Intra‐observer repeatability of optical quality measures provided by a double‐pass system

Five-Year Follow-Up of Visual Outcomes and Optical Quality After Small Incision Lenticule Extraction for Moderate and High Myopia

Introduction

This study investigated the long-term visual and optical quality changes after small incision lenticule extraction (SMILE) for the correction of moderate to high myopia.

Methods

Forty-one eyes of 41 patients with a mean spherical equivalent (SE) of − 6.74 ± 1.45 D undergoing SMILE were enrolled. Preoperative and 1-month, 3-month, 1-year and 5-year postoperative follow-up examinations were performed including visual acuity, manifest refraction, corneal aberrations and contrast sensitivity. An optical quality analysis system was used to measure objective scatter index (OSI), Strehl ratio (SR) and modulation transfer function cutoff frequency (MTF_cutoff).

Results

The safety and efficacy indices were 1.09 ± 0.12 and 1.03 ± 0.17, respectively, at the 5-year follow-up. No significant changes in SE from 1 month to 5 years postoperatively were found. The OSI significantly increased at 1 and 3 months postoperatively (p < 0.01 and p < 0.01) and declined at 1 and 5 years (p = 0.81 and p = 0.87). MTF_cutoff and SR showed similar trends. Coma, spherical aberration and total higher-order aberration significantly increased after SMILE (p < 0.01) and remained stable from 1 month to 5 years after surgery (p > 0.05). Contrast sensitivity in the photopic and mesopic condition showed no significant changes during 5-year follow-up (p > 0.05).

Conclusion

The SMILE procedure is satisfactory in terms of optical quality for correcting moderate and high myopia in the long-term period.

Trial Registration

ChiCTR-ONRC-13003114.

Objective and subjective visual quality after implantation of all optic zone diffractive multifocal intraocular lenses: a prospective, case-control observational study

BACKGROUND AND AIMS

To evaluate the objective and subjective optical quality of all optic zone diffractive multifocal intraocular lens (IOL).

METHODS

Fifty patients (50 eyes) having phacoemulsification and IOL implantation surgery were enrolled. 25 patients were implanted with all optic zone diffractive multifocal IOL and 25 patients with monofocal IOL. Objective optical quality parameters under 4 mm pupil using Optical Quality Analysis System (OQAS), subjective visual acuity (VA) at 85 cd/m² luminance and questionnaire concerning halo and visual function were assessed.

RESULTS

The multifocal group gained similar objective optical outcomes, such as OQAS values at contrast 100%, 20%, 9%, modulation transfer function cut-off and Strehl ratio, as the monofocal group. Objective scatter index (OSI) was significantly better in the monofocal group. Distance corrected near VA, uncorrected near VA, distance corrected intermediate VA and uncorrected intermediate VA were significantly better in the multifocal group. The difference in uncorrected distance VA and best corrected distance VA between the monofocal and multifocal groups was not significant. Mild halos and glare were reported in both groups and a significant difference between the two groups was not observed; however, moderate glare and halos were reported only in the multifocal group (2/25). There was no significant difference between the two groups when visual function was compared.

CONCLUSIONS

All optic zone diffractive multifocal IOLs provided almost the same objective optical quality as monofocal IOLs did under 4 mm pupil besides good all distance visual performance, but with greater OSI, indicating that implantation provides good optical quality in daytime but with more intraocular scatter light.

TRIAL REGISTRATION NUMBER

NCT02234635, post-results.

Intra- and Intersession Repeatability of an Optical Quality and Intraocular Scattering Measurement System in Children

Purpose

To evaluate intra- and intersession repeatability of objective optical quality and intraocular scattering measurements with a double-pass system in children.

Methods

Forty-two eyes of 42 children were included in the study. An optical quality analysis system (OQAS) was used to measure optical quality parameters, including modulation transfer function cutoff frequency (MTF_cutoff), Strehl ratio (SR), OQAS values (OV) at 3 different contrasts and objective scatter index (OSI). Three measurement sessions with 10-min intervals were operated by the same technician, and in each session four consecutive measurements were obtained.

Results

Mean values for MTF_cutoff, SR and OSI were 46.85 ± 7.45cpd, 0.27 ± 0.06 and 0.34 ± 0.22 respectively. 1) The intraclass correlation coefficients were ranged from 0.89 to 0.97 and coefficients of variation from 0.06 to 0.16 for all the parameters in the first session; the relative repeatability were 11.1% (MTF_cutoff), 22.5% (SR), 10.9% (OV100%), 16.6% (OV2%), 22.4% (OV9%) and 56.3% (OSI). Similar results were found in the second and third sessions. 2) Bland-Altman analysis showed that narrow 95% confidence intervals (compared between the first and second sessions) ranged from -5.42 to 5.28 (MTF_cutoff), -0.05 to 0.07 (SR), -0.18 to 0.18 (OV100%), -0.26 to 0.29 (OV20%), -0.33 to 0.39 (OV9%) and -0.11 to 0.09 (OSI); the comparison between any two of the three sessions showed similar results.

Conclusion

Measurements of optical quality and intraocular scattering in children by the double-pass system showed good intra- and intersession repeatability. Retinal image quality is high and intraocular scattering is low in children.

Reproducibility of optical quality parameters measured at objective and subjective best focuses in a double-pass system

AIM

To evaluate intra-session repeatability and reproducibility of optical quality parameters measured at objective and subjective best focuses in a double-pass system.

METHODS

Thirty Chinese healthy adults (19 to 40 years old) meeting our inclusion criterion were enrolled in the study. After a basic eye examination, two methods of optical quality measurement, based on subjective and objective best focuses were performed using the Optical Quality Analysis System (OQAS) with an artificial pupil diameter of 4.0 mm.

