Abstract
Purpose :
The diagnosis of internuclear ophthalmoplegia (INO) in multiple sclerosis (MS) can be easily missed in a clinical setting, therefore an accurate measurement with infrared oculography is essential. However, because no golden standard is available, it is difficult to compare different parameters quantifying the INO and finding the optimal threshold. The purpose of this prospective cohort study is to use Receiver Operator Curves (ROC) to compare existing parameters and a newly developed parameter for detecting INO and to describe visual complaints and functioning.
Methods :
A validated standardized infrared oculography protocol was used for quantifying pro-saccades in MS patients and healthy controls (HCs). The versional dysconjugacy index (VDI), describing the ratio between the abducting and adducting eye was calculated for peak velocity, peak acceleration and area under the curve of the saccadic trajectory (AUC). In order to compare sensitivity and specificity of the different VDI’s and different cut-off points, ROC analyses were performed with presence of MS as a surrogate outcome measure for presence of INO. Eye movement complaints and vision-related quality of life (VFQ-25 questionnaire) were compared between MS patients with and without an INO.
Results :
208 MS patients and 58 HCs were included. Given a (necessary) high specificity, the sensitivity was highest for the VDI AUC of 8 degrees saccades. With a VDI cut-off point of 1.26, 98% of HCs were correctly classified as not having INO, while 22% of MS patients were classified as INO. Of the 46 INO cases, 21 (46%) suffered from bilateral INO. In the INO group, 50% of patients had complaints with focusing on moving objects, compared to 38% of non-INO patients. Vision-related quality of life was lower in the INO group than in the non-INO group, most prominently in the subdomains distance activities (mean scores of 83 and 87 respectively, p=0.03) and mental health (means scores of 85 and 89 respectively, p=0.04).
Conclusions :
To our knowledge, this is the first systematic attempt to determine the optimal method for diagnosing (subclinical) INO with infrared oculography in a large clinical cohort. The newly developed parameter VDI AUC was found the best in discriminating INO from non-INO patients. Proper diagnosis can support in recognizing (misunderstood) visual complaints in patients and in selecting INO patients for future clinical trials.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.