Purpose
To implement a pure power vector method for monocular subjective refraction using a regular phoropter with the only modification being the inclusion of a Stokes lens. The proposed methodology ...was tested with three different Stokes lenses, and the results were compared with conventional clinical refraction procedures.
Methods
Power vector subjective refraction was performed by attaching a Stokes lens to the Risley prism holder. Stokes lenses allow for pure astigmatic compensation in the form of the J0, J45 components while the spherical lenses in the phoropter allow determination of the spherical component in the form of M (spherical equivalent). The proposed routine is presented step‐by‐step using three Stokes lenses having different astigmatic powers.
Results
Monocular subjective refraction was performed on 26 healthy subjects with a mean age of 44 ± 16 years, mean spherical equivalent of −0.56 D (range −5.50 to +2.38 D) and refractive astigmatism ≤1.50 D. No differences were found between the results obtained with the conventional technique versus the vector‐based procedure for the spherical equivalent (p = 0.28) or astigmatic components (p = 0.34). In addition, visual acuity (VA) was equivalent through the refractions measured with the conventional and vector procedures (p = 0.12). Repeatability coefficients for J0 and J45 with the new vector methodology were <0.38 D.
Conclusions
The proposed routine could be helpful for cases where it is difficult to get a valid starting point for conventional refraction (e.g., irregular corneas and media opacities), for testing facilities with limited resources/equipment and/or for motivated clinicians who wish to know about alternative methods of refractive error determination.
Purpose
To determine the long-term incidence of pseudophakic retinal detachment (PRD) after phacoemulsification and the weight of the main risk factors in the appearance of such complication in a ...large sample. To implement a customized formula and a software calculation program able to quantify the risk of suffering PRD applicable to all lens extraction patients.
Methods
Retrospective cumulative risk analysis conducted on 178,515 eyes operated under similar conditions in a group of refractive surgery clinics (Clínica Baviera SL) located in a relatively limited geographical area (Spain). A survival analysis was performed and the data were modelled using the Weibull regression to determine the risk over a period of 16 years and to estimate the association of different risk factors: sex, age, axial length (AXL) of the eye, intraoperative posterior capsule rents (PCR), and YAG laser capsulotomies. The resulting estimates were translated into a predictive equation for hazard rates and survival probabilities. Later, an application was developed to make prediction available for the clinical community in order to estimate the potential risk of any hypothetical case before lens surgery.
Results
Globally, 1521 (0.85%) cases of PRD were diagnosed during the period. The risk for PRD was significantly greater in males (5.48 2.94–10.2;
p
< 0.001), in long eyes (1.24 1.21–1.26;
p
< 0.001), and also after posterior capsule rents (13.97 11.61–16.82;
p
< 0.001). Posterior capsule rupture increased the risk of PRD up to fourteen times.
Conclusions
From weaker to stronger impact, age, axial length, sex, and intraoperative posterior capsule rent were significant risk factors for the appearance of PRD after lens extraction.
Purpose
Intraocular lens designs are constantly evolving, trying to obtain more spectacle independence after cataract surgery. This advantage can be linked to some disadvantages, such as optical ...quality decrease. For that reason, it is important to assess, not only the amount of vision provided but also the quality of vision once they are implanted. The purpose of the present work was to compare the visual performance between two monofocal intraocular models: a standard model and a monofocal with enhanced intermediate vision lens.
Methods
Prospective, randomized, comparative study. Sixty adult subjects scheduled to undergo bilateral cataract surgery and IOL implantation were randomized to receive one of the two IOLs in both eyes at Miranza IOA, Madrid, Spain (group A: monofocal with enhanced intermediate vision lens and group B: standard monofocal lens). Monocular outcomes (right eyes) determined 1 and 3 months postoperatively were photopic corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), perceived halo, corrected intermediate-distance contrast sensitivity, and higher-order aberrations. The impact of the new IOL in the postoperative management with autorefraction devices was also evaluated.
Results
No differences were found in CDVA between the two groups. Significant differences were detected between the two lenses evaluated in both total HOA (
p
= 0.028) and internal HOA (
p
= 0.037). Contrast sensitivity and halometry results obtained at 1 month were similar across the two IOL groups.
Conclusion
In patients undergoing cataract surgery, monofocal with enhanced intermediate vision IOL offered similar distance performance and contrast sensitivity along with perceived HOA and halos compared with the standard monofocal IOLs tested.
