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PubMed1978

Diseases of the optic nerve, tracts, and visual cortex: an annual review of the ophthalmic literature.

The ophthalmic literature dealing with diseases of the optic nerve, tracts, and visual cortex was reviewed for the period November 1976 to November 1977. Thirty-three papers of interest to optometrists have been abstracted. Main areas of interest include response of posterior segment to anterior-segment disturbances; structural anomalies in nerve-head region, including a new potential cause for hypoplasia of optic nerve; speculation on possible common origins of RPE/Bruch's membrane disturbances and endothelium/Descemet's membrane disturbances; a vascular hypothesis for pathogenesis of optic-nerve-head drusen; an explanation for reversibility of infantile glaucomatous cupping; glaucomatocyclitic crisis; the role of axoplasmic flow in papilledema; new developments in field testing for early glaucomatous loss; effects of cerebral vascular accidents on color vision; and two interesting instances of systemic disease with ocular manifestations.

Adolescent↗
PubMed2001

Evolution of activity patterns and chromatic vision in primates: morphometrics, genetics and cladistics.

Hypotheses for the adaptive origin of primates have reconstructed nocturnality as the primitive activity pattern for the entire order based on functional/adaptive interpretations of the relative size and orientation of the orbits, body size and dietary reconstruction. Based on comparative data from extant taxa this reconstruction implies that basal primates were also solitary, faunivorous, and arboreal. Recently, primates have been hypothesized to be primitively diurnal, based in part on the distribution of color-sensitive photoreceptor opsin genes and active trichromatic color vision in several extant strepsirrhines, as well as anthropoid primates (Tan & Li, 1999 Nature402, 36; Li, 2000 Am. J. phys. Anthrop. Supple.30, 318). If diurnality is primitive for all primates then the functional and adaptive significance of aspects of strepsirrhine retinal morphology and other adaptations of the primate visual system such as high acuity stereopsis, have been misinterpreted for decades. This hypothesis also implies that nocturnality evolved numerous times in primates. However, the hypothesis that primates are primitively diurnal has not been analyzed in a phylogenetic context, nor have the activity patterns of several fossil primates been considered. This study investigated the evolution of activity patterns and trichromacy in primates using a new method for reconstructing activity patterns in fragmentary fossils and by reconstructing visual system character evolution at key ancestral nodes of primate higher taxa. Results support previous studies that reconstruct omomyiform primates as nocturnal. The larger body sizes of adapiform primates confound inferences regarding activity pattern evolution in this group. The hypothesis of diurnality and trichromacy as primitive for primates is not supported by the phylogenetic data. On the contrary, nocturnality and dichromatic vision are not only primitive for all primates, but also for extant strepsirrhines. Diurnality, and possibly X-linked polymorphic trichromacy, evolved at least in the stem lineage of Anthropoidea, or the stem lineage of all haplorhines.

Animals↗
PubMed1992

[Early disorders of retinal function in diabetes mellitus].

Thirteen insulin-dependent diabetics, aged 13-30 (mean 19.15) years, entered the study. Patients with retinal ischemia, vascular proliferation, or a Snellen acuity below 0.8 were excluded. Ten normal untrained subjects, aged 20-30 (mean 24) years, provided the normal sample. The battery of special visual function tests consisted of: (1) high luminance Pflüger acuity (acuity/luminance/function, rotatable illiterate "E optotypes, screen luminance 10,000 cd/m2); (2) tests combining color vision with demands on spatial resolution: (a) blue-green chromatic acuity (a Velhagen pseudoisochromatic plate served as optotype, the maximum recognition distance being recorded); (b) standard vs mini-panel D-15 color-arrangement tests; (c) blue preferential computerized perimetry (modified Tübingen automatic perimeter, orange adaptive illumination, Schott cut-off filter OG 550, cupola luminance 5 cd/m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

New procedures for evaluating vision functions of special populations.

Research over the last few decades has demonstrated the rapid development of vision function that occurs in infancy with near-adult levels reached before the age of 1 year. This period of rapid development coincides with the period of maximum sensitivity to insult. These facts emphasize the importance of effective screening techniques for visual disorders. Off-axis photorefraction is described as a new and effective screening technique for detection of refractive errors, media opacities, and strabismus. Separate from screening, a significant need exists for optometric vision evaluations in special populations. Normal infants, developmentally delayed or multi-handicapped children and adults, and cognitively impaired adults are examples of special populations who are difficult to examine with standard optometric techniques. New procedures for measuring visual acuity, contrast sensitivity, color vision, and stereopsis using behavioral or electrophysiological measures are described. Advantages and disadvantages of the different techniques are discussed.

