Functional complaints, visual acuity, spatial contrast sensitivity, and glare disability in preoperative and postoperative cataract patients

Impact of Cataract Surgery on Low Luminance Visual Acuity Deficit Measurements

Purpose

The impact of cataract surgery on low luminance visual acuity deficit (LLVAD) measurements was investigated by measuring the LLVAD before and after cataract surgery.

Design

Prospective, longitudinal study.

Participants

Patients undergoing cataract surgery.

Methods

Photopic luminance (PL)–best-corrected visual acuity (BCVA) and low luminance (LL)–BCVA were obtained using the ETDRS chart. Low luminance visual acuity deficit scores were calculated by subtracting the LL-BCVA letter score from the PL-BCVA letter score. To demonstrate the reproducibility of these visual acuity measurements, we used data from drusen-only eyes previously published in the Complement Inhibition with Eculizumab for the Treatment of Nonexudative Age-Related Macular Degeneration (COMPLETE) study. The PL-BCVA, LL-BCVA, and LLVAD measurements obtained at an interval of 3 months in this cohort were used for comparison. In the current study, the impact of cataract surgery on LLVAD measurements was analyzed by comparing the PL-BCVA, LL-BCVA, and LLVAD measurements before and after cataract surgery.

Main Outcome Measures

The reproducibility of the visual acuity measurements and the changes in LLVAD measurement after cataract surgery.

Results

In the COMPLETE study, no clinically significant differences were found in the PL-BCVA, LL-BCVA, or LLVAD measurements between baseline and the 3-month follow-up visits with a change of –1.1 letters, –1.3 letters, and 0.1 letters, respectively (P = 0.02, P = 0.11, and P = 0.88, respectively). In the current study, significant increases were found in the PL-BCVA and LL-BCVA measurements, with a change of 7.3 letters and 10.2 letters after cataract surgery (P < 0.001 for both), and a statistically significant decrease in LLVAD measurements was found, with a change of –3.0 letters after cataract surgery (P = 0.002).

Conclusions

Because of the variable effect of cataracts on LL-BCVA measurements and the significant change in LLVAD measurements after cataract surgery, investigators should be aware that cataract surgery during a trial will have an unpredictable impact on LLVAD measurements, and pseudophakic and phakic patients should be analyzed separately.

Active Learning to Characterize the Full Contrast Sensitivity Function in Cataracts

Background

To characterize contrast sensitivity function (CSF) in cataractous and pseudophakic eyes compared to healthy control eyes using a novel quantitative CSF test with active learning algorithms.

Methods

This is a prospective observational study at an academic medical center. CSF was measured in eyes with visually significant cataract, at least 2+ nuclear sclerosis (NS) and visual acuity (VA) ≥ 20/50, in pseudophakic eyes and in healthy controls with no more than 1+ NS and no visual complaints, using the Manifold Contrast Vision Meter. Outcomes included Area under the Log CSF (AULCSF) and CS thresholds at 1, 1.5, 3, 6, 12, and 18 cycles per degree (cpd). A subgroup analysis as performed on cataract eyes with VA ≥ 20/25.

Results

A total of 167 eyes were included, 58 eyes in the cataract group, 77 controls, and 32 pseudophakic eyes with respective median AULCSF of 1.053 (0.352) vs 1.228 (0.318) vs 1.256 (0.360). In our multivariate regression model, cataract was associated with significantly reduced AULCSF (P= 0.04, β= −0.11) and contrast threshold at 6 cpd (P= 0.01, β= −0.16) compared to controls. Contrast threshold at 6 cpd was significantly reduced even in the subgroup of cataractous eyes with VA ≥ 20/25 (P=0.02, β=−0.16).

Conclusion

The novel qCSF test detected disproportionate significant contrast deficits at 6 cpd in cataract eyes; this remained significant even in the cataractous eyes with VA ≥ 20/25. CSF testing may enhance cataract evaluation and surgical decision-making, particularly in patients with subjective visual complaints despite good VA.

Factors Influencing Contrast Sensitivity Function in Eyes with Mild Cataract

This study was aimed to evaluate the relationship between the area under the log contrast sensitivity function (AULCSF) and several optical factors in eyes suffering mild cataract. We enrolled 71 eyes of 71 patients (mean age, 71.4 ± 10.7 (standard deviation) years) with cataract formation who were under surgical consultation. We determined the area under the log contrast sensitivity function (AULCSF) using a contrast sensitivity unit (VCTS-6500, Vistech). We utilized single and multiple regression analyses to investigate the relevant factors in such eyes. The mean AULSCF was 1.06 ± 0.16 (0.62 to 1.38). Explanatory variables relevant to the AULCSF were, in order of influence, logMAR best spectacle-corrected visual acuity (BSCVA) (p < 0.001, partial regression coefficient B = −0.372), and log(s) (p = 0.023, B = −0.032) (adjusted R² = 0.402). We found no significant association with other variables such as age, gender, uncorrected visual acuity, nuclear sclerosis grade, or ocular HOAs. Eyes with better BSCVA and lower log(s) are more susceptible to show higher AULCSF, even in mild cataract subjects. It is indicated that both visual acuity and intraocular forward scattering play a role in the CS function in such eyes.

Characteristics of corneal high-order aberrations in adolescents with mild to moderate myopia

Background

This study investigated the characteristics of corneal higher-order aberrations (HOAs) of the anterior surface, posterior surface, and total cornea in adolescents with mild to moderate myopia.

Methods

A total of 183 patients with myopia (183 eyes) aged 8 to 18 years were enrolled in this study. The axial length (AL) of the eyes was measured by an IOL-Master, and corneal curvatures (K-values) and HOAs were measured by a Pentacam anterior segment diagnostic analyzer.

