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B. Azizi, S. Singer, T. Wong, C. Hudson; Assessment of Retinal Arteriolar Hemodynamics in Patients With Cataract. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2800.
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To determine the impact of cataract on the quantitative, noninvasive assessment of retinal arteriolar hemodynamics using the Canon Laser Blood Flowmeter (CLBF).
Six patients scheduled for extracapsular cataract extraction (ECCE) using phacoemulsification and intraocular lens implantation were randomly selected. Patients were aged between 61-84 years (Mean 71, SD 8.5), had no corneal abnormalities and no post-operative complications. Each subject underwent the assessment of intra-ocular light scatter status using ETDRS visual acuity charts (10% & 90% contrast) and the Brightness Acuity Tester before and after the surgery. The severity of cataract was also documented using the Lens Opacity Classification System (LOCS) III. Retinal arteriolar hemodynamics were then acquired at the same point on the superior temporal arteriole before and after the surgery using the CLBF. The post-operative measurements were done at least 6 weeks after the surgery to allow for full recovery.
Group mean arteriolar diameter was significantly reduced post-operatively (paired t-test, p=0.046) from 115.4 µm to 103.8 µm; however, centreline blood velocity was unaffected (paired t-test, p=0.162), while retinal blood flow showed a non-significant trend to decrease post-operatively (p=0.057) from 13.0 µl/min to 9.3 µl/min.
The apparent change in arteriolar diameter between pre- and post-operative values, in the abscense of any changes in the centerline blood velocity, can be explained as an artifact of the cataract. The vessel densitometry technique used to quantify vessel diameter is sensitive to the light scatter induced by cataract and measures erronously increased values in the presence of lenticular opacity. Caution has to be exercised in the interpretation of quantitative retinal hemodynamic measurements in situations with existing cataract.
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