1. Strabismus, Amblyopia & Leukocoria
Dr. Hessah Alodan,
Pediatric Opthalmology Dept, KAUH

2. Why Two Eyes ?
You can demonstrate to a patient the difference in their field or their child's field with one eye compared to two. With two eyes you can also demonstrate the peripheral field and the central fusion.

3. Why Two Eyes ? Left Eye Monocular Right Eye Monocular Binocular
Total binocular field is nearly 170 degrees (varies according to configuration of orbits)

4. Why Two Eyes ? Two Pencils Test
The same person with one eye closed or with manifest strabismus or no stereopsis will miss the examiner's pencil initially and place it correctly only after the second or third try.
With both eyes open the patient who uses both eyes producing stereopsis can put his pencil accurately on the examiner's pencil if stereopsis is present

5. Visual Axis Binocular Vision
Imaginary line between fovea and the object
Binocular Vision
If the visual axises from both eyes intersect at the object, binocular vision occurs

6. Sensory Fusion Motor Fusion
Supper imposed images from each corresponding retinal area in binocular cells at the level of the occipital cortex
Same images
Similar in size
Similar in clarity
Motor Fusion
Ability to physically move the eyes so that they are pointing in the same direction allowing the corresponding areas of the retina in each eye to be pointing at the object of regard

7. Visual Axes Misalignment lead to:
Confusion
Superimposition of the two different images stimulating corresponding retinal points
Diplopia
One object stimulating two none corresponding retinal points

8. Compensatory mechanism to misalignment of VA :
Suppression
Subconscious active neglect of one eye input that occurs only when both eyes are open
Amblyopia

9. Action of extraocular muscles
All obliques
Abduct
Horizontal Recti
Adduct 
All superior muscles 
Intort
 All inferior muscles 
Extort
Action
Muscles
    Dextroelevation 
OD: Superior Rectus OS: Inferior Oblique
  Dextrodepression
OD: Inferior Rectus    OS: Superior Oblique
    Levoelevation
OD: Inferior Oblique  OS: Superior Rectus
    Levodepression
OD: Superior Oblique  OS: Inferior Rectus
       Right gaze
OD: Lateral Rectus  OS: Medial Rectus
        Left gaze
OD: Medial Rectus  OS: Lateral Rectus

10. What is Strabismus ?
Ocular misalignment due to abnormality in binocular vision or anomalies in neuromuscular control of ocular motility

11. Classification of Strabismus:
According to fusion status
Phoria
Latent tendency of the eye to deviate and controlled by fusional mechanism
Intermittent Phoria
Fusion control is present part of the time
Tropia
Manifest misalignment of the eye all the time

12. Classification of Strabismus:
According to fixation
Alternating
Spontaneous alternation of fixation from one eye to the other
Monocular
Preference of fixation with one eye

13. Classification of Strabismus:
According to type of deviation
Horizontal
Esodeviation
Exodeviation
Vertical
Hyperdeviation
Hypodeviation
Torsional
Incyclodeviation
Excyclodeviation
Combined

14. Classification of Strabismus:
According to age of onset
Congenital
Acquired

15. Classification of Strabismus:
According to variation of the deviation with gaze position or fixing eye
Comitant
Same deviation in different direction of gaze
Incomitant
Variable deviation in different direction of gaze usually in paralytic or restrictive type of strabismus

16. Examination History Inspection Assessment of monocular eye function
Visual acuity
Preverbal children
CSM
OKN
Preferential looking
Visual evoked potential

17. Examination Assessment of monocular eye function Visual acuity
Verbal children
Symbol tests
Single illiterate E
Allen pictures
H O T V letters

18. Examination Assessment of binocular eye function Hirschberg test
Krimski’s test
Cover test
Alternate cover test
Prism cover test

19. Examination Fundoscopy Cycloplegic refraction Tropicamide
Cyclopentolate
Atropin

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34. Type of Strabismus Esotropia Pseudoesotopia Infantile esotropia
Accommodative esotropia
Partially accommodative esotropia

35. Pseudoesotropia
Occur in patients with flat broad nasal bridge and prominent epicanthal fold
Gradually disappear with age
Hirschberg test differentiate it from true esotropia

