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A 25-month-old girl with vision loss, nystagmus, and anomalous head posture
Digital Journal of Ophthalmology 2009
Volume 15, Number 1
February 23, 2009
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Joel Metzger, MD | Senior Flight Surgeon, Training Air Wing Six, Pensacola, FL, USA Richard Hertle, MD | Children's Hospital of Pittsburgh, Pittsburgh, PA, UPMC Eye Center, Eye & Ear Institute, Pittsburgh, PA, and University of Pittsburgh School of Medicine, Pittsburgh, PA, USA John Avallone, MD | Ophthalmology Associates of Greater Annapolis Edward Cheeseman, M.D. | University of South Carolina School of Medicine, Charleston, SC and Uniformed Services University of the Health Sciences, Bethesda, MD, USA
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| Diagnosis and Discussion | The discovery of primary congenital glaucoma and decreased vision as the cause of an AHP and infantile nystagmus syndrome (INS) is unusual. Many disorders that affect vision and visual development in the first few weeks to months of life (e.g., cataracts, aniridia, achromatopsia and foveal hypoplasia) result in INS.(1-4) Despite the unusual presenting complaint, her exam was consistent with advanced primary congenital glaucoma. Goniotomy or trabeculotomy remains the preferred first surgical approach. Both procedures achieve greater than 80% success, but this number is markedly reduced in patients younger than 2 months or older than 2 years.(5) The use of drainage devices is reserved for difficult cases, where success rates may approach 95%.(5-7) Surgical success was achieved in this case with Baerveldt implants following failed trabeculotomies.
The reduction in the patient’s IOP to an acceptable range had profound effects on her vision and ocular anatomy. Her myopia was significantly reduced and the optic discs demonstrated reversal of cupping. This latter finding is common in congenital glaucoma and differentiates it from the adult glaucomas. As her vision improved the nystagmus and AHP decreased. The development of INS in this patient is a result of poor ocular motor calibration due to associated glaucomatous sensory system deficits (optic neuropathy, myopia, corneal irregularities and strabismus).
INS is the most predominant type of ocular oscillation associated with visual deprivation.(2,4,8) Although the exact etiology of INS is unknown, it likely caused by abnormal communication between the developing sensory and motor systems leading to a defect of ocular motor calibration. Patients with INS typically present with a horizontal nystagmus characterized by a slow and fast phase that increases in intensity with fixation and decreases with sleep, inattention or convergence. The oscillations change direction about a neutral position and a null point in eccentric gaze manifests as an AHP.(9) Diagnosis is confirmed by oculography that demonstrates waveforms having slow phases that display an increasing velocity exponential curve associated with periods of foveation. AHP is strongly associated with INS.(9) Treatment of AHP due to an eccentric gaze null zone associated with INS is directed towards returning the head to a more normal position and decreasing the intensity of the oscillation. In this case, treatment of the glaucoma, myopia and strabismus improved vision and resulted in a decrease in the nystagmus and the AHP. Recognition of congenital glaucoma in this patient who presented with new-onset nystagmus and AHP was essential in preventing eventual blindness. | |
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