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OCT-GCC more sensitive at detecting chiasmal compression
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The use of OCT-ganglion cell complex analysis may be a more effective way to detect compressive chiasmopathy or optic neuropathy early on, according to findings published in the journal, Pituitary.
Richard J. Blanch, BSc, MBChB, PhD, and colleagues identified patients with sellar tumors and chiasmal compression with normal visual fields who had retinal nerve fiber layer (RNFL) damage using ganglion cell complex (GCC) on OCT.
“The role of OCT in the diagnosis of compressive chiasmopathy is less emphasized in the [Congress of Neurological Surgeons] guidelines,” Blanch, an ophthalmologist at Emory University, the University of Birmingham and Royal Centre for Defence Medicine, and colleagues wrote. “However, recent publications have reported abnormal GCC analyses in patients with radiographic chiasmal compression but normal visual fields and normal RNFL thickness, suggesting that the GCC analysis may be more sensitive to detect compressive damage.”
The researchers wrote that the data from seven patients found OCT-GCC thickness detected compressive chiasmopathy before visual defect became apparent on standard automated visual field testing.
They said that without OCT, the patients would have been labeled as having normal visual function and no evidence of compressive chiasmopathy. With only OCT-RNFL analysis, three of the patients would still have been diagnosed as having no compression of the anterior visual pathways.
“With this report of a small series of patients, we hope to show neurosurgeons that OCT-GCC analysis can (be) more sensitive and reliable than visual field testing with standard automated perimetry or OCT-RNFL analysis in the detection of chronic compressive chiasmopathy and should be routinely used in addition to automated perimetry as part of the pretreatment ophthalmologic evaluation of patients with sellar masses,” the researchers wrote. – by Earl Holland Jr.
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Jarett A. Mazzarella, OD, FAAO
The study by Blanch and colleagues found that OCT-GCC is more sensitive than standard automated perimetry in the detection of compressive lesions of the optic chiasm. This finding has great clinical significance because of the morbidity and mortality that is associated with suprasellar tumors. The rapid and objective nature of performing OCT scans enables clinicians to quickly screen for these lesions in patients with headache or other symptoms that may signal the presence of a suprasellar mass. This is especially valuable in patients that have difficulty performing reliable visual field examinations.
OCT has limitations. OCT compares measurements to a limited normative data base, which can lead to erroneous results. OCT is unable to differentiate between compromised retinal ganglion cells and artifacts or poor scan quality. When in doubt, neuroimaging is indicated to definitively diagnose chiasmal compression.
In current practice, a combination of neuroimaging, clinical examination and ancillary testing including automated perimetry, OCT-RNFL and OCT-GCC may best evaluate visual compromise in patients with compressive chiasmal lesions.
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