Nonsurgical Treatment of Neurologic Diplopia Eric L. Singman M.D., Ph.D.1 Noelle S. Matta C.O., C.R.C., C.O.T.2 David I. Silbert M.D., F.A.A.P. 2
ABSTRACT The ocular motor pathways are complex and disorders of these pathways can be devastating for patients, in some cases leading to loss of employment and independence. Surgical intervention for these cases is not always warranted, possible, or even safe for some patients, and nonsurgical and orthoptic treatments can provide significant relief. This paper will discuss various treatment options, including eye exercises, prisms, optical manipulation, occlusion, and lifestyle changes.
INTRODUCTION The ocular motor pathways are complex. Disorders of these pathways can be devastating for patients, in some cases leading to loss of employment and independence. Surgical intervention for these cases is not always warranted, possible, or even safe for some patients, and nonsurgical and orFrom the 1Wilmer Eye Institute, Baltimore, Maryland, and the 2Family Eye Group, Lancaster, Pennsylvania. Reprint requests should be addressed to: Noelle S. Matta C.O., C.R.C., C.O.T., Family Eye Group, 2110 Harrisburg Pike, Ste. 215, Lancaster, PA 17601; e-mail: NoelleMatta@ gmail.com Presented in part at the International Strabismological Association (ISA) symposium on Eye Movement Disorders at the XII International Orthoptic Congress, Toronto, Canada, June 26-29, 2012.
thoptic treatments can provide significant relief. According to a survey of 140 adult patients with strabismus, the diplopia can be so problematic that 60% of them would be willing to trade part of their life expectancy in return for being rid of the problem.1 Depending on the cause of diplopia, treatment options include nonsurgical as well as surgical approaches. In this review, we will discuss the nonsurgical treatments for neurologic diplopia, including eye exercises, prisms, optical manipulation, occlusion, and lifestyle changes. The goal of treatment is to allow the patient to recover a premorbid quality of life and functioning. A trip to the orthoptist may allow patients to regain their independence and to be able to return to work.
© 2013 Board of Regents of the University of Wisconsin System, American Orthoptic Journal, Volume 63, 2013, ISSN 0065-955X, E-ISSN 1553-4448
American Orthoptic Journal
63
DIPLOPIA TREATMENT
NEUROLOGIC AND MECHANICAL DIPLOPIA Diplopia can arise from mechanical or neurologic etiologies. Mechanical causes of diplopia stem from trauma to the extraocular musculature (EOM), their tendons or the bony orbit to which they are attached, as well as from infectious, inflammatory, or neoplastic diseases of those tissues, and also from dystrophic diseases of the muscles. Restrictive strabismus can occur when the muscles are inflamed or infiltrated, as in Graves’ ophthalmopathy, or when eye muscles are dystrophic, as in the mitochondrial myopathy of chronic progressive external ophthalmoplegia. These disorders can also lead to a paralytic strabismus. Neurologic causes of diplopia stem from similar disease states affecting the nerves innervating the EOM). These diseases might affect the nerve-muscle synapse (e.g., myasthenia gravis), the axons or cranial ganglia (e.g., vaso- occlusive disease, aneurysm), as well as the supranuclear control centers of eye movement (e.g., intracranial hypertension). It should be noted that the dichotomy between neurologic and mechanical diplopia is not absolute; neurologic diplopia can lead to atrophy of denervated muscles, and secondary hypertrophy of yoked or antagonist muscles, which adds a mechanical component to the strabismus.2 THE ORTHOPTIC EXAMINATION The orthoptist can measure many facets of a patient’s visual function, including: • Measurement of strabismus in various positions of gaze (by sensorimotor exam and/or Lancaster/Hess chart) • Best-corrected visual acuity (distance and near) • Visual function in preverbal and nonverbal patients
64
• Extraocular motility including versions and ductions • Stereopsis (distance and near) • Pursuit movements • Saccade movements • Accommodative amplitudes • Convergence/divergence amplitudes (horizontal and vertical) • Field of binocular single vision • Evaluation for the presence of phorias/tropias • Evaluation of nystagmus • Torsional abilities including evaluating for the presence of torsional strabismus • Evaluation of retinal correspondence • Evaluation of suppression and measurements of suppression scotoma • Evaluation of proptosis and hypo/ hyper globus • Measurements of eyelids and eyelid function • Evaluation of a patient’s old photos to look for onset/progression of disease • Evaluation of pupil function However, it is also important that the exam includes a careful assessment of the patient’s visual needs. It is helpful for a patient to create a prioritized list of things with which they are struggling. The patient has to understand that each issue may require a separate appointment and separate treatment because many conditions cannot simply be treated with one pair of glasses or a set of exercises. Visual needs can be divided into six categories. These include near, intermediate, and far distance work, and each one has requirements for either short or long duration. The Table provides some common tasks that fit into these categories, although it should be remembered that many tasks could be appropriate for more than one category. Once a patient shares their priorities, the orthoptist should help them set realistic expectations. Patients must be
