Exercise Does Not Increase Visual Field Sensitivity

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/15312900

Exercise Does Not Increase Visual Field Sensitivity Article in Optometry and Vision Science · December 1994 DOI: 10.1097/00006324-199411000-00002 · Source: PubMed

CITATIONS

READS

11

19

3 authors, including: Russell Laurence Woods Schepens Eye Research Institute 118 PUBLICATIONS 1,671 CITATIONS SEE PROFILE

All content following this page was uploaded by Russell Laurence Woods on 26 December 2016. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.

1040-5488/94/7111-0682$03.00/0 OPTOMETRY AND VISION SCIENCE Copyright©1994 AMERICAN ACADEMY OF OPTOMETRY

* Centre for Eye Research, Sch

Vol. 71, No. 11, pp. 682-684

* an

The effect of exercise on visual field sensitivity was investigated for both static using the Humphrey Field A ser (~~A)” The wisual fields of 20 young visually normal subjects were measured before and after a $O-min ontroll~d period of exercise. Ten of these 20 subjects then formed a control group, where the same experimental regime was followed without the exercise period. A significant increase in mean static sensitivity in the superior field was found as a result of exercise; however, this is likely to be a learning effect as a similar increase was also found for the control condition. ercise had no other effect on either the kinetic or atic visual fields. Key Words: visual fields, physical exercise

Previous studies suggested that exercise can increase a num f visual functions including kinetic’s 2 and static3 visual fields. Conversely, Jones and Wilcott4 reported decreased night vision in the inferior hemifield after exercise. Jones and Wilcott’ attributed this to the decrease in ophthalmic arterial pressure observed in exercising individuals, plus changesin cerebral autore~lation in extreme exercise, which they suggest may result in a relative paucity of blood in the upper portions of the retina and, hence, reduced sensitivity in the inferior field. Whether these changes in field sensitivity from exercise arise from hormonal changes (i.e., endomorphins) or underlying physiological changes (such as increased retinal perfusion) remains unclear. Furthermore, the experimental design of these studies failed to include any control groups, thus it was not possible to determine whether any improvements in the visual field arose as a result of placebo or learning effects. This lack of control groups is important as improvements in visual field sensitivity at peripheral locations, particularly in the superior hemifield, have been reported with practice.5 We measured visual field sensitivity before and after exercise using kinetic and static techniques. ~-~. _~.___._~-Received March 8, 1994; revision received August 22, 1994. * Optometrist, Ph.D., Member of Faculty. § Optometrist, B Appl SC.

682

OPTOVIETRY & ViSiON SCIENCE

§

d University of Technology, Brisbane, Australia

This was repeated using a control group to determine whether any improvements-in sensitivity arose simply from learning effects or from underlying physiological changes.

volunteers aged between 20 and 29 years (mean 24.0 years; SD 3.6 years) who participated in the study after written informed consent had been obtained. Al1 subjects were in good general health, and were free of any ocular> neurological, or systemic disease with known ophthalmic complications. All subjects had corrected monocular visual acuities of 6/6 or better. Subjects were required to attend two sessions on separate days, the first being a practice session to familiarize each subject with the visual field procedures. At the second session, kinetic and static visual fields were measured before and after a period of controlled exercise. Measurement was made while the subject was seated on the exercise bicycle. xet-cise

Blood pressure and pulse rate were measured using an electronic sphy~omanometer before and 5 to 7 min after the exercise period. Subjects pedalled for 10 min on a Cateye Ergociser EC 1000 exercise bike (at a cadence of 80 to 90 rev/ min), during which the workload intensity was adjusted so that they were within the optimal aerobic training zone for their age. This was Calculated by taking 75% of their maximal heart rate (220 minus the subject’s age). Pulse rate was monitored with a pulse meter attached to the ear lobe and monitored at 30-s intervals during the exercise and postexercise testing.

Measures of both static and kinetic visual fields were performed while the subject was seated on the exercise bicycle in front of the Humphrey Field Analyser (HFA) with the room lights extinguished. The height of the exercise bicycle was adjusted to ensure that subjects were able to place their chin comfortably on the perimeter chin rest. Lateral alignment of the chin rest was made using the eye monitor of the HFA as a guide to

position the pupil center at the fixation cross. All visual field testing was undertaken monocularly for the right eye with the left eye occluded. Static visual field sensitivity was measured at nine points across the visual field (illustrated in Fig. 1) for target size III using a customized Fastpat program. Subjects were instructed to fixate the central spot (or the center of the four fixation lights for fovea1 thresholds) and respond to presentation of the perimetric targets by pressing the button. Fixation was closely monitored to ensure that changes in position on the exercise bicycle did not alter head position. Test duration was approximately 3 min. Results were calculated as a function of each of the nine locations and as a mean value for the superior and inferior hemifields. Kinetic visual fields were measured on the HFA using target 1114e along the 15’, 45’, 75’, 105’, 135O, 165’, 195’, 225’, 25Y, 285O, 315’, and 345’ meridians. Test duration was approximately 3 min. The extent of the field along each of the measured meridians was determined by taking the eccentricity at which the target was first seen, Data were also analyzed for each field by calculating the area enclosed by the isopter using a custom written computer program. The order of visual field tests was randomized for each subject and the procedures were repeated immediately before and after the exercise period.

