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Visual problems of the aging musician
SURVEY OF O P H T H A L M O L O G Y VOLUME 40. NUMBER 4 . JANUARY-FEBRUARY1996
PERSPECTIVES IN REFRACTION MELVIN L. RUBIN, EDITOR
Visual Problems of the Aging Musician EDDIE F. KADRMAS, MD, PHD, JOHN A. DYER, MD, AND GEORGE B. BARTLEY, MD
Department of Ophthalmology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA Abstract. The presbyopic musician presents the ophthalmologist with an often demanding set of visual needs. Many modalities, some necessarily creative, are available to aid older musicians in their vision-dependent art. (Surv Ophthalmol 40:338-341, 1996)
Key words, musician
•
presbyopia
For m o s t musicians a n d p e r f o r m e r s , vision is a vital aspect o f their art. Vision provides the mediu m t h r o u g h which the ideas o f the c o m p o s e r are translated into p e r f o r m a n c e . As the general p o p ulation grows older, an ever-increasing p r o p o r t i o n o f musicians will e x p e r i e n c e the effects o f a g i n g o n the visual system. O f t e n overlooked by the health care provider are the special n e e d s o f the musician a n d p e r f o r m e r . Musicians work at very specific distances in relation to their instruments a n d music; for instance, trump e t players m a y want their music placed at a distance different f r o m that p r e f e r r e d by French h o r n players. With an ensemble, m a n y different working distances m a y be required, d e p e n d i n g on the perf o r m e r s a n d their instruments. In addition, a musician's visual d e m a n d s are such that he or she m u s t be able to m o n i t o r c o n c u r r e n t l y a c o n d u c t o r ' s cues. A d a p t i o n is easy for the y o u n g musician, b u t for older musicians or for y o u n g e r musicians as they eventually b e c o m e presbyopic, these special visual d e m a n d s b e c o m e difficult to m e e t a n d often c a n n o t be m e t by traditionally prescribed lenses. T h e p u r p o s e o f this article is to briefly review s o m e basic optical principles, apply t h e m to the p r e s b y o p i c musician, a n d f u r t h e r review s o m e o f the modalities available to aid o l d e r musicians in practicing their v i s i o n - d e p e n d e n t art.
A c c o m m o d a t i o n and Its M e a s u r e m e n t A c c o m m o d a t i o n , or a c c o m m o d a t i v e amplitude, can b e calculated by t h r e e m e t h o d s : m e a s u r e m e n t o f the n e a r p o i n t of a c c o m m o d a t i o n , use o f the a c c o m m o d a t i v e rule, a n d application o f the m e t h o d of spheres. T h e simplest practical m e a n s of m e a s u r i n g the n e a r p o i n t o f a c c o m m o d a t i o n is to have the patient fixate o n small p r i n t (e.g., 5-point type) a n d move a test card toward the eye until the p r i n t blurs. This, by d e f n i t i o n , is the n e a r point. I f the eye is emm e t r o p i c or r e n d e r e d e m m e t r o p i c by the p r o p e r refractive correction, the far p o i n t is at infinity a n d the n e a r p o i n t m a y be directly converted into diopters o f a c c o m m o d a t i v e amplitude. T h e second m e t h o d uses the a c c o m m o d a t i v e rule, or Prince rule, which combines a r e a d i n g card with a ruler calibrated in centimeters a n d diopters (D). If o n e places, for example, a +3.00 D lens in f r o n t of an e m m e t r o p i c eye (or an eye r e n d e r e d e m m e t r o p i c by spectacle correction), the far p o i n t is b r o u g h t in to - meter. Similarly, the n e a r p o i n t is b r o u g h t in a c o r r e s p o n d i n g 3 D closer. By subtracting the far p o i n t (in diopters) f r o m the m e a s u r e d n e a r p o i n t (in diopters), o n e can easily obtain the a m p l i t u d e o f a c c o m m o d a t i o n . T h e third m e a n s of m e a s u r i n g a c c o m m o d a t i v e a m p l i t u d e is the m e t h o d o f 338~
© 1996. Survey of Ophthalmology. (7 Kent Street, Brookline, MA 02146. Tel: 617-566-2138. Fax: 617-566-4019)
VISUAL PROBLEMS OF THE AGING MUSICIAN spheres. For this method, the patient fixates o n a n e a r target (e.g., 40 cm). A c c o m m o d a t i o n is stimulated by the p l a c e m e n t o f successively stronger minus spheres until the print blurs. A c c o m m o d a t i o n is then relaxed by use of successively stronger plus spheres until the print blurs again. T h e sum of these two values is a direct measure of the amplitude of accommodation, As implied by the above discussion, accommodative amplitude is properly a m o n o c u l a r expression and is m e a s u r e d for each eye independently. Binocular amplitude generally exceeds the m o n o c u l a r m e a s u r e m e n t by 0.5 to 1.0 D.
