Iris color and visual functions.

BACKGROUND: The aim of this study was to evaluate if iris color is associated with differences in visual functions such as intraocular straylight (IOSL), contrast sensitivity (CS), or best-corrected visual acuity (BCVA). METHODS: In this retrospective cohort study, which is a subgroup analysis of a large prospective trial about visual impairments in European car drivers, we included 853 persons between 20 and 80 years of age and without a history of ocular surgery or any eye disease including cataract. Subjects participated in an ophthalmological examination, grading of lens opacity, and the measurement of visual functions such as IOSL, CS, and BCVA. Dependent on iris color, participants were divided into four groups: light-blue, blue-grey, green-hazel, and brown. RESULTS: Independent of age, IOSL was significantly (all p values < 0.0001, Fisher's LSD test) higher in participants with light-blue colored iris (1.14 log(IOSL) [95 % CI: 1.11-1.17]) compared to participants with blue-grey (1.07 log(IOSL) [95 % CI: 1.05-1.09]), green-hazel (1.06 log(IOSL) [95 % CI: 1.04-1.08]) or brown (1.06 log(IOSL) [95 % CI: 1.04-1.08]) iris color. CS was also lower in participants with light-blue pigmented irises (1.60 log(CS) [95 % CI: 1.58-1.62]) than in the other groups, but statistically significant (p = 0.013, Fisher's LSD test) only compared to brown iris color. For BCVA we could not found any difference between the four groups. CONCLUSIONS: We could show in this study that iris color has a significant impact on IOSL and to a lower degree on CS, but not on BCVA. Persons with light-blue iris color who showed significantly higher IOSL values therefore may experience disability glare in daily situations such as driving at night more often than others.

Profiles of intraocular pressure in human donor eyes during femtosecond laser procedures--a comparative study.

PURPOSE: To compare four different femtosecond laser devices (IntraLase FS, Zeiss VisuMAX, and Ziemer Femto LDV, and a prototype Schwind SmartTech Nanolaser) in human donor eyes with regard to their effects on IOP during femtosecond laser flap cutting. In order to get cuts parallel to the corneal surface, the cornea has to be forced into a defined shape and current femtosecond laser devices either use a flat or a curved patient interface design to achieve applanation. METHODS: IOP was measured in enucleated eyeballs (n = 46) not suitable for keratoplasty by direct cannulation of the vitreous body. A second cannula was inserted to adjust IOP to a baseline pressure of 20 mm Hg. The eyeballs were lifted by custom made supporting stands to achieve an appropriate height and put under the femto-LASIK devices. RESULTS: The flat patient interfaces gave rise to higher IOPs (IOP max = 328.3 ± 29.8, 228.8 ± 28.4, and 201.09 ± 21.4 mm Hg), whereas the curved patient interface caused lower IOPs in response to attachment and suction (IOP max = 104.9 ± 13.4 mm Hg). CONCLUSIONS: Based on previous findings of visual field defects after LASIK, and as a consequence of the present study, it seems feasible to design patient interfaces in a more physiologic manner to prevent high IOPs during refractive procedures.

Mitochondrial haplogroups and control region polymorphisms in age-related macular degeneration: a case-control study.

BACKGROUND: Onset and development of the multifactorial disease age-related macular degeneration (AMD) are highly interrelated with mitochondrial functions such as energy production and free radical turnover. Mitochondrial dysfunction and overproduction of reactive oxygen species may contribute to destruction of the retinal pigment epithelium, retinal atrophy and choroidal neovascularization, leading to AMD. Consequently, polymorphisms of the mitochondrial genome (mtDNA) are postulated to be susceptibility factors for this disease. Previous studies from Australia and the United States detected associations of mitochondrial haplogroups with AMD. The aim of the present study was to test these associations in Middle European Caucasians. METHODOLOGY/PRINCIPAL FINDINGS: Mitochondrial haplogroups (combinations of mtDNA polymorphisms) and mitochondrial CR polymorphisms were analyzed in 200 patients with wet AMD (choroidal neovascularization, CNV), in 66 patients with dry AMD, and in 385 controls from Austria by means of multiplex primer extension analysis and sequencing, respectively. In patients with CNV, haplogroup H was found to be significantly less frequent compared to controls, and haplogroup J showed a trend toward a higher frequency compared to controls. Five CR polymorphisms were found to differ significantly in the two study populations compared to controls, and all, except one (T152C), are linked to those haplogroups. CONCLUSIONS/SIGNIFICANCE: It can be concluded that haplogroup J is a risk factor for AMD, whereas haplogroup H seems to be protective for AMD.

Complement factor H Y402H gene polymorphism and response to intravitreal bevacizumab in exudative age-related macular degeneration.

PURPOSE: To determine whether different complement factor H (CFH) genotypes play a role in treatment of age-related macular degeneration (AMD) with intravitreal bevacizumab. METHODS: In this prospective study, we included 197 patients with exudative AMD and treated with 1.25 mg intravitreal bevacizumab at 6-week intervals until choroidal neovascularization (CNV) was no longer active. In all patients, ophthalmological examinations, visual acuity, optical coherence tomography (OCT), fundus photography and fluorescein angiography were performed. Single nucleotide polymorphism (SNP) genotyping was performed using restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction (PCR) products. RESULTS: Age, gender and baseline mean visual acuity were similar among the three CFH genotypes. There was no significant difference in underlying lesion type of CNV, lesion size, number of injections or macula thickness. When examining the effect of genotype on post-treatment visual acuities, we observed a significant worse outcome for distance and reading visual acuity in the CFH 402HH genotype group. The number of patients who lost 3 or more lines in distance and reading visual acuity testing was significantly higher in the CFH 402HH (41%, 46%) genotype group than in patients with the CFH 402YY (28%, 26%) and CFH 402YH (26%, 24%) genotype. CONCLUSIONS: In addition to the higher risk for exudative AMD in patients with the CFH 402HH genotype that was found in previous studies, our results show that the CFH 402HH genotype also correlates with lower visual acuity outcome after treatment with bevacizumab, suggesting that pharmacogenetics of CFH plays a role in response to treatment of wet AMD.

