The Dunedin Multidisciplinary Health and Development Study is a visionary project that was started in the early 1970s and continues to yield fascinating insights into human ageing and our interaction with the environment. Over 90% of the babies born in Dunedin during April 1972 to March 1973 were enrolled into this longitudinal cohort study (1.037 births), and after 45 years they continue to have 94% retention of all the surviving study members so the observations are fairly representative of the New Zealand population. Along the way this study has looked at countless associations and connections, the long term effects of childhood development and trauma, allergies and diet, tobacco and cannabis, and how these childhood factors relate to aging and health in middle age. When it comes to eyes and vision, ophthalmologist Dr Graham Wilson and his team of collaborators in the Dunedin Study have looked at how findings in the eye contribute to measurements of biological ageing as well as several other studies.
Recently a medical student, now junior doctor, Dr Aqeeda Singh, together with the team at the Dunedin Study, Dr Wilson, and myself, reviewed comprehensive eye examination findings from the participants at age 45. The goal was to consider how many of the participants had glaucoma, which made this the first estimate of glaucoma prevalence in New Zealand. Until now, we have assumed that the prevalence in Australian studies was similar in New Zealand, but it is important to test this assumption. The study also allowed us to look at how new optical coherence tomography (OCT) scanners affect the estimated prevalence of glaucoma.
At age 45 there were 7 people with glaucoma (0.8%), plus 1.7% with raised intraocular pressure (IOP), plus 7.3% who were glaucoma suspects. Nearly all of the glaucoma suspects were suspected based on the OCT scan, and there was another 8% who had abnormal OCT scans but were normal in every other measure. It was a little surprising that all glaucoma patients had normal IOP, all those with raised IOP had normal healthy optic nerves.
This prevalence estimate of 0.8% is in line with other populations, and we plan to measure the incidence of new glaucoma cases as they age into the future. Perhaps the most important finding from this study was that it would be unwise to do OCT scans on the whole community, because nearly all of the people with abnormal scans are actually healthy. Screening for glaucoma remains a subtle and challenging issue.
Author: Dr Jesse Gale