Results

Results of this study showed that the anterior, posterior and total corneal horizontal coma Z₃¹ were − 0.1249 ± 0.105 μm, 0.0009 ± 0.001 μm, and − 0.1331 ± 0.116 μm, respectively; the anterior, posterior and total corneal vertical coma Z₃^− 1 were − 0.0212 ± 0.164 μm, 0.0003 ± 0.043 μm, and − 0.0216 ± 0.168 μm, respectively; and spherical aberration (SA) Z₄⁰ values were 0.2244 ± 0.091 μm, 0.1437 ± 0.029 um, and 0.1889 ± 0.090 μm, respectively. Total corneal Z₃¹ was statistically correlated with posterior corneal astigmatism (K₂b − K₁b) (p = 0.038). Total corneal Z₃^− 1 was correlated with anterior corneal astigmatism (K₂f − K₁f) (p = 0.027). Anterior, posterior, and total corneal Z₄⁰ were correlated with anterior and posterior corneal curvature (K₁f, K₂f, K₁b, K₂b) (p = 0.001). Posterior corneal Z₄⁰b was also significantly correlated with AL.

Conclusions

In adolescents with mild to moderate myopia, the posterior corneal surface shape may play a compensatory role in the balance of corneal aberrations, and the posterior corneal SA tended to become less negative as the AL increased. The corneal coma may also play a compensatory role in posterior corneal surface astigmatism, which was valuable for the treatment for improving visual quality. This conclusion still needs to be verified.

Assessment of Vitreous Structure and Visual Function after Neodymium:Yttrium-Aluminum-Garnet Laser Vitreolysis

PURPOSE

Neodymium:yttrium-aluminum-garnet (Nd:YAG) laser treatment is performed on vitreous floaters, but studies of structural and functional effects with objective outcome measures are lacking. This study evaluated Nd:YAG laser effects by comparing participants with vitreous floaters who previously underwent laser treatment with untreated control participants and healthy persons without vitreous floaters using quantitative ultrasonography to evaluate vitreous structure and by measuring visual acuity and contrast sensitivity function to assess vision.

DESIGN

Retrospective, comparative study.

PARTICIPANTS

One eye was enrolled for each of 132 participants: 35 control participants without vitreous floaters, 59 participants with untreated vitreous floaters, and 38 participants with vitreous floaters previously Nd:YAG-treated. Of these, 25 were dissatisfied and sought vitrectomy; 13 were satisfied with observation.

METHODS

The 39-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-39) to assess participant visual well-being, quantitative ultrasonography (QUS) to measure vitreous echodensity, and best-corrected visual acuity (BCVA) and contrast sensitivity function (CSF) to evaluate vision.

MAIN OUTCOME MEASURES

Results of NEI-VFQ-39, QUS, BCVA, and CSF.

RESULTS

Compared with control participants without vitreous floaters, participants with untreated vitreous floaters showed worse NEI-VFQ-39 results, 57% greater vitreous echodensity, and significant (130%) CSF degradation (P < 0.001 for each). Compared with untreated eyes with vitreous floaters, Nd:YAG-treated eyes had 23% less vitreous echodensity (P < 0.001), but no differences in NEI-VFQ-39 (P = 0.51), BCVA (P = 0.42), and CSF (P = 0.17) results. Of 38 participants with vitreous floaters who previously were treated with Nd:YAG, 25 were dissatisfied and seeking vitrectomy, whereas 13 were satisfied with observation. Participants seeking vitrectomy showed 24% greater vitreous echodensity (P = 0.018) and 52% worse CSF (P = 0.006). Multivariate linear regression models confirmed these findings.

CONCLUSIONS

As a group, participants previously treated with Nd:YAG laser for bothersome vitreous floaters showed less dense vitreous, but similar visual function as untreated control participants with vitreous floaters. Because some treated eyes showed less dense vitreous and better visual function than those of untreated control participants, a prospective randomized study of Nd:YAG laser treatment of vitreous is warranted, using uniform laser treatment parameters and objective quantitative outcome measures.

Changes of Visual Function and Visual Ability in Daily Life Following Cataract Surgery

Purpose: To examine best corrected visual acuity (BCVA), contrast sensitivity (CS) and functional visual complaints in early cataract and after the cataract surgery. Patients and methods: 53 eyes with early cataract (BCVA 20/30: Snellen charts) were examined before the surgery as well as 12 months after the surgery. BCVA was tested using logMAR chart. CS was examined using VCTS chart in 6 spatial frequencies. Influence of glare was tested using BAT. Patients’ subjective visual functions were evaluted using a questionnaire (distance vision, near vision, mesopic vision and glare conditions). 22 subjects were examined as control group. Results: BCVA was 0.52 (0.22–1.05) preoperatively and 0.83 (0.37–1.26) postoperatively. BCVA in patients in both terms was significantly lower compared to the control group. CS in patients before surgery was significantly lower compared to controls, postoperatively improved significantly and was only nonsignificantly lower compared to controls except for the highest spatial frequency. Glare had only nonsignificant influence. The questionnaire scores were correlated with visual performance in both terms. Conclusions: The significant improvement of both BCVA and CS suggest that cataract surgery improves quality of life in early cataract. Questionnaire should be considered as adjuncts to BCVA and CS in evaluating early cataract.

Comparison of Ocular Aberrations in Two Hydrophobic and Hydrophilic Intraocular Lenses

OBJECTIVE

To compare differences in higher-order aberrations (HOAs) between two standard spherical monofocal intraocular lenses (IOLs), the hydrophobic acrylic Alcon SA60AT (Bausch & Lomb), and hydrophilic acrylic Rayner Superflex (620H) (Rayner).

METHODS

In this case series, sixty-eight eyes of 68 patients who underwent phacoemulsification cataract surgery were studied. In group 1 (n=39), the hydrophobic Alcon SA60AT IOL, and in group 2 (n=29), the hydrophilic Rayner Superflex (620H) IOL, were implanted. Distant best-corrected visual acuity was 20/20. Aberrometry was performed by the OPD Scan III (Nidek) on the undilated pupil and under mesopic conditions at the first and third months after surgery.