Ten of the original 20 subjects aged between 20 and 29 years (mean 25.2 years; SD 4.0 years) also participated as the control group. The procedures were identical to those used for the first part of the study, except that subjects did not undergo a period of exercise but were given a lO”min rest period in which no strenuous activity was undertaken.

roup means for pre- and postexercise and preand postrest measures given in Tables 1 and 2 for the kinetic and static measures, respectively, were analyzed for a difference using a 2-way repeated measures analysis of variance.

UeQc Fields. No differences in kinetic isopter area or field extent along the 12 meridians were found between the pre- and postexercise measures. Static Fields, No difference in static visual field sensitivity was found between the pre- and postexercise measures, although there was a significant interaction between session and visual field location Cdf 8,152; F 3.5; p = 0.001). This interaction was confirmed by post hoc analysis using the paired Student’s t-test, which indicated that these increases were at the upper locations in the visual field at x,y coordinates (-30,301 and (30,301 (see Fig. 1). When the visual field was considered as upper and lower hemifields, there was an interaction between visual hemifield and session Cdf 1,19; F 5.7; p = 0.03). This interaction was the result of an increase in sensitivity after exercise in the upper hemifield but not in the lower hemifield. No change in fixation losses or false negative and false positive responses was found between the pre- and postexercise measures.

Kirtetic Fields. No significant differences in isopter area or field extent along the 12 meridians were found for the pre- and postrest measures. Static Fields. A significant increase in visual field sensitivity was found between the pre- and postrest measures (df 1,9; F 6.3; p = 0.03) and there was no interaction effect. Further analysis using the paired Student’s t-test revealed a significant increase in sensitivity only in the superior nasal quadrant at x,y coordinates (-551 (see TABLE I. Group mean kinetic visual field extent along the 12 tested meridians for the pre- and postexercise and pre- and postrest testing conditions.a

Testing Conditions _~._.. M e r i d i a n ~-Exercise N = 20 Rest N = IO (7 ~__ ~__ PrePostPrePost-

ig. I. Schematic representation of the field locations (“) tested for measurement of static visual field sensitivity.

15 45 75 105 135 165 195 225 255 285 315 345

58.8 (8.1) 42.1 (9.7) 34.0 (6.6) 34.4 (5.9) 40.1 (7.6) 44.5 (4.8) 44.8 (5.7) 40.2 (4.7) 38.7 (4.0) 43.0 (3.8) 52.5 (4.7) 63.6 (6.2)

58.2 (8.9) 43.6 (7.8) 32.6 (9.0) 33.1 (7.4) 37.7 (5.4) 43.5 (5.3) 42.1 (4.8) 38.9 (3.9) 38.0 (6.0) 43.8 (4.5) 52.3 (4.8) 63.3 (6.6)

60.9 (4.5) 50.4 (5.2) 38.6 (4.3) 39.5 (4.3) 49.2 (3.9) 64.6 (5.0) 66.1 (4.9) 55.6 (3.3) 46.0 (4.1) 45.7 (3.9) 55.4 (2.9) 66.7 (2.5)

61.2 (5.8) 48.9 (6.6) 38.9 (4.3) 38.7 (5.0) 48.9 (4.6) 62.3 (6.9) 65.4 (6.4) 53.8 (4.4) 46.1 (3.4) 44.9 (3.9) 55.5 (2.7) 65.2 (4.2)

a SD's are given in parentheses. Effect of Exercise on Field Sensitivity-Wood et al.

683

T ABLE 2. Group mean static visual field sensitivity at the 9

tested locations for the pre- and postexercise and pre- and postrest testing conditions.a EccenVicity (X, Y values)

Y)

{EYE; (51-5) :%5’ (30,iO) (30,-30) (-30,-30) (-30,30)

~.__

.-

Testing Conditions

Exercise N = 20

Pre-

37.7 32.8 33.5 33.5 33.0 23.9 28.2 24.0 19.8

Post-

Rest N = IO _---.---Pre-

Post-

(1.9) 37.3 (2.1) 39.1 (1.9) 39.0 (2.5) (1.7) 32.8(1.8) 35.1 (1.6) 35.1 (1.2) (1.3) 32.9 (2.1) 35.7 (1.3) 36.3 (1.5) (1.5) 32.8 (1.7) 35.8 (1.2) 35.8 (1.2) (2.1) 33.2 (1.3) 34.8 (1.1) 36.4 (1.3) (3.8) 25.7 (4.2) 26.3 (3.6) 27.3 (2.7) (1.7) 28.7 (1.7) 29.1 (2.2) 30.0 (1.7) (2.4) 23.1 (6.1) 28.7 (1.7) 29.6 (1.4) (8.4) 23.3 (7.0) 27.3 (3.7) 28.7 (1.7)

ZI SD’s given in parentheses.

