Photometry in goldfish by electrophysiological recording: comparision of criterion response method with heterochromatic flicker photometry.
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Adaptation, Ocular↗
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Laser flare photometry and complications of chronic uveitis in children.
PURPOSE: To investigate possible relationships between laser flare photometry values, complications of uveitis, and outcomes in children with chronic uveitis. DESIGN: Retrospective chart review. METHOD: We evaluated patients with active, noninfectious anterior, intermediate, or panuveitis who were 16 years of age or younger and who had laser flare photometry at one of two academic institutions. Complications enumerated at baseline and during follow-up were compared with laser flare photometry values and to anterior chamber cell counts. RESULTS: At least one laser flare photometry value ("flare"), defined as baseline measurement, was available for 59 patients (41 girls, 18 boys; mean age, 10.3 +/- 3.5 years); 38 of these patients had at least one additional measurement during follow-up (median 11 months). Complications of uveitis were present in 35 patients (59%) at baseline. There was a positive association between increased laser flare photometry values and complications at baseline (any complication [P =.007], posterior synechiae [P =.003]). The development of complications during follow-up was associated with the presence of complications at baseline (P =.018). A subgroup of patients with low flare at baseline had no complications during follow-up regardless of treatment given. CONCLUSIONS: There is a positive relationship between laser flare photometry values and the prevalence of complications of uveitis in children. Laser flare photometry provides a novel way to monitor children with uveitis. Future study will be needed to determine whether values have prognostic importance and whether a treatment strategy that minimizes flare results in fewer uveitic complications.
Aqueous Humor↗
Elevation of laser flare photometry in patients with cytomegalovirus retinitis and AIDS.
PURPOSE: To investigate an alteration of the blood-ocular barriers by laser flare photometry in patients with acquired immunodeficiency syndrome (AIDS) diagnosed with cytomegalovirus retinitis. METHODS: Serial laser flare photometry measurements from 31 eyes of 31 patients with AIDS and newly diagnosed cytomegalovirus retinitis were compared with measurements from 31 control patients with AIDS but without documented eye disease. Location and extent of retinitis, presence of visual symptoms, and CD4 lymphocyte counts were also compared with laser flare photometry readings. RESULTS: Laser flare readings (mean +/- SE) were significantly higher in eyes with (13.0 +/- 1.5 photon counts per msec) than without cytomegalovirus retinitis (4.9 +/- 0.3 photon counts per msec) (P < .001). Lesions within the arcade vessels resulted in significantly higher laser flare photometry readings (17.3 +/- 2.5 photon counts per msec) compared with peripheral retinitis (9.8 +/- 1.5 photon counts per msec) (P = .01). A significant correlation was found between area of involvement of peripheral retinitis and laser flare photometry readings (P = .008). Readings in patients without cytomegalovirus retinitis increased significantly 10 months after the first measurement (9.5 +/- 1.9 photon counts per msec) (P = .04). Readings in patients with cytomegalovirus remained elevated 3 months after successful treatment of retinitis (12.3 +/- 2.3 photon counts per msec) (P = .6). CONCLUSIONS: Laser flare photometry readings are significantly elevated in eyes with cytomegalovirus retinitis, suggesting a breakdown of the blood-ocular barriers. Increasing laser flare photometry readings over time in patients without known ocular disease suggests that HIV infection may cause progressive breakdown of the blood-ocular barrier.
Acquired Immunodeficiency Syndrome↗
Relationships between laser flare photometry values and complications of uveitis.
