Finger or Light: Stimulation Sensitivity of Visual Startle in the Coma Recovery Scale-Revised for Disorders of Consciousness

Quantitative evaluation of the consciousness level of patients in a vegetative state using virtual reality and an eye-tracking system: A single-case experimental design study

ABSTRACTIt is important to distinguish patients in a minimally conscious state (MCS) from patients in a vegetative state (VS) when assessing disorders of consciousness (DOC) as prognosis, selection of therapy, and drug treatment could differ accordingly. Clinical evaluation of a patient's eye movements, such as visual startle, visual fixation, and visual pursuit, provides valuable evidence but is often subject to misdiagnosis. To minimize such misdiagnosis caused by human judgment, a virtual reality (VR) technology-based quantitative assessment method with an eye-tracking system is proposed in this study. The new VR system presented 3 stimuli to 20 healthy participants, and visual response data were recorded to define valid responses to each stimulus. Further, the newly defined stimuli were presented to five chronic patients in VS, and the system classified three of them as showing visual fixations that could not be verified through clinical assessment beforehand. The proposed system, as verified through such experimentation, suggests quantitative and objective evaluation methods for examining three visual functions of patients with DOC.

In vitro dissolution testing models of ocular implants for posterior segment drug delivery

The delivery of drugs to the posterior segment of the eye remains a tremendously difficult task. Prolonged treatment in conventional intravitreal therapy requires injections that are administered frequently due to the rapid clearance of the drug molecules. As an alternative, intraocular implants can offer drug release for long-term therapy. However, one of the several challenges in developing intraocular implants is selecting an appropriate in vitro dissolution testing model. In order to determine the efficacy of ocular implants in drug release, multiple in vitro test models were emerging. While these in vitro models may be used to analyse drug release profiles, the findings may not predict in vivo retinal drug exposure as this is influenced by metabolic and physiological factors. This review considers various types of in vitro test methods used to test drug release of ocular implants. Importantly, it discusses the challenges and factors that must be considered in the development and testing of the implants in an in vitro setup.