C o r r e c t i n g P r e s b y o p i a in the Musician Presbyopia becomes a clinical p r o b l e m when the remaining accommodative amplitude is insufficient for patients to carry out their accustomed visual tasks. T h e onset o f presbyopia depends, in part, o n the patient's age and refractive error, and the type of visual task. T h e onset o f presbyopia is obviously no different for the musician than for anyone else in this age group; however, the visual demands of this profession or avocation may be unique. Many o t h e r visually d e m a n d i n g occupations and hobbies may have similarly u n i q u e problems. H o w can presbyopia in the musician be corrected? First, the musician may be able to move the music f u r t h e r away, b u t this solution has its limitations. Presbyopic individuals with mild myopia (approximately 2 D or less) m a y simply be able to r e m o v e their glasses a n d r e a d the music perfectly. This m e t h o d also has its limitations, because distance visual acuity is c o m p r o m i s e d . Most presbyopic musicians, therefore, require refractive correction. As n o t e d earlier, o n e must take into acc o u n t the individual ~sual d e m a n d s o f each performer. A pianist, for example, requires that the music be p l a c e d somewhat less than 1 m e t e r away. A trombonist, in contrast, often requires that the music be p l a c e d at a distance g r e a t e r than 1 m e t e r to a c c o m m o d a t e the instrument, whereas flutists may p r e f e r a distance s o m e w h e r e in between. To d e t e r m i n e the c o r r e c t power o f the bifocal add required, simple calculations can be perf o r m e d . T h e calculations used are n o different f r o m those n e e d e d for p r o p e r l y prescribing an add for reading, a l t h o u g h we m o r e often than n o t omit these m e a s u r e m e n t s routinely. First, the a c c o m m o d a t i o n r e q u i r e d for the given n e a r visual task should b e d e t e r m i n e d . For an emm e t r o p e (or an individual r e n d e r e d e m m e t r o p i c by refractive c o r r e c t i o n ) , r e a d i n g at 40 cm requires 2.5 D o f a c c o m m o d a t i v e effort. Similarly, for o u r purposes, a music stand placed at 80 cm requires 1.25 D o f a c c o m m o d a t i o n . Second, one-half o f the patient's a c c o m m o d a t i v e amplitude should be h e l d
339 in reserve to allow for comfortable viewing and to p r e v e n t asthenopic symptoms, a l t h o u g h this value may vary considerably from patient to patient? Third, the tentative power o f the add required is, thus, the patient's available a c c o m m o d a t i o n subtracted f r o m the total a c c o m m o d a t i o n r e q u i r e d 133the task. Finally, and most important, there should be a trial with the patient wearing the add to test the accommodative range for the patient's task. Each add has an effective range that. with the patient's own a c c o m m o d a t i o n , should allow for some flexibility in the viewing distance Since successful prescription of bifocal adds for musicians d e p e n d s on attention to their individual needs, they should measure their p r e f e r r e d working distance a n d bring this m e a s u r e m e n t with t h e m to the office. Better yet, musicians may want to bring sheet music, a music stand, a n d instrum e n t to the office for the most accurate simulation o f the musical setting.
Methods of Correction All the traditional m e t h o d s o f correcting for presbyopia also apply to the musmian; however, various spectacles a n d contact lenses may have certain advantages or disadvantages for the musician. Traditional fused bifocals are available in the flat top, r o u n d top, a n d c u r v e d top. Because o f the prismatic effect at the interfaces, the c u r v e d top and the r o u n d top may have considerable imagej u m p , which might be annoying to the musician. T h e one-piece, large, c u r v e d bifocal would similarly p r o d u c e image-jump. T h e flat top is available in a range of segment diameters, the larger o f which may be useful to the musician who needs to scan over the width of a music stand. T h e executive bifocal provides the widest reading segment, a n d is also an excellent choice for some individuals. T h e traditional trifocal theoretically provides all three viewing segments n e e d e d , b u t the small int e r m e d i a t e s e g m e n t can be c u m b e r s o m e . A trifocal with an e x p a n d e d i n t e r m e d i a t e segment, however, may be a useful alternative with its taller segment height o f 9 o r 11 mm, providing a larger "window" t h r o u g h which the musician can scan a page of music (Fig. 1). T h e progressive trifocal lens is a n o t h e r alternative, b u t because of a b e r r a t i o n in the p e r i p h e r y o f the i n t e r m e d i a t e viewing area, often only a narrow c o r r i d o r o f clear viewing is provided. This may be annoying to the musicaan who needs to scan a h e a d in a piece o f music with the eyes r a t h e r than using h e a d movements. Recently, a new g e n e r a t i o n o f progressive lens has b e e n introduced, which may partially solve this problem. This lens p r o d u c e s less
340
Surv Ophthalmol 40 (4) January-February 1996
KADRMAS ET AL
71 m m
2 mm
1
t 11 m m
Fig. 2. Executive-style bifocal spectacles with distance (D) segment on top and intermediate (I) distance viewing segment on the bottom.
