Comparison of Subjective Refraction under Binocular and Monocular Conditions in Myopic Subjects

To compare subjective refraction under binocular and monocular conditions, and to investigate the clinical factors affecting the difference in spherical refraction between the two conditions. We examined thirty eyes of 30 healthy subjects. Binocular and monocular refraction without cycloplegia was measured through circular polarizing lenses in both eyes, using the Landolt-C chart of the 3D visual function trainer-ORTe. Stepwise multiple regression analysis was used to assess the relations among several pairs of variables and the difference in spherical refraction in binocular and monocular conditions. Subjective spherical refraction in the monocular condition was significantly more myopic than that in the binocular condition (p < 0.001), whereas no significant differences were seen in subjective cylindrical refraction (p = 0.99). The explanatory variable relevant to the difference in spherical refraction between binocular and monocular conditions was the binocular spherical refraction (p = 0.032, partial regression coefficient B = 0.029) (adjusted R² = 0.230). No significant correlation was seen with other clinical factors. Subjective spherical refraction in the monocular condition was significantly more myopic than that in the binocular condition. Eyes with higher degrees of myopia are more predisposed to show the large difference in spherical refraction between these two conditions.

Effect of Intraocular Forward Scattering and Corneal Higher-Order Aberrations on Visual Acuity after Descemet's Stripping Automated Endothelial Keratoplasty

Purpose

To assess the relationship of intraocular forward scattering and corneal higher-order aberrations (HOAs) with best spectacle corrected visual acuity (BSCVA) after Descemet’s stripping automated endothelial keratoplasty (DSAEK), and to compare these parameters between DSAEK and non-Descemet’s stripping automated endothelial keratoplasty (n-DSAEK) groups.

Methods

This retrospective study enrolled thirty eyes of 30 consecutive patients who underwent standard DSAEK, and who underwent successful phacoemulsification with intraocular lens implantation before DSAEK. The mean age at the time of surgery was 71.7 ± 10.4 years. We quantitatively evaluated the objective scattering index (OSI) using the double-pass instrument (OQAS II, Visiometrics) and corneal HOAs using Hartmann-Shack aberrometry (KR-9000PW, Topcon) 3 months postoperatively.

Results

The mean OSI, corneal HOAs, and logMAR BSCVA 3 months after DSAEK were 7.91 ± 3.58, 0.43 ± 0.27 μm, and 0.32 ± 0.25, respectively. We found a significant correlation between the OSI and logMAR BSCVA (Spearman correlation coefficient r=0.714, p<0.001), but no significant association between corneal HOAs and logMAR BSCVA 3 months postoperatively (r=0.209, p=0.267). We found no significant differences in any postoperative parameters between the DSAEK and n-DSAEK groups (p>0.05).

Conclusions

Our pilot study demonstrated that the postoperative corrected visual acuity was significantly correlated with intraocular forward scattering, but not with corneal HOAs in post-DSAEK eyes, suggesting that intraocular forward scattering plays a more essential role in postoperative visual performance than corneal aberrations after DSAEK. The detailed visual performance, such as HOAs and intraocular scattering, after n-DSAEK appears to be essentially equivalent to that after DSAEK.

Effect of femtosecond laser setting on visual performance after small-incision lenticule extraction for myopia

AIM

To compare the effect of the two femtosecond laser settings on visual performance after small-incision lenticule extraction (SMILE) for myopia and myopic astigmatism.

METHODS

Forty-four eyes of 22 consecutive patients who underwent SMILE with an energy level of 140 nJ (spot distance 3.0 µm) in one eye, and with an energy level of 170 nJ (spot distance 4.5 µm) in the other eye, the eyes being randomly assigned. Preoperatively, 1 week, and 1 and 3 months postoperatively, the values of the modulation transfer function (MTF) cutoff frequency, Strehl ratio, objective scattering index (OSI) and Optical Quality Analysis System (OQAS) values (OVs) for these eyes were quantitatively assessed using an Optical Quality Analysis System (Visiometrics).

RESULTS

No significant differences were detected between the two groups in the visual and refractive outcomes, or in the MTF cutoff frequency, the Strehl ratio, the OSI, the OV 100%, the OV 20% or the OV 9% at any time point before or after surgery.

CONCLUSIONS

SMILE with energy settings of 140 and 170 nJ was effective for the correction of myopia and myopic astigmatism. It is indicated that the differences in laser setting (140 nJ, spot distance 3.0 µm vs 170 nJ, spot distance 4.5 µm) did not significantly affect the optical quality including the intraocular scattering of eyes undergoing SMILE.

