Unit IV 4.3 & 4.4 Management Strategy and Treatment Options in Pediatric Patients
- 1. Unit IV: Management Strategy and Treatment Options Dr. Rheza Marisse B. Tabasuares Instructor
- 2. Management Strategy and Treatment Options 4.1 The General Treatment Strategy 4.2 Lens Therapy 4.3 Prism Therapy 4.4 Occlusion Therapy 4.5 Active Vision Therapy 4.6 Pharmacological Therapy 4.7 Surgical Therapy
- 3. 4.3 PRISM THERAPY ➢ Patients present with varying degrees of strabismus. ➢ Diagnostically, strabismus may be termed as intermittent if the eyes are aligned part of the time or over a part of space. ➢ Fusion may be possible in a particular direction of gaze or over a limited range of distances. ➢ Strabismus may emerge as a result of a decompensated paretic muscle or for a variety of medical reasons. ➢ As long as the brain had a prior history of fusing two images into a single solid perspective, prisms may be employed as a means of helping the patient with intermittent strabismus to restabilize fusion.
- 4. ● Compensating prism may be considered in cases of strabismus when the patient is experiencing diplopia. ● Yoked prism can be useful for individuals with hemi-field loss. In addition, the use of yoked prism has been effective in enhancing self- organization and orientation of individuals in response to environmental–spatial demands, as well as body posture and gaze control.
- 5. ● More specifically, they have been found to improve both nonvisual and visual–motor task performance, such as ball catching, in individuals with autism. ● Yoked prism use has also been shown to reduce some characteristic symptoms in these individuals.The effect of wearing yoked prism is to deflect peripheral light rays, shifting space in a way that dramatically alters the patient’s view of the external world, which forces them to reorganize visual processes in order to achieve homeostasis. ● While initially remarkable, the effect of yoked prism may fade with time if the individual does not have the opportunity to integrate and to organize the perceptual changes that occur when wearing the prism.
- 6. A. Temporary application of prism: ➢ Temporary prism is readily provided with Fresnel press-on prisms. They adhere to the lens via static and can be cut at the proper orientation to fit the back surface of the lens, trimmed to just inside the frame. ➢ In the event of a transient strabismus, apply the temporary prism unilaterally to the deviating eye in order to avoid reducing image quality OU. Depending on eye preference and the prism strength required, Fresnel prism may not be tolerated as a unilateral temporary solution. In such cases, ground-in prism may be needed, or both Fresnel and ground-in prism can be applied in combination. ➢ There are limits to the amount of base-in prism that can be ground into an ophthalmic lens without interfering with the nose. In such cases, again, a combination of ground-in prism and Fresnel prism may be the best solution. The following strategies may be applied to enhance binocular performance in patients with strabismus:
- 7. B. Prism for vertical deviation: 1. It is helpful to begin with an assessment of the diagnostic action fields (DAF) in order to identify whether there is a particular area in which the deviation is greatest/smallest. Note that findings may differ depending on which eye is fixating. 2. Observe the presence of a head tilt or turn. Prism may be used to shift the images of both eyes toward the preferred field. This alleviates some of the negative side effects of maintaining an AHP over time. 3. Use trial prism to determine the least amount of prism power that helps the patient to recover binocularity in free space. Repeat for intermediate and near distances and different directions of gaze. 4. In the event of a depression deficit, use free-space testing at near in downgaze to apply sufficient base-down prism to the eye with the depression deficit. This may be applied unilaterally or asymmetrically. 5. Be sure to educate the patient if a different amount of prism is needed for distance fusion compared to near-point fusion. Sectoral application of Fresnel prism can be applied over a near-point add if necessary.
- 8. C. Prism for lateral deviation: 1. Horizontal prism may be added to a prescription if it facilitates fusion and/or vergence ranges. 2. Some medical issues respond well to the temporary application of lateral prism, including denervation of the lateral rectus (e.g., with diabetes) and transient impacts of proptosis and orbital changes (e.g., Graves disease). In such cases, temporary Fresnel prism may be sufficient. 3. Temporary prism may also be applied and decreased in power over time, functioning like training wheels, providing less and less external support over time while neuromuscular redistribution takes place.