(-----28
mm -~.
Fig. 1. Trifocal spectacles demonstrating expanded intermediate segment (shaded).
a b e r r a t i o n in the periphery, a n d provides an imp r o v e d trifocal effect. Sometimes special prescriptions, or "music glasses," are r e q u i r e d for musicians. In effect, these are the m o d i f i e d bifocals m e n t i o n e d previously. If only clear distance vision and i n t e r m e d i a t e vision are required, such as for an instrumentalist in an orchestra, spectacles with a distance segment on top and an i n t e r m e d i a t e viewing s e g m e n t o n the bottom may suffice (Fig. 2). If, o n the o t h e r hand, the musician, a solo pianist for example, does not necessarily n e e d to see a conductor, spectacles with an i n t e r m e d i a t e viewing s e g m e n t o n top to enable the reading of music a n d with a n e a r segment on the b o t t o m to facilitate n o r m a l r e a d i n g may be what is n e e d e d (Fig. 3). (These same spectacles may be useful to the c o m p u t e r user.) Creativity in the construction o f spectacles for musicians is often required. A presbyopic harpist o n c e b e n e f i t e d f r o m the thoughtful ingenuity o f h e r ophthalmologist, who devised the spectacles
Fig. 3. Executive-style bifocal spectacles with intermediate (I) distance viewing segment on top and near (N) segment on the bottom.
depicted in Fig. 4. This presbyopic musician req u i r e d the u p p e r right segment to view the strings o f h e r i n s t r u m e n t and the lower left segment to view h e r music. She was quite pleased with the result. Similarly constructed spectacles with an u p p e r right i n t e r m e d i a t e segment a n d a lower left n e a r segment may be useful to a presbyopic, right-handed violinist. Musicians are often c o n c e r n e d a b o u t cosmetic appearance, and spectacles can i n d e e d be somewhat c u m b e r s o m e for performers. Contact lenses are t h e r e f o r e an i m p o r t a n t consideration for some presbyopic musicians. M a n a g e m e n t o f presbyopia with contact lenses takes several forms. Bifocal contact lenses are available in basically three categories: the alternating vision design, the simultaneous vision design, and the progressive, or continuously variable, design. T h e alternating vision design (or s e g m e n t e d bifocal contact lens) is based on a c o n c e p t similar to that o f the s e g m e n t e d bifocal spectacle, with the top p o r t i o n o f the lens used for distance and the b o t t o m p o r t i o n for n e a r viewing. T h e s e lenses (available in rigid gas-permeable f o r m ) generally r e m a i n c e n t e r e d because of t r u n c a t i o n o f the lens
Fig. 4. Presbyopic "harpist's glasses" (right-handed) with upper right segment for near (N) viewing and lower left segment for intermediate (I) distance viewing.
