Melatonin and Sleep-Wake Rhythms before and after Ocular Lens Replacement in Elderly Humans.

Light of short wavelengths has been shown to play a key role in non-image forming responses. Due to aging, the ocular lens becomes more yellow reducing the transmission of short wavelengths in the elderly. In the present study, we make use of cataract surgery to investigate the effects of a relative increase of short wavelength transmission on melatonin- and sleep-wake rhythms (N = 14).

Light damage to the retina: an historical approach.

A brief review of retinal light damage is presented. Thermal damage requires a local rise in temperature of at least 10 °C, causing an instant denaturation of proteins. The primary absorber is melanin.

The action spectrum of photochemical damage to the retina: a review of monochromatic threshold data.

Photochemical damage to the retina occurs for prolonged exposures of intense light. Two action spectra exist for this phenomenon. In rat an action spectrum matching the absorption spectrum of rhodopsin was found.

Directional model analysis of the spectral reflection from the fovea and para-fovea.

Directional and nondirectional spectral reflection data from 0, 1, 2, 4, and 8 deg eccentricity, and the optic disk, were analyzed from 400 to 950 nm with an existing optical reflection model. The optical model, developed for the fovea, appeared to be also suitable for more eccentric locations. The optical densities of melanin and of the macular pigments zeaxanthin and lutein peaked in the fovea, in correspondence with literature data.

In vivo quantification of the retinal reflectance spectral composition in elderly subjects before and after cataract surgery: Implications for the non-visual effects of light.

Light is the signal that entrains the biological clock in humans to the 24-hour external time. Recently, it has been shown that short wavelengths play a key role in this process. In the present study, we describe a procedure to measure, objectively and in a quick way, the spectral composition of the light reaching the retina in vivo.

Foveal cone photoreceptor involvement in primary open-angle glaucoma.

Background: To test whether foveal cone photoreceptors are impaired in primary open-angle glaucoma (POAG).

Methods: Nineteen POAG eyes with central glaucomatous visual field defects, and 34 age-matched control eyes were included. Fundus reflectometry, together with a model fit procedure, provided information on a set of parameters: lens optical density, macular pigment optical density, melanin, blood, the directional cone reflectance (Rd), a measure for foveal cone photoreceptor integrity, and RILM, the reflectance at the inner limiting membrane.

Lutein and zeaxanthin measured separately in the living human retina with fundus reflectometry.

Purpose: To separately measure the optical densities of lutein (L) and zeaxanthin (Z) in the human retina in vivo. L and Z are the basic constituents of the macular pigment (MP).

Methods: Spectral fundus reflectance was measured in 23 subjects (group 1) at 0 degrees , 1 degrees , 2 degrees , 4 degrees , and 8 degrees eccentricity with a modified macular pigment reflectometer.

Directional and nondirectional spectral reflection from the human fovea.

A model of the directional and nondirectional reflection spectrum of the human fovea is developed, incorporating reflectors, absorbers, and a wavelength-dependent optical Stiles-Crawford effect (OSCE). Data from 102 healthy subjects between 18 and 75 years obtained with the fundus reflection analyzer (FRA), an imaging spectrograph that measures the directional reflection profile of the human fovea in the pupil plane from 400 to 950 nm, were analyzed. Subgroups of young (<40 years) and old (>50 years) observers were defined.

Foveal cone-photoreceptor integrity in aging macula disorder.

Purpose: To establish the relation between AMD stage and a quantitative measure for the integrity of foveal cone photoreceptors related to the optical Stiles-Crawford effect.

Methods: Fifty-six AMD eyes and 57 control eyes were included in the final analysis. AMD was graded in accordance with the International Classification System into five mutually exclusive stages.

Spectral transmission of intraocular lenses expressed as a virtual age.

Aim: Currently available intraocular lenses (IOL) have widely different spectral filters. This study aimed to calculate the virtual age of IOL with regard to photoprotection and photoreception, i.e.

Optical density of the aging human ocular media in the visible and the UV.

We analyzed the literature on the absorption in the young and aging human eye media. Five templates were derived to provide an adequate description of the spectra from 300 to 700 nm for the lens, cornea, aqueous, and vitreous. Two templates were found in all media.

Sharp cutoff filters in intraocular lenses optimize the balance between light reception and light protection.

Purpose: To facilitate the selection of the spectral filter in intraocular lenses (IOLs).

Setting: Department of Ophthalmology, University Medical Center Utrecht, Utrecht, The Netherlands.

Methods: The spectral transmission of commercially available IOLs was measured, and information from manufacturer data sheets and the literature was gathered.

