Understanding the complex dynamical interactions that occur during the evolution of a wildland fire still remains a challenge within the research community. Processes such as entrainment, the incident wind field, the interaction between neighboring updrafts, among other processes, motivates the need for more intensive measurement campaigns to determine the mechanisms responsible for the processes observed as wildland fire updrafts evolve. A recent opportunity to examine processes associated with wildland fires was made possible with a Doppler lidar (DL) mounted on a Twin Otter aircraft to measure horizontal and vertical winds during the 2019 Fire Influence on Regional‐to‐Global Environments and Air Quality campaign. Using the data collected, a technique was developed to isolate updrafts over designated hotspots with the intention of statistically analyzing the updraft samples as well as assessing specific cases that underscore the complex dynamical interactions generated by wildland fire behavior. Strong evidence in support of statistically derived relationships between the updraft characteristics and downdraft extrema at the flanks of updrafts are shown using methods developed herein. In addition to the influence of entrainment/detrainment on the updraft structure are features such as updraft displacement and interacting updrafts that could only be resolved by a high along‐ and cross‐beam resolution DL. Lastly, it was found that a high degree of symmetry between profiles to the left and right of core updrafts was preserved for most of the cases, which validates some of the assumptions typically used in idealized updraft formulations.
Objective: To describe characteristics of participants in the Complications of Age-Related Macular Degeneration Prevention Trial (CAPT) at baseline and to investigate associations among visual function, fundus features, and vision-related quality of life.Design: Cross-sectional study.Participants: The 1052 participants in CAPT, a multicenter, randomized clinical trial. Eligibility criteria for CAPT included 10 large drusen and visual acuity greater than or equal to20/40 in each eye.Methods: At baseline, the visual acuity, contrast sensitivity, and critical print size for each eye were measured, color stereo photographs of the disc and macula of each eye were taken, and the 25-item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25) was self-administered. Graders from a central photograph reading center evaluated the photographs for drusen characteristics and focal hyperpigmentation. All procedures were performed using standardized protocols. Associations among characteristics were assessed by Spearman correlation coefficients and multiple linear regression.Results: Among CAPT participants at baseline, the mean age was 71.0 years, 60.6% were women, and 99.3% were white. The median visual acuity of the better eye was 20/20 and of the worse eye 20/25. In approximately one third of eyes, drusen covered greater than or equal to10% of the retina within 3000 mum of the foveal center, and 67.7% of eyes had focal hyperpigmentation. Drusen area and focal hyperpigmentation were weakly correlated (r = -0.08 to -0.18) with the measures of visual function. The measures of visual function were weakly associated with the NEI-VFQ-25 scores. An association of fundus features with NEI-VFQ-25 scores was not found.Conclusion: At baseline, CAPT participants had good visual function and several risk factors for progression to neovascular age-related macular degeneration. Scores on the NEI-VFQ-25 indicated that participants perceived some problems with their vision. Within this relatively homogeneous group of participants, measures of visual function were only weakly associated with the measures of vision-related quality of life. (C) 2004 by the American Academy of Ophthalmology.
PURPOSE High-pass resolution perimeters such as the Ophthimus (High Tech Vision, Malmö, Sweden) may provide an easier, faster assessment of the visual field than conventional perimeters such as the Humphrey (Humphrey Instruments Inc., San Leandro, CA, U.S.A.), which is based on differential light sensitivity. The Ophthimus provides global indices and statistical analyses conceptually similar to those produced by the Humphrey. In addition, the Ophthimus provides, as a unique parameter, the estimated neural capacity. PATIENTS AND METHODS Twenty-one patients with chronic open-angle glaucoma and reliable fields on both Humphrey and Ophthimus testing were evaluated. The results from the two different techniques were compared. RESULTS The estimated neural capacity was correlated to global deviation and mean deviation at a statistically significant level. There were also correlations between mean deviation and global deviation and between pattern standard deviation and local deviation, but not between retest standard deviation and short-term fluctuation. CONCLUSION It is not clear at this point if the neural capacity of the Ophthimus provides any clinically useful information over and above global deviation. Mean test time was shorter with the Ophthimus system than the Humphrey. Performance on the reliability indices was better for the Ophthimus. The Ophthimus may prove useful in following patients with glaucoma.
We investigated retinal vascular changes in nine patients undergoing optic nerve sheath decompression for vision-threatening papilledema associated with pseudotumor cerebri. Two major (one superior and one inferior) retinal venous and arterial calibers were measured before and 1.1 +/- 0.1 months, 3.2 +/- 0.2 months, 5.0 +/- 0.2 months, 7.6 +/- 0.2 months, and 13.0 +/- 1.9 months after surgery. The retinal venous caliber decreased significantly, and the decrease progressed until 3.2 months after surgery. The venous caliber in the contralateral unoperated eyes also decreased significantly. The decrease in the venous caliber in the contralateral unoperated eye as well as in the operated eye following the surgery supports the hypothesis that slow filtration is the mechanism of successful optic nerve sheath decompression. Retinal venous caliber measurement, in either the operated eye or the unoperated fellow eye, can be used to quantitatively monitor the status of papilledema associated with pseudotumor cerebri.