Volume 63, 2013
SINGMAN
TABLE SAMPLING OF VISUAL TASKS AT DIFFERENT DISTANCES AND DURATIONS Visual Tasks
Short Duration
Long Duration
Near
• • • • • • • • • • • •
• • • • • • • • • • •
Intermediate
Far
Reading a medicine bottle Reading a telephone book Looking at a mobile phone Writing a check Card and board games Eating a meal Cooking Looking at prices at the grocery store Casual sightseeing Glancing at road signs Golf Glancing at a clock or a person walking into a room
Reading a book Reading a newspaper Writing a letter Sewing/knitting Using a computer Reading music Operating machinery Playing video games on a TV Driving a vehicle Watching a movie Watching a live sporting event
guided to understand that the efferent visual pathways are often far too complex to be improved with one treatment. Furthermore, although multiple aids may be provided, the patient may not recover all the functions they enjoyed in the premorbid state. Finally, a patient’s ability to regain fused vision in primary gaze may not translate into a full field of single binocular vision.
tattooing to block light from entering the pupil has been successfully attempted in Spain.4 Another avenue of research is the direct electrical stimulation of the extraocular muscles, with the eventual goal of creating an implantable prosthesis to reanimate a denervated eye muscle.5
MEDICAL AND SURGICAL THERAPIES FOR DIPLOPIA
Nonsurgical therapies work to help the patient either ignore or fuse diplopic images while carrying a lower risk of morbidity.
Medical therapies for diplopia can help patients achieve fusion by altering the strength (weakening or strengthening) of the EOMs through systemically provided or locally injected medications so that they can position the eyes to fixate upon a common point. Surgical therapies for diplopia involve manipulating the insertions or functional lengths of the EOMs to change the power they exert in their respective ranges of motion. A novel surgical approach of implanting an opaque intraocular lens in one eye to effectively render a patient monocular has been explored in England to treat patients with intractable diplopia, but this procedure is not performed in the United States.3 A new procedure involving intrastromal corneal
American Orthoptic Journal
NONSURGICAL THERAPIES AVAILABLE FOR DIPLOPIA
Monocularity Occluding either eye will effectively eliminate diplopia. For acutely ill patients, this is a safe and readily available technique. Elastic patches are often provided for this purpose, but these become soiled quickly and can lead to infection. In addition, occluding all vision to the patient’s eye reduces peripheral vision and peripheral fusion. Preferably, transparent tape covering the optical center and approximately half the surface area of one lens of a patient’s spectacles should be provided.6 If patients do not normally wear eyeglasses, nonprescription sunglasses
65
DIPLOPIA TREATMENT
or over-the-counter bifocals with a plano distance portion can be used. In patients who suffer diplopia in a particular field of gaze but can fuse in primary position, such as those with Brown syndrome, monocular occlusion of the appropriate sector of their eyeglasses can be helpful.7 If it becomes clear that a patient’s diplopia will be intractable, long-term options should be considered. For example, occlusive or tinted contact lenses can be made for those patients who do not wear spectacles.8 Diplopia can also be eliminated through monocular means without occlusion. For example, patients can be fitted with monovision eyeglasses9 or contact lenses.10 In addition, a prism can be used to increase the separation of diplopic images by purposefully over-correcting the angle of deviation, and this approach can make it easier for the patient to ignore the second image.
the “pencil push-ups” that are often prescribed for convergence insufficiency, although effective when performed properly, can now be replaced with computerized orthoptic programs available for home use. 12 Office- based exercise programs, such as those utilizing the synoptophore, may be preferred for patients who need a more structured environment for learning.13 Other low-tech options include the accommodation-convergence bar,14 pen or dot convergence therapy, prism vergence exercises to build fusional vergence amplitudes,15 stereograms, the Brock string, and the three-dot card. It should be noted that external, electrical stimulation of the extraocular muscles has been reported in Russian literature for the treatment of strabismus,16 but there is scant literature written in English concerning this topic.
