Negative dysphotopsia: the enigmatic penumbra

Migraine is a risk factor for pseudophakic positive dysphotopsia following monofocal lens implantation

OBJECTIVE

To identify neuroadaptation-related risk factors for persistent positive dysphotopsia (>6 months) following monofocal lens implantation.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Patients of an academic institution and a private practice in Saint Louis, Missouri. Inclusion criteria were adults with cataract extraction between January 2010 and April 2021 with monofocal intraocular lens implantation. Exclusion criteria included dementia, <20/40 acuity, visual pathway damage, visual field loss, and significant pathology causing photopsia.

METHODS

Participants were surveyed via telephone.

RESULTS

There were 385 participants (385 eyes), of whom 66 had persistent dysphotopsia (58 positive), 298 had none, and 21 had nonpersistent dysphotopsia. Among the 58 who had positive persistent dysphotopsia, mean Pseudophakic Dysphotopsia Questionnaire 6 (PDQ-6) score was 14.11 (SD, 8.46). There were no significant differences in sex or race. Migraine prevalence was greater among those with dysphotopsia (21.2%) than among those without (11.4%; p = 0.054). History of migraine was associated with an increase in PDQ-6 score of 2.76 points (p = 0.006). Six people in each group had Visual Aura Rating Scale (VARS) scores greater than zero. Mean VARS score was 0.48 for those with dysphotopsia and 0.14 for those without (p = 0.03). History of migraine or increased VARS score, younger age, and female sex were associated with lower satisfaction.

CONCLUSION

History of migraine was associated with increased dysphotopsia severity and decreased patient satisfaction. Although further study with a larger sample size is warranted, these preliminary results highlight the potential of simple questions to individualize lens choice, reduce the risk of dysphotopsia, and improve patient satisfaction.

RELAY INTRASCLERAL 6-0 POLYPROPYLENE-ASSISTED INTRAOCULAR LENS FIXATION: A Retrospective Comparison With Modified Yamane Technique

PURPOSE

To describe a new surgical technique that uses a relay suture to optimize sutureless scleral fixation of intraocular lens in eyes with capsular insufficiency and to evaluate the outcomes of this technique versus Flanged, double needle-guided, scleral fixation of intraocular lens with haptic trimming (modified Yamane approach).

METHODS

Relay intrascleral 6-0 polypropylene sutures with flanges generated at the intraocular ends were used to fixate and securely hold a rigid intraocular lens with haptic eyelets against the inner scleral wall. The results were analyzed at 3-, 6-, and 12-month follow-up.

RESULTS

This retrospective cohort study found that compared with the control group (n = 27), the relay-sutured group (n = 26) had greater mean changes in corneal astigmatism (0.44 vs. -0.52 diopters [D]) and fewer mean degrees of intraocular lens astigmatism (0.62 vs. 1.1 D). The mean intraocular lens decentration was comparable between both the groups; however, in the control group, there was a significant increase in intraocular lens tilt degrees from 3 to 12 months. Moreover, significantly higher proportions of patients with persistent macular edema and iris-optic capture were seen in the control group.

CONCLUSION

The relay-sutured technique may be an alternative to flapless scleral fixation of intraocular lens and provides a stable intraocular lens position with acceptable complication rates.

Effects of alcohol consumption on driving performance in the presence of interocular differences simulated by filters

The role of interocular differences simulated by filters (fog filter and Bangerter foil) on visual and driving performance in alcohol users was assessed. We found that the binocular visual function deteriorates significantly in terms of contrast sensitivity (from 6 to 18 cpd). Additionally, driving performance is significantly impaired under these conditions as evidenced by increased mean speed, standard deviation of the lateral position, distance traveled outside the lane, reaction time and number of collisions. Furthermore, we found that interocular differences due to intraocular scattering and straylight are directly related to an overall reduction in visual and driving performance. This provided a comprehensive perspective from which to understand the relationship between binocular visual function, interocular differences, and driving performance. In practice, our findings contribute to the understanding of the importance of limiting interocular differences, which can be common among presbyopes corrected using the monovision technique, as well as in cases of cataract or other ocular pathology affecting only one eye, or even in cases of cataract surgery of the first eye. These interocular differences can have an adverse impact on road safety, especially when combined with moderate alcohol consumption.

