Effect of cataract and pupil size on image quality with confocal scanning laser ophthalmoscopy

L. Zangwill, I. Irak, C. C. Berry, V. Garden, M. de Souza Lima and R. N. Weinreb
Department of Ophthalmology, University of California-San Diego, La Jolla, USA.

OBJECTIVE: To determine the effect of pupil size and cataract on the reproducibility and image quality obtained with confocal scanning laser ophthalmoscopy. METHODS: Three image series were obtained with a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph, Heidelberg, Germany) before and after pupillary dilation in each of 39 subjects (8 normal subjects, 5 glaucoma suspects, and 26 patients with glaucoma). The cataract density was measured with both a lens opacity meter and the Lens Opacities Classification System III system. The image quality of each image series was subjectively scored on a scale of 0 (poor) to 9 (high) by 2 independent observers who were unaware of the cataract density and pupil size during image acquisition. The image quality and reproducibility were objectively evaluated using the SD of the mean topography image of each subject. RESULTS: The mean pupil diameter in all subjects before and after dilation was 2.5 +/- 0.8 mm and 5.8 +/- 1.4 mm, respectively. After pupillary dilation, both the mean image quality score and mean SD of the mean topography image improved (from 4.5 +/- 3.5 to 7.4 +/- 2.3 and from 48.6 +/- 18.8 microns to 35.6 +/- 15.5 microns, respectively). The quality score of the images that were obtained before pupillary dilation was associated with the pupil size and density of nuclear and posterior subcapsular cataracts. The SD of the mean topography images that were obtained before pupillary dilation increased with a decreasing pupil size (P = .003) and an increasing density of the nuclear (P < .03), cortical (P = .02), and posterior subcapsular (P = .002) opacity. CONCLUSIONS: Although pupillary dilation improved the image quality in most subjects, the improvement was sometimes small. Those subjects with small undilated pupils and/or cataracts may benefit most from pupillary dilation.

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

Effect of pupillary dilatation on glaucoma assessments using optical coherence tomography
Smith et al.
Br. J. Ophthalmol. 2007;91:1686-1690.
ABSTRACT | FULL TEXT  

Some dissociating factors in the analysis of structural and functional progressive damage in open-angle glaucoma
Hudson et al.
Br. J. Ophthalmol. 2007;91:624-628.
ABSTRACT | FULL TEXT  

Measurement Variability in Heidelberg Retina Tomograph Imaging of Neuroretinal Rim Area
Owen et al.
IOVS 2006;47:5322-5330.
ABSTRACT | FULL TEXT  

Influence of cataract on optical coherence tomography image quality and retinal thickness.
van Velthoven et al.
Br. J. Ophthalmol. 2006;90:1259-1262.
ABSTRACT | FULL TEXT  

Detecting glaucoma with RADAAR: the Bridlington Eye Assessment Project
Hawker et al.
Br. J. Ophthalmol. 2006;90:744-748.
ABSTRACT | FULL TEXT  

Asymmetry in Optic Disc Morphometry as Measured by Heidelberg Retina Tomography in a Normal Elderly Population: The Bridlington Eye Assessment Project
Hawker et al.
IOVS 2005;46:4153-4158.
ABSTRACT | FULL TEXT  

Factors affecting the test-retest variability of Heidelberg retina tomograph and Heidelberg retina tomograph II measurements
Strouthidis et al.
Br. J. Ophthalmol. 2005;89:1427-1432.
ABSTRACT | FULL TEXT  

Laser Scanning Tomography of the Optic Nerve Head in a Normal Elderly Population: The Bridlington Eye Assessment Project
Vernon et al.
IOVS 2005;46:2823-2828.
ABSTRACT | FULL TEXT  

Optic nerve head morphometry in healthy adults using confocal laser scanning tomography
Hermann et al.
Br. J. Ophthalmol. 2004;88:761-765.
ABSTRACT | FULL TEXT  

Approach for Identifying Glaucomatous Optic Nerve Progression by Scanning Laser Tomography
Tan and Hitchings
IOVS 2003;44:2621-2626.
ABSTRACT | FULL TEXT  

Reasons for Rim Area Variability in Scanning Laser Tomography
Tan et al.
IOVS 2003;44:1126-1131.
ABSTRACT | FULL TEXT  

Imaging a Child's Fundus Without Dilation Using a Handheld Confocal Scanning Laser Ophthalmoscope
Kelly et al.
Arch Ophthalmol 2003;121:391-396.
ABSTRACT | FULL TEXT  

Optic Disc and Visual Field Changes in a Prospective Longitudinal Study of Patients With Glaucoma: Comparison of Scanning Laser Tomography With Conventional Perimetry and Optic Disc Photography
Chauhan et al.
Arch Ophthalmol 2001;119:1492-1499.
ABSTRACT | FULL TEXT  

Assessment of Optic Disc Topography for Diagnosing and Monitoring Glaucoma
Weinreb
Arch Ophthalmol 1998;116:1229-1231.
FULL TEXT