Orthoptic Exercises
Prisms
Consistent with other muscle systems in the body, the EOM system responds to stimulation with growth and to disuse with atrophy. For example, in patients with chronic superior oblique palsy, the paretic muscle may become atrophic while the contralesional superior rectus can become hypertrophic.2 This hypertrophy might be secondary to the excess innervation to compensate for the relative hypotropia of the eye with the intact superior oblique. The mechanism by which stimulation leads to more robust muscle activity may be due in part to the release of trophic factors.11 Use-enhanced muscle function is the basis for offering orthoptic exercises to patients. Patients with diplopia, particularly those that can still fuse but experience intermittent heterotropias secondary to reduced vergences (horizontal and vertical), often respond very well to exercises. Patients need to be highly motivated for these exercises to be effective. Fortunately,
Prism therapy can reliably establish single binocular vision in at least one field of gaze.17, 18 Fresnel prisms can be applied to a patient’s eyeglasses, and methods have been described wherein a single, obliquely oriented prism can even compensate for both horizontal and vertical diplopia19 or even for a torsional component.20 Patients will sometimes recognize that field of single binocular vision is much smaller than before. Because the eyes converge with near work and diverge with distance vision, a patient can sometimes require different prism corrections in their glasses for different visual tasks, which may lead to the need for separate pairs of glasses. These may contain different prescriptions and prism amounts, or else ground-in prism with a Fresnel in the top of the lens or in the bifocal segment. Prism that is ground into a lens has the advantages over Fresnel prism applied to a lens in that it will give a clearer image, will be easier to clean, and will not fall off.
66
Volume 63, 2013
SINGMAN
However, they are more expensive and increase lens weight and thickness, depending on the power. In addition, it is much more difficult to grind different prism power into the distance and reading portions of the same lens. Fresnel prisms allow the flexibility of easily altering prism power as a patient’s condition improves or worsens.21 Medical Nonsurgical Therapies Some medical nonsurgical therapies are beyond the scope of orthoptists but deserve mention, since it is likely that orthoptists will encounter patients who might benefit from these treatments. Anticholinesterases (e.g., pyridostigmine) and/or steroids (e.g., prednisone) are systemically administered for the treatment of myasthenia gravis. Recent research suggests that prednisone may be more effective than pyridostigmine for treating the diplopia associated with myasthenia gravis.22 Other medical nonsurgical therapies available for ocular myasthenia gravis include plasmapheresis, intravenous immunoglobulin and immunosuppressive agents.23 Anticholinesterases administered topically (phospholine iodide) have been used in the past to treat esotropia secondary to surgical over-correction of exotropia.24 This eye drop was sometimes used as an adjunctive therapy for accommodative esotropia, but it is rarely used for this condition anymore.25 Minimally Invasive Therapies Botulinum toxin injection for chemically denervating (i.e., weakening) muscles with relatively insufficient opposition is currently being used to treat diplopia. It has also been recognized as being a useful therapy for diplopia caused by muscle overactivity, such as convergence spasm.26 The effects of botulinum toxin are not permanent, but last for weeks or months. This
American Orthoptic Journal
allows the drug to be used as a temporizing agent for acute diplopia,27 since these conditions often resolve spontaneously over a similar time period. Bupivicaine injection into an ocular muscle induces hypertrophy and increased stiffness of muscle tissue, and this effect has been reported to help treat strabismus.28 CONCLUSIONS Orthoptists are uniquely qualified to assist in diagnosing, administering, and overseeing a patient’s rehabilitation for diplopia. They are able to provide nonsurgical therapy and to interact with providers who might be needed to provide medical and surgical intervention. Nonsurgical therapy for diplopia is often an adjunct to surgical therapy. The orthoptist must be able to help adjust therapy as the patient’s condition goes from acute to chronic. Finally, the patient’s acceptance of their condition and the limitations of treatment must be carefully explained to help the patient maintain realistic expectations. REFERENCES 1. Beauchamp GR, Felius J, Stager DR, Beauchamp CL: The utility of strabismus in adults. Trans Am Ophthalmol Soc 2005; 103:164-171; discussion 171-172. 2. Clark RA, Demer JL: Enhanced vertical rectus contractility by magnetic resonance imaging in superior oblique palsy. Arch Ophthalmol 2011; 129:904-908. 3. Lee RM, Dubois VD, Mavrikakis I, Okera S, Ainsworth G, Vickers S, Liu CS: Opaque intraocular lens implantation: A case series and lessons learnt. Clin Ophthalmol 2012; 6:545-549; e-pub April 5, 2012. 4. Laria C, Alió JL, Piñero DN: Intrastromal corneal tattooing as treatment in a case of intractable strabismic diplopia (double binocular vision). Binocul Vis Strabismus Q 2010; 25:238-242. 5. Velez FG, Isobe J, Zealear D, et al.: Toward an implantable functional electrical stimulation device to correct strabismus. J AAPOS 2009; 13:229-235; e-pub April 16, 2009. 6. Kirschen D, Flom MC: Monocular central-field
67
DIPLOPIA TREATMENT
7.
