Principles of Ophthalmology focuses on the principles, methodologies, and approaches involved in ophthalmology. The manuscript first offers information on the mammalian globe, including optical divergence, asymmetry of the cornea, globe, and ciliary muscle, iris and dilation of the pupil, and asymmetry of the ciliary region in mammalia and its relation to vision. The text then ponders on the angle of the anterior chamber in mammalia, as well as analogous distribution of the intra-ocular and intra-granial contents; communication between the angle and the suprachoroidal space in mammalia; interstitial fibrosis of the ciliary muscle; and the carnivorous type of angle. The publication takes a look at the mechanism of accommodation and intra-ocular pressure. Discussions focus on problems arising from the alleged high physiological level of the intra-ocular pressure; physiological equilibrium between the intra-ocular and intra-cranial pressures; and clinical proof of the venous level of the intra-ocular pressure. The text is a valuable source of data for ophthalmologists and readers interested in ophthalmology.