CLINICAL TRIAL NUMBER

The protocol was registered with University Hospital Medical Information Network Clinical Trial Registry (UMIN000016241).

Comparison of astigmatic correction after femtosecond lenticule extraction and wavefront-guided LASIK for myopic astigmatism

PURPOSE

To compare postoperative astigmatic correction between femtosecond lenticule extraction (FLEx) and wavefront-guided LASIK in eyes with myopic astigmatism.

METHODS

Fifty-eight eyes of 41 patients undergoing FLEx and 49 eyes of 29 patients undergoing wavefront-guided LASIK to correct myopic astigmatism were examined. Visual acuity, cylindrical refraction, predictability of the astigmatic correction, and astigmatic vector components were compared between groups 6 months after surgery.

RESULTS

There was no statistically significant difference in manifest cylindrical refraction (P = .08) or percentage of eyes within ± 0.50 diopter (D) of its refraction (P = .11) between the surgical procedures. The index of success in FLEx was statistically significantly better than that of wavefront-guided LASIK (P = .02), although there was no significant difference between the groups in other indices (eg, surgically induced astigmatism, target-induced astigmatism, astigmatic correction index, angle of error, difference vector, and flattening index). Subgroup analysis showed that FLEx had a better index of success (P = .02) and difference vector (P = .04) than wavefront-guided LASIK in the low cylinder subgroup; the angle of error in FLEx was significantly smaller than that of wavefront-guided LASIK in the moderate cylinder subgroup (P = .03).

CONCLUSIONS

Both FLEx and wavefront-guided LASIK worked well for the correction of myopic astigmatism by the 6-month follow-up visit. Although FLEx had a better index of success than wavefront-guided LASIK when using vector analysis, it appears equivalent to wavefront-guided LASIK in terms of visual acuity and the correction of astigmatism.

Factors influencing contrast sensitivity function in myopic eyes

Purpose

To evaluate the factors affecting the area under the log contrast sensitivity function (AULCSF) in healthy myopic eyes.

Methods

We retrospectively examined 201 eyes of 201 consecutive subjects (age, 31.8±7.4 years (mean ± standard deviation)) with myopic refractive errors of −1.25 to −8.25 diopters (D). From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. Stepwise multiple regression analysis was used to assess the factors affecting the AULCSF.

Results

The mean AULSCF was 1.09±0.09 (0.89 to 1.55). Explanatory variables relevant to the AULCSF were, in order of influence, the objective scattering index (OSI) (p = 0.018, partial regression coefficient B = –0.032) and logMAR CDVA (p = 0.022, B = –0.209) (adjusted R² = 0.231). No significant correlation was seen with other clinical factors such as gender, manifest refraction, pupil size, lens density, corneal HOAs, or ocular HOAs.

Conclusions

Although the great majority of the variance remains unexplained, eyes with lower OSI and better CDVA are more predisposed to show higher contrast sensitivity function. These results indicate that not only CDVA but also intraocular forward scattering may play some role in predicting the contrast sensitivity function in myopic subjects.

Three-year follow-up of posterior chamber toric phakic intraocular lens implantation for the correction of high myopic astigmatism in eyes with keratoconus

AIM

To assess the clinical outcomes following the use of toric implantable collamer lenses (toric ICL, STAAR Surgical) for the correction of high myopic astigmatism with keratoconus.

METHODS

This retrospective study evaluated 21 eyes of 11 patients with spherical equivalents of -9.70±2.33 D (mean±SD) and astigmatism of -3.21±1.56 D who underwent toric ICL implantation for keratoconus. Preoperatively, and at 1, 3 and 6 months and 1, 2 and 3 years postoperatively, we assessed the safety, efficacy, predictability, stability and adverse events of the surgery.

RESULTS

The logarithm of the minimum angle of resolution (logMAR) uncorrected distance visual acuity (UDVA) and the logMAR corrected distance visual acuity (CDVA) were -0.06±0.11 and -0.12±0.09, respectively, at 3 years postoperatively. At 3 years, 67% and 86% of the eyes were within ±0.5 and ±1.0 D, respectively, of the targeted correction. Manifest refraction changes of 0.04±0.33 D occurred from 1 month to 3 years postoperatively. No significant change in manifest refraction (analysis of variance, p=0.989) or keratometry (p=0.951), or vision-threatening complications occurred during the observation period.

