Evaluation of Cardiovascular Disease as a Risk Factor for Sight Threatening Reticular Drusen.

Background: Age-related macular degeneration (AMD) is the most common cause of permanent blindness in the industrialised world affecting adults older than 50 years. Reticular drusen (RD), which manifest as subretinal deposits located between the retinal pigment epithelium and the inner ellipsoid zone, have been identified as a strong predictor of developing the most serious sight threatening forms of AMD. RD can occur in the absence of any other AMD signs leading some to suggest it is a manifestation of a systemic condition. Several studies have reported a strong association between RD and cardiovascular disease (CVD), however these are mostly small case-control studies carried out within ophthalmic clinics raising the possibility of considerable confounding. Therefore we sought to examine the association between RD and CVD within a predominantly CVD cohort using Optos wide-field retinal images captured as part of the SCOT-HEART (SH) study.
Aim: To explore the association of CVD as a risk factor for RD.
Methods The SH study was undertaken in Scotland between 2010-2014 on 9849 patients aged 18-75 years assessed for suspected angina due to CVD. We used data from a sub-study which involved retinal imaging in addition to the standard procedures. Utilising Optos wide-field colour images specific features of AMD were graded according to standardised protocols. Standardised grading grids were used to record the spatial location of AMD features. Critical to this grading was determining the deposits of RD which appear as an interlacing network (pattern) of drusen deposits in the mid-periphery of the retina. CVD was categorised as mild, moderate or obstructive Descriptive statistics were conducted on all participants. Logistic regression analysis was used to report Odds ratios (OR), with corresponding 95% confidence intervals (CI).

Results: To date 277 participants have been graded. Mean age was 58 years (range: 27-75 years and standard deviation [SD]: 9.52), 155 male, (56%). Of these participants 78 had no CVD (28%). Eight of the 277 participants (2.9%) were identified with RD in both eyes. The mean age of these participants with bilateral RD was 57 years and 75% were female. Four of the participants with RD had no CVD (50%), 2 (25%) had mild CVD, 1 (12.5%) had moderate CVD and 1 (12.5%) had obstructive CVD. Most participants with RD also had additional drusen deposits independent of the RD detected (75%). Logistic regression analysis conducted on all participants indicated after the adjustment for potential confounders (age, gender, smoking habit) that no significant association between CVD and RD (OR, 0.56; CI, 0.11-2.85; p= 0.49).

Conclusion: The data analysed to date provides little support for a relationship between CVD and RD. In keeping with previous research, a greater presence of RD amongst females was detected.