At least 700 carotenoids are found in nature. Around 50 are included in a typical human diet, 15–16 of which make their way to the circulatory system, but remarkably only three are found in the eye, where they are highly concentrated at the macula.

These yellow macular pigments—lutein, zeaxanthin and meso-zeaxanthin—have powerful antioxidant properties and play essential roles in filtering high-energy, short-wavelength blue light and in minimising the oxidative stress that is known to be a significant factor in age-related eye disease.

Prof. John Nolan of the Nutrition Research Centre Ireland has spent 20 years researching the macular pigments—measuring them and monitoring their effects on health. He says that “the general population is highly deficient in these three carotenoids; even the healthiest person you know is deficient. Nobody is eating enough.” A deficiency in macular pigments has a real and tangible impact on day-to-day quality of life in terms of vision and cognitive function.

Everybody who works in eye care is aware that visual acuity does not describe the whole of visual performance, which is multifaceted and also incorporates aspects of processing speed, contrast sensitivity, glare and visual adaptation. Prof. Nolan’s European CREST trials, supported by a European Research Council Starting Grant, demonstrated that each of these individual visual functions is significantly improved by enriching the macular pigments by means of an oral supplement, not only in subjects with early age-related macular degeneration but also in healthy subjects.

Blue light is a problem for visual performance and increasing its filtration—by increasing macular pigment—reduces visual discomfort and glare disability and improves photostress recovery. Another important aspect of vision is the speed of visual processing, which is strongly modifiable by increasing macular pigment.

For every 0.1 increase in macular pigment optical density, roughly 1 millisecond of reaction time can be gained.

 Increased contrast sensitivity can hugely improve a patient’s quality of life and how they feel about their vision. A patient with a medium or high level of macular pigments can of course still develop macular degeneration, but nutrition can counterbalance genetic factors and optimise their individual disease trajectory.

It is important to measure the concentration of macular pigment in the eye itself because retinal levels correlate only weakly with levels measured in the blood; availability of the fat-soluble carotenoids at their target tissue depends on a subject’s body mass index amongst other factors. Until fairly recently, it has been possible to quantify retinal concentrations using psychophysical methods only, which are known to be highly subjective and variable and also have the disadvantage of measuring at only one point in the eye.

Prof. Nolan has worked with Heidelberg Engineering to develop an experimental software add-on to the Spectralis system, which uses a dual-wavelength autofluorescence system to measure the “optical volume” of the macular pigments (see Figure 1).

 They have developed and validated macular pigment optical volume (MPOV) as an arbitrary unit that provides a measure of the concentration of the pigments within every pixel of the image, across the entire macula, thus allowing the distribution of the pigments to be mapped.

It is now possible to examine a patient and compare their MPOV with that of the general population average in terms of low or high levels of pigment. Most people have around 2000–3000 MPOV, but with appropriate supplementation it is possible to increase that value to 7000–10,000 MPOV. 

 The effects of this increase in MPOV primarily manifest as improved contrast sensitivity rather than a change in visual acuity.

Prof. Nolan’s current research interest is dementia and cognitive function. It has become clear that the levels of macular pigment measured in the eye correlate with their levels in the brain; it has been demonstrated further that these levels correlate directly with cognitive function.

The population of people with Alzheimer’s disease is the most deficient Prof. Nolan has encountered and he is currently conducting an interventional study in these patients. This would not have been possible previously, as people with this dementia are not able to cooperate with psychophysical testing. The Spectralis system makes it possible to quickly and simply measure their macular pigment.

A cross-sectional observation study with 4,000 participants in the Republic of Ireland demonstrated that people who had high levels of pigment outperformed everybody else in all measures of cognitive abilities.

 This was followed with interventional trials, which found that memory and cognition in healthy patients improved on supplementation with the three macular pigments.

It is possible in principle to improve one’s levels of macular pigment by eating significant portions of plants such as spinach, kale and corn. Good nutrition is a baseline and the first step Prof. Nolan takes with his trial subjects is to optimise their nutritional profile via diet.

He said, “I came into this exercise very anti-supplement. I did experiments with hens to try to make eggs the solution; I did smoothie trials; I tried to make food the solution.” However, an affordable supplement purified from Mexican marigolds

, which are rich in the carotenoids of interest, is now readily available

“We have had success with things like folic acid that pregnant people or those planning babies take—for me, this is another example of a nutrient we should all be taking,” Prof. Nolan explained. Colostrum is yellow because of these nutrients and mothers become highly deficient in these carotenoids during pregnancy, showing that nature wants us to have these pigments that affect retinal and brain development right from birth.

