Dark Irides Research Articles

Retinal ischemia and angle neovascularization in proliferative diabetic retinopathy

PURPOSE: To analyze the relationship between the extent of retinal ischemia in proliferative diabetic retinopathy and angle neovascularization. METHODS: Panoramic fundus fluorescein angiography and 360-degree fluorescein gonioangiography to detect the angle neovascularization were performed on 70 eyes of 46 patients with proliferative diabetic retinopathy. Statistical significance was evaluated by chi-squared test. Statistical significance was evaluated if the value (T) was greater than the level of significance, χ 0.05 2(2) = 5.99. RESULTS: Retinal ischemia in fluorescein angiography was evaluated in four areas: capillary occlusion in (1) temporal raphe; (2) radial peripapillary capillaries; (3) the midperiphery (grade I, less than 25% of the area; grade II, 25% to 50%; grade III, 50% to 75%; grade IV, more than 75%); and (4) optic disk with neovascularization. The angle neovascularization was divided into two types: type I (14 eyes) and type II (12 eyes). Capillary occlusion in the temporal raphe and radial peripapillary capillaries, and papillary leakage significantly increased the risk of angle neovascularization (T = 8.28, 10.04, 6.44 respectively). Grade III and IV capillary occlusion in the midperiphery had a significant risk of angle neovascularization when compared with grade I (between grade III: T = 9.03, grade IV: T = 19.36) and II (between grade III: T = 6.31, grade IV: T = 16.09). CONCLUSION: Risk factors for angle neovascularization were retinal nonperfusion in the midperiphery wider than grade III, capillary occlusion in the radial peripapillary capillaries and temporal raphe, and optic disk. Fluorescein gonio angiography was found to be a powerful tool for the early detection of angle neovascularization, especially in dark irides.

Prior Topical Anesthesia Reduces Time to Full Cycloplegia in Chinese

Purpose: To investigate the effect of prior anesthesia on the time to full cycloplegia in young Chinese subjects. Methods: The amplitude of accommodation was monitored over a 50-minute interval after the application of 1% cyclopentolate hydrochloride with a pretreatment of 0.4% benoxinate (oxybuprocaine) or 0.9% saline solution (control). Using a nonlinear mathematical model, the rate of accommodative loss (k) and the time required for 95% of total cycloplegia (T 95%) were determined. Results: Statistical analysis revealed a significantly faster rate of accommodative loss ( P < .0001) after prior anesthesia (0.129 ± 0.05) compared with the controls (0.103 ± 0.04). T 95% was noted at 26.43 ± 10.22 minutes after prior anesthesia, which was significantly shorter ( P < .0001) than that after the saline treatment (35.28 ± 16.51 minutes). Conclusions: Prior application of topical anesthetic can shorten the time to full cycloplegia for people, such as the Chinese, with dark irides.

Diode Laser Contact Transscleral Cyclophotocoagulation for Refractory Glaucoma in Asian Patients

To evaluate the effectiveness and safety of diode laser contact transscleral cyclophotocoagulation in Asian patients with refractory glaucoma by lower energy settings with an innovative probe featuring a glass ball tip that focused the laser beam onto the ciliary body. This prospective clinical study included consecutive Asian patients with dark irides and confirmed for glaucoma. Only one eye of each patient was treated. Diode laser contact transscleral cyclophotocoagulation treatment was performed with the center of the probe placed 1.5 mm behind the limbus. About 30 pulses of 810-mm laser radiation (power, 1.8 to 2.0 W; duration, 0.3 to 0.5 second) were applied around the eye. Patients were examined at fixed postoperative intervals. Intraocular pressure levels and postoperative complications were recorded. The relation between patient and disease characteristics, total laser energy delivered, and intraocular pressure effects were analyzed. Thirty-three patients were studied, with a mean follow-up period of 9.4 months. An average 56% of patients showed a 30% or greater drop in intraocular pressure. About 38% of patients achieved sustained intraocular pressure lowering to below 22 mm Hg at 18 months. Complications were few and included transient hypotony and iritis. In Asian patients with refractory glaucoma or painful glaucomatous eyes with poor visual acuity (defined for this study as worse than 20/200), low-energy-setting diode laser contact transscleral cyclophotocoagulation by means of the glass ball probe is relatively effective and safe.

