# User Friendliness of a Wearable Visual Behavior Monitor for Cataract and Refractive Surgery
###### Abstract  
A prospective feasibility study was conducted to determine whether a new wearable device, the Visual Behavior Monitor (VBM), was easy to use and did not present any difficulties with the daily activities of patients. Patients for cataract surgery and refractive lens exchange were randomly selected and screened for inclusion in the study. A total of 129 patients were included in the study as part of a multicenter study. All measurements were performed before surgery. Upon inclusion, patients were trained to wear the device, instructed to wear it for a minimum of 36 h, and were scheduled to return in one week. The VBM measures the distance at which patients' visual activities are performed, the level of illumination, and head translational and rotational movements along the three axes. On the follow-up visit, patients completed a questionnaire about their experience in wearing the device. All patients underwent standard diagnostic testing, with their cataract grade determined by the Lens Opacities Classification System (LOCS) classification. Results indicate that 87% of patients felt comfortable using the wearable device while 8% of patients responded as not feeling comfortable (5% of patients did not respond to the question). In addition, 91% of patients found it easy to attach the wearable to the magnetic clip while 4% of patients did not find it easy, and 5% of patients did not respond. Overall, patients found the device easy to use, with most reporting that the device was not intrusive. cataract surgery; refractive surgery; visual behavior monitor +
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Approaching the intended post-operative spherical equivalent, however, often does not achieve spectacle independence. Uncorrected residual spherocylindrical refractive errors appear to have far greater adverse effects on unaided visual acuity than may be evident using a spherical equivalent or the individual sphere and cylinder. If the correction of presbyopia is desired, there are three options available for IOLs in the course of cataract surgery. One is the installation of a monovision where the dominant eye is set for distance and the non-dominant eye for near. A difference of up to 2 D is accepted by the patient. However, before proceeding to surgery, it is essential to try wearing contact lenses to see if the correction is tolerated [4; 5]. Most patients reported the surgery met their expectations for decreased dependence on spectacles (93%) [6]. The extended-depth-of-focus-IOL (EDOF-IOL) provides an extended depth-of-field range. Actually, it is a bifocal IOL with a low near-addition of 1.5-2.0 D. This results in excellent distance and intermediate correction without the disadvantages of a multifocal IOL. However, this procedure does not completely eliminate the need for spectacles [5; 7]. The third possibility of correction is the implantation of a trifocal IOL. One is located in the distance and receives 50% of the incident light, the second is at 30-40 cm and receives 30% of the light, and the third is at about 60 cm and receives 20% of the light. The strength of trifocal IOLs is that they are glasses-free. The weakness is that fixed distances are given, which requires some getting used to, and that the intermediate part is the weakest. As only a part of the light used for image generation is sharp, there is a loss of contrast, which is noticeable. In addition, undesirable optical side effects in the form of so-called halos or glare occur, which impair vision, especially at twilight and at night [5; 8]. There is no ideal correction for all distances, but through objective measurement using the Visual Behavior Monitor (VBM) regarding distance measurement, ambient lighting and head posture will potentially determine a much more accurate setting and support the choice of IOL. Whatever additional technique is used, an important measure of success is the difference between the intended and the actual postoperative refractive outcome.