This document is a study of optical fault injection attacks and countermeasures against them, with particular emphasis on an evaluation and comprehensive comparison of the different methods, techniques, structures and implementations which can be used as countermeasures. Initially, it is examined why this topic is significant, important and relevant for computer security, especially from the perspective of a relevant business firm, especially regarding financial issues, such as cost. Then we make a comprehensive and detailed introduction to optical fault injection attacks against smart card chips and the countermeasures employed against such attacks, including a review of the current solution of using light sensors as countermeasures and the potentialshortcomings of this solution. We continue by identifying and investigating other potential alternative countermeasures against optical fault induction attacks. We then proceed to make a full evaluation and comparison of them, including some of their different implementations, regarding the balance between the diverse costs required for their implementation in a smart card chip and the level of protection they would offer. Additionally, we also relate the results of this comparison to the results that the current solution provides. We then go on to discuss what future work we have identified that it may be needed regarding this field. Different innovative approaches are discussed, and the thesis concludes with some additional remarks regarding these proposals and some final conclusions drawn from the comparison between currently used and alternative countermeasures.