A 66-year-old man with diabetes and new-onset vision difficulties undergoes an exam in which a small amount of pressure is applied to the eye by a tiny device or by a warm puff of air. This exam is:

Choice A reason: Fluorescein angiography visualizes retinal blood vessels using a dye, not to measure intraocular pressure. Choice B reason: This is correct. Tonometry measures intraocular pressure by applying slight pressure to the eye, often using an air puff or contact device, which is important in glaucoma assessment. Choice C reason: Slit lamp examination allows detailed visualization of anterior eye structures, not intraocular pressure measurement. Choice D reason: Computed tomography provides cross-sectional imaging of the eye or orbit but does not measure eye pressure.