A 51-year-old woman was examined 8 years after surgical removal of a nonfunctional pituitary adenoma discovered because of sudden onset headache and visual loss. At that time, she underwent craniotomy for subtotal tumor resection. After surgery, left homonymous visual field loss was detected and remained stable.
On examination, visual acuity was 20/20 in both eyes with a left relative afferent pupillary defect. Automated perimetry demonstrated complete left homonymous hemianopia (Fig. 1A). On ophthalmoscopy, there was temporal right optic disc pallor and band optic atrophy in the left eye (Fig. 1B). With infrared laser photography, there were semilunar hyporeflective areas temporal to the right macula and in the left nasal macular area up to the temporal side of the optic disc (Fig. 2A). Spectral domain optic coherence tomography (OCT) showed thinning of both the retinal nerve fiber layer (RNFL) and the retinal ganglion cell (RGC) layer in the right temporal and left nasal hemiretinas (Fig. 2B). High-resolution horizontal OCT through the macula showed thickening of the inner nuclear layer (INL) in the right hemiretina of both eyes and several points of microcystic edema matching the hyporeflective images on infrared photography (Fig. 3).
Funduscopic abnormalities in patients with anterior visual pathway disease have been limited to optic disc edema or pallor and peripapillary RNFL atrophy. Advances in OCT technology have allowed segmentation of retinal layers and documentation of both RNFL and RGC layer loss in the macular areas of patients with optic atrophy (1–3). Secondary thickening and microcystic retinal edema (MRE) in the INL often are seen in such eyes (1–3). MRE in the INL initially was described in patients with multiple sclerosis (MS) and thought to represent direct involvement of the retina (3,4). Reports were subsequently published of MRE in patients with other optic nerve, chiasmal, and optic tract lesions, showing that the finding is not specific for MS (2,5–9). Although the exact mechanism for development of microcysts in the INL is still uncertain, MRE now is considered a secondary result of retrograde retinal degeneration (2,3,8). This is supported by experimental histopathologic studies after optic nerve injury (10,11).
Multicolor laser imaging of the retina is based on differences in the reflectance of blue, green, and infrared light (12). Infrared laser allows visualization of deeper retinal layers, especially the outer neural retina and retinal pigment epithelium. Hyporeflectant images have been described in a number of eyes with optic atrophy from various causes (8,13).
Our report illustrates the correspondence between hyporeflectant images detected with multicolor laser imaging and RGC and RNFL thinning and INL thickening. The correspondence is greatest with INL thickening due to the presence of retinal microcysts (Figs. 2, 3). Further studies are needed to evaluate the frequency of these findings and shed light on the pathogenic mechanisms involved. Nevertheless, infrared photography can provide useful information in patients with anterior visual pathway disease and facilitate the diagnosis of an optic tract lesion.
STATEMENT OF AUTHORSHIP
Category 1: a. Conception and design: R. B. Araujo, A. C. F. Suzuki, and M. L. R. Monteiro; b. Acquisition of data: R. B. Araujo, A. C. F. Suzuki, and M. L. R. Monteiro; c. Analysis and interpretation of data: M. L. R. Monteiro, R. B. Araújo, L. P. Cunha, and R. C. Preti. Category 2: a. Drafting the manuscript: M. L. R. Monteiro, R. B. Araújo, and A. C. F. Suzuki; b. Revising it for intellectual content: M. L. R. Monteiro, R. B. Araújo, A. C. F. Suzuki, L. P. Cunha, and R. C. Preti. Category 3: a. Final approval of the completed manuscript: M. L. R. Monteiro, R. B. Araújo, A. C. F. Suzuki, L. P. Cunha, and R. C. Preti.
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