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PubMed1997

Prostaglandin-induced iridial pigmentation in primates.

Latanoprost, a new ocular hypotensive prostaglandin F2 alpha analogue prodrug, was found to induce increased pigmentation of monkey irides in chronic toxicity studies. This prompted us to investigate the effect of naturally occurring prostaglandins on the monkey iris to determine whether this pigmentary effect is unique for latanoprost or whether it is a class effect of prostaglandins. PGF2 alpha-isopropyl ester (IE), PGE2-IE and latanoprost were applied topically to cynomolgus monkey eyes for 18-44 weeks. One eye of each animal was treated, while the other served as control. In addition, latanoprost was applied to sympathectomized monkey eyes. PGF2 alpha-IE, PGE2-IE, as well as latanoprost, induced increased pigmentation in the monkey eye. The first signs of this effect were seen after about two months of treatment. Latanoprost also induced increased pigmentation in sympathectomized eyes. It is concluded that both naturally occurring prostaglandins and their synthetic analogues can induce increased iridial pigmentation in cynomolgus monkeys, and that the effect does not require the presence of sympathetic nerves.

Administration, Topical↗
PubMed2001

Cellular and hormonal regulation of pigmentation in human ocular melanocytes.

The purpose of this study was to examine some of the factors that may be relevant to regulating pigmentation in the human eye, specifically whether choroidal and iridial melanocytes are sensitive to regulation by epithelial and stromal cells and alpha-melanocyte stimulating hormone (alpha-MSH). Human choroidal and iridial melanocytes were established in culture and co-cultured with epithelial cells and stromal cells derived both from skin and from eye in order to determine their influence on choroidal and iridial melanocyte dopa oxidase activity. In all cases, co-culture of melanocytes with either epithelial cells or fibroblasts led to an increase in dopa oxidase activity during 5 days of co-culture. The extent of the increase ranged from 60% (non-significant) to as much as 185% when both fibroblasts and keratinocytes were present. The optimal ratio of fibroblasts to melanocytes was 1:10 (for dermal fibroblasts) or 1:2 (for iridial fibroblasts) and 1:1 for all epithelial cells to melanocytes. Both choroidal (three out of three cultures) and iridial (two out of three cultures) melanocytes showed increases in dopa oxidase activity to alpha-MSH when cultured in Green's media but the same cells cultured in MCDB153 were unresponsive to alpha-MSH. These in vitro studies suggest that ocular melanocytes have the capacity to be influenced by adjacent epithelial and stromal cells with respect to pigmentation.

Adult↗
PubMed1991

Transscleral cyclophotocoagulation of human autopsy and monkey eyes.

We studied the effect of uveal pigmentation on contact Nd:YAG transscleral cyclophotocoagulation in 36 human autopsy and eight cynomolgus monkey eyes. Ten autopsy eyes from black individuals required less energy to create a lesion than 23 eyes from whites. The mean lesion diameter at the posterior pars plicata was similar in all these eyes; however, the mean energy required was 4.4 J in the black and 6.4 J in the white eyes. Transscleral cyclophotocoagulation lowered intraocular pressure (IOP) in four monkey eyes with elevated IOP, but did not in four other eyes without elevated IOP. Treatment over conjunctival pigmentation burned the conjunctiva, even at the lowest energy tested (3.5 J). Contrary to other investigators' findings, transmission electron microscopy showed at least short-term loss of scleral architecture in both the human autopsy and monkey eyes.

Animals↗
PubMed2001

Susceptibility of proliferating cells to benzo[a]pyrene-induced homologous recombination in mice.

