ARVO 2018 - Part 3

The annual Association for Research in Vision and Ophthalmology (ARVO) conference moved off mainland America to Hawaii for the first time in May 2018, which I'm sure helped to boost attendance and was a much shorter travel time for us Australasians. With over 10,000 attendees and thousands of research posters, papers and symposiums presented over 5 days, it was a mind blowing nerdy extravaganza. Here are a bunch of cutting edge research pieces which I posted to the Myopia Profile Facebook group at the time. I've decided to accompany them with beautiful Hawaiian sunset photos I took during our visit.

Part 1 and Part 2 are here.

Does a child’s historical myopia progression predict future fast progression? Analysis of over 2000 visits from the large CLEERE (Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error) Study data set indicate that the answer is no - looking at axial length and spherical equivalent refraction (SER) for one and two years previously has a minimal effect on predicting future fast progression. For children aged 7–14 years, 0.222 mm/year increase in axial length was the optimal fit for defining fast progression, and -0.375 D/year for SER. Yes, that latter number seems low - the abstract shows modest sensitivity and specificity of this definition, so it isn’t necessarily applicable to clinical practice and is more a function of this modelling. Nevertheless, these findings have relevance for myopia control studies - you don’t need to prove a child is a progressor for them to be a good candidate for study participation - and for clinical practice. The bottom line is that any myopic child is a progressor until proven otherwise, with this study indicating this can be the case regardless of previous history.

Has myopia prevalence in adults increased in sunny Australia? The landmark Blue Mountains Eye Study was undertaken about 20 years ago, and showed a prevalence of around 21%. It also found a higher prevalence of cataract in myopes. Almost all of these study participants, though, were born before WW2 without the same analysis yet being undertaken in the baby boomer generation. Two large population studies recently undertaken on adults aged 49-70 found prevalence of 30% and 36%. The authors felt this could be a slight underestimate as cataract surgery is done earlier now, and since myopes can have earlier onset cataract, some former myopes could have been counted as psuedophakic emmetropes. There were several interesting discussion points about baby boomers being the least sun protected generation, and of course the evolution of the visual environment. So even with our outdoorsy lifestyle in Australia, the Myopia shark is still biting.

Myopic macular degeneration (MMD) creeps that little bit closer - while an axial length of 26mm or greater has already been associated with increased risk of lifelong visual impairment, perhaps it's even less than that. Farzana Choudhury and colleagues in California studied a stable Chinese American population over 50 years of age, to look at the association between axial length and MMD. How did they define MMD? From the abstract: “MMD was assessed in a masked manner by an expert grader [using stereoscopic fundus photography]. A modified version of the Meta-Analysis for Pathologic Myopia (META-PM) was used to define MMD that included presence of tessellation, diffuse and patchy chorioretinal atrophy, atrophic macula, lacquer cracks, choroidal neovascularization, and Fuch’s spots.”

So here’s the punch line. Out of 1500 myopes, 32% had MMD. There was minimal risk up to around 24.6mm of axial length. There was a linear increase from 24.6 to 30mm, where each extra mm of axial length increased the odds ratio of MMD by 2.6 (double-and-a-half of the risk). EVERYONE with an AL of more than 31mm had MMD - check out the prevalence graph in the abstract! The authors concluded that axial lengths over 25.5mm are enough to greatly increase the odds of future MMD (at least in Chinese Americans) and so these patients need us to watch them more closely.

You can read Part 1 and Part 2 here.