A cost–benefit analysis that Prof. Nolan published in the

showed clearly that across a 5-year period, in the population of the Republic of Ireland, using these supplements as standard could save over 250 million Euros from the health budget.

In summary, “thanks to Heidelberg Engineering we have an imaging system that empowers ophthalmology and optometry to take measurements that are truly valuable to measures of nutrition that are working throughout our lifetime.”

Prof. Nolan of the Nutrition Research Centre Ireland, School of Health Science, Waterford Institute of Technology, was recently awarded the Heidelberg Engineering Xtreme Research Award 2020 for his research on macular pigment for vision health and as a biomarker for brain nutrition and function. He has no financial interest in the subject of this article.

Akuffo KO, Beatty S, Peto T, et al. The impact of supplemental antioxidants on visual function in nonadvanced age-related macular degeneration: a head-to-head randomized clinical trial. 

Nolan JM, Power R, Stringham J, et al. Enrichment of macular pigment enhances contrast sensitivity in subjects free of retinal disease: central retinal enrichment supplementation trials – report 1. 

Bovier ER, Hammond BR. A randomized placebo-controlled study on the effects of lutein and zeaxanthin on visual processing speed in young healthy subjects. 

Green-Gomez M, Bernstein PS, Curcio CA, et al. Standardizing the assessment of macular pigment using a dual-wavelength autofluorescence technique. 

Feeney J, O’Leary N, Moran R, et al. Plasma lutein and zeaxanthin are associated with better cognitive function across multiple domains in a large population-based sample of older adults: findings from the Irish longitudinal study on aging. 

Articles

Dietary macular pigments, which can now be measured directly and accurately, are hugely important in optimising visual function, especially as we age.

Dietary supplement improves measurable visual outcomes

The use of scleral contact lenses has grown significantly in the past year, with an associated exponential increase in research.

 This type of lens can be classified as corneo-scleral or fully scleral depending on the presence or absence of corneal bearing.

One of the main advantages of this option for refractive correction is that the tear reservoir between the posterior surface of the contact lens and the anterior corneal surface allows a significant neutralisation of anterior corneal aberrations, which are relevant considering the contribution of this optical surface to the total power of the eye.

As these lenses are fitted with minimal or no corneal bear, the fitting process can be simplified in patients with highly irregular anterior corneal profiles.

 For this reason, the use of these contact lenses has been intensively investigated for the correction of irregular astigmatism in post-corneal refractive surgery

 as well as in ectatic corneal disorders.

Although there is a consensus among practitioners with more than 5 years of scleral lens experience about most of the aspects of contact lens management,

 there are some factors that require more research, such as the management of multifocality for presbyopia correction. To date, only the outcomes of conventional soft or rigid gas-permeable corneal contact lenses have been evaluated,

 despite the availability of some multifocal scleral lens designs.

Recently, a new model of multifocal corneo-scleral contact lens has been commercially released by Laboratorios Lenticon S.A., Presbycustom, providing the option of customising not only the fitting parameters to adjust the lens over the cornea and sclera, but also the type of multifocality induced. We report here the results obtained with this new modality of multifocal scleral contact lens in eyes with previous refractive surgery and significant high-order corneal aberrations.

The Presbycustom contact lens (paflufocon D, Dk 100 Fatt units) is the result of a proof-of-concept research project developed by Laboratorios Lenticon SA in collaboration with the Group of Optics and Visual Perception of the University of Alicante.

 It is a corneo-scleral contact lens made of highly gas-permeable material.

The lens is customised according to the anterior corneal geometry, the level of ocular high-order aberrations and the peculiarities of pupil dynamics. It comprises three different areas: corneal, limbar and scleral (

The corneal area has a variable diameter with fixed back surface asphericity and central anterior surface asphericity that is modified according to the aberrometric induction required. Specifically, the depth of focus achieved with the contact lens is set by customising the induction of primary and secondary spherical aberration. It has been demonstrated that combining primary and secondary spherical aberrations of opposite sign is significantly more effective for expanding the depth of focus than other aberrometric options.

The scleral area of the contact lens allows a smooth bearing over the sclero-conjunctival surface, facilitating comfortable wearing (

). The distribution of the tear film below the different areas of the contact lens generates a characteristic fluorogram consisting of central tear pooling with paracentral alignment and significant edge clearing (

We recently conducted a prospective pilot study in the Department of Ophthalmology of the Vithas Medimar International Hospital (Alicante, Spain) and the Optometry Clinic of the University of Alicante including eight eyes of eight patients (aged 45 to 56 years) with previous LASIK surgery requiring presbyopia correction. All cases had reduced corrected distance visual acuity (CDVA) and significant corneal irregularity.