Efficacy of a mydriatic spray in the pediatric population.

Children often resist instillation of mydriatic drops for dilated fundus evaluation. As cycloplegic sprays have proven useful, this study's aim was to demonstrate efficacy of a mydriatic spray. Twenty-two healthy subjects, ages 2 to 8 years, participated in the study. All but two had dark brown irides. Subjects were given either one drop each of 1% tropicamide and 2.5% phenylephrine in each eye or one application of mydriatic spray (containing concentrations of 0.5% tropicamide and 2.5% phenylephrine) to each closed eyelid. Pupils were measured with a pupil gauge before drug delivery and every 10 min thereafter, for 40 min. Repeated measures analysis of variance for the five time intervals demonstrated no significant difference between the two application methods nor in the method/time interaction, but a statistically significant increase in pupil size over time (p < 0.0005) for each method. A t-test revealed no statistically significant difference in pupil size (p > 0.05) between the two methods of drug administration at 40 min after application. This study suggests that use of mydriatic sprays on closed eyelids is as efficacious as use of mydriatic drops in open eyes for children.

Comparison of Argon Laser Iridotomy and Sequential Argon Laser and Nd:YAG Laser Iridotomy in Dark Irides

A prospective study was performed to compare argon laser iridotomy and sequential argon laser and Nd:YAG laser iridotomy in dark irides. Twenty-four eyes of 17 patients underwent laser iridotomies; 13 underwent argon laser iridotomies and 11 underwent sequential argon laser and Nd:YAG laser iridotomies. The argon laser settings were standardized at 1.2 W, 50-mum spot size, and 0.1-second duration. The Nd:YAG laser was set at 2.5 mJ and single-pulse shots were used. All of the iridotomies were patent at the end of one treatment session. The mean total energy used for argon laser iridotomy was 8.28 J. For sequential iridotomy, 3.12 J was used for the argon laser stage and 7.5 mJ for the Nd:YAG laser stage. The total argon laser energy used can be reduced by 2.65 times by using the sequential laser iridotomy technique.

1% Cyclopentolate Hydrochloride: Another Look at the Time Course of Cycloplegia Using an Objective Measure of the Accommodative Response

The time course of cycloplegia was measured by monitoring residual accommodation after the application of 1 drop (29.3 microliters) of 1% cyclopentolate hydrochloride. Three different measures of residual accommodation were made, one objective assessment with an optometer, and two subjective assessments similar to those used by previous investigators. Pupil diameter was also measured in a subgroup of individuals to compare the time course of the induced mydriasis to that of the cycloplegia. When residual accommodation is measured objectively, maximum cycloplegia occurs 10 min after the application of 1% cyclopentolate hydrochloride in individuals with light irides. This result suggests that the standard clinical protocol of delaying refraction 30 to 60 min after the application of cyclopentolate hydrochloride may be too conservative for individuals with light irides. For individuals with dark irides, 30 to 40 min is required for maximum cycloplegia, and the magnitude of residual accommodation in these individuals is similar to that found in light iris individuals at 10 min. When subjective measures are used to estimate residual accommodation, more accommodation is present and the time at which maximum cycloplegia occurs is delayed for individuals with light irides. These results are in agreement with previous studies using subjective techniques. Regardless of iris color or measurement method, the time course for pupil dilation is not the same as the time course for cycloplegia.

Sequential argon-YAG laser iridotomies in dark irides.

