Macular Pigment Density in Healthy Subjects Quantified With a Modified Confocal Laser Scanning Ophthalmoscope

Abstract

Abstract: : Purpose:In the industrialized world age-related macular degeneration (AMD) is the leading cause for legal blindness beyond the age of 50 years. Recent studies indicate that the density of the macular pigment (MP) may play a central role in the development and progression of age-related maculopathy (ARM). We present a new method for the measurement of macular pigment density with a modified confocal scanning laser ophthalmoscope and compare macular pigment density values obtained from reflectance and autofluorescence images. Methods:A modified confocal scanning laser ophthalmoscope (Heidelberg Engineering, Heidelberg, Germany) was optimized for fundus reflectance and autofluorescence images at 488 and 514 nm. Both, reflectance and autofluorescence images were used to calculate macular pigment density maps. To obtain MP density maps two images recorded at 488 nm and 514 nm illumination wavelengths were converted to log reflectance maps and digitally subtracted. For autofluorescence imaging two different band pass barrier filters with a short wavelength cut off at 530 nm and 560 nm were used. After correction for the difference in the MP absorption at 488 and 514 nm, for the lens density and for differences in the intensity of the laser light at different wavelengths, MP density was evaluated within 2 degrees around the foveal center. In this study we included 20 healthy subjects aged form 18 - 50 years. Results:Average macular pigment density ranged between 0.17 density units (D.U.) and 0.28 D.U. depending on the different techniques. Using the reflectance method mean macular pigment density was 0.170.02 D.U., whereas a MP density of 0.270.06 D.U. and 0.280.06 D.U. resulted from autofluorescence images with the 530 nm or 560 nm barrier filter respectively. Conclusion:This study demonstrates the feasibility of macular pigment density measurement with a modified confocal scanning laser ophthalmoscope. In agreement with previous studies (Delori et al 2001) we found higher macular pigment density values calculated from autofluorescence images than from reflectance images. These differences may be related to systematic differences within the techniques. This new technique will enable us to perform prospective studies on the influence of macular pigment density in ARM.

Keywords: 462 macular pigment • 430 imaging/image analysis: clinical • 308 age-related macular degeneration