Ocular Tremor in Parkinson’s Disease: Discussion, Debate, and Controversy

Abstract

The identification of ocular tremor in a small cohort of patients with Parkinson’s disease (PD) had lay somewhat dormant until the recent report of a pervasive ocular tremor as a universal finding in a large PD cohort that was, however, generally absent from a cohort of age-matched healthy subjects. The reported tremor had frequency characteristics similar to those of PD limb tremor, but the amplitude and frequency of the tremor did not correlate with clinical tremor ratings. Much controversy ensued as to the origin of such a tremor, and specifically as to whether a pervasive ocular tremor was a fundamental feature of PD, or rather a compensatory eye oscillation secondary to a transmitted head tremor, and thus a measure of a normal vestibulo-ocular reflex. In this mini review, we summarize some of the evidence for and against the case for a pervasive ocular tremor in PD and suggest future experiments that may help resolve these conflicting opinions.

Eye movement evaluation in Multiple Sclerosis and Parkinson’s Disease using a Standardized Oculomotor and Neuro-ophthalmic Disorder Assessment (SONDA)

“…Another example of the use of eye-movement-based metrics is the assessment of surgical or pharmacological interventions for nystagmus (Hertle et al, 2003; McLean et al, 2007). Such disorders are rather common in MS when lesions involve the brainstem and the cerebellum (Elliot M. Frohman et al, 2005) and can occur in PD as well, sometimes causing oscillopsia (Kaski & Bronstein, 2017).…”

The First Evidence on the Occurrence of Bisphenol Analogues in the Aqueous Humor of Patients Undergoing Cataract Surgery

“…Demonstrating the presence of BPA in AH seems to be important from the point of view of many potential threats related to BPs intoxication starting from direct oxidative damage [ 81 ], changing the activity of many enzymes [ 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 ], deregulation of the gene expression [ 55 , 92 ], up to the increase in pro-inflammatory cytokines [ 93 ], and apoptotic proteins [ 94 ].…”

“…NO is a key molecule that has the ability to dilate blood vessels and regulate microcirculation. Decreased NOS expression has been associated with the development of hypertensive retinopathy, cataracts, glaucoma, vitreous hemorrhage [ 86 ], and the cell proliferation (hyperplasia) of ocular cancer and degeneration of retinocyte outgrowth, with the deterioration of conjunctiva and lens [ 87 ]. Another enzyme that is associated with BPA intoxication is arginase, the increased expression of which can trigger inflammatory processes [ 88 ] that lead to the development of cataracts.…”

Eye Movement Evaluation in Multiple Sclerosis and Parkinson's Disease Using a Standardized Oculomotor and Neuro-Ophthalmic Disorder Assessment (SONDA)

“…Another example of the use of eye-movement-based metrics is the assessment of surgical or pharmacological interventions for nystagmus ( 45 , 46 ). Such disorders are rather common in MS when lesions involve the brainstem and the cerebellum ( 2 ) and can occur in PD as well, sometimes causing oscillopsia ( 47 ).…”