Laser iridotomies in dark coloured irides are associated with higher complication and failure rates. A prospective clinical study to evaluate the use of the argon and Nd:YAG laser in sequential combination for iridotomy was carried out on 20 eyes of 13 patients with dark irides. Patent iridotomies were achieved in single treatment sessions for all the eyes. Iridotomy closure was observed in one eye during a mean follow-up period of 14 months (range 6-20 months). Complications from the treatment occurred in five eyes and were minor. Total mean energy used for the argon and Nd:YAG stages respectively were a third of most studies on pure argon and Nd:YAG iridotomies. Sequential argon-YAG laser iridotomy combines most of the advantages of both laser types while avoiding some of their disadvantages. We find it a safe and effective tool for iridotomy in otherwise difficult dark irides.

The Influence of Iris Pigmentation on the Miotic Effect of Thymoxamine

We performed a randomly assigned, double-masked, placebo-controlled study in 78 patients with varied iris pigmentation to evaluate the influence of iris pigmentation on the ability of 0.1% thymoxamine to reverse mydriasis produced by 2.5% phenylephrine. Patients were chosen so that a 1.6:1 ratio of dark to light irides was obtained. Within one-half hour after medication, thymoxamine-treated nonbrown irides constricted significantly compared to their fellow placebo-treated irides (P less than .001). Thymoxamine-treated pupils of nonbrown irides were 1.0 to 3.1 mm smaller than placebo-treated fellow eyes. Thymoxamine-treated light brown irides constricted less (0.6 to 2.0 mm) and more slowly compared to fellow placebo-treated irides. Thymoxamine did not reverse the mydriasis in eyes of patients with dark brown irides. Thymoxamine appears similar to other adrenergic agents that bind to melanin, delaying onset and strength of action. Its efficacy as presently formulated may be limited, in part, by iris color.

Time Course of Thymoxamine Reversal of Phenylephrine-Induced Mydriasis

We conducted a randomized, double-masked, paired comparison of 0.1% thymoxamine vs placebo for the reversal of phenylephrine-induced mydriasis. Mydriasis was induced with 2.5% phenylephrine in each eye of 74 subjects (148 eyes). Each subject then received 0.1% thymoxamine in one eye and placebo in the other eye. Pupillary measurements were obtained at regular intervals during the ensuing 8 hours. At all intervals, a greater percentage of thymoxamine-treated eyes returned to baseline pupillary diameters compared with placebo-treated eyes (P less than or equal to .01). For subjects in whom both pupils returned to baseline, thymoxamine-treated eyes returned to baseline in a mean of 2.2 hours, vs 5.2 hours for placebo (P less than .0001). Among thymoxamine-treated eyes, those with light irides responded more rapidly than those with dark irides, returning to baseline in 1.6 vs 2.8 hours, respectively (P = .0046). After constriction to baseline pupillary diameter had been achieved, no patients experienced a rebound dilation.

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.

Technique for testing the patency of laser iridotomies.

With laser iridotomy it may often be difficult to achieve total penetration of the iris, particularly in very light or very dark irides. It may be impossible to determine with the slit-lamp whether a small laser iridotomy is functionally penetrating. We describe a straightforward method to test iridotomies for aqueous flow patency. Transcorneally introduced fluorescein is used to delineate any aqueous bulk flow from the posterior to the anterior chamber.

Relationship of Senile Macular Degeneration to Ocular Pigmentation

We prospectively evaluated 650 consecutive white patients with senile macular degeneration and compared them to a control group of 363 patients. Ocular pigmentation (iris color and fundus pigmentation) was recorded for each patient, as was hair color (as a child and young adult) and age at evaluation. Patients were from the New England states and Florida. Our most significant finding was that 494 patients with senile macular degeneration (76%) had light-colored irides compared with 145 of the controls (40%). Fundus pigmentation closely corresponded to iris pigmentation (P less than 0.01). Hair color was blond or light brown in 370 of the patients with senile macular degeneration (57%) and in 105 of the controls (29%). Further, there was a tendency for individuals with lightly pigmented irides to have senile macular degeneration at an earlier age than those with dark irides (P less than .01). Thus, increased ocular pigmentation tends to decrease the risk of developing senile macular degeneration.