CONCLUSIONS

Toric ICL implantation is beneficial according to measures of safety, efficacy, predictability and stability for the correction of refractive errors for keratoconus during a 3-year observation period. The disease did not progress even in the late-postoperative period, suggesting the viability of this procedure as a surgical option for the treatment of such eyes.

Clinical outcomes of penetrating keratoplasty performed with the VisuMax femtosecond laser system and comparison with conventional penetrating keratoplasty

PURPOSE

To assess the clinical outcomes of femtosecond laser-assisted keratoplasty (FLAK) using the VisuMax femtosecond laser system, and to compare them with those of conventional penetrating keratoplasty (PK).

METHODS

We retrospectively examined 20 eyes of 20 consecutive patients undergoing FLAK and 20 eyes of 20 age- and diagnosis-matched patients undergoing conventional PK. We quantitatively assessed corneal astigmatism, refractive astigmatism, and corrected visual acuity, 1, 3, and 6 months postoperatively, and endothelial cell density 6 months postoperatively.

RESULTS

Corneal and refractive astigmatism after FLAK were significantly lower after FLAK than that after conventional PK at 3 and 6 months postoperatively (p = 0.04 and p = 0.03, respectively, Mann-Whitney U test). FLAK provided significantly faster visual recovery than conventional PK at 1 month postoperatively (p = 0.02), but not at 3 and 6 months postoperatively (p = 0.52 and p = 0.80, respectively). We found no significant differences in the change in endothelial cell density between the two groups (p = 0.30).

CONCLUSIONS

FLAK using the VisuMax femtosecond laser system induces significantly less corneal and refractive astigmatism than conventional PK, and provides significantly faster visual recovery in the early postoperative period, possibly because the geometry of the donor-recipient matching is more physiological and requires less tight sutures. It is suggested that FLAK has advantages over conventional PK, in terms of astigmatism and fast visual recovery.

Wavefront-guided versus non-wavefront-guided photorefractive keratectomy for myopia: meta-analysis of randomized controlled trials

Purpose

To compare the efficacy, predictability, safety, and induced higher-order aberrations (HOAs) between wavefront-guided and non-wavefront-guided photorefractive keratectomy (PRK).

Methods

The Cochrane Central Register of Controlled Trials, PubMED, and EMBASE were searched for randomized controlled trials. Trials meeting the selection criteria were quality appraised, and data was extracted by 2 independent authors. Measures of association were pooled quantitatively using meta-analytical methods. Comparisons between wavefront-guided and non-wavefront-guided ablations were made as pooled odds ratios (ORs) or weighted mean differences. The pooled ORs and 95% confidence intervals (CIs) were computed for efficacy, safety, and predictability. The weighted mean differences and 95% CIs were used to compare induced HOAs.

Results

The study covered five trials involving 298 eyes. After wavefront-guided PRK, the pooled OR of achieving an uncorrected distance visual acuity of 20/20 (efficacy) was 1.18 (95% CI, 0.53–2.60; p = 0.69), the pooled OR of achieving a result within ±0.50 diopter of the intended target (predictability) was 0.86 (95% CI, 0.40–1.84; p = 0.70). No study reported a loss of 2 or more lines of Snellen acuity (safety) with either modality. In eyes with wavefront-guided PRK, the postoperative trefoil aberrations (mean difference −0.02; 95% CI, −0.03 to −0.00; p = 0.03) were significantly lower. There were no significant differences between the two groups in the postoperative total HOAs (mean difference −0.04; 95% CI, −0.23 to 0.14; p = 0.63), spherical (mean difference 0.00; 95% CI, −0.08 to 0.09; p = 0.93), and coma (mean difference −0.06; 95% CI, −0.14 to 0.03; p = 0.20) aberrations.

Conclusions

According to the meta-analysis, wavefront-guided PRK offered no advantage in efficacy, predictability, or safety measures over non-wavefront-guided PRK, although it may have induced fewer trefoil aberrations.

Factors influencing long-term regression after posterior chamber phakic intraocular lens implantation for moderate to high myopia

PURPOSE

To evaluate the factors affecting the long-term regression after posterior chamber phakic intraocular lens (Visian ICL; STAAR Surgical) implantation for myopia.

DESIGN

Retrospective observational case series.

METHODS

We retrospectively examined 60 eyes of 35 consecutive patients (age, 38.4 ± 9.3 years [mean ± standard deviation]) with myopic refractive errors of -4.00 to -15.25 diopters (D) undergoing ICL implantation. We assessed the amount of myopic regression from 1 month to 6 years after surgery. Stepwise multiple regression analysis was used to assess the factors affecting the amount of myopic regression.