VISUAL PROBLEMS OF THE AGING MUSICIAN to rest o n the lower eyelid c o m b i n e d with a p r i s m ballast to h e l p p r e v e n t rotation. T h e simultaneous vision, or annular, design is available in soft lens or rigid gas-permeable form. This lens is designed with a central distance p o r t i o n s u r r o u n d e d by an a n n u l a r n e a r s e g m e n t or vice versa. W h e n the eye gazes at a distant object, bundles of light rays f r o m that object simultaneously pass t h r o u g h b o t h the distance a n d the n e a r portions o f the lens. T h e rays that pass t h r o u g h the distance p o r t i o n o f the lens f o r m a clear focus on the macula. T h e rays that pass t h r o u g h the n e a r p o r t i o n f o r m a diffusion circle o n the macula; thus, a b l u r r e d i m a g e is s u p e r i m p o s e d o n the clear image. T h e diffusion circle causes the p a t i e n t looking at a Snellen chart, to observe a " s h a d o w " a r o u n d the letters. I f gaze is directed at a n e a r object, the opposite occurs. In either instance, w h e t h e r gaze is directed at a n e a r or distant object, the individual learns to c o n c e n t r a t e on the clear i m a g e a n d ignore the b l u r r e d one. However, each i m a g e is n o t perfectly clear a n d represents a c o m p r o m i s e that m a y suffice for the individual's needs. Taking this o n e step f u r t h e r is the progressive, or c o n t i n u o u s l y variable, c o n t a c t lens, which has a central distance optical z o n e ~ t h progressively increasing p o w e r radiating outward in c o n c e n t r i c circles. For any given distance, the individual learns to c o n c e n t r a t e o n the clear i m a g e a n d i g n o r e the b l u r r e d ones, b u t again this is a c o m p r o m i s e in clear vision at any o n e distance. Surprisingly, m a n y p r e s b y o p i c p e r s o n s who wear c o n t a c t lenses s e e m to a d a p t quickly a n d enjoy the flexibility this lens gives t h e m , b u t this result is highly d e p e n d e n t Oil the individual. Lastly, the c o n c e p t o f m o n o v i s i o n is an i m p o r tant, i f n o t the m o s t i m p o r t a n t , alternative f o r the p r e s b y o p i c musician who desires to wear contact lenses. C o r r e c t i n g the d o m i n a n t eye for distance a n d the o t h e r for n e a r or i n t e r m e d i a t e vision is surprisingly well-tolerated by m a n y individuals, a n d is m o s t often the p r e f e r r e d m e t h o d for the presbyopic c o n t a c t lens wearer. Ultimately, the choice of corrective lenses d e p e n d s o n the individual's specific visual d e m a n d s a n d p r e f e r e n c e .
341 tion to p r o p e r p r e s c r i p t i o n of the bifocal add. 2 A g o o d rule of t h u m b is that for a given a m o u n t of m i n u s p o w e r a d d e d to the distance correction, app r o x i m a t e l y o n e - h a l f of that s h o u l d be a d d e d b a c k to the n e a r s e g m e n t . In addition, g o o d lighting is of considerable i m p o r t a n c e , a n d cataract extraction m a y eventually be required. Age-related m a c u l a r d e g e n e r a t i o n can also steal vision away, resuIting in a central s c o t o m a or met a m o r p h o p s i a that necessitates the use of low-vision aids to increase axial magnification. T h e possibility o f a Valsalva m a n e u v e r (involved in playing m o s t wind instruments) invoking h e m o r r h a g e f r o m a preexisting subretinal neovascular m e m b r a n e or f r o m neovascularization associated with proliferative diabetic r e t i n o p a t h y is at least theoretically possible. However, we k n o w of n o reports o f this type o f h e m o r r h a g e in musicians.
E n v i r o n m e n t a l Lighting E n v i r o n m e n t a l lighting is o f considerable imp o r t a n c e to the p e r f o r m i n g musician. Most places o f p e r f o r m a n c e are illuminated by f l u o r e s c e n t lights, which can cause a n n o y i n g glare. F l u o r e s c e n t light has a g r e a t e r a m o u n t o f s h o r t e r wavelength l i g h t - - t o w a r d the blue e n d o f the s p e c t r u m - - t h a n i n c a n d e s c e n t light. T h e s e s h o r t e r wavelengths are responsible for m u c h o f the glare. Glare can be alleviated to s o m e e x t e n t by a soft tint, such as cali c h r o m e yellow, or by antireflective coating o n spectacle lenses. Also. yellow p a p e r (or old sheet music) tends to reflect less o f the s h o r t e r wavelength light a n d p r o d u c e s less glare. Summary We have reviewed the visual needs o f the music i a n - p e r f o r m e r a n d discussed how these needs can be m e t by prescribing a p p r o p r i a t e corrective lenses. By paying close attention to the special visual dem a n d s of each individual, no m a t t e r what the vocation or avocation, the o p h t h a l m o l o g i s t can provide a satisfactory solution to what can be a frustrating p r o b l e m for the patient with presbyopia.
References
Other Age-related Ocular Conditions
1. Milder B' and Rubin ML: T h e Fine Art ° f Prescribing Glasses" Triad, Gainesville, FL, 1991. 121 2. Rubin ML: The case of the "'myopic capitalist." Surv O p h t h a l m o l 13:122-123. 1968
Several o t h e r age-related eye changes can obviously have an effect o n musicians, the m o s t comm o n b e i n g cataract. In addition to p r o d u c i n g glare a n d s o m e a b e r r a t i o n , a cataract (primarily n u c l e a r sclerosis) induces a lenticular m y o p i c shift. A meticulous refraction is i m p o r t a n t , with special atten-
This report was s u p p o r t e d in parl by an unrestricted grant from Research to Prevent Blindness. New York, New York. and by the Mayo Foundation, Rochesmr. Minnesota. T h e authors have n o proprietary interest in any of the products m e n t i o n e d in the article. Reprints are not available.
