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M.M. Merchea, M. Lagana, I. Cox; Effects of Dilation and Dilation Reversal Agents on Pupil Center Decentration in Refractive Surgery Candidates . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4357.
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Purpose: To measure pupil center decentration over time after the instillation of mydriatic and miotic pharmaceutical agents. Methods: Thirty preoperative eyes (15 subjects) were enrolled in this prospective non–randomized study. All measurements were made using the Zywave II WaveFront Aberrometer (v.4.45sp3). Phase I (Dilation): Pupil center location and wavefront measurements were captured at baseline and in 5 minute intervals up to 30 minutes after instillation of 1 drop each of 2.5% phenylephrine and 1% tropicamide. Phase II (Dilation Reversal): Two drops of 0.5% dapiprazole hydrochloride (REV–EYES; Bausch & Lomb, NY) were instilled 30 minutes after completion of Phase I. An additional 2 drops were added 5 minutes later according to package insert dosage recommendations. Pupil center location and wavefront measurements were captured in 30 minute intervals from 90 to 180 minutes after instillation of REV–EYES. Results: Phase I: Mean pupil center decentration was statistically and clinically significant within the first 15 minutes after instillation of the mydriatic combination (ANOVA, p<0.001) in the vertical meridian. After the 15 minute time point, pupil center decentration in the vertical meridian stabilized at a magnitude of –150um. There was no statistically significant mean pupil center decentration in the horizontal meridian (ANOVA, p=0.169) in the dilation phase. A mean spherical refractive error shift of +0.45D (p=0.024) and mean Defocus (Z200) shift of –0.35um (p<0.027) were observed by 20 minutes after dilation. There were no statistically significant changes in mean higher order aberrations normalized to baseline (p>0.05), although significant variation in individual eyes were observed. Phase II: Mean pupil center decentration in the vertical meridian stabilized at a magnitude of about +125um (p<0.001), 3 hours after instillation of REV–EYES. There were no statistically significant changes in mean higher order aberrations normalized to baseline (p>0.05), although significant variation in individual eyes were observed. Conclusions: Significant variability of pupil center decentration was observed early in the dilation time course, as a result of asymmetric pupil mydriasis. The results suggest that wavefront measurements should be made at least 20 minutes after instillation of mydriatic agents, when the pupil center location is stabilized. Mydriatic reversal drops should not be used with the intent of performing same–day refractive surgery, as centration of the treatment will not coincide with the manifest pupil center location.
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