Evaluation of Color-Changing Effect and Complications After Nd: YAG Laser Application On Iris Surface.

BACKGROUND: The aim of this study was to evaluate the color-changing effect and adverse effects after Nd: YAG laser application on the iris surface of rabbit eyes. MATERIAL/METHODS: The study was performed on right eyes of 12 pigmented rabbits. A laser device that produces frequency doubled 532 nm wavelength Nd: YAG laser with 900 µm spot diameter was used. The laser was applied in 3 sessions at 2-week intervals, at energy levels of 0.8 mJ in Group A and 1.5 mJ in Group B. Slit-lamp examinations and measurements of intraocular pressure (IOP) using a Tono-Pen were performed before and 1 day after each laser session. Iris thickness (IT) was measured at the beginning and the end using an ultrasonic biomicroscope. The eyes were enucleated for histopathologic examination on day 60. RESULTS: On the first day after each laser session, maximum grade 1 anterior chamber flare and cells were observed in both groups. In all eyes, flare and cells disappeared at the end of the first week. There was no significant difference in the IOP and IT values between measurements performed prior to and after laser sessions during the study (p>0.05). None of the eyes showed complications such as corneal edema, hypopyon, posterior synechia, transillumination defect, or pupillary defect. In histopathological examinations, reduction in pigment density was more profound in Group B compared to Group A, which was statistically significant (p<0.019). CONCLUSIONS: There were no serious complications apart from mild transient inflammatory signs. Change in iris color was more evident at the end of the second month.

Sunlight exposure, pigmentation, and incident age-related macular degeneration.

PURPOSE: Examine potential effects of sunlight exposure, hair color, eye color, and selected gene single-nucleotide polymorphisms (SNPs) on incidence of AMD. METHODS: Subjects participated in up to five examinations over a 20-year period. Eye color, self-reported hair color as a teenager, and sunlight exposure were ascertained at the baseline examination. Presence and severity of AMD and its lesions were determined via fundus photographs. Genetic data were available on a subset of participants. The SNPs CFH Y402H rs1061170 and ARMS2 A69S rs10490924 were used to analyze genetic risk of AMD; OCA2 rs4778241 and HERC2 rs12913832 represented genetic determinants of eye color. RESULTS: Incidence of early AMD was higher in blond/red-haired persons compared with brown/black-haired persons (hazard ratio [HR] 1.25, P = 0.02) and in persons with high sun exposure in their thirties (HR 1.41, P = 0.02). However, neither was significant after adjustment for multiple comparisons. Eye (HR 1.36, P = 0.006) and hair color (HR 1.42, P = 0.003) were associated with incidence of any retinal pigmentary abnormalities (RPAs). Both remained significant after adjustment for multiple comparisons. Neither presence of alleles for light-colored eyes nor those associated with high risk of late AMD altered the association of eye or hair color with early AMD. None of the characteristics studied were significantly associated with late AMD. CONCLUSIONS: Modest associations of eye color, hair color, and HERC2 genotype with any RPAs were found. Genes for AMD did not affect these associations. Eye color phenotype was more strongly associated with outcomes than HERC2 or OCA2 genotype.

Entrance pupil size predicts retinal illumination in darkly pigmented eyes, but not lightly pigmented eyes.

PURPOSE: We determined the effect of entrance pupil size on retinal illumination. The influence of unilateral miosis on the magnitude of the pupil light reflex was studied to ascertain how a clinically significant anisocoria influences the relative afferent pupil defect (RAPD). METHODS: Miosis was induced by topical 1% pilocarpine in the right eye of 14 healthy subjects with normal eyes. The interocular difference in retinal illumination was assessed by computerized pupillometry from the stimulus response curve of the right and left eyes. The main outcome measure was the RAPD, determined by computerized pupillography, at baseline and after pilocarpine-induced anisocoria. RESULTS: Induced anisocoria produced a significant change in RAPD from baseline (mean = 1.60 dB in the miotic eye, P = 0.007). However, anisocoria correlated with RAPD only in subjects with darkly pigmented irides (Pearson correlation coefficient 0.793, P = 0.05). CONCLUSIONS: In darkly pigmented eyes, entrance pupil size significantly influenced the retinal illumination. However, retinal illumination of lightly pigmented eyes is relatively independent of entrance pupil size, presumably due to extrapupillary transmission of light through the iris and sclera. This has important implications in understanding the potential influence of anisocoria on the RAPD and also greater susceptibility of lightly pigmented eyes to light toxicity.

[A new clinical entity: ascending solar iris degeneration. Report of 284 cases]. / Une nouvelle entité clinique : la dégénérescence irienne solaire ascendante. À propos de 284 cas.

The observation in a certain number of subjects of an atypical iris depigmentation led us to study this phenomenon. Therefore, the authors engaged in a prospective study of 398 subjects (100 cases in the city of Marrakesh, and 298 in the city of Dakhla). The geography, clinical signs and environmental factors were studied. Depigmentation was observed in 55% of the population of Marrakesh and 77% of the population of Dakhla. It is bilateral, symmetric, very progressive, always begins in the inferior one-third of the iris, and always spares the superior iris covered by the eyelid. By the time the depigmentation reaches the middle one-third, the inferior one-third also begins to demonstrate stromal atrophy: (26 cases). Of the 45 subjects with normal iris pigmentation, 31 cases spend more than 8 hours per day in the shade, and 26 cases constantly use some means of solar protection (sunglasses, caps, "Taraza", "Feroual"). Thus, this acquired iris depigmentation of an ascending nature, accompanied by an advanced stage involving primarily inferior iris atrophy, appears to be closely associated with exposure to the sun. Ascending solar iris degeneration, if we may refer to it as such, is a clinical entity never before reported in the literature. Now that we are faced with this new condition, numerous questions arise, to which future research must respond. Are there other factors in addition to sun exposure, which may lead to the depigmentation? Does this condition lead to further ocular pathology (due to the depigmentation and stromal atrophy)? Must solar protection be prescribed systematically for anyone at risk?