PERSPECTIVES IN REFRACTION MELVIN L. RUBIN, EDITOR
Visual Problems of the Aging Musician EDDIE F. KADRMAS, MD, PHD, JOHN A. DYER, MD, AND GEORGE B. BARTLEY, MD
Department of Ophthalmology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA Abstract. The presbyopic musician presents the ophthalmologist with an often demanding set of visual needs. Many modalities, some necessarily creative, are available to aid older musicians in their vision-dependent art. (Surv Ophthalmol 40:338-341, 1996)
Key words, musician
•
presbyopia
For m o s t musicians a n d p e r f o r m e r s , vision is a vital aspect o f their art. Vision provides the mediu m t h r o u g h which the ideas o f the c o m p o s e r are translated into p e r f o r m a n c e . As the general p o p ulation grows older, an ever-increasing p r o p o r t i o n o f musicians will e x p e r i e n c e the effects o f a g i n g o n the visual system. O f t e n overlooked by the health care provider are the special n e e d s o f the musician a n d p e r f o r m e r . Musicians work at very specific distances in relation to their instruments a n d music; for instance, trump e t players m a y want their music placed at a distance different f r o m that p r e f e r r e d by French h o r n players. With an ensemble, m a n y different working distances m a y be required, d e p e n d i n g on the perf o r m e r s a n d their instruments. In addition, a musician's visual d e m a n d s are such that he or she m u s t be able to m o n i t o r c o n c u r r e n t l y a c o n d u c t o r ' s cues. A d a p t i o n is easy for the y o u n g musician, b u t for older musicians or for y o u n g e r musicians as they eventually b e c o m e presbyopic, these special visual d e m a n d s b e c o m e difficult to m e e t a n d often c a n n o t be m e t by traditionally prescribed lenses. T h e p u r p o s e o f this article is to briefly review s o m e basic optical principles, apply t h e m to the p r e s b y o p i c musician, a n d f u r t h e r review s o m e o f the modalities available to aid o l d e r musicians in practicing their v i s i o n - d e p e n d e n t art.
A c c o m m o d a t i o n and Its M e a s u r e m e n t A c c o m m o d a t i o n , or a c c o m m o d a t i v e amplitude, can b e calculated by t h r e e m e t h o d s : m e a s u r e m e n t o f the n e a r p o i n t of a c c o m m o d a t i o n , use o f the a c c o m m o d a t i v e rule, a n d application o f the m e t h o d of spheres. T h e simplest practical m e a n s of m e a s u r i n g the n e a r p o i n t o f a c c o m m o d a t i o n is to have the patient fixate o n small p r i n t (e.g., 5-point type) a n d move a test card toward the eye until the p r i n t blurs. This, by d e f n i t i o n , is the n e a r point. I f the eye is emm e t r o p i c or r e n d e r e d e m m e t r o p i c by the p r o p e r refractive correction, the far p o i n t is at infinity a n d the n e a r p o i n t m a y be directly converted into diopters o f a c c o m m o d a t i v e amplitude. T h e second m e t h o d uses the a c c o m m o d a t i v e rule, or Prince rule, which combines a r e a d i n g card with a ruler calibrated in centimeters a n d diopters (D). If o n e places, for example, a +3.00 D lens in f r o n t of an e m m e t r o p i c eye (or an eye r e n d e r e d e m m e t r o p i c by spectacle correction), the far p o i n t is b r o u g h t in to - meter. Similarly, the n e a r p o i n t is b r o u g h t in a c o r r e s p o n d i n g 3 D closer. By subtracting the far p o i n t (in diopters) f r o m the m e a s u r e d n e a r p o i n t (in diopters), o n e can easily obtain the a m p l i t u d e o f a c c o m m o d a t i o n . T h e third m e a n s of m e a s u r i n g a c c o m m o d a t i v e a m p l i t u d e is the m e t h o d o f 338~
© 1996. Survey of Ophthalmology. (7 Kent Street, Brookline, MA 02146. Tel: 617-566-2138. Fax: 617-566-4019)
VISUAL PROBLEMS OF THE AGING MUSICIAN spheres. For this method, the patient fixates o n a n e a r target (e.g., 40 cm). A c c o m m o d a t i o n is stimulated by the p l a c e m e n t o f successively stronger minus spheres until the print blurs. A c c o m m o d a t i o n is then relaxed by use of successively stronger plus spheres until the print blurs again. T h e sum of these two values is a direct measure of the amplitude of accommodation, As implied by the above discussion, accommodative amplitude is properly a m o n o c u l a r expression and is m e a s u r e d for each eye independently. Binocular amplitude generally exceeds the m o n o c u l a r m e a s u r e m e n t by 0.5 to 1.0 D.