Dysphotopsias or Unwanted Visual Phenomena after Cataract Surgery

Dysphotopsias are unwanted visual phenomena that occur after cataract surgery. They represent some of the most common reasons for patient dissatisfaction after uncomplicated surgery for cataract phacoemulsification with in-the-bag intraocular lens (IOL) implantation. Depending on the form of the optical phenomenon and the effect it poses on vision, dysphotopsias are divided into positive and negative type. Positive dysphotopsias are usually described by patients as glare, light streaks, starbursts, light arcs, rings, haloes, or flashes of light. Negative dysphotopsias are manifested as an arc-shaped shadow or line usually located in the temporal part of the visual field, similar to a temporal scotoma. In addition to their different clinical manifestations, positive and negative dysphotopsia also have different risk factors. Even though up to 67% of patients may experience positive dysphotopsia immediately after surgery, only 2.2% of the cases have persistent symptoms up to a year postoperatively. Surgical intervention may be indicated in 0.07% of cases. The incidence of negative dysphotopsias is up to 26% of all patients; however, by one year postoperatively, the symptoms usually persist in 0.13 to 3% of patients. For both types of dysphotopsia, preoperative patients' education, accurate preoperative diagnostics, and use of an appropriate IOL design and material is mandatory. Despite all these measures, dysphotopsias may occur, and when noninvasive measures fail to improve symptoms, a surgical approach may be considered.

Effect of anatomical differences and intraocular lens design on negative dysphotopsia

PURPOSE

To assess the effect of ocular anatomy and intraocular lens (IOL) design on negative dysphotopsia (ND).

SETTING

Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands.

DESIGN

Ray-tracing study based on clinical data.

METHODS

Ray-tracing simulations were performed to assess the effect of anatomical differences and differences in IOL design on the peripheral retinal illumination. To that end, eye models that incorporate clinically measured anatomical differences between eyes of patients with ND and eyes of pseudophakic controls were created. The anatomical differences included pupil size, pupil centration, and iris tilt. The simulations were performed with different IOL designs, including a simple biconvex IOL design and a more complex clinical IOL design with a convex-concave anterior surface. Both IOL designs were analyzed using a clear edge and a frosted edge. As ND is generally considered to be caused by a discontinuity in peripheral retinal illumination, this illumination profile was determined for each eye model and the severity of the discontinuity was compared between eye models.

RESULTS

The peripheral retinal illumination consistently showed a more severe discontinuity in illumination with ND-specific anatomy. This difference was the least pronounced, 8%, with the frosted edge clinical IOL and the most pronounced, 18%, with the clear edge biconvex IOL.

CONCLUSIONS

These results show that small differences in the ocular anatomy or IOL design affect the peripheral retinal illumination. Therewith, they can increase the severity of ND by up to 18%.

Intensity simulation of photic effects after cataract surgery for off-axis light sources

Photopsia is a photic phenomenon that can be associated with intraocular lenses after cataract surgery. To calculate the relative light intensity of photic effects observed after cataract surgery at the foveal region as the most sensitive region of the retina, photopsia was simulated using the ZEMAX optical design software. The simulations are based on the Liou-Brennan eye model with a pupil diameter of 4.5 mm and incorporating implanted IOLs. The hydrophilic IOLs implanted in the eye model have a power of 21 diopter (D) with an optic diameter of 6 mm and 7 mm. Four different intensity detectors are located in specific regions of the eye in this simulation. The ray-tracing analysis was carried out for variations of incident ray angle of 0° to 90° (temporally) in steps of 1°. Depending on the range of incident ray angle, the light intensity was detected at detectors located on the fovea, nasal side of the retina, or the edge surface of the IOLs. Some portion of the input light was detected at specific incident angles in the foveal region. By altering the IOLs edge design to a fully reflective or anti-reflective surface, the range over which the light intensity is detected on the fovea can be shifted. Additionally, with the absorbing edge design, no intensity was detected at the foveal region for incident ray angles larger than 5°. Therefore an absorbing edge design can make photic effects less disturbing for patients.

The Value of Static Perimetry in the Diagnosis and Follow-up of Negative Dysphotopsia

SIGNIFICANCE

There is a clinical need for a quantitative test to objectively diagnose negative dysphotopsia, especially because the diagnosis is generally assessed using patients' subjective descriptions. In the search of a clinical test to objectify the shadow experienced in negative dysphotopsia, this study excludes static perimetry as suitable evaluation method.

PURPOSE

This study aimed to evaluate the value of static perimetry in the objective assessment and follow-up of negative dysphotopsia.

