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MY APPROACH to Transferring From Pharmaceutical to Rehabilitative Management of Anisometropic Amblyopia
In recent years, atropine penalization has become a popular, acceptable treatment option for patients with refractive amblyopia as an alternative to patching. The purpose of atropine penalization is to immobilize the focusing system in the patient’s preferred eye, leaving the non-preferred eye the opportunity to learn to aim and focus, effectively picking up the slack while the “good eye” is out of commission. The following case illustrates how a patient being treated with the pharmaceutical approach was transitioned into active, short-term rehabilitative treatment, along with short-term atropinization with sustainable results.
Presenting profile
Patient JB presented at age 5.4 years for a third opinion to her current care for amblyopia and intermittent esotropia (ET) of the right eye (OD). She had initially undergone 9 months of patching and then daily atropine (1%) penalization of her left eye (OS) after patching regimens had been unsuccessful. Patient compliance with atropine was met with resistance. Attempts to discontinue atropine did not show sustained gains in acuity, and atropine penalization was reinstituted and monitored closely over the course of a year. At the time of presentation, atropine was being used every other day. JB’s mother sought alternative options with vision therapy and rehabilitation. She cited concerns that her daughter tends to bump into things, has trouble walking downstairs, and is very cautious. She reported that her daughter has a bad sense of orientation and has gotten lost in large areas. She also noted that there seem to be some challenges with drawing, but that her daughter is extremely bright when it comes to verbal skills and auditory learning.
Initial exam
Prior to conducting JB’s first exam, I asked her mother to switch atropine treatment to a nighttime dose OS, every other night. Her last dosage was taken approximately 40 hours before evaluation.
Prior to entering the office, JB was observed walking into the exam room. She ambled to her chair as directed with her posture bent slightly forward. She was quiet and reserved, but a compliant and willing participant.
Entering visual acuities (VAs) with her current prescription were OD +2.75 sph, 20/40; OS +0.25 sph 20/30−; both eyes (OU) 20/30 OU. Near acuities (at 16”) were slightly better, but JB leaned in and tipped her chin down for visual acuities of 20/32 OD, 20/25 OS, 20/32 OU. Retinoscopy showed anisometropic hyperopia, measuring OD +4.75 sph; OS +1.50 sph. Visual acuities, when measured in the phoropter, were the same OS but slightly reduced OD to 20/50 −2 OD, which is not uncommon in patients with fixation difficulties.
Using a “Van Orden Star” in a telebinocular as a target to assess visually guided motor behavior, JB experienced profuse tearing and demonstrated poor aim with each eye but did not complain or request to discontinue the task. Cover testing revealed 8^ esophoria (EP) at distance and near, although she may well have been in a small-angle ET posture and not re-fixating, given the fact that random dot stereo (RDS) was absent and stereoacuity was depressed to 100” on Wirt circles. Ocular motility testing was extremely poor, with the inability to maintain fixation with either eye or binocularly in any direction of gaze. She exhibited substantial movement of her head and trunk on smooth pursuit testing, and showed no attempts to fixate and follow beyond central 10°. Worth 4-dot revealed flat fusion with OS sensory dominance at both distance and near. Near-point retinoscopy (assessment of focus during an active reading task) showed symmetric use of the eyes as a team with +4.00 sph OD/ +1.25 sph OS.
Walking was reassessed through the above prescription, and ambulation was unimpeded with the additional plus power. In order to raise awareness of her surroundings, yoked prism was trialed, 1 prism diopter (PD) base down (BD) OU, which stabilized JB’s gait and righted her posture. This was prescribed for full-time wear. She was also instructed to continue 1% atropine OS every other night in order to provide monocular fixation of the right eye in a binocular field, without over-penalizing the left eye. (The left eye was also demonstrating reduced visual acuity and was at risk for bilateral amblyopia with long-term penalization.)