The pink-eyed unstable mutation, p(un), is the result of a 70 kb tandem duplication within the murine pink-eyed, p, gene. Deletion of one copy of the duplicated region by homologous deletion/recombination occurs spontaneously in embryos and results in pigmented spots in the fur and eye. Such deletion events are inducible by a variety of DNA damaging agents, as we have observed previously with both fur- and eye-spot assays. Here we describe a study of the effect of exposure to benzo[a]pyrene (B[a]P) at different times of development on reversion induction in the eye. Previously we, among others, have reported that the retinal pigment epithelium (RPE) displays a position effect variegation phenotype in the pattern of pink-eyed unstable reversions. Following an acute exposure to B[a]P or X-rays on the tenth day of gestation an increased frequency of reversion events was detected in a distinct region of the adult RPE. Examining exposure at different times of eye development reveals that both B[a]P and X-rays result in an increased frequency of reversion events, though the increase was only significant following B[a]P exposure, similar to our previous report limited to exposure on the tenth day of gestation. Examination of B[a]P-exposed RPE in the present study revealed distinct regions where the induced events lie and that the positions of these regions are found at increasing distances from the optic nerve the later the time of exposure. This position effect directly reflects the previously observed developmental pattern of the RPE, namely that cells in the regions most distal from the optic nerve are proliferating most vigorously. The numbers and positions of RPE cells displaying the transformed (pigmented) phenotype strongly advocate the proposal that dividing cells are at highest risk to deletions induced by carcinogens.

Animals↗
PubMed1994

Iris pigmentation and extent of disease in patients with neovascular age-related macular degeneration.

PURPOSE: To determine whether the extent of disease in age-related macular degeneration (AMD) varies with iris pigmentation. METHODS: The authors assessed visual function and macular appearance in the fellow eye or both eyes of 132 white patients with unilateral neovascular AMD. All patients had a visual acuity of 20/60 or better in the fellow eye. Eighty-nine of the patients were coded as having light irides (blue, green, or hazel) and 43 were coded as having dark irides (brown); the two groups of patients had comparable mean ages. RESULTS: By the Mann-Whitney test for differences in mean rank, fellow eyes with light irides showed a marginally worse visual acuity (P = .156) but significantly more visual field impairment by letter recognition perimetry (P = .011) and the macular threshold test of the Humphrey Field Analyzer (P = .043), and more retinal pigment epithelial atrophy (P = .017) and focal areas of hyperpigmentation (P = .002) than fellow eyes with dark irides. For eyes with a choroidal neovascular membrane (CNVM), those with light irides had significantly lower visual acuities (P = .006) and larger scars (P = .006) than eyes with dark irides. In addition, extent of disease in the eye with a CNVM was positively correlated with extent of disease in the fellow eye for most comparisons. CONCLUSIONS: These observations suggest that light iris pigmentation is associated with more extensive retinal disease in patients with unilateral neovascular AMD. Furthermore, in such patients, those with worse disease in the eye with a CNVM may tend to have more extensive atrophic disease in the fellow eye.

Aged↗
PubMed1984

Iris color and hearing loss.

This study investigated the relation between iris color and hearing loss in 261 adult textile workers exposed to either a low-noise environment (below 85 dB) or a high-noise environment (above 102 dB). The subjects included 48% white males, 28% white females, 15% black males, and 9% black females. No relation was found between iris color and hearing loss in the control or low-noise group. A significant relation between iris color and hearing loss or hearing threshold levels was found for workers in the high-noise environment. Other variables, however, were found to predict susceptibility to hearing loss better than iris color alone.

Adolescent↗
PubMed1998

The influence of iris color on the pupillary light reflex.

