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Effect of Unilateral Exudative Age-Related Macular Degeneration on Binocular Visual Function
Arch Ophthalmol. 2001;119:1725-1726.
INTRODUCTION
Age-related macular degeneration (AMD) is the leading cause of vision loss in people older than 65 years. Most cases of severe vision loss are related to the development of exudative AMD, which is characterized by the growth of abnormal vessels from the choroidal circulation. These abnormal vessels leak fluid and blood into the macula. Eventually, a fibrotic macular scar can form.
Symptoms of exudative AMD include blurred vision, metamorphopsia, relative central scotoma, dyschromatopsia, photopsias, and formed hallucinations.1-2 Individuals often complain of difficulty reading and recognizing facial features. Symptoms related to unilateral exudative AMD also might include reduced binocular visual function and abnormal depth perception. Although individuals might not report reduced binocular visual perception, many admit to closing the "bad eye" to improve their ability to see fine detail.
Report of a Case
A series of paintings by a Pennsylvania artist illustrates the effect of unilateral exudative AMD on binocular visual function. The artist is a 68-year-old woman with a 3-year history of AMD characterized by drusen with mild retinal pigment epithelial alterations in the right eye and a fibrovascular macular scar in the left eye (approximately 6 disc areas). Her vision is 20/20 OD and 6/200 OS. Her symptoms included reduced vision with her left eye and the need to occlude her left eye to perform tasks requiring fine visual acuity. Her symptoms were noticeable from the time of her initial vision loss and did not change significantly during the following 2 years.
She performed a series of oil paintings using monocular and binocular vision. Figure 1 was painted with her left eye occluded. This painting is remarkable for vibrant colors and fine detail. The peaches are well defined using bright colors; the leaves and branches are distinct using appropriate shadowing. Figure 2 was painted with her right eye occluded. There is marked derangement of the image quality and loss of detail, with an inability to distinguish the peaches, leaves, or branches. The vibrant colors are replaced by a brown-green amorphous smudge.
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Figure 1. Oil painting done by a patient with age-related macular degeneration with the left eye occluded.
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Figure 2. Oil painting done by a patient with age-related macular degeneration with the right eye occluded.
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Figure 3 demonstrates the adverse effect of unilateral exudative AMD on binocular visual function. When painting this figure, neither eye was occluded. There clearly is a detrimental effect of her "bad" left eye on her ability to perceive fine detail. She is unable to suppress the abnormal image from her left eye. As a result, the painting is notable for loss of detail. Two central objects are identifiable, although it is difficult to distinguish these objects as peaches. The details of the leaves, branches, and shadowing are lost.
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Figure 3. Oil painting done by a patient with age-related macular degeneration with both eyes open.
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Comment
Faubert and Overbury3 examined monocular and binocular spatial contrast sensitivity in older people with and without AMD. They measured contrast sensitivity thresholds using spatial sine wave gratings. Contrast thresholds were calculated using Michelson contrast ([Lmax - Lmin]/[Lmax + Lmin]), where Lmax and Lmin corresponded to the maximum and minimum luminances in the image, respectively. In almost half of the population with AMD, sensitivity to spatial information, as measured using spatial contrast sensitivity, was worse when both eyes were used together compared with when the stimuli were viewed with only one eye. They use the term "binocular inhibition" to describe this phenomenon and suggest that for some patients with visual impairment related to AMD, one eye might be better than two.
The effect of AMD on the visual perception of an artist has been examined previously.4 Terrence Billings, MD, a physician and trained artist, demonstrated the impact of AMD in a series of paired oil paintings using first the vision of both eyes and then the vision of his more severely affected right eye alone. In contrast to the artist described herein, the distortion and relative central scotoma of Dr Billings' more affected right eye had little impact on his ability to paint with both eyes together.
Exudative AMD can have a profound effect on monocular and binocular visual function. In some individuals with unilateral vision loss related to exudative AMD, a relative degree of visual impairment can occur when visualizing objects with both eyes simultaneously. The possibility of binocular inhibition should be considered when providing visual rehabilitative services for individuals with unilateral vision loss related to AMD.
AUTHOR INFORMATION
David A. Quillen, MD
Hershey, Pa
Corresponding author: David A. Quillen, MD, Department of Ophthalmology, Penn State University, PO Box 850, Hershey, PA 17033 (e-mail: daq2{at}psu.edu).
REFERENCES
1. Fine AM, Elman MJ, Ebert JE, Prestia PA, Starr JS, Fine SL. Earliest symptoms caused by neovascular membranes in the macula. Arch Ophthalmol. 1986;104:513-514.
ABSTRACT
2. Brown GC, Murphy RP. Visual symptoms associated with choroidal neovascularization: photopsias and the Charles Bonnet syndrome. Arch Ophthalmol. 1992;110:1251-1256.
ABSTRACT
3. Faubert J, Overbury O. Binocular vision in older people with adventitious visual impairment: sometimes one eye is better than two. J Am Geriatr Soc. 2000;48:375-380.
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4. Sperduto RD, Hagler WS, Ferris FL, Billings TE. Senile macular degeneration: an artist's view. JAMA. 1983;250:2506-2507.
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SECTION EDITOR: W. RICHARD GREEN, MD
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