- 9. D. Noncompensatory applications of prism: 1. Patients with dissociated vertical deviation (DVD) show a tendency for both eyes to drift upward. These patients often find relief with the application of yoked base-down prism. Generally, they do not tolerate base- up prism, so it is better not to try to split vertical prism in these patients. 2. The spatial impact of low-power prisms (also referred to as mini-prism) may have multiple positive effects. Prisms transform the path of light, not only via lateral displacement, but also with a net rotational change of the incoming light. At low prism powers (e.g., ½∆, 1∆, 1.5∆), the lateral displacement is small enough to go unnoticed for most patients who can make equivalent vergence changes with ease. In particular, low base-in prism creates a subtle horizontal image expansion.
- 10. 3. When provided OU, low base-in prism has been demonstrated to: - improve tracking abilities when reading - reducing the perceived letter crowding common in strabismic amblyopia and other functional vision disorders. 4. Aniseikonic lens designs, such as the Shaw lens, may also be used to reduce lens-induced image disparities while providing refractive compensation.
- 11. Shaw Lens is different…. https://www.youtube.com/watch?v=_idIDPBVegM&t=59s
- 12. A six-year-old girl had an eye exam several weeks prior, but her father was concerned that she was still moving her body instead of her eyes while writing. The patient’s medical history included ADHD and autism. She uses both Focalin (dexmethylphenidate, Novartis) and guanfacine. She was born on time and has been meeting all developmental milestones but is mildly delayed. She is not currently reading and receives speech and occupational therapy several times per week. Her father described her as “very clumsy” and said she bumps into things a lot at home. Case Study Clinical Findings: NVA OD 20/15 OS 20/15 OU 20/15 Stereo: 20 secs of arc Phoria: Orthophoria at distance and near Retinoscopy +0.50 -0.50x090 OU. MEM response through plano was +0.50 with fluctuations. Through +0.50, the response was plano with fewer fluctuations. Gross eye movement demonstrated significant issues on both pursuits and saccades, showing significant body overflow and head movement. When we were able to get her to sit down, the patient was fidgety in the chair, and she was jumpy otherwise.
- 13. Management We decided to trial 2.00D of base-up yoked prism. Interacting with the hanging Marsden ball, the patient’s attention was more focused with the yoked prism and she was better able to catch the ball. Her father commented that he had never seen his daughter so focused and with such good hand-eye coordination. We prescribed +0.25D of sphere with the 2.00D of base-up yoked prism OU and initiated a course of vision therapy focusing on eye and body movements. The patient is currently on her 10th session and progressing wonderfully. https://www.reviewofoptometry.com/article/make-way-for-yoked-prism
- 14. ● Passive treatment ● Occlusion of the sound eye is the most effective treatment for amblyopia treatment by forcing the patient to use the amblyopic eye. ● Mainstay of treatment since 18th century to till now. ● Highly effective until 8yo. ● Causes progressive changes in visual functioning. ● Success rate 30-92% ○ When fixation is central: simple & effective ○ When fixation is eccentric: <7 yo central fixation recover ○ The older the child, the harder to regain central fixation 4.4 Occlusion Therapy
- 15. Designed to improve visual performance by the patient’s conscious involvement in a sequence of a specific, controlled visual task that provide feedback 1. Pleoptics 2. Near Activities 3. Active stimulation therapy using CAM vision stimulator 4. Syntonic phototherapy 5. Role of perceptual learning 6. Binocular stimulation 7. Software-based active treatments These therapies are briefly described with occlusion therapy in detail. The patient experiences a change in visual stimulation without any conscious effort. 1. Proper refractive correction 2. Occlusion 3. Penalization 4. Pharmacological manipulation Passive Therapy Active Therapy