OBJECTIVE: To determine whether relationships exist between elevated laser flare photometry values and common abnormalities and complications associated with uveitis. METHODS: We retrospectively studied all patients with uveitis on whom laser flare photometry measurements ("flare") were obtained (N = 111) at 2 academic medical centers. The first laser flare photometry values obtained for each patient were compared with the presence or absence of the following abnormalities or complications associated with uveitis: keratic precipitates, posterior synechiae, cataract, macular edema, optic disc edema, and glaucoma. In bilateral cases, the eye with the higher flare was used in primary analyses. RESULTS: Flare was significantly higher in patients with posterior synechiae (P<.001) and in those with macular edema (P =.02) than in patients with uveitis who did not have these complications. Flare was significantly higher in patients with prior cataract surgery or cataract at the study visit than in those without cataracts (P =.001). There was no significant difference in flare between patients with and without keratic precipitates, optic disc edema, or glaucoma. No relationships were found between abnormalities or complications and the level of inflammatory cells or flare as determined by clinical assessment. We also identified an inverse relationship between flare and visual acuity that was not completely explained by the presence of complications in a stepwise regression model. CONCLUSIONS: Although causal relationships were not established, associations between flare and some complications of uveitis suggest that aqueous humor protein may be an important factor in the development of these problems. Consequently, laser flare photometry could play a role in predicting outcomes or monitoring therapy for patients with uveitis.
Adolescent↗
Evaluation of laser flare-cell photometry in the appraisal and management of intraocular inflammation in uveitis.
BACKGROUND: Laser flare-cell photometry enables objective and quantitative measurement of anterior chamber inflammation. Systematic data currently are used mainly for clinical research; few are yet available in uveitis. The authors prospectively studied the amount, duration, and pattern of inflammation for well-defined uveitic conditions and evaluated the potential usefulness of laser flare-cell photometry in uveitis. METHODS: Mean initial flare was calculated in HLA-B27-positive acute anterior uveitis, acute herpes zoster uveitis, acute retinal necrosis (ARN), Fuchs heterochromic cyclitis, intermediate uveitis (pars planitis-type), posterior sarcoidosis, posterior pole toxoplasmosis, and birdshot chorioretinopathy. Evolution of aqueous flare and cells was analyzed for acute anterior uveitis, ARN, and pars planitis treated for cystoid macular edema (CME), all of which received a standardized therapy. RESULTS: Blood-aqueous barrier disruption was very pronounced in acute anterior uveitis (170.2 +/- 33 photons/msecond), ARN (177.4 +/- 88 photons/msecond), moderate in posterior sarcoidosis (38.1 +/- 11 photons/msecond), acute zoster uveitis (25.8 +/- 6.1 photons/msecond), and pars planitis (19.1 +/- 2.9 photons/msecond) but only minimal in Fuchs heterochromic cyclitis (10.2 +/- 3.5 photons/msecond), toxoplasmosis (9.0 +/- 1.2 photons/msecond) and birdshot chorioretinopathy (5.7 +/- 1.1 photons/msecond). For acute anterior uveitis, ARN, and pars planitis with CME, the inflammatory patterns were determined. The potential of laser flare-cell photometry for precise follow-up and adjustment of therapy was illustrated in cases of anterior and posterior uveitis. CONCLUSION: The authors' findings show that laser flare-cell photometry allows quantitative assessment of inflammation in uveitis and contributes to improved management of patients with uveitis.
Adolescent↗
Evaluation of port wine stains by laser Doppler perfusion imaging and reflectance photometry before and after pulsed dye laser treatment.
Treatment of choice for congenital capillary malformations of the port wine stain type is presently the pulsed dye laser. Although treatment results have usually been excellent or good, a few patients respond less well. Looking for a tool to predict and monitor the treatment we used laser Doppler perfusion imaging and reflectance photometry. Measurements with laser Doppler perfusion imaging were performed in 19 patients initially and after 1-3 treatments and with reflectance photometry initially and after 1-6 treatments. Before treatment, 15 of the patients had an increased bloodflow within the port wine stain in comparison with normal contralateral skin. After the laser treatments, 15 of 18 patients had decreased bloodflow within the lesion and all 18 had surrounding hyperemia. Reflectance photometry showed a successive increase in blanching and predicted within 6 weeks of the first treatment the eventual clinical result. The bloodflow, as measured with laser Doppler perfusion imaging, did not correlate well with the photometrically registered erythema. Reflectance photometry is a useful objective tool, which early in the treatment course indicates whether laser therapy will be successful. Laser Doppler perfusion imaging is less helpful in monitoring patients but may be of use in the study of port wine stain pathophysiology.
