Clinical Study
Eye (2007) 21, 169–176. doi:10.1038/sj.eye.6702151; published online 26 May 2006
Characteristics of progression of early Age-related macular degeneration: the Cardiovascular Health and Age-related maculopathy Study
G Tikellis1, L D Robman1,2, P Dimitrov1, C Nicolas1, C A McCarty3,1 and R H Guymer1,2
- 1Department of Ophthalmology, Centre for Eye Research Australia, University of Melbourne, East Melbourne, Victoria, Australia
- 2Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia
- 3Marshfield Clinic Research Foundation, Wisconsin, USA
Correspondence: G Tikellis, Department of Ophthalmology, Centre for Eye Research Australia, University of Melbourne, Locked Bag 8, East Melbourne, Victoria, 8002, Australia. Tel: +61 3 9929 8571; Fax: +61 3 9662 3859; E-mail: gtike@unimelb.edu.au
Received 1 June 2005; Accepted 17 September 2005; Published online 26 May 2006.
Abstract
Aims
To determine the risk of age-related macular degeneration (AMD) progression posed by the presence of each early AMD characteristic.
Methods
A prospective cohort study of 254 participants aged 50 years and older, all with early AMD features at their baseline visit followed for an average of 7 years. Stereoscopic colour fundus photographs were graded for early AMD features using the International Classification System. AMD status was stratified into six exclusive levels along a continuum of disease severity according to drusen type, pigmentary abnormalities, or late AMD. Progression was assessed according to three definitions: a change between or within a severity level, or by side by side grading.
Results
The progression rate of early AMD ranged between 3.4 and 4.67% per annum depending upon the definition used. In total, 15 (6%) cases progressed from early AMD to the late complication of AMD. After controlling for age and smoking, cases with soft indistinct drusen at baseline were at a greater risk of progressing from early to late AMD than were cases without this characteristic (OR=3.72, 95%CI 1.20–11.54; P=0.02).
Conclusion
Our proposed definitions of AMD progression give rates that are consistent with current knowledge of progression and its determinants. Each early AMD characteristic conveys its own risk of progression to an eye, with soft indistinct drusen carrying the greater risk. An international consensus on what defines AMD progression would greatly help the research community when trying to assess the importance of new risk factors and the effectiveness of novel interventions.
Keywords:
age-related macular degeneration, age-related maculopathy, progression, drusen
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