8. 9. 10.
11.
12.
13.
14.
15.
16.
17.
18.
68
occlusion for intractable diplopia. Am J Optom Physiol Opt 1977; 54:325-331. Routt LA: Monocular partial/ sector occlusion therapy: A procedure to inhibit diplopia in Brown syndrome. Optometry 2011; 8:207-211; e-pub January 7, 2011. Astin CL: The use of occluding tinted contact lenses. CLAO J 1998; 24:125-127. London R: Monovision correction for diplopia. J Am Optom Assoc 1987; 58:568-570. Migneco MK: Alleviating vertical diplopia through contact lenses without the use of prism. Eye Contact Lens 2008; 34:297-298. Udina E, Cobianchi S, Allodi I, Navarro X: Effects of activity-dependent strategies on regeneration and plasticity after peripheral nerve injuries. Ann Anat 2011; 193:347-353; e-pub March 17, 2011. Serna A, Rogers DL, McGregor ML, Golden RP, Bremer DL, Rogers GL: Treatment of symptomatic convergence insufficiency with a home-based computer orthoptic exercise program. J AAPOS 2011; 15:140-143; e-pub March 31, 2011. Deshpande SB, Ghosh RK: Study of primary convergence insufficiency. Indian J Ophthalmol 1991; 39:112-114. Safra D: The accommodation- convergence bar (A+C bar). Klin Monbl Augenheilkd 1990; 196:101-102. Veagan: Convergence and divergence show large and sustained improvement after short isometric exercise. Am J Optom Physiol Opt 1979; 56:23-33. Guliaev VI, Fedorov AA, Lobanova LS: [Electrodiagnostics and electrostimulation for the combined treatment of concomitant squint in children] (translated from Russian). Vopr Kurortol Fizioter Lech Fiz Kult 2010; 5:44-46. Flanders M, Sarkis N: Fresnel membrane prisms: Clinical experience. Can J Ophthalmol 1999; 34:335-340. Tamhankar MA, Ying GS, Volpe NJ: Success of
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
prisms in the management of diplopia due to fourth nerve palsy. J Neuroophthalmol 2011; 31:206-209. Reinecke RD, Simons K, Moss A, Morton G: An improved method of fitting resultant prism in treatment of two-axis strabismus. 21. Arch Ophthalmol 1977; 95:1255-1257. Politzer T, Cilo M, Weintraub A: A new prism use for treatment of cyclo-deviation in trochlear nerve injury. Neurorehabilitation 2010; 27:255-259. Christoff A, Guyton DL: How to measure slaboff and reverse slab prism in spectacle lenses. J AAPOS 2007; 11:414-415. Kupersmith MJ, Ying G: Ocular motor dysfunction and ptosis in ocular myasthenia gravis: Effects of treatment. BJO 2005; 10:1330-1334. Haines SR, Thurtell MJ: Treatment of ocular myasthenia gravis. Curr Treat Options Neurol 2012; 14:103-112. Kim TW, Kim JH, Hwang JM: Long-term outcome of patients with large overcorrection following surgery for exotropia. Ophthalmologica 2005; 219:237-242. Hiatt RL: Medical management of accommodative esotropia. J Pediatr Ophthalmol Strabismus 1983; 20:199-201. Kaczmarek BB, Dawson E, Lee JP: Convergence spasm treated with botulinum toxin. Strabismus 2009; 17:49-51. Talebnejad MR, Sharifi M, Nowroozzadeh MH: The role of botulinum toxin in management of acute traumatic third-nerve palsy. J AAPOS 2008; 12:510-513; e-pub June 16, 2008. Scott AB, Alexander DE, Miller JM: Bupivacaine injection of eye muscles to treat strabismus. BJO 2007; 91:146-148; e-pub November 29, 2006.
