Non-Surgical Management of Strabismus

An overview of non-surgical treatment of strabismus.

Alex Christoff Orthoptist Assistant Professor of Ophthalmology The Wilmer Eye Institute at Johns Hopkins  Strabismus surgery is an effective treatment in adults with symptomatic strabismus.  There are times when surgery is not indicated;  When there is concern for anesthetic risk  When the deviation is dynamic or unstable - as in patients recovering from cranial nerve paresis  When the deviation is small in a patient already wearing habitual spectacles for pre-existing refractive error  When the patient elects not to do so.  In these situations, the clinician will need to devise alternative options for addressing the patient’s chief complaint of diplopia.  The typical patient is an adult or young adult with symptomatic strabismus.  Etiologies are varied, and can include:  Mechanical strabismus from prior scleral buckling or complex eye muscle procedures1-2  Restrictive strabismus from orbital diseases such as Grave’s orbitopathy, cranial nerve paresis from intracranial ischemic or neoplastic processes3-8  Local anesthetic injury or toxicity after ocular surgery9  Strabismus following endoscopic sinus surgery  Nonsurgical treatment options include refraction, prisms or occlusion.  Refraction is a logical first step for addressing diplopia in adult patients with reduced acuity in one or both eyes at presentation  Especially when there is a previous or early-childhood history of strabismus  In patients with small-angle manifest strabismus or symptomatic phorias  In some adult cases, especially there is a previous history of early-childhood esotropia treated with hypermetropic spectacles, correction of residual hypermetropia (plus power) will relax accommodative convergence enough to also resolve symptoms associated with small angle esophorias or esotropias  Similarly, correction of residual myopia (minus power) might stimulate accommodative convergence enough to also resolve symptoms associated with small angle exophorias or exotropias  Treatment of diplopia with prism involves quantifying the deviation by prism and cover testing at distance and near  Temporary, Press-On™ prism is then applied to the spectacle lens base In, base out, base up or base down  Prism options are limited by the commercially available powers of Fresnel Press-On™ prisms (in increments of 1 from 1 to 10, a power of 12, and in increments of five from 15 to 40).  Cycltorsional misalignment associated with restrictive strabismus, and assessed by double Maddox rod testing, may preclude the use of prism in these patients.  Clinical techniques to measure and treat mixed horizontal and vertical strabismus with a unilateral, Press-On® prism have been described by others (ref)  Again, methods involve quantifying the vertical and horizontal components of the deviation with prism and cover testing, then applying the Pythagorean theorem to come up with a diagonal/oblique equivalent, and then consulting reference tables that specify the resultant power and angle at which to prescribe the oblique prism  Temporary, Press-On™ prism is then applied to the spectacle lens using a compass rose which aids in accurate tracing, cutting, and application of the prism and positioning of its base.  The specific etiology of the oblique strabismus is generally irrelevant when recommending prism designed to ameliorate symptoms only in the primary positions of distance and near fixation, or in the reading position,  So diagnostic full-field measurements of the strabismus are unnecessary.  Occlusion of the involved eye may be partial or complete  Black "pirate" patch / Adhesive patch  Occlusion of the involved eye may be partial or complete  Bangerter filter foil can be titrated for greater or lesser levels of occlusion10  Occlusion of the involved eye may be partial or complete  Scotch® Satin tape  Placed centrally across the visual axis  On the inner surface of the patient’s spectacle lens.  $3.34 3-pack retail  Not universally tolerated 1. Hwang JM, Wright KW:Combined study on the causes of strabismus after the retinal surgery. Korean J Ophthalmol 1994; 8:83-91. 2. Capo H, Guyton DL: Ipsilateral hypertropia after cataract surgery. Ophthalmology 1996; 103: 721-730. 3. Johnson DA: Persistent vertical binocular diplopia after cataract surgery. Am J Ophthalmol 2001; 132:831-835. 4. Dobler-Dixon AA,Cantor LB, Sondhi N, Ku WS, Hoop J: Prospective evaluation of extraocular motility following doubleplate molteno implantation. Arch Ophthalmol1999; 117:1155-1160. 5. 7. Christmann LM, Wilson ME: Motility disturbance after Molteno implants. J Pediatr Ophthalmol Strabismus 1992; 29:4448. 6. 8. Guo S, Wagner S, Gewirtz M, Maxwell D, Pokorny K, Tutela A, Caputo A, Zarbin M: Diplopia and strabismus following ocular surgery. Surv Ophthalmol 201O; 55:335-358. 7. 9. Kang SJ, Jang JH: Motility restriction after resection of an extraocular muscle. Korean J Ophthalmol2001;15:133-136. 8. 10. Ela-Dalman N, Velez FG, Rosenbaum AL: Incomitant esotropia following pterygium excision surgery. Arch Ophthalmol2007; 125:369-373. 9. Salama H, Farr AK, Guyton DL: Anesthetic myotoxicity as a cause of restrictive strabismus after scleral buckling surgery. Retina 2000; 20:478-482. 10. Fraine, L. Nonsurgical Management of Diplopia. Am Orthop J. 2012. Vol 62, pp 13-18.