Swept-source optical coherence tomography findings in peripheral drusen.

A 50-year-old otherwise healthy female was examined during her routine checkup. The unaided visual acuity was 20/20 OU. Anterior segment examination of OU including intraocular pressure was unremarkable. Funduscopic examination of OU (Optos Inc.) revealed small multiple, discrete, yellow spots in the peripheral fundus more so in the nasal area [Fig. 1a and b]. On ultra wide field autofluorescence imaging, these lesions appeared mostly as hyperautofluorescent with few being hypoautofluorescent [Fig. 1c and d]. The patient was diagnosed to have peripheral drusen. The posteriorly located drusen [Fig. 2a, seen as blue circle in Fig. 1b] were examined with swept-source optical coherence tomography (SS-OCT, Topcon Inc.). On SS-OCT, these lesions extended well into the inner retinal layers [Fig. 2b, blue arrows], even causing the localized elevations of retina. These lesions were covered by retinal pigment epithelium (RPE) and were sandwiched between the RPE and Bruch's membrane, thereby confirming the diagnosis of drusen. The SS-OCT findings were similar in hyper- and hypo-autofluorescent drusen. The patient was advised regular follow-up.

Figure 1

Ultra wide field pseudocolor photographs of the right and the left eyes (a and b) of patient showing peripheral drusen. The blue circle in Fig. 1b reflects the area examined with swept-source optical coherence tomography. Ultra wide field autofluorescence of the right and the left eye (c and d) showing peripheral drusen as hyperautofluorescent with few being hypoautofluorescent due to retinal pigment atrophy

Figure 2

The color photograph (a) of area examined with swept-source optical coherence tomography. The green arrow in Fig. 2a shows location and direction of swept-source optical coherence tomography scan. Swept-source optical coherence tomography scan (b) of drusen shows lesions covered with retinal pigment epithelium extending up to the inner retinal layers causing localized elevations of retina. The choroidal thickness decreases toward the periphery

Discussion

The drusen outside the major vascular arcades and those nasal to the optic disc are categorized as peripheral drusen.[1] Peripheral drusen are more common among age-related macular degeneration (ARMD) patients with affected family members than in isolated cases of ARMD, thereby indicating that they are a part of morphologic and genetic spectrum of ARMD.[12] Peripheral drusen have also been associated with peripheral exudative hemorrhagic chorioretinopathy,[3] a condition considered to be a peripheral form of neovascular ARMD or polypoidal choroidal vasculopathy.[4] As opposed to macular drusen, the peripheral drusen in this case were “giant” and were seen extending up to the inner retinal layers on SS-OCT. The exact pathophysiology and relevance of these lesions, however, are not clear.

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Conflicts of interest

There are no conflicts of interest.