Key words: diplopia, eye exercises, neurologic strabismus, nonsurgical treatment, orthoptic therapy, prisms
Volume 63, 2013
ABSTRACT The ocular motor pathways are complex and disorders of these pathways can be devastating for patients, in some cases leading to loss of employment and independence. Surgical intervention for these cases is not always warranted, possible, or even safe for some patients, and nonsurgical and orthoptic treatments can provide significant relief. This paper will discuss various treatment options, including eye exercises, prisms, optical manipulation, occlusion, and lifestyle changes.
INTRODUCTION The ocular motor pathways are complex. Disorders of these pathways can be devastating for patients, in some cases leading to loss of employment and independence. Surgical intervention for these cases is not always warranted, possible, or even safe for some patients, and nonsurgical and orFrom the 1Wilmer Eye Institute, Baltimore, Maryland, and the 2Family Eye Group, Lancaster, Pennsylvania. Reprint requests should be addressed to: Noelle S. Matta C.O., C.R.C., C.O.T., Family Eye Group, 2110 Harrisburg Pike, Ste. 215, Lancaster, PA 17601; e-mail: NoelleMatta@ gmail.com Presented in part at the International Strabismological Association (ISA) symposium on Eye Movement Disorders at the XII International Orthoptic Congress, Toronto, Canada, June 26-29, 2012.
thoptic treatments can provide significant relief. According to a survey of 140 adult patients with strabismus, the diplopia can be so problematic that 60% of them would be willing to trade part of their life expectancy in return for being rid of the problem.1 Depending on the cause of diplopia, treatment options include nonsurgical as well as surgical approaches. In this review, we will discuss the nonsurgical treatments for neurologic diplopia, including eye exercises, prisms, optical manipulation, occlusion, and lifestyle changes. The goal of treatment is to allow the patient to recover a premorbid quality of life and functioning. A trip to the orthoptist may allow patients to regain their independence and to be able to return to work.
© 2013 Board of Regents of the University of Wisconsin System, American Orthoptic Journal, Volume 63, 2013, ISSN 0065-955X, E-ISSN 1553-4448
American Orthoptic Journal
63
DIPLOPIA TREATMENT
NEUROLOGIC AND MECHANICAL DIPLOPIA Diplopia can arise from mechanical or neurologic etiologies. Mechanical causes of diplopia stem from trauma to the extraocular musculature (EOM), their tendons or the bony orbit to which they are attached, as well as from infectious, inflammatory, or neoplastic diseases of those tissues, and also from dystrophic diseases of the muscles. Restrictive strabismus can occur when the muscles are inflamed or infiltrated, as in Graves’ ophthalmopathy, or when eye muscles are dystrophic, as in the mitochondrial myopathy of chronic progressive external ophthalmoplegia. These disorders can also lead to a paralytic strabismus. Neurologic causes of diplopia stem from similar disease states affecting the nerves innervating the EOM). These diseases might affect the nerve-muscle synapse (e.g., myasthenia gravis), the axons or cranial ganglia (e.g., vaso- occlusive disease, aneurysm), as well as the supranuclear control centers of eye movement (e.g., intracranial hypertension). It should be noted that the dichotomy between neurologic and mechanical diplopia is not absolute; neurologic diplopia can lead to atrophy of denervated muscles, and secondary hypertrophy of yoked or antagonist muscles, which adds a mechanical component to the strabismus.2 THE ORTHOPTIC EXAMINATION The orthoptist can measure many facets of a patient’s visual function, including: • Measurement of strabismus in various positions of gaze (by sensorimotor exam and/or Lancaster/Hess chart) • Best-corrected visual acuity (distance and near) • Visual function in preverbal and nonverbal patients
64
• Extraocular motility including versions and ductions • Stereopsis (distance and near) • Pursuit movements • Saccade movements • Accommodative amplitudes • Convergence/divergence amplitudes (horizontal and vertical) • Field of binocular single vision • Evaluation for the presence of phorias/tropias • Evaluation of nystagmus • Torsional abilities including evaluating for the presence of torsional strabismus • Evaluation of retinal correspondence • Evaluation of suppression and measurements of suppression scotoma • Evaluation of proptosis and hypo/ hyper globus • Measurements of eyelids and eyelid function • Evaluation of a patient’s old photos to look for onset/progression of disease • Evaluation of pupil function However, it is also important that the exam includes a careful assessment of the patient’s visual needs. It is helpful for a patient to create a prioritized list of things with which they are struggling. The patient has to understand that each issue may require a separate appointment and separate treatment because many conditions cannot simply be treated with one pair of glasses or a set of exercises. Visual needs can be divided into six categories. These include near, intermediate, and far distance work, and each one has requirements for either short or long duration. The Table provides some common tasks that fit into these categories, although it should be remembered that many tasks could be appropriate for more than one category. Once a patient shares their priorities, the orthoptist should help them set realistic expectations. Patients must be
