Fig.1 Young Girl 5-Year Old Treating of Amblyopia

Amblyopia

Amblyopia is a decrease of visual acuity without no causes can be detected by the physical examination of the eye. Poor vision caused by abnormal visual development secondary to abnormal visual stimulation. We use the term ”functional amblyopia “or “amblyopia ex anopsia” to refer to those conditions in which the visual acuity deficit is potentially reversible by occlusion therapy.Fig 1,2,3.

Fig.1 Young girl 5-year–old treating of amblyopia.

1.Strabismic amblyopia.

2.Anisometropic amblyopia.

3.Ametropic amblyopia

4.Deprivation amblyopia

5.Organic amblyopia

6.Amblyopia from nystagmus

STRABISMIC AMBLYOPIA Clinical findings:

 one eye strabismus

 amblyopia is unilateral

 constant suppression in deviated eye

 loss of binocularity

 occurs in 50% of patients with congenital strabismus

Investigation:  Hirschberg test

 positive cover-uncover test

 cycloplegic refraction

 loos of visual acuity in one eye

 eccentric fixation

 poorer contrast sensivity

 neutral density filter test

 stereopsis tests are negative

Differential diagnosis:  anisometropic amblyopia

 ametropic amblyopia

 deprivation amblyopia

 organic amblyopia

Treatment:  parent’s education and compliance is very important

 wearing apppropriate glasses

 occlusion the sound eye(Fig.1)

 penalization method

 pleoptics therapy

 Cam vision stimulator  surgical therapy after amblyopia is reversed

Prognosis:  if amblyopia is detected early ,the less dense it will be and the shorter period of occlusion will be needed to treat it

Anisometropic amblyopia

Clinical findings:  differences greater than +1,5Dsph of hypermetropia in both eyes

 sometimes in myopia -3,0Dsph differences between eyes

 differences about 2,0Dsph of astigmatism in each eyes

 amblyopia is unilateral

 occurrence of aniseikonia

 associated with strabismus in about 30%

Investigation:  cycloplegic refraction

 visual acuity

 crowding phenomen

 fixation pattern

 complete eye examination

 changes in binocular function and stereopsis

 the electrophysiological tests

Differential diagnosis:  strabismic amblyopia

 organic amblyopia Treatment:  wear a contact lenses is the best solution of anisometropia

 sometimes glasses and occlusion shold be prescribed

 agressive occlusion therapy(Fig.2)

 penalization metod in cases with small amblyopia

 Cam vision stimulator

 pharmacological modalities ( levodopa-carbidopa)

Fig.2.Application color contact lens to patch the sound right eye.

Prognosis:  vision screening program help of early detection

 agressive occlusion therapy in early ages is the most succesfull treatment

 child wearing the contact lenses can developed partial binocularity

 delay in treatment beyond the critical period results in irreversibility of amblyopia

Ametropic amblyopia This type of amblyopia is usually bilateral and is caused by an uncorrected refractive error. Clinical findings:  high refractive error in both eyes without appropriate correction  the patients with greater than 6 Dsph of hyperopia

 the patients with greater than 12 Dsph of myopia

 the patients with greater than 3 Dcyl of astigmatism

Investigation:  cycloplegic refraction

 complete eye examination

 visual acuity

 crowding phenomen

 fixation pattern is usually central

Differential diagnosis:  anisomertopic amblyopia

 strabismic amblyopia

Treatment:  appropriate glasses or contact lenses correction for wearing all day time

 occlusion the sound eye(Fig.3)

 Cam vision stimulator

 pharmacological modalities ( levodopa-carbidopa) Fig.2.One choose of application of a patch to the sound eye .

Prognosis:  ametropic amblyopia is ussually correctable by the wearing of appropriate glasses or contact lenses

 vision and refraction screening program help of early detection

 delay in treatment beyond the critical period results in irreversibility of amblyopia

DEPRIVATION AMBLYOPIA The main factor of deprivation amblyopia is the lack of stimulus of the retina. Clinical findings:

 unilateral or bilateral amblyopia

 this occurs in cases such as:

*congenital cataract

*corneal opacitates (Fig.4,5)

*vitreous hemorrhage

*complete ptosis Fig.4 Recurrent corneal erosion.

Fig.5 Leucoma cornea

Investigation:

 full ophthalmologic examination

 visual acuity

 cycloplegic refraction Differential diagnosis:

 anisomertopic amblyopia

Treatment:

 diagnosed and treated soon after the onset

 elimination any organic lesion

 full correction anisometropic eye with the contact lenses

 amblyopia treatment

Prognosis:

 if treated soon after the onset and patient have good anatomical condition it may be good

 optimum optical correction usually with contact lenses is very important

 occlusion is used for 80% of the waking day in a very young child can give good result

 visual rehabilitation is also important

Organic amblyopia This is a form of amblyopia that may be explained by existing structural lesions ,but that improves partially with treatment. Clinical findings:

 pathologic lesion affecting the fovea and surrounding retinal area such as:

*toxoplasmosis

*chorioretinitis

*retinoblastoma

*traumatic retinal lesion(Fig.6)

 abnormality of the visual pathway Fig.6The eye with traumatic retinal lesion

Investigation:

 cycloplegic refraction

 visual acuity

 full ophthalmologic examination

Differential diagnosis:

 anisomertopic amblyopia

Treatment:

 try occlusion of the better eye and see how the child responds

Prognosis:  prognosis must be very guarded

 early detection and treatment are essential for a successful outcome

Amblyopia from nystagmus Nystagmus is common with different grades of amblyopia. However we do not know if the reason for poor vision is due to nystagmus ,or if the amblyopia leads to the nystagmus.

