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P.A. Good, R. Siddiqi; Comparison between 20 Mega Hertz Ultrasound and Ocular Coherence Tomography (OCT) in macular holes and cystoid macular oedema. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2366.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Ocular Coherence Tomography (OCT) provides high resolution images of the macula which readily identifies the presence of macular holes and sub retinal cysts. However, as this technique relies on light enrgy it cannot be performed in the presence of opaque media. Recent advances in B Scan ocular echography (USG) have resulted in the development of the 20 MHz probe which gives high resolution images of the posterior as well as anterior segment. This study compares the OCT with 20 MHz USG imaging of the macula in order to evaluate its use in macular holes/oedema. Methods: Fifteen patients (23 eyes) with macular hole (3 grade 1a, 6 grade 2, 8 grade 3 and 6 grade 4), and 15 patients (21 eyes) with cystoid macular oedema (CMO) underwent OCT3 macular analysis and USG imaging of the posterior pole using a Quanteltm Cine Scan B scanner with a 20 MHz probe. The OCT and USG images were assessed by two independent observers who were unaware of the diagnosis. The presence of macular holes was noted and these were graded from 1 to 4. Any evidence of CMO was noted as were the presence of epiretinal membranes or the presence or absence of a PVD. Results: The OCT identified the macular holes in all 23 eyes, and correctly graded 20 of them. The OCT also identified all 21 eyes with CMO. The 20 MHz USG identified and correctly graded 19/23 eyes (83%) with macular hole, but failed to identify 2 eyes with grade 1a, and 2 eyes with grade 2 holes. The USG identified an epiretinal membrane in 6 eyes with CMO, but the OCT identified only 4 of these. The USG identified a PVD in all 6 eyes with grade 4 hole, but the OCT identified only 3 of these. Conclusions: The OCT provides excellent high–resolution images of the macula enabling accurate diagnosis of macular holes and CMO. However, OCT requires clear media and good patient compliance. The 20 MHz B Scan USG provides a good alternative when OCT cannot be performed , and can give useful additional information as to the presence of epiretinal membrane or PVD.
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