RESULTS

There were no differences between the two groups in the mean total coma, total trefoil, total spherical aberration, and total HOAs in the two follow-up sessions (P>0.5, Independent t test). According to the repeated measure analysis of variance test results, total coma, total trefoil, total spherical aberration, and total HOAs significantly increased over time (P=0.033, P=0.017, P=0.005, P=0.004, respectively), although these changes were not significant between the two groups.

CONCLUSION

It seems that IOL optically behaves differently in vivo versus in vitro conditions and environmental factors can affect the increase or decrease in HOAs by an IOL. Therefore, we should consider these factors and the effect of IOL material and design. Also, the implantation of the Alcon SA60AT and Rayner Superflex IOL does not induce higher HOAs in pseudophakic versus phakic eyes.

Evaluation of contrast sensitivity measurements after retrobulbar optic neuritis in Multiple Sclerosis

Background

The evaluation of contrast sensitivity is an important additional examination that allows the physician to achieve the full picture of a patient's quality of vision. In low-contrast conditions, more discrete visual dysfunctions may be revealed, which could be overlooked in high-contrast tests.

Methods

The examined group consisted of 33 eyes of 27 patients with multiple sclerosis. The study included patients with full or almost full visual acuity, without visual field defects or any other ophthalmic condition, and who had never undergone any ocular surgery or trauma. The reference group consisted of 49 eyes of 37 patients. This group included healthy subjects with full visual acuity. Contrast sensitivity was examined with a Functional Vision Analyzer™ device in photopic conditions (with and without glare) and in mesopic conditions (with and without glare).

Results

In patients with multiple sclerosis who had experienced optic neuritis, contrast sensitivity was found to be significantly reduced in all spatial frequencies in both mesopic and photopic conditions (with and without glare).

Conclusions

Contrast sensitivity in patients with multiple sclerosis who have also had optic neuritis is significantly reduced. This may explain patients' complaints regarding their quality of vision, despite good visual acuity. Contrastometry is a useful basis for further examination, providing additional information regarding a patient's quality of vision.

Functional improvement after one- and two-eye cataract surgery in the Salisbury Eye Evaluation

PURPOSE

To determine the impact that cataract and cataract surgery have on clinical measurements of vision, reading speed, objective mobility performance, and subjective visual functioning.

DESIGN

Prospective, population-based study.

PARTICIPANTS

A total of 1739 Salisbury Eye Evaluation (SEE) participants without previous cataract surgery with bilateral baseline best-corrected visual acuity (BCVA) of logarithm of the minimum angle of resolution (logMAR) ≤ 0.3 (≥ 20/40) or cataract surgery between rounds 1 and 2.

METHODS

Participants were categorized on the basis of cataract surgery by round 2 into no surgery, unilateral surgery, or bilateral surgery. Visual performance, mobility-based tasks, and the Activities of Daily Vision Scale (ADVS) were measured at baseline and 2 years. Mobility score was converted into a z score by subtracting the participant's time from the population baseline average and then dividing by the standard deviation. Comparisons were made between the no surgery and surgery groups using multivariate linear regression.

MAIN OUTCOME MEASURES

Change in bilateral BCVA in logMAR, contrast sensitivity, reading speed in words per minute (wpm), mobility score, and ADVS.

RESULTS

During the study period, 29 participants had cataract surgery on both eyes, 90 participants had unilateral surgery, and 1620 participants had no surgery. After adjusting for baseline value, demographics, depression, and mental status, the unilateral surgery group's BCVA improved 0.04 logMAR (P = 0.001) and the bilateral group's BCVA improved 0.13 compared with no surgery (P<0.001). Overall mobility declined in all groups. The unilateral group's z score decreased 0.18 more than that of the no surgery group (P = 0.02), whereas the bilateral group showed a 0.18 z score improvement compared with no surgery (P = 0.19). Change in reading speed significantly improved in the unilateral and bilateral groups compared with no surgery (12 and 31 wpm, respectively). The bilateral surgery group showed significant positive change in ADVS compared with no surgery (5 points of relative improvement; P = 0.01), whereas the unilateral group showed a 5-point relative decline (P<0.001).

CONCLUSIONS

Cataract negatively affects both subjective quality of life and objective performance measures. Unilateral cataract surgery improves visual functioning, but the largest gains are found in patients who undergo second-eye cataract surgery. This finding supports second-eye cataract surgery for patients with visual or functional symptoms even after successful first-eye surgery.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Objective assessment of crystalline lens opacity level by measuring ocular light scattering with a double-pass system

PURPOSE

To assess the crystalline lens opacity level by measuring ocular light scattering with a double-pass system.

DESIGN

Prospective, single-center, cross-sectional study.

METHODS

Two hundred fifty-three eyes of 135 patients referred for cataract evaluation were enrolled. Patients with corneal or retinal anomalies potentially impairing ocular transparency were excluded. Lens opacification was assessed by the Lens opacities classification system III. Optical Quality Analysis System (Visiometrics SL) measurements provided ocular Modulation Transfer Function cutoff frequency and Objective Scatter Index. Best-corrected visual acuity and Quality of Vision questionnaire scores (Rasch-scaled) were recorded. We analyzed correlations between visual acuity, type and severity of cataract, Optical Quality Analysis System measurements, and discomfort level in each group.

RESULTS

In patients with best-corrected visual acuity better than 20/32, we found correlations between Objective Scatter Index, Modulation Transfer Function, and visual acuity (r = 0.4, P < .0001). The Objective Scatter Index, Modulation Transfer Function, and visual acuity were correlated with each type of cataract. In patients with good visual acuity and moderate functional symptoms, the Objective Scatter Index values also were correlated to the severity of posterior subcapsular cataract (r = 0.4, P = .0006).

CONCLUSIONS

Patients with incipient cataract may report visual discomfort, despite minor lens opacity on slit-lamp examination, minor loss of best-corrected visual acuity, or both. The measurement of ocular scattering with the Optical Quality Analysis System device may be a useful tool in the preoperative evaluation of patients with early cataract.