To evaluate visual function after bilateral implantation of a zonal refractive aspheric multifocal intraocular lens (IOL).
Private practice surgery center, Valencia, Spain.
Cohort study.
Consecutive ...eyes with cataract had bilateral implantation of Lentis Mplus LS-312 multifocal IOLs. Distance, intermediate, and near visual acuities; contrast sensitivity; defocus curves; and a quality-of-vision questionnaire, including presence of halos or dysphotopsia, were evaluated 6 months postoperatively. A control group of age-matched monofocal pseudophakic patients was included to compare contrast sensitivity function.
In the multifocal group, the mean binocular corrected distance visual acuity (logMAR) was -0.04 ± 0.07 at 6 m, 0.11 ± 0.10 at 1 m, and 0.06 ± 0.07 at 40 cm. The defocus curve showed little intermediate vision drop off. Photopic contrast sensitivity for distance was similar to the monofocal IOL contrast sensitivity function, while photopic contrast sensitivity for near and mesopic contrast sensitivity for distance with or without glare was reduced at high frequencies. The mean patient satisfaction was 8.09 ± 1.30 (scale 0 to 10); 84.4% of patients were completely independent of spectacles. Moderate halos, glare, and night-vision problems were reported by 6.2%, 12.5%, and 15.6% of patients, respectively.
The new-generation multifocal IOL provided adequate distance, intermediate, and, to a lesser extent, near vision with high rates of spectacle freedom. Halos occurred, and other photic phenomena should be expected in a small percentage of patients.
No author has a financial or proprietary interest in any material or method mentioned.
Purpose
In the event that any ocular parameter involved in the calculation of intraocular lens power could not be properly measured in one eye, it is important to know whether clinically relevant ...differences between both eyes can be expected. The aim of this work is to evaluate the symmetry of interocular biometric parameters.
Methods
This was a prospective, cross-sectional study involving 4090 subjects. Patients underwent consecutive swept-source optical biometry performed with an IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany). The biometric parameters that were evaluated were: axial length (AL), mean anterior curvature (Rm), anterior chamber depth (ACD), crystalline lens thickness (LT), central corneal thickness (CCT) and white-to-white (WTW). The Chang–Waring chord distance (CWC-D) and the Chang–Waring chord angle (CWC-A) were also evaluated.
Results
There is an excellent correlation between both eyes for almost all the biometric parameters under study, with the exception of the CWC. Agreement for AL was better for eyes shorter than 24 mm. The linearity of the OD-vs-OS relationship can be correctly assumed for all parameters (Cusum test:
p
> 0.05 in all cases).
Conclusion
There are no clinically significant interocular differences for the biometric parameters under study, although for all of them, except the LT, statistically significant differences did arise. In the case of AL, moderate differences can be expected in eyes larger than 24 mm.
To determine the intrasubject repeatability of a recently introduced dual-camera rotating Scheimpflug-Placido imaging system (Galilei G4) in determining corneal thickness, power, and wavefront ...aberrations in young healthy subjects.
University of Valencia, Valencia, Spain.
Prospective evaluation of diagnostic technology.
The study comprised right eyes of 25 subjects aged 20 to 40 years with a spherical equivalent ranging from -4.25 to +1.00 diopters. The central corneal thickness, thinnest point value and location, anterior and posterior surface curvatures, total corneal power, and corneal wavefront aberrations were measured for distance vision using the dual Scheimpflug-Placido system. Three consecutive measurements were taken in each eye.
Twenty-five eyes were evaluated. Repeated-measures analysis of variance showed the only statistically significant difference between the 3 repeated measures to be in trefoil aberration. Intraclass correlation coefficients (ICCs) were higher than 0.950 for all the parameters except the thinnest point chord distance to geometric corneal center (0.528) and chord angle (0.742), corneal astigmatism (0.811) and its vector components J0 (0.891) and J45 (0.724), and all wavefront aberrations.
The new dual Scheimpflug-Placido system had high intraobserver repeatability for corneal power and thickness and moderate repeatability for corneal astigmatism and corneal wavefront aberrations in healthy corneas with low astigmatism. This iteration of the device performed better in young healthy corneas than preceding versions.
No author has a financial or proprietary interest in any material or method mentioned.