METHODS

Peripheral 60-4 full-threshold visual field tests were performed in 27 patients with negative dysphotopsia and 33 pseudophakic controls. In addition, 11 patients with negative dysphotopsia repeated the test after an intraocular lens exchange. Both the total peripheral visual field and the averaged peripheral visual field from 50 to 60° eccentricity were compared between patients and controls, and pre-operatively and post-operatively in patients who had an intraocular lens exchange.

RESULTS

The peripheral visual fields from 30 to 60° did not show significant differences between patients with negative dysphotopsia and pseudophakic controls. Analysis of the peripheral visual field from 50 to 60° showed a median [Q1, Q3] of 20.0 [17.1, 22.5] dB in the negative dysphotopsia group compared with 20.1 [15.5, 21.3] dB in the control group (P = .43). Although 82% of patients treated with an intraocular lens exchange subjectively reported improvement of their negative dysphotopsia complaints post-operatively, there were no significant differences in their total peripheral visual field or averaged peripheral visual field from 50 to 60° (P = .92).

CONCLUSIONS

Full-threshold static perimetry with a Goldmann size III stimulus up to 60° eccentricity does not show significant differences between patients with negative dysphotopsia and pseudophakic controls or between measurements before and after intraocular lens exchange. Therefore, this type of static perimetry cannot be used as a quantitative objective test for diagnosis or follow-up of patients with negative dysphotopsia.

Influence of angle alpha on visual quality after implantation of extended depth of focus intraocular lenses

Background

To assess postoperative changes in angle alpha, and to evaluate the postoperative visual quality of patients with different angle alpha values after implantation of extended depth of focus (EDOF) intraocular lenses (IOLs).

Methods

Seventy-nine eyes of 79 patients who had phacoemulsification with EDOF IOLs implantation were enrolled. A cut-off value of 0.3 mm, 0.4 mm, and 0.5 mm in preoperative angle alpha was chosen to divide eyes into groups. Distance, intermediate, and near visual acuities, modulation transfer function (MTF), and aberrations were recorded during a 6-month follow-up. A patient questionnaire was completed.

Results

There were no significant differences in angle alpha postoperatively compared to preoperatively. No significant differences were found in visual acuity and MTF between all groups. With 5 mm pupil diameter, there were significant differences of higher-order aberrations and spherical aberration in ocular aberration and internal aberration between angle alpha<0.4 mm and angle alpha≥0.4 mm. Additionally, significant differences of coma were also added in cut-off value of 0.5 mm. When the value of angle alpha is 0.4 mm or higher, there were significant differences in the score of halos and glare.

Conclusions

Angle alpha did not affect visual acuity, but the value of 0.4 mm or higher in angle alpha affected the visual quality under scotopic conditions and occurrence of halos and glare. For patients with 0.4 mm or higher in angle alpha, the choice to implant a EDOF IOL should be carefully considered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02302-4.

Simulation of photic effects after cataract surgery for off-axis light sources

Photopsia is a phenomenon that sometimes disturbs patients after cataract surgery. To evaluate the impact of the edge design of intraocular lenses (IOL) on the location, shape and relative intensity of photic effects at the retina caused by photopsia in pseudophakic eyes, photopsia was simulated using ZEMAX software. The structural parameters of the pseudophakic eye model are based on the Liou-Brennan eye model parameters with a pupil diameter of 4.5 mm. The IOLs implanted in the eye model have a power of 21 diopter (D) with optical diameter of 6 mm and 7 mm. From the ray-tracing analysis, covering variations of incident ray angle of 50° to 90° from temporally, a photic image is detected at the fovea at specific ray angles of 77.5° (6 mm IOL) and 78.2° (7 mm IOL). This photic image disappears when a thin IOL with an edge thickness of 0 mm or a thick IOL with absorbing edges is replaced in the eye model. With an anti-reflective edge, this photic image remains, but with a fully reflecting edge it disappears at the critical angles and appears with different shapes at other angles. The intensity of this photic image can be reduced by changing the edge design to a frosted surface. Most of the photic patterns in IOLs are not observed with absorbing and thin edge designs. IOLs with anti-reflecting and fully reflecting edges generate disturbing photic effects at different angles on the fovea. IOLs with frosted edges reduce the contrast of the photic effects and make them less disturbing for patients.

Comparison of Visual Outcomes and Patient Satisfaction Following Cataract Surgery with Two Monofocal Intraocular Lenses: Clareon® vs AcrySof® IQ Monofocal

Aim:

This study aimed to compare the performance of two monofocal Intraocular Lenses (IOL) platforms.