Contour enhancement benefits older adults with simulated central field loss

PURPOSE

Age-related macular degeneration is the leading cause of vision loss among Americans aged >65 years. Currently, no effective treatment can reverse the central vision loss associated with most age-related macular degeneration. Digital image-processing techniques have been developed to improve image visibility for peripheral vision; however, both the selection and efficacy of such methods are limited. Progress has been difficult for two reasons: the exact nature of image enhancement that might benefit peripheral vision is not well understood, and efficient methods for testing such techniques have been elusive. The current study aims to develop both an effective image enhancement technique for peripheral vision and an efficient means for validating the technique.

METHODS

We used a novel contour-detection algorithm to locate shape-defining edges in images based on natural-image statistics. We then enhanced the scene by locally boosting the luminance contrast along such contours. Using a gaze-contingent display, we simulated central visual field loss in normally sighted young (aged 18-30 years) and older adults (aged 58-88 years). Visual search performance was measured as a function of contour enhancement strength ["original" (unenhanced), "medium," and "high"]. For preference task, a separate group of subjects judged which image in a pair "would lead to better search performance."

RESULTS

We found that although contour enhancement had no significant effect on search time and accuracy in young adults, Medium enhancement resulted in significantly shorter search time in older adults (about 13% reduction relative to original). Both age-groups preferred images with Medium enhancement over original (2-7 times). Furthermore, across age-groups, image content types, and enhancement strengths, there was a robust correlation between preference and performance.

CONCLUSIONS

Our findings demonstrate a beneficial role of contour enhancement in peripheral vision for older adults. Our findings further suggest that task-specific preference judgments can be an efficient surrogate for performance testing.

The impact of cataract surgery on quality of life

PURPOSE OF REVIEW

This review summarizes the recent literature of the impact of cataract surgery from the patient's perspective, with a focus on second-generation patient reported outcome (PRO) measures that used Rasch analysis to explore their data.

RECENT FINDINGS

Irrespective of the instrument utilized, the overriding conclusion is that cataract surgery unequivocally improves vision-specific functioning and several aspects of vision-specific quality of life. The benefit of cataract surgery, however, on generic health is less clear, due to limited vision-related items. Evidence suggests that cataract surgery also improves visual functioning in comorbid eye disease, especially in the early stages. Similarly, second eye cataract surgery appears to improve visual ability beyond that achieved with first eye surgery. Recently, there has been a shift toward second-generation, Rasch-validated PROs to assess cataract surgery outcomes and large gains in visual function have been demonstrated. Importantly, measurement precision is dramatically improved compared with the original first-generation instruments.

SUMMARY

Cataract surgery-induced improvements in visual acuity are translated by considerable gains in real life activities, emotional and social life components. The utilization of second-generation instruments and modern psychometric methods, however, appears to be the best current strategy to optimize the impact of cataract surgery on health-related quality of life.

Effects on vision with glare after correction of monochromatic wavefront aberrations

PURPOSE

To investigate effects of optical aberration correction on vision with glare.

METHODS

Correction of aberrations up to the 6th Zernike order (closed-loop correction) was compared with conventional spectacle correction in 42 healthy eyes. To create these corrections, an adaptive optics system including a thin-film transistor (TFT) monitor for displaying optotypes with additional glare sources was used. Employing both corrections, visual acuity and contrast sensitivity (CS) were tested alternately with and without glare. Disability glare was computed as the difference between log CS without and with glare. Individuals were also asked to rate subjectively the quality of three images displayed on the TFT monitor.

RESULTS

Significant improvements of CS without and with glare were found with the closed-loop correction (0.147 and 0.198 log CS, respectively), whereas no significant difference in visual acuity was found in either correction. Correlations were determined between reduction of total root-mean-square error and increase of CS with glare (Pearson correlation coefficient r=0.42) and decrease of disability glare (r=-0.33). Visual acuity was correlated with the visual Strehl ratio based on the optical transfer function (r=0.46). Subjective comparison of the images showed improvements more clearly. Depending on the image, in 57% to 78% of the eyes, closed-loop correction was rated better than spectacle correction. The subjective glare effect was reduced as well.

CONCLUSIONS

Investigation of vision with glare seems to be a reasonable additional test to evaluate the visual outcome of a customized correction.

Psychophysical impact and optical and morphological characteristics of symptomatic non-advanced cataract

PURPOSE

To investigate whether psychophysical, morphological, and/or optical characteristics of symptomatic non-advanced cataract are complementary to, or more appropriate than, visual acuity (VA) for the purposes of recording visual data that reflect subjective visual difficulty in patients with cataract that exhibit relative sparing of high contrast acuity (0.4 logarithm of minimal angle of resolution (logMAR) scale or better).

METHODS

Eighty-two patients with symptomatic non-advanced cataract and no other ocular pathology were asked to complete a validated questionnaire, and to perform a series of visual function assessments including: corrected distance VA (CDVA); photopic and mesopic contrast sensitivity; photopic and mesopic glare disability (GD); reading acuity and reading speed; stereoacuity; and retinal sensitivity. Optical and morphological characteristics of the cataract were evaluated by lens optical density and by the Lens Opacities Classification System III, respectively. Correlations between questionnaire score and each of these measures were calculated.

RESULTS

Statistically significant negative correlations were observed between the Rasch-scaled questionnaire score and mesopic GD (at 3 and 6 cycles per degree (cpd); r=-0.396 (P<0.01) and -0.451 (P<0.05), respectively) and between the Rasch-scaled questionnaire score and photopic GD (at 3 and 6 cpd; r=-0.328 (P<0.01) and -0.440 (P<0.01), respectively).

CONCLUSION

Symptomatic non-advanced cataract, in the presence of good CDVA, is associated with measurable subjective visual difficulty, best reflected in a decrease in mesopic and photopic GD (at medium spatial frequencies). CDVA does not reflect the patient's visual dissatisfaction in such cases.