An ethnic comparison of anterior segment characteristics: A preliminary report

Introduction With the introduction of more sophisticated keratometers it has been possible to construct model corneas upon which off the peg type contact lenses may be designed. These are typically aspherical, gas permeable and perhaps ultimately disposable, but essentially contoured to the average cornea. Traditionally however one prescribed individually designed, PMMA lenses which may be retrospectively modified as required and indeed clinical experience frequently suggests variations from the norm can and do occur. Further we practice in a multi-racial society in an era of international travel which must prompt one to question if a lens design on say a caucasian model cornea is equally compatible to a cornea of another patient from a different racial group? The purpose of this paper is to overview some differences in the corneal topography of various ethnic groups in addition to presenting preliminary results of a larger on-going study. Racial Classifications Racial classification is complex, enigmatic and often contradictory. Differences between people come from many sources but are broadly divided into those that are hereditary or genetic and those due to environment. Furthermore, these two factors interact with each other in that the manifestation of the genetic factor depends on the environment. Both J. Z. Young (1971) and C. S. Coon (1965) write of three major poles of differences among the world's people: 1) The Negroids are the principal inhabitants of Africa and generally are dark skinned and spiral haired. Facial features show common everted lips, a broad nose and dark irides. 2) The Caucasoids are the major inhabitants of Europe and Northern America. In general they have the fairest skin and the greatest frequencies of blond hair and light eyes and are characterised by a thin nose and lips. 3) The Mongoloids mainly live in Asia. The principal morphological traits of the mongoloids include coarse, straight black hair, little beard and body hair, yellowish skin, flattish faces with prominent cheek bones. Their noses are either low bridged or aquiline. Their eyes are generally brown with slanted eyelids. Epicanthic eyefold is of higher percentage than the other racial populations. A fourth, smaller population grouping of genes may be called Australoid, characteristic not only of Australian aboriginies but of other people in parts of the East Indies. Their genetic build up shows a dark skin but other characteristics of body form and of hair resemble those produced by Caucasian genes. Structural or morphological variations may of course be considered in terms of regional groupings of genes coupled with presumed environmental interaction. In fact, the distinction of genes usually changes gradually with distance. Therefore, in other words, t he components of men's biological variability change gradually with geographical distance, as for instance, the situation of skin colours, head shape and blood groups. This graduation in distribution makes it impossible to divide men into sharp distinct races and in describing sub-races one may have to rely on a common cetttral tendency from which exceptions can and do occur (Coon, 1965).

Disposition of cyclophosphamide in the rabbit and human cornea

Rabbit (dark irides and albino) and human corneas were excised and mounted in a Lucite chamber in order to determine the permeability of cyclophosphamide-14C and to identify its metabolites. The chromatographic scans obtained from the developed thin-layer plates showed only one peak for either rabbit or human corneas which corresponded to cyclophosphamide. By measuring the permeability of cyclophosphamide across the intact cornea, stroma alone, epithelium/stroma, and stroma/endothelium, it was possible to determine the resistance to penetration for each layer. The epithelium was the rate determining barrier, whereas both the stroma and endothelium offered little resistance. The stroma behaves as an inert sieve with drug diffusing through an aqueous media of gel-like mucopolysaccharide interspersed by a matrix of collagen fibrils.

Mydriatic Effect of Anticholinergic Drugs Used during Reversal of Nondepolarizing Muscle Relaxants

Large doses of anticholinergic drugs (atropine, glycopyrrolate) produced mydriasis in a group of adults with no eye abnormalities except strabismus, though the usual intramuscular and intravenous doses of these drugs do not have this tendency. Such large doses are often given intravenously during general anesthesia to prevent the side effects of neostigmine methylsulfate, which is used to reverse the effect of nondepolarizing muscle relaxants. Neostigmine methylsulfate (Prostigmin) reduced the mydriatic effect when given intravenously in conjunction with atropine or glycopyrrolate. Mydriasis was more likely to occur in lightly pigmented eyes than in eyes with dark irides. Pilocarpine eyedrops instilled at the beginning of anesthesia caused miosis that persisted after the large intravenous doses of atropine or glycopyrrolate were given. To prevent an attack of acute angle-closure glaucoma in any patient who is to receive large doses of anticholinergic drugs during general anesthesia, miotic drug therapy should be continued before, during, and after anesthesia at the same frequency as when awake.