Background:

The Clareon® Intraocular Lens (IOL) is a relatively new monofocal lens platform designed to improve postoperative results compared to other monofocal platforms.

Objective:

This study aimed to assess and compare the visual and refractive outcomes, and incidence of YAG capsulotomy of the Clareon® IOL and a standard non-preloaded AcrySof® monofocal IOL following contralateral implantation in patients undergoing cataract surgery.

Methods:

A total of 20 patients (40 eyes; 12 female, average age 72.8±6.4 years) who had undergone contralateral implantation of an AcrySof® IQ monofocal lens (SN60WF or SN6AT; Alcon; Texas, USA) and a Clareon®monofocal lens (CNAOT0; Alcon; Texas, USA) were selected. Uncorrected Distance Visual Acuity (UDVA), Contrast Sensitivity (CS), kinetic perimetry, and refraction were measured 1 month following the second surgery and subjective vision was measured 6 months following the second surgery using a quality-of-life questionnaire.

Results:

There was no difference in postoperative UDVA (P=0.94), CS (P>0.05), or refraction (P=0.64) between eyes that received the Clareon® and AcrySof® IQ lenses. Clareon® eyes had a higher incidence of glare/haloes and positive dysphotopsia while AcrySof® IQ eyes had a higher incidence of negative dysphotopsia. Patient satisfaction was similar between the groups (P=0.86), although 25% of patients reported more clarity in the eye that received the Clareon® lens. The incidence of posterior capsular opacification was low for both groups.

Conclusion:

Clareon® and AcrySof® IQ lenses perform similarly, providing good refractive, visual, and subjective outcomes. Clareon® is available as a preloaded lens option and may reduce PCO and the need for Nd: YAG capsulotomy.

Intraocular lens optic edge design for the prevention of posterior capsule opacification after cataract surgery

BACKGROUND

Posterior capsule opacification (PCO) is a clouding of the posterior part of the lens capsule, a skin-like transparent structure, which surrounds the crystalline lens in the human eye. PCO is the most common postoperative complication following modern cataract surgery with implantation of a posterior chamber intraocular lens (IOL). The main symptoms of PCO are a decrease in visual acuity, 'cloudy', blurred vision and reduced contrast sensitivity. PCO is treated with a neodymium:YAG (Nd:YAG) laser to create a small opening in the opaque capsule and regain a clear central visual axis. This capsulotomy might cause further ocular complications, such as raised intraocular pressure or swelling of the central retina (macular oedema). This procedure is also a significant financial burden for health care systems worldwide. In recent decades, there have been advances in the selection of IOL materials and optimisation of IOL designs to help prevent PCO formation after cataract surgery. These include changes to the side structures holding the lens in the centre of the lens capsule bag, called IOL haptics, and IOL optic edge designs.

OBJECTIVES

To compare the effects of different IOL optic edge designs on PCO after cataract surgery.

SEARCH METHODS

We searched CENTRAL, Ovid MEDLINE, Ovid Embase, Latin American and Caribbean Health Sciences Literature Database (LILACS), the ISRCTN registry, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) up to 17 November 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared different types of IOL optic edge design. Our prespecified primary outcome was the proportion of eyes with Nd:YAG capsulotomy one year after surgery. Secondary outcomes included PCO score, best-corrected distance visual acuity (BCDVA) and quality of life score at one year. Due to availability of important long-term data, we also presented data at longer-term follow-up which is a post hoc change to our protocol.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane and the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