Development and validation of clinical scores for visual outcomes after cataract surgery

PURPOSE

To develop and validate a clinical score to predict visual acuity (VA) and functional changes after phacoemulsification on the basis of readily obtainable preoperative history data and patient assessment.

DESIGN

Prospective follow-up study.

PARTICIPANTS

A sample of 5512 patients on waiting lists for phacoemulsification at 17 hospitals in Spain.

METHODS

Data were obtained at the baseline examination from the 5512 patients. The patients were divided randomly into 2 subgroups: derivation (n = 3285; 60%) and validation (n = 2227; 40%). The preoperative predictors of postoperative gains in VA and visual function index 14 (VF-14) were determined by multivariate logistic regression analysis and implemented using a prediction score.

MAIN OUTCOME MEASURES

Probability of postoperative improvement in VA and VF-14 scores. The cutoff points were established for each outcome on the basis of the minimal clinically important difference values.

RESULTS

The predictive variables for VA gain were the baseline VA, patient age, ocular comorbidity, and surgical complexity. Regarding the VF-14, the predictive factors were the preoperative VF-14, the eye with the better VA, and the surgical complexity. In the multivariate logistic model in the derivation sample, the final VA and VF-14 scores ranged from 0 to 44 and from 0 and 24, respectively. Receiver operating characteristic curves were developed in the derivation and validation samples, and no statistical significance was found when their areas under the curve were compared. Areas under the curve ranged from 65% to 80%. Both scores had a positive predictive value from 74% to 85%.

CONCLUSIONS

Newly developed and validated clinical prediction scores may assist physicians and patients in decision making about the expected outcomes and benefits of cataract surgery.

Effects of spherical aberration on visual acuity at different contrasts

PURPOSE

To evaluate the effect of spherical aberration on visual acuity by correcting and inducing spherical aberration using an adaptive optics vision simulator.

SETTING

Laboratory of Vision Science, Capital Medical University, Beijing, and Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, China.

METHODS

An adaptive optics vision simulator comprising a wavefront sensor and a 37-segmented deformable mirror was used to correct and induce aberrations of the eye. The effective ocular wavefront aberration was manipulated with the deformable mirror, as the resulting visual performance was simultaneously measured. Subjective visual acuity measurements were performed with a 6.0 mm pupil. Visual acuity at different contrasts was measured when spherical aberration was fully corrected and the other natural aberrations in the eye were present and when spherical aberration values were induced with the other aberrations corrected.

RESULTS

The natural root-mean-square (RMS) value of spherical aberration in the 8 subjects examined was between -0.11 microm and 0.14 microm. There was no significant improvement in visual acuity with spherical aberration corrected and the subjects' natural aberrations present. When all aberrations were corrected, a decrease in visual acuity occurred when spherical aberration RMS was induced at 0.2 microm and 0.3 microm.

CONCLUSIONS

When fluctuation of other natural aberrations in the eye were present, there was a slight effect on visual acuity when the spherical aberration RMS was approximately 0.1 microm. Therefore, an RMS value of 0.1 microm could be an acceptable amount of spherical aberration when correcting spherical aberrations.

The effects of posterior continuous curvilinear capsulorhexis on contrast sensitivity

PURPOSE

We aimed at evaluating the effects of posterior continuous curvilinear capsulorhexis (PCCC) on contrast sensitivity.

MATERIALS AND METHODS

In this prospective, randomized, bilateral clinical study, 40 eyes of 20 patients who underwent bilateral cataract surgery were included. The phacoemulsification machine, viscoelastic substances, surgical tools, and intraocular lenses (IOLs) were the same for both eyes. The only difference was that we conducted the PCCC procedure before IOL implantation to one of the eyes of the patients. The selection of the eye that underwent the PCCC procedure was decided randomly.

RESULTS

The mean photopic contrast sensitivity values at spatial frequencies of 1.5, 3, 6, 12, and 18 cpd (cycles per degree) were 41.55, 59.90, 61.25, 32.35, and 9.75, respectively, and for the control group these values were 39.05, 56.60, 57.95, 29.80, and 8.75, respectively. The mean mesopic contrast sensitivity values at special frequencies of 1.5, 3, 6, 12, and 18 cpd were 41.20, 54.75, 55.55, 31.70, and 9.00, respectively, and for the control group these values were 38.35, 51.70, 52.15, 30.05, and 8.00, respectively. The mean contrast sensitivity values of the eyes that underwent the PCCC procedure were slightly better than the fellow eyes at all spatial frequencies, but the difference was statistically insignificant (P>0.05).

CONCLUSIONS

In early post-operative period, the PCCC procedure exerts some positive effects on contrast sensitivity although these effects are statistically insignificant.

Improvement of functional visual acuity after cataract surgery in patients with good pre- and postoperative spectacle-corrected visual acuity

PURPOSE

To report the changes in functional visual acuity in cataract surgery patients with good pre- and postoperative visual acuity.

METHODS

Functional visual acuity was evaluated in 13 eyes of 10 patients before and 1 month after phacoemulsification with implantation of acrylic intraocular lenses. Pre- and postoperative best spectacle-corrected visual acuities (BSCVA) were better than 20/25 in all patients. Low contrast visual acuity and Schirmer tests were also performed before and after surgery.

RESULTS

Mean pre- and postoperative logMAR BSCVA were -0.02 +/- 0.06 and -0.05 +/- 0.04, respectively (P > .05). Mean preoperative logMAR functional visual acuity improved from 0.29 +/- 0.17 to 0.092 +/- 0.13 postoperatively (P < .05). The visual maintenance ratio in functional visual acuity and low contrast visual acuity also improved significantly after cataract surgery (P < .05).

CONCLUSIONS

Measurement of functional visual acuity seems to be useful in the evaluation of timing of surgery, visual quality, and changes in kinetic vision after phacoemulsification surgery.

