Secondary glaucoma can be due to an underlying medical condition, trauma, or medication side effects, unlike primary glaucoma where no immediate cause is apparent. Secondary glaucoma still involves increased ocular pressure leading to optic nerve damage. It affects 0.3-0.8% of adults, with prevalence increasing with age.^17,19

• ·       uveitic inflammatory glaucoma due to inflammation of the uvea (uveitis);

• ·       neovascular glaucoma with blood vessels growing and covering the drainage system, (associated with conditions such as diabetic retinopathy);

• ·       pigmentary glaucoma where pigment from the iris flakes off (pigment dispersion syndrome or PDS), blocking the drainage;

• ·       traumatic glaucoma from an eye injury increasing eye pressure, sometimes not developing until years later.

Normal tension glaucoma (NTG) is optic nerve damage when ocular pressure is in the normal range. The mechanism is not fully understood but may involve fragility in the optic nerve. It can be hard to detect as symptoms do not appear until it is very advanced; central vision tends to be damaged sooner than in other types of glaucoma.⁵