- 16. Prevent fixating eye taking part in act of vision and removes inhibitory stimulus that arises form stimulation from fixating eye (non-amblyopic eye) Goals 1. Differential diagnosis 2. Improvement of amblyopia 3. Elimination of suppression 4. Awareness or elimination of diplopia 5. Disruption of AC Mode of Action
- 17. Types of Occlusion Total or partial Conventional or Inverse Full time or Part time TOTAL PARTIAL (LIGHT TRANSMISSION) All light is prevented from entering the eye Doesn’t cut off the total light entering the eye Employed in amblyopic eyes with VA <6/24 Degrades the vision of normal eye such that amblyopic eye gets better vision and preference Occlusion using elastoplast, gauze pad, tape,doynes rubber occluder Occlusion using cellophane, transparent nail polish, or a higher plus lens
- 18. Partial / translucent occlusion Given in nystagmus Total Occlusion Amblyopia treatment
- 19. Conventional or Direct Inverse ● Occlusion of the sound eye ● Foveal or unsteady eccentric fixation is present in amblyopic eye ● Occlusion of amblyopic eye so that eccentric fixation becomes less fixed. ● Steady eccentric fixation ● Inverse occlusion is prescribed whenever occlusion is needed but direct occlusion is intolerable to the patient. ● Given only if the patient is strongly resistant to direct occlusion. ● Inverse occlusion is started first to introduce the hesitant patient to a patching regime. Example: A strabismus patient with deep amblyopia may not be able to perform needed visual tasks with amblyopic eye. So 1st inverse occlusion is started & changed to direct occlusion once more central fixation and improved visual acuity are obtained.
- 20. PART TIME (INTERMITTENT) ● Short time each day during close work commonly (1-6 hrs/day) ● In relapses after Rx and also for maintenance ● Given for intermittent strabismus or non strabismic amblyopes FULL TIME ● Removed only while going to bed at night (all waking hours) ● Choice of initial RX ● Given for constant strabismic amblyopes. (regardless of size of deviation) FULL TIME VS PART TIME
- 21. Some exceptions. . . ● CXT patients who change quickly to an intermittent strabismus with therapy, instead of full-time occlusion may need only part time occlusion or even no occlusion. ● Some strabismic amblyopes with dysfunctional BV may need minimal to no occlusion esp when amblyopia is treated actively with simultaneous improvement of sensorimotor processing. (Cohen 1981; Pickwell 1976) ● Intermittent strabismus or heterophoric patients with symptoms due to inefficient BV may need full time occlusion rather part time to allay binocular symptoms until BSV is improved. After recovery of symptoms, patching schedule is changed to part time. ● In infants & toddlers <2 yo, due to greatest plasticity in neural processing system to prevent occlusion amblyopia, maximum 2 hrs/day is given & passive lens, prism therapy is given together with active therapy.
- 22. Occlusion in Intermittent Strabismus ➢ Time of occlusion depends on patient’s level of sensorimotor skills. ➢ SInce constant occlusion may break down binocular skills only part time occlusion is recommended. ➢ When not wearing patch patient’s existing binocular skills can be reinforced through passive therapy & sensory anomalies such as suppression can be eliminated when wearing patch. ➢ In intermittent strabismus, part time occlusion eliminate central or foveal suppression and treat shallow amblyopia eye after binocularity is achieved. ➢ Nonstrabismic anisometropes or intermittent strabismics with deep amblyopia requires most hours of part time general occlusion ➢ Intermittent strabismics with good peripheral sensorimotor fusion and shallow or no amblyopia requires least hours of part time general occlusion.
- 23. Occlusion in Constant strabismus ➢ Earlier, full time occlusion followed by a day of rest was advocated. This allows constant strabismus to regress to anomalous strabismus visual processing on free day. ➢ Nowadays, full time occlusion is prescribed initially. When intermittency is achieved in open space, part-time occlusion is given allowing some reinforcement of binocular skills in normal activities.
