To investigate the clinical characteristics of first-degree relatives with primary open-angle glaucoma (POAG).

Forty-four POAG patients (22 pairs of eyes from 2 first-degree relatives) were followed for an average of 3.3 years. Baseline characteristics and follow-up data were analyzed. Baseline data consisted of baseline intraocular pressure (IOP), central corneal thickness (CCT), spherical equivalent, visual field mean deviation (VF MD) and average retinal nerve fiber layer (RNFL) thickness measured using optical coherence tomography (OCT). Follow-up data consisted of mean follow-up IOP, mean IOP reduction from baseline (%) and progression rates determined by linear regression analysis of either VF MD value or OCT RNFL thickness. Mean data of both eyes and the worse eye were compared between first-degree relatives of the same family.

Among the 22 families, 16 pairs of eyes were from parent/offspring and 6 from siblings. No difference in mean baseline IOP and CCT were found between first-degree relatives. The older patients in parent-offspring families showed significantly more advanced glaucoma in terms of both VF and RNFL thickness, but were less myopic; however, no differences in variables were found between relatives in the 6 families composed of siblings. Among the 22 families, worse baseline VF MD was observed in younger patients compared with the older patients in 4 families. Mean follow-up IOP, mean IOP reduction from baseline, and progression rate did not differ between the older and the younger patient in each family.

In our study, similar characteristics in terms of baseline IOP, IOP response to medication, and glaucoma progression rate were found in members of the same family. However, in some of the families, the younger patient had poorer baseline severity and more aggressive characteristics compared with the older patient, suggesting the clinical course of the disease may vary among first-degree relatives.