Quality of vision after cataract surgery after Tecnis Z9000 intraocular lens implantation: effect of contrast sensitivity and wavefront aberration improvements on the quality of daily vision

PURPOSE

To compare ocular performance and quality of vision in pseudophakic eyes with an aspherical intraocular lens (IOL) or a conventional spherical IOL.

SETTING

Bretonneau University Hospital, Tours, France.

METHODS

Twenty patients (40 eyes) were randomly divided in 2 equal groups to bilaterally receive the aspherical Tecnis Z9000 IOL (AMO) or the spherical CeeOn Edge 911 IOL (AMO). Contrast sensitivity was measured and ocular wavefront analysis performed before surgery and 6 months after. Patients completed the Activities of Daily Vision Scale (ADVS) to evaluate patient-centered visual outcomes. Other examinations included refraction before and after mydriasis and pupil diameter.

RESULTS

The mean postoperative best corrected visual acuity (logMAR) was 0.03 +/- 0.05 (SD) in the Tecnis group and 0.01 +/- 0.05 in the CeeOn Edge group (P = .41). Refractive evaluation with mydriasis showed a mean myopic shift as low as -0.02 +/- 0.36 diopter (D) in the Tecnis group and -0.51 +/- 0.37 D in the CeeOn Edge group (P = .001). Mesopic contrast sensitivity at high spatial frequencies was significantly better in the Tecnis group (P<.001), while contrast sensitivity under photopic and glare conditions was not different between the 2 groups. Spherical aberration was significantly lower in the Tecnis group, which had a mean Z(4)(0) of 0.01 +/- 0.06 microm, than in the CeeOn Edge group, which had a mean Z(4)(0) of 0.16 +/- 0.12 microm (P<.001). The global score on the ADVS was not statistically different between groups; however, quality of distance vision was better in the Tecnis group than in the CeeOn Edge group (mean 99.0 +/- 2.0 versus 89.2 +/- 3.4) (P<.001).

CONCLUSION

Implantation of an aspherical IOL with a negative spherical aberration resulted in reduced ocular spherical aberration and improved mesopic contrast sensitivity and led to better subjective quality of vision.

Predictions of postoperative visual outcome in subjects with cataract: a preoperative and postoperative study

AIM

To assess the ability of critical flicker frequency (CFF) and optimal reading speed (ORS) to predict the potential vision in patients with cataract with and without ocular comorbidity.

METHODS

The two novel tests were compared with two well established potential vision tests (PVTs), the potential acuity meter (PAM) and the laser interferometer (LI). Measurements were made preoperatively in 1 eye of 88 subjects using the battery of 4 PVTs. Postoperative measurements were made with the CFF and the ORS. The subjects studied were consecutive cases over a 12-month period who fulfilled the inclusion and exclusion criteria, and agreed to participate in this study.

RESULTS

CFF was the PVT most resistant to the presence of cataract. Both CFF and ORS give a similar predictive precision in the presence of cataract and ocular comorbidity, although CFF seems more precise when the cataract is dense.

CONCLUSIONS

The PAM and the LI showed a limited clinical capability in predicting postoperative visual acuity, particularly with dense opacities. The CFF shows the most promise as a PVT, particularly with dense cataract. Further evaluation is required for both CFF and ORS.

Corneal and total wavefront aberrations in phakic and pseudophakic eyes after implantation of monofocal foldable intraocular lenses

PURPOSE

To compare the correlation between corneal and total wavefront aberrations in normal phakic and pseudophakic eyes after implantation of foldable monofocal intraocular lenses (IOLs).

SETTING

University Hospital, Eye Clinic, Zurich, Switzerland.

METHODS

Wavefront aberrations and corneal topography of 29 eyes that had cataract surgery with implantation of hydrophobic monofocal foldable IOL (AcrySof, Alcon Labs) were measured at least 2 months postoperatively and compared with wavefront measurements performed in 33 normal young phakic eyes. The total wavefront aberrations were measured by means of a Tscherning wavefront sensor at a wavelength of 660 nm (Allegro Wave Analyzer, WaveLight Laser Technology). The corneal aberrations were derived from corneal topography measurements ascertained with a Placido-based topography system (Keratograph 70600, Oculus). The correlations between corneal and total wavefront aberrations were calculated for all Zernike coefficients from 2nd up to 6th order.

RESULTS

There was a significant correlation between corneal and total wavefront aberrations in astigmatism C3 and C5 as well as for all 3rd-order Zernike coefficient in both groups (except C8 in the pseudophakic group). The correlation between corneal and total astigmatism (C3 and C5) was higher in the pseudophakic than in the phakic eyes. In contrast, the correlation for the coma-like aberrations was weaker in the pseudophakic eyes (R>0.18) than in the group of phakic eyes (R>0.58). In both groups, there was no significant correlation between spherical aberration C12 of the cornea and the C12 of the total eye.

CONCLUSION

After cataract surgery with an IOL implantation, both vertical and horizontal coma, as well as spherical aberration, were of higher value than in normal eyes. The compensation effect for corneal aberrations of the natural lens is absent in the IOL and explains these findings. The corneal aberrations in pseudophakic eyes reflect better the optical quality of the total eye than the phakic eyes. Nevertheless, the missing correlation in some specific aberrations, such as C8 and C10, shows the inability of corneal topography to provide suitable information on the optical quality of the total eye after cataract surgery. Thus, both corneal and total wavefront measurements are relevant for the assessment of outcomes after cataract surgery.

Contrast sensitivity and disability glare in patients with dry eye

PURPOSE

To evaluate contrast sensitivity and disability glare in patients with dry eye using the Contrast Glaretester 1000.

METHODS

Contrast sensitivity and disability glare were determined in 33 eyes of 33 patients with dry eye and 30 eyes of 30 healthy control subjects for six target sizes with a visual angle of 6.3-0.7 degrees using the Contrast Glaretester 1000, whose working mechanism is similar to that of the conventional perimetry instrument.

