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Effect of intracorneal ring segment implantation on corneal asphericity 被引量:3
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作者 Canan A.Utine Ziya Ayhan Ceren Durmaz Engin 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2018年第8期1303-1307,共5页
AIM: To evaluate the visual, refractive and corneal asphericity changes after intrastromal corneal ring segment(ICRS) implantation for visual rehabilitation of keratoconus.METHODS: A total of 42 eyes of 32 patient... AIM: To evaluate the visual, refractive and corneal asphericity changes after intrastromal corneal ring segment(ICRS) implantation for visual rehabilitation of keratoconus.METHODS: A total of 42 eyes of 32 patients were included. After creation of intrastromal tunnels of 5.01±0.03 mm inner diameter, 5.71±0.03 mm outer diameter and at 384.21±34.12 μm depth, 1 or 2 ICRS of 150-300 μm thickness and 90°-210° arc length were implanted. Changes in uncorrected distance visual acuity(UDVA), corrected distance visual acuity(CDVA), refractive errors, mean simulated keratometry readings SimK_(avg), anterior and posterior corneal asphericity values(Q_(ant) and Q_(post), respectively) measured with Scheimpflug topography were evaluated retrospectively. RESULTS: There was a significant improvement in UDVA and CDVA, along with a significant decrease in refractive spherical equivalent(SE), cylinder and SimK_(avg) postoperatively(P〈0.001 for all). Mean Qant increased from-1.06±0.48 to-0.57±0.58 postoperatively(P〈0.001). Change in mean Qpost was insignificant(P=0.92). Postoperative changes in UDVA and CDVA were not correlated with the postoperative changes in SE and cylinder(P〉0.05 for all); but were correlated with the preoperative SimK_(avg) and Q_(ant) values(P〈0.001 for all). CONCLUSION: ICRS implantation seems to approximate the anterior corneal asphericity of "advanced prolate" shape to "optimal prolate" shape and an "ideal Q value" of-0.46; which may have a role in improved UDVA and CDVA postoperatively, besides decreased refractive cylinder values. 展开更多
关键词 cornea ectasia corneal asphericity intracomealring segments KERATOCONUS Q value
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Interchangeability of corneal curvature and asphericity measurements provided by three different devices 被引量:2
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作者 David P.Pinero Roberto Soto-Negro +2 位作者 Pedro Ruiz-Fortes Rafael J Pérez-Cambrodí Hideki Fukumitsu 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2019年第3期412-416,共5页
AIM: To evaluate the interchangeability of keratometric and asphericity measurements provided by three measurement systems based on different optical principles.METHODS: A total of 40 eyes of 40 patients with a mean a... AIM: To evaluate the interchangeability of keratometric and asphericity measurements provided by three measurement systems based on different optical principles.METHODS: A total of 40 eyes of 40 patients with a mean age of 34.1 y were included. In all cases, a corneal curvature analysis was performed with IOL-Master(IOLM), iDesign 2(ID2), and Sirius systems(SIR). Differences between instruments for flattest(K1) and steepest(K2) keratometric readings, as well as for magnitude and axis of corneal astigmatism were analyzed. Likewise, differences in asphericity(Q) between SIR and ID2 were also evaluated. RESULTS: Mean differences between devices for K1 were 0.20±0.21(P<0.001),-0.12±0.36(P=0.046) and-0.32±0.36 D(P<0.001) for the comparisons IOLM-SIR, IOLM-ID2 and SIR-ID2, respectively. The ranges of agreement for these comparisons between instruments were 0.41, 0.70, and 0.70 D. For K2, mean differences were 0.31±0.33(P<0.001),-0.08±0.43(P=0.265) and-0.39±0.38 D(P<0.001), with ranges of agreement of 0.65, 0.84, and 0.74 D. Concerning magnitude of astigmatism, ranges of agreement were in the limit of clinical relevance(0.49 D, P=0.011; 0.55 D, P=0.386; 0.43 D, P=0.05). In contrast, ranges of agreement were clinically relevant for astigmatic axis(26.68o, 33.83o and 18.37o, P≥0.121) and for Q between SIR and ID2(0.16, P<0.001). CONCLUSION: The keratometric corneal power, astigmatic axis and asphericity measurements provideby the three systems evaluated cannot be considered as interchangeable, whereas measurements of corneal astigmatism obtained with SIR and ID2 can be considered as interchangeable for clinical purposes. 展开更多
关键词 ASTIGMATISM corneal topography KERATOMETRY corneal asphericity
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Time Course of Q Value after Myopic Laser-assisted In Situ Keratomileusis
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作者 Zheng-wei Zhang Wei-ran Niu +2 位作者 Ming-ming Ma Ke-li-mu Jiang Bi-lian Ke 《Chinese Medical Sciences Journal》 CAS CSCD 2011年第3期141-145,共5页
Objective To assess the time course of Q value after myopic laser-assisted in situ keratomileusis(LASIK) and preliminarily evaluate the determinants of the difference of Q value between before and after LASIK.Methods ... Objective To assess the time course of Q value after myopic laser-assisted in situ keratomileusis(LASIK) and preliminarily evaluate the determinants of the difference of Q value between before and after LASIK.Methods We performed a retrospective,longitudinal investigation on patients undergoing wavefront optimized LASIK therapy for emmetropization.A total of 418 eyes from 222 cases were examined preoperatively,and partly followed up at one week(172 eyes),one month(134 eyes) and three months(51 eyes) after surgery.The horizontal,vertical and total Q values of cornea were calculated from eccentricity measured at the central 6-mm corneal zones respectively.Potential determinants of the change of Q value were analyzed using multiple linear regressions.Results The mean Q value was-0.17±0.13 preoperatively,and 0.99±0.70,0.97±0.66,and 0.86±0.41 one week,one and three months postoperatively,respectively.One way analysis of variance(ANOVA) demonstrated significant differences between measurements made before surgery and at all postoperative times(at one week,one and three months;all P<0.0001,Bonferroni post hoc),but no significant differences were found among postoperative groups.Significant differences of Q values between horizontal and vertical meridians were found before surgery and at all postoperative times(all P<0.0001).Multiple regression analysis revealed that change of Q value significantly correlated with manifest refraction spherical equivalent(r=0.116,P<0.0001) and axial length(r=0.264,P<0.0001).Conclusions Over the study period,the primary changes in Q value occur within 1 week after surgery,and then become slightly decreased and nearly stable.Manifest refraction spherical equivalent and axial length play a significant role in the change of postoperative Q value. 展开更多
关键词 corneal asphericity Q value MYOPIA laser-assisted in situ keratomileusis
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