Strabismus: What you need to ask and know

1. Strabismus: What you need to ask and know Lan Chang, MD Pediatric Ophthalmology and Adult Strabismus Eye Associates of New Mexico Disclosure: I, or a member of my family, or my professional partnership or corporation, or my employer, or co-instructor(s) / co-author(s), currently or within the preceding twelve (12) months have NOT  had a financial interest in a Designated Company, or a financial relationship, or advisory capacity with any Designated Company or entity related to my presentation.

2. Summary • Types of strabismus • Testing used to diagnose • Motility • Cover-testing • Double Maddox Rod testing • Worth-4-dot testing • Treatments including surgical vs. non-surgical • Glasses • Patch • Botox • Surgery

3. A Common Problem • 4% of the population affected

4. Causes • Eye misalignment is due to poor muscle control, can be due to problems with: • Eye muscles • Nerves that transmit information to the muscles • Control center in the brain that directs eye movements

5. Types Exo- (X), eso- (E)

6. Pseudostrabismus • Children have flat nasal bridges and prominent epicanthal folds • May be asymmetric • Eye appears esotropic • To differentiate: • Corneal light reflexes • Cover testing • Refer anyway? • Some later develop true strabismus

7. Normal Esotropia Exotropia Evaluation of Corneal Light Reflex • Hold small, bright light source near your own eye • Aim light at child's eye • Attract child's attention • Inspect the light reflection • Compare with center of pupil • Evaluate centration and symmetry • Ignore appearance of sclera

8. Types Exo- (X), eso- (E) Hypo- (hypo), hyper- (H)

9. Types • Exo- (X), eso- (E) • Hypo- (hypo), hyper- (H) • –phoria (), -tropia (T) • E vs. ET • X vs. XT

10. Types • Exo- (X), eso- (E) • Hypo- (hypo), hyper- (H) • –phoria (), -tropia (T) • Constant vs. Intermittent • XT vs. X(T)

11. Types • Exo- (X), eso- (E) • Hypo- (hypo), hyper- (H) • –phoria (), -tropia (T) • Constant vs. Intermittent • XT vs. X(T) • ET vs. E(T)

12. History for Evaluation of Strabismus Onset: when did it start (gradual or sudden) Provocation/Palliation: what makes it worse/better Quality: monocular/binocular, any shadow or star-burst Related symptoms or medical conditions: any head turn, any nystagmus, any ptosis, specifically ask about thyroid diseases for adults Strabismus history: any history of strabismus in family members or prior history of ocular surgery Trauma history: head/eye trauma

13. Differences between Children and Adults • In children: • Typically do not develop diplopia (suppress one eye) • Need treatment for amblyopia first if younger than 8 • Early surgery may be recommended to improve the chance of restoring or promoting normal binocular vision • In adults: • Often have double vision because their brains have already learned to receive images from both eyes and cannot ignore the image from the deviating eye • Surgery needs to wait until stability is established

14. Examination BCVA, MRx, check for prisms in glasses (mark optical centers)

15. Motility

16. Stereopsis Very important to access A test of binocular vision

17. Worth-4-Dot Diplopic vs. Suppression vs. Fusion (5 dots) (2 red or 3 green) (4 dots)

18. Double Maddox Rod A test of torsional diplopia

19. Treatment is Not Just Cosmetic • There are many other benefits beyond restoring normal appearance: • improved depth perception or binocular vision • improved visual fields • eliminating or minimizing double vision • improved social function — as eye contact is hugely important in human communication

20. Treatment—glasses Works well for high hyperopes with accommodative esotropia Important to perform cycloplegic refraction, especially in children Use cyclopentolate 1% for cycloplegia in children

21. Treatment—patching Alternate patching for intermittent exotropia X(T), may help with control and prevent amblyopia Rarely cures the condition

22. Treatment—eye exercises Exercises have been proven to treat convergence insufficiency

23. Treatment—prisms A good option for small misalignment Fresnel (temporary/Press-on) prism does blur vision slightly, good for trial and for double vision that may resolve Large correction results in significant decrease in quality of vision When building into glasses, try to balance between the eyes, bifocals are preferred over progressives.

24. Treatment—Botox Dr. Alan Scott is a pediatric ophthalmologist First FDA-approved for strabismus (1989) Onset of effect (1-2 days), peak effect (starting 1-2 weeks), duration of effect (3-4 months) Sometimes the effect on eye alignment can be long lasting Can be used alone or as augmentation to surgery

25. Using Botox for Strabismus • Candidates: • Patients with developmental delays, neurological strabismus, or borderline surgical candidates • Small-to-moderate angle of ocular misalignment • Good baseline visual acuity • Presence of (or potential for) stereopsis or fusion Before After

26. Treatment—surgery The muscle is then weakened, strengthened or moved (transposed) to change its action with dissolvable sutures Transposition Resection Recession

27. Adjustable Sutures After the surgery, with the patient awake, alignment can be reassessed, and if necessary, adjustments can be made, this minimize the chance of an over-correction or under-correction Achieve desired result with fewest procedures

28. Ideal Candidates for Adjustable Sutures • Restrictive strabismus • Graves, scleral buckle, anesthetic myotoxicity • Scarring from trauma or previous surgery • Any patient with several previous operations • Slipped, lost and disinserted muscles • Incomitant deviations • Duanes, myasthenia, paretic • Combined vertical, torsional, and horizontal deviations • Large or small eyes

29. Adjustable Sutures Dr. Chang’s preferred technique Minimally invasive and adjustment can be done within 1 week

30. Video 1: procedure

31. Healing of the Eyes Gradual healing occurs over several months, but even within a few days, there should be improvement in alignment and redness

33. Thank You! • Questions? • Acknowledgement: • Dr. David Hunter, MD/PhD for the use of his surgical video and patient photographs from his book, “Learning Strabismus Surgery”