Glaucoma causes a distinct type of optic nerve damage that leads to irreversible visual field defects and blindness, if left untreated. Early detection is key. Many patients’ glaucoma goes undiagnosed or undertreated because central vision is often the last to go, when the disease is in advanced stages.

A recent study investigated central visual field (VF) defects present in four phenotypes of glaucomatous optic discs and found the severity and prevalence of central VF loss varies among phenotypes.

The cross-sectional study included 448 eyes of 309 patients with definite or suspected glaucoma and a 24-2 VF mean deviation better than -12dB and a 10-2 VF. The researchers identified four optic disc phenotypes in the study population: focal ischemic (n=121), generalized cup enlargement (n=109), senile sclerotic (n=152) and myopic glaucoma (n=66).

Among all phenotypes, 24-2 VF mean deviation values were similar, but eyes with generalized cup enlargement demonstrated a higher 10-2 VF mean deviation value and lower 24-2 VF and 10-2 VF pattern standard deviations than the other three phenotypes.

Eyes with the focal ischemic phenotype demonstrated the highest prevalence of abnormal 10-2 VF (78.5%), while those with generalized cup enlargement had the lowest at 50.5% (Table 1). In eyes suspect for glaucoma, the myopic glaucoma and focal ischemic phenotypes had the highest prevalence of abnormal 10-2 VF (31.2% and 23.5%, respectively). The lowest prevalence was found in eyes with generalized cup enlargement (8.6%). In eyes with mild glaucoma, the prevalence of abnormal 10-2 VF was highest in eyes with focal ischemia (79.2%) and lowest in eyes with generalized cup enlargement (44.4%).

The researchers concluded that glaucomatous eyes with focal ischemic and myopic optic disc phenotypes are more likely to have 10-2 VF loss, especially in early stages of the disease. They noted that these patients may benefit more from testing with both 10-2 VF and 24-2 VF.