PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Eye Color”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources
PubMed1989

Somatic cell mutagenesis in Drosophila: recovery of genetic damage in relation to the types of DNA lesions induced in mutationally unstable and stable X-chromosomes.

This paper reports the results of a study on the genotoxic activities of 12 mutagens and clastogens of widely differing mode of action in somatic cells in vivo, i.e., in the eye primordia of Drosophila larvae. After emergence, adult flies were monitored for aberrantly colored sectors in the compound eyes of the following genotypes: UZ males and females (zeste) carrying a genetically unstable transposable element, SZ males and females (zeste) carrying a partial duplication of the w+ locus plus a transposon insert, white-coral/white (wco/w) females, w+/w females and w+ males. The UZ and SZ marker sets make it possible to monitor shifts from zeste to red (scored as mosaic red spots, RS) and for loss of the white locus (light spots, LS). wco/w+ females were scored for mosaic twin spots (TS) and LS, w+ genotypes for just LS. The genotoxins analyzed were methyl methanesulfonate (MMS), dimethyl sulfate (DMS) and ethylnitrosourea (ENU) (alkylating), adriamycin (AM) and daunomycin (DM) (intercalating), Trenimon, Thio-TEPA and cisplatin (DDP) (cross-linking), bleomycin (strand-breaking), 7,12-dimethylbenz[a]anthracene (DMBA) and 9,10-dimethylanthracene (DA) (bulky monoadducts) and cytosine arabinofuranoside (inhibition of DNA synthesis). The relative mutabilities with frequencies of mosaic light spots (LS) in w+/w female as the standard (relative mutability = 1) vs. genotypes UZ (RS in male) vs. SZ (RS in male) vs. w+ (LS in male) were 1:0.6:0.2:0.3 for MMS, 1:0.09:0.05:0.7 for DDP, and 1:1.6:0.2:1.0 for ENU, ENU showed exceptional behavior in that it was the only compound for which mutational response, measured by the induction of red spots, was highest with the UZ marker set. Occurrence of large light spots (LS) in male but not in female genotypes was negatively correlated with efficiency of agents for chromosomal damage, suggesting that in the hemizygous condition, as in males, selection of damaged cells and mitotic delay may have played a significant role. In general, the results indicate that there is no association between the ability of an agent to act as a clastogen and the recovery of aberrant (red spots) sectors in either the UZ or the SZ strain, and of single light spots (LS) in w+, UZ and SZ males. The possibility is considered that the process causing the genetic instability in the UZ strain is under genetic control, and that strong point mutagens such as ENU through efficient gene mutation induction can interfere with it.

Animals↗
PubMed1994

Eye movements and the associative basis of contingent color aftereffects: a comment on Siegel, Allan, and Eissenberg (1992).

One of S. Siegel, L. G. Allen, and T. Eissenberg's (1992) recent arguments in support of associative-learning explanations of colored aftereffects (CAEs) is that the contingencies underlying these effects are not constrained by simple stimulus dimensions, such as contour orientation. Specifically, the authors claim to have generated CAEs contingent on sets of spatiotopic relationships between orientation components of a pattern (as opposed to orientation components per se). The present article illustrates how Siegel et al.'s claims are compromised by their failure to adequately address the role of fixation and eye movements during CAE induction.

Adolescent↗
PubMed1993

[Computerized image analysis in the glaucomatous optic disc color changes].

The disc rim color changes in 40 eyes with primary open angle glaucoma (POAG) were studied using a computerized color analysis system. Optic disc color was evaluated by quantification of the red ratio based on the analyzed level of red, green, and blue elements. The correlation among the changes in neuroretinal rim color, visual field and cup area to disc area ratio (C/D.A) was evaluated. In 18 eyes in the early stage, with total initial loss less than 100 dB, the disc color change correlated with both mean sensitivity decrease (Pearson's r = 0.7410, p = 0.0004) and C/D. A increase (Pearson's r = 0.4698, p = 0.0492). In 22 eyes in the middle stage with total initial loss over 100 dB, the disc color variation correlated with mean sensitivity loss (Pearson's r = 0.7503, p < 0.0001) but not with C/D. A (Pearson's r = 0.2980, p = 0.1780). Neuroretinal rim color changes correlated with the value of mean sensitivity loss at any stage of POAG. These results suggest that neuroretinal rim color change in eyes at an early stage depend on a different histological change from that in the middle stage in POAG.