- 24. Points on Occlusion ❖ The presence (or absence) of amblyopia and its fixation pattern determine which eye to patch. ❖ The frequency of strabismus determines the amount of time that the eye is patched Alternate occlusion ❖ When equal visual is present in each eye, (e.g. :- a constant alternate esotropia), full time occlusion is alternated daily between two eyes. ❖ The purpose of full time occlusion for strabismics with no amblyopia is to eliminate suppression and possibly disrupt anomalous correspondence.
- 25. Types of occluders ➢ Adhesive skin patches - made of microscope (best method) ➢ Commercially available opticlude ➢ Spectacle occluder - patched eye remains visible to observer, diffuse light enters occluded eye from unblocked sides around the frame. Child may look from top of glasses. Good cosmesis. ➢ Contact lens occluder - Opaque center on contact lens, total blockage of form and light, good cosmesis ➢ Bandage occluder - Total blockage of form and light, difficult to remove, greater chances of occlusion amblyopia, poor cosmesis
- 26. ➢ Tie-on occluder ○ Easily removed or flipped up ○ No skin problems as bandage ➢ Clip-on occluder ○ Attached to spectacle lens ○ Diffuse light enters as in spectacle occluders ➢ Occlusion filters for the treatment of suppression and amblyopia ○ Decrease both light and form transmission ○ Neutral density or red filters are placed before normal eye and are increased in density until fixation is forced to non preferred eye ➢ Occlusion lens - form recognition is reduced by lens induced optical blur a/k/a penalized lens or fogging lens
- 27. Field coverage ➢ Depends on how much of the visual field to block ➢ Either the visual stimulation is blocked to whole visual field (total occlusion) or just specific portions of the visual field (partial occlusion) (d/t presence and frequency of strabismus in a specific gaze or distance) ➢ Other consideration is whether to cover both peripheral and the central retina or just the central retina of the deviating eye.
- 28. Field Coverage Occluders Terminology Indication Visual Field Coverage Total Constant strabismus at all distances and gazes Full field Half-patch Constant strabismus at one distance and intermittent or heterophoria at other. Distance or near field Sector patches Incomitant strabismus. (intermittent in one field of gaze and constant in other) ● BSV remain in nonaffected and nonoccluded field ● Anomalous sensory processing can be disrupted or diplopia can be eliminated in affected field ● Achieve goal of binocular therapy sequence Selected gazes
- 29. ● Bipatches block the visual stimulation to a specific retinal region of nonfixating eye which under unoccluded conditions would receive anomalous visual stimulation d/t turning of eye. ● Both trigger alternation in viewing to amblyopic eye, leading to improved visual acuity or elimination of foveal suppression. ● Both are alternate to total occlusion. ● Bitemporal occlusion disturb panoramic vision. So, not much favoured. Terminology Indication Visual field coverage Binasal Constant Esotropia Nasal Fields (temporal retina) Bitemporal Constant Exotopia Temporal fields (nasal retina)
- 31. A simplified schedule for initial occlusion therapy for amblyopia Age of patient (in yrs) Period of occlusion (days) Direct vs Inverse Follow up after every Up to 2 2 : 1 15 days 3 3 : 1 15 days 4 4 : 1 1 month 5 5 : 1 1 month 6 or older 6 : 1 1 month
- 32. How to go about Occlusion 1. Compliance is the key. Motivation of child and parents is necessary. First the near vision then distance starts improving. 2. Active vision exercises by amblyopic eye has developed equal vision and equal preference of fixation. 3. May take 3-6 months 4. If there is no improvement, on three consecutive monthly follow-ups then treatment is stopped, reevaluation is advised. 5. Incomplete response to occlusion tends to be associated with anisohypermetropia & anisoastigmatism. 6. Follow-up depending on age, severity of amblyopia and compliance 7. To look for VA, fixation pattern and occlusion amblyopia 8. WHen to stop occlusion a. VA equals in both eyes b. Alternation of fiction (Repka 2008) 9. When VA is stable, patching may be decreased slowly. 10. Because amblyopia recurs is large number of points, maintenance therapy or tapering of therapy should be strongly considered.
