Strabismus, Amblyopia & Leukocoria. Dr. Hessah Alodan, Pediatric Opthalmology Dept, KAUH. Why Two Eyes ?.
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Strabismus, Amblyopia & Leukocoria
Dr. Hessah Alodan,
Pediatric Opthalmology Dept, KAUH
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.
Left Eye Monocular
Right Eye Monocular
Total binocular field is nearly 170 degrees (varies according to configuration of orbits)
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
Action of extraocular muscles
Ocular misalignment due to abnormality in binocular vision or anomalies in neuromuscular control of ocular motility
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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
An amblyopic eye with 20/70 full line vision
may be able to see as well
20/30 viewing a single optotype
Alternation with alternate suppression avoids amblyopia
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
Bilateral Deprivation Amblyopia
Structural abnormalities of the retina or the optic nerve may be present. Functional amblyopia may be superimposed on the organic visual loss
Unilateral cataracts are usually isolated sporadic incidents
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
Arise in primitive photoreceptor cells.Characteristic histology:
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.
EMPIRICAL GENETIC COUNSELLING
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
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 fusiformaneurysmal dilations of the retinal vessels reminiscent of tiny light bulbs
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.
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.
RETINOPATHY OF PREMATURITY (ROP)
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.
Retinal detachment in childhood
retinal breaks or tears
retinal vascular disease
history of detachment in the other eye
Retinal detachment in childhood
flashes of light
curtain-like decrease in vision