Color↗
PubMed1989

Double-flash electroretinography in human eyes.

A tri-color Ganzfeld stimulator with light-emitting diodes as light sources is used to study the suppression of the second electroretinographic response in human eyes to double-flash stimulation. The mechanism suppressing the a- and b-waves of the response to the second (test) flash has a scotopic spectral sensitivity to the first (conditioning) flash. Responses to mild test stimuli are more sensitive to suppression by a conditioning flash than responses to strong test stimuli.

Color Perception↗
PubMed2002

Colour in the eyes of insects.

Many insect species have darkly coloured eyes, but distinct colours or patterns are frequently featured. A number of exemplary cases of flies and butterflies are discussed to illustrate our present knowledge of the physical basis of eye colours, their functional background, and the implications for insect colour vision. The screening pigments in the pigment cells commonly determine the eye colour. The red screening pigments of fly eyes and the dorsal eye regions of dragonflies allow stray light to photochemically restore photoconverted visual pigments. A similar role is played by yellow pigment granules inside the photoreceptor cells which function as a light-controlling pupil. Most insect eyes contain black screening pigments which prevent stray light to produce background noise in the photoreceptors. The eyes of tabanid flies are marked by strong metallic colours, due to multilayers in the corneal facet lenses. The corneal multilayers in the gold-green eyes of the deer fly Chrysops relictus reduce the lens transmission in the orange-green, thus narrowing the sensitivity spectrum of photoreceptors having a green absorbing rhodopsin. The tapetum in the eyes of butterflies probably enhances the spectral sensitivity of proximal long-wavelength photoreceptors. Pigment granules lining the rhabdom fine-tune the sensitivity spectra.

Animals↗
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↗
PubMedDate not supplied

Evaluation of hemodynamic changes in the ophthalmic artery with color Doppler ultrasonography after strabismus surgery.

PURPOSE: To investigate the blood flow changes in ophthalmic artery with color Doppler ultrasonography after strabismus surgery. METHODS: Twenty eyes of 19 patients who underwent recession or resection surgery on two horizontal rectus muscles in 1 eye were examined using color Doppler ultrasonography preoperatively and 1 week and 1 month postoperatively. Measurements from both eyes of 16 age- and sex-matched normal subjects served as control data. The systolic maximum velocity, mean velocity, end-diastolic velocity, pulsatility index, and resistance index of the ophthalmic artery were determined. The Mann-Whitney U test was performed for comparison of the control and study group preoperatively for any hemodynamic parameter. Statistical comparison of the preoperative and postoperative measures in the study group was performed with Friedman's two-way analysis of variance. RESULTS: No difference (P>.05) was observed preoperatively between the study and control groups for any hemodynamic parameter in the ophthalmic artery. Although the ophthalmic artery showed a slight increase in systolic maximum velocity 1 month postoperatively, there were no statistically significant differences (P>.05) in velocities or resistance in the ophthalmic artery at any interval. CONCLUSION: Two horizontal rectus muscle operations in a previously unoperated eye do not cause significant hemodynamic changes in the ophthalmic artery. However, further studies are needed to obtain more information about the effect of multiple vertical rectus muscle operations on the blood flow parameters of the ophthalmic artery.

Adolescent↗
PubMed1995

Melanogenesis by human uveal melanocytes in vitro.

