From the early centuries, theologians utilized scientific theories to explain metaphysical issues. As a result, the subject of vision was analysed both in the epistemology and the physics sections of kalām texts. However, one of the fields in which the relationship between kalām and science is most evident centres on optics and the discussion of the vision of God in the Hereafter (ruʾyat Allāh). Theologians from different schools, such as Muʿtazila and Ahl al-Sunnah, discussed this topic with rational and scientific proofs. With the influence of al-Kindī, the Muʿtazila adopted the extramission theory, which was previously advocated by philosophers such as Galen and Euclid. According to this theory, vision occurs when the ray emanating from a sound eye converges on an object that has the quality of being seen in a suitable environment for this purpose. Subsequently, Fakhr al-Dīn al-Rāzī criticized all the theories that had come before him, especially the intromission and extramission models. After stating that vision is a relation between the eye and the observed object, al-Rāzī also touched upon its conditions. Based on the elements of Ibn Haythamian modified intromission theory, al-Rāzī argued that the rays that cause vision emanate from the object, not from the eye, and that this event occurs through a cone that begins in the object and ends in the eye. He also partially carried this idea to different texts in which he explained the subject of vision of God (ruʾyat Allāh). This approach was systematized by ʿAḍud al-Dīn al-ʿĪjī who formed the main structure of the texts in the following period.