A complete ocular examination was performed before and 1 month after fitting the customised multifocal scleral contract lens, including visual and refractive analysis, corneal topography, pachymetry and evaluation of corneal and ocular aberrations with the VX120 multidiagnostic system (Luneau Technologies). The contact lens was customised according to the anterior corneal geometry, the level of ocular high order aberrations and the pupil diameter.

The mean corneal radius of the lens fitted was 8.06 ± 0.47 mm; the mean scleral radius was 7.68 ± 0.20 mm. The mean central eccentricity used for the lenses was 0.44 ± 0.33, whereas a fixed posterior eccentricity of 0.63 was used in all contact lenses fitted.

Mean monocular logMAR CDVA changed from 0.21 ± 0.08 with spectacles before fitting to 0.08 ± 0.08 with contact lens fitted (

 = 0.04). Mean logMAR binocular distance and near visual acuity values with the contact lens were 0.02 ± 0.03 and 0.14 ± 0.11. Mean logMAR-corrected visual acuities for defocus levels of –0.50, –1.00, –1.50, –2.00 and –2.50 D were 0.03 ± 0.06, 0.08 ± 0.08, 0.19 ± 0.17, 0.24 ± 0.10 and 0.31 ± 0.12, respectively (

All patients reported spectacle independence for reading and high levels of contact lens tolerance and satisfaction. No complications were reported during the first year of follow-up.

The selection of an appropriate combination of primary and secondary spherical aberration of opposite sign according to the aberrometric status of the eye can be useful to optimise the depth of focus required for presbyopia correction. This approach can be used to correct presbyopia in irregular corneas with a scleral contact lens.

This pilot study shows that complete visual rehabilitation can be achieved with a customised multifocal scleral lens in presbyopic eyes with previous unsuccessful corneal refractive surgery. These preliminary results should be corroborated in the long term as well as in a larger population.

Dr Piñero is based in the Department of Optics, Pharmacology and Anatomy, University of Alicante, Spain. He has no proprietary or commercial interest in the device described. This research was co-funded by Laboratorios Lenticon S.A. and the University of Alicante within the proof of concept project PC15-02 “Diseño de lente de contacto escleral multifocal personalizada (Presbycustom).” Dr Piñero is also supported by the Ministry of Economy, Industry and Competitiveness of Spain within the programme Ramón y Cajal, RYC-2016-20471.


Davies I. Scleral publications & contact lens category growth. 

Van der Worp E, Bornman D, Ferreira DL, et al. Modern scleral contact lenses: A review. 

Piñero DP. Management of keratoconus with scleral contact lenses. In: Barbara A, ed. 

Controversies in the Management of Keratoconus

. Cham, Switzerland: Springer Nature Switzerland AG. 2019.

Porcar E, España E, Montalt JC, et al. Post-LASIK visual quality with a corneoscleral contact lens to treat irregular corneas. 

Piñero DP. Full scleral lens fitting in an eye with high corneal astigmatism after radial keratotomy and several retreatments. 

Barnett M, Lien V, Li JY, et al. Use of scleral lenses and miniscleral lenses after penetrating keratoplasty. 

Serramito-Blanco M, Carpena-Torres C, Carballo J, et al. Anterior corneal curvature and aberration changes after scleral lens wear in keratoconus patients with and without ring segments. 

Piñero DP. Fitting of a new design of full scleral contact lens in advanced keratoconus with previous implantation of intracorneal ring segments. 

Harthan J, Nau CB, Barr J, et al. Scleral lens prescription and management practices: the SCOPE study. 

Pérez-Prados R, Piñero DP, Pérez-Cambrodí RJ, Madrid-Costa D. Soft multifocal simultaneous image contact lenses: a review. 

Piñero DP, Carracedo G, Ruiz-Fortes P, Pérez-Cambrodí RJ. Comparative analysis of the visual performance and aberrometric outcomes with a new hybrid and two silicone hydrogel multifocal contact lenses: a pilot study. 

Piñero DP, Tolosa A, Camps VJ, et al. Patent: “Lente de contacto multifocal scleral,” application number: P201631236, 21 September 2016.

Yi F, Iskander R, Collins M. Depth of focus and visual acuity with primary and secondary spherical aberration. 

Benard Y, López-Gil N, Legras R. Optimizing the subjective depth-of-focus with combinations of fourth- and sixth-order spherical aberration. 

A multifocal corneo-scleral contact lens that can correct presbyopia in irregular corneas has undergone a small pilot study. Complete visual rehabilitation was achieved along with a high degree of patient satisfaction.

Ophthalmology Times Europe November 2020

Dietary supplement improves measurable visual outcomes

Multifocal lenses for presbyopia in eyes with previous corneal surgery