RESULTS

With each method, three consecutive measurements of the following parameters: the modulation transfer function cutoff frequency (MTFcutoff), the Strehl(2D) ratio, the OQAS values (OVs) at contrasts of 100%, 20%, 9% and the objective scatter index (OSI) were performed by an experienced examiner. The repeatability of each method was evaluated by the repeatability limit (RL) and the coefficient of repeatability (COR). Reproducibility of the two methods was evaluated by intra-class correlation coefficient (ICC) and the 95% limits of agreement (Bland and Altman analysis). Thirty subjects, seven females and twenty three males, of whom 15 right eyes and 15 left eyes were selected randomly for recruitment in the study. The RLs (percentage) for the six parameters measured at objective focus and subjective focus ranged from 8.44% to 15.13% and 10.85% to 16.26%, respectively. The CORs for the two measurement methods ranged from 8.27% to 14.83% and 10.63% to 15.93%, respectively. With regard to reproducibility, the ICCs for the six parameters of OQAS ranged from 0.024 to 0.276. The 95% limits of agreement obtained for the six parameters (in comparison of the two methods) ranged from -0.57 to 42.18 (MTFcutoff), -0.01 to 0.23 (Strehl(2D) ratio), -0.02 to 1.40 (OV100%), -0.10 to 1.75 (OV20%), -0.14 to 1.80 (OV9%) and -1.46 to 0.18 (OSI).

CONCLUSION

Measurements provided by OQAS with either method showed a good repeatability. However, the results obtained from the two different measurement methods showed a poor reproducibility. These findings suggest that it might be best to evaluate patients' optical quality by OQAS using the best focus as chosen automatically by the instrument.

[Quality of vision studied by comparative measurement of light scattering]

PURPOSE

To assess quality of vision by measuring ocular light scattering with two platforms and comparing them to traditional tests, in healthy subjects and cataract patients.

PATIENTS AND METHODS

One hundred and sixty-eight eyes divided in two groups were examined by the same clinician in a prospective study (group 1, healthy controls, with a mean age of 31.22 [± 6.76]; and group 2, patients presenting with cataract, with a mean age of 60.36 [± 10.27]). Patients with ocular surface disease were excluded from this study. Each group responded to the VF-14 questionnaire, underwent an examination with lens opacities assessed by LOCS III and a measurement of ocular light scattering with two platforms: the OQAS (Visiometrics(©)) and the C-Quant (Oculus(©)). We analyzed correlations between indices of light scattering with the two platforms (respectively OSI and log(s)) and traditional quality of vision tests (VF-14 questionnaire and LOCS III).

RESULTS

Strong correlations were found between the OSI and LOCS III. Moderate correlations were found between the OSI and the VF-14 questionnaire, as well as between log(s), VF-14 questionnaire and LOCS III.

CONCLUSION

Indices of light scattering seems to be valid tools to assess quality of vision, thus lending themselves to routine testing of visual function.

Double-pass system assessing the optical quality of pseudophakic eyes

PURPOSE

To compare the optical quality measurements obtained from the double-pass system and ocular aberrations, subjective visual acuity, and contrast sensitivity score in pseudophakic eyes.

METHODS

Three months after cataract surgery, modulation transfer function (MTF) cutoff frequency, Strehl ratio, objective scatter index, and objective pseudoaccommodation obtained from the double-pass system were compared with total aberration, higher-order aberration, and spherical aberration obtained from ray-tracing aberrometer. In addition, parameters of the double-pass system were compared with subjective visual acuity and the contrast sensitivity score.

RESULTS

Forty eyes of 40 patients were included. The MTF cutoff frequency and Strehl ratio were negatively correlated with total aberration (r = -0.503, p = 0.003; r = -0.509, p = 0.003, respectively) and subjective visual acuity (r = -0.453, p = 0.007; r = -0.354, p = 0.040, respectively). The objective scatter index was positively correlated with total aberration (r = 0.451, p = 0.024) and subjective visual acuity (r = 0.516, p = 0.008). The MTF cutoff frequency showed a correlation with contrast sensitivity score under photopic and mesopic conditions.

CONCLUSIONS

Optical quality parameters obtained from the double-pass system were correlated with ocular aberrations, subjective visual acuity, and contrast sensitivity score in pseudophakic eyes.

Statistical guidelines for the analysis of data obtained from one or both eyes

PURPOSE

Measurements obtained from the right and left eye of a subject are often correlated whereas many statistical tests assume observations in a sample are independent. Hence, data collected from both eyes cannot be combined without taking this correlation into account. Current practice is reviewed with reference to articles published in three optometry journals, viz., Ophthalmic and Physiological Optics (OPO), Optometry and Vision Science (OVS), Clinical and Experimental Optometry (CEO) during the period 2009-2012.

RECENT FINDINGS

Of the 230 articles reviewed, 148/230 (64%) obtained data from one eye and 82/230 (36%) from both eyes. Of the 148 one-eye articles, the right eye, left eye, a randomly selected eye, the better eye, the worse or diseased eye, or the dominant eye were all used as selection criteria. Of the 82 two-eye articles, the analysis utilized data from: (1) one eye only rejecting data from the adjacent eye, (2) both eyes separately, (3) both eyes taking into account the correlation between eyes, or (4) both eyes using one eye as a treated or diseased eye, the other acting as a control. In a proportion of studies, data were combined from both eyes without correction.

SUMMARY

It is suggested that: (1) investigators should consider whether it is advantageous to collect data from both eyes, (2) if one eye is studied and both are eligible, then it should be chosen at random, and (3) two-eye data can be analysed incorporating eyes as a 'within subjects' factor.