scholarly journals The effect of refractive error on optokinetic nystagmus

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Soheil M. Doustkouhi ◽  
Philip R. K. Turnbull ◽  
Steven C. Dakin
Keyword(s):  
Eye Movement ◽  
Refractive Error ◽  
Optokinetic Nystagmus ◽  
Contact Lenses ◽  
Objective Measure ◽  
Mean Difference ◽  
Movement Velocity ◽  
Patient Response ◽  
Stimulus Velocity ◽  
Filtered Noise

AbstractSubjective refraction is the gold-standard for prescribing refractive correction, but its accuracy is limited by patient’s subjective judgment about their clarity of vision. We asked if an involuntary eye movement, optokinetic nystagmus (OKN), could serve as an objective measure of visual-clarity, specifically measuring the dependence of OKN—elicited by drifting spatial-frequency filtered noise—on mean spherical equivalent (MSE) refractive error. In Experiment 1 we quantified OKN score—a measure of consistency with stimulus-direction—for participants with different MSEs. Estimates of MSE based on OKN scores correlate well with estimates of MSE made using autorefraction (r = 0.878, p < 0.001, Bland–Altman analysis: mean difference of 0.00D (95% limits of agreement: − 0.85 to + 0.85D). In Experiment 2, we quantified the relationship between OKN gain (ratio of tracking eye-movement velocity to stimulus velocity) and MSEs (− 2.00, − 1.00, − 0.50, 0.00 and + 1.00D) induced with contact lenses for each participant. The mean difference between measures of MSE based on autorefraction or on OKN gain was + 0.05D (− 0.90 to + 1.01D), and the correlation of these measures across participants was r = 0.976, p < 0.001. Results indicate that MSE attenuates OKN gain so that OKN can be used as an objective proxy for patient response to select the best corrective lens.

Eye movement abnormalities in somatic tinnitus: Fixation, smooth pursuit and optokinetic nystagmus

2010 ◽  
Vol 37 (3) ◽  
pp. 314-321 ◽  
Author(s):  
Z. Kapoula ◽  
Q. Yang ◽  
M. Vernet ◽  
P. Bonfils ◽  
A. Londero
Keyword(s):  
Eye Movement ◽  
Smooth Pursuit ◽  
Optokinetic Nystagmus

scholarly journals The impact of wearing single vision soft contact lenses on the peripheral refractive error

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 2803
Author(s):  
Kareem Allinjawi ◽  
Sharanjeet-Kaur Sharanjeet-Kaur ◽  
Saadah Mohamed Akhir ◽  
Haliza Abdul Mutalib
Keyword(s):  
Visual Field ◽  
Open Field ◽  
Refractive Error ◽  
Contact Lens ◽  
Contact Lenses ◽  
Soft Contact ◽  
Soft Contact Lenses ◽  
Single Vision ◽  
The Right ◽  
The Impact

Aim: The purpose of this study was to determine the changes in the relative peripheral refractive error produced by soft single vision contact lenses in myopic schoolchildren. Methods: 27 myopic schoolchildren aged between 13 to 15 years were included in this study. The measurements of central and peripheral refraction were made only on the right eye using a Grand-Seiko WR-5100K open-field autorefractometer without contact lens (WL), and with wearing single vision contact lens (SVCL). Refractive power was measured at center and horizontal eccentricity between 35° temporal to 35° nasal visual field (in 5° steps). Results: SVCL showed an increase in peripheral hyperopic defocus at the nasal and temporal visual field compare with baseline, but this change was not statistically significant (p=0.129). Conclusion: Wearing single vision soft contact lenses increases the relative peripheral hyperopic defocus in myopic schoolchildren.

Prevalence and Determining Factors Of Refractive Errors Among Medical Students In FMU, Faisalabad

2021 ◽  
Vol 15 (11) ◽  
pp. 2934-2935
Author(s):  
Nadia Tufail ◽  
Huda Abbas ◽  
Ali Sarfraz ◽  
Sumaira Ashraf ◽  
M. Ashraf Majrooh
Keyword(s):  
Medical Students ◽  
Mobile Phone ◽  
Mobile Phones ◽  
Refractive Error ◽  
Contact Lenses ◽  
Electronic Devices ◽  
Quantitative Information ◽  
Refractive Errors ◽  
Cross Sectional ◽  
Determining Factors

Aim: Prevalence and determining factors of refractive errors among the medical students in FMU, Faisalabad. Methodology: Cross-sectional quantitative study conducted in Faisalabad Medical University from 01-03-2020 to 15-12-2020 after approval from institutional review committee. All students of MBBS in FMU were included in this study. A structured questionnaire was used to collect the required quantitative information. SPSS version 26 was used for analysis. Results: Prevalence of refractive error is 49%. Females were 59% and males were 41%. More students i.e. 85.2% were suffering from myopia. In our study, usage of electronic devices i.e. mobile phones especially was one of the risk factors in developing refractive errors. 20.6% students having refractive error said that they use mobile phone for 4 hours, 30.2% having refractive error said that they watch TV for one hour, 23.3% having refractive error said that they play video games for one hour. For the correction of the refractive error, 184 students i.e. 97.4% used spectacles whereas only 5 (2.6%) students used contact lenses. It is observed in this study that contact lenses were only used by those students having refractive error <1.5. Conclusion: Refractive errors were a significant cause of visual impairment among medical students. The prolonged use of electronic devices especially mobile phones should be discouraged. Keywords: Refractive errors, myopia, electronic devices, mobile phone

Establishing an Objective Measurement of Visual Acuity with a Computerised Optokinetic Nystagmus Suppression Test

2020 ◽  
Vol 237 (04) ◽  
pp. 502-505
Author(s):  
Noemie Schwob ◽  
Anja Palmowski-Wolfe
Keyword(s):  
Visual Acuity ◽  
Eye Movements ◽  
Optokinetic Nystagmus ◽  
Objective Measurement ◽  
Mean Difference ◽  
Alternative Option ◽  
Snellen Acuity ◽  
Suppression Test ◽  
Infrared Cameras ◽  
Acuity Test

Abstract Objective Investigating the correlation between subjective and objective VA (visual acuity) elicited with a newly developed computerised optokinetic nystagmus (OKN) suppression test (“SpeedWheel”) in adults. Methods SpeedWheel presented alternating black/white stripes moving horizontally across a LED screen. Seven VA steps were induced with Bangerter filters placed onto spectacle frames. Magnified eye movements were projected from infrared cameras inside the frames and displayed onto a smartphone. Dots whose size increased in logarithmic steps were superimposed to suppress OKN. Suppression of OKN resulted in the SpeedWheel acuity which was then correlated to Snellen acuity as measured with the Freiburg Acuity test. Results 28 eyes from 14 individuals were tested. FrACT-E correlated well to SpeedWheel (r: 0.89; p < 0.001). Snellen acuity was never lower than 0.14 LogMAR of SpeedWheel values. Bangerter filters showed greater mean difference to both methods indicating that this filter is not as predictable as suggested by the filter value. Conclusion SpeedWheel offers a fast (< 80 sec) and reliable alternative option to measure objective VA.

Fatigue-induced Impairments In Eye-movement Velocity Are Reversed By Caffeine

2014 ◽  
Vol 46 ◽  
pp. 740
Author(s):  
Charlotte J. w. Connell ◽  
Benjamin Thompson ◽  
Shelley Duncan ◽  
Michael P. Claffey ◽  
Gustav Khun ◽  
...  
Keyword(s):  
Eye Movement ◽  
Movement Velocity

Eye Movements in Cerebellar and Combined Cerebellobrainstem Diseases

1983 ◽  
Vol 92 (2) ◽  
pp. 165-171 ◽  
Author(s):  
Carsten Wennmo ◽  
Bengt Hindfelt ◽  
Ilmari Pyykkö
Keyword(s):  
Quantitative Analysis ◽  
Eye Movements ◽  
Eye Movement ◽  
Smooth Pursuit ◽  
Optokinetic Nystagmus ◽  
Vestibular Nystagmus ◽  
Full Field ◽  
Eye Velocity ◽  
Voluntary Saccades ◽  
Cerebellar Disorders

We report a quantitative analysis of eye movement disturbances in patients with isolated cerebellar disorders and patients with cerebellar disorders and concomitant brainstem involvement. The most characteristic abnormalities in the exclusively cerebellar patients were increased velocities of the slow phases of vestibular nystagmus induced by rotation in the dark and increased peak velocities of the fast phases of optokinetic nystagmus induced by full-field optokinetic stimuli. Dysmetria of saccades was found in three of six cerebellar patients and gaze nystagmus in all six patients. The typical findings in the combined cerebellobrainstem group were reduced peak velocities of voluntary saccades, defective smooth pursuit and reduced peak velocities of the fast component of nystagmus during rotation in both the dark and light. All patients with combined cerebellobrainstem disorder had dysmetric voluntary saccades and gaze nystagmus. The numbers of superimposed saccades during smooth pursuit were uniformly increased. Release of inhibition in cerebellar disorders may explain the hyperresponsiveness and inaccuracy of eye movements found in this study. In addition, when lesions also involve the brainstem, however, integrative centers coding eye velocity are affected, leading to slow and inaccurate eye movements. These features elicited clinically may be useful in the diagnosis of cerebellar and brainstem disorders.

Determination of smooth pursuit eye movement velocity in humans by computer

1982 ◽  
Vol 54 (4) ◽  
pp. 399-405 ◽  
Author(s):  
P.R.M Bittencourt ◽  
A.T Smith ◽  
D.S.L Lloyd ◽  
A Richens
Keyword(s):  
Eye Movement ◽  
Smooth Pursuit ◽  
Movement Velocity ◽  
Smooth Pursuit Eye Movement
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