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Nathan Farley, Aman Shukairy, Brandon DeCaluwe, Bret Hughes, Saya Nagori, Mark S Juzych, Anju Goyal, Chaesik Kim; The Effect of Cataract and Cataract Extraction on Cirrus OCT Measurements in Glaucoma and Glaucoma Suspect Patients. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4761.
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To assess the effect of the presence of cataracts and cataract extraction on signal strength (SS) and retinal nerve fiber layer (RNFL) thickness using Cirrus optical coherence tomography (OCT) in patients diagnosed with glaucoma or glaucoma suspect.
A retrospective chart review of 167 patients diagnosed as glaucoma or glaucoma suspect at Kresge Eye Institute in Detroit, MI who underwent cataract extraction and had received pre and post-operative Cirrus OCT testing was performed. Pre and post-operative SS and RNFL thickness measurements were collected and the differences analyzed by paired t-tests.
A total of 167 patients, 49 men and 118 women, mean age of 71.6 years, were included in the study. Forty-eight (28.7%) of the patients also received an adjunctive glaucoma intervention (iStent, trabeculectomy, Ex-Press Shunt) at the time of their cataract extraction. The mean pre-op SS was 6.9 vs. mean post-op SS of 7.9, a mean increase of 1.0 (p <0.0001). Patients undergoing cataract extraction alone had a mean increase in SS of 1.2 (p <0.0001), vs. 0.5 in patients undergoing cataract extraction plus glaucoma intervention (p = 0.0448). The type of cataract (cortical vs nuclear sclerotic vs posterior subcapsular) was not found to significantly affect signal strength measurements. The mean pre-op RNFL thickness measurement was 75.4 microns vs. a mean of 80.8 microns postoperatively, a difference of 5.4 (p <0.0001). Cataract extraction only patients had a mean increase in RNFL thickness of 4.4 microns (p = 0.001) postoperatively, vs 7.1 microns in cataract plus glaucoma intervention patients (p = 0.0007).
Our data suggests that the presence of cataract and cataract extraction significantly affects SS and RNFL thickness measurements using Cirrus OCT. In our study, we found a significant increase from pre to post-cataract extraction measurements of SS and mean RNFL thickness in patients with a diagnosis of glaucoma or glaucoma suspect. As cataract and glaucoma are two of the most prevalent ophthalmologic conditions in our aging population, it is important to understand the effect that cataract formation may have when evaluating for glaucoma with Cirrus OCT.
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