In megalopapilla the optic disc diameter exceeds 2.1 mm (or surface area more than 2.5 mm2[1]) with an increased cup-to-disc ratio.
Type 1, which is the most common, is bilateral with a normal configuration of the optic cup.
[5] Type 2 is unilateral with a superiorly displaced cup that eliminates the adjacent neuro-retinal rim.
[6] Since the clinical appearance of megalopapilla resembles that of glaucomatous optic disc, it should be differentiated from Normal tension glaucoma and other pseudo-glaucomatous diseases.
[4] Bock and Franceschetti were the first to use the term megalopapilla to describe larger-than-normal optic disks.