Comparison of Intraocular Lens Calculation Formulas Measured by Immersion-Type A-Scan Ultrasound and Partial Coherence Interferometry

PURPOSE: To report the accuracy of intraocular lens (IOL) formulas according to axial length, anterior chamber depth, and mean corneal curvature when performing biometry with an immersion type A-scan with mannual keratomery and an IOL Master®. METHODS: Retrospective medical chart reviews were carried out for 82 eyes of 65 patients who underwent cataract surgery performed by a single surgeon. Biometry was performed using IOL Master®, mannual keratometry, and immersion type A-scan ultrasound in sequence. Prediction diopter was obtained using Sanders-Retzlaff-Kraff/Theoretical (SRK-T) and Holladay 1 formulas calculated with the biometric value measured by mannual keratomery and A-scan, and using SRK-T and, Holladay 2 formulas with IOL Master®. The final refractive outcome was determined as manifested refraction at least 7 weeks after the surgery, and it was compared with the preoperative prediction dipoter (D) of the IOL formulas. RESULTS: Mean axial length and mean keratomtric measurements as determined by A-scan with mannual keratomery showed significant statistical differences from those of IOL Master®. However, there was no difference in postoperative mean absolute error between biometric measurements, or among formulas according to axial length, anterior chamber depth, or mean corneal curvature. However, the percentage of actual refraction within ±0.50 D of the intended refraction was dirrerent among the four formalas according to axial length, anterior chamber dept, mean corneal curvature. CONCLUSIONS: Biometry measurement using the immersion-type A-scan with mannual keratomery is as accurate as that using IOL Master® for predicting the postoperative refractive state of cataract surgery. However, it is suggested that the best IOL formula be chosen according to axial length, anterior chamber depth, and mean corneal curvature.

Measurement of anterior chamber depth with three methods in patients with primary acute angle-closure glaucoma / 国际眼科杂志(Guoji Yanke Zazhi)

?AIM:To investigate the measurement of central anterior chamber depth ( ACD ) in patients with acute primary angle - closure glaucoma ( APACG ) with A - scan ultrasound, Pentacam and ultrasonic biological microscope ( UBM) .?METHODS: Thirty-five patients (35 eyes) with APACG were selected, of whom central ACD were measured with A-scan ultrasound, Pentacam and UBM.?RESULTS: The measurement values of ACD with A-scan ultrasound, UBM and Pentacam were 1. 5633±0. 2089, 1. 5783 ± 0. 2067, 1. 6275 ± 0. 2296mm, which was equal variance tested by the homogeneity of variance, and was significant different by multiple comparision (F=4. 074, P=0. 026). The difference of ACD between the two groups of A-scan ultrasound and UBM, A-scan ultrasound and Pentacam, UBM and Pentacam were statistically significant ( P = 0. 032, 0. 023, 0. 012 ). Altman- Bland analysis showed that the three methods were not consistent with each other.?CONCLUSION: The ACD value of the APACG with the three methods is the largest using Pentacam, followed by UBM and A - scan ultrasound. In clinical the three methods with different advantages can complement each other, but cannot be replaced. In order to obtain more accurate results, we should combine the advantage and make comprehensive analysis.

Comparison of lOL Master contact and immersion A - scan ultrasound measurements of anterior chamber depth / 国际眼科杂志(Guoji Yanke Zazhi)

AlM:To compare the results of lOL Master, contact and immersion A-scan ultrasound measurements for anterior chamber depth ( ACD ) , and evaluate the difference and consistency.METHODS:Fifty-eight cases (98 eyes) with age-related cataract during July to October in 2013 did the A-scan ultrasound with contact and immersion measurements and lOL Master to get the results of ACD. Difference in measurements between methods was assessed using the variance analysisi. Consistency was assessed using Bland-Altman.RESULTS:The ACD measured by lOL Master was 2. 31~3. 90mm, the mean was 3. 03 ± 0. 38mm. The ACD measured by contact A- scan ultrasound was 1. 51 ~4. 06mm, the mean was 2. 88 ± 0. 56mm. The ACD measured by immersion A-scan ultrasound was 1. 99 ~4. 17mm, the mean was 3. 17±0. 38mm. The results of lOL Master and contact A - scan ultrasound had statistical differences (P=0. 022<0. 05). The results of lOL Master and immersion A - scan ultrasound had statistical differences (P=0. 031<0. 05). The results of contact A-scan ultrasound and immersion A-scan ultrasound had statistical differences (P=0. 000<0. 05). The consistency between three methods was poor. CONCLUSlON: The rank of ACD of patients with cataract is immersion A-scan ultrasound, lOL Master and contact A-scan ultrasound. The consistency is poor, and the three methods can’t be interchanged clinically.