RESULTS

The mean myopic regression from 1 month to 6 years after surgery was -0.33 ± 0.71 D (0.75 to -3.00 D). Explanatory variables relevant to the myopic regression were, in order of influence, patient age (partial regression coefficient B = -0.042, P < .0001) and preoperative axial length (B = -0.186, P = .013) (adjusted R(2) = 0.300). No significant correlation was seen with other clinical factors such as sex, preoperative refraction, intraocular pressure, white-to-white distance, anterior chamber depth, central corneal thickness, or mean keratometric readings.

CONCLUSIONS

Although the great majority of the variance remains unexplained, eyes of older patients and eyes with longer axial length are more predisposed to show greater myopic regression after ICL implantation. These results indicate that not only patient age but also axial length may play some role in predicting the long-term refractive outcomes of this surgical procedure.

Visual and refractive outcomes of femtosecond lenticule extraction and small-incision lenticule extraction for myopia

PURPOSE

To compare the visual and refractive outcomes of femtosecond lenticule extraction (FLEx) and small-incision lenticule extraction (SMILE) in eyes with myopia.

DESIGN

Prospective, randomized, masked clinical trial with intraindividual comparison.

METHODS

This study evaluated 52 eyes of 26 consecutive patients with spherical equivalents of -4.19 ± 1.65 diopters (D) (mean ± standard deviation) who underwent FLEx in 1 eye and SMILE in the other eye by randomized assignment. Before surgery, and 1 week and 1, 3, and 6 months after surgery, we assessed safety, efficacy, predictability, stability, and adverse events of the 2 surgical techniques.

RESULTS

LogMAR uncorrected and corrected distance visual acuity was, respectively, -0.17 ± 0.10, -0.20 ± 0.07 in the FLEx group and -0.15 ± 0.10, -0.19 ± 0.07 in the SMILE group 6 months postoperatively. In the FLEx and SMILE groups 6 months postoperatively, 96% and 100% of eyes, respectively, were within 0.5 D of the targeted spherical equivalent correction. Changes of -0.02 ± 0.39 D and 0.00 ± 0.30 D occurred in manifest refraction from 1 week to 6 months in the FLEx and SMILE groups, respectively. No clinically significant complications occurred in the FLEx or the SMILE group.

CONCLUSIONS

Both FLEx and SMILE performed well in the correction of myopia throughout the 6-month observation period. FLEx may be essentially equivalent to SMILE in terms of safety, efficacy, predictability, and stability, suggesting that the presence or absence of lifting the flap does not significantly affect these visual and refractive outcomes.

Longitudinal assessment of optical quality and intraocular scattering using the double-pass instrument in normal eyes and eyes with short tear breakup time

Purpose

To assess the longitudinal changes in optical quality including intraocular scattering in normal eyes and eyes with short tear breakup time (TBUT).

Methods

We prospectively examined twenty eyes of 20 healthy subjects, and age-matched twenty eyes of 20 short TBUT subjects. The modulation transfer function (MTF) cutoff frequency, the Strehl ratio, and the objective scattering index (OSI) were quantitatively assessed using an Optical Quality Analysis System. We investigated the changes in these variables measured consecutively at the initial examination, 5, and 10 seconds without blinking. We also compared these variables in eyes with short TBUT with those in normal eyes.

Results

No significant differences in the MTF cutoff frequency, Strehl ratio, or OSI were detected over a 10-second period in normal eyes. These variables also became significantly degraded even over a 5-second period in eyes with short TBUT (p<0.01). We found significant differences in these variables at 5 and 10 seconds (p<0.05), but none immediately after the blink between normal and short TBUT eyes.

Conclusions

Optical quality including intraocular scattering deteriorated significantly with time in eyes with short TBUT, whereas we found significant differences over a 10-second period in normal eyes. Eyes with short TBUT showed greater deterioration in optical quality after the blink than normal eyes. The longitudinal assessment of optical quality may be effective in distinguishing eyes with short TBUT from normal eyes.

Scleral buckling and pars plana vitrectomy for rhegmatogenous retinal detachment: an analysis of 542 eyes

PURPOSE

To investigate the anatomical success rates of scleral buckling (SB) and pars plana vitrectomy (PPV) performed for rhegmatogenous retinal detachment (RRD) in a large case series and to identify prognostic factors for the primary anatomical success rates of surgical techniques.