36. Infantile Esotropia
Common comitant esotropia occur before six month of age
Deviation is often large more than 40 prism diopter
Frequently associated with nystagmus and inferior oblique over action
Treatment
Correction of refractive error
Treat amblyopia
Surgical correction of strabismus

37. Accommodative Esotropia
Occur around 2 ½ years of age
Start as intermittent then become constant
High hypermetropia
Treatment
Full cycloplegic correction
Treat amblyopia

38. Partially Accommodative Esotropia
Improve partially with glasses
Treatment
Full cycloplegic correction
Treat amblyopia
Surgical correction of strabismus

39. Type of Strabismus Exotropia Intermittent exotropia Constant exotropia
Sensory exotropia

40. Intermittent exotropia
Onset of deviation within the first year of age
Closing one eye in bright light
Usually not associated with any refractive error
Usually not associated with amblyopia
Treatment
Correction of any refractive error
Surgical correction of strabismus

41. Constant exotropia
Maybe present at birth or maybe progress from intermittent exotropia
Treatment
Correction of any refractive error
Correction of amblyopia
Surgical correction of strabismus

42. Sensory exotropia
Constant exotropia that occur following loss of vision in one eye e.g trauma
Treatment
Correction of any organic lesion of the eye
Correction of amblyopia
Surgical correction of strabismus

43. Types of Strabismus Paralytic strabismus 6th nerve palsy
3rd nerve palsy

44. 6th Nerve Palsy Incomitant esotropia Limitation of abduction
Abnormal head position

45. 4th Nerve Palsy Congenital or acquired
Hypertropia of the affected eye with excyclotropia
Abnormal head position

46. 3rd Nerve Palsy Congenital or acquired
Exotropia with Hypotropia of the affected eye
In children caused by: trauma, inflammation, post viral and tumor
In adult caused by: aneurysm, diabetes, neuritis, trauma, infection and tumor

47. Special Types of Strabismus
Duane strabismus
Brown syndrome
Thyroid opthalmopathy

48. Duane Syndrome Limitation of abduction Mild limitation of adduction
Retraction of the globe and narrowing of the palpebral fissure on adduction
Upshoot or downshoot on adduction
Pathology faulty innervation of the lateral rectus muscle by fibers from medial rectus leading to co-contraction of the medial rectus and lateral rectus muscles

49. Brown Syndrome Limitation of elevation on adduction
Restriction of the sheath of the superior oblique tendon
Treatment needed in abnormal head position or vertical deviation in primary position

50. Thyroid Ophthalmopathy
Restrictive myopathy commonly involving inferior rectus, medial rectus and superior rectus
Patients presents with hypotropia, esotropia or both

51. Surgery of Extraocular Muscle
Recession : weakening procedure where the muscle disinserted and sutured posterior to its normal insertion

52. Surgery of Extraocular Muscle
Resection : strengthening procedure where part of themuscle resected and sutured to its normal insertion

53. Complication of Extraocular Muscle Surgery
Perforation of sclera
Lost or slipped muscle
Infection
Anterior segment anesthesia
Post operative diplopia
Congectival granuloma and cyst

54. Amblyopia

55. What is Amblyopia ?
Amblyopia refers to a decrease of vision, either unilaterally or bilaterally, for which no cause can be found by physical examination of the eye

56. Pathophysiology of Amblyopia
amblyopia is believed to result from disuse from inadequate foveal or peripheral retinal stimulation and/or abnormal binocular interaction that causes different visual input from the foveae
Cortical ocular dominance columns representing amblyopic eye less responsive to stimulus and show changes microscopically
Lateral geniculate layers subserving amblyopic eyes atrophic
Afferent pupil response has been reported but not common
No retinal changes - ERG OK

57. Amblyopia
Three critical periods of human visual acuity development have been determined. During these time periods, vision can be affected by the various mechanisms to cause or reverse amblyopia. These periods are as follows:
The development of visual acuity from the 20/200 range to 20/20, which occurs from birth to age 3-5 years.
The period of the highest risk of deprivation amblyopia, from a few months to 7 or 8 years.
The period during which recovery from amblyopia can be obtained, from the time of deprivation up to the teenage years or even sometimes the adult years