We included 10 studies (1065 people, 1834 eyes) that compared sharp- and round-edged IOLs. Eight of these studies were within-person studies whereby one eye received a sharp-edged IOL and the fellow eye a round-edged IOL. The IOL materials were acrylic (2 studies), silicone (4 studies), polymethyl methacrylate (PMMA, 3 studies) and different materials (1 study). The studies were conducted in Austria, Germany, India, Japan, Sweden and the UK. Five studies were at high risk of bias in at least one domain. We judged two studies to be at low risk of bias in all domains. There were few cases of Nd:YAG capsulotomy at one year (primary outcome): 1/371 in sharp-edged and 4/371 in round-edged groups. The effect estimate was in favour of sharp-edged IOLs but the confidence intervals were very wide and compatible with higher or lower chance of Nd:YAG capsulotomy in sharp-edged compared with round-edged lenses (Peto odds ratio (OR) 0.30, 95% CI 0.05 to 1.74; I² = 0%; 6 studies, 742 eyes). This corresponds to seven fewer cases of Nd:YAG capsulotomy per 1000 sharp-edged IOLs inserted compared with round-edged IOLs (95% CI 9 fewer to 7 more). We judged this as low-certainty evidence, downgrading for imprecision and risk of bias. A similar reduced risk of Nd:YAG capsulotomy in sharp-edge compared with round-edge IOLs was seen at two, three and five years but as the number of Nd:YAG capsulotomy events increased with longer follow-up this effect was more precisely measured at longer follow-up: two years, risk ratio (RR) 0.35 (0.16 to 0.80); 703 eyes (6 studies); 89 fewer cases per 1000; three years, RR 0.21 (0.11 to 0.41); 538 eyes (6 studies); 170 fewer cases per 1000; five years, RR 0.21 (0.10 to 0.45); 306 eyes (4 studies); 331 fewer cases per 1000. Data at 9 years and 12 years were only available from one study. All studies reported a PCO score. Four studies reported the AQUA (Automated Quantification of After-Cataract) score, four studies reported the EPCO (Evaluation of PCO) score and two studies reported another method of quantifying PCO. It was not possible to pool these data due to the way they were reported, but all studies consistently reported a statistically significant lower average PCO score (of the order of 0.5 to 3 units) with sharp-edged IOLs compared with round-edged IOLs. We judged this to be moderate-certainty evidence downgrading for risk of bias. The logMAR visual acuity score was lower (better) in eyes that received a sharp-edged IOL but the difference was small and likely to be clinically unimportant at one year (mean difference (MD) -0.06 logMAR, 95% CI -0.12 to 0; 2 studies, 153 eyes; low-certainty evidence). Similar effects were seen at longer follow-up periods but non-statistically significant data were less fully reported: two years MD -0.01 logMAR (-0.05 to 0.02); 2 studies, 311 eyes; three years MD -0.09 logMAR (-0.22 to 0.03); 2 studies, 117 eyes; data at five years only available from one study. None of the studies reported quality of life. Very low-certainty evidence on adverse events did not suggest any important differences between the groups.

AUTHORS' CONCLUSIONS

This review provides evidence that sharp-edged IOLs are likely to be associated with less PCO formation than round-edged IOLs, with less Nd:YAG capsulotomy. The effects on visual acuity were less certain. The impact of these lenses on quality of life has not been assessed and there are only very low-certainty comparative data on adverse events.

Evaluation of intraocular lens position and retinal shape in negative dysphotopsia using high-resolution magnetic resonance imaging

PURPOSE

To assess potential relationships of intraocular lens (IOL) position and retinal shape in negative dysphotopsia (ND).

SETTING

Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands.

DESIGN

Case-control study.

METHODS

High-resolution ocular magnetic resonance imaging (MRI) scans were performed in patients with ND and pseudophakic controls, and subsequently used to determine the displacement and tilt of the in-the-bag IOL about the pupil and iris. In addition, anterior segment tomography was used to assess the iris-IOL distance. Furthermore, the retinal shape was quantified from the MRI scans by fitting an ellipse to the segmented inner boundary of the retina. Both the IOL position and retinal shape were compared between groups to assess their potential role in the etiology of ND.

RESULTS

In total, 37 patients with ND and 26 pseudophakic controls were included in the study. The mean displacement and tilt of the IOL were less than 0.1 mm and 0.5 degrees, respectively, in both groups and all directions. The corresponding mean iris-IOL distance was 1.1 mm in both groups. Neither of these values differed statistically significantly between groups (all P values >.6). The retinal shape showed large variations but was not statistically significantly different between the groups in both the left-right (P = .10) and the anterior-posterior (P = .56) directions.

CONCLUSIONS

In this study, the in-the-bag IOL position and retinal shape did not statistically significantly differ between patients with ND and the general pseudophakic population. Given the large variation in retinal shape between subjects, however, it could still be an important factor in a multifactorial origin of ND.

Distinct differences in anterior chamber configuration and peripheral aberrations in negative dysphotopsia

Clinical evaluations combined with ray-tracing analyses in patients with negative dysphotopsia supported the role of an increased angle κ.

Purpose:

To provide insights into the anatomical characteristics associated with negative dysphotopsia using quantitative clinical data.

Setting:

Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands.

Design:

Case-control study.