The problem of cycloplegia in the pediatric age group: a combination formula for refraction.

Cycloplegic refraction and indirect ophthalmoscopy are essential to evaluation of the pediatric patient. Unfortunately, along with this practice occur the attendant risks of toxicity and the unpleasantness of instillation. The literature that documents the development of cycloplegic agents is often contradictory regarding efficacy and side effects. It is presented for perspective. We have found that efficacy and discomfort are inseparable; however, as with efficacy and toxicity they are directly related to the concentration used. The case is therefore made to use each agent in its minimal effective concentration and thereby minimize both discomfort and toxicity. Our combination of 1.3% cyclogyl, .167% mydriacil, and 1.6% phenylephrine accomplishes effective cycloplegia for refraction and indirect ophthalmoscopy, has a rapid onset and short duration, works reliably in dark irides, is accomplished in a single encounter with the patient, and exhibits none of the side effects of the individual agents in our series.

Mydriatic Effect of Anticholinergic Drugs Used During Reversal of Nondepolarizing Muscle Relaxants

Large doses of anticholinergic drugs (atropine, glycopyrrolate) produced mydriasis in a group of adults with no eye abnormalities except strabismus, though the usual intramuscular and intravenous doses of these drugs do not have this tendency. Such large doses are often given intravenously during general anesthesia to prevent the side effects of neostigmine methylsulfate, which is used to reverse the effect of nondepolarizing muscle relaxants. Neostigmine methylsulfate (Prostigmin) reduced the mydriatic effect when given intravenously in conjunction with atropine or glycopyrrolate. Mydriasis was more likely to occur in lightly pigmented eyes than in eyes with dark irides. Pilocarpine eyedrops instilled at the beginning of anesthesia caused miosis that persisted after the large intravenous doses of atropine or glycopyrrolate were given. To prevent an attack of acute angle-closure glaucoma in any patient who is to receive large doses of anticholinergic drugs during general anesthesia, miotic drug therapy should be continued before, during, and after anesthesia at the same frequency as when awake.

Effects of iris pigmentation on response of ocular pressure to timolol

Timolol ophthalmic solution effectively reduced mean intraocular pressure (IOP) in Negro and Caucasian patients with chronic open angle glaucoma and untreated IOP of 22 mm Hg or higher. No differences in pressure lowering response were observed among the races although the Negroes required somewhat higher timolol concentrations to produce similar reductions from baseline IOP. Negro patients also appeared to have a more severe disease as indicated by the number of prior antiglaucoma drugs required and the untreated (baseline) pressures. An unexpected finding was the significantly greater number of Caucasians with dark irides who were discontinued from therapy because of inadequate pressure reduction.

The Mechanism of Timolol in Lowering Intraocular Pressure

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.

A possible enzymatic basis for the differential action of mydriatics on light and dark irides.

The Journal of PhysiologyVolume 119, Issue 1 p. 102-117 ArticleFree Access A possible enzymatic basis for the differential action of mydriatics on light and dark irides Winifred J. Angenent, Winifred J. AngenentSearch for more papers by this authorG. B. Koelle, G. B. KoelleSearch for more papers by this author Winifred J. Angenent, Winifred J. AngenentSearch for more papers by this authorG. B. Koelle, G. B. KoelleSearch for more papers by this author First published: 28 January 1953 https://doi.org/10.1113/jphysiol.1953.sp004831Citations: 17AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume119, Issue1January 28, 1953Pages 102-117 RelatedInformation