BACKGROUND: This study was carried out to investigate the effect of iris color on the pupillary light reflex (PLR) in normal healthy volunteers. METHODS: Pupil perimetry was performed on 50 healthy volunteers with the Octopus 1-2-3 automated perimeter. Within the 30-deg visual field, 33 test locations were investigated four times. Stimulus parameters were Goldmann size V (1.72 degrees), intensity 1632 cd/m2, stimulus time 200 ms, background illumination 0 cd/m2, and interstimulus interval 3 s. Pupillometric parameters studied were initial pupil size, amplitude (magnitude of pupillary contraction), latency time, contraction time, pre-PLR movement, contraction velocity, and redilation velocity. Pupillometric parameters were investigated by analysis of variance by the independent variables blue and brown irides. RESULTS: Iris color (blue vs brown) influenced statistically significantly (P < 0.05) amplitude (0.504 mm vs 0.594 mm), contraction time (401 ms vs 407 ms), contraction velocity (13.75 mm2/s vs 16.01 mm2/s), and redilation velocity (4.80 mm2/s vs 5.66 mm2/s). Iris color did not influence initial pupil size (4.78 mm vs 4.83 mm), latency time (520 mm vs 521 ms), and pre-PLR movement (0.328 mm2/s vs 0.325 mm2/s). CONCLUSIONS: Pupillary contraction amplitude and velocity depended on iris color, whereas pupil size and latency time were independent of iris color. Therefore, iris color might be considered when, evaluating pupillary movements in pupil perimetry.

Adult↗
PubMed1979

Continuous wave argon laser iridectomy in angle-closure glaucoma.

By using a continuous wave argon laser in a multiburn fashion, successful iridectomies were achieved in 42 out of 45 phakic eyes with either acute or chronic angle-closure glaucoma. Five of the successful procedures required multiple sittings on different days or abandonment of the primary treatment site in favor of an alternate site, or both, to attain patency. Within the immediate postoperative period, ten eyes needed retreatment to eliminate moderate pigment proliferation at the perforation site. The procedure was performed on an outpatient basis under topical anesthesia, usually required less than one-half hour for completion, and resulted in only minimal complications. Therefore, continuous wave argon laser iridectomy appears to present a viable alternative to surgical iridectomy for the definitive treatment of angle-closure glaucoma, although long-term evaluation of this modality of therapy is presently unavailable.

Adult↗
PubMed2006

Illusory color mixing upon perceptual fading and filling-in does not result in 'forbidden colors'.

A retinally stabilized object readily undergoes perceptual fading. It is commonly believed that the color of the apparently vanished object is filled in with the color of the background because the features of the filled-in area are determined by features located outside the stabilized boundary. Crane, H. D., & Piantanida, T. P. (1983) (On seeing reddish green and yellowish blue. Science, 221, 1078-1080) reported that the colors that are perceived upon full or partial perceptual fading can be 'forbidden' in the sense that they violate color opponency theory. For example, they claimed that their subjects could perceive "reddish greens" and "yellowish blues." Here we use visual stimuli composed of spatially alternating stripes of two different colors to investigate the characteristics of color mixing during perceptual filling-in, and to determine whether 'forbidden colors' really occur. Our results show that (1) the filled-in color is not solely determined by the background color, but can be the mixture of the background and the foreground color; (2) apparent color mixing can occur even when the two colors are presented to different eyes, implying that color mixing during filling-in is in part a cortical phenomenon; and (3) perceived colors are not 'forbidden colors' at all, but rather intermediate colors.

Adult↗
PubMed2005

The influence of age, duration of diabetes, cataract, and pupil size on image quality in digital photographic retinal screening.

OBJECTIVE: To evaluate the effect of age, duration of diabetes, cataract, and pupil size on the image quality in digital photographic screening. RESEARCH DESIGN AND METHODS: Randomized groups of 3,650 patients had one-field, non-mydriatic, 45 degrees digital retinal imaging photography before mydriatic two-field photography. A total of 1,549 patients were then examined by an experienced ophthalmologist. Outcome measures were ungradable image rates, age, duration of diabetes, detection of referable diabetic retinopathy, presence of early or obvious central cataract, pupil diameter, and iris color. RESULTS: The ungradable image rate for non-mydriatic photography was 19.7% (95% CI 18.4-21.0) and for mydriatic photography was 3.7% (3.1-4.3). The odds of having one eye ungradable increased by 2.6% (1.6-3.7) for each extra year since diagnosis for nonmydriatic, by 4.1% (2.7-5.7) for mydriatic photography irrespective of age, by 5.8% (5.0-6.7) for non-mydriatic, and by 8.4% (6.5-10.4) for mydriatic photography for every extra year of age, irrespective of years since diagnosis. Obvious central cataract was present in 57% of ungradable mydriatic photographs, early cataract in 21%, no cataract in 9%, and 13% had other pathologies. The pupil diameter in the ungradable eyes showed a significant trend (P < 0.001) in the three groups (obvious cataract 4.434, early cataract 3.379, and no cataract 2.750). CONCLUSIONS: The strongest predictor of ungradable image rates, both for non-mydriatic and mydriatic digital photography, is the age of the person with diabetes. The most common cause of ungradable images was obvious central cataract.

