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Abstract #46149 Published in IGR 13-2
Comparison of the influence of cataract and pupil size on retinal nerve fibre layer thickness measurements with time-domain and spectral-domain optical coherence tomography
Cheng CS; Natividad MG; Earnest A; Yong V; Lim BA; Wong HT; Yip LWClinical and Experimental Ophthalmology 2011; 39: 215-221
Background: To investigate and compare the effect of cataract and pupil size on retinal nerve fibre layer (RNFL) thickness measurements using spectral-domain optical coherence tomography (Cirrus OCT) and time-domain OCT (Stratus OCT). Design: Prospective, hospital-based study. Participants: Twenty-five eyes from 25 normal subjects undergoing cataract surgery. Methods: Three retinal nerve fibre layer (RNFL) thickness measurements were taken before and after dilation, preoperatively and postoperatively, using Cirrus 200null200 Optic Disc Scan and Stratus Fast RNFL Scan. Main Outcome Measures: Linear regression, intraclass correlation coefficient (ICC) and coefficient of variation analysis. Results: Cataract removal caused significant increase in RNFL measurements in both modalities (Cirrus P<0.02; Stratus P<0.001). There was no significant difference in the increase in measurements between the two machines. Pupil dilation had variable and non-statistically significant effect in both (P>0.05). ICC showed excellent reproducibility with Cirrus OCT after mydriasis, preoperatively (ICC=0.78-0.90) and postoperatively (ICC=0.90-0.97), but poor reproducibility before mydriasis (P<0.75). Stratus OCT achieved excellent reproducibility after cataract removal both before (ICC=0.86-0.96) and after mydriasis (ICC=0.92-0.95), but poor reproducibility before cataract surgery (P<0.75). Conclusions: Cataracts, not pupil size, cause significant underestimation of RNFL measurements in both Cirrus and Stratus OCT. The extent of influence exerted does not appear different between the two instruments. Reproducibility of each machine appears to be affected differently. Mydriasis is required to achieve excellent reproducibility with Cirrus OCT, and media clarity is required with Stratus OCT.
L.W. Yip. Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore. Email: leonard-yip@ttsh.com.sg
Classification:
6.9.2.2 Posterior (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis > 6.9.2 Optical coherence tomography)
2.9 Ciliary body (Part of: 2 Anatomical structures in glaucoma)
9.4.4.5 Other (Part of: 9 Clinical forms of glaucomas > 9.4 Glaucomas associated with other ocular and systemic disorders > 9.4.4 Glaucomas associated with disorders of the lens)