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Shlomit F. Sandler, Alan G. Fong, Anurag Shrivastava; Pre- And Post-dilation Iolmaster Biometric Measurements In Preoperative Cataract Assessment. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6228.
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To determine the relationship between biometric data collected by the IOLMaster® (Zeiss Humphrey Systems, V 5.4) in phakic eyes before and after dilation.
Phakic eyes were evaluated using the IOLMaster. Biometric measurements, including axial length, anterior chamber depth (ACD), corneal keratometry and anticipated refractive error for Alcon SN60WF and SA60AT intraocular lenses using the SRK II formula were recorded and compared for each eye before and after pharmacologic dilation.
98 eyes of 50 patients were enrolled (mean age 65.9 ± 9.8(SD) years). No statistically significant difference was found between the axial lengths (mean difference -0.012 ± 0.12 (mm), p=0.34, paired t-Test), corneal keratometry values (K1: mean difference -0.0079 ± 0.53 (D), p=0.88 and K2: mean difference 0.030 ± 0.42 (D), p=0.47) or expected post-surgical refractive error for the Alcon SN60WF (mean difference -0.0035 ± 0.34 D, p=0.92) or SA60AT (mean difference -0.0018 ± 0.34 D, p=0.96) IOLs before and after dilation. As expected, only anterior chamber depth (distance from the internal corneal surface to the anterior lens surface) demonstrated a statistically significant difference between undilated and dilated eyes (mean difference 0.16 ± 0.15 (mm), p<0.0001).
Biometric measurements obtained by the IOLMaster in pre-surgical evaluation for cataract extraction, including axial length, keratometry data, and expected post-surgical refractive error for a given IOL, demonstrate no statistically significant difference in undilated versus dilated phakic eyes. Anterior chamber depth, which relies on the pupillary margin in its measurement, is, as expected, affected by dilation. These findings may have implications in pre-surgical evaluations of cataracts, and prevent an additional office or clinic visit for biometric measurements in an already dilated patient.
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