Dr Ashish Markan on Instagram: "The Goldmann applanation tonometer measures intraocular pressure (IOP) by determining the force needed to flatten a specific area of the cornea. This force is then converted to a pressure reading, with 10 times the flattening force (in grams) equaling the IOP in mmHg. The tonometer uses a prism that contacts the cornea, and a split-image prism highlights the tear film meniscus. The IOP is read when the meniscus arcs just touch, indicating the 3.06 mm applanated ar