| Objective: To study the change in anterior chamber diameter, anterior chamberdepth (ACD), the optical aberrations of the cornea after phacoemlsification andfoldable intraocular lens (IOL) implantation with Pentacam. To compare anteriorchamber diameter and ACD measurements using Pentacam and panoramic ultrasoundbiomicroscopy (UBM) and the aberrations of the anterior surface of cornea measuredwith Pentacam and iTrace wavefront aberrometer.To study the implementation of anterior chamber diameter forecasting systembased on artificial nueral network.Methods: Seventy-nine eyes of 60 patients with age-related cataract which wereperformed small-incision phacoemulsification and foldable IOL implantation wereinvolved in this study. The anterior chamber diameter in horizontal meridian andACD were measured by Pentacam before surgery, and 1 week, 1 months, 2 monthsafter surgery. The anterior chamber diameter in horizontal and vertical meridian andACD were measured by panoramic UBM before and 2 months after surgery. All eyeswere measured with Pentacam and iTrace wavefront aberrometer two months aftercataract surgery at random order. We record Zernike coefficients, RMS of total highorder aberration (HOA), spherical, coma and trefoil aberration, from 2 order to 6order aberrations.One hundreds and twenty-one eyes of 99 patients with age-related cataractwhich were performed small-incision phacoemulsification and foldable IOLimplantation and 176 eyes of 88 normal youth persons are selected. The anteriorchamber diameter in horizontal meridian, anterior chamber depth (ACD), cornealcurvature, radius of corneal curvature, axial length are measured by panoramic UBM,A-ultrasonoscope, corneal topographer and corneal keratometer. Based onback-propagation (BP) neural network, we used a forecasting method to forecast thediameter of anterior chamber. 38 eyes of 38 patients and 22 eyes of 14 normal youthpersons were selected to evaluate the validity and acuity.Results: In all patients, the horizontal anterior chamber diameter was widenedsignificantly after surgery (F=7.170, P=0.009), and the ACD was deepened (F= 26.439,P＜0.05). There were no statistically significant difference among thehorizontal anterior chamber diameters and the ACD 1 week, 1 months, 2 months aftersurgery (P＞0.05). There were no statistically significant difference between Pentacamand UBM in the horizontal anterior chamber diameters before and 2 months aftersurgery (t=0.231, P=0.818; t=1.017, P=0.311). In the ACD before surgery, thedifference between the two devices was not statistically significant (t=0.153,P=0.995), but after surgery the difference was statistically significant (P＜0.05). In theRMS of the total HOA, spherical aberration, coma, trefoil and from 2 order to 6 orderaberrations of the anterior surface increased slightly from a mean of (1.025±0.213)μm preoperatively to (1.050±0.280)μm postoperatively (t= 0.717, P＞0.05). The RMSof total HOA, spherical aberration and from 2 order to 6 order aberrations showedstatistically difference between Pentacam and iTrace (P＜0.05).In all patients, There was a significant positive correlation between thepreoperative and postoperative anterior chamber diameters (r=0.805,P＜0.05). Theregression equation was y=5.326+0.556x. Using Matlab-BP ANN software, thediameter of anterior chamber can be forecasted. The differences between the resultsof different methods were not statistically significant (P＞0.05).Conclusion: After phacoemulsification and foldable IOL implantation,Pentacam revealed that the anterior chamber diameter was widened and the ACD wasdeepened. After one week, the anterior chamber diameter and ACD remainedunchanged. Pentacam and UBM can both be used for the anterior chamber diametermeasurements and yielded comparable results. But for the ACD, the difference wassignificantly lower when the ACD was measured with the Pentacam after surgery.Phacoemulsification cataract surgery does not systematically degrade the opticalquality of the anterior corneal surface. There were partly difference of Zernikecoefficients obtained by Pentacam and iTrace.Using Matlab-BP ANN software, the diameter of anterior chamber can bepredicted by input parameters of anterior chamber depth, corneal curvature or radiusof corneal curvature and axial length.
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