Reading the greens: Golf, vision, and nutrition

Optometrists have several options to help recreational and competitive golfers enhance their visual performance on the golf course. Optometrists should provide optimal vision correction and assist patients with a decision about sun eyewear for golf. (Adobe Stock / Tawan)

Recreational and competitive athletes continuously search for ways to elevate their performance. In golf, a defining element of top golfers is the ability to read the contours of the green and determine the best trajectory for a successful putt. This element of golf performance is essentially a visual task, but few golfers or optometrists consider vision skills as an important factor for success in the sport.

The logical focus for performance improvements is typically in methods to enhance physical factors, such as strength and conditioning training regimens, biomechanical factors, rest and recovery programs, and psychological preparation. Although these methods are certainly important considerations, the option to improve visual performance can be a neglected element in the preparation for competition.

Table 1

When putting, many visual skills may affect a golfer’s read of the green, putting alignment, and distance assessment. Coffey et al reported that ocular gaze and head position influence fixation disparity and heterophoria.¹ Previously, Coffey et al found that instability of binocular visual alignment is related to errors in putting alignment.² In another study, Coffey et al reported that contrast sensitivity, visual acuity, and stereopsis tend to be better in professional players than in amateurs.³

Similar differences were found when younger players were compared with golfers with presbyopia. Eye care professionals can offer several visual care services to help competitive athletes enhance these visual performance factors (Table 1).

Refraction

Table 2

The process begins with a good case history and careful refraction to understand the options to enhance visual performance on the golf course. Understanding the patient’s visual difficulties on the golf course will direct the services that can be offered. The subjective refraction should continue to the best visual acuity because many golfers may have acuity of 20/10 or better. We advocate the following prescribing guidelines (Table 2).⁴

Myopia. Golfers with myopia of –0.25 D or more should be counseled on the possible benefits of refractive correction.

Astigmatism. Astigmatism has a similar effect on visual resolution as myopia, especially against-the-rule and oblique astigmatism. Refractive compensation should be considered with astigmatism of 0.5 D or more, although with-the-rule astigmatism compensation may not yield as much improvement on clinical measures.

Hyperopia. Low amounts of hyperopia are often well tolerated without correction; however, hyperopia of 1 D or more may require a significant amount of effort from the golfer to achieve and maintain clarity. Judicious refractive compensation may reduce the accommodative effort needed for the golfer to achieve optimal image clarity.

Anisometropia. Low amounts of anisometropia are not always compensated for, especially when refractive errors are low. Anisometropia of 0.5 D or more can have a detrimental effect on depth perception, and some golfers may be sensitive to that effect. Additionally, the effects of meridional anisometropia should be considered in athletes with asymmetric astigmatism. Balancing the image quality through refractive compensation will enhance sensory fusion and improve the quality of spatial localization judgments—important factors for reading the greens.

The athlete can make the decision about whether to experiment with a prescription, but these guidelines can be useful to help initiate a discussion. Ultimately, the preference is to achieve optimal visual acuity and contrast sensitivity.

Filters

Because contrast sensitivity, visual acuity, and stereopsis are better in higher-level golfers, reduced visual information due to the filter effects of some eyewear may negatively affect putting performance. Farnsworth and Smith reported that “most players did not believe sunglass tints improved golf performance, despite acknowledgment that wearing sunglasses reduced visual fatigue.”⁵ In fact, almost all the top golfers do not wear sunglasses when putting, despite brand endorsement deals.

Premium sports eyewear was found to have significant amounts of prism in both primary and lateral gaze.⁶ Results from another study found that prismatic effects induced by the lens design of sun eyewear were noticed by golfers.⁷ Contributing factors to prismatic effects include the steep front and back lens curves, the tilt of the lens, lens thickness, and manufacturing abnormalities (eg, induced distortion).

Prismatic effects induced by eyewear designs may affect the golfer’s ability to judge depth and location. For example, with yoked horizontal prisms, the image will be displaced laterally. However, if the prisms are oriented in opposing horizontal directions, both the perceived size and distance of the object will appear to change. Changes in lateral displacement or in apparent size and distance may cause critical errors in putting performance.

Sports vision training

Sports vision training (SVT) programs are typically designed to provide practice with demanding visual, perceptual, and sensorimotor tasks, with the goal of improving performance. There is limited and mixed support demonstrating that traditional SVT procedures can improve sports-relevant vision or manifest into better on-field performance.⁸ However, isolating one area of intervention as solely responsible for any changes in performance is quite difficult. Many reports in the literature are anecdotal, and many studies have significant flaws in the research design that preclude a definitive judgment.

Nutrition options

An overlooked option to improve visual performance is nutrition. In addition to the role nutrients play in age-related changes to ocular tissues, there has been significant research into the effects on visual performance in young, healthy individuals.

