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M.E. Reese, R.W. Hertle; Clinical Contrast Sensitivity (CS) Testing in Patients With Infantile Nystagmus Syndrome (INS) Compared to Age–Matched Controls . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2504.
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The purpose of this report is to characterize contrast sensitivity using a commercially available technique in those patients with the specific ocular motor disorder of INS.
This is a prospective, comparative case series between patients with INS and aged matched control children. The Functional Acuity Contrast Test (F.A.C.T.TM) was performed binocularly with best corrected acuity under normal office lighting (25–40 foot–Lamberts). The F.A.C.T.TM presents a progression of high–quality sine wave grating size changes with corresponding spatial frequencies of 1.5, 3, 6, 12, and 18 cycles per degree (cpd). The grating patch size is 1.7 degrees and the contrast step between each grating patch is 0.15 log units. The gratings are tilted +15o, 0o, and –15o and tapered into an average gray background to eliminate ghost images.
Nine INS patients aged 5–14 years and 25 controls aged 5–17 years were tested. The INS patients’ best binocular acuity ranged from 20/125 to 20/30, and the control subjects all had 20/25 or better binocular acuity. Other sensory system deficits in the INS population included optic nerve and foveal hypoplasia, and retinal dystrophy. F.A.C.T.TM testing in patients with INS showed a significant reduction of CS in the entire spatial frequency (1.5–18 cpd, p<0.05) range tested which was directly correlated to the INS patients best corrected acuity and was also significantly decreased compared to age matched controls.
The F.A.C.T.TM or a similar testing system may have potential as a commercially available clinical outcome measure in interventional trials in patients with INS.
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