Abstract
Purpose: :
To compare the effects of different progressive lenses and a single–vision lens on eye, head, and putter club movements during the golf putting stroke.
Methods: :
Six subjects, ranging in age from 49 to 69 years, participated in the study. Three lens conditions were tested: Single–Vision (SV), newer soft design (PAL1), and older hard design (PAL2) progressive lenses. The two progressive lenses have different intermediate zone widths (3.9 mm for the PAL1 and 2.3mm for the PAL2). For each condition, the subject completed 15 putts to a standard size golf–hole target 9 ft away. Eye, head, and putter movements were recorded at 3–sec intervals using a recently–developed wireless sensor system. The eye movements were recorded using the infrared limbus reflection technique, while the head and putter movements were recorded using onboard accelerometers. The eye and head signals were sent wirelessly to a PC via a circuit board mounted on a visor, while the putter signal was sent wirelessly via a circuit board mounted on the putter shaft. The data were analyzed over the interval from the beginning of the putt to the moment of ball impact. The root mean square (RMS) values of the eye, head, and putter signals within this time interval were calculated for each record, and the data were averaged across subjects. Putting accuracy was also monitored.
Results: :
The mean RMS values of the eye movements were not significantly different among the three conditions, although it was slightly smaller for the PAL2 condition. The mean head movement RMS values were not significantly different between the SV and PAL1 conditions, whereas it was significantly higher for the PAL2 than the PAL1 condition. In addition, putt amplitude, duration, and accuracy were not significantly different among the three conditions. There were no obvious differences between experienced and inexperienced golfers.
Conclusions: :
For the PAL2 condition, the larger head movements observed (and the corresponding smaller eye movement variation) may be due to its smaller intermediate zone width. Progressive addition lens users have been previously observed to remain well within the boundaries of the intermediate zone of clarity, possibly by adopting a conservative eye movement strategy, and therefore are forced to compensate with larger head movements. The results provide new and useful guidelines for the future design of progressive lenses to improve their performance during outdoor activities such as golf.
Keywords: ocular motor control • eye movements • vestibulo-ocular reflex