RESULTS

Contrast sensitivity was significantly worse in dry eye group when viewing all target sizes (reduction of 0.10-0.25 log contrast units, p < 0.01) except at 6.3 degrees. In the presence of glare, differences in log contrast sensitivity between the groups (0.10-0.25 units) were significant (p < 0.01) for all target sizes, with the dry eye group showing worse results. The reduction in contrast sensitivity induced by glare (disability glare) was significantly worse in the dry eye group versus the control group but only for the 2.5-degree size target, where 0.14 log contrast units were lost.

CONCLUSIONS

Contrast sensitivity with and without glare was significantly reduced in patients with dry eye compared with control subjects, but the number of log contrast units lost with glare (disability glare) was similar in the two groups, except for the 2.5-degree size target.

Effect of cataract surgery with intraocular lens implant on frequency doubling perimetry

PURPOSE

To study the effect of cataract surgery with intraocular lens (IOL) on frequency doubling perimetry (FDP).

METHODS

Patients aged 40 years or above seen at our outpatient clinic with no ocular pathology except for visually significant cataract and visual acuity 6/24 or better were eligible. They underwent FDP before and 4 to 6 weeks after cataract surgery with IOL.

RESULTS

Screening test: Mean scores by three different scoring methods were 1.82 (3.21), 2.80 (5.54), 4.18 (9.18) before and 0.22 (0.51), 0.26 (0.63), 0.26 (0.69) after surgery (p = 0.002 0.001, < 0.0001). Threshold test: Mean deviation (MD) and pattern standard deviation (PSD) were -5.23 (3.08) and 5.15 (2.78) before and -2.94 [corrected] (2.49) (p < 0.0001) and 5.21 (1.780) (p = 0.63) after surgery.

CONCLUSIONS

The screening test should be interpreted cautiously in the presence of cataract. On threshold testing, cataract surgery causes significant decrease in MD but no change in PSD.

The usefulness of Vistech and FACT contrast sensitivity charts for cataract and refractive surgery outcomes research

AIM

To investigate the repeatability and sensitivity of two commonly used sine wave patch charts for contrast sensitivity (CS) measurement in cataract and refractive surgery outcomes.

METHODS

The Vistech CS chart and its descendant, the Functional Acuity Contrast Test (FACT), were administered in three experiments: (1) Post-LASIK and age matched normal subjects; (2) Preoperative cataract surgery and age matched normal subjects; (3) Test-retest repeatability data in normal subjects.

RESULTS

Contrast sensitivity was similar between post-LASIK and control groups and between the Vistech and FACT charts. The percentage of subjects one month post-LASIK achieving the maximum score across spatial frequencies (1.5, 3, 6, 12, 18 cycles per degree) were (50, 33, 13, 13, 0 respectively) for FACT, but only (0, 0, 13, 4, 0 respectively) for Vistech. A small number of cataract patients also registered the maximum score on the FACT, but up to 60% did not achieve the minimum score. Test-retest intraclass correlation coefficients varied from 0.28 to 0.64 for Vistech and 0.18 to 0.45 for FACT. Bland-Altman limits of agreement across spatial frequencies were between +/-0.30 and +/-0.85 logCS for Vistech, and +/-0.30 to +/-0.75 logCS for FACT.

DISCUSSION

The Vistech was confirmed as providing poorly repeatable data. The FACT chart, likely because of a smaller step size, showed slightly better retest agreement. However, the reduced range of scores on the chart due to the smaller step size led to ceiling (post-LASIK) and floor (cataract) effects. These problems could mask subtle differences between groups of patients with near normal visual function as found post-refractive or cataract surgery. The Vistech and FACT CS charts are ill suited for refractive or cataract surgery outcomes research.

Effect of intraocular lens implantation on visual acuity, contrast sensitivity, and depth of focus

PURPOSE

To determine the role of spherical and irregular aberrations in the optics of the natural eye and after intraocular lens (IOL) implantation in terms of visual acuity, contrast sensitivity, and depth of focus.

SETTING

Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands.

METHODS

Visual acuity and defocus-specific contrast sensitivity in 11 pseudophakic patients (IOL group) and 27 age-matched phakic subjects were compared. The results were obtained psychophysically. Spherical and irregular aberrations were subsequently estimated by comparing the measured myopic shift (optimum focus of contrast sensitivity at 4 cycles per degree [cpd] compared to that at 16 cpd) and depth of focus with those of theoretical eye models with varying amounts of irregular and spherical aberrations.

RESULTS

The best corrected visual acuity and best corrected contrast sensitivity in the IOL group did not significantly differ from that in the phakic group. The depth of focus was larger in the IOL group at a pupil diameter of 6.0 mm (P<.05). Comparison with theoretical eye models suggested a higher amount of spherical aberration in the IOL group; irregular aberration was almost the same in both groups.

CONCLUSIONS

There was a higher amount of spherical aberration in the IOL group, related to a larger depth of focus, without loss of contrast sensitivity at optimum focus or loss of visual acuity. This might contribute to better quality of vision in pseudophakic subjects than in presbyopic phakic subjects.

Beyond visual acuity: new and complementary tests of visual function

Visual acuity is an essential component of the routine ophthalmic examination and the most common measure of visual function. There is increasing recognition, however, of the need to evaluate visual function beyond the limited extent afforded by visual acuity. The primary objective of this article is to introduce a variety of new and lesser-used techniques for measuring visual function that complement visual acuity assessment, each of which has been shown to detect visual dysfunction in patients with normal visual acuity.

Cataract surgery and changes in quality of life measures

BACKGROUND

This study examines whether quality of life measured with non-disease specific instruments is altered by cataract surgery and whether the effect is modulated by the presence of ocular comorbidity or other non-ocular issues.