Adult↗
PubMed1998

The Alabama Age-Related Macular Degeneration Grading System for donor eyes.

PURPOSE: To develop a systematic method for identifying and grading age-related macular degeneration (ARMD) in human donor eyes, postmortem fundus appearance was compared with histopathologic assessment in eyes with a spectrum of age-related macular change. METHODS: Eyes without grossly visible, late ARMD were obtained from 8 cancer patients and 26 donors older than 50 years. Postmortem fundus appearance was graded for drusen and pigmentary change, using stereo color photographs. Eyes were processed and sectioned at 1 microm for histopathologic evaluation of macular retinal pigment epithelium-Bruch's membrane complex. The histologic diagnosis was compared with gross fundus appearance, clinical ophthalmic histories (n = 25), and clinical fundus photographs that were graded using the Wisconsin Age-related Maculopathy Grading System (n = 5). RESULTS: Ten eyes met histopathologic criteria for early ARMD. A similar proportion of eyes (27%-32%) was identified as affected by ARMD by other published histopathologic criteria. By choosing eyes with at least one druse larger than 125 microm in diameter or an area of pigment-clumping 500 microm in diameter that was visible in the postmortem fundus, ARMD cases were identified with 90% sensitivity and 95% specificity. CONCLUSIONS: The Alabama ARMD Grading System permits rational and standardized use of donor eyes in studies that are directed toward understanding the pathogenesis of ARMD.

Aged↗
PubMed1986

Lack of association between iris color and primary iris cysts.

A case-control study of 78 white patients with primary cysts of the iris was undertaken. Two control groups were established for comparison with the subjects. Contingency tables were used to evaluate the distribution of iris color among subjects and controls. Statistical testing (chi 2) indicated no significant association of iris color with the presence of a primary iris cyst (P greater than .05). These results indicated that primary iris cysts do not exhibit the association with light iris color previously documented for iris melanocytic lesions.

Adolescent↗
PubMed2000

Benzo(a)pyrene and X-rays induce reversions of the pink-eyed unstable mutation in the retinal pigment epithelium of mice.

The pink-eyed unstable (p(un)) mutation is the result of a 70kb tandem duplication within the murine p gene. Homologous deletion/recombination of the locus to wild-type occurs spontaneously in embryos and results in pigmented spots in the fur and eye that persist for life. Such deletion events are also inducible by a variety of DNA damaging agents, as we have observed previously with the fur spot assay. Here, we describe the use of the retinal pigment epithelium (RPE) of the eye to detect reversion events induced with two differently acting agents. Benzo(a)pyrene (B(a)P) induces a high frequency, and X-ray exposure a more modest increase, of p(un) reversion in both the fur and the eye. The eye-spot assay requires fewer mice for significant results than the fur spot assay. Previous work had elucidated the cell proliferation pattern in the RPE and a position effect variegation phenotype in the pattern of p(un) reversions, which we have confirmed. Acute exposure to B(a)P or X-rays resulted in an increased frequency of reversion events. The majority of the spontaneous reversions lie toward the periphery of the RPE whereas induced events are found more centrally, closer to the optic nerve head. The induced distribution corresponds to the major sites of cell proliferation in the RPE at the time of exposure, and further advocates the proposal that dividing cells are at highest risk to develop deletions.