Volume 63, 2013
SINGMAN
TABLE SAMPLING OF VISUAL TASKS AT DIFFERENT DISTANCES AND DURATIONS Visual Tasks
Short Duration
Long Duration
Near
• • • • • • • • • • • •
• • • • • • • • • • •
Intermediate
Far
Reading a medicine bottle Reading a telephone book Looking at a mobile phone Writing a check Card and board games Eating a meal Cooking Looking at prices at the grocery store Casual sightseeing Glancing at road signs Golf Glancing at a clock or a person walking into a room
Reading a book Reading a newspaper Writing a letter Sewing/knitting Using a computer Reading music Operating machinery Playing video games on a TV Driving a vehicle Watching a movie Watching a live sporting event
guided to understand that the efferent visual pathways are often far too complex to be improved with one treatment. Furthermore, although multiple aids may be provided, the patient may not recover all the functions they enjoyed in the premorbid state. Finally, a patient’s ability to regain fused vision in primary gaze may not translate into a full field of single binocular vision.
tattooing to block light from entering the pupil has been successfully attempted in Spain.4 Another avenue of research is the direct electrical stimulation of the extraocular muscles, with the eventual goal of creating an implantable prosthesis to reanimate a denervated eye muscle.5
MEDICAL AND SURGICAL THERAPIES FOR DIPLOPIA
Nonsurgical therapies work to help the patient either ignore or fuse diplopic images while carrying a lower risk of morbidity.
Medical therapies for diplopia can help patients achieve fusion by altering the strength (weakening or strengthening) of the EOMs through systemically provided or locally injected medications so that they can position the eyes to fixate upon a common point. Surgical therapies for diplopia involve manipulating the insertions or functional lengths of the EOMs to change the power they exert in their respective ranges of motion. A novel surgical approach of implanting an opaque intraocular lens in one eye to effectively render a patient monocular has been explored in England to treat patients with intractable diplopia, but this procedure is not performed in the United States.3 A new procedure involving intrastromal corneal
American Orthoptic Journal
NONSURGICAL THERAPIES AVAILABLE FOR DIPLOPIA
Monocularity Occluding either eye will effectively eliminate diplopia. For acutely ill patients, this is a safe and readily available technique. Elastic patches are often provided for this purpose, but these become soiled quickly and can lead to infection. In addition, occluding all vision to the patient’s eye reduces peripheral vision and peripheral fusion. Preferably, transparent tape covering the optical center and approximately half the surface area of one lens of a patient’s spectacles should be provided.6 If patients do not normally wear eyeglasses, nonprescription sunglasses
65
DIPLOPIA TREATMENT
or over-the-counter bifocals with a plano distance portion can be used. In patients who suffer diplopia in a particular field of gaze but can fuse in primary position, such as those with Brown syndrome, monocular occlusion of the appropriate sector of their eyeglasses can be helpful.7 If it becomes clear that a patient’s diplopia will be intractable, long-term options should be considered. For example, occlusive or tinted contact lenses can be made for those patients who do not wear spectacles.8 Diplopia can also be eliminated through monocular means without occlusion. For example, patients can be fitted with monovision eyeglasses9 or contact lenses.10 In addition, a prism can be used to increase the separation of diplopic images by purposefully over-correcting the angle of deviation, and this approach can make it easier for the patient to ignore the second image.
the “pencil push-ups” that are often prescribed for convergence insufficiency, although effective when performed properly, can now be replaced with computerized orthoptic programs available for home use. 12 Office- based exercise programs, such as those utilizing the synoptophore, may be preferred for patients who need a more structured environment for learning.13 Other low-tech options include the accommodation-convergence bar,14 pen or dot convergence therapy, prism vergence exercises to build fusional vergence amplitudes,15 stereograms, the Brock string, and the three-dot card. It should be noted that external, electrical stimulation of the extraocular muscles has been reported in Russian literature for the treatment of strabismus,16 but there is scant literature written in English concerning this topic.