C o r r e c t i n g P r e s b y o p i a in the Musician Presbyopia becomes a clinical p r o b l e m when the remaining accommodative amplitude is insufficient for patients to carry out their accustomed visual tasks. T h e onset o f presbyopia depends, in part, o n the patient's age and refractive error, and the type of visual task. T h e onset o f presbyopia is obviously no different for the musician than for anyone else in this age group; however, the visual demands of this profession or avocation may be unique. Many o t h e r visually d e m a n d i n g occupations and hobbies may have similarly u n i q u e problems. H o w can presbyopia in the musician be corrected? First, the musician may be able to move the music f u r t h e r away, b u t this solution has its limitations. Presbyopic individuals with mild myopia (approximately 2 D or less) m a y simply be able to r e m o v e their glasses a n d r e a d the music perfectly. This m e t h o d also has its limitations, because distance visual acuity is c o m p r o m i s e d . Most presbyopic musicians, therefore, require refractive correction. As n o t e d earlier, o n e must take into acc o u n t the individual ~sual d e m a n d s o f each performer. A pianist, for example, requires that the music be p l a c e d somewhat less than 1 m e t e r away. A trombonist, in contrast, often requires that the music be p l a c e d at a distance g r e a t e r than 1 m e t e r to a c c o m m o d a t e the instrument, whereas flutists may p r e f e r a distance s o m e w h e r e in between. To d e t e r m i n e the c o r r e c t power o f the bifocal add required, simple calculations can be perf o r m e d . T h e calculations used are n o different f r o m those n e e d e d for p r o p e r l y prescribing an add for reading, a l t h o u g h we m o r e often than n o t omit these m e a s u r e m e n t s routinely. First, the a c c o m m o d a t i o n r e q u i r e d for the given n e a r visual task should b e d e t e r m i n e d . For an emm e t r o p e (or an individual r e n d e r e d e m m e t r o p i c by refractive c o r r e c t i o n ) , r e a d i n g at 40 cm requires 2.5 D o f a c c o m m o d a t i v e effort. Similarly, for o u r purposes, a music stand placed at 80 cm requires 1.25 D o f a c c o m m o d a t i o n . Second, one-half o f the patient's a c c o m m o d a t i v e amplitude should be h e l d
339 in reserve to allow for comfortable viewing and to p r e v e n t asthenopic symptoms, a l t h o u g h this value may vary considerably from patient to patient? Third, the tentative power o f the add required is, thus, the patient's available a c c o m m o d a t i o n subtracted f r o m the total a c c o m m o d a t i o n r e q u i r e d 133the task. Finally, and most important, there should be a trial with the patient wearing the add to test the accommodative range for the patient's task. Each add has an effective range that. with the patient's own a c c o m m o d a t i o n , should allow for some flexibility in the viewing distance Since successful prescription of bifocal adds for musicians d e p e n d s on attention to their individual needs, they should measure their p r e f e r r e d working distance a n d bring this m e a s u r e m e n t with t h e m to the office. Better yet, musicians may want to bring sheet music, a music stand, a n d instrum e n t to the office for the most accurate simulation o f the musical setting.
Methods of Correction All the traditional m e t h o d s o f correcting for presbyopia also apply to the musmian; however, various spectacles a n d contact lenses may have certain advantages or disadvantages for the musician. Traditional fused bifocals are available in the flat top, r o u n d top, a n d c u r v e d top. Because o f the prismatic effect at the interfaces, the c u r v e d top and the r o u n d top may have considerable imagej u m p , which might be annoying to the musician. T h e one-piece, large, c u r v e d bifocal would similarly p r o d u c e image-jump. T h e flat top is available in a range of segment diameters, the larger o f which may be useful to the musician who needs to scan over the width of a music stand. T h e executive bifocal provides the widest reading segment, a n d is also an excellent choice for some individuals. T h e traditional trifocal theoretically provides all three viewing segments n e e d e d , b u t the small int e r m e d i a t e s e g m e n t can be c u m b e r s o m e . A trifocal with an e x p a n d e d i n t e r m e d i a t e segment, however, may be a useful alternative with its taller segment height o f 9 o r 11 mm, providing a larger "window" t h r o u g h which the musician can scan a page of music (Fig. 1). T h e progressive trifocal lens is a n o t h e r alternative, b u t because of a b e r r a t i o n in the p e r i p h e r y o f the i n t e r m e d i a t e viewing area, often only a narrow c o r r i d o r o f clear viewing is provided. This may be annoying to the musicaan who needs to scan a h e a d in a piece o f music with the eyes r a t h e r than using h e a d movements. Recently, a new g e n e r a t i o n o f progressive lens has b e e n introduced, which may partially solve this problem. This lens p r o d u c e s less
340
Surv Ophthalmol 40 (4) January-February 1996
KADRMAS ET AL
71 m m
2 mm
1
t 11 m m
Fig. 2. Executive-style bifocal spectacles with distance (D) segment on top and intermediate (I) distance viewing segment on the bottom.
