Ophthalmic Surgery, Lasers and Imaging Retina

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Clinical Science 

Macular Thickness Measurements in Normal Eyes Using Spectral Domain Optical Coherence Tomography

Giovanni Gregori, MD; Robert W. Knighton, PhD; Carmen A. Puliafito, MD, MBA; John E. Legarreta, BFA; Omar S. Punjabi, MD; Geeta A. Lalwani, MD

Abstract

BACKGROUND AND OBJECTIVE: Knowledge of the macular thickness in a normal population is important for the evaluation of pathological macular change. The purpose of this study was to define and measure macular thickness in normal eyes using spectral domain optical coherence tomography (OCT).

PATIENTS AND METHODS: Fifty eyes from 50 normal subjects (29 men and 21 women, aged 22 to 68 years) were scanned with a prototype Cirrus HD-OCT system (5 µm axial resolution) (Carl Zeiss Meditec, Inc.). The proprietary Cirrus segmentation algorithm was used to produce retinal thickness maps, which were then averaged over 9 regions defined by a circular target centered at the true fovea location. The macular thickness of 13 subjects scanned with both HD-OCT and StratusOCT were compared.

RESULTS: After centering the fovea, the mean and standard deviation values for retinal thickness measurements were calculated point wise and averaged on standard regions. For patients scanned with both systems, the thickness measurements from HD-OCT were approximately 50 µm larger than those from StratusOCT. The difference between the two measurements decreased somewhat with eccentricity.

CONCLUSION: Using HD-OCT, it is possible to acquire retinal data sets containing an unprecedented number of data points. Furthermore, it is possible to use OCT fundus images to evaluate the scan quality and to center the measurement at the fovea. These advantages, together with good automated segmentation, can produce more accurate retinal thickness measurements. Incorporation of the photoreceptor layer in the measurements is anatomically meaningful and may be significant in evaluating various retinal pathologies and visual acuity outcomes.

[Ophthalmic Surg Lasers Imaging 2008;39:S43-S49.]

Abstract

BACKGROUND AND OBJECTIVE: Knowledge of the macular thickness in a normal population is important for the evaluation of pathological macular change. The purpose of this study was to define and measure macular thickness in normal eyes using spectral domain optical coherence tomography (OCT).

PATIENTS AND METHODS: Fifty eyes from 50 normal subjects (29 men and 21 women, aged 22 to 68 years) were scanned with a prototype Cirrus HD-OCT system (5 µm axial resolution) (Carl Zeiss Meditec, Inc.). The proprietary Cirrus segmentation algorithm was used to produce retinal thickness maps, which were then averaged over 9 regions defined by a circular target centered at the true fovea location. The macular thickness of 13 subjects scanned with both HD-OCT and StratusOCT were compared.

RESULTS: After centering the fovea, the mean and standard deviation values for retinal thickness measurements were calculated point wise and averaged on standard regions. For patients scanned with both systems, the thickness measurements from HD-OCT were approximately 50 µm larger than those from StratusOCT. The difference between the two measurements decreased somewhat with eccentricity.

CONCLUSION: Using HD-OCT, it is possible to acquire retinal data sets containing an unprecedented number of data points. Furthermore, it is possible to use OCT fundus images to evaluate the scan quality and to center the measurement at the fovea. These advantages, together with good automated segmentation, can produce more accurate retinal thickness measurements. Incorporation of the photoreceptor layer in the measurements is anatomically meaningful and may be significant in evaluating various retinal pathologies and visual acuity outcomes.

[Ophthalmic Surg Lasers Imaging 2008;39:S43-S49.]

Authors

From the Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida.

Accepted for publication April 11, 2008.

Presented as a poster at the Association for Research in Vision and Ophthalmology annual meeting, May 8, 2007, Fort Lauderdale, Florida.

Supported in part by Research to Prevent Blindness, Inc., New York, New York. Research funding provided in part by a grant from Carl Zeiss Meditec, Inc. (JEL, GG, OSP, RWK, CAP) and NIH Grant P30EY014801.

Dr. Puliafito is a Research and Clinical Consultant for Carl Zeiss Meditec, Inc. Dr. Puliafito did not participate in the editorial review of this manuscript.

Dr. Knighton is the principal investigator on a research agreement with Carl Zeiss Meditec, Inc., to improve spectral domain optical coherence tomography for ophthalmic diagnosis.

Address correspondence to Giovanni Gregori, PhD, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10th Avenue, Miami, FL 33136.

10.3928/15428877-20080715-02

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