Animals↗
PubMed1999

Dorzolamide effect on ocular blood flow.

PURPOSE: To evaluate the effect of dorzolamide on ocular blood flow in normal and glaucomatous eyes. METHODS: Twenty-six eyes with documented open-angle glaucoma of 26 patients and 13 normal control eyes of 8 age-matched subjects were included in this study. All eyes underwent color Doppler imaging for measuring peak-systolic velocity, end-diastolic velocity, and resistance index in the ophthalmic and central retinal arteries and the maximal and minimal velocities in the central retinal vein. Eyes were grouped in control and initial and advanced glaucoma categories. Measurements were made in all groups before and after application of topical dorzolamide. Intragroup comparisons between baseline and dorzolamide conditions were made using paired Student's t-test. Intergroup comparisons under baseline conditions between normal and glaucomatous eyes were made by using the one-way ANOVA test. Statistical significance was set at P < 0.05. RESULTS: The peak-systolic velocity of the central retinal artery in glaucomatous eyes and the end-diastolic velocity of the ophthalmic and central retinal arteries in all groups were significantly higher after application of dorzolamide. The minimal velocity of the central retinal vein showed significantly higher values after dorzolamide, whereas the maximal velocity remained unchanged. The peak-systolic velocity of the ophthalmic artery in all groups and the peak-systolic velocity of the central retinal artery in normal eyes also remained unchanged. The resistance index was significantly lower in the ophthalmic and central retinal arteries in all groups after dorzolamide. The intraocular pressure was significantly reduced in all groups after dorzolamide. Under baseline conditions normal control eyes and glaucomatous eyes showed differences in various measurements. Peak-systolic velocity was significantly lower in glaucomatous eyes than in normal control eyes with the exception of the ophthalmic artery in the initial glaucoma group. End-diastolic velocity was lower in glaucomatous eyes than in control eyes in both arteries. Maximal and minimal velocities of the central retinal vein were lower in glaucomatous eyes than in normal control eyes. Resistance index was higher in glaucomatous eyes than in normal control eyes in the ophthalmic artery but not in the central retinal artery. CONCLUSIONS: Most hemodynamic parameters of intraocular and periocular vessels improve after application of topical dorzolamide in both normal control and glaucomatous eyes. Dorzolamide should be regarded as a useful drug for treatment of glaucoma not only because it reduces intraocular pressure but also because it improves the ocular blood supply.

Aged↗
PubMed2001

The iris after prostanoid treatment.

Morphologic studies to date show that prostanoid-induced iris color change is not associated with any major pathologic process in the tissue. There is no evidence of melanocyte proliferation. The most likely mechanism for iris color darkening is increased melanogenesis, but this is not so marked as to cause any extensive release of melanin granules that might cause iris inflammation or even a pigmentary-type of glaucoma. Some patients, but not all, with color darkening have an apparent thickening of the anterior border zone; it remains to be established whether this is true thickening or merely if the anterior border is emphasized because of increased pigmentation.

Animals↗
PubMed1998

Color Doppler imaging of the eye and orbit.

Since the development of A- and B-scan ultrasound technique in the 1950s, significant progress in ophthalmic ultrasound has appeared. As the technology advances and ultrasound systems improve their ability to acquire and detect ultrasonic signals and to analyze them in terms of a spatial resolution and frequency distribution, there is no doubt that the extent of clinical applications will expand accordingly. Nevertheless, the fundamental physical restrictions of ultrasonography and Doppler will always remain the same. For ophthalmology, we hope that less expensive color Doppler systems with specifically designed probes, improved two-dimensional resolution, and Doppler spectrum acquisition will become more widely available. Because CDI allows for the first time a noninvasive assessment of the retrobulbar vasculature, we feel that many applications of this technology will develop for ophthalmology.

Costs and Cost Analysis↗