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Michel R. Rubin, Usha S. Rao, Shan C. Lin, Travis Porco, Robert L. Stamper; Corneal Biomechanical Properties: a Comparison between Phakic and Pseudophakic Eyes in Glaucoma Patients. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2804.
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© ARVO (1962-2015); The Authors (2016-present)
Investigate the association between corneal biomechanical parameters and phacoemulsification with intraocular lens implantation in glaucoma patients using the Ocular Response Analyzer (ORA).
One hundred and thirty one eyes of 85 glaucoma patients were divided into two groups: phakic (76) vs. pseudophakic (55) eyes. The patients underwent measurement of corneal hysteresis (CH), corneal resistance factor (CRF), and cornea-compensated intraocular pressure (IOPcc) via the ORA. One glaucoma specialist reviewed the clinical chart to determine the cup-to-disk ratio (CDR), intraocular pressure (IOP) by Goldmann applanation tonometry, central corneal thickness (CCT) by an ultrasonic pachymeter and glaucoma severity classification by Humphrey 24-2 visual field (HVF) analysis. Exclusion criteria were intraocular surgery other than cataract surgery, complications during cataract surgery, less than one year out from cataract surgery, and less than 6 months out from laser trabeculoplasty.
In both groups, a lower CH was associated with a higher IOP (p=0.007), a higher IOPcc (p=0.0001), a lower CCT (p=0.001), an older age (p=0.001) and more severe HVF defects, however this association did not reach statistical significance (p=0.08). The pseudophakic group was on overage older age than the phakic group (77.7±8.61 vs. 65.2±12.5 years, p<0.001). The statistical analysis was done controlling for this difference by linear mixed effects regression.The CRF (9.31±13.7 vs. 8.57±11.5, p=0.15), IOP (14.2±3.68 mmHg vs. 15.1±3.59 mmHg, p=0.19) and IOPcc (17.2±4.47 vs. 17.1±3.91mmHg, p=0.36) were similar between pseudophakic and phakic groups respectively. The CCT, CDR and severity of HVF classification were similar between both groups (p>0.05) as well. However, CH was significantly lower in the pseudophakic than in the phakic group (8.59±1.40 mmHg vs. 9.12 ± 1.59 mmHg, p=0.04).
Despite adjusting for age and having similar CCT, CDR, severity of HVF classification, CRF, IOP and IOPcc, the pseudophakic group had a lower CH compared to the phakic group (8.59±1.40 mmHg vs. 9.12±1.59 mmHg, p=0.04). These findings suggest an independent correlation that may be related to a change in corneal biomechanics after phacoemulsification and intraocular lens implantation in patients with glaucoma.
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