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OCT imaging of retina useful in detecting glaucoma ‘masqueraders’
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Optic nerve and macular optical coherence tomography can be helpful in distinguishing between glaucoma and glaucoma masqueraders, according to researchers.
Researchers reported a case series of 4 patients and their spectral-domain OCT findings with retinal disease or nonglaucomatous optic neuropathy, who presented with suspected or previously diagnosed normal-tension glaucoma.
The first patient was found to have marked diffuse retinal nerve fiber layer (RNFL) and macular thinning on OCT due to cancer-associated retinopathy, researchers wrote. The 76-year-old woman was referred after cataract surgery failed to relieve her symptoms of progressive vision loss.
The second patient showed deep focal inferotemporal RNFL loss with a corresponding arc of macular thinning on OCT, according to the researchers. The 60-year-old woman complained of left peripheral vision loss with a history of left carotid aneurysm that was coiled. Her IOP was 18 mm Hg in the right eye and 17 mm Hg in the left eye with central corneal thickness of 497 in her right eye and 502 in her left eye.
OCT in the third patient revealed global RNFL and macular thinning from optic nerve hypoplasia, researchers said. He was referred for a second opinion of advanced normal-tension glaucoma in the left eye. The medical history of the 43-year-old male was significant for unexplained seizures with normal brain magnetic resonance imaging, sleep apnea and hypertension. Further, ophthalmic history was significant for blindness in the right eye since birth and maximum IOPs of 16 mm Hg in the right eye and 19 mm Hg in the left.
The fourth patient had bilateral, symmetric superior and temporal RNFL thinning on OCT with corresponding inferior arcuate defects, consistent with superior segmental optic nerve hypoplasia, they said. The 18-year-old woman was diagnosed and treated for glaucoma for 7 years before transferring care. She had a history of exotropia surgery in the left eye and moderate to high myopia in both eyes.
Researchers reported that there can be overlap in the optic nerve and retinal imaging findings with other diseases.
“In the first case, diffuse RNFL thinning by OCT was an artifact caused by loss of normal architecture from CAR,” researchers added. “The preservation of central macular thickness with severe thinning of the peripheral retina and apparent severe loss of RNFL thickness in the absence of a total cup indicated the possibility of nonglaucomatous etiology,” they continued. They found that a review of the individual cross-sectional images of the macula, revealed the loss of rod photoreceptors.
These nonglaucomatous “diagnostic dilemmas” can be mistaken for glaucomatous optic neuropathy, especially with visual field defects and normal IOP, the researchers stated. Researchers recommend OCT imaging of both RNFL and the macular region in aiding the detection of “glaucoma masqueraders.” –by Abigail Sutton
Disclosure: Kuo was supported by a fellowship from The Society of Heed Fellows. Asrani received lecture honoraria from Heidelberg Engineering.
Perspective
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Derek MacDonald, OD, FAAO
In some cases, the diagnosis of glaucoma is relatively straightforward. Normal-tension glaucoma, however, is a challenging differential diagnosis that demonstrates the complementary roles of ancillary structural and functional analyses, detailed case history and careful clinical assessment.
Kuo and Asrani’s review of glaucoma masqueraders highlights important red flags that suggest nonglaucomatous etiologies, including:
—a history of ocular trauma or surgery, or acute systemic hypotension;
—an acute onset of symptoms, accompanying pain, or neurologic or cranial nerve involvement;
—patient age less than 50 years;
—best-corrected visual acuity less than 6/12;
—a relative afferent pupillary defect or color vision defect;
—neuroretinal rim pallor: nonglaucomatous neuropathies rarely show significant cupping, but often show early swelling and late pallor;
—a visual field defect respecting the vertical midline or not commensurate with optic nerve head status;
—extreme retinal nerve fiber layer (RNFL) thinning involving the papillomacular bundle in the absence of extreme cupping; and
—OCT abnormalities involving the outer retina rather than the RNFL/ganglion cell-inner plexiform layer.
Normal-tension glaucoma is an excellent reminder that ancillary tests inform, but do not make our clinical decisions: “… any result on standard automated perimetry or spectral domain OCT … needs to be interpreted along with the total clinical picture …” (Rao et al, 2015).
Reference:
Rao HL, et al. J Glaucoma. 2015 Jun-Jul;24(5):e69-74. doi: 10.1097/IJG.0000000000000048.
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