From the 2nd Department of Ophthalmology (IE, VG, PN, GPT), Henry Dunant Hospital; the 2nd Department of Ophthalmology (IV, PT), Athens University; and Ophthalmiatrio Athinon Hospital (IH), Athens, Greece.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to George P. Theodossiadis, MD, 13 Lykiou Street, 10674, Athens, Greece.
Optic nerve head drusen are common, affecting 0.5% to 2% of the population. There is no sex predilection. Patients with optic nerve head drusen are often asymptomatic, but progressive visual field loss and vascular complications, including anterior ischemic optic neuropathy and choroidal neovascularization, may occur. In the absence of such complications, visual field defects may be of diverse severity and are believed to be progressive over the years1 in conjunction with nerve fiber layer loss.2 Inferior arcuate loss, generalized constriction, and blind spot enlargement constitute the most common patterns of visual field defects. In the presence of optic nerve head drusen, co-existence of raised intraocular pressure (IOP) poses a diagnostic dilemma as to whether the field defects represent glaucomatous damage or are associated with the primary pathology of papillary drusen.
We report a case with optic nerve head drusen, normal IOP, and gradual deterioration of visual field defects after a long follow-up period of 25 years, which failed to give reliable results on optical coherence tomography (OCT).
A 65-year-old woman was first examined in 1982 elsewhere and was found to have bilateral optic nerve head drusen. Goldmann kinetic perimetry showed inferior defects in both eyes that were more pronounced in the right eye. IOP was 15 mm Hg in the right eye and 14 mm Hg in the left eye.
When she was referred to our department in 1997, her visual acuity was 20/20 in each eye. A B-scan, red-free photography, and fluorescein angiography confirmed the existence of bilateral calcified drusen in the optic disc and in the peripapillary area (Fig. 1). The macula appeared normal on biomicroscopy and fluorescein angiography.
Figure 1. Color Photographs of the Optic Disc Drusen. (A) Right Eye. (B) Left Eye.
The patient had annual visual field analysis with automated static perimetry (Humphrey Allergan Instruments, San Leandro, CA) with excellent reliability indices. The visual field of the right eye showed a dense inferior arcuate scotoma that also extended to the superior nasal periphery. The visual field of the left eye disclosed a less dense inferior scotoma. The recorded defects closely matched those mapped with the Goldmann perimeter. The visual field defects showed progression on serial analysis during the follow-up period, although her IOP without treatment did not exceed 16 mm Hg in either eye. The scotomas in both eyes became denser and extended closer to the fixation point, mainly inferiorly but also in the superior periphery (Fig. 2).
Figure 2. The Gradual Deterioration of Kinetic and Automated Perimetry in Both Eyes During the Follow-Up Period Is Evident. The Visual Field Changes Are More Prominent in the Right Eye Due to the Extension of the Drusen Beyond the Optic Disc Margin. (A) Right Eye. (B) Left Eye.
OCT evaluation was performed with the OCT-3 (Zeiss Humphrey Instruments, Dublin, CA) in 2002 using the retinal nerve fiber layer thickness 3.4 protocol. The raised areas of high reflectivity depicted at the circular scan of 3.4-mm diameter, with their corresponding choroidal shadowing, represent the disc drusen that extend to the peripapillary area (Fig. 3). Because of these artifacts, reliable measurements of the nerve fiber layer thickness could not be made. Initial average nerve fiber layer thickness was 96.17 μm in the right eye and 116.42 μm in the left eye, whereas final average nerve fiber layer thickness of the right and left eyes was 94.69 and 113.28 μm, respectively. There was no significant decrease of the nerve fiber layer thickness between 2002 and 2007 (Fig. 4). At the first OCT examination in 2002, the macular thickness was 160 μm in the right eye and 165 μm in the left eye.
Figure 3. Optical Coherence Tomography Scans Depicting the Nerve Fiber Layer Thickness Around the Optic Disc. (A) Right Eye. (B) Left Eye.
Figure 4. Graph Showing the Change of Nerve Fiber Layer Thickness Between 2002 and 2007 (purple Line = 2002, Blue Line = 2007). (A) Right Eye. (B) Left Eye. TEMP = Temporal; SUP = Superior; NAS = Nasal; INF = Inferior.
During the follow-up period, the patient did not develop any macular cause of visual loss related to optic nerve head drusen, such as subretinal neovascular membrane, subretinal hemorrhage, or ischemic optic neuropathy, that could be responsible for the deterioration of visual fields.
