2. Principles of non surgical treatment of strabismus
فروردین ماه 1390

3. The eyes As a sensorimotor unit
In this unitary sensorimotor system , the sensory system received about outside world
The motor system has no independent significance , is entirely in the service of the sensory system , and is largely governed by it .

4. The task of the Motor system
1- To en large the field of view 2- To bring the object of attention on to the fovea and keep it there 3- To position the two eyes in such a way that they are at all times properly aligned Maintaining Binocular vision

5. Deviations are either
1) Static – Mechanical 2) Dynamic – Inervational 3) Both

6. Mechanical deviation should be treated surgically and inervational factors nonsurgically for example – Refractive accommodative esotropia or convergence insuffigenly should never treated surgically.

7. Optical treatment
I . Refractive correction: A- Spectacles B- Prisms

8. Spectacles – corrective lenses Play two purposes
1- They create a sharp retinal image that is essential in young children 2- they assist in producing the proper balance between accommodation and convergence

9. Generally speaking
1- The full amount of the refractive error measured in cycloplegia 2- Young children normally will accept the correct glasses – if the mother reports that the child refuses to wear the glasses – it is not the fault of the patient In most instances it is the fault of ophthalmologist “hurting behind the ears or pinching the nose”

10. Full refractive correction should be prescribed from infancy through the preschool age regardless of the effect on distance vision this situation changes in older children.

11. In older children , distance Acuity is Essential in all activities
In older children , distance Acuity is Essential in all activities. Particularly in school situation About infants – glasses con be worn by babes in arms Don’t correct refractive errors less than +2.00D in infants The most important reason for prescribing glasses for infants is optical Astigmatic errors of ID or more and significant anisometropic errors should be corrected.

12. Bifocals
Bifocals are extremely valuable in the treatment of non refractive accommodative esotropia in a patient with a high AC/A Ratio. High AC/A Ratio Non refractive Accommodative esotropia Clinical characteristics N.R.A.E. is characterized by an esodeviation that is greater at near than at distance fixation

13. May occors in pts with Emmetropia Hyperopia Myopia Most frequently moderate hyperapia.

14. The effort to accommodates elicits an abnormally high accommodative convergence response.

15. Therefore the diagnosis of N. R. A. E
Therefore the diagnosis of N.R.A.E. is based on the PRESence of a significapt Esodeviation at near fixation on an accommodative fixation target with the refractive error fully corrected.

16. Therapy
Success of bifocal therapy is dependsnt upon the proper bifocal segment.

17. Small segments such as those used in presbyopia are useless in children

18. Separation line between distance and near segments bisects the pupil when the child looks straight ahead

20. We determine the power of bifocals by adding plus lenses to a clip – on frame attached to the patient's spectacles , starting with a D sph. And increasing the power in steps of Sph up to D sph

21. The effect of additional plus lenses on Esodeviation at near fixation cannot always be assessed immediately because the patient may be unable to sufficiently relax accommodation Paste on membrane lenses

22. Pharmacologic treatment of strabismus
I – Miotics therapeutic effect of miotics is based on A - facilitation of accommodation B - accommodative effort is reduced C – less accommodative convergence

23. So- The value of miotics in accommodative esotropia is obvious Short acting Two kinds of Miotics Long Acting

24. Short acting such as pilocarpine and eserine Longer acting such as : 1) Phospholine iodide “echothiophate iodide” 2) Humorsol

25. Phospholine iodide in o
Phospholine iodide in o.o6% solution on drop at bedtime starting with a week solution and using stronger concentration if the patient fails to respond.

26. Diagnostic trial
A diagnostic trial with miotics is indicated in esotropic infants to differentiate between non A. and refractive and nonrefractive A.Esotropia .

27. A significant re reduction of deviation at near identify patients who can be expected to benefit from a correction of hypermetropia refractive error from prescription of a bifocal Failure to respond to mitotic is a feature of non A.E

28. A – Therapy of Accommodative esotropia we prefer bifocals over miotics in long-range therapy of esotropia with a High AC/A Ratio . But miotics are used in children who will not tolerate glasses or unlikely to wear glasses for entire day or athletic activities during summer.