Methods:

Anterior chamber tomography and peripheral aberrometry were measured in 27 pseudophakic patients with negative dysphotopsia and 30 pseudophakic control subjects. Based on these measurements, the total corneal power, anterior chamber depth, pupil location and diameter, iris tilt, and peripheral ocular wavefront up to 30 degrees eccentricity were compared between both groups. In addition, ray-tracing simulations using pseudophakic eye models were performed to establish a connection between these clinical measurements and current hypotheses on the etiology of negative dysphotopsia.

Results:

Twenty-seven patients with negative dysphotopsia and 25 pseudophakic controls were included in the analysis. The patients with negative dysphotopsia had a smaller (P = .03/P = <.01) and more decentered (P < .01) pupil than that of the pseudophakic controls. In addition, an increased temporal-tilted iris (P < .01) and an asymmetric peripheral aberration profile were observed in patients with negative dysphotopsia, of which the latter was also apparent in several ray-tracing models. The combination of these in vivo results and ray-tracing simulations indicated that patients with negative dysphotopsia had a temporal-rotated eye, which confirmed the hypothesized relation between negative dysphotopsia and an increased angle κ.

Conclusions:

Patients with negative dysphotopsia had a smaller pupil and an increased angle κ, which made them more susceptible to experiencing a shadow in the temporal visual field.

Incidence and causes of negative dysphotopsia after uncomplicated cataract surgery - A randomized clinical trial

Purpose:

The purpose of this study is to find incidence of negative dysphotopsia (ND) in eyes undergoing clear corneal phacoemulsification and identify its causes including corneal wound hydration and type of intraocular lens (IOL).

Methods:

In this randomized clinical trial, consenting adult patients undergoing phacoemulsification were randomized to receive a hydrophobic (Alcon Acrysof^® SN60WF) or a hydrophilic acrylic IOL (CT Asphina^® 603P, Carl Zeiss Meditec) in a 1:1 ratio. At time of surgery, eyes were again randomized in 1:1 fashion to receive stromal wound hydration or not (n = 80 each in four groups). Primary outcome measure was the incidence of ND between eyes receiving stromal hydration versus no hydration. Those with ND were observed for 5 years after surgery.

Results:

Of the 320 eyes, 29 (9.06%) reported ND of which 24 (83%) were transient. Eyes with wound hydration had significantly higher proportion of ND (n = 21/160, 13%) compared to no hydration (n = 8/160, 5%) (P = 0.01). Additionally, eyes with wound hydration were three times more likely to experience ND (odds ratio = 3.29, 95% CI = 1.3–8.2, P = 0.01). Majority of eyes (20/21, 95%) with ND after hydration had it transiently while half (4/8, 50%) of those with ND without wound hydration had it persistently at 6 weeks (P < 0.001) and continued to experience ND for 5 years but did not request intervention.

Conclusion:

ND occurred in 9% cases with majority being transient. Corneal wound hydration led to significant higher likelihood of experiencing transient ND. Those with persistent ND for more than 6 weeks (1.5%) continue to experience ND for at least 5 years.

Dysphotopsiae and functional quality of vision after implantation of an intraocular lens with a 7.0 mm optic and plate haptic design

PURPOSE

To determine the impact of IOL with 7.0 mm optic and plate haptic design on incidence of dysphotopsiae and visual functions after cataract surgery.

SETTING

Day-care clinic.

DESIGN

A prospective monocentric randomized patient-blinded comparative clinical study.

METHODS

Following preoperative measurements, patients underwent cataract surgery with implantation of two IOL designs - with 7.0 mm optic and plate haptics (group 1) or with 6.0 mm optic and C-loop haptics (group 2). In month 1, 3 and 12 follow-ups patients were examined, answered a questionnaire regarding satisfaction, spectacle dependence, frequency and extent of positive and negative dysphotopsiae, and underwent contrast sensitivity, mesopic vision and glare sensitivity testing. The data were analyzed as nominal, ordinal and metric with Chi-Square, Mann-Whitney-U, Wilcoxon and t-tests.

RESULTS

Group 1 comprised 57 eyes (43 patients) and group 2 comprised 63 eyes (43 patients). Corrected distance visual acuity was the same between groups throughout the study. Group 1 showed significantly lower incidence of positive and negative dysphotopsiae in month 1 follow-up (p=0.021 and 0.015, respectively) and a higher satisfaction rate in month 3 follow-up (p=0.006). Mean contrast sensitivity and mesopic vision with and without glare were the same in both groups. Positive dysphotopsiae cases in month 12 follow-up revealed lower photopic contrast sensitivity (p=0.005, 0.036 and 0.047, respectively), longer AL and greater preoperative pupil dynamics (p=0.04 and 0.06).

