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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 ? Thick glasses ET 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 OCA1 11q TYR Tyrosinase OCA2 15q P P Protein OCA3 9q TYRP1 TYRP1 OA1 Xp OA1 OA1 Protein HPS1 10q HPS1 HPS1 Protein HPS2 5q ADTB3A B-3A-adaptin CHS1 1q CHS1 CHS1 Protein Function Enzyme Membrane Enzyme Membrane Vesicle Vesicle Vesicle New Thinking: Phenotype Spectrum “Chalky white” “Ordinary” Acuity < 20/200 Sensory nystagmus ~ 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