Optic disc drusen may be “buried” deeply within a normal-appearing optic nerve head, may be visible as discrete crystalline structures, and may also extend beyond the margins of the optic nerve head in the peripapillary area.
The association between the peripapillary nerve fiber layer thickness and optic nerve head drusen is controversial. OCT examination in 7 eyes with optic nerve head drusen has shown thinning of nerve fiber layer thickness in all quadrants, especially inferiorly and superiorly.3 Thinning of the nerve fiber layer thickness, mainly inferiorly and superiorly, has also been described by Roh et al., who found visual field defects and nerve fiber layer loss in cases with clinically visible optic nerve head drusen.4 Other OCT reports support the view that the presence of optic nerve head drusen was found to have no effect on nerve fiber layer thickness in a follow-up period ranging between 14 and 22 months.5 Moreover, eyes with buried optic nerve head drusen may have focal nerve fiber layer defects but with normal average nerve fiber layer thickness.6
In our case, OCT showed an unusually thick retina around the optic disc with an uneven inner retinal surface and spikes extending into the vitreous cavity. In an effort to map those areas to the optic nerve head, we examined the OCT findings in relation to the color and red-free photographs of both optic nerve heads. Because of the unusual appearance and thickness of those areas, it is difficult not to relate them to the drusen. Therefore, it is not possible to safely extract any conclusion as to the real thickness of the nerve fiber layer. Even though there have been described cases with optic nerve head drusen where OCT showed changes in the nerve fiber layer thickness,3,4 in our patient the nerve fiber layer thickness could not be measured accurately due to the extension of the optic nerve head drusen in the peripapillary area. The more peripheral extension of the OCT scan circle would provide more reliable measurements of the nerve fiber layer thickness, but the lack of normograms out of the 3.4-mm diameter circle may compromise its significance in assessing it as normal.
On biomicroscopy, the macular area appeared normal. At the first OCT examination in 2002, the macular thickness was 160 μm in the right eye and 165 μm in the left eye. For this reason, no further examination of the macular thickness was done, although it has been reported that macular thickness changes could be correlated with changes in nerve fiber layer structure in glaucoma and may be a surrogate indicator of retinal ganglion cell loss.7
Although OCT was not helpful, serial analysis of the automated visual fields that were performed on an annual basis in the period between 1997 and 2007 shows a progression of the scotomas, which were plotted originally with kinetic perimetry. The latest visual field tests, performed in June 2007 (25 years later than the original Goldmann visual field) demonstrate a remarkable constriction that was not associated with any vascular complications related to optic nerve head drusen.
Several authors reported visual field loss in patients with optic nerve head drusen, depending mainly on the age and the depth of the drusen within the optic disc.8 Based on kinetic perimetry, Lanshe and Rucker reported progressive visual field loss in 43% of patients (6 of 14 patients) over a period of 6 months to 24 years.9 Lee and Zimmerman also used kinetic perimetry and observed that the rate of visual field loss for optic nerve head drusen over a 36-month interval of time was 1.6% per year.10
In our case and during the follow-up period, which at 25 years is the longest we are aware of, we discovered progressive deterioration of visual fields in both eyes that was exclusively based on kinetic perimetry initially and on automated perimetry later on because OCT was not helpful due to the peripapillary location of the optic nerve head drusen.
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- Mustonen E. Pseudopapilloedema with and without verified optic disc drusen: a clinical analysis: II. Visual fields. Acta Ophthalmol (Copenh). 1983;61:1057–1066. doi:10.1111/j.1755-3768.1983.tb01493.x [CrossRef]
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- Greenfield DS, Bagga H, Knighton RW. Macular thickness changes in glaucomatous optic neuropathy detected using optical coherence tomography. Arch Ophthalmol. 2003;121:41–46.
- Katz BJ, Pomeranz HD. Visual field defects and retinal nerve fiber layer defects in eyes with buried optic nerve drusen. Am J Ophthalmol. 2006;141:248–253. doi:10.1016/j.ajo.2005.09.029 [CrossRef]
- Lanshe RK, Rucker CW. Progression of defects in visual fields produced by hyaline bodies in optic disk. Arch Ophthalmol. 1957;58:115–121.
- Lee AG, Zimmerman MB. The rate of visual field loss in optic nerve head drusen. Am J Ophthalmol. 2005;139:1062–1066. doi:10.1016/j.ajo.2005.01.020 [CrossRef]