Persistent Diplopia in treatment that either establishes fusion or Visually Mature Patients. reactivates a preexisting sensory adaptation. This case series reviews these other causes of Is it Intractable or diplopia. something else? A Review and Case Series INTRODUCTION Robert P. Rutstein, OD, MS, FAAO Diplopia is the condition in which a single Professor Emeritus School of image is perceived simultaneously as being two Optometry, University of Alabama rather than one.1 When on examination there is at Birmingham Birmingham, Alabama inability to fuse the two images and also suppress the second image, the diplopia is intractable.2,3 Intractable diplopia is constant and occurs in all ARTICLE positions of gaze despite achieving satisfactory ocular alignment with either prisms, lenses, ABSTRACT vision therapy, extraocular muscle surgery, or Diplopia is described as being intractable when botulinum toxin injection. Some patients may there is inability to both fuse the two images actively avoid fusion by performing involuntary and suppress the second image. Intractable ocular movements of their nonfixating eye, diplopia persists despite achieving ocular reporting one image jumping over the other alignment using either prisms, lenses,vision when the strabismus is neutralized either with therapy,extraocular muscle surgery, or botul- prisms or with haploscopic devices such as the inum toxin injection. Treatment usually synoptophore.4-6 resorts to occluding or fogging the patient’s Since fusion cannot be established, nondominant eye. Often times, however, treatment for intractable diplopia is usually adults having other causative mechanisms palliative. Occlusion or fogging of the for supposedly persistent diplopia are able nondominant eye with patches,3 frosted to achieve comfortable single vision with spectacle lenses,7 partially occlusive filters,8,9 monovision glasses or monovision contact 10,11 3,7,12 Correspondence regarding this article should be lenses, occlusive contact lenses, corneal emailed to Robert P. Rutstein, OD, MS, FAAO at tatooing,13,14 opaque intraocular lenses,15,16 and [email protected]. All state ments are the author’s 13 personal opinions and may not reflect the opinions of botulinum toxin induced ptosis have been the College of Optometrists in Vision Development, used to ameliorate intractable diplopia. Vision Development & Rehabilitation or any institu tion Although it has historically been reported or organization to which the author may be affiliated. Permission to use reprints of this article must be obtained to be a consequence of either amblyopia or from the editor. Copyright 2017 College of Optometrists strabismus treatment, the consensus is that in Vision Development. VDR is indexed in the Directory 17-21 of Open Access Journals. Online access is available at intractable diplopia occurs infrequently. covd.org. https://doi.org/10.31707/VDR2017.3.2.p90 Cumulative findings from three studies involving adults manifesting constant strabismus without Rutstein R. Persistent diplopia in visually mature patients. Is it intractable or something else? A Review diplopia prior to extraocular muscle surgery and Case Series Vision Dev & Rehab 2017;3(2):90-108. reported intractable diplopia developing in only 12 of 899 patients (1.3%) postoperatively.22-24 Furthermore, strabismus that began in early Keywords: adult onset, childhood onset, childhood and either was untreated or diplopia, intractable, sensory testing, treated and recurred is usually accompanied strabismus, visually mature by sensory adaptations such as suppression 90 Vision Development & Rehabilitation Volume 3, Issue 2 • July 2017 and/or anomalous retinal correspondence subjective angle of 22 PD - 24 PD base-out which prevent diplopia.25,26 However, in some confirming anomalous retinal correspondence. instances these sensory adaptations may not The diagnosis was consecutive exotropia be permanent and can be changed or lost over with intractable diplopia. Bangerter filters and/ the years as illustrated in Case 1. or +2 D (diopter) and +3 D Fresnel lenses placed over the left spectacle lens to eradicate Case 1 the diplopia were uncomfortable for the A 17 year – old high school student was patient. This was attributed to the blur possibly referred for constant and long- standing increasing the dissociated vertical deviation. horizontal diplopia which he described as A 0.2 density Bangerter filter providing sector minimally bothersome. He desired to obtain a occlusion and restricted to the central portion driver’s license. of the left spectacle lens used exclusively for Ocular history was significant for bilateral driving was more acceptable.27 optic neuritis and uveitis at 4 months of Strabismus beginning in adulthood causes age. The patient’s