- 33. Disadvantages of Occlusion 1. Occlusion amblyopia 2. Psychological distress 3. Allergic skin rash 4. Cosmetically unacceptable 5. Strabismic diplopia 6. Deviation changes https://www.slideshare.net/AayushChandan2/amblyopia-classification-occlusion-therapy-141098270
- 34. General Treatment Sequences for Accommodative and Nonstrabismic Binocular Vision Anomalies Occlusion - commonly used treatment option in the management of strabismus and its associated associated conditions: 1. Amblyopia 2. Eccentric fixation 3. Suppression 4. Anomalous correspondence There are also instances in which occlusion is necessary in the treatment of patients with heterophoria, and it must be included as part of the sequential considerations in the management of nonstrabismic binocular anomalies. Occlusion
- 35. Occlusion Occlusion - used when heterophoria is associated with anisometropic amblyopia. The length of occlusion is important in anisometropic amblyopia. Recommendations are based on randomized studies: 1. 2 hours of patching per day along with 1 hour per day of near visual activities for moderate amblyopia (20/30 to 20/80) 2. 6 hours per day with 1 hour per day of near visual activities for severe amblyopia (20/100 or worse) Scheiman, Mitchell; Wick, Bruce. Clinical Management of Binocular Vision (pp. 97-98). Wolters Kluwer Health. Kindle Edition.
- 36. Occlusion-Based Treatment (Without Active Vision Therapy) ➢ Reasons for poor image fusion may include asymmetries in image quality due to either refractive or organic dissimilarities. ➢ Difficulties in fine-motor control (as with hypotonia) may also thwart binocular fusion. In such situations, patients may learn to posture their eyes strabismically in order to remove the image conflict. ➢ Occlusion methods may be offered to provide an alternative means of reducing image conflict over areas of space. ➢ The following occlusion strategies may be applied in order to enhance binocular performance in patients with strabismus:
- 37. ➢ Occlusion - proposed as a nonsurgical treatment for young children with intermittent exotropia. ➢ Part-time occlusion - sometimes prescribed in young children until vision therapy is feasible, or to delay potential surgery. The reported potential benefits of patching include: ○ preservation of binocularity ○ reduction in the frequency and/or magnitude of the exodeviation. ➢ In a recent PEDIG study, the authors reported that deterioration of intermittent exotropia over a 6-month period was uncommon among children 12 to 35 months of age with previously untreated intermittent exotropia. The rate of deterioration 6 months after randomization was 2.2% for the patching group, and 4.6% for the observation group overall, or 2.3% for cases that met motor deterioration criteria, making it unlikely that part-time patching provides a meaningful short-term benefit for young children with intermittent exotropia.
- 38. ➢ In another PEDIG study of older children with intermittent exotropia, they evaluated the effectiveness of prescribing 3 hours of daily patching compared with observation alone for reducing the risk of deterioration of intermittent exotropia in previously untreated 3 to <11-year-old children. ➢ The rate of deterioration at 6 months post- randomization was low in both groups—only 0.6% in the patching group and 6.1% in the observation group deteriorated. Thus, deterioration of previously untreated childhood intermittent exotropia over a 6- month period is uncommon with or without patching treatment.
- 39. Regional occlusion Another type of occlusion that should be considered in heterophoria. This is particularly useful when a strabismus is present at one distance or one direction of gaze, while a heterophoria exists at other distances or positions of gaze. Example: Patient with a 25 Δ constant right XT at distance and a 5 Δ XP at near. Treatment: Occlusion of the upper portion of the lens of the right eye, with the lower portion of the lens clear. **This setup permits reinforcement of binocularity at near, while preventing suppression and other adaptations at distance.