Adolescent↗
Ionometry versus flame photometry in dialysis therapy.
In order to decide whether the ionometer can be accepted as an alternative to the flame photometer in the measurement of sodium and potassium, extensive measurements with ionometry in parallel with flame photometry were performed in serum and dialysis fluid during dialysis. The influence of parameters which influence both ionometry and flame photometry in a different way (protein concentration, pH, acetate, and bicarbonate concentration) was investigated. The correlation between the two methods for potassium in serum and dialysis fluid was excellent (r greater than 0.95), but unsatisfactory for sodium in serum (r = 0.77) and in dialysis fluid (r less than 0.85). This low correlation is attributed in a greater extent to the random errors caused by flame photometry than by ionometry. Ionometry can be accepted as an alternative to flame photometry in dialysis therapy.
Evaluation Studies as Topic↗
Effect of cataract surgery with intraocular lens implantation on inflammation in chronic uveitis: a longitudinal laser flare photometry study.
BACKGROUND: The precise effect of cataract surgery with implantation of an intraocular lens (IOL) on the course of uveitis is not well known. Laser flare photometry allows quantitative assessment of intraocular inflammation. The aim of this study was to determine the effect of cataract surgery with IOL implantation on the disease course and level of inflammation in chronic uveitis, using laser flare photometry monitoring. METHODS: The charts of all patients who underwent surgery for secondary uveitic cataract between 1990 and 1994 (24/558 [4.3%]) were reviewed. Only eyes that had received standardized perioperative steroid treatment and had systematic laser flare photometry follow-up were included. Cataracts due to Fuchs' heterochromic cyclitis were excluded. Visual acuity, flare values and recurrence of flare episodes were compared before and after cataract surgery, and postoperative data were compared between eyes that received heparin-coated IOLs and those that received uncoated IOLs. RESULTS: Nineteen eyes of 16 patients met the inclusion criteria. The mean length of the pre- and- postoperative follow-up periods was 779 and 444 days respectively. The mean visual acuity increased from 0.2 (standard error of the mean [SEM] 0.2) preoperatively to 0.8 (SEM 0.3) postoperatively (p < or = 0.001). The mean flare value decreased from 58.6 (SEM 18.6) photons/ms during preoperative follow-up to 29.7 (SEM 7.8) photons/ms during postoperative follow-up (p < or = 0.006). The mean number of recurrences per 6 months decreased from 0.27 (SEM 0.03) preoperatively to 0.12 (SEM 0.01) postoperatively (p < or = 0.05). The difference in the postoperative recurrence rate between the eyes that received coated IOLs (0.0) and those that received uncoated IOLs (0.18 [SEM 0.02]) approached statistical significance (p < or = 0.054). INTERPRETATION: Quantitative assessment of inflammation by laser flare photometry in patients undergoing surgery for uveitic cataract showed that there was significantly less inflammation and fewer recurrences postoperatively and that recurrences were less severe.
Chronic Disease↗
Sensitivity of laser flare photometry to monitor inflammation in uveitis of the posterior segment.
PURPOSE: Laser flare photometry is a new quantitative method for evaluating aqueous flare, making flare the only inflammatory parameter that can be evaluated precisely and objectively. The validity of the method already has been demonstrated in anterior segment inflammation. The aim of this study is to assess the validity and limitations of the method to quantify and monitor inflammation in uveitis with predominant involvement of the posterior segment. METHODS: Five well-defined conditions with uveitis predominant in the posterior segment were analyzed in this study: Behçet uveitis, pars planitis, posterior sarcoidosis, posterior pole toxoplasmosis, and birdshot chorioretinopathy. (1) Mean initial (pretreatment) flare was determined; (2) in the patients needing systemic steroid therapy, introduction of therapy was correlated with evoluting laser flare photometry; and (3) in patients with quiescent disease, the predictive value of a defined subclinical photometry-detected flare rise for disease recrudescence was analyzed. RESULTS: Initial pretreatment flare was 331.8 +/- 47.7 photon counts per millisecond (ph/msecond) (mean +/- standard error of the mean) for Behçet uveitis, 15.6 +/- 1.3 ph/msecond for pars planitis, 26.9 +/- 4.6 ph/msecond for posterior sarcoidosis, 7.5 +/- 1.0 ph/msecond for posterior pole toxoplasmosis, 5.8 +/- 0.7 ph/msecond for birdshot chorioretinopathy, and 4.7 +/- 0.1 ph/msecond for a group of 88 control eyes. A significant flare reduction after start of steroid therapy was seen in Behçet uveitis (78% reduction), sarcoidosis (44.8%), and pars planitis (51%), but not in toxoplasmosis or in birdshot. A small flare rise had a predictive value for disease recrudescence in 27/35 patients (predictive value, 0.77; sensitivity rate, 100%). The level of associated blood-aqueous barrier disruption for reliable follow-up of posterior uveitis was empirically determined to be 13 to 15 ph/msecond. CONCLUSION: Laser flare photometry was found to be very sensitive to monitor inflammation in uveitis of the posterior segment as long as a sufficient level of associated blood-aqueous barrier disruption (flare) was present.
Adult↗
The physiological basis of heterochromatic flicker photometry demonstrated in the ganglion cells of the macaque retina.
1. Heterochromatic flicker photometry is a way of measuring the spectral sensitivity of the human eye. Two lights of different colour are sinusoidally alternated at, typically, 10-20 Hz, and their relative intensities adjusted by the observer until the sensation of flicker is minimized. This technique has been used to define the human photopic luminosity, or V lambda, function on which photometry is based. 2. We have studied the responses of macaque retinal ganglion cells using this stimulus paradigm. The responses of the phasic ganglion cells go through a minimum at relative radiances very similar to that predicted from the V lambda function. At this point, defined as equal luminance, an abrupt change in response phase was observed. A small residual response at twice the flicker frequency was apparent under some conditions. 3. The spectral sensitivity of parafoveal phasic cells measured in this way corresponded very closely to that of human observers minimizing flicker on the same apparatus. 4. Minima in phasic cell activity were independent of flicker frequency, as is the case in the psychophysical task. 5. The response minima of phasic cells obey the laws of additivity and transitivity which are important characteristics of heterochromatic flicker photometry. 6. As the relative intensities of the lights were altered responses of tonic, spectrally opponent cells usually underwent a gradual phase change with vigorous responses at equal luminance. The responses of tonic cells treated individually or as a population could not be related to the V lambda function in any meaningful way. 7. We conclude that the phasic, magnocellular cell system of the primate visual pathway underlies performance in the psychophysical task of heterochromatic flicker photometry. It is likely that other tasks in which spectral sensitivity conforms to the V lambda function also rely on this cell system.
Action Potentials↗
The use of high resolution microscope photometry in the discrimination of chromosome bands.
High resolution microscope photometry was used to discriminate between regions of differing density along the length of a banded metaphase chromosome. It has been demonstrated that photometry can be performed on such material to give a higher level of effective resolution than has hitherto been obtained. Using conventional visible light microscope photometry it is possible to obtain useful comparative densitometric information from measurements performed at a point separation equivalent to 0.05 micrometer in the object plane. The practical details of the equipment employed and the theoretical basis of the study are discussed.
Chromosome Banding↗
Heterochromatic modulation photometry.