29. B _ Amblyopia – Occasionally we use mitotics in the amblyopic eye in combination with Atropinization of the sound eye . C – Myasthenia gravis – ocular Myasthenia in pts. In whom systemic medication has failed Side effects : A Potential risk exists when children who are on Miotic therapy undergo general anesthesia . Since cholinesterase is required for hydrolysis of succinylcholine .

30. Succinyl choline is a drug to facilitate intubation , so such patients may develop prolonged respiratory paralysis. 6 weeks prior to surgery phospholine iodide should be discontinued. Other systemic side effects of miotics are perspiration , Nausea , Vomiting , excessive salivation diarrhea and abdominal cramping Local effects 1- blurring of vision 2 – Iris cyst %

31. Phenylephrine used in combination with phospholin Iodide prevents iris cyst Iris cyst regress spontaneasly after discontinuation of phospholin ioded Other drugs: 1- Atropin 2 – Pharmacologic treatment with centrally acting drugs has remaineduninvestigated

32. f.e. Improvement of Esodeviation after systemic administration of chlordiazepoxide hydrochloride (librium).1mg /kg per day , then increased To 2 mg/kg especially for ACC.Esot. Dilatin & Reducing the AC/A Ratio

33. Botulinum toxin use in strabismus
_ BTX is an exotoxin produce by grame positive Bacteria “ Cholestridium Botulinum” _ This Bacteria produces 7 type of toxin (A-G) – we use A-B type in Ophthalmology BTX is a neurotoxin Agent which Acts in presynoptic cholinergic Nerve endings _ If drug resistance appear with type A , B type is used

34. Storage &Dosage Botox & disport are as a white powder add2cc normal saline to Botox and keep it in refigator for 4h – 14 days . Each 0.1cc contain 5 unit of Botox Add 2.5cc normal salin to dysport each 0.1 c.c. contain 20 unit of desport

35. Clinical indication of Botulinum Toxin
Indications of Btx – A in ophthalmology are : 1- Strabismus 2- Ocluoplastic

36. Strabismus indication of btx
There is limited studies about success full rate between strabismus surgery and btx injection at present time Injection of Btx in adultes is by local anesthesia and in children by general anesthesia In most of the patients , more than one Injection is necessary.

37. Route of injection A- directly into muscle B- subtenon injection Dosage – 0.5 – 0.1 c.c.in each injection

38. Use of Btx-A in strabismus
In adult with local anesthesia and in 1) Children with general anesthesia 2) Is a simple and fast technique 3) Several injection usually is needed 4) Sometimes , surgery is needed

39. Clinical indications
1- Congenital esotropia injection into two Medial Recti ( from 7 month to 18 month ) 2- Acquired Esotrpnia less then 30 D in all ages 3- Alternative exotropia- in two lateral Recti 4- In six nerve palsy: A- after 4 weeks if there is disturbing diplopia B- best results in six n palsy due to trauma

42. 5- in complete III N. palsy result is not satisfactory but in partial III N. palsy _ good result . 6- strabismus after retinal detachment surgery 7- in severe horizental strabismus “ D “ surgery in two muscles plus Btx –A injection 8- Nystagmous 9- Eyelid Retraction : 1) in thyroid ophthalmopathy 2) Idiopthic injection of 10 – 20 U. Disport into levator palpebral 3) For corneal protection

43. 10- Lacrimal Hypersecretion - crocodile tears: 10 – 20 U
10- Lacrimal Hypersecretion - crocodile tears: 10 – 20 U. of disport injection in palpebral lobe of lacrimal gland - orbital lobe injection is associated with high risk of diplopia

44. 1- Orthoptics 2- Treatment of functional amblyopia A- occlusion treatment B- Red filter treatment 3- Prisms recently – paper thin membrane Fresnel prisms became available. pasted to the back surface of spectacle lens. (up to 30 D )

45. Indications
1- maintain single comfortable binocular vision in the presence of Motor imbalance of the eyes 2- to modify eccentric fixation

46. 1- In therapy of heterotorpia – Horizental and vertical heterotorpia 2- nystagmus 3- Anomalies of vergence system 4- paralytic strabismus