METHODS

We reviewed 542 consecutive eyes for primary RRD in this retrospective study. Follow-ups were performed for at least six months. In each of the two groups, 271 eyes were examined. The main outcome measure was the primary anatomical success rate. Multivariate analysis was also performed to determine whether independent risk factors of the preoperative parameters for redetachment exist.

RESULTS

The primary anatomical success rates were 93.7% and 96.3% in the SB and PPV groups; and the final anatomical success rates were 100% in both groups (each with 271 eyes). In the SB group, eyes with macula-off had significantly lower primary anatomical success rates than those with macula-on (p = 0.002). Preoperative break location or lens status had no significant effect on primary anatomical success rates in either group. Multivariate logistic regression analysis using four variables, namely, sex, posterior vitreous detachment, macular status and preoperative visual acuity, showed that the macular status was an independent risk factor for redetachment in the SB group (p = 0.039, odds ratio 3.7). The six-month follow-up visual acuity was significantly better than the preoperative visual acuity in both groups (p ≤ 0.001).

CONCLUSIONS

Both SB and PPV gave excellent primary and final anatomical success rates. The macula-off status was associated with a lower success rate in the SB group, although break location and lens status had no significant effect on success rates in either group.

Effect of fermented bilberry extracts on visual outcomes in eyes with myopia: a prospective, randomized, placebo-controlled study

PURPOSE

To investigate clinically the effects of yeast-fermented bilberry extract on visual outcomes in myopic eyes.

METHODS

In a prospective, randomized, placebo-controlled, cross-over study, we examined 30 eyes of 30 middle-aged healthy volunteers (mean age±standard deviation, 39.5±7.2 years) with myopia [manifest spherical equivalent, -2.40±1.88 diopters (D)], who were randomly assigned to 1 of 2 oral regimens: fermented bilberry extract (400 mg/day) or placebo. We quantitatively assessed visual acuity, refraction, pupil constriction rate, accommodation, and mesopic contrast sensitivity (CS), before and 1 month after treatment. Only the right eyes were tested. The amplitude of accommodation and CS were measured with an accommodometer (D'ACOMO; WOC) and a CS unit (VCTS-6500; Vistech), respectively. From the CS, the area under the log contrast sensitivity function (AULCSF) was calculated.

RESULTS

The mean amplitude of accommodation increased significantly, from 4.62±1.88 D before treatment, to 5.33±2.03 D after treatment in the study group (Wilcoxon signed-rank test, P=0.002). Moreover, the mesopic AULCSF was significantly increased, from 1.04±0.16 before, to 1.13±0.17 after, treatment (P=0.009). However, we found no significant changes in accommodation or AULCSF in the control group (P>0.05), or any significant changes in any other parameters in either group (P>0.05).

CONCLUSIONS

The present data show that fermented bilberry extract is effective in causing increases in subjective accommodation and in mesopic CS in myopic eyes.

Clinical evaluation of the additive effect of diquafosol tetrasodium on sodium hyaluronate monotherapy in patients with dry eye syndrome: a prospective, randomized, multicenter study

PURPOSE

To assess the additive effect of diquafosol tetrasodium on sodium hyaluronate monotherapy in patients with dry eye syndrome.

METHODS

This study evaluated 64 eyes of 32 patients (age: 62.6±12.8 years (mean±SD)) in whom treatment with 0.1% sodium hyaluronate was insufficiently responsive. The eyes were randomly assigned to one of the two regimens in each patient: topical administration of sodium hyaluronate and diquafosol tetrasodium in one eye, and that of sodium hyaluronate in the other. Before treatment, and 2 and 4 weeks after treatment, we determined tear volume, tear film break-up time (BUT), fluorescein and rose bengal vital staining scores, subjective symptoms, and adverse events.

RESULTS

We found a significant improvement in BUT (P=0.049, Dunnett test), fluorescein and rose bengal staining scores (P=0.02), and in subjective symptoms (P=0.004 for dry eye sensation, P=0.02 for pain, and P=0.02 for foreign body sensation) 4 weeks after treatment in the diquafosol eyes. On the other hand, we found no significant change in these parameters after treatment in the control eyes.

CONCLUSIONS

In dry eyes, where sodium hyaluronate monotherapy was insufficient, diquafosol tetrasodium was effective in improving objective and subjective symptoms, suggesting its viability as an option for the additive treatment of such eyes.

