Purpose
RMD has been associated with choroidal thinning and significant progression to advanced AMD. We looked for association between genetics and choroidal thickness (CTh) in RMD, aka subretinal drusenoid deposits (SDD), using spectral domain optical coherence tomography (SD-OCT).
Methods
We retrospectively identified 29 patients (55 eyes) from a single institution who presented with a reticular pattern in scanning laser ophthalmoscope imaging and SDD in SD-OCT imaging in both eyes. No advanced AMD or large soft drusen were present. Genotyping at the CFH and ARMS2 loci was determined. A total of 55 CTh measurements were taken for each study eye (5 scans/eye,11 fixed points,~550um apart/scan). For most eyes, the five scans included two superior to the fovea, one foveal, and two inferior. We divided patients into 3 groups based on CFH genotype [wild type (T/T), heterozygous (T/C), and homozygous for the risk allele (C/C)] and 3 analogous groups based on ARMS2 genotype. We calculated mean CTh in the superior, foveal, and inferior macula for each group and performed a one-way ANOVA and a paired T test to determine significance.
Results
The mean age was 84±7 with 83% (24/29) females. At the ARMS2 locus, 7 subjects were wild type, 16 were heterozygous, and 6 were homozygous risk. The corresponding CFH groups numbered, 5, 16 and 8. CTh means for all 55 eyes were 164±59, 160±59, and 157±55 um for the superior, foveal, and inferior macula, respectively. Statistical significance was found when comparing the three CTh means within the ARMS2 genotypes, (P= 0.032; 0.012; 0.006). There also was significance when comparing the CTh means between the ARMS2 wild type (134±39, 124±40, 125±41) versus the homozygous risk (194±59, 189±56, 192±62), (P= 0.034; 0.024; 0.026). There was no statistical significance found between the CTh means within the CFH genotypes.
Conclusions
ARMS2 genotype, but not CFH genotype, appears to be correlated with CTh in the high risk AMD phenotype of RMD, with increasing load of the risk allele associated with increasing CTh at all locations. To our knowledge, this is the first reported association of an AMD risk allele with choroidal structure. Further study, especially of the relationship with RMD, is warranted.