- 40. 1. Binasal occlusion ➢ Binasal (or uninasal) occlusion is a highly effective means of reducing the angle of strabismus in a variety of postures for the same basic reason: it masks the area over which both eyes provide conflicting image information. ➢ By masking the nasal visual fields, binasal occluders reduce the visibility of the binocular visual field. Each eye has ipsilateral access to its temporal visual field. The binocular field is reduced to a narrowed strip, reducing the visual field area over which there is a perceived conflict. Fig 24.7, the preferred OD is masked more than OS
- 41. ➢ With binasals, each eye can offer novel information, but neither eye can provide visual input on the full field. This encourages the two eyes to team up and to orient forward for the most consistent acquisition of visual information when walking. ➢ In order to encourage flexibility in fixation preference, binasal occlusion thickness can be applied asymmetrically. Alternating thickness application at subsequent visits can help to disembed head posture adaptations and increase visual exploration as eye- teaming develops. Fig 24.7, the preferred OD is masked more than OS
- 42. ➢ Binasals encourage the use of an amblyopic and/or esotropic eye in its temporal field. ➢ Binasals can reduce the fusion demand in exotropia, providing a benefit to having both eyes orient toward primary gaze and fuse the two images along the midline. ➢ Binasals disrupt the suppression tendency in hypertropia, providing an incentive for the eyes to level and to generate a uniform horizon across the midline. Reach and grasp to encourage movement. Note the change in binasal placement relative to the photo above. https://www.youtube.com/watc h?v=nUpBd31JEuc
- 43. Reach and grasp to encourage movement. Note the change in binasal placement relative to the photo above. https://www.youtube.com/watc h?v=nUpBd31JEuc ➢ In a novel study of the impact of binasals on patients with traumatic brain injury (TBI), binasal occlusion was shown to improve the amplitude on visually evoked potential (VEP) testing, with a presumed mechanism of alleviating the need for suppression over an area of visual motion sensitivity. ➢ A similar mechanism would reduce the need for suppression with visual confusion or visual–spatial processing dysfunction.
- 44. 2. Spot occlusion 1. In patients whose conflict arises from an organic difference in image quality, spot occlusion may offer a means of dampening the central/distorted image while enabling access to the peripheral orienting information from both eyes. 2. Spot occlusion is particularly helpful in cases where medically induced differences in image quality disrupt the preferred eye.
- 45. Applying Occlusion 1. Occlusion can be created by applying a small piece of translucent tape, a piece of a Bangerter foil, or clear nail polish, stippling it with the brush and adding a second coat for a smoother surface that remains optically irregular. 2. Binasal occlusion thickness recommendations vary. It is important to recognize that the spectacle plane rests in front of the eye. From that location, setting the occlusion as a narrow strip, covering only to the medial canthus, is often sufficient, while still allowing a fusible binocular zone. A slightly wider placement is sometimes suggested over the preferred eye and may help to switch a dominance pattern for young children.
- 46. 3. Applying nasal occlusion temporal to the nasal iris limbus is less well-tolerated. Once the occlusion is placed, assess the placement by observing the patient’s tracking patterns as they follow a target across midline. 4. In patients with strabismus, adjust the location of the occluders to help the patient switch fixation within 5 to 10 degrees of midline, whether tracking left-to-right or right-to- left.
- 48. TUESDAY = 50 - point Quiz COVERAGE: Unit 4.1 General Treatment Strategy Unit 4.2 Lens Therapy Unit 4.3 Prism Therapy Unit 4.4 Occlusion Therapy
Editor's Notes
- #7: transient strabismus (either due to denervation or decompensated paresis)
- #15: https://www.slideshare.net/AayushChandan2/amblyopia-classification-occlusion-therapy-141098270
- #43: https://www.youtube.com/watch?v=nUpBd31JEuc
- #44: https://www.youtube.com/watch?v=nUpBd31JEuc