58. Amblyopia
Diagnosis of amblyopia usually requires a 2-line difference of visual acuity between the eyes
Crowding phenomenon: A common characteristic of amblyopic eyes is difficulty in distinguishing optotypes that are close together. Visual acuity often is better when the patient is presented with single letters rather than a line of letters
An amblyopic eye with 20/70 full line vision
may be able to see as well
20/30 viewing a single optotype
to 20/70

59. Causes of Amblyopia Anisometropia
Many causes of amblyopia exist; the most important causes are as follows:
Anisometropia
Inhibition of the fovea occurs to eliminate the abnormal binocular interaction caused by one defocused image and one focused image.
This type of amblyopia is more common in patients with anisohypermetropia than anisomyopia. Small amounts of hyperopic anisometropia, such as 1-2 diopters, can induce amblyopia. In myopia, mild myopic anisometropia up to -3.00 diopters usually does not cause amblyopia.

60. Causes of Amblyopia Strabismus
The patient favors fixation strongly with one eye and does not alternate fixation. This leads to inhibition of visual input to the retinocortical pathways.
Incidence of amblyopia is greater in esotropic patients than in exotropic patients
Alternation with alternate suppression avoids amblyopia

61. Causes of Amblyopia Visual deprivation
Amblyopia results from disuse or understimulation of the retina. This condition may be unilateral or bilateral. Examples include cataract, corneal opacities, ptosis, and surgical lid closure
Deprivation Amblyopia
Bilateral Deprivation Amblyopia

62. Causes of Amblyopia Organic
Structural abnormalities of the retina or the optic nerve may be present. Functional amblyopia may be superimposed on the organic visual loss

63. Causes of Amblyopia Ametropic Amblyopia
Uncorrected high hyperopia is an example of this bilateral amblyopia.

64. Treatment
The clinician must first rule out an organic cause and treat any obstacle to vision (eg, cataract, occlusion of the eye from other etiologies).
Remove cataracts in the first 2 months of life, and aphakic correction must occur quickly
Treatment of anisometropia and refractive errors must occur next
The next step is forcing the use of the amblyopic eye by occlusion therapy

66. Leukocoria

67. Causes of Leukocoria Cataract Retinoblastoma Toxocariasis
Coat´s disease
ROP
PHPV
Retinal detachment
Coloboma
Retinal dysplasia
Norrie´s disease

68. cataract opacification of the lens.
Congenital cataracts usually are diagnosed at birth.
If a cataract goes undetected in an infant, permanent visual loss may ensue.

69. Unilateral cataracts are usually isolated sporadic incidents

70. Bilateral cataracts are often inherited and
Bilateral cataracts are often inherited and associated with other diseases.
They require a full metabolic, infectious, systemic, and genetic workup.
The common causes are hypoglycemia, trisomy (eg, Down, Edward, and Patau syndromes), myotonic dystrophy, infectious diseases
(eg, toxoplasmosis, rubella, cytomegalovirus, and herpes simplex [TORCH]), and prematurity

71. RETINOBLASTOMA
Retinoblastoma is the most common intraocular tumor of childhood.
CLINICAL
MANIFESTATIONS
Leukocoria (60%)
Strabismus (20%)
OTHER- Uveitis, Orbital cellulitis, Hyphaema, Heterochromia, Glaucoma, Bupthalmos

72. RETINOBLASTOMA

73. Retinoblastoma
The disease is bilateral in approximately 30% of cases. The average age at diagnosis is 18 months and 90% of patients are diagnosed before the age of 3 years. Less than 10% of retinoblastoma suffers have a family history of the disorder, 90% of cases are sporadic. Of the sporadic cases, the responsible mutation is in a germ cell in 25% of cases and in a somatic cell in 75% of cases

74. GENETICS
Retinoblastoma gene is a recessive oncogene of 180,000 kilobases.
Located chromosome- 13q14
Knudson two hit hypothesis:
Germinal cells have one defective and one normal RB gene.
A somatic mutation results in loss of the normal RB gene and hence retinoblastoma develops (somatic mutations occur frequently enough in the developing retina, therefore lesions usually affect both eyes)
In addition, the first child of a parent who had had a unilateral retinoblastoma has a 4% chance of developing the disease

