Abstract
Aim: We aimed to estimate the prevalence of glaucoma in New Zealand using a population-based birth cohort of 45-year-olds.
Methods: Study members of the Dunedin Multidisciplinary Health & Development Study participated (n=938 out of 1037 births (91%)). The data collected included visual acuity, visual field (VF), refraction, central corneal thickness, intraocular pressure (IOP), axial length, spectral domain optical coherence tomography (OCT), and non-mydriatic fundus photographs. Two phthalmologists reviewed data independently to generate a consensus glaucoma status: "Normal" if no suspicion of glaucoma; "Ocular hypertension" if IOP >21 mmHg; "Glaucoma suspect" if optic disc photograph was suspicious for glaucoma with no more than borderline or non-corresponding VF or OCT abnormalities; and "Glaucoma" if optic disc photograph was suspicious for glaucoma and there were corresponding abnormalities of the OCT or VF.
Results: Of 891 participants with sufficient data to assign a glaucoma status, 804 were "Normal" (90.2% [CI 88.3-92.2]), 15 were "Ocular hypertension" (1.68% [95% confidence interval (CI) .84-2.5]), 65 were "Glaucoma suspect" (7.30% [95% CI 5.6-9.0]), and 7 were classified as "Glaucoma" (0.79% [95% CI 0.21-1.4]). An additional 73 participants (8.2%, [95% CI 6.3%-10%]) had abnormalities on the OCT scan but were not deemed to be glaucoma suspects.
Conclusion: The prevalence of glaucoma in New Zealand is between 0.2% and 1.4%, consistent with other population-based studies in the same age group. The study highlights the sensitivity of OCT and the potential for misinterpretation and over-investigation.