Color Perception↗
PubMed1994

[Increased threshold for detection of phase differences in pattern-induced color flicker fusion in patients with glaucoma].

BACKGROUND: Pattern-induced flicker-colors are subjective colors produced by rotating disks with black-and-white arcs. Changing the direction of rotation results in a different color. Small variations in the temporal sequence (phase differences) of the black-and-white pattern cause the colors to vary and can be perceived as color differences. PATIENTS AND METHODS: We investigated the thresholds for such phase differences in healthy (n = 11) and in glaucomatous (n = 19) eyes. Acuity and color vision were tested and in patients static visual field perimetry (Octopus G1) was carried out. The disks used for producing the pattern-induced flicker-colors were viewed from a distance of 2 m and had a luminance of 35 cd/m2. The phase difference thresholds were determined using a double staircase procedure. RESULTS: In glaucomatous eyes the thresholds were significantly higher (33.9 +/- 4.8 for clockwise rotation) than in normal eyes (18.2 +/- 1.4), p < 0.005 and this was the case for anticlockwise as well as clockwise rotation. The difference between the two groups remained significant (p < 0.025) when the data for glaucomatous eyes was corrected for acuity losses. CONCLUSIONS: In the glaucomatous eyes the increase in phase difference threshold was correlated with raised visual field MD (r = 0.87 for clockwise rotation). The higher thresholds in glaucomatous eyes point to a loss in blue-yellow-sensitive, parvocellular retinal ganglion cells, which play an important part in the perception of pattern-induced flicker-colors. Pattern-induced flicker-colors are a new method for the clinical investigation of retinal function in the center of the visual field and have the advantage that fixation is unnecessary and the yellow filter properties of the refractive media and the macula are of no importance.

Adolescent↗
PubMed2003

Review of the CIE system of colorimetry and its use in dentistry.

UNLABELLED: When we observe the light reflected from surfaces in a scene or look directly at light emitted by light sources, we experience the sensation of color. Color is just one attribute of a complex and not fully understood set of properties that define the appearance of our surroundings. To measure or specify the color of an object, we need to take into account the nature of the light under which the object is viewed, the spectral reflectance properties of the surface, and the properties of the human color vision system. CLINICAL SIGNIFICANCE: In this article the CIE system of colorimetry is briefly reviewed and its limitations are described. The consequences of these limitations for color measurement in dentistry are discussed.

Algorithms↗
PubMedDate not supplied

[Protective sunglasses and color discriminating ability].

The influence on color vision of 4 kinds of sun-glasses with various characteristics of transparency and absorption of 25, 50, 75 p.c. was evaluated. Sixty persons with normal color discrimination took part in investigation. The selection of filters for professional drivers and railway engine-drivers was performed on the basis of Nagel's anomaloscope and Farnworth-Munsell's 100--Hue tests.

Adolescent↗
PubMed1991

Separate processing of "color" and "brightness" in goldfish.

Spectral sensitivity was measured under different adaptation levels using a behavioral training technique in which the fish had to discriminate between a dark test field and a test field illuminated with monochromatic light. Depending on which of the two test fields was used as training test field, two functions were obtained which differ (1) in absolute sensitivity and (2) in shape. When trained on the dark test field, the fish seems to discriminate on the basis of a "color" cue, but it uses a "brightness" cue when trained on the illuminated test field. This was concluded from measurements of wavelength discrimination. Under low levels of the adaptation light (1.5 and 0.2 lx instead of 20 lx), the L-cone type contributes to perception of "brightness" but not to color vision. This difference in the adaptation behavior in the long-wavelength range was used to identify the ganglion cells which may represent channels for "brightness" and "color" in the retina. Action spectra were recorded extracellularly at different levels of dark- and light-adaptation.

Animals↗
PubMed1999

Color schemes to represent the orientation of anisotropic tissues from diffusion tensor data: application to white matter fiber tract mapping in the human brain.

This paper investigates the use of color to represent the directional information contained in the diffusion tensor. Ideally, one wants to take into account both the properties of human color vision and of the given display hardware to produce a representation in which differences in the orientation of anisotropic structures are proportional to the perceived differences in color. It is argued here that such a goal cannot be achieved in general and therefore, empirical or heuristic schemes, which avoid some of the common artifacts of previously proposed approaches, are implemented. Directionally encoded color (DEC) maps of the human brain obtained using these schemes clearly show the main association, projection, and commissural white matter pathways. In the brainstem, motor and sensory pathways are easily identified and can be differentiated from the transverse pontine fibers and the cerebellar peduncles. DEC maps obtained from diffusion tensor imaging data provide a simple and effective way to visualize fiber direction, useful for investigating the structural anatomy of different organs. Magn Reson Med 42:526-540, 1999.