CONCLUSIONS

The IOL design with 7.0 mm optic diameter and plate haptics reduces dysphotopsiae, provides good visual acuity, contrast sensitivity, mesopic vision with and without glare and high patient satisfaction.

Angle alpha orientation and magnitude distribution in a cataract surgery population

PURPOSE

To report normative angle alpha orientation and magnitude distribution in a cataract surgery patient population.

SETTING

U.S. academic medical center.

DESIGN

Retrospective review.

METHODS

A total of 11 871 wavefront aberrometer/corneal topographer angle alpha measurements were performed over 40 months, yielding 8773 bilateral measurements (73.9%) with zero bad wavefront datapoints. The analysis was limited to the first right-eye scan for 3382 unique patients. The angle alpha magnitudes (millimeters) and orientations (degrees) were analyzed for these unique right eyes.

RESULTS

For the 3,382 unique patients, the mean angle alpha magnitude was 0.44 ± 0.15 mm (median, 0.44 mm; 25th and 75th percentiles 0.34 mm, 0.53 mm). Angle alpha orientation was predominantly horizontal (P < .01), with a mean of 186 ± 32 degrees. The expected point of intraocular lens (IOL) centration (EPIC) based on the geometric center of the corneal limbus was temporal to the visual axis in 3212 eyes (95%), nasal in 92 eyes (2.7%), inferior in 56 eyes (1.7%), and superior in 22 eyes (0.6%). The mean angle alpha magnitude was 0.3 mm or less in 607 eyes (18%) and 0.5 mm or greater in 1089 eyes (32%).

CONCLUSIONS

Angle alpha is a predominantly horizontal phenomenon with a mean EPIC of 0.44 mm temporal to the visual axis. This information may assist in determining eligibility for patients in multifocal IOL implantation.

Pseudophakic negative dysphotopsia and intraocular lens orientation: a prospective double-masked randomized controlled trial

PURPOSE

To determine whether horizontal orientation of the intraocular lens optic-haptic junctions has an effect on the incidence of pseudophakic negative dysphotopsia.

METHODS

Single-centre prospective double-masked randomized controlled trial. 220 eyes of 201 participants undergoing routine cataract surgery were randomized to receive their intraocular lens either orientated with the optic-haptic junctions at 180° ('horizontal') or without manipulation following implantation (control). Patients were excluded according to age (<19 and > 99 years), coexisting eye disease affecting visual function and insufficient cognitive function to complete the study. In the fourth postoperative week, a telephone interview was conducted to determine rates of negative dysphotopsia. The data were analysed to provide the relative risk of negative dysphotopsia with horizontal orientation of the intraocular lens (IOL) optic-haptic junctions compared with standard treatment.

RESULTS

Orientating the IOL optic-haptic junctions horizontally halved the incidence of pseudophakic negative dysphotopsia in the fourth postoperative week (9/110 in the intervention group; 18/110 in the control group; RR: 0.50, 95% confidence interval: 0.235-1.064, p = 0.072). The overall incidence of negative dysphotopsia was 12.2% (27/220 participating eyes). No intraoperative adverse effects of intraocular lens rotation were reported.

CONCLUSION

The simple intraoperative manoeuvre of rotating the intraocular lens to orientate the optic-haptic junctions at 180° may be a safe and effective measure to reduce the risk of developing postoperative pseudophakic negative dysphotopsia in the first postoperative month. This is the first report that demonstrates the benefit of horizontal optic-haptic junction positioning to be sustained beyond the first postoperative day.

Pseudophakic Dysphotopsia: Review of Incidence, Cause, and Treatment of Positive and Negative Dysphotopsia