To report the visual, refractive, and clinical outcomes of simultaneous topography-guided partial photorefractive keratectomy (PRK) and corneal collagen crosslinking (CXL) in eyes with keratoconus.
...Private practice surgery center, Dubai, United Arab Emirates.
Retrospective cohort study.
Refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, flat and steep keratometry (K) readings, and complications were evaluated 1, 3, 6, and 12 months postoperatively.
The study enrolled 31 eyes of 31 patients aged 21 to 42 years. All study parameters showed a statistically significant improvement at 3, 6, and 12 months over baseline values. At 12 months, the mean UDVA improved to 0.23 logMAR±0.33 (SD) from 0.79±0.36 logMAR (P<.001) and the CDVA improved to 0.06±0.07 logMAR from 0.28±0.20 logMAR (P<.001). The mean defocus decreased from 3.45±1.60 diopters (D) to 1.88±1.58 D (P<.001). The flat K and steep K readings showed significant flattening. The mean refractive astigmatism decreased from -2.77±1.47 D to -0.98±0.76 D (P<.001). The improvement in study parameters plateaued after 3 months.
Simultaneous topography-guided partial PRK and CXL was effective, safe, and stable in keratoconus patients.
No author has a financial or proprietary interest in any material or method mentioned.
Compare subjective (Rx) and objective (ObjRx) refractions outcomes with two autorefractors models and an aberrometer in eyes implanted with a hydrophobic trifocal IOL (FineVision POD F GF, Physiol, ...Liége, Belgium) and a hydrophilic one (FineVision POD F, Physiol, Liége, Belgium).
Prospective comparative cohort study, with 100 subjects randomly assigned to either the POD F group (n = 50) or the POD F-GF group (n = 50). Postoperative eye examinations at 1-month visit included seven result sets, one for each assessment method: Rx, AR (automated refraction measured with the autorefractor KR8800), WF-P (Zernike-coefficients-based objective refraction, photopic pupil size), WF-M (Zernike-coefficients-based objective refraction, mesopic pupil size), WF-4 (Zernike-coefficients-based objective refraction, 4 mm pupil), OPD-C (automated refraction measured with the aberrometer OPD in the central pupil/photopic conditions), and OPD-M (automated refraction measured with the aberrometer OPD under mesopic conditions).
Mean differences between ObjRx and Rx reached statistical significance for sphere and spherical equivalent (M) only with OPD-C in the POD F-GF group. All ObjRx methods showed significant differences with Rx in the POD F group, with some values differing by more than 0.50 D (−0.58 D in M for the WF-P). Bland Altman plots showed better agreement for the astigmatic components, and for sphere and spherical equivalents in both IOL groups measured with AR and OPD-M.
None of the objective methods of refraction evaluated in this study were as reliable as the subjective refraction, irrespective of the lens material, but POD F-GF ObjRx seems to differ less with Rx than POD F ObjRx values.
This study is to evaluate the optical characteristics of a non-diffractive wavefront-shaping intraocular lens which incorporates surface refractive modifications for shaping the wavefront in order to ...achieve extended depth of focus (EDoF) and to assess whether the nominal power of this IOL influences the attainable add power.
A commercially available optical bench NIMO TR1504 device (LAMBDA-X, Nivelles, Belgium) was employed to obtain full optical characterization of three non-diffractive EDoF intraocular lenses with + 10 D, + 20 D, and + 30 D powers. After NIMO measurements, data were computed using a custom-made MATLAB program (Mathworks, Inc., Natick, MA, USA) to evaluate the optical quality functions, such as the point spread function (PSF), wavefront profiles, and modulation transfer function (MTF) for two pupil sizes: 3 mm and 4.0 mm.
The non-diffractive EDoF intraocular lens showed a central serrated power profile behavior with additions of + 2.00 to + 2.50 D over the nominal power. Higher order aberrations were found to be driven mainly by the spherical aberration, with almost null comatic influence. Optical quality metrics showed good values, better for a 3 mm pupil compared to a 4.5 mm one, as expected. The three IOL powers tested showed a very similar behavior in terms of power and aberrometric profiles, with minimal to null differences related to the nominal power.
The non-diffractive wavefront-shaping EDoF intraocular lens achieves a near addition up to + 2.50 D aiming for an extended range of vision, almost independently of the base power.
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