PubMed · 11821179
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Emanuel S Rosen. 2002. Quantify.. https://doi.org/10.1016/s0886-3350(01)01326-8
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PURPOSE: To report the reliability of the glaucoma disk damage likelihood scale (DDLS) in comparison to the Armaly cup/disk ratio by determining the interobserver and intraobserver agreement for optic disk stereo photographs and the interobserver agreement for in vivo patient measurements of the optic disk. DESIGN: Observational case series. METHODS: Optic disk photographs: 48 stereo pairs of optic nerve photographs were selected from patients with a spectrum of glaucomatous visual field loss. Two masked observers graded the optic disk photographs three times according to the DDLS and Armaly cup/disk ratio. Interobserver and intraobserver agreements were calculated using the test-retest method. Patient measurements: three observers performed in vivo patient measurements on 34 eyes of glaucoma clinic patients and made a single determination of the DDLS stage and Armaly cup/disk ratio, based on the indirect biomicroscopic examination. Level of interobserver agreement was tabulated. RESULTS: Optic disk photographs: interobserver and intraobserver agreement for the vertical DDLS measurement was greater than for two determinations (clinical impression and measured) of the vertical Armaly cup/disk ratio (interobserver: 85% vs 68% and 74%, respectively; intraobserver grader 1: 97% vs 89% and 80%, grader 2: 99% vs 95% and 89%, respectively). In vivo patient measurements: the interobserver agreement for the DDLS and Armaly cup/disk ratio was similar (70.1% vs 67.6%, respectively). CONCLUSIONS: For the stereo optic disk photographs, the inter- and intra-observer agreement for the DDLS is greater than the Armaly cup/disk ratio. For the in vivo patient measurements, the level of agreement for the DDLS and the Armaly cup/disk ratio is similar.
OBJECTIVE: To evaluate changes in pupil size (corresponding to neuronal firing) within different time windows of the pupil light reflex in patients and normal subjects to understand which segments of the pupil waveform are best able to differentiate normal from abnormal subjects. DESIGN: Comparative, observational case series. PARTICIPANTS: Forty-nine normal subjects and 25 patients with known unilateral or asymmetric visual field damage were tested. METHODS: A dual-channel infrared pupillograph was used to simultaneously record the right and left pupil diameters at a rate of 60 Hz. Each eye was stimulated alternately (30 degrees full-field, 200 milliseconds duration every 3 seconds) over 10 different stimulus intensities. The recorded waveform of the pupil light reflex was subdivided into six time windows based on landmarks corresponding to contraction onset, maximum contraction velocity, peak contraction, and maximum dilation velocity to assess which portion was most affected by disease. MAIN OUTCOME MEASURES: The linear correlation between pupil contractions elicited by right versus left full-field stimulation at different light intensities provided diagnostic parameters (slope, intercept, and correlation coefficient R(2)) that were useful for differentiating normal subjects from patients and for categorizing disease. Sensitivity and specificity of the time windows were evaluated with receiver-operator curve analysis. RESULTS: The diagnosis of asymmetric disease was greatest at time windows that included pupil contraction but not dilation. When the contraction phase was subdivided into an early phase and into a late phase, the late phase was the most diagnostic compared with the entire phase of contraction amplitude (onset to peak contraction). CONCLUSIONS: By use of a range of light intensity, the change in pupil size measured between the time at which maximum contraction velocity occurs and the time to peak contraction provided the best response parameter for objective diagnosis of asymmetric disease of the anterior visual pathway. The waveform of the pupil light reflex may be an expression of the firing of retinal ganglion cells. Therefore, understanding which segment of the pupil light reflex provides maximal diagnostic power may give insight into how disease affects the pattern of neuronal firing rate.
In 1851 Helmholtz introduced the ophthalmoscope. The instrument allowed the observation of light reflected at the fundus. The development of this device was one of the major advancements in ophthalmology. Yet ophthalmoscopy allows only qualitative observation of the eye. Since 1950 attempts were made to address the challenging, quantitative assessment of the amount of light reflected by the fundus. At first, only comparative measurements were possible, applied in the study of macular and visual pigments. With improvements in light detecting techniques, and with the advent of microprocessors, the measurement of spectral and spatial distribution of the reflectance became feasible. This led to the development of models that explained the observed wavelength dependence and the directional behavior of light reflected from the fovea. The models allowed a quantitative assessment of many parameters on absorption and reflection by structures in the human eye. This paper provides a review of both the experimental and theoretical progress, and summarizes the results of fundamental and clinical research using fundus reflectometry.