References

1.Bradford GM, Kutschke PJ, Scott WE. Results of amblyopia therapy in eyes with unilateral structural abnormalities. Ophthalmology. 1992;99:1616-21. 2.Clarke WN, Noel LP. Prognostic indicators for avoiding occlusion therapy in anisometropic amblyopia. Am Orthopt J 1990;40:57-63. 3.Krzystkowa K.: Concomitant strabismus: Treatment of strabismus and amblyopia. In: Orłowski W (ed.): Modern ophthalmalmology ,PZWL, Warsaw 1992, vol. 3, p. 226-267. 4.Daw NH, Fox K, Sato H, Czepita D. Critical period for monocular deprivation in the cat visual cortex. J Neurophysiol. 1992;67:197-202. 5.Holmes JM, Beck RW, Repka MX, et al. The Amblyopia Treatment Study visual acuity testing protocol. Arch Ophthalmol 2001;119:1345-53. 6.Friden SJ, Kuperwaser MC, Stromberg AE, Goldman SG. Stripe therapy for amblyopia with a modified television gamę. Arch Ophthalmol. 1981;99:1596-9. 7.Fletcher MK, Abbott W, Girard LJ, et al. Results of the biostatistical study of the management of suppression amblyopia by intensive pleoptics versus conven-tional patching. Am Orthopt J. 1969;19:8-30 8.Gottlob I, Charlier J, Reinecke RD. Visual acuities and scotoma after one week lev-odopa administration in human amblyopia. Invest Ophthalmol Vis Sci. 1992;33:2722-28. 9.Pediatric Eye Disease Investigator Group. The clinical profile of moderate amblyopia in children younger than 7 years. Arch Ophthalmol 2002;120:281-85 10.Pediatric Eye Disease Investigator Group. A randomized trial of atropine vs patching for treatment of moderate amblyopia in children. Arch Ophthalmol 2002;120:268-78.

11.Pediatric Eye Disease Investigator Group. A randomized trial of prescribed patching regimens for treatment of severe amblyopia in children. Ophthalmology 2003;110:2075-87 12.Pediatric Eye Disease Investigator Group. A randomized trial of patching regimens for treatment of moderate amblyopia in children. Arch Ophthalmol 2003;121:603-11. 13.Moseley MJ. Neufeld M, McCarry B, et al. Remediation of refractive amblyopia by optical correction alone. Ophthalmic Physiol Opt 2002;22:296-9. 14..Kivlin JD, Flynn JT. Therapy of anisometropic amblyopia. J Pediatr Ophthalmol Strabismus 1981;18:47-56. 15. Laguire LE, Regan GL, Bremer DL, et al. Levodopa/carbidopa for childhood amblyopia. Invest Ophthalmol Vis Sci. 1995;34:3090-5. 16.Moseley MJ, Fielder AR. Irwin M, et al. Effectiveness of occlusion therapy in ametropic amblyopia: a pilot study. Br I Ophthalmol 1997;81:956-61. 17.Stewart CE, Moseley MJ, Fielder AR, et al. Refractive adaptation in amblyopia: quantification of effect and implications for practice. Br J Ophthalmol 2004;88:1552-6. 18.Moke PS, Turpin AH, Beck RW, et al Computerized method of visual acuity testing: adaptation of the Amblyopia Treatment Study visual acuity testing protocol. Am J Ophthamol 2001;132:903-9. 19.Lam GC, Repka MX, Guyton DL. Timing of amblyopia therapy relative to strabismus surgery. Ophthalmology. 1993;100:1751-6.. 20.. Krumholtz I, FitzGerald D. Efficacy of treatment modalities in refractive amblyopia. J Am Optom Assoc 1999;70:399-404. 21.Pediatric Eye Disease Investigator Group. A randomized trial of atropine regimens for treatment of moderate amblyopia in children. Ophthalmology 2004;111:2076-85. 22.Levitt FB, Van Sluyters RC. The sensitive period for strabismus in the kitten. Dev Brain Res. 1982;3:323-27. 22.Mehdorn E, Matthews W, Schuppe A, et al. Treatment for amblyopia with rotat-ing gratings and subseąuent occlusion: a controlled study. Int Ophthalmol. 1981;3:161-6.

23.Nucci P, Alfarano R, Piantanida A, Brancato R. Compliance in antiamblyopia occlusion therapy. Acta Ophthalmol (Copenh) 1992;70:128-31.

24.von Noorden GK, Campos EC. Binocular Vision and Ocular Motility: Theory and Management of Strabismus. 6th ed. St. Louis: Mosby; 2002:340-4.