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Christina M. Ohnsman, Yevgeniya Atiskova, Jan Wildner, Boaz Konig, Angela Schulz, Simon Dulz; Pilot Study of Novel Optokinetic Nystagmus-Based Visual Acuity Test in Children with CLN2 Disease. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3141.
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© ARVO (1962-2015); The Authors (2016-present)
Vision loss is a prominent feature of neuronal ceroid lipofuscinosis Type 2 (CLN2) Batten disease, developing after cognitive, motor and language impairments are already present. While progressive, symmetrical loss of central retinal thickness (CRT) has been well characterized in CLN2 disease, measurement of visual acuity (VA) using standard methods is difficult and unreliable in this population, resulting in lack of natural history data on the range, severity and impact of visual impairment. We conducted a pilot study of a novel VA test using optokinetic nystagmus (OKN) detection technology (Threshold Visual Acuity Test, Objective Acuity, Ltd., Auckland, NZ) to determine its usefulness in children with CLN2 disease.
23 children ages 3 to 9 with classic CLN2 disease followed at University Medical Center Hamburg-Eppendorf (UKE) were included. Binocular and monocular VA testing using Threshold Visual Acuity Test and binocular VA testing using preferential looking (PL) were performed at two consecutive visits two weeks apart. CRT was measured under anesthesia using SD-OCT. VA testing results were correlated with CRT.
Seventeen children (74%) tested with the Threshold Visual Acuity Test had measurable binocular VA, while 6 (26%) had no detectable OKN, indicating VA>1.3 logMAR. Binocular VA ranged from 0.3 to >1.3 logMAR and was strongly correlated with CRT (R= -0.93; Figure 1). Eighteen children (78%) had measurable VA with PL and 5 (22%) were unresponsive. VA measured by PL was poorly correlated with CRT (R= -0.44). Monocular VA measured by OKN was obtained in 12 right eyes and 11 left eyes; 9 children cooperated with monocular testing in both eyes. Monocular VA was highly symmetric between right and left eyes (R=0.95) and correlated with CRT (R= -0.84 OD; R= -0.88 OS).
The novel, OKN detection-based Threshold Visual Acuity Test appears to be useful in children with CLN2 disease. Results demonstrate the high correlation between CRT and VA as well as symmetrical VA between eyes in this population. More longitudinal data are needed to characterize the pattern and progression of VA loss in CLN2 disease. Additional validation studies with an expanded range of VA are underway.
This is a 2021 ARVO Annual Meeting abstract.
Figure 1. Relationship between CRT and binocular VA in CLN2 disease
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