systemic history was diplopia that usually resolves and fusion unremarkable. Extraocular muscle surgery in reestablished when the eyes are accurately the left eye for probable infantile esotropia aligned prismatically or surgically. However, occurred at 3 years of age. Bilateral cataract intractable diplopia has been reported following surgery was performed at 8 years of age and prolonged visual deprivation due to cataract or YAG capsulotomy in the right eye at 14 years from uncorrected unilateral aphakia in adults of age. Prism glasses were prescribed when with sensory strabismus who eventually received he was 12 years old but was not helpful. He secondary intraocular lens implantation.28-32 denied having had any patching or orthoptics/ Intractable diplopia has also been reported vision therapy. following severe head injury, ocular trauma, On examination refractive correction and central nervous system disorders, post viral corrected visual acuities were right eye -1.25 syndromes, intracranial surgery, and cerebral – 2.50 x 14 (20/25) and left eye -1.50 -1.00 x vascular accident or stroke3-5 as illustrated in 155 (20/25). The diplopia, described as being Case 2. horizontal, was absent when either eye was covered. A constant left exotropia of 30 prism Case 2 diopters (PD) was revealed with the cover A 56 year-old man was referred with a test at distance and near. The exotropia was complaint of constant diplopia which began accompanied by bilateral dissociated vertical following a stroke three years ago. He deviation. Latent nystagmus was present in described the diplopia as being both vertical the left eye. Versions showed bilateral superior and horizontal and more bothersome when oblique overaction with larger exotropia in reading. The diplopia was absent with either downgaze. eye covered. He denied having strabismus and The patient responded to sensory testing any other eye disorders during childhood. The paradoxically as if he was esotropic. With the referring practitioner prescribed prism glasses Worth 4-dot and red lens tests at both distance that did not alleviate the diplopia. There had and near, the diplopia was uncrossed rather not been any strabismus surgery performed. than crossed, suggesting anomalous retinal On examination, refractive correction and correspondence. The diplopia could neither visual acuities were right eye Pl – 0.50 x 75 be fused nor suppressed with any amount of (20/20) and left eye Pl – 0.50 x 110 (20/20). He prism. Synoptophore evaluation measured manifested with the cover test a left hypertropia an objective angle of 30 PD base – in and a of 10 PD in primary gaze at distance and near. 91 Vision Development & Rehabilitation Volume 3, Issue 2 • July 2017 An 8 degree right excyclotorsion was measured with the synoptophore. Due to the lack with the double Maddox rod. Versions showed of demonstrable motor fusion, this most limited elevation in the right eye and limited likely indicated superimposition of the depression in the left eye. With the doll’s head synoptophore targets rather than actual (oculocephalic reflex) maneuver, versions in sensory fusion of the targets. both eyes improved suggesting a supranuclear cause for the impaired ocular motility. Since intractable diplopia can have a Sensory testing with the Worth 4-dot test substantial impact on the patient’s quality of life showed vertical diplopia at both distance and and occurs infrequently, it should be a diagnosis near. Stereopsis with the contour stereotargets of exclusion and made only after other causes (circles) of the Randot stereotest (Stereo of diplopia have been ruled out.3,22,33,34 Many Optical Co, Inc, Chicago, ILL) was nil. With patients I have examined over the years had the synoptophore which compensated for other types of diplopia that could be treated the torsional as well as the vertical deviation, without constantly occluding or fogging one normal retinal correspondence and “fleeting eye. They were able to achieve comfortable sensory fusion” were demonstrated. Motor single vision by either changing their optical fusion was extremely poor. Moving the tubes prescription, altering their fixation pattern or of the synoptophore less than 1 PD in any head posture, using prisms, or undergoing direction caused diplopia. vision therapy or extraocular muscle surgery. It was noted that the present glasses had The purpose of this report is to review other ground-in prism with 3 PD base-down in the types of diplopia that should be considered right lens and 8 PD base-up in the left lens, in adults and visually mature patients with which corrected for left hypotropia, not left persistent diplopia. Representative case reports hypertropia. Using glasses without ground- are included. in prism, treatment included 8 PD base-up