Quantitative Analysis of Cone Photoreceptor Distribution and Its Relationship with Axial Length, Age, and Early Age-Related Macular Degeneration

Ryo Obata,Yasuo Yanagi,Steven Barnes

doi:10.1371/journal.pone.0091873

Ryo Obata, Yasuo Yanagi + Show 1 more

Open Access

https://doi.org/10.1371/journal.pone.0091873

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Journal: PloS one	Publication Date: Mar 14, 2014
Citations: 63	License type: CC BY 4.0

Affiliation: The University of Tokyo

Abstract

PurposeIt has not been clarified whether early age-related macular degeneration (AMD) is associated with cone photoreceptor distribution. We used adaptive optics fundus camera to examine cone photoreceptors in the macular area of aged patients and quantitatively analyzed its relationship between the presence of early AMD and cone distribution.MethodsSixty cases aged 50 or older were studied. The eyes were examined with funduscopy and spectral-domain optical coherence tomography to exclude the eyes with any abnormalities at two sites of measurement, 2° superior and 5° temporal to the fovea. High-resolution retinal images with cone photoreceptor mosaic were obtained with adaptive optics fundus camera (rtx1, Imagine Eyes, France). After adjusting for axial length, cone packing density was calculated and the relationship with age, axial length, or severity of early AMD based on the age-related eye disease study (AREDS) classification was analyzed.ResultsPatient’s age ranged from 50 to 77, and axial length from 21.7 to 27.5 mm. Mean density in metric units and that in angular units were 24,900 cells/mm2, 2,170 cells/deg2 at 2° superior, and 18,500 cells/mm2, 1,570 cels/deg2 at 5° temporal, respectively. Axial length was significantly correlated with the density calculated in metric units, but not with that in angular units. Age was significantly correlated with the density both in metric and angular units at 2° superior. There was no significant difference in the density in metric and angular units between the eyes with AREDS category one and those with categories two or three.ConclusionAxial length and age were significantly correlated with parafoveal cone photoreceptor distribution. The results do not support that early AMD might influence cone photoreceptor density in the area without drusen or pigment abnormalities.

Highlights

Age-related macular degeneration (AMD) is a leading cause of blindness in developed countries. [1] age-related macular degeneration (AMD) has two stages; i.e., early AMD and late AMD
Drusen and pigment abnormalities are the hallmarks of early AMD. [2,3] They are usually recognized in focal areas, but the pathological investigation proved diffusely distributed membranous deposits on the basement membrane of the retinal pigment epithelium throughout the macula. [4,5,6] Early AMD is predisposed to late AMD, which is characterized by development of choroidal neovascularization or progressive retinochoroidal atrophy resulting in severe vision loss
Some previous studies pathologically demonstrated that cone photoreceptors were disorganized at the fovea or parafovea in early AMD patients. [9,11] Other studies reported that central visual field, [12] cone adaptation, [13] blue cone sensitivity, [14] focal ERG, [15] and multifocal ERG [16] showed impaired cone function even in the early stage of the disease

Summary

Introduction

Age-related macular degeneration (AMD) is a leading cause of blindness in developed countries. [1] AMD has two stages; i.e., early AMD and late AMD. Photoreceptor loss is documented in early AMD, disorganization of rod photoreceptor has been well demonstrated both pathologically [8,9] and physiologically. Some previous studies pathologically demonstrated that cone photoreceptors were disorganized at the fovea or parafovea in early AMD patients. [9,11] Other studies reported that central visual field, [12] cone adaptation, [13] blue cone sensitivity, [14] focal ERG, [15] and multifocal ERG [16] showed impaired cone function even in the early stage of the disease. It has been demonstrated pathologically that cone photoreceptor density was decreased in the parafovea of three eyes with early AMD. [5] another study reported the photoreceptor damage was confined to areas directly overlying drusen. It has been demonstrated pathologically that cone photoreceptor density was decreased in the parafovea of three eyes with early AMD. [5] another study reported the photoreceptor damage was confined to areas directly overlying drusen. [17]

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