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.

[The dependence of the parasympathetic reaction of the mesencephalic section of the brain stem to age-, sex- and pigment-reagent-related factors]. / Zavisimost' parasimpaticheskoi reaktsii mezentsefal'nogo otdela stvola ot vozrastnogo, polovogo i pigment-reagentnogo faktorov.

Photoelectron pupillograph measurements of pupillary responses to light were made in 198 healthy individuals. Photoreaction of the pupils was declining with age contrary to the reciprocity rate which was stable (3.01-3.56). It indicates on the relative stability of parasympathetic-sympathetic relations. Young males with hyperpigmented irises had hyperactive parasympathetic reaction which sharply decreased to normal values at the age of 26-30 years. Estimated standard values of time, strength and speed of pupillomotor reaction can be used for comparative evaluation of autonomic neuromotor and brain structures involvement in various neurological diseases. These values may serve as initial point for devising medical algorithms and computer programs.

Visual pigment bleaching in isolated salamander retinal cones. Microspectrophotometry and light adaptation.

Visual pigment bleaching desensitizes rod photoreceptors greatly in excess of that due to loss of quantum catch. Whether this phenomenon also occurs in cone photoreceptors was investigated for isolated salamander red-sensitive cones. In parallel experiments, (a) visual pigment depletion by steps of bleaching light was measured by microspectrophotometry, and (b) flash sensitivity was measured by recording light-sensitive membrane current. In isolated cones, visual pigment bleaching permanently reduced flash sensitivity significantly below that due to the reduction in quantum catch, and there was little spontaneous recovery of visual pigment. The "extra" desensitization due to bleaching was most prominent up to bleaches of approximately 80% visual pigment and reached a level approximately 1 log unit beyond that due to loss of quantum catch. At higher bleaches, the effect of loss of quantum catch became more important. Bleaching did not greatly reduce the maximum light-suppressible membrane current. A 99% reduction of the visual pigment permanently reduced the circulating current by only 30%. Visual pigment bleaching speeded up the kinetics of dim flash responses. All electrical effects of bleaching were reversed on exposure to 11-cis retinal, which probably caused visual pigment regeneration. Light adaptation in photopic vision is known to involve significant visual pigment depletion. The present results indicate that cones operate with a maintained circulating current even after a large pigment depletion. It is shown how Weber/Fechner behavior may still be observed in photopic vision when the contributions of bleaching to adaptation are included.

Photodynamic retinal vascular thrombosis. Rate and duration of vascular occlusion.

Dye-sensitized photochemical thrombosis is a new method of producing vascular occlusion in the eye for experimental purposes. The rate and duration of photodynamic occlusions of branch retinal vessels was measured in pigmented and albino rat eyes after intravenous injection of the photosensitizing dye, rose bengal. Selected vessels were exposed to focused, white light until vascular occlusion was observed biomicroscopically. A slit lamp was used for a light source in this procedure, allowing adjustment of spot size, shape, and orientation. Arterioles occluded more rapidly than venules, and the time required to produce vascular occlusion decreased when animals breathed pure oxygen administered by face mask. Rose bengal doses of 40 and 80 mg/kg were effective, 20 mg/kg was partially effective, and 1 and 10 mg/kg were ineffective in producing branch arteriole occlusion at a light intensity of 73.5 mW/cm2. The total light energy required to produce occlusion increased from an average of 0.06 J using 80 mg/kg to 0.50 J using 20 mg/kg of rose bengal. Lower light intensities produced vessel occlusion less rapidly (46 mW/cm2) or not at all (17.5 mW/cm2). The rate of retinal arteriolar occlusion was not affected by ocular pigmentation. The duration of branch vessel occlusion depended on length of vessel treated and did not exceed 3 days in arterioles and 4 days in venules. Histologic sections showed discrete areas of retinal and choroidal vascular thrombosis confined to the area of direct light exposure. Choroidal vascular thrombosis and outer retinal damage predominated in eyes treated at low light intensity. Thrombosis usually extended into the deep choroidal vessels in albino but not pigmented eyes.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of a mutationally unstable X-chromosome in Drosophila melanogaster for mutagenicity testing.

Somatic eye-colour mutations in an unstable genetic system, caused by a transposable element in the white locus of the X-chromosome in Drosophila melanogaster, is suggested as an assay system for mutagenicity testing. The system is evaluated by comparison with a corresponding system in a stable X-chromosome. Its sensitivity is confirmed with X-ray and EMS treatment, and it is found to be confined to the specific segment of the X-chromosome where the transposable element is localized.

Location of an eye mutant in the onion fly Hylemya antiqua Meigen using a pericentric chromosome inversion.

With the use of a pericentric inversion in chromosome 3, an eye color mutant in the onion fly was located in chromosome 3. No recombination occurs in males; 40.2% recombination was observed in females. This linkage through the male facilitates further cytogenetic research on structural aberrations involving chromosome 3.