(-----28
mm -~.
Fig. 1. Trifocal spectacles demonstrating expanded intermediate segment (shaded).
a b e r r a t i o n in the periphery, a n d provides an imp r o v e d trifocal effect. Sometimes special prescriptions, or "music glasses," are r e q u i r e d for musicians. In effect, these are the m o d i f i e d bifocals m e n t i o n e d previously. If only clear distance vision and i n t e r m e d i a t e vision are required, such as for an instrumentalist in an orchestra, spectacles with a distance segment on top and an i n t e r m e d i a t e viewing s e g m e n t o n the bottom may suffice (Fig. 2). If, o n the o t h e r hand, the musician, a solo pianist for example, does not necessarily n e e d to see a conductor, spectacles with an i n t e r m e d i a t e viewing s e g m e n t o n top to enable the reading of music a n d with a n e a r segment on the b o t t o m to facilitate n o r m a l r e a d i n g may be what is n e e d e d (Fig. 3). (These same spectacles may be useful to the c o m p u t e r user.) Creativity in the construction o f spectacles for musicians is often required. A presbyopic harpist o n c e b e n e f i t e d f r o m the thoughtful ingenuity o f h e r ophthalmologist, who devised the spectacles
Fig. 3. Executive-style bifocal spectacles with intermediate (I) distance viewing segment on top and near (N) segment on the bottom.
depicted in Fig. 4. This presbyopic musician req u i r e d the u p p e r right segment to view the strings o f h e r i n s t r u m e n t and the lower left segment to view h e r music. She was quite pleased with the result. Similarly constructed spectacles with an u p p e r right i n t e r m e d i a t e segment a n d a lower left n e a r segment may be useful to a presbyopic, right-handed violinist. Musicians are often c o n c e r n e d a b o u t cosmetic appearance, and spectacles can i n d e e d be somewhat c u m b e r s o m e for performers. Contact lenses are t h e r e f o r e an i m p o r t a n t consideration for some presbyopic musicians. M a n a g e m e n t o f presbyopia with contact lenses takes several forms. Bifocal contact lenses are available in basically three categories: the alternating vision design, the simultaneous vision design, and the progressive, or continuously variable, design. T h e alternating vision design (or s e g m e n t e d bifocal contact lens) is based on a c o n c e p t similar to that o f the s e g m e n t e d bifocal spectacle, with the top p o r t i o n o f the lens used for distance and the b o t t o m p o r t i o n for n e a r viewing. T h e s e lenses (available in rigid gas-permeable f o r m ) generally r e m a i n c e n t e r e d because of t r u n c a t i o n o f the lens
Fig. 4. Presbyopic "harpist's glasses" (right-handed) with upper right segment for near (N) viewing and lower left segment for intermediate (I) distance viewing.