Orthoptic Exercises
Prisms
Consistent with other muscle systems in the body, the EOM system responds to stimulation with growth and to disuse with atrophy. For example, in patients with chronic superior oblique palsy, the paretic muscle may become atrophic while the contralesional superior rectus can become hypertrophic.2 This hypertrophy might be secondary to the excess innervation to compensate for the relative hypotropia of the eye with the intact superior oblique. The mechanism by which stimulation leads to more robust muscle activity may be due in part to the release of trophic factors.11 Use-enhanced muscle function is the basis for offering orthoptic exercises to patients. Patients with diplopia, particularly those that can still fuse but experience intermittent heterotropias secondary to reduced vergences (horizontal and vertical), often respond very well to exercises. Patients need to be highly motivated for these exercises to be effective. Fortunately,
Prism therapy can reliably establish single binocular vision in at least one field of gaze.17, 18 Fresnel prisms can be applied to a patient’s eyeglasses, and methods have been described wherein a single, obliquely oriented prism can even compensate for both horizontal and vertical diplopia19 or even for a torsional component.20 Patients will sometimes recognize that field of single binocular vision is much smaller than before. Because the eyes converge with near work and diverge with distance vision, a patient can sometimes require different prism corrections in their glasses for different visual tasks, which may lead to the need for separate pairs of glasses. These may contain different prescriptions and prism amounts, or else ground-in prism with a Fresnel in the top of the lens or in the bifocal segment. Prism that is ground into a lens has the advantages over Fresnel prism applied to a lens in that it will give a clearer image, will be easier to clean, and will not fall off.
66
Volume 63, 2013
SINGMAN
However, they are more expensive and increase lens weight and thickness, depending on the power. In addition, it is much more difficult to grind different prism power into the distance and reading portions of the same lens. Fresnel prisms allow the flexibility of easily altering prism power as a patient’s condition improves or worsens.21 Medical Nonsurgical Therapies Some medical nonsurgical therapies are beyond the scope of orthoptists but deserve mention, since it is likely that orthoptists will encounter patients who might benefit from these treatments. Anticholinesterases (e.g., pyridostigmine) and/or steroids (e.g., prednisone) are systemically administered for the treatment of myasthenia gravis. Recent research suggests that prednisone may be more effective than pyridostigmine for treating the diplopia associated with myasthenia gravis.22 Other medical nonsurgical therapies available for ocular myasthenia gravis include plasmapheresis, intravenous immunoglobulin and immunosuppressive agents.23 Anticholinesterases administered topically (phospholine iodide) have been used in the past to treat esotropia secondary to surgical over-correction of exotropia.24 This eye drop was sometimes used as an adjunctive therapy for accommodative esotropia, but it is rarely used for this condition anymore.25 Minimally Invasive Therapies Botulinum toxin injection for chemically denervating (i.e., weakening) muscles with relatively insufficient opposition is currently being used to treat diplopia. It has also been recognized as being a useful therapy for diplopia caused by muscle overactivity, such as convergence spasm.26 The effects of botulinum toxin are not permanent, but last for weeks or months. This
American Orthoptic Journal
allows the drug to be used as a temporizing agent for acute diplopia,27 since these conditions often resolve spontaneously over a similar time period. Bupivicaine injection into an ocular muscle induces hypertrophy and increased stiffness of muscle tissue, and this effect has been reported to help treat strabismus.28 CONCLUSIONS Orthoptists are uniquely qualified to assist in diagnosing, administering, and overseeing a patient’s rehabilitation for diplopia. They are able to provide nonsurgical therapy and to interact with providers who might be needed to provide medical and surgical intervention. Nonsurgical therapy for diplopia is often an adjunct to surgical therapy. The orthoptist must be able to help adjust therapy as the patient’s condition goes from acute to chronic. Finally, the patient’s acceptance of their condition and the limitations of treatment must be carefully explained to help the patient maintain realistic expectations. REFERENCES 1. Beauchamp GR, Felius J, Stager DR, Beauchamp CL: The utility of strabismus in adults. Trans Am Ophthalmol Soc 2005; 103:164-171; discussion 171-172. 2. Clark RA, Demer JL: Enhanced vertical rectus contractility by magnetic resonance imaging in superior oblique palsy. Arch Ophthalmol 2011; 129:904-908. 3. Lee RM, Dubois VD, Mavrikakis I, Okera S, Ainsworth G, Vickers S, Liu CS: Opaque intraocular lens implantation: A case series and lessons learnt. Clin Ophthalmol 2012; 6:545-549; e-pub April 5, 2012. 4. Laria C, Alió JL, Piñero DN: Intrastromal corneal tattooing as treatment in a case of intractable strabismic diplopia (double binocular vision). Binocul Vis Strabismus Q 2010; 25:238-242. 5. Velez FG, Isobe J, Zealear D, et al.: Toward an implantable functional electrical stimulation device to correct strabismus. J AAPOS 2009; 13:229-235; e-pub April 16, 2009. 6. Kirschen D, Flom MC: Monocular central-field
67
DIPLOPIA TREATMENT
7.
