Martijn J. Kanis

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. A model generated the optical densities of L (LOD) and Z (ZOD), using their slightly different absorption spectra. Three other subjects (group 2) took 20 mg/d zeaxanthin for 6 months; they were measured approximately monthly for 18 months. RESULTS Mean LOD for group 1 at the central fovea was 0.200 +/- 0.061 (range, 0.085-0.305), mean ZOD was 0.494 +/- 0.169 (range, 0.169-0.806), resulting in a mean Z fraction [ZOD/(LOD + ZOD)] of 0.71. ZOD dropped faster toward the periphery than LOD, measuring 0.044 and 0.010 (Z fraction 0.18) at 8 degrees , respectively. Zeaxanthin supplementation in group 2 caused a significant increase in ZOD, and no or minor changes in LOD. ZOD further increased over a 10-month period after supplementation in all subjects. CONCLUSIONS LOD and ZOD had different spatial profiles that, apart from scaling factors, showed similarity to in vitro literature data. Supplementation with Z caused LOD to decrease and ZOD to increase. These results strongly suggest that the optical densities of L and Z can be assessed in vivo by fundus reflectometry, opening new ways of investigating the putative protective roles of L and Z in retinal disease.

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. Stages 0 to 1 were labeled no AMD, stages 2 to 3 were labeled early AMD, and stage 4 was labeled late AMD. Fundus reflectometry, together with a model-fit procedure, provided information on directional cone reflectance (Rd), a quantitative measure for the integrity of foveal cone photoreceptors. Optical densities of macular pigment (MPOD) and melanin (MOD) were also obtained. A general linear model analysis was used to compare Rd, MPOD, and MOD among the AMD stages. RESULTS Mean Rd was lower in early AMD (0.92%, P < 0.001) and late AMD (0.86%, P < 0.001) compared with mean Rd in the no-AMD stage (1.76%). Mean MPOD was not different in early AMD (0.53, P = 0.05), but it was lower in late AMD (0.19, P < 0.001) compared with mean MPOD in the no-AMD stage (0.42). Mean MOD was lower in early (1.09, P = 0.001) and late (1.01, P = 0.004) AMD compared with mean MOD in the no-AMD stage (1.23). CONCLUSIONS Foveal cones show signs of misalignment and/or outer segment deterioration in early AMD. Melanin rather than macular pigment may play a protective role against AMD, although loss of these ocular pigments can also be caused by AMD.

Integrity of foveal cones in multiple evanescent white dot syndrome assessed with OCT and foveal reflection analyser

In this report, foveal photoreceptor involvement in a case of multiple evanescent white dot syndrome (MEWDS) is described by using two optical techniques: optical coherence tomography (OCT) and foveal reflection analysis (FRA). OCT showed a transient disruption of the foveal photoreceptor outer segments. FRA, a recently developed quantitative technique, showed disarray of the foveal cones. A 20 year old myopic Sudanese female presented at our hospital with a central visual field defect of her right eye, associated with photopsia. Visual acuity was 0.3; intraocular pressure was 16 mm Hg. Funduscopic examination of the affected eye showed some pigment epithelial alterations in the macular area, with an irregular macular reflex. Upon visual field examination, the affected eye showed a 12 dB decrease in central sensitivity, and a small blind spot enlargement was seen. No such changes were found in the left eye. OCT showed degeneration or disarray of foveal photoreceptor outer segments in the …

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. The instruments involved are the foveal reflection analyzer (FRA) and the macular pigment reflectometer (MPR). By making use of these reflectometers, we show quantitatively that in subjects with cataracts, the light input is especially reduced in the short wavelength range. After cataract surgery during which the crystalline lens is replaced by a transparent artificial lens, the transmittance of the short wavelengths (between 420-500 nm) improved on average by a factor of 4. We conclude that this technique holds great promises for the chronobiological field because it allows for quantification of the spectral composition and light levels reaching the retina in vivo.

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. The amplitude of the directional component, originating in the cone photoreceptors, had its maximum at 1 deg. The maximum of the directionality (peakedness) occurred at a slightly higher eccentricity.

Delayed recovery of the optical Stiles–Crawford effect in a case of central serous chorioretinopathy

We describe the 1-year follow-up of a 35-year-old white woman who presented with acute central serous chorioretinopathy (CSC) affecting her left eye. We evaluated best corrected visual acuity, optical coherence tomography (OCT) and optical Stiles–Crawford effect. Visual acuity had recovered 7 weeks after onset. Subretinal fluid had disappeared on OCT after 32 weeks, but OSC effect was only within normal limits after more than a year. This points to delayed recovery of the foveal cone photoreceptor directionality in CSC. Thus CSC has a more profound effect on foveal cones than shown with common diagnostic techniques. A 35-year-old woman with recently diagnosed central serous chorioretinopathy (CSC) of her left eye participated in a study on the optical Stiles–Crawford effect (SCE) in this well known pathology. Two weeks earlier she had …

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). We observed, on average, a delay of the sleep-wake and the nocturnal melatonin rhythms after cataract surgery. This delay is tentatively attributed to a relatively large increase of light transmittance in the evening hours more than an increase of the already relatively high light intensities found in the daytime. The later phase that we observed after cataract surgery (clear lens) as compared to the earlier phase observed before cataract (yellowish lens) is in agreement with the general later phase reported in the young (clear lens) population.

Macular pigment and fixation after macular translocation surgery

Background After full macular translocation (MT) surgery with 360° retinotomy, the fovea is rarely identifiable. Our aim was to verify the position of the fovea, to determine how patients fixate after MT and to examine distribution and optical density of macular pigment (MP). Methods 9 patients after MT were investigated. The Utrecht Macular Pigment Reflectometer was used to quantify the MP optical density. A scanning laser ophthalmoscope (SLO) was used to identify the fovea as the centre of MP distribution and determine the retinal locus of fixation. Results In all patients, the fovea was identified as the centre of MP distribution. The retinal areas used for fixation were displayed by SLO fixation analysis. Comparing their spatial relationship with the fovea, five patients fixated centrally and four eccentrically up to 7.5°. In those patients, microperimetry showed that the atrophy caused by choroidal neovascularisation (CNV) extraction prevented central fixation. Conclusion The combination of MP distribution and fixation analysis allows fixation behaviour to be quantified, even if the fovea morphologically cannot be localised. Our results suggest that the scotoma caused by spreading chorioretinal atrophy is the main cause for reduced visual acuity after MT, and so the MT rotation angle is crucially important.