Specifically, zeaxanthin (Z) and lutein (L) are plant-derived carotenoids that are concentrated in the eye and brain. L and Z are concentrated within the inner plexiform, outer plexiform, and outer nuclear layers of the retina, specifically at the Henle fiber layer, and act as a filter for light.^9,10 The concentration of these carotenoids is overtly visible as a yellow spot in the macula, and its measurement can easily be performed clinically.^11,12 Our understanding of the carotenoids and its effects on ocular and systemic physiology is greatly benefited not only by evaluating healthy individuals but also by disease states.^13-19

Visual effects

A systematic review and meta-analysis found evidence from placebo-controlled, double-blind clinical trials that the density of the macular pigment has an effect on glare disability and discomfort, photostress recovery, and contrast enhancement.²⁰ Less discomfort and glare disability are reported from short-wavelength light in those with a higher concentration of macular pigment.^21,22 Supplementation with L and Z has shown an improvement in glare disability that was proportional to the level of macular pigment increase.^22-24

The same trend can be seen with photostress recovery following exposure to bright light and visual discomfort.^23,24 These results are consistent with recent findings in an older population who consumed a carotenoid vitamin supplement with L, Z, and other phytochemicals.²⁵ The ability to perform optimally under intense glare conditions may be improved by increasing macular pigment density. This is particularly important in golf because glare and variable shadows can significantly increase the difficulty in reading the green.

Recent research has demonstrated a linear relationship between macular pigment density and contrast enhancement.²⁶ Because the macular pigments selectively filter short-wavelength light, it has been proposed that those with a higher density of macular pigments have an expanded visible range (approximately 30%) due to the preponderance of short-wavelength light in the atmosphere.²⁷ Therefore, the ability to detect a golf ball against a blue sky is enhanced with increasing macular pigment.

Although the effect of carotenoid supplementation on color vision has not been directly examined in golfers, a prior report has shown that in individuals with type 1 or type 2 diabetes, color vision can be enhanced using a carotenoid vitamin supplement rich in L and Z.²⁸ Results from these studies make a strong case for L and Z supplementation and benefits/improvements in visual functions that could be particularly important in golf.

Neural effects

Although the presence of L and Z in the macula is well recognized, these carotenoids also concentrate in the brain. Randomized, double-masked, placebo-controlled clinical trials of young, healthy patients have shown that macular pigment density is linked to L and Z levels in the brain,²⁹ and the level present is related to functions such as cognition, reaction time, and temporal visual processing.^30-32 L and Z are incorporated in cell membranes and axonal projections, which enhance interneuronal and neuroglial communication.³³

Recently, supplementation with carotenoids has been shown to increase critical flicker frequency thresholds, visual-motor reaction time, and temporal contrast sensitivity function compared with a placebo control group, improving processing speed by an average of 10% to 20%.^31,32 Nutritional support for cognitive function may be an additional long-term benefit for golfers.

Athlete recommendations

To help golfers achieve optimal visual performance, recommendations should include modifications to diet to increase intake of carotenoids or supplementation with purified forms of L and Z. Results from placebo-controlled studies have found that macular pigment density can be increased by an average of approximately 20% with supplementation.^21,22

Recent studies have used 10 to 20 mg of dietary Z in the supplements for those who are young and healthy compared with lower concentrations for age-related conditions (the Age-Related Eye Disease Study 2 formula has only 2 mg of Z).^23,31,32 For competitive athletes, care should be taken to recommend supplements that have been certified for content, especially to avoid substances banned in sports.

We recommend checking the National Sports Forum website to identify supplements that are certified for sports (https://www.nsfsport.com). In addition to the visual and cognitive performance improvements found with supplementation, evidence exists that L and Z have protective effects for the retina from photo-oxidative damage.

Summary

Optometrists have several options to help recreational and competitive golfers enhance their visual performance on the golf course. Optometrists should provide optimal vision correction and assist patients with a decision about sun eyewear for golf. For those golfers who experience difficulties with glare, photostress, and contrast judgment, increasing macular pigment density offers another potential method to improve these functions by enriching natural physiology.

Many golfers prefer to remove any sun eyewear when reading the green and putting. Improved macular pigment density can help with glare disability and when moving between bright light and shadow. It may be that improvement in L and Z concentrations in the macula can provide enhanced visual function without the reduction in overall luminance that occurs with external filter use. It is likely that many golfers have not received information about the potential benefits of increasing carotenoid intake or supplementation.

Optometrists can provide information to help patients understand the role these nutrients play in the health and performance of their eyes and offer guidance on effective use of supplements.

This article has focused on the options for improving visual performance in golfers; however, these improvements may be applied to many other patients. Improving visual performance would clearly be advantageous to many daily activities, such as driving or playing video games. There are potential benefits for those in occupations such as law enforcement, firefighting, piloting, and the military. Optometrists have many options to help optimize visual performance for all patients.

References

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