Prevalence of impairment of visual function in European drivers.

PURPOSE: This study aimed to investigate the prevalence of impairment of visual function amongst European drivers. METHODS: A total of 2422 drivers from five European countries underwent a battery of visual function tests, including tests for visual acuity (VA), visual field (VF), contrast sensitivity, straylight (glare sensitivity) and useful field of view (UFOV). Subjects belonged to the following age categories: 45-54 years; 55-64 years; 65-74 years, and ≥ 75 years. A group of subjects aged 20-30 years served as a reference group. Results were compared with current standards for the visual function of drivers in the EU. RESULTS: Visual acuity in 0.5% of the younger group and 5.3% of the eldest group was below the standard required for driving. Visual acuity after proper refraction adhered to the standard in the majority of cases. Visual field results were below standard or questionable in 2.7% and 2.4%, respectively, of subjects in the eldest group. In this eldest group, impaired contrast sensitivity was present in 6.3%, increased glare sensitivity in 29.5% and impaired UFOV in 21.6% of subjects, but, as there are no standards for these criteria, the exact level of prevalence depends on the definition of impairment. CONCLUSIONS: Prevalences of impairment of visual functions that are not included in current standards (particularly contrast sensitivity and glare sensitivity) are much higher than prevalences of functions that are included (VA and VF).

Cataract and pseudophakia in elderly European drivers.

PURPOSE: To evaluate the prevalence and association of different types and severities of cataract or pseudophakia with visual impairments in older European drivers. METHODS: In this prospective European multicenter study, 2211 active drivers, 45 years of age and older, participated in an ophthalmologic examination, the measurement of visual functions, and were asked to fill in the NEI-VFQ-25 and another questionnaire about driving habits, driving difficulties, and self-reported accidents. RESULTS: Prevalence of moderate and severe forms of cataract in an active driving population is lower than that in the general population, but could be found in both eyes in 20% (95% confidence interval [CI] 16%-25%) and 17% (95% CI:13%-21%) of subjects 75 years of age and older. In addition, there is a strong relationship between severity of cataract and parameters such as age, visual acuity, intraocular straylight, and contrast sensitivity. CONCLUSIONS: Cataract is not as highly prevalent in the elderly active driving population as in the general population, but is frequently present in drivers over 65 years of age. Lower prevalence of severe bilateral cataracts in countries with mandatory tests of visual functions of drivers suggest that this could be a suitable measure to detect and to reduce the number of active drivers with severe bilateral cataracts.

Association of lens opacities, intraocular straylight, contrast sensitivity and visual acuity in European drivers.

PURPOSE: To study the relationship between lens opacity and intraocular straylight, visual acuity and contrast sensitivity. METHODS: We investigated 2422 drivers in five clinics in different European Union (EU) member states aged between 20 and 89 years as part of a European study into the prevalence of visual function disorders in drivers. We measured visual acuity [Early Treatment Diabetic Retinopathy Study (ETDRS) chart], contrast sensitivity (Pelli-Robson chart) and intraocular straylight (computerized straylight meter). Lens opacities were graded with the Lens Opacities Classification System III (LOCS) without pupillary dilation. Participants answered the National Eye Institute Visual Functioning Questionnaire - 25. RESULTS: Intraocular straylight was related more strongly to LOCS score than to both visual acuity and contrast sensitivity. Visual acuity and contrast sensitivity were correlated to each other well, but to intraocular straylight to a much lesser extent. Self-reported visual quality was best related to contrast sensitivity; night driving difficulty was best related to visual acuity. CONCLUSION: Straylight is found to have added value for visual function assessment in drivers, whereas if visual acuity is known contrast sensitivity has limited added value.

Straylight effects with aging and lens extraction.

PURPOSE: To assess possible gains and losses in straylight values among the population to consider straylight as added benefit of lens extraction. DESIGN: In this cross-sectional design, data from a multicenter study on visual function in automobile drivers were analyzed. METHODS: On both eyes of 2,422 subjects, visual acuity (logarithm of the minimum angle of resolution [logMAR] in steps of 0.02 log units), straylight on the retina (psychophysical compensation comparison method), and lens opacity (slit-lamp scoring using the Lens Opacities Classification System III [LOCS III] system) were determined. Three groups were defined: 220 pseudophakic eyes, 3,182 noncataractous eyes (average LOCS III score, <1.5), and 134 cataractous eyes (average LOCS III score, >3.0). RESULTS: Noncataractous straylight values increases strongly with age as: log(s) = constant + log(1 + (age / 65)(4)), doubling by the age of 65 years, and tripling by the age of 77 years. Population standard deviation around this age norm was approximately 0.10 log units. The cataract eyes (in this active driver group) had relatively mild straylight increase. In pseudophakia, straylight values may be very good, better even than in the noncataract group. Visual acuity and straylight were found to vary quite independently. CONCLUSIONS: Lens extraction holds promise not only to improve on the condition of the cataract eye, but also to improve on the age-normal eye. Lens extraction potentially reverses the strong age increase in straylight value, quite independently from visual acuity.