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At least 811 records · Page 45Linked to original sources
PubMed2001

Induction of tyrosinase gene transcription in human iris organ cultures exposed to latanoprost.

OBJECTIVE: Topical administration of latanoprost sometimes induces gradual iris darkening. The present study was undertaken to determine if latanoprost can increase transcription of the gene for tyrosinase, an important enzyme in the biosynthesis of melanin. Results from brown, hazel, and blue irides were compared. METHODS: Iris tissue was isolated from 30 pairs of postmortem human donor eyes, and 2 iris segments from each eye were incubated in tissue culture medium supplemented with 200nM latanoprost acid or vehicle for 7 days. Tyrosinase messenger RNA (mRNA) was determined using real-time polymerase chain reaction analysis (TaqMan quantitative polymerase chain reaction). Results for tyrosinase mRNA were normalized according to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA in each sample. RESULTS: Tyrosinase mRNA expression was similar in blue and hazel irides, and ranged from 0.7-fold to 12.6-fold greater than GAPDH expression. In contrast, control brown iris culture tyrosinase expression ranged from 6.4-fold to 265-fold greater than GAPDH expression. Induction of tyrosinase mRNA by latanoprost was below threshold in all the blue iris cultures (n = 8 pairs), present in 1 of 9 hazel iris cultures, and present in 5 of 13 brown iris cultures. Mean induction in the responding hazel iris cultures was 1.40-fold. Mean induction among the responding brown iris cultures was 2.97-fold. CONCLUSIONS: These observations support the view that iris darkening associated with latanoprost treatment reflects induction of tyrosinase expression. Moreover, they suggest that the probability that latanoprost will increase tyrosinase expression is directly related to the magnitude of tyrosinase expression before treatments are initiated. CLINICAL RELEVANCE: The variability of iris darkening with latanoprost may reflect natural variation in the basal transcription of tyrosinase.

Adult↗
PubMed1976

Pigmented iris angiography.

A small volume of concentrated fluorescein was used in a technique of fluorescein angiography in rabbits. The procedure is not accompanied by the usual risks of general anesthesia in rabbits. Angiographic findings demonstrated that the pigmented rabbit iris vessel pattern is similar to that found in albino rabbits.

Albinism↗
PubMed1978

The mechanism of timolol in lowering intraocular pressure. In the normal eye.

A single-drop, double-masked, randomized, placebo-controlled study of the mechanism of the ocular-pressure lowering property of timolol maleate, a beta-adrenergic blocker, was carried out in 23 normal subjects, using fluorophotometry. Timolol suppressed aqueous formation in all subjects. The range of suppression was 13% to 48%, with a mean +/- SD of 34% +/- 9%. The drug had no effect on anterior chamber volume or endothelial permeability to fluorescein and, apparently, had no effect on outflow resistance. No differences were observed between its effect on men and women or between eyes with light and dark irides.

Adult↗
PubMed1980

Congenital Horner's syndrome.

Patients with congenital Horner's syndrome (who seemed, on the basis of their clinical history and the distribution fo anhidrosis, to have a preganglionic lesion) had partial mydriatic failure with hydroxyamphetamine hydrobromide and a supersensitivity to phenylephrine hydrochloride. This apparent paradox can be readily explained by postulating an aorthograde transsynaptic dysgenesis of the postganglionic neuron, such as has been demonstrated in the sympathetic nervous system of newborn animals. The failure of hydroxyamphetamine to cause mydriasis indicates damage to the postganglionic sympathetic neuron, but in the neonate this damage may be secondary to a preganglionic lesion.

Child↗
PubMed1983

Fluorescein angiography of the heavily pigmented iris and new dyes for iris angiography.

An inexpensive adapter mounted in front of the objective lens of a fundus camera permits routine fluorescein angiography of the heavily pigmented iris. Angiograms of these patients whose iris pigment was dense enough that standard methods of iris angiography would disclose little or no information were performed with the use of the adapter. For use in the study of the iris vasculature in the research laboratory, three dyes with spectral characteristics different from those of fluorescein allow angiography of the iris at different wavelengths. Angiograms using these dyes were performed on the eye of a cynomolgus monkey. The angiograms were each taken as close as possible to the same time sequence and show dramatically different filling and staining patterns.

Animals↗
PubMed1988

Fuchs' heterochromic iridocyclitis in blacks.