Comparison and observation of A-scan ultrasound biometry measurements before and after cataract surgery / 医学研究生学报

Objective Cataract surgery is also considered as a type of refractive surgery , but there is few research on the change of preoperative and postoperative ocular biometry measurements .The aim of the study was to compare the A-scan ultrasound biom-etry measurements before and after phacoemulsification with intraocular lens implantation , followed by the analysis on its clinical signifi-cance . Methods Dynamic observation was conducted in 188 eyes of 155 cataract patients who received cataract operation from January 2011 to January 2013 in the department of ophthalmology in Nanjing Gernal Hospital .Measurements were made before surgery and 14 days after surgery by Ultrascan Digital 2000 contact ultraound A-scan (Alcon), including anterior chamber depth (ACD), vitreous cham-ber depth ( V) and axial length ( AL) .Simultaneously , a prospective comparison of measurements was made by A-scan ultrasound in sit-ting and decubitus position .Measurements were also conducted in preoperative and postoperative visual acuity and intraocular pressure of the patients. Results visual acuity and intraocular pressure: The difference between preoperative and postoperative visual acuity [(0.17 ±0.19) vs (0.61 ±0.27)] and intraocular pressure [(15.09 ±8.50) mmHg vs (12.99 ±4.44) mmHg] was of statistical sig-nificance ( P0.05).V:The difference between peroperative and postoperative Vs was of significant difference (P<0.05).No significant difference existed between Vs in sitting and decubitus position before the operation [(16.568 ±2.406) mm vs (16.524 ±5.544) mm,with intraocular lens implantation can get better operation result. In addition, different measuring positions have no influence on A-scan ultrasound measurements except the postoperative vitreous cavity depth .

Comparison of the biometric measuring outcomes between Lenstar and A-scan ultrasound biometry or keratometer in cataract patient / 中华实验眼科杂志

Background The accuracy of biometric measurement is critical for precise diagnoses and prognosis evaluation of ocular diseases.Objective The present study was to evaluate the differences of Lenstar with A-scan ultrasound biometry or keratometer in ocular bio-measurement.Methods Written informed consent was obtained from each subject before examination.Total 43 eyes of 40 age-related cataract patients were enrolled in this study.Axial length,corneal curvature (K1,K2,Km) and intraocular lens (IOL) power were measured with Lenstar,A-scan ultrasound biometry and keratometer,separately.The differences of measuring outcomes were compared between these two methods according to a paired samples t test,and the agreement analysis of measuring outcomes between Lenstar and A-scan ultrasound biometry or keratometer was performed by Blant-Altman plots.Results Thirty-five eyes finished the clinical bio-measurement.The axial length was (23.341 ± 1.208) mm and (23.268 ±1.157)mm based on Lenstar method and A-scan ultrasound biometry method,respectively,with a insignificant difference between them(t =0.260,P=0.796).No significant differences were found in the K1,K2 and Km values between Lenstar and keratometer methods (t =0.526,P =0.601 ; t =0.927,P =0.357 ; t =0.213,P =0.832).The IOL power was (20.371 ±2.827) D and (20.729 ± 2.672) D,respectively in Lenstar method and keratometer method,without statistically significant difference between them (t =0.543,P =0.589).Bland-Altamn agreement analysis showed that the dots of 11％ (4/35),0％ (0/100),9％(3/35),9％ (3/35),6％ (2/35) were out of 95％ confidence limit,and the absolute values of maximal difference value between Lenstar and A-scan ultrasound biometry or keratometer methods was 0.39 mm,1.31 D,1.30 D,0.77 D and 1.00 D in ocular axial length,K1,K2 and Km values and IOL power,respectively.Conclusions As a new bio-measuring method,Lenstar can offer multiple biometric parameters by single procedure.However,an inconsistent measuring outcome is seen between Lenstar and Ascan ultrasound biometry or keratometer.So whether Lenstar can replace A-scan ultrasound biometry or keratometer still need further large simple clinical trail.