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E. Lee, M. Kim, W. Wee, J. Lee; Accuracy of Intraocular Lens Power Calculation After Refractive Surgery in High Myope. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3139.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the reliability of historical method and the method using orbscan II topographic data to calculate intraocular lens (IOL) power after corneal refractive surgery in high myope who showed post-operative myopic regression after 3 years.
7 eyes of 4 patients who revealed nucleosclerosis which required cataract operation were retrospectively reviewed. The expected postoperative keratometric power was measured using refractive error by manifest refraction(MR), cycloplegic refraction(CR), and the surgically designed refractive amount. IOL power was calculated with SRK/T formula. To know that myopic regression is involved in the corneal regression or refractive lens change, calculations using post operative 6 months data and data of final visit were compared. Mean expected postoperative keratometric power was obtained by various data with refraction-derived keratometry method (A:post operative Manifest refraction(MR) at 6 months -preoperative MR, B: post regression MR-preoperative MR, C:postoperative MR at six months-preoperative cycloplegic refraction(CR), D:postregression MR -preoperative CR E:surgical refractive amount) or by the ORB scan optical power map method(F:The mean corneal power of the optical 4.0 mm zone, G:mean corneal power of 5.5 mm zone of the decentered area in decenterd corneal axis) The mean error in each IOL power prediction and the correlation with the real refraction after cataract operation was evaluated.
Mean spherical equivalent (SEQ) was -11.14 ± 3.68 D before refractive surgery. Mean SEQ at six months and at the time of regression was -1.33 ± 0.9 D, and -4.4 ± 2.21 D, respectively. Mean manifest refractive error was -1.90 ± 1.64 D after 1 month of cataract surgery. The correlation between the calculated power of each method and the real power was significantly higher in the clinical history method using the ΔSEQ value of C(postoperative MR - preoperative CR) and the surgical refractive amount(E). The presence of myopic regression showed no statistical significance in IOL power calculation.
In the high myope who had undergone refractive surgery , the clinical history method using the ΔSEQ value of (postoperative MR - preoperative CR), or the surgical refractive amount showed statistically significant prediction than method using optical power map, regardless of the presence of myopic regression.
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