Dysfunctional lens syndrome (DLS) is a term coined to describe the natural aging changes in the crystalline lens. Different alterations in the refractive properties and transparency of the lens are produced during the development of presbyopia and cataract, such as changes in internal high order aberrations or an increase in ocular forward scattering, with a potentially significant impact on clinical measures, including visual acuity and contrast sensitivity. Objective technologies have emerged to solve the limits of current methods for the grading of the lens aging, which have been linked to the DLS term. However, there is still not a gold standard or evidence-based clinical guidelines around these new technologies despite multiple research studies have correlated their results with conventional methods such as visual acuity or the lens opacification system (LOCS), with more scientific background around the ocular scattering index (OSI) and Scheimpflug densitometry. In either case, DLS is not a new evidence-based concept that leads to new knowledge about crystalline lens aging but it is a nomenclature change of two existing terms, presbyopia and cataracts. Therefore, this term should be used with caution in the scientific peer-reviewed literature.

/pdf/from-presbyopia-to-cataracts-a-critical-review-on-11fcw813n4.pdf

From Presbyopia to Cataracts: A Critical Review on Dysfunctional Lens Syndrome

A rapid and user-friendly assay to detect the Neutrophil gelatinase-associated lipocalin (NGAL) using up-converting nanoparticles.

Background To compare the correction effect and optical quality after small-incision lenticule extraction (SMILE) and femtosecond laser assisted laser in situ keratomileusis (FS-LASIK) for high myopia. Methods 51 high myopia eyes after SMILE and 49 high myopia eyes after FS-LASIK were enrolled and divided into two groups retrospectively. The OQAS and iTrace analyzer were used for optical quality inspection. Between the two groups the spherical equivalent (SE), astigmatism, uncorrected distant visual acuity (UDVA), strehl ratio (SR), modulation transfer function cutoff frequency (MTF cutoff), objective scatter index (OSI) and wavefront aberrations were analyzed and compared before surgery and at 1, 6 and 12 months after surgery. Results After the operation: (1) SE and astigmatism declined and UDVA increased significantly in both groups, and UDVA was better after SMILE than FS-LASIK. (2) SR and MTF cutoff reduced and OSI increased significantly after SMILE and FS-LASIK. SR and MTF cutoff were significantly higher after SMILE than FS-LASIK. OSI was significantly lower after SMILE than FS-LASIK. (3) The total wavefront aberration, total low-order wavefront aberration, defocus and astigmatism aberration as well as trefoil aberration reduced significantly in both groups. The total high-order wavefront aberration increased significantly after FS-LASIK. The spherical and coma aberration increased significantly in both groups. The total high-order wavefront aberration and coma aberration at 1 month were higher after FS-LASIK than SMILE. Conclusion The optical quality descended after SMILE and FS-LASIK. SMILE was superior to FS-LASIK at the correction effect and optical quality for high myopia. The combination of OQAS and iTrace analyzer is a valuable complementary measurement in evaluating the optical quality after the refractive surgery. Trial registration This is a retrospective study. This research was approved by the ethics committee of Xiangya Hospital and the IRB approval number is 201612074.

/pdf/comparison-of-the-optical-quality-after-smile-and-fs-lasik-2q1d8rcrzz.pdf

Comparison of the optical quality after SMILE and FS-LASIK for high myopia by OQAS and iTrace analyzer: a one-year retrospective study.

To assess repeatability and agreement of the Pentacam AXL Wave with that of the iTrace aberrometer.Narayana Nethralaya, Bangalore, India.Prospective, cross-sectional study.All eyes of patients underwent 3 sets of measurements at a single visit, using Pentacam AXL Wave and iTrace. Lower-order aberrations (LOAs), higher-order aberrations (HOAs), and coma and spherical aberrations (SAs) were analyzed. Repeatability was assessed using within-subject (Sw) SD, test-retest variability (TRT), Sw coefficient of variation (CoV), and intraclass correlation coefficient (ICC). The Bland-Altman analysis was used to assess 95% limits of agreement (LoA) and the correlation coefficient (r) to determine strength of relationship between measurements.100 eyes of 100 patients underwent measurements. Pentacam AXL Wave had repeatability with an ICC for total ocular aberrations ranging from 0.84 for HOAs to 0.92 for LOAs and for corneal from 0.76 for HOAs to 0.86 for LOAs. The Sw, TRT, and CoV of all aberrations were significantly lower (better) than those of iTrace (P < .001). The mean differences between 2 devices were insignificant for the comparison of all parameters, except for spherical aberration (0.011 [0.002571 to 0.02008]; P = .01). Both devices showed excellent correlations for ocular aberrations (total HOAs [P = .12, LoA = -0.52 to 0.025; r = 0.89]; LOAs [P = .14, LoA = -2.71 to 2.61; r = 0.96]; coma [P = .27, LoA = -0.11 to 0.12; r = 0.89]; and SA [P = .01, LoA = -0.09 to 0.07; r = 0.97]).The repeatability estimates for wavefront aberrations using Pentacam AXL Wave were significantly better than those using iTrace. Both devices showed excellent correlations for total ocular aberrations. 

Repeatability and agreement of wavefront aberrations of a new hybrid topographer and aberrometer in healthy eyes

Purpose To compare the difference and agreement of corneal higher-order aberrations (HOAs) in keratoconic eyes using Scheimpflug and dual Scheimpflug–Placido imaging systems. Setting Emory University, Atlanta, Georgia, and the University of Southern California, Los Angeles, California, USA. Design Retrospective between-devices reliability and agreement study. Methods Patients diagnosed with keratoconus were evaluated sequentially by Scheimpflug and dual Scheimpflug–Placido devices. Differences, correlations, and agreement between values for total root mean square (RMS), trefoil, coma, and spherical aberration were analyzed, and Bland-Altman plots were generated. Results Fifty eyes from 50 patients (31 men, 19 women) were evaluated. Trefoil at 30 degrees, spherical aberration, and total RMS were significantly different between groups (P  Conclusion Significant differences were found between measurements of corneal HOAs generated by Scheimpflug and dual Scheimpflug–Placido devices in patients with keratoconus, with generally limited correlations and wide LoA. HOAs measurements from these devices should not be considered equivalent.

Corneal higher-order aberrations measurements: Comparison between Scheimpflug and dual Scheimpflug–Placido technology in keratoconic eyes

AIM To compare the difference and agreement of KR-1W and iTrace for measurement of high order aberrations. METHODS KR-1W and iTrace were respectively used in a group of healthy people (40 volunteers, 32 eyes) to measure the high order aberration (HOA) of corneal, internal and total ocular. The clinical difference and agreement of two instruments were respectively evaluated by paired-samples t-test and Bland-Altman analysis. RESULTS The paired-samples t-test showed that the corneal HOA measured by the two instruments had no statistical differences (P>0.05); but the internal and total ocular HOA had significant statistical differences (P<0.05), and the mean results measured by iTrace were higher than that of KR-1W. However, Bland-Altman analysis revealed that the HOA of corneal and internal were all in 95% limits of agreement; and just one point of total ocular HOA was beyond the 95% limits of agreement. CONCLUSION KR-1W and iTrace were consistent well in the measurement of corneal, internal and total ocular HOA, especially for the cornea.

Comparison of two types of visual quality analyzer for the measurement of high order aberrations.

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Comparison of two types of visual quality analyzer for the measurement of high order aberrations.