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Lawrence M Strenk, Susan A Strenk, Bosco S Tjan, Kenneth L Lu, Suquin Guo, Liliana Werner; MRI Measurement of Choroidal Stretching Alleviated by Cataract Surgery. Invest. Ophthalmol. Vis. Sci. 2014;55(13):748.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the effect of cataract surgery on the choroid.
MRI is not impeded by the iris or optical distortions and has the unique ability to visualize the entire crystalline lens or artificial intraocular lens (IOL) and its relationship to the entire choroidal perimeter. MRI images were collected from both eyes of subjects who had monocular IOL implantation or, in one case, the same eye before and after cataract surgery (N = 8, ages 61-76). Images were collected using either a 1.5T (General Electric) or a 3T (Siemens) imager, custom RF eye imaging coils (MRI Research), and T1 contrast weighting. The choroid appears hyperintense to surrounding tissue in the resulting images and its circumferential perimeter was measured in axial slices.
The choroidal perimeter is shorter after cataract surgery, the mean difference being 1.120 ± 0.22 mm (mean ± SE) P = 0.0016. A linear regression of Δchoroidal length vs. age was not statistically significant, but did show a trend toward increasing with age P = 0.147 for these 8 subjects. The ciliary muscle apex moved posteriorly by 0.54 ± 0.10 mm P = 0.0011 after cataract surgery.
We have previously reported that life-long crystalline lens growth displaces the uvea anteriorly and that cataract surgery returns the uvea, most notably the ciliary muscle, to a relatively youthful antero-posterior position. Similarly, this study reveals that the choriodal length is shorter in eyes that have undergone cataract surgery, suggesting that the age-enlarged crystalline lens stretches the choroid, possibly thinning both the choroid and retinal nerve fiber layer. Cataract surgery, in many cases, lowers intraocular pressure (IOP), probably by directly opening the angle. Cataract surgery also appears to alleviate choroidal stretching and associated mechanical stresses. This may affect the disease trajectory of glaucoma as well as other blinding retinal diseases, such as wet and dry age related macular degeneration, and diabetic retinopathy as well as retinal tears and both retinal and vitreous detachment. These effects may wear off with abundant Soemmering’s ring that may again displace the uvea anteriorly.
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