Anisotropy↗
PubMed1977

The office retinal electrophysiology laboratory.

The "Visual Retinal Profile" can be obtained in the complete office evaluation of patients with night vision disorders, unexplained poor visual acuity, or undiagnosed retinal and/or choroidal diseases. This profile allows later follow-up evaluations and comparisons of previous tests to document improvement or progression of disease. The profile consists of the usual ophthalmologic evaluation plus color vision testing Amsler grid, stereoacuity, visual fields, electroretinogram (ERG), and electrooculogram (EOG). This entire set of tests, though time consuming, can be performed in the office by an ophthalmic assistant and greatly add to the ophthalmologists ability to evaluate and diagnose subtle retinal and/or choroidal diseases. A portable ERG/EOG and light source will be described that can be used in the office, clinic, nursing home, or operating room by trained office personnel.

Choroid↗
PubMed1997

Colour vision through intraocular lens.

Fifty patients aged from 30 to 69 years (mean 54.7 +/- 11.3 years, SD) with a UV-protected monofocal polymethylmethacrylate intraocular lens (IOL) were examined with the Farnsworth-Munsell 100 hue (FM 100) test and the Color Vision Meter 712 anomaloscope. The spectral transmission of the same kind of IOLs as was used surgically was measured with Lambda 2 UV/VIS Spectrometer. In the FM 100 test, there was no significant difference between the results of the IOL eyes and normal eyes. However, the IOL eyes showed better error scores than the normal eyes in the blue-purple box IV in the FM 100 test. In the anomaloscope testing, the Rayleigh (red-green) equation showed no differences between the IOL patients and controls. In the Moreland (blue) equation, however, the mid matching point was significantly shifted towards more green (meaning better blue colour sensitivity) in the IOL eyes than in the control eyes. This is due to the spectral transmission of the IOLs which showed 80-90% transmission already starting at the wavelength of about 420 nm. In comparison, the transmission of the normal human lens reaches those percentages near 500 nm or even further at advanced age.

Adult↗
PubMed1998

Color discrimination in patients with keratoconjunctivitis sicca before and after artificial tear application.

BACKGROUND: The precorneal tear film is of decisive importance for the optical quality of the cornea. Poor stability of this film causes not only dry eye symptoms, but also has negative effects on optical functions of the eye, as previous studies on visual acuity, field test performance and contrast sensitivity have shown. METHODS: 60 patients with dry eyes randomized into 2 groups of 30 underwent color vision testing with the Lanthony Desaturated 15 Hue test before and after instillation of artificial tear (test group) or physiological saline (control group) drops. RESULTS: The improvement in color discrimination in the group given artificial tear treatment was found to be slightly better than in the saline group but in both groups this improvement was not of statistical significance. CONCLUSION: Even though an unstable tear film adversely affects the optics of the eye and even mildly degraded optics can affect spatial visual tasks, color discrimination performance on tasks such as the Lanthony D-15 test does not appear to be markedly impaired.

Adult↗
PubMed1978

Color-naming evidence for tritan vision in the fovea.

A color-naming task was used to assess color vision in the fovea and parafovea. Like traditional psychophysical procedures, color naming showed that short-wavelength vision is suppressed centrally. The anatomical and physiological mechanisms underlying tritan foveal vision are discussed.

Adolescent↗
PubMedDate not supplied

Visual functions of drivers involved in traffic accidents.

Eye functions were studied in 56 drivers who had recently been involved in traffic accidents. There were 17 women and 39 men in the study group, aged 20-87 years. The traffic accidents had happened in intersections and city streets, in parking places and on highways. In seven drivers, a visual impairment was found: two drivers had strabismus and low visual acuities in one or both eyes, two had considerable hyperphoria, and three had a deutan color vision defect. However, comparing the type of accident to the defective eye functions showed no probable correlation.

Accidents, Traffic↗
PubMed2002

Impact of graphical user interface screen features on computer task accuracy and speed in a cohort of patients with age-related macular degeneration.