Rehabilitative support
Clinically, JB’s severe deficits in fixation and oculomotor control were identified as primary modifiable factors in her amblyopia and binocularity. An initial 12-week course of therapy was implemented, which included visually guided motor activities integrated with a metronome and saccadic eye movements presented with either central–peripheral organization or left-to-right and top-to-bottom organization as encountered in reading. At near-point, fine motor control was engaged with touching or manipulating small objects with pincer grasp for visually guided motor control and feedback for accuracy. At longer distances, feedback was supported with aiming a flashlight and observing accuracy of motor control within a visual target. Visual information processing skills over a broad retinal area were trained, including visual–spatial memory exercises, encouraging viewing over an area with tachistoscopic exposure; and visual–sequential memory exercises, encouraging ability to track a moving target over a stable area and to reproduce the pattern. Smooth pursuit exercises were conducted with peg insertion into a rotating pegboard and practice following a swinging ball while adding cognitive tasks to improve automaticity of eye movements.
A re-evaluation after 12 weeks showed improvements in the visual acuity of the right eye (20/25), in stereoacuity (40” Wirt), and in fixation control with reduced head and body movement during ocular motility assessments. Atropine was discontinued, and her prescription was modified to flat-top bifocals with asymmetric adds. Anisometropia was found to decrease, with an increase in hyperopia of the left eye: OD +4.25 sph/ +1.25 ADD; OS +2.25 sph/ +0.75 ADD; vertical yoked prism was removed, as JB now demonstrated far greater spatial awareness. Her mother noted that JB was “smiling more.”
JB’s ability to sustain her therapy gains without atropine and with the support of the bifocal prescription was assessed after another 3 months. At that time, JB demonstrated improved quality of binocular performance at near, stereoacuity reached 20” Wirt circles and achieved RDS (250”); near acuities reached 20/20 right eye, 20/16 left eye, and 20/16 binocularly. Distance acuities continued to show slight reduction in the right eye to 20/30, and she continued to show an intermittent small-angle right ET (distance only). Ocular motility continued to show improvements in accuracy and body stability.
Vision therapy was continued for another 12 weeks to refine binocular and accommodative skills with her new-found improvements in fixation and tracking. Following this course, her ocular motilities were accurate and without head movement for saccades, pursuits, and vergence fixations. Her frequent tendency to tear with focusing and reading effort had resolved. Intermittent right ET continued to appear at distance only, but another refractive change post therapy has since helped her to maintain alignment at distance.
At age 6.4 years, JB experienced numerous quality-of-life improvements, including less shyness, fewer accidents, and far greater ease with reading, comprehension, and handwriting. Her mother reported JB was doing well in school, loves math, is well-organized, and she engages in soccer, piano, and singing. Acuity improvements at distance and near have sustained from age 6.4 through 6.9.
Although amblyopia is frequently characterized in terms of visual acuity, recent studies demonstrate a variety of measurable deficits, including binocular processing,1 contrast sensitivity,2,3 and motion sensitivity.4 These challenges may manifest with symptoms such as those described with JB, including poor orientation skills, mis-assessment of space, bumping into things, and poor performance in sports. These in turn can impact confidence in social and play environments, including shy behavior, as well as ease of performance in academic arenas.
The option of rehabilitative support enabled JB to take an active role in the use of her vision with long-term positive, sustainable impacts on quality of life.5 This can be offered in addition to pharmaceutical management, providing the parent with the security of compliance with the directions of the primary eye care provider. Quantitative and qualitative improvements provide the parent with comfort that the child may safely discontinue atropine therapy.
Additional Info
- Levi DM, Knill DC, Bavelier D. Stereopsis and amblyopia: a mini-review. Vision Res. 2015;114:17-30.
- Zhou Y, Huang C, Xu P, et al. Perceptual learning improves contrast sensitivity and visual acuity in adults with anisometropic amblyopia. Vision Res. 2006;46(5):739-750.
- Polat U, Ma-Naim T, Spierer A. Treatment of children with amblyopia by perceptual learning. Vision Res. 2009;49(21):2599-2603.
- Ho CS, Giaschi DE. Stereopsis-dependent deficits in maximum motion displacement in strabismic and anisometropic amblyopia. Vision Res. 2007;47(21):2778-2785.
- Levi DM, Li RW. Perceptual learning as a potential treatment for amblyopia: a mini-review. Vision Res. 2009;49(21):2535-2549.
Disclosure statements are available on the authors' profiles: