J Korean Ophthalmol Soc.  2010 Jun;51(6):875-880. 10.3341/jkos.2010.51.6.875.

Relationship Between Visual Acuity and Foveation Window in Infantile Nystagmus by Analyzing Nystagmus Waveforms

• Chang JH
• Lee JB
• Kim SC
• Han SH

• KMID: 2213623
• DOI: http://doi.org/10.3341/jkos.2010.51.6.875

Abstract

PURPOSE
To report herein on Nystagmus Acuity Estimator Function (NAEF) based on the foveation time, obtained by analyzing waveforms of infantile nystagmus patients and comparing the results with the patients' actual visual acuity.
METHODS
Electro-oculographic data of 27 patients with infantile nystagmus were reviewed. Data of patients only with jerk type nystagmus and reliable visual acuity were analyzed. The foveation time was measured, and NAEF was calculated and compared with the patients' actual best corrected visual acuity.
RESULTS
A correlation analysis of the patients' best corrected visual acuity with NAEF was performed, and the retrieved coefficient was 0.4266. The p-value calculated using the Pearson correlation coefficient was 0.0282, implying that high NAEF correlates positively with visual acuity.
CONCLUSIONS
Estimated visual acuity, calculated based on the waveforms, positively correlates with the patients' actual visual acuity with statistical significance. However, since the foveation time can be measured only in the patients with jerk-type nystagmus waveforms, further study should be performed on the measurement of the foveation time with other waveforms. Furthermore, the present study shows that such analysis is possible with electrooculogram settings in most general hospitals.

Keyword

Foveation time; Infantile nystagmus; Nystagmus Acuity Estimator Function

MeSH Terms

Electrooculography
Hospitals, General
Humans
Visual Acuity

Figure

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  Figure 1. An eye tracing of a 42-year-old male diagnosed with infantile nystagmus shown with our program. Upper graph (Ch A) shows eye positional tracing and lower graph (Ch B) shows eye velocity tracing. Upward deflection denotes rightward direction. First, using cursors (red cross and yellow cross shown on the graph), we identified the interval of ±4°/sec velocity. Second, we check the chosen velocity interval meets the ±0.5° positional criterion. If the interval meets two criteria, we calculate foveation time (Tf) and standard deviation of position (SDp). For de-tails, see the text.

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  Figure 2. Relationship between NAEF and best corrected visual acuity (BCVA) (correlation coefficient=0.4266. Pearson correlation coefficients: p-value=0.0282) Horizontal axis denotes BCVA (best corrected visual acuity of patients); vertical axis denotes NAEF (nystagmus acuity estimator function of patients).

Reference

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