Heterochromatic modulation photometry is a method for obtaining equiluminance for a pair of heterochromatic lights presented in temporal alternation. A series of fixed standard luminance/test luminance ratios are presented, and at each ratio the modulation depth of the pair is reduced in tandem until the observer reports that flicker disappears. The data can be described by a luminance contrast template that appears V shaped when plotted on log-log coordinates. In the fitting of individual data, a free vertical scaling factor reflects the observer's sensitivity to luminance modulation and a free horizontal scaling factor reflects the observer's similarity in spectral sensitivity to the CIE standard observer. Data for red/green flicker photometric matches demonstrate the technique. Heterochromatic modulation photometry offers several advantages over flicker photometry: (1) a single fixed perceptual transition occurs on each trial series, namely, the transition from flicker to steady, and (2) luminance matches can be obtained at fixed frequencies at a number of luminance levels. The same procedure can be applied to the measurement of the minimally distinct border and to the identification of tritan pairs (stimulus pairs that differ only in their stimulation of short-wavelength-sensitive cones).
Adult↗
Decalcification end point determination by X-rays and flame photometry to obtain superior quality pulpal sections.
Radiography and flame photometry have been compared as means of determining the end point of decalcification in relation to minimizing pulp-dentin separation in histological sections of teeth. Eighteen homologous pairs of vervet monkey incisor teeth were decalcified in a formic-citric acid mixture. At 24 hr intervals decalcification was monitored in half of the teeth by radiography and in the other half by flame photometry. When decalcification was complete as determined by the respective methods, histological specimens were prepared and separation at the pulp-dentin interface evaluated in hematoxylin and eosin stained step serial sections. The median separation was determined for the combined group and the median test applied. There was significantly less separation in the flame photometry group and within each group significantly less separation on the side where the knife cut from dentin to pulp.
Animals↗
Ektachem slides for direct potentiometric determination of sodium in plasma: effect of natremia, blood pH, and type of electrolyte reference fluid on concordance with flame photometry and other potentiometric methods.
With electrolyte reference fluid (ERF)00, results from Kodak Ektachem slides for the direct potentiometric assay of sodium in plasma were significantly correlated with results from flame photometry, but also appeared to be systematically higher, especially in hypernatremic patients. Indirect potentiometry with the Technicon RA-1000 yielded intermediate values. In 23 hypernatremic patients with greater than or equal to 6 mmol/L difference in sodium between Ektachem ERF00 and flame photometry, a clinical survey disclosed the frequent association of large between-method differences with renal failure, diabetes mellitus, and gastrointestinal disease. However, there was no correlation between differences in sodium on the one hand and anion gaps or (lipo)protein concentrations on the other, nor did in vitro addition studies implicate metabolites that often accumulate in the above-mentioned disorders. Unlike indirect methods, sodium measurements by direct potentiometry on Ektachem and Corning were influenced by in vitro changes of pH between 7.0 and 7.9. However, in a group of patients that included many acidotic individuals, between-method differences in sodium appeared not significantly correlated with in vivo blood pH. Use of the equitransferant ERF04 on Ektachem strongly diminishes the systematic differences with flame photometry, reduces the pH-dependency of the results to that of the direct Corning method, and brings the mean analytical recovery of sodium to below 95% (instead of 115% previously) without affecting the ability of Ektachem slides to avoid spuriously low results in the presence of increased (monoclonal) protein concentrations.
Blood↗
Endothelial precipitates and laser flare photometry in patients with acquired immunodeficiency syndrome: a screening test for cytomegalovirus retinitis?
