Medication adversely impacts visually-guided eye movements in Parkinson’s disease

Medication only improves limb movements while deep brain stimulation improves eye and limb movements during visually-guided reaching in Parkinson’s disease

“…The results from separate eye only and upper limb only movement tasks suggest that antiparkinson medication may have differential effects on the eyes and upper limbs. We have recently shown that medication increased saccade latency ( Munoz et al, 2022 ), confirming the findings of previous studies ( Müller et al, 1994 ; Michell et al, 2006 ; Hood et al, 2007 ; Dec-Ćwiek et al, 2017 ; Lu et al, 2019 ; Waldthaler et al, 2019 ). However, other studies have reported that medication does not have a significant effect on saccade latency ( Gibson et al, 1987 ; Rascol et al, 1989 ; Temel et al, 2009 ; van Stockum et al, 2012 ; Cubizolle et al, 2014 ; Bakhtiari et al, 2020 ), which could be due to suboptimal medication doses ( Munoz et al, 2022 ).…”

“…The third study did not show a slight decrease, possibly because of the small medication dosage given to the participants ( Rascol et al, 1989 ). Our recent study found a statistically significant decrease in peak velocity with medication on the visually-guided saccade task ( Munoz et al, 2022 ). In the present study, we extended previous saccade findings.…”

“…During the visually-guided saccade task, medication typically decreased saccade peak velocity, either significantly ( Munoz et al, 2022 ) or not significantly ( Dec-Ćwiek et al, 2017 ; Lu et al, 2019 ). Conversely, studies reported that medication typically increased the peak velocity of simple upper limb movements during reach-to-grasp tasks ( Castiello et al, 2000 ; Negrotti et al, 2005 ; Schettino et al, 2006 ), arm abduction to match a target ( Baroni et al, 1984 ), wrist flexion ( Berardelli et al, 1986 ; Johnson et al, 1994 ), elbow flexion ( Robichaud et al, 2002 ; Vaillancourt et al, 2004 ), and reach- or point-to-target tasks ( Kelly et al, 2002 ; Camarda et al, 2005 ).…”

“…We have recently shown that medication increased saccade latency (Munoz et al, 2022), confirming the findings of previous studies (Müller et al, 1994;Michell et al, 2006;Hood et al, 2007;Dec-Ćwiek et al, 2017;Lu et al, 2019;Waldthaler et al, 2019). However, other studies have reported that medication does not have a significant effect on saccade latency (Gibson et al, 1987;Rascol et al, 1989;Temel et al, 2009;van Stockum et al, 2012;Cubizolle et al, 2014;Bakhtiari et al, 2020), which could be due to suboptimal medication doses (Munoz et al, 2022). Conversely, the medication effect on simple RT tasks evaluating upper limb movement has typically lacked statistical significance, however, there has been a consistent pattern of medication decreasing simple RT within all (Velasco and Velasco, 1973;Bloxham et al, 1987;Pullman et al, 1988Pullman et al, , 1990Starkstein et al, 1989;Jahanshahi et al, 1992;Fern-Pollak et al, 2004;Ingram et al, 2021) but one study (Müller and Harati, 2020).…”

Oculometric measures as a tool for assessment of clinical symptoms and severity of Parkinson’s disease

“…First, this is a cross-sectional study, therefore its design does not necessarily reflect the potential changes in patients’ condition over time. Another limitation relates to exploring the effect of medication dosage on OM, which has mixed results in the literature (Waldthaler et al 2019 ; Lu et al 2019 ; Munoz et al 2022 ). When comparing patients with and without levodopa treatment, matched for their MDS-UPDRS scores, we found that some OM (pro-saccade latency and error rate) were different, however we did not further analyze the potential reasons for these differences, especially the potential effect of other medications and the possible bias that patients under levodopa were in a more advance stage of the disease.…”