PURPOSE: To investigate the impact of graphical user interface screen features on computer task performance in patients with age-related macular degeneration (AMD). DESIGN: Interventional case series. METHODS: Eighteen patients with visual impairment due to AMD were recruited from the Bascom Palmer Eye Institute Low Vision Clinic. Each patient underwent evaluation of visual acuity using the Early Treatment Diabetic Retinopathy Study protocol, contrast sensitivity using a Pelli-Robson chart, binocular simultaneous visual field using the Esterman program on an automated perimeter, and color vision using Farnsworth D-15. Each subject then completed computer icon identification tasks while the following screen features of the graphical user interface were varied: size of icons displayed, icon set size (number of icons displayed), and background color. Each patient performed all 125 computer tasks with each of five icon sizes (9.2 mm, 14.6 mm, 23.2 mm, 36.8 mm, 58.3 mm), each of five icon set sizes (2, 3, 4, 5, 6), and each of five different background colors (black, white, red, green, blue) in a randomly ordered fashion. Relationships between computer task performance (accuracy and speed) and graphical user interface screen features were studied. RESULTS: Icon size and icon set size are significantly associated with computer task accuracy (P <.001), whereas background color is not a significant predictor of task accuracy (P =.63). The impact of icon size on accuracy is nonlinear, with the data indicating that no additional improvement in accuracy is associated with increasing the icon size beyond 23.2 mm. The impact of icon set size on accuracy is linear, with a smaller icon set size significantly associated with greater computer accuracy. A larger icon size is significantly associated with a shorter time to task completion (P =.001); this relationship is largely linearly related to icon size. There was no significant impact of background color (P =.11) or set size (P =.37) on time to task completion. CONCLUSIONS: Modifications of graphical user interface design may permit improved computer task performance among patients with visual impairment due to AMD.

Adult↗
PubMed1994

Electrophysiological measurements of spectral mechanisms in the retinas of two cervids: white-tailed deer (Odocoileus virginianus) and fallow deer (Dama dama).

Electroretinogram (ERG) flicker photometry was used to study the spectral mechanisms in the retinas of white-tailed deer (Odocoileus virginianus) and fallow deer (Dama dama). In addition to having a rod pigment with maximum sensitivity (lambda max) of about 497 nm, both species appear to have two classes of photopic receptors. They share in common a short-wavelength-sensitive cone mechanism having lambda max in the region of 450-460 nm. Each also has a cone having peak sensitivity in the middle wavelengths, but these differ slightly for the two species. In white-tailed deer the lambda max of this cone is about 537 nm; for the fallow deer the average lambda max value for this mechanism was 542 nm. Deer resemble other ungulates and many other types of mammal in having two classes of cone pigment and, thus, the requisite retinal basis for dichromatic color vision.

Animals↗
PubMed1984

Color contrast perimetry.

A method for color perimetry is proposed in which colored test objects are presented in a white surround, so that the luminance of the object and its surround are identical. The color of the test object then may be varied in its degree of saturation, while maintaining a constant luminance. A color video instrument controlled by a microcomputer is used as a tangent screen. Foveally viewed, colored test objects are adjusted initially in luminance by heterochromatic flicker photometry to match the luminance of a white background at 100 apostilb. The relative foveal scotoma for blue light requires that test objects large enough to include the perifoveal retina be used for flicker photometry of blue test objects. Due to the progressively increasing threshold for luminance contrast detection in extrafoveal retina, differences in luminance between the colored objects and the white surrounding, as the test objects are moved into the extrafoveal visual field, appear to remain subthreshold. Test object detection can thus be expected to be a perimetric measure of color contrast detection, relatively unaffected by luminance contrast detection. This strategy should simplify the use of colored objects for clinical perimetric testing and should provide a specific test of color vision in the extrafoveal visual field.

Adult↗
PubMed2003

Unilateral visual loss after cervical spine surgery.

This is a case report of a patient who underwent an uneventful surgery for atlanto-axial dislocation in the prone position, after which he developed painless, unilateral loss of vision in the immediate postoperative period. Based on the ophthalmologic findings a probable diagnosis of ischemic optic neuropathy (ION) was made. Although he recovered his visual acuity completely in 1 month, the visual field defects and color vision abnormalities persisted. Intraoperative anemia, hypotension, with or without vasculopathic risk factors, and prolonged surgery in the prone position have been reported as major risk factors for the development of this complication following spine surgery. However, this healthy young man had an uneventful surgery with no such intraoperative complications. ION in this patient could have been due to a combination of factors, such as a malpositioned horseshoe headrest and surgery performed in the prone position, both of which have the potential to raise the intraocular pressure and lower the perfusion pressure of the optic nerve/nerve head. Variations in the blood supply of the optic nerve due to the presence of watershed zones could be another explanation for this dreaded complication.

Adult↗

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