Patients with acquired immunodeficiency syndrome (AIDS) who present with cytomegalovirus (CMV) retinitis show pathognomonic endothelial precipitates suggestive of primary anterior uveitis or secondary changes due to a spill-over from the posterior chamber. Laser flare photometry allows quantification of the intensity of anterior affection. We wanted to establish anterior-chamber flare values in AIDS patients with and without CMV retinitis and to find out whether CMV retinitis is preceded by an elevation of the flare value. In all, 25 men with AIDS who presented with CMV retinitis and 27 who did not have CMV retinitis but showed a CD4 count of < or = 200 cells/microliter blood were enrolled in a prospective study. Slit-lamp examination was performed, followed by indirect ophthalmoscopy and laser flare photometry after dilation of the pupil with tropicamide eye drops. Patients with CMV retinitis were followed every 10 days and the others, every 4 weeks. A group of 51 human immunodeficiency virus (HIV)-negative men served as a control group. AIDS patients with CMV retinitis showed a significantly higher flare count in the affected eye (12.4 photons/ms; n = 26) as compared with the unaffected partner eye (4.2 photons/ms; P < or = 0.0001; n = 18) and with eyes of AIDS patients without CMV retinitis (4.1 photons/ms; P < or = 0.0001; n = 50). The count in the latter eyes was also significantly higher than the control value (3.1 photons/ms; P < or = 0.0001; n = 102). Typical reticulate endothelial precipitates were found in 92% of AIDS patients with CMV retinitis. During the study, five eyes of three patients developed a fresh CMV retinitis, but a preceding rise in the flare count was not observed. Laser flare photometry follows the occurrence of pathognomonic reticulate endothelial precipitates. It lags behind the development and the extension of CMV retinitis. Therefore, it cannot be used as a screening test for early detection of CMV retinitis.
AIDS-Related Opportunistic Infections↗
Comparison of an inductively coupled plasma-atomic emission spectrometry method for the determination of calcium, magnesium, sodium, potassium, copper and zinc with atomic absorption spectroscopy and flame photometry methods.
Serum calcium, magnesium, copper and zinc concentrations obtained from the analysis of 77 serum samples by inductively coupled plasma-atomic emission spectrometry (ICP-AES) are compared with the results obtained using atomic absorption spectroscopy (AAS). Similarly, serum sodium and potassium levels from the analysis of the same samples by ICP-AES are compared with the levels obtained by flame photometry. For each metal, we compare the results from both methods with a linear regression program that assumes error in both variables. The regression analysis shows that the ICP-AES method gives slightly higher calcium, copper, and zinc results and lower magnesium results than the AAS methods, and lower sodium and potassium results than the flame photometry method. Except for sodium, the correlation (r) between the results is very high (greater than or equal to 0.958), indicating that the ICP-AES results could be corrected to be equivalent to the atomic absorption or flame photometry results. The ICP-AES has the advantage of requiring less preparation and analysis time, and additional elements could be determined simultaneously in the same sample.
Blood Specimen Collection↗
Measurements of sodium and potassium in newborns and prematures by ion-selective electrodes and flame photometry: influence of lipid and protein content of blood.
The alternative use of flame photometry and ion selective electrodes for electrolyte determinations in neonatology led to the question how the two methods agree. 104 routine blood samples were taken as matched pairs for a comparison of sodium and potassium determinations. Pre-analytical error was avoided by the mode of blood collection. The influence of the protein and lipid content of blood on the differences between the methods was determined by calculating its water content and making a post-correction of the flame values. Thus the differences for sodium could be reduced, whereas the differences for potassium slightly increased. As long as the imprecision of sodium determination is a meaningful methodological problem, the influence of the protein and lipid content of neonatal blood is not the main factor for differences between ISE and flame photometry.
Bilirubin↗
Evaluation of biangular reflection photometry for quantitative study of etched alloy surface roughness.
Biangular reflection photometry was correlated with quantitative stereology and direct pit-depth measurements for an electrolytically etched nickel-chromium-beryllium alloy. Effects of viewing angle, viewing aperture, and plane polarization of incident and viewing light were also studied. The results showed that architectural changes in the etched metal surface could be quantitatively described with the use of reflection photometry. An off-specular peak, located at an angle of reflection considerably different from the angle of incidence, was observed to have an intensity comparable with that of the specular reflection peak. Viewing aperture was found to affect one's ability to distinguish among degrees of surface roughness.
Acid Etching, Dental↗