Fuchs' heterochromic iridocyclitis (FHI) is a frequently overlooked cause of anterior uveitis. Improper diagnosis may lead to unnecessary therapy. Dark brown irides may demonstrate heterochromia poorly. We believe that FHI may be overlooked in blacks because of a frequent lack of obvious heterochromia and the frequent presence of iris nodules. Heterochromia is not necessary for the diagnosis of FHI if other clinical features of the syndrome are present. In our series of 54 whites and 13 blacks with FHI, heterochromia occurred in 50 (92%) whites and ten (76%) blacks (nonsignificant difference). Iris nodules occurred in 11 (20%) whites and four (30%) blacks (not significant). Statistically significant differences occurred with cataract/aphakia in 41 (75%) whites and three (23%) blacks and with glaucoma in six (11%) whites and five (38%) blacks.

Age Factors↗
PubMed1989

Ultraviolet light exposure and risk of posterior subcapsular cataracts.

Posterior subcapsular (PSC) cataracts are a visually disabling form of cataract and account for 40% of surgical cases. Although PSC opacities may occur following intraocular inflammation, trauma, or use of steroids, the cause is often unknown. A case-control study was undertaken to investigate the role of exposure to ultraviolet light in the B range (UV-B) and other potential risk factors for the development of PSC cataracts. Surgical PSC cataract cases from a large rural ophthalmic practice on the lower eastern shore of Maryland were matched with phakic controls without PSC cataract changes from the same geographic area by age, sex, and referral pattern. All patients with PSC opacities who underwent cataract surgery in a 12-month period were chosen. One hundred sixty-eight cases and 168 controls were interviewed regarding sunlight exposure, drug use, occupational history, history of diabetes, hypertension, and other diseases. Matched-pairs analyses indicated that a history of relatively high exposure to UV-B was associated with increased risk of PSC cataracts. The association of PSC cataracts with steroid use and diabetes was reconfirmed. Subjects with blue eyes and less than high school education were also at increased risk for PSC cataracts. Smoking and hypertension were not found to be PSC cataract risk factors. These data suggest that UV-B exposure may be an important risk factor for PSC cataracts.

Adult↗
PubMed1989

Exposure to sunlight and other risk factors for age-related macular degeneration.

As some ultraviolet (UV) radiation is transmitted by the ocular media, there is a growing concern that there may be a possible relationship between long-term exposure to ultraviolet radiation and increased risk of age-related macular degeneration. To address this question, a survey was conducted of 838 Maryland watermen who had well-characterized ocular UV-A and UV-B exposure. Fundus photographs were taken and graded for presence of exudative disease, geographic atrophy, focal hyperpigmentation of the retinal pigment epithelium, and drusen that were large and/or confluent. None of the subjects in these analyses were aphakic. The results suggested that age-related macular degeneration was not associated with cumulative exposure to either UV-A or UV-B. Age and the presence of nuclear opacity were independently associated with an increased risk of macular degeneration. Thus, we found that in phakic subjects, even with high levels of sunlight exposure, there was no evidence of increased risk of age-related macular degeneration associated with UV-B or UV-A exposure.

Adult↗
PubMed1989

MK-927: a topically effective carbonic anhydrase inhibitor in patients.

The effects on intraocular pressure of the novel topical carbonic anhydrase inhibitor MK-927 were investigated for the first time in patients. Three drops of 2% MK-927 was administered in a two-center, double-masked, randomized, placebo-controlled, two-period crossover study in 25 patients with bilateral primary open angle glaucoma or ocular hypertension. At 4.5 hours after the dose, MK-927-treated eyes demonstrated a peak mean change of -7.7 mm Hg from a mean intraocular pressure of 27.8 mm Hg immediately before the dose; this compares with a change of -3.9 mm Hg from a mean intraocular pressure of 28.2 mm Hg when the same eyes were treated with placebo. The peak mean percent change in intraocular pressure in eyes treated with MK-927 was -26.7% at 6 hours after the dose compared with a change of -13.7% after treatment with placebo. No contralateral effect on intraocular pressure due to MK-927 was observed.

Adult↗
PubMed1992

Visual symptoms associated with choroidal neovascularization. Photopsias and the Charles Bonnet syndrome.

One hundred consecutive patients with macular choroidal neovascularization were studied in a cross-sectional fashion. Evidence of bilateral choroidal neovascularization was present in 31 patients. Among the 100 subjects, 59% related a history of seeing flickering or flashing lights (photopsias) in the affected eye or eyes. The colors varied, but in 59% of instances the lights were white. Twelve subjects experienced formed hallucinations (Charles Bonnet syndrome); in nine (75%) of these patients, the sequelae of choroidal neovascularization were bilateral. Symptoms that are commonly attributed to vitreoretinal tractional phenomena as well as neurologic and/or psychiatric disease are also frequently encountered in patients with macular degeneration associated with choroidal neovascularization.

Adult↗