8. 9. 10.
11.
12.
13.
14.
15.
16.
17.
18.
68
occlusion for intractable diplopia. Am J Optom Physiol Opt 1977; 54:325-331. Routt LA: Monocular partial/ sector occlusion therapy: A procedure to inhibit diplopia in Brown syndrome. Optometry 2011; 8:207-211; e-pub January 7, 2011. Astin CL: The use of occluding tinted contact lenses. CLAO J 1998; 24:125-127. London R: Monovision correction for diplopia. J Am Optom Assoc 1987; 58:568-570. Migneco MK: Alleviating vertical diplopia through contact lenses without the use of prism. Eye Contact Lens 2008; 34:297-298. Udina E, Cobianchi S, Allodi I, Navarro X: Effects of activity-dependent strategies on regeneration and plasticity after peripheral nerve injuries. Ann Anat 2011; 193:347-353; e-pub March 17, 2011. Serna A, Rogers DL, McGregor ML, Golden RP, Bremer DL, Rogers GL: Treatment of symptomatic convergence insufficiency with a home-based computer orthoptic exercise program. J AAPOS 2011; 15:140-143; e-pub March 31, 2011. Deshpande SB, Ghosh RK: Study of primary convergence insufficiency. Indian J Ophthalmol 1991; 39:112-114. Safra D: The accommodation- convergence bar (A+C bar). Klin Monbl Augenheilkd 1990; 196:101-102. Veagan: Convergence and divergence show large and sustained improvement after short isometric exercise. Am J Optom Physiol Opt 1979; 56:23-33. Guliaev VI, Fedorov AA, Lobanova LS: [Electrodiagnostics and electrostimulation for the combined treatment of concomitant squint in children] (translated from Russian). Vopr Kurortol Fizioter Lech Fiz Kult 2010; 5:44-46. Flanders M, Sarkis N: Fresnel membrane prisms: Clinical experience. Can J Ophthalmol 1999; 34:335-340. Tamhankar MA, Ying GS, Volpe NJ: Success of
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
prisms in the management of diplopia due to fourth nerve palsy. J Neuroophthalmol 2011; 31:206-209. Reinecke RD, Simons K, Moss A, Morton G: An improved method of fitting resultant prism in treatment of two-axis strabismus. 21. Arch Ophthalmol 1977; 95:1255-1257. Politzer T, Cilo M, Weintraub A: A new prism use for treatment of cyclo-deviation in trochlear nerve injury. Neurorehabilitation 2010; 27:255-259. Christoff A, Guyton DL: How to measure slaboff and reverse slab prism in spectacle lenses. J AAPOS 2007; 11:414-415. Kupersmith MJ, Ying G: Ocular motor dysfunction and ptosis in ocular myasthenia gravis: Effects of treatment. BJO 2005; 10:1330-1334. Haines SR, Thurtell MJ: Treatment of ocular myasthenia gravis. Curr Treat Options Neurol 2012; 14:103-112. Kim TW, Kim JH, Hwang JM: Long-term outcome of patients with large overcorrection following surgery for exotropia. Ophthalmologica 2005; 219:237-242. Hiatt RL: Medical management of accommodative esotropia. J Pediatr Ophthalmol Strabismus 1983; 20:199-201. Kaczmarek BB, Dawson E, Lee JP: Convergence spasm treated with botulinum toxin. Strabismus 2009; 17:49-51. Talebnejad MR, Sharifi M, Nowroozzadeh MH: The role of botulinum toxin in management of acute traumatic third-nerve palsy. J AAPOS 2008; 12:510-513; e-pub June 16, 2008. Scott AB, Alexander DE, Miller JM: Bupivacaine injection of eye muscles to treat strabismus. BJO 2007; 91:146-148; e-pub November 29, 2006.
Key words: diplopia, eye exercises, neurologic strabismus, nonsurgical treatment, orthoptic therapy, prisms
Volume 63, 2013