PURPOSE: To study melanogenesis by cultured human uveal melanocytes, and the relationship between melanin production by uveal melanocytes in vitro with the degree of iris pigmentation in vivo. METHODS: Melanin content, melanin production, and tyrosinase activity of cultured uveal melanocytes derived from eyes of various iris color were measured at different stages of cultivation. RESULTS: Cultured uveal melanocytes maintained a constant level of melanin content, expressed tyrosinase activity, and produced measurable amounts of melanin in vitro. Melanosomes in different stages were seen ultrastructurally. Melanin production correlated directly with the degree of iris pigmentation of the eyes from which the uveal melanocytes were isolated. Tyrosinase activity of cultured uveal melanocytes from black versus white donors was significantly different, but, among white donors, there was no correlation with iris pigmentation or with melanin production in vitro. CONCLUSION: Cultured uveal melanocytes can produce melanin in vitro. Cultured uveal melanocytes isolated from eyes of different iris color maintained their inherent capacity for melanogenesis. Therefore, cultured uveal melanocytes are an excellent model system for studying melanogenesis in uveal melanocytes in vitro.

Black People↗
PubMed1994

Analysis of crystalline lens coloration using a black and white charge-coupled device camera.

To analyze lens coloration in vivo, we used a new type of Scheimpflug camera that is a black and white type of charge-coupled device (CCD) camera. A new methodology was proposed. Scheimpflug images of the lens were taken three times through red (R), green (G), and blue (B) filters, respectively. Three images corresponding with the R, G, and B channels were combined into one image on the cathode-ray tube (CRT) display. The spectral transmittance of the tricolor filters and the spectral sensitivity of the CCD camera were used to correct the scattering-light intensity of each image. Coloration of the lens was expressed on a CIE standard chromaticity diagram. The lens coloration of seven eyes analyzed by this method showed values almost the same as those obtained by the previous method using color film.

Cataract↗
PubMed1999

Color Doppler image of central retinal artery of eyes with an intraconal mass.

PURPOSE: Retinal ischemia secondary to hypoperfusion of the central retinal artery is recognized as one factor that may contribute to the development of loss of vision in eyes with intraorbital tumors. We study intraorbital tumors which produce motility disturbances and visual problems by color Doppler imaging to evaluate this factor. METHODS: We examined the central retinal artery velocities of 3 patients with disc edema caused by intraconal masses (2 cavernous hemangiomas and 1 presumed optic nerve glioma) via color Doppler imaging. RESULTS: The time-velocity waveform demonstrated abnormally high vascular resistance in the central retinal artery of all affected eyes in the primary position compared with the normal waveform seen in the other eyes. We compared the pulsatility index of eyes with an intraconal mass and contralateral, control eyes using Student's t test for paired samples and significant differences were noted between both groups (p< 0.01). CONCLUSIONS: Intraconal tumors could produce increased pressure in the optic nerve sheath and the optic nerve tissue which could be associated with impaired retinal and optic nerve blood flow and the subsequent amaurosis encountered with intraorbital tumors.

Adult↗
PubMed1987

Heritable somatic excision of a Drosophila transposon.

A mutation in the white gene of Drosophila mauritiana that results from insertion of the transposable element mariner is genetically unstable in both germ cells and somatic cells. Somatic instability is indicated by the occurrence of animals having mosaic eyes with patches of pigmented cells on a peach-colored background. Normally uncommon, the frequency of mosaicism is so greatly enhanced in a particular mutant strain that virtually every animal in the strain is an eye-color mosaic. The molecular basis of the mosaicism is the excision of the mariner element from its location in the DNA of the white gene in somatic cells. The phenomenon results from a single dominant genetic factor located in chromosome 3. Genetic control over the excision of transposable elements may play a role in determining the persistence of transposable elements in the genome.

Alleles↗
PubMedDate not supplied

Albino and pink-eyed dilution mutants in the Russian dwarf hamster Phodopus campbelli.

The coat color mutant genes albino (c) and pink eyed dilution (p) are described in the dwarf hamster species Phodopus campbelli. Both genes are inherited as redessive to normal. Tests for linkage between the two genes gave negative results. The apparent absence of linkage is contrasted with linkage between homologous alleles c and p in other species of rodents.

Albinism, Oculocutaneous↗