75. PATHOLOGY
Arise in primitive photoreceptor cells.Characteristic histology:
Retinoblastomas are composed of poorly differentiated neuroblastic cells with scanty cytoplasm and prominent basophilic nuclei.
The tumour proliferates rapidly, with a tendency to outgrow its blood supply and undergo spontaneous necrosis. Necrotic tumour being eosinophilic stain pink.
Characteristic Flexner-Wintersteiner rosettes represent an attempt at retinal differentiation. Histologically, a ring of cuboidal cells is seen surrounding a central lumen. Cuboidal tumour cells with basally oriented nuclei arranged around a central lumen.

76. Retinoblastoma
Calcification is another feature of retinoblastomas, usually occurring in necrotic areas. Calcium stains with H&E. It is worth identifying calcium in suspect eyes by ultrasound, or CT scan to differentiate retinoblastomas from other tumours.

77. MANAGEMENT EMPIRICAL GENETIC COUNSELLING ENUCLEATION
unilateral, poor visual prognosis
PLAQUE
4-12mm +/- vitreous seeding
EXTERNAL BEAM
>12mm, multiple foci, only eye
LASER
consider- indirect, xenon arc
cryotherapy if <2dd in size
CHEMOTHERAPY, if intracranial extension

78. Non-Retinoblastoma Malignancies
Unfortunately, children who have genetic retinoblastoma and survive their primary intraocular cancer have a substantially increased risk of death from one or more nonretinoblastoma malignancies over the course of their lifetimes, up to 35% of children who have had a bliateral retinoblastoma and external beam radiation therapy will develop a second cancer by age 25 years

79. Congenital retinal telangiectasis (Coats' disease)
Congenital retinal telangiectasis (Coats' disease) is an idiopathic retinal vascular disorder that usually affects young male patients unilaterally in their first or second decade of life.. Patients may present with decreased vision, as well as strabismus or leukocoria in children. The hallmark feature of congenital retinal telangiectasis is localized fusiform aneurysmal dilations of the retinal vessels reminiscent of tiny light bulbs

81. Persistent hyperplastic primary vitreous (PHPV)
Persistent hyperplastic primary vitreous (PHPV) is a congenital anomaly in which the primary vitreous fails to regress in utero. Highly vascular mesenchymal tissue nurtures the developing lens during intrauterine life. In PHPV, the mesenchymal tissue forms a mass behind the lens.

82. Persistent hyperplastic primary vitreous (PHPV)
A gray-yellow retrolental membrane may produce leukocoria, with the subsequent suspicion of retinoblastoma.
In PHPV, the globe is white and slightly microphthalmic. Patients have no history of prematurity or oxygen administration.

84. RETINOPATHY OF PREMATURITY (ROP)
Vasoproliferative retinopathy affecting premature infants exposed to high oxygen
INCIDENCE
Prematurity (<32/40)
Birth weight (30% < 1000gm affected)
Oxygen duration
90% ROP regresses spontaneously, 5% blindness

85. RETINOPATHY OF PREMATURITY (ROP)
Signs include:
neovascularization,
fibrous bands
retinal detachments
vitreous hemorrhage
leukocoria

87. Retinal detachment in childhood
Retinal detachment in childhood can be confused with retinoblastoma, and vice versa. The possibility of an underlying retinoblastoma should always be considered when a child presents with retinal detachment and vitreous hemorrhage, even when a history of trauma is obtained.

88. Retinal detachment in childhood
Risk factors:
Trauma
Surgery
vitreous detachment
high myopia
retinal breaks or tears
retinal vascular disease
history of detachment in the other eye

89. Retinal detachment in childhood
Symptoms
flashes of light
floaters
curtain-like decrease in vision

90. COLOBOMA Optic Disc Coloboma
Due to failure of closure of foetal fissure inferiorly
May be isolated disc or associated chorioretinal coloboma
Usually sporadic, some AD
Can be bilateral
Visual acuity varies from normal to NPL.