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Biometric Accuracy in High Hypermetropes and Myopes. Mangat S, Kumar B V, Prasad S Arrowe Park Hospital, Wirral University Hospital NHS Trust No financial interests. Introduction. Cataract surgery in patients with myopia and hypermetropia can be technically challenging .
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Biometric Accuracy in High Hypermetropes and Myopes Mangat S, Kumar B V, Prasad S Arrowe Park Hospital, Wirral University Hospital NHS Trust No financial interests
Introduction • Cataract surgery in patients with myopia and hypermetropia can be technically challenging . • These challenges arise due to extremes of axial length which can lead to complications during biometry. • This can lead to potential intra and postoperative complications particularly with postoperative surprises particularly anisometropia. • Hence obtaining accurate biometry in these patients is essential to ensure that the cataract surgery is successful.
Methods • Retrospective review of medisoft database was undertaken of cataract surgery carried out between Jan 2005 - September 2009 • Surgery was carried out by Consultants, Fellow and Registrars. • Myopia is defined when patient has an axial length more than 26mm • Hypermetropia is defined when patient has an axial length less than 22mm • Preoperative refraction, biometry measurements , visual acuity pre and post cataract surgery were all documented. • Deviation from - predicted postoperative outcome and - final best corrected visual acuity were recorded
Conclusions • Postoperative refraction in the <22mm and >26mm groups was within +/-1D in 84% and 86 % respectively • There was no statistically significant difference between the mean post operative spherical equivalent -0.01 (<22mm) and 0.70 (>26mm). Paired Student t Test >0.05 • There was no statistically significant difference between the mean deviation from predicted refraction -0.01 (<22mm) and -0.09 (>26mm). Paired student t Test >0.05
Conclusions • 89.5% cases with Axial Lengths 22-26mm had a postoperative refraction of +/- 1D • Some postoperative surprises were noted as a result of Biometry errors which was rectified later with further surgery. • It may be wise to discuss this finding preoperatively when dealing with patients with extremes of axial length
Available Evidence • Zuberbuhler et al state that 53.2% of patients were +/- 1D of predicted in those with axial lengths above 30mm • Lyle et al studied 106 highly myopic eyes. Postoperative corrected visual acuity was 20/40 or better in 94% of eyes, and uncorrected visual acuity was 20/40 or better in 77% of eyes at 27 months in those with axial lengths >26mm • Maclaren et al state 55% patients were +/- 1D of predcited in 76 eyes requiring IOLs between 30-35D
References • 1. Zuberbuhler B, Seyedian M, Tuft S. Phacoemulsification in eyes with extreme axial myopia. J Cataract Refract Surg. 2009 Feb;35(2):335-40. • 2. Lyle et al. Phacoemulsification with intraocular lens implantation in high myopia. J Cataract Refract Surg. 1996 Mar;22(2):238-42. • 3. MacLaren RE et al. Biometry and formula accuracy with intraocular lenses used for cataract surgery in extreme hyperopia. Am J Ophthalmol. 2007 Jun;143(6):920-931.