Interocular agreement in melanin and macular pigment optical density.

Macular pigment (MP) and melanin possibly protect the macular area by absorbing blue light and acting as antioxidants. Because little is known about the interocular correlation of melanin, we determined its optical density (MOD) in both eyes of healthy subjects using fundus reflectometry. The measuring method also provided optical densities of MP (MPOD).

Fast assessment of the central macular pigment density with natural pupil using the macular pigment reflectometer.

We built a new macular pigment reflectometer (MPR) for fast and objective measuring of the optical density of macular pigment in the human eye, using the undilated eye. The design is based on the spectral reflectance from a spot of white light at the fovea. To evaluate its performance, we measured the macular pigment of 20 healthy subjects, ages 18 to 79 years, under four conditions: (1) natural pupil in the dark, (2) natural pupil with dim room light, (3) dilated pupil in the dark, and for comparison with a different technique, (4) heterochromatic flicker photometry (HFP) in dim room light with natural pupil.

Retinal degeneration and ionizing radiation hypersensitivity in a mouse model for Cockayne syndrome.

Mutations in the CSB gene cause Cockayne syndrome (CS), a DNA repair disorder characterized by UV sensitivity and severe physical and neurological impairment. CSB functions in the transcription-coupled repair subpathway of nucleotide excision repair. This function may explain the UV sensitivity but hardly clarifies the other CS symptoms.

Influence of macular pigment and melanin on incident early AMD in a white population.

Background: The protective effect of macular pigment (MP) and melanin against age-related macular degeneration (AMD) is still controversial from cross-sectional studies. In an attempt to clarify this issue, we performed a population-based longitudinal study.

Methods: MP optical density (MPOD) and melanin optical density (MOD) data were collected during the second follow-up phase of the Rotterdam Study in 1999 in a random subset of 435 participants.

Macular pigment shows ringlike structures.

Purpose: The spatial distribution of macular pigment is generally assumed to monotonously decrease to very low values in the periphery. However, there are indications that this picture may be too simple. The purpose of this study was to examine the spatial distribution of the macular pigment optical density.

Retinal damage by optical radiation. An alternative to current, ACGIH-inspired guidelines.

Background: The ACGIH guidelines for protection against retinal damage by optical radiation are often difficult to apply due to their lack of transparency. The less known guidelines by the Netherlands Health Council (HCN), dating from 1978 and updated in 1993, might offer a way out in many cases.

Methods: A comparison is made of these guidelines, embedded in a short sketch of the history.

A yellow ring-shaped macular reflection.

Purpose: To describe a yellow ring-shaped reflection in the macula of healthy subjects observed with a common indirect ophthalmoscope.

Design: Observational case series.

Methods: Fundus photographs of the macula were acquired with a slit lamp and 90-diopter lens in 5 healthy subjects (age range, 23-50 years) at a perpendicular angle and at an oblique angle to the retina.

On the age dependency of the macular pigment optical density.

Macular pigment may protect against age related macular degeneration (AMD), because of its capability to absorb blue light and scavenge free radicals. Since age is the major risk factor in AMD, a fundamental question to be answered is the possible age dependence of the macular pigment optical density (MPOD) in normal healthy subjects. In this study we used five methods to study a possible age effect: heterochromatic flickerphotometry, two setups for fundus reflectance spectroscopy, a Scanning Laser Ophthalmoscope (SLO) for obtaining reflectance, and the same SLO for autofluorescence maps.

Spectral and directional reflectance of the fovea in diabetes mellitus: photoreceptor integrity, macular pigment and lens.

Our aim was to assess the integrity of the photoreceptors in the fovea, and to measure the optical density of the macular pigment and the eye lens in patients with diabetes mellitus, and to compare the results with those of a group of healthy subjects. The directional and spectral properties of the light reflected from a 1.9 deg field centered on the fovea were measured simultaneously, in a single one second flash, with the Foveal Reflection Analyzer.

Absorption of the eye lens and macular pigment derived from the reflectance of cone photoreceptors.

We measured the amplitude of the directional component of the bleached fundus reflectance, the so-called optical Stiles-Crawford effect, as a function of wavelength. The directional reflectance originates from within the outer segments of the photoreceptors. Thus only two anterior absorbers are of importance: macular pigment and the crystalline lens.

Thermal cataract, from furnaces to lasers.

Background: Thermal cataract has long been known as an occupational disease in furnace workers. This affliction has virtually disappeared in western countries due to improved working conditions. However, new light sources have appeared on the scene, in particular lasers, which might also be capable of producing thermal cataract.