 healthy individuals purposely missed an increasing number of individual catch trial questions (false positive or negative errors or fixation losses) when tested on the Humphrey Field Analyzer to determine the effect on the normal visual field. As determined by Statpac, the global indices and probability maps became significantly altered from those for the control fields at a prevalence of 20% for false negatives and 33% for fixation losses and false positives. However, the perimeter's recorded prevalence of missed catch trials showed a wide distribution from the percentage purposely missed. A high prevalence of missed catch trials was also indicated by a greater than normal mean defect and number of questions asked. This study suggests that although the number of missed catch trials are often recorded inaccurately, they help to identify unreliable normal visual fields, as do the mean defect and the number of questions asked.
Adult↗
A 3-month comparison of 1% and 2% carteolol and 0.5% timolol in open-angle glaucoma.
Carteolol, a nonselective beta-adrenergic antagonist with intrinsic sympathomimetic activity, was compared in 1% and 2% topical solutions with 0.5% timolol in 105 patients with primary open-angle glaucoma. In this double-masked, randomized 3-month trial, all three preparations significantly lowered intraocular pressure throughout the study, with no significant differences being observed. There were also no significant differences among the three preparations with regard to ocular or systemic adverse reactions, including heart rate and blood pressure.
Administration, Topical↗
The effect of background intensity on the components of fluctuation as determined by threshold-related automated perimetry.
We studied the effect of various background intensities on the components of fluctuation by testing 20 healthy subjects on the Humphrey Field Analyzer. Our results show little difference in the total fluctuation between two low photopic background intensities similar to those commonly used on commercial perimeters: 3.02 dB for 31.5 apostilbs (asb) and 2.77 dB for 3.15 asb. However, an increase in total fluctuation (3.74 dB for 0.315 asb and 4.24 dB for 0.0315 asb) as well as in its short-term, long-term heterogeneous, and interindividual components was seen at mesopic background intensities as compared with the low photopic range. This study suggests that in healthy individuals, little difference exists in the fluctuation resulting from differences in background intensities commonly used on commercial perimeters, whereas mesopic illumination may increase the variability of threshold responses.
Adult↗