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Rule #3. Jay C Bradley MD Sandra M Brown MD. Case. Chief Complaint: left eye crosses HPI 18 month old healthy girl Left eye crossing intermittently for 4-5 mos More noticeable when tired Worsening overall PMH Normal pregnancy, delivery, development. Family History. Bilateral OA.
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Rule #3 Jay C Bradley MD Sandra M Brown MD
Case • Chief Complaint: left eye crosses • HPI • 18 month old healthy girl • Left eye crossing intermittently for 4-5 mos • More noticeable when tired • Worsening overall • PMH • Normal pregnancy, delivery, development
Family History Bilateral OA Unable to drive legally; problem detected < 1st grade ?
Examination • Normal visual attention for age • Bruckner – large superior crescents OU • ITT • One refixation OD • No movement OS • Motility • Orthophoria at distance • Orthotropia with 8-10 PD esophoria at near • Versions full w/o oblique overaction
Penlight exam • Normal OU • Fundus exam • Small optic nerves with indistinct borders OU • Mild macular hypoplasia OU • Lightly pigmented throughout • Refraction • +5.50 + 1.00 x 95 OD • +6.00 + 1.00 x 90 OS
Hereditary Optic Nerve Atrophy • Bilateral gradual loss of central vision • VA 20/40 to 20/100 • Long term prognosis – rarely < 20/200 • Generally starts in first decade • Dyschromatopsia • Ceocentral or paracentral scotomas with preserved peripheral field initially
Optic discs • Temporal pallor • Triangular temporal excavation • Inheritance • Usually autosomal dominant • Occasionally autosomal recessive • Phenotype varies by rate of vision loss
Brown’s Rules of Pediatric Ophthalmology • #1 Don’t make the child cry • #2 Don’t let the child make you cry • #3 Everything in pediatric ophthalmology makes sense • Lee Jampol’s Clinic Rule • Try not to give the patient more than one disease
McCartney’s Rule • A patient may have as many diseases as they wish
All blonde Bilateral OA Unable to drive legally; problem detected < 1st grade ? ET Thick glasses
Albinism • Foveal hypoplasia • Critical clinical feature • Iris transillumination defects • Very difficult to detect in young kids • Minimal fundus pigmentation • Light-skinned • Doesn’t tan easily • “very light hair when young”
Sensory nystagmus • Foveal function in infancy < 20/200 OU • High hyperopia • Accommodative esotropia • Poor binocular stability • Abnormal ganglion cell decussation • Amblyopia
Racial Differences • Caucasians • Tyrosinase gene mutations • African Americans • Intermediate phenotype • P gene mutations
Always on the Boards • Chediak Higashi syndrome • White cell dysfunction • Recurrent infection • Hermansky Pudlak syndrome • Bleeding diathesis • Increased frequency in Puerto Ricans
“Old Style” Albinism Genetics Type Location Locus Gene Product Function OCA1 11q TYR Tyrosinase Enzyme OCA2 15q P P Protein Membrane OCA3 9q TYRP1 TYRP1 Enzyme OA1 Xp OA1 OA1 Protein Membrane HPS1 10q HPS1 HPS1 Protein Vesicle HPS2 5q ADTB3A B-3A-adaptin Vesicle CHS1 1q CHS1 CHS1 Protein Vesicle
New Thinking: Phenotype Spectrum “Chalky white” Acuity < 20/200 Sensory nystagmus “Ordinary” ~ 20/30
Leaky vs Non-Leaky Mutations • Leaky mutations • Some enzyme production • Non-leaky mutations • No enzyme production • OCA-1B no activity “chalk white” • OCA-1A partial activity “darkens down” • Mom + Dad = net enzymatic deficiency
Rule #3 • “Better Fit” Diagnosis – Mild Albinism • Fundus appearance • Hyperopia • Esotropia • Family history • pigmentation • “thick glasses” = high hyperopia • Esotropia
A Cruel Genetic Lottery • Might our patient have inherited AD optic nerve atrophy too? • Nothing rules it out. • Watch for disc pallor • Watch for decreased visual acuity resistant to refraction
Albinism Treatments • Glasses for refractive error • UV protection medically indicated • Patching for amblyopia • Atropine – must consider UV issues • Surgery for residual esotropia • Surgery for compensatory head turns • Education about sunblock • Education about genetics
Can This Get Better on Its Own? • YES! • Subset of patients with seemingly total foveal hypoplasia at < 1 yo • Gradual production of foveal pigment over first 5 years of life • Nystagmus slows down, might “stop” • Difficult to predict which kids will improve • Clinical observation: very smart kids
The Amarillo Effect • Many referrals for “can’t refract to 20/20” • Tow-headed kid and sibs/mom • Mild foveal hypoplasia • Normal “light end of spectrum” peripheral pigmentation for a Caucasian • Mild to moderate hyperopia • Not enough to cause bilateral amblyopia • Especially boys