Influence of retinal vascular perfusion pressure on macular photostress recovery time

Maximal incremental exercise improves macular photostress recovery time and lowers intraocular pressure in healthy athletes

OBJECTIVES

Better visual performance in athletes compared to non-athletes could suggest improved macular function through physical exertion. The study aimed to investigate the effect of maximal incremental treadmill (MIT) exercise on macular function.

DESIGN

An interventional study comparing the effect of maximal incremental treadmill (MIT) exercise until volitional exhaustion between athletes (n = 26) and non-athletes (n = 26).

METHODS

Participants underwent an ophthalmological assessment involving repeated measurements of the photostress recovery time (PSRT) at baseline and post-exercise. PSRT was recorded after a 10-second exposure of the macular to an intense light source from an ophthalmoscope positioned 2 cm in front of the eye. Secondary outcome measures also recorded included the best-corrected visual acuity (BCVA) and the intraocular pressure (IOP).

RESULTS

Compared to the baseline, MIT exercise markedly improved the PSRT of athletes from 42.7 ± 1.6 s to 39.6 ± 1.4 s (P < 0.001), while having no significant changes in the PSRT of non-athletes. After adjusting for exercise duration, the exercise intervention showed significant effects on the PSRT improvement in the athletes compared to non-athletes after exercise [F(1,49) = 16.941, P < 0.001], with estimated marginal means of 3.00 s and 0.47 s, respectively. Also, the exercise intervention resulted in significant improvements in IOP (P < 0.001) and BCVA (P < 0.01) of both groups.

CONCLUSIONS

MIT exercise improves macular function, BCVA, and reduced IOP in healthy athletes. Maximal incremental exercise may be recommended for competitive sports athletes seeking optimal visual performance, as long as it does not adversely impact other relevant non-visual factors.

Using the POBF as an index of interocular blood flow effects during unilateral vascular stress

Kergoat and Lovasik [(1994). Ophthalmic and Physiological Optics, 14, pp. 401-407] reported that a transient decrease in ocular perfusion pressure (OPP) decreased the neural function in the test eye but increased the responsivity in the contralateral untouched (control) eye. Here the hypothesis tested was that a transient unilateral vascular stress would induce an increase in the Pulsatile Ocular Blood Flow (POBF) in the opposite eye. The POBF was measured in 20 healthy volunteers with normal intraocular pressure (IOP) and brachial blood pressure (BP). The OPP was decreased in the test (right) eye by scleral suction, and a Langham OBF system was used to make four readings of the POBF for each eye for baseline conditions, and when the OPP was decreased in the test eye alone by 20 and 40% for a 2 min period. Each individual, as well as the group averaged data showed a progressive decrease in the POBF in the test eye during a stepwise reduction in the OPP. No change was found for the POBF for the control eyes. Within the limitations of the systems and testing procedures employed, it is concluded that unilateral alterations in the OPP do not cause a change in the POBF in the contralateral eye.

Differential effects of compression and suction ophthalmodynamometry on the scotopic blue-flash electroretinogram

Several studies have investigated the effect of elevated intraocular pressure with reduced ocular perfusion pressure on visual neural function by means of compression and suction ophthalmodynamometry. We compared the effects of nominally equivalent reductions in the ocular perfusion pressure induced by compression and suction ophthalmodynamometry retinal function as measured by flash electroretinography. Scotopic blue-flash electroretinograms were recorded in five subjects for baseline conditions; during a 40% reduction in the ocular perfusion pressure effected in a first test session by compression ophthalmodynamometry; and then in a second test session some 4 hours later by suction ophthalmodynamometry. Fifteen consecutive electroretinographic sets were recorded during scleral compression or suction, and also after compression or suction was removed. Compression and suction ophthalmodynamometry decreased the electroretinogram b-wave to different degrees; overall, the electroretinogram was attenuated more by compression than by suction ophthalmodynamometry. In the recovery phase, the group averaged b-wave quickly increased to exceed baseline after both scleral compression and suction. The trends for prolonged implicit times over the duration of the study were similar for compression and suction ophthalmodynamometry.