METHODS

Thirteen patients were assessed pre- and at three months post-cataract surgery. Visual disability was measured with the Visual Disability Assessment. Quality of life was measured using two established generic instruments: the Cantril Ladder and the Profile of Mood States (POMS). Subjects were also asked to report any events that may have influenced their quality of life in the three months after surgery.

RESULTS

Visual acuity and visual disability were significantly improved by surgery (p < 0.01). Cantril Ladder score was significantly improved after surgery (p = 0.04). The POMS score improved significantly after surgery, only when cases with ocular comorbidity were excluded (p = 0.04). Two cases had a large deterioration in POMS score that was attributable in one case, to the death of a partner and in the other (a patient with severe glaucoma) to depression from the realisation that there was no further potential for visual improvement.

DISCUSSION

Quality of life can be measurably improved by cataract surgery. However, this is less likely if ocular comorbidity is present. The use of generic instruments for outcome studies increases the likely influence of external factors on quality of life measures. Disease specific instruments, such as the Visual Disability Assessment, should be used wherever possible in outcomes research.

Night vision disturbances after corneal refractive surgery

A certain percentage of patients complain of "glare" at night after undergoing a refractive surgical procedure. When patients speak of glare they are, technically, describing a decrease in quality of vision secondary to glare disability, decreased contrast sensitivity, and image degradations, or more succinctly, "night vision disturbances." The definitions, differences, and methods of measurement of such vision disturbances after refractive surgery are described in our article. In most cases of corneal refractive surgery, there is a significant increase in vision disturbances immediately following the procedure. The majority of patients improve between 6 months to 1 year post-surgery. The relation between pupil size and the optical clear zone are most important in minimizing these disturbances in RK. In PRK and LASIK, pupil size and the ablation diameter size and location are the major factors involved. Treatment options for disabling glare are also discussed. With the exponential increase of patients having refractive surgery, the increase of patients complaining of scotopic or mesopic vision disturbances may become a major public health issue in the near future. Currently, however, there are no gold-standard clinical tests available to measure glare disability, contrast sensitivity, or image degradations. Standardization is essential for objective measurement and follow-up to further our understanding of the effects of these surgeries on the optical system and thus, hopefully, allow for modification of our techniques to decrease or eliminate post-refractive vision disturbances.

Vision-specific instruments for the assessment of health-related quality of life and visual functioning: a literature review

Clinically objective measures such as visual acuity or visual field provide an assessment of a patient's visual status. However such measures may not reflect the degree of visual impairment the patient experiences in his or her daily activities. Visual impairment has been shown to have negative effects on health-related quality of life (HR-QOL) and a significant impact on daily functioning, including social activities. As such, there is a growing recognition of the importance of patient-reported outcomes of visual functioning. This review examines the development and psychometric properties of 22 vision-specific instruments assessing visual functioning and/or the impact of visual impairment on HR-QOL or daily activities. Issues relevant to assessing vision-specific subjective outcomes are reviewed, with specific application of the reviewed instruments. Three instruments, the Activities of Daily Vision Scale, National Eye Institute Visual Function Questionnaire, and Visual Function Index have been well validated and widely used, but others also show promise. To fully capture the benefits of a new ophthalmology treatment (or new treatment for eye disease) a valid and reliable visual instrument, in which the psychometric performance has been demonstrated in the particular ocular condition being treated, should be utilised.

Indications for cataract surgery

This review article will attempt to guide ophthalmologists in deciding the indications for cataract surgery. It will consider this year's visual function questionnaires, ancillary vision tests, and postoperative outcome measures to assess visual function. Cultural factors, age, and gender are a few of the confounding variables in trying to assess visual function. The indications for cataract surgery in the 21st century have evolved dramatically since cataract surgery was first performed in the 1700s. The physicians' dictum in the Hippocratic oath of "do no harm" has determined the indications for cataract surgery over time. Today, doing no harm means operating on cataracts earlier than previously, as this is technically easier than in previous years, when poorer surgical techniques prevailed. However, are we operating on cataracts too early? This review will attempt to highlight the relevant factors that will help to determine the indications for cataract surgery.

The activities of daily vision scale: a useful tool to assess fall risk in older adults with vision impairment

OBJECTIVE

To evaluate the validity of the Activities of Daily Vision Scale (ADVS) as a tool to assess fall risk in older adults with vision impairment.

DESIGN

Cross-sectional assessments of visual function and retrospective collection of fall data.

SETTING

The outpatient medical clinics of an academic tertiary care community hospital.

PARTICIPANTS

Randomly selected sample (n = 143) of older (> or = 65 years) patients seen at the outpatient medical clinics at Nassau County Medical Center in Long Island, New York. These patients had one or more of five ocular conditions: refractive errors (n = 90), cataracts (n = 77), glaucoma (n = 29), diabetic retinopathy (n = 19), and/or macular degeneration (n = 6).

MEASUREMENTS

Visual function, assessed using the ADVS, demonstrated scores ranging from 0 (marked visual disability) to 100 (no visual difficulty). Fall history and the presence of eye disease were based on the self-recall of patients. Fall history was assessed retrospectively over a 1-year period from the time of the interview.

RESULTS

Thirteen percent of the subjects reported having one or more falls during the 1-year period before the time of the interview. These subjects scored significantly lower on the ADVS compared with the scores of the group that did not report falls (74 +/- 22 vs 85 +/- 14, P < .01). Using a cutoff score of 90 points (10% loss of visual function on the ADVS), the ADVS had a 67% sensitivity in identifying those patients who had falls. Among the patients with glaucoma and those with diabetic retinopathy, the ADVS had a 100% sensitivity in identifying those patients who reported a history of falls. In patients with cataracts and refractive errors, the ADVS had a sensitivity of 82% and 64%, respectively, in identifying patients with a history of falls. The number of falls reported by the subjects showed no relationship with the ADVS scores.

CONCLUSION

The results from this study suggest that the ADVS may prove to be a useful tool to assess fall risk in older adults with vision impairment, especially in those persons with glaucoma, diabetic retinopathy, and/or cataracts.