The effect on intraocular pressure (IOP) of a 2-week washout following long-term ocular therapy with topical levobunolol or timolol for an average period of 30 months was investigated in 20 patients (11 whites and 9 blacks) with early primary open-angle glaucoma or ocular hypertensive glaucoma suspect status. The 2-week washout IOP was significantly lower than the pretreatment baseline IOP in the total 20 patients (P < 0.001), and in the 9 black patients (P = 0.004), but not in the 11 white patients (P = 0.065). However, the washout IOP was found to be significantly lower than the baseline IOP in the 5 whites with brown irides (P = 0.024) but not in the 6 whites with blue irides (P = 0.574). Thus, the 2-week washout following long-term ocular therapy with a topical beta 1-, beta 2-blocker appears insufficient to restore IOP to the pretreatment baseline level in blacks and in the whites with brown irides, whereas it may be adequate in the majority of the whites with blue irides.
In a prospective study, the addition of dipivefrin hydrochloride 0.1% twice daily to one eye of 32 patients with early primary open-angle glaucoma or ocular hypertension, maintained on a bilateral beta 1-, beta 2-blocker twice daily, resulted in a significant decrease of mean intraocular pressure (IOP) from 22.7 +/- 3.9 to 20.2 +/- 3.4 mmHg at 1 week (P = 0.0001) and to 21.0 +/- 3.8 mmHg at 12 weeks (P less than 0.02) in the dipivefrin-treated eyes. On the other hand, no significant change was noted in the fellow eyes (from 21.7 +/- 4.1 to 21.6 +/- 4.0 mmHg at 1 week and to 21.3 +/- 4.2 mmHg at 12 weeks). The addition of dipivefrin resulted in an IOP reduction of 2 mmHg or more in 50% and 3 mmHg or more in 19% of the eyes throughout the 12-week therapy. The result of the current study provides a realistic guideline as to what to expect from the common practice of adding dipivefrin hydrochloride to a beta 1-, beta 2-blocker regimen.
PURPOSE: To determine the accuracy of glaucoma detection by frequency-doubling perimetry. METHODS: Stereoview optic nerve photographs, visual field examination, intraocular pressure measurements, medical and ocular history, and a screening and full threshold frequency-doubling perimetry examination were performed in a prospective study of consecutive subjects. Inclusion criteria included age of 45 years or older, absence of ocular disease other than glaucoma, cataract, or mild drusen, and Snellen visual acuity of 20/60 or better. A total of 125 eyes in 102 glaucoma subjects and 95 eyes of 95 normal subjects were included. Each eye was classified as ''normal,'' ''glaucoma,'' or ''uncertain'' by each of three ophthalmologists on the basis of all available clinical information with the exception of frequency-doubling perimetry results. Those in the glaucoma group were subclassified as having early (n = 51), moderate (n = 42), or severe (n = 32) glaucoma on the basis of automated Humphrey visual field criteria. In the glaucoma group, two eyes from a subject were allowed to be included (23 of 102 subjects) if they differed in level of damage because they were never analyzed within the same statistical analysis. RESULTS: Several diagnostic algorithms were evaluated. Algorithms based on the most depressed single point, pair of adjacent points, and cluster of three points performed nearly identically. For the screening test, if any abnormality was identified, specificity was 95%, whereas sensitivity was 39%, 86%, and 100% for early, moderate, and severe glaucoma, respectively. For the full threshold test, with at least one point depressed to the P < 0.5% level, specificity measured 91%, whereas sensitivity was 35%, 88%, and 100% for early, moderate, and severe glaucoma, respectively. The two global indices, mean deviation and pattern standard deviation, were also evaluated and were generally less accurate. CONCLUSION: Frequency-doubling perimetry, which is rapid and easily administered, is effective at detecting moderate and severe disease and appears well suited for glaucoma screening. Visual function-specific perimetry for indirect comparison of different ganglion cell populations in glaucoma. PURPOSE: To compare short-wavelength automated perimetry, frequency-doubling technology perimetry, and motion-automated perimetry, each of which assesses different aspects of visual function, in eyes with glaucomatous optic neuropathy and ocular hypertension. METHODS: One hundred thirty-six eyes from 136 subjects were evaluated with all three tests as well as with standard automated perimetry. Fields were not used in the classification of study groups to prevent bias, because the major purpose of the study was to …