Evolution of drusen of the optic nerve head over 23 years (2008)

At the age of 4 years, an otherwise healthy girl was diagnosed with hyperopia, left amblyopia and convergent strabismus. She was treated over 4 years by the same ophthalmologist in private practice. A routine check-up at the age of 8 years revealed that her previously normal optic nerve heads had become swollen and she was referred to the local paediatric hospital for a neurological work-up. Clinically, the subject appeared to be in excellent health, but she stated that she had suffered some mild spells of headache during the preceding month. A plain skull X-ray showed pineal calcifications and the patient was referred for a neurosurgical evaluation at the university hospital. An in-house ophthalmological examination confirmed the diagnosis of bilateral papilloedema. Manual perimetry showed some concentric contraction bilaterally. Air and isotope encephalograms were obtained. Both turned out to be normal. Modern neuro-imaging was not available at this time, in 1973. Follow-up was taken over by the author. Review of fundus photographs taken during the hospital stay confirmed elevation of the nerve heads. There was little difference between the two sides: the following presentation concentrates on the right eye. There was slight scalloping of the nerve head border, most clearly between 12 and 1 o'clock (Fig. 1, top left). The retinal nerve fibre layer was difficult to evaluate just outside the swelling because of the superpositioning of a bright, ring-shaped reflex, but it appeared to lack the subtly unruly patterning that commonly occurs with raised intracranial pressure. The upper arcuate nerve fibre bundle appeared somewhat thinner than the lower one, indicating the likely presence of a lower arcuate or nasal field defect. The major retinal vessels showed an anomalous branching pattern, with compatible diameters. A small vascular loop was present at 9 o'clock. The overall picture was considered strongly suggestive of buried drusen, without signs of increased intracranial pressure. Neither the parents nor the sole sibling had funduscopic signs suggestive of either buried or exposed drusen. Collage of fundus photographs in the right eye collected over 23 years, adjusted to uniform magnification. The subject's age at the time each photograph was taken is inset. The patient was seen repeatedly over 23 years. There was unequivocal exposure of drusen at the age of 11 years (Fig. 1, top right), 3 years after the debut of nerve head swelling, at which time the bright peripapillary ring reflex had become fragmented. There followed a progressive exposure of drusen and loss of retinal nerve fibre bundles. By the age of 14 years, the central-most parts of the central retinal vessels had become obscured by an overlying opacity. One year later, a haemorrhage appeared in the same area, in close proximity to the temporal vascular loop. The loop was not discernible in later photographs. The peripapillary ring reflex was gradually replaced by a greyish discoloration of the peripapillary region. The evolution appeared nearly complete when the subject was 16 years of age, after 8 years of follow-up. When she was last seen, at the age of 31 years, there was no discernible change in fundus appearance. The patient was left with severely contracted visual fields but there was little change in acuity, from an original 0.8 decimal in the non-amblyopic right eye, to 0.65. Although she was dependent on public assistance for transportation, the patient was gainfully employed as a librarian, working half-time. Her general health had remained good through the years. With an estimated clinical prevalence of 0.3%, drusen or hyaline bodies of the optic nerve head, are fairly common and have been well described (for modern reviews, see Auw-Haedrich et al. 2002; Davis & Jay 2003). However, opportunities to document the full panorama of drusen evolution in a particular patient are exceedingly rare. The collage of photographs presented here confirms and extends the observations reported by Spencer et al. (2004). Nevertheless, there remains an important gap in the mapping of drusen evolution, namely, the objective documentation of the appearance of the nerve head prior to the debut of swelling. In the present case, nothing remarkable was noted by an experienced clinician during the 4 years of observation that preceded the appearance of swelling, but photography, had it been available, might have provided details capable of predicting what was to come. Knowledge of the very first events in drusen evolution should help to prevent the frequent misdiagnosis of papilloedema from raised intracranial pressure, thus saving both anxiety and the costs of work-up. Such knowledge would also be useful in the ultimate funduscopic challenge: to recognize true papilloedema superposed on buried drusen. An instrumental diagnosis of drusen of the optic nerve head can be obtained in several ways. B-scan echography may be the technique of choice, closely followed by computed tomography (Kurz-Levin & Landau 1999). Both techniques typically show localized bright spots, attributable to high acoustic reflection and high attenuation, respectively. These features reflect a high content of calcium or iron, or both. Simultaneous estimation of the width of the optic nerve sheath should allow recognition of the combination of true papilloedema and drusen (Newman et al. 2002).