The symptomatic Pulfrich phenomenon can be successfully managed with a coloured lens in front of the good eye—a long-term follow-up study

Abstract

Purpose Many visual symptoms originating from a spontaneous Pulfrich phenomenon can be alleviated by the provision of a tinted lens worn in front of the least affected eye. Here, we report on the long-term outcome of four patients who have been provided with a uniocular tinted spectacle or contact lens. Methods The case notes of four cases were reviewed. The review period was at least 5 years in all four cases. Results In all cases, visual symptoms and perceptual difficulties occurring from the spontaneous Pulfrich effect were completely eliminated over a period of many years. In one case, the relief has been sustained over a 20-year period. Conclusions A uniocular tinted lens, or contact lens, provides immediate and lasting relief from the visual difficulties caused by the visual delay underlying the spontaneous Pulfrich effect.

The Pulfrich effect in the clinic

“…For instance, it has been found that the Pulfrich effect appears to distort velocity and size besides giving an illusion of depth [39]. Evidence that these perturbations in judgment of spatial dimensions and motion can be problematic in a variety of situations ( Table 2) comes from a number of case reports and retrospective studies [22,23,32,36,[40][41][42]. Judging the distance of objects and people when they are moving with respect to the observer can be difficult, while problems also exist for judging height, width and depth.…”

“…Problems with judging traffic impede driving [32], while being unable to judge motion accurately also affects performance in sports. Although some of these problems may seem mild, recognizing the symptoms of a spontaneous Pulfrich effect is important, as they may be potentially distressing and even dangerous, with the risk of road traffic accidents [36,43]. To investigate the influence of the Pulfrich effect on driving performance, Breyer et al [44] performed a three-dimensional computer driving simulation test on seven normal subjects, and found that the perturbation on vehicle position was greatest when the visual axis of the driver experiencing a Pulfrich effect was 90°to the direction of vehicle movement.…”

“…On top of a reduction in retinal illumination, it has been suggested that a unilateral cataract can also cause a spontaneous Pulfrich effect through retinal defocusing, i.e., blurring, which also slows retinocortical transmission and increases visual latency [23]. However, Cetinkaya et al [23,24] Corneal opacity [21] Iatrogenic, e.g., uniocular mydriasis, X-chrom lens [19] Traumatic anisocoria [21] Affecting neural conduction Post retinal detachment repair [21] Macular disease [26,27] Asymmetric pigmentary glaucoma [22] Central pathway conditions Optic neuritis/multiple sclerosis [21,[33][34][35][36][48][49][50] Mid-facial injuries [31,32] Other optic nerve pathologies [28][29][30]51] Pituitary tumours and temporoparietal astrocytomas [38] Anisometropic amblyopia [16] reported that the magnitude of the spontaneous Pulfrich effect in patients with unilateral cataracts did not correlate with visual acuity, but correlated with the presence of binocular symptoms [25]. Indeed, it has been suggested that the presence of the Pulfrich effect may account for visual symptoms in patients with unilateral cataracts that are independent of visual acuity, stereoacuity and contrast sensitivity [23].…”

“…Disorders affecting the retina, including central serous elevation of the macula [26], unilateral epiretinal membrane of the macula [27] and repaired retinal detachment [21], can delay conduction and have been reported to manifest a spontaneous Pulfrich effect associated with increased visual latency. Neural conduction can also be slowed in asymmetric optic nerve pathologies such as optic nerve hypoplasia [28], optic nerve head drusen [29], acute ischaemic optic neuropathy due to a presumed vascular accident [30], traumatic optic neuropathy due to mid-facial injury [31,32], and optic neuritis commonly associated with multiple sclerosis [21,[33][34][35][36].In patients with optic neuritis, the Pulfrich effect may account for difficulties with motion perception even in apparent recovery from optic neuritis, as it can be present due to residual optic nerve defects, and appears not to be related to the extent of acute visual loss and time elapsed since an attack of acute optic neuritis [34]. Interestingly, an asymptomatic inter-ocular signal latency difference in patients with multiple sclerosis can manifest as a spontaneous Pulfrich effect after exercise, presumably due to increased body temperature causing the Uthoff effect [37].…”

Pulfrich’s phenomenon in optic nerve hypoplasia

“…The need to position displays like the TV and blackboard to give a normal visual perspective in the absence of an ocular motility or orthopaedic disorder is odd, and seems beyond the usual array of problems we have encountered in cases of spontaneous Pulfrich effect [20]. A recent paper [21] has investigated the Pulfrich effect provoked in normals, using a driving simulator.…”