VISUAL PROBLEMS OF THE AGING MUSICIAN to rest o n the lower eyelid c o m b i n e d with a p r i s m ballast to h e l p p r e v e n t rotation. T h e simultaneous vision, or annular, design is available in soft lens or rigid gas-permeable form. This lens is designed with a central distance p o r t i o n s u r r o u n d e d by an a n n u l a r n e a r s e g m e n t or vice versa. W h e n the eye gazes at a distant object, bundles of light rays f r o m that object simultaneously pass t h r o u g h b o t h the distance a n d the n e a r portions o f the lens. T h e rays that pass t h r o u g h the distance p o r t i o n o f the lens f o r m a clear focus on the macula. T h e rays that pass t h r o u g h the n e a r p o r t i o n f o r m a diffusion circle o n the macula; thus, a b l u r r e d i m a g e is s u p e r i m p o s e d o n the clear image. T h e diffusion circle causes the p a t i e n t looking at a Snellen chart, to observe a " s h a d o w " a r o u n d the letters. I f gaze is directed at a n e a r object, the opposite occurs. In either instance, w h e t h e r gaze is directed at a n e a r or distant object, the individual learns to c o n c e n t r a t e on the clear i m a g e a n d ignore the b l u r r e d one. However, each i m a g e is n o t perfectly clear a n d represents a c o m p r o m i s e that m a y suffice for the individual's needs. Taking this o n e step f u r t h e r is the progressive, or c o n t i n u o u s l y variable, c o n t a c t lens, which has a central distance optical z o n e ~ t h progressively increasing p o w e r radiating outward in c o n c e n t r i c circles. For any given distance, the individual learns to c o n c e n t r a t e o n the clear i m a g e a n d i g n o r e the b l u r r e d ones, b u t again this is a c o m p r o m i s e in clear vision at any o n e distance. Surprisingly, m a n y p r e s b y o p i c p e r s o n s who wear c o n t a c t lenses s e e m to a d a p t quickly a n d enjoy the flexibility this lens gives t h e m , b u t this result is highly d e p e n d e n t Oil the individual. Lastly, the c o n c e p t o f m o n o v i s i o n is an i m p o r tant, i f n o t the m o s t i m p o r t a n t , alternative f o r the p r e s b y o p i c musician who desires to wear contact lenses. C o r r e c t i n g the d o m i n a n t eye for distance a n d the o t h e r for n e a r or i n t e r m e d i a t e vision is surprisingly well-tolerated by m a n y individuals, a n d is m o s t often the p r e f e r r e d m e t h o d for the presbyopic c o n t a c t lens wearer. Ultimately, the choice of corrective lenses d e p e n d s o n the individual's specific visual d e m a n d s a n d p r e f e r e n c e .
341 tion to p r o p e r p r e s c r i p t i o n of the bifocal add. 2 A g o o d rule of t h u m b is that for a given a m o u n t of m i n u s p o w e r a d d e d to the distance correction, app r o x i m a t e l y o n e - h a l f of that s h o u l d be a d d e d b a c k to the n e a r s e g m e n t . In addition, g o o d lighting is of considerable i m p o r t a n c e , a n d cataract extraction m a y eventually be required. Age-related m a c u l a r d e g e n e r a t i o n can also steal vision away, resuIting in a central s c o t o m a or met a m o r p h o p s i a that necessitates the use of low-vision aids to increase axial magnification. T h e possibility o f a Valsalva m a n e u v e r (involved in playing m o s t wind instruments) invoking h e m o r r h a g e f r o m a preexisting subretinal neovascular m e m b r a n e or f r o m neovascularization associated with proliferative diabetic r e t i n o p a t h y is at least theoretically possible. However, we k n o w of n o reports o f this type o f h e m o r r h a g e in musicians.
E n v i r o n m e n t a l Lighting E n v i r o n m e n t a l lighting is o f considerable imp o r t a n c e to the p e r f o r m i n g musician. Most places o f p e r f o r m a n c e are illuminated by f l u o r e s c e n t lights, which can cause a n n o y i n g glare. F l u o r e s c e n t light has a g r e a t e r a m o u n t o f s h o r t e r wavelength l i g h t - - t o w a r d the blue e n d o f the s p e c t r u m - - t h a n i n c a n d e s c e n t light. T h e s e s h o r t e r wavelengths are responsible for m u c h o f the glare. Glare can be alleviated to s o m e e x t e n t by a soft tint, such as cali c h r o m e yellow, or by antireflective coating o n spectacle lenses. Also. yellow p a p e r (or old sheet music) tends to reflect less o f the s h o r t e r wavelength light a n d p r o d u c e s less glare. Summary We have reviewed the visual needs o f the music i a n - p e r f o r m e r a n d discussed how these needs can be m e t by prescribing a p p r o p r i a t e corrective lenses. By paying close attention to the special visual dem a n d s of each individual, no m a t t e r what the vocation or avocation, the o p h t h a l m o l o g i s t can provide a satisfactory solution to what can be a frustrating p r o b l e m for the patient with presbyopia.
References
Other Age-related Ocular Conditions
1. Milder B' and Rubin ML: T h e Fine Art ° f Prescribing Glasses" Triad, Gainesville, FL, 1991. 121 2. Rubin ML: The case of the "'myopic capitalist." Surv O p h t h a l m o l 13:122-123. 1968
Several o t h e r age-related eye changes can obviously have an effect o n musicians, the m o s t comm o n b e i n g cataract. In addition to p r o d u c i n g glare a n d s o m e a b e r r a t i o n , a cataract (primarily n u c l e a r sclerosis) induces a lenticular m y o p i c shift. A meticulous refraction is i m p o r t a n t , with special atten-
This report was s u p p o r t e d in parl by an unrestricted grant from Research to Prevent Blindness. New York, New York. and by the Mayo Foundation, Rochesmr. Minnesota. T h e authors have n o proprietary interest in any of the products m e n t i o n e d in the article. Reprints are not available.