Clinical evaluation of the additive effect of diquafosol tetrasodium on sodium hyaluronate monotherapy in patients with dry eye syndrome: a prospective, randomized, multicenter study

PURPOSE

To assess the additive effect of diquafosol tetrasodium on sodium hyaluronate monotherapy in patients with dry eye syndrome.

METHODS

This study evaluated 64 eyes of 32 patients (age: 62.6±12.8 years (mean±SD)) in whom treatment with 0.1% sodium hyaluronate was insufficiently responsive. The eyes were randomly assigned to one of the two regimens in each patient: topical administration of sodium hyaluronate and diquafosol tetrasodium in one eye, and that of sodium hyaluronate in the other. Before treatment, and 2 and 4 weeks after treatment, we determined tear volume, tear film break-up time (BUT), fluorescein and rose bengal vital staining scores, subjective symptoms, and adverse events.

RESULTS

We found a significant improvement in BUT (P=0.049, Dunnett test), fluorescein and rose bengal staining scores (P=0.02), and in subjective symptoms (P=0.004 for dry eye sensation, P=0.02 for pain, and P=0.02 for foreign body sensation) 4 weeks after treatment in the diquafosol eyes. On the other hand, we found no significant change in these parameters after treatment in the control eyes.

CONCLUSIONS

In dry eyes, where sodium hyaluronate monotherapy was insufficient, diquafosol tetrasodium was effective in improving objective and subjective symptoms, suggesting its viability as an option for the additive treatment of such eyes.

Clinical evaluation of optical quality and intraocular scattering after posterior chamber phakic intraocular lens implantation

PURPOSE

We assessed the optical quality and intraocular scattering after posterior chamber phakic intraocular lens implantation.

METHODS

We examined prospectively 38 eyes of 19 consecutive patients undergoing implantable contact lens (ICL) implantation (mean age ± SD 36.3 ± 5.7 years), and 38 age-matched normal eyes of 19 healthy volunteers (mean age 36.4 ± 4.9 years). We assessed quantitatively the values of modulation transfer function (MTF) cutoff frequency, Strehl ratio, objective scattering index (OSI), and the Optical Quality Analysis System (OQAS) values (OVs). We compared these variables in eyes undergoing ICL implantation to those in healthy eyes.

RESULTS

The mean MTF cutoff frequency, Strehl ratio, OSI, OV 100%, OV 20%, and OV 9% were 28.69 ± 8.59 cycles/degree, 0.17 ± 0.04, 1.06 ± 0.48, 0.96 ± 0.29, 0.83 ± 0.31, and 0.83 ± 0.32, respectively, 3 months after ICL implantation. We found no significant differences in the MTF cutoff frequency (Mann Whitney U test, P = 0.31), Strehl ratio (P = 0.46), OSI (P = 0.30), or OVs at contrasts of 100% (P = 0.51), 20% (P = 0.46), and 9% (P = 0.36), between the ICL and control groups.

CONCLUSIONS

The optical quality parameters, such as the MTF cutoff frequency, Strehl ratio, OSI, or OVs in the ICL group, were not significantly different from those in the control group, suggesting that the optical quality and intraocular scattering of eyes undergoing ICL implantation essentially was equivalent to those of healthy eyes.

Effect of aging on optical quality and intraocular scattering using the double-pass instrument

PURPOSE

To assess the effect of aging on optical quality in a normal population.

METHODS

We prospectively examined 100 normal eyes of 100 healthy volunteers (50 men, 50 women; ages, 20-69 years; mean age ± standard deviation, 44.6 ± 15.5 years). We quantitatively assessed the values of MTF cutoff frequency, Strehl ratio, and objective scattering index (OSI), using an Optical Quality Analysis System™ (Visiometrics, Terrassa, Spain). We took these measurements three times each, and the mean value obtained was used for statistical analysis. We investigated the relationships between subject age and these optical quality parameters.

RESULTS

The mean MTF cutoff frequency, Strehl ratio, and OSI, were 27.76 ± 8.41, 0.17 ± 0.05, and 1.29 ± 0.76 cycles/degree, respectively. We found a significant negative correlation between subject age and MTF cutoff frequency (Pearson's correlation coefficient r = -0.606, p < 0.001), and between age and Strehl ratio (r = -0.649, p < 0.001). We also found a significant positive correlation between subject age and OSI (r = 0.691, p < 0.001).

CONCLUSIONS

The MTF cutoff frequency and the Strehl ratio are significantly decreased, and the OSI is significantly increased, by aging, indicating that the optical quality of the eye is degraded in older subjects.