1). When the visual field was considered as upper and lower hemifields, there was no interaction between visual hemifield and se&ion, there being an increase in sensitivity after rest in both the upper and lower hemifields. No change in fixation losses or false negative and false positive responses was found between the pre- and postrest measures. F’ig.

ISCUSSICN Exercise did not have any significant effect on either kinetic or static measures of the visual field, over and above those found for the control condition. An improvement in visual field sensitivity in the superior hemifield was found for both the exercise and control conditions and is likely to be a result of practice or learning effects as previously reported by Wood et aL5 Static visual field sensitivity also increased in the inferior hemifield for the rest condition but not after exercise, indicating that exercise may effectively reduce sensitivity in the inferior hemifield, in accord with the findings of Jones andWilcott.4 The lack of change in criterion indicators such as false negative and positive responses between sessions indicates that any differences in sensitivity found in this study are unlikely to have arisen from changes in decision criteria. Our finding that exercise had no effect on either kinetic or static visual fields differs from those of previous studies,lm3 and from less recent studies cited in the sports vision literature; for example, Purvis.6 This lack ,of agreement may be explained in terms of differences in visual field techniques, sample size, and lack of control groups in the earlier studies. In the studies of Blundell’ and Fleury and Bard’ and in the many unpublished studies cited in the sports vision literature, manual perimetric techniques have been used. Such techniques may introduce experimenter biases as well as providing only quali.tative data regarding the extent of the visual field. An automated perimeter was 684

View publication stats

OPTOMETRY & VISION SCIENCE

used in our study in order to avoid bias and to give numerical data which could be analyzed quantitatively. Koskela et al.3 reported improvements in the mean deviation index of visual fields measured using the HFA for one subject after jogging, although data on false positive and false negative indices were not given. Testing of only one subject severely limits the usefulness of such a study, particularly given the wide variation in visual field sensitivity reported in this study and the individuality of visual responses to exercise.7 Twenty subjects were included in our study, which we believe is the minimum number of subjects needed to provide an adequate representation of these effects. Failure to include adequate control groups is a problem common to all the previous studies which have investigated the effect of exercise on the visual fields. Thus any cited improvements in sensitivity cannot be attributed to any physiological effects associated with exercise, unless the well-known practice and placebo effects have been accounted for. The results of this study indicate that visual fields do not improve after exercise over and above the effects of learning. This in accord with the study of Woods et al.,8 who found that exercise also did not have any effect on contrast sensitivity when an adaptive psychometric measurement procedure was used. Together, these studies show that previous studies are likely to have inappropriately attributed improvements in sensitivity arising from learning effects, shifts in decision criteria, or examiner bias to exercise-induced changes. REFERENCES 1

Blundell NL. The contribution of vision to the learning and performance of sports skills: Part 2: The effects of exercise, altitude and visual training. Aust J Sci Med & Spt 1985;17: 3-7. Fleury M, Bard C. Fatigue metabolique et performance de taches visuelles. Can J Spt Sci 1990;15:43-50. Koskela PU, Airaksinen PJ, Tuulonen A. The effect of jogging on visual iield indices. Acta Ophthalmol (Kbh) 1990;68:91-3. Jones RK, Wilcott IT, Topographic impairment of night vision related to exercise. Am J Ophthalmol 1977;84:868-71. Wood JM, Wild JM, Hussey MK, Crews SJ. Serial examination of the normal visual field using Octopus automated projection perimetry: evidence for a learning effect. Acta Ophthalmol (Kbh) 1987;65:326-33. 6. Purvis GJ. The effects of three levels of duration and intensity of exercise upon the peripheral vision and depth perception of women. Unpublished Ph.D. dissertation. Louisiana State University 1973. Cited by: Blundell NL (1985). 7. Koskela PU. Jogging and contrast sensitivity. Acta Ophthalmol (Kbh) 1988:66:725-7. 8. Woods RL, Wood JM, Jack MP, Exercise does not increase contrast sensitivity. Optom Vis Sci, submitted. AU-l’HOR’S ADDRESS: Joanne M. Wood Centre for Eye Research Queensland University of Technology Locked Bag 2, Red Hi//, Brisbane Q4058 Australia