We reviewed the literature concerning positive dysphotopsia (PD) and negative dysphotopsia (ND) regarding cause, incidence, and clinical and surgical management. In addition, we summarized our surgical experience in managing dysphotopsia. A PubMed review, limited to English language articles, yielded 149 citations; multifocal (diffractive optic) and phakic intraocular lens (IOL) dysphotopsia were excluded. Overall, 39 articles were determined to be relevant for the objectives of this investigation. Regarding PD, 7 articles corroborated that the cause of PD is related primarily to internal reflection of oblique light rays that strike the square (truncated) edge of the IOL and are reflected onto the retinal surface. No round-edged foldable IOLs are available in the United States at this time, although IOLs modified with a round anterior edge and square posterior edge show a trend toward decreased incidence of PD. High index of refraction (I/R), surface reflectivity, and IOL optic design are additional causative factors for PD. Regarding the authors' surgical experience, changing the optic material to have a lower I/R improved PD symptoms in the large majority of patients. The cause of ND seems to be multifactorial and less well understood, with some disparity between clinical and laboratory findings. Four articles that explore using ray-tracing optical modeling suggest an "illumination gap," in which some temporally incident light rays to the nasal retina pass anterior to the IOL and some are refracted posteriorly by the IOL, resulting in a gap and resultant temporal shadow. However clinically, ND is associated invariably with well-centered in-the-bag IOLs. Other implicating factors include nasal anterior capsule override, haptic orientation, large-angle κ value, and high hyperopia. Persistent ND has been treated successfully or reduced with reverse (anterior) optic capture, sulcus IOL placement, piggyback IOLs, and neodymium:yttrium-aluminum-garnet nasal capsulectomy. Two articles reference a new optic edge designed to capture the anterior capsulotomy, mimicking reverse optic capture. Persistent dysphotopsia after cataract surgery is a significant cause for patient dissatisfaction. The cause and management of both ND and PD are of significance, and new IOL designs and alternative surgical strategies may help to mitigate these unintended side effects of IOL implantation.

Experimental Model of Far Temporal Field Negative Dysphotopsia Generated in Phakic Eyes

Purpose

The axial separation between the iris and the intraocular lens (IOL) in pseudophakic eyes can cause rays originating from the far temporal field to miss the IOL, resulting in negative dysphotopsia (ND). We developed an experimental model to test the hypothesis that obstruction of rays from the far temporal field can generate ND and an accompanying loss of visual sensitivity in the far temporal field.

Methods

The right eyes of 10 phakic subjects were fitted with soft contact lenses containing a 5.50-mm central clear zone and a 12-mm outer diameter opaque annulus. In three of the subjects, eyes were dilated with 1% tropicamide solution, and effective aperture diameters were determined optically (pupil camera) and psychophysically (narrow beam detection). Visual field extent (Goldmann bowl) and temporal and inferotemporal meridian sensitivities (Octopus perimeter) were measured. A wide-angle model was constructed to quantify the impact of the annular opacity on retinal illuminance.

Results

All 10 subjects observed a dark crescent in the far temporal and inferotemporal fields. The opaque annulus reduced effective horizontal pupil diameters from 8 mm to 5.5 mm on-axis and from >2 mm to <1 mm at 90°. Perimetry revealed a 10° reduction in temporal and inferotemporal field extent and increasing loss of sensitivity beyond 70°. The wide-angle model confirmed significant vignetting (>50% beyond 70°), approaching zero retinal illuminance beyond 85°.

Conclusions

Vignetting of rays originating from the far temporal field by axially separated apertures can create symptoms mirroring perceptual reports of negative dysphotopsia in symptomatic pseudophakic patients.

Simulated images of intraocular lens negative dysphotopsia and visual phenomena

Simulated images were generated using an extended source to illustrate peripheral dark shadows in pseudophakic eye models. The shadows are a consequence of the intraocular lens being much smaller than the natural crystalline lens, which limits the extent of the focused image. Compensation is made for the cosine intensity falloff due to pupil obliquity, and the images are envisaged as being displayed on polar plots of visual angle corresponding to approximate retinal locations. Additional retinal illumination from light missing the lens reduces the shadow effect as the pupil diameter increases, in agreement with clinical observations. Lenses with two different cross-sectional profiles were evaluated, which both have shadows at about 85°, but with different characteristics. The iris thickness was found to affect the shadows by occluding peripheral rays. Images were also generated for a point source with a 5 mm pupil, where a double image is created for visual angles as low as 50°, which may contribute to visual phenomena at night. This type of modeling may help with patient evaluations and discussions.

In-the-bag nasal intraocular lens optic truncation for treatment of negative dysphotopsia

We describe in-the-bag nasal intraocular lens (IOL) optic truncation, a new technique for the treatment of negative dysphotopsia. After a plane is created between the nasal capsular bag and the IOL, micrograspers and intraocular scissors are used to amputate the nasal optic edge. The amputation is to reduce the optical impact of the IOL edge and nasal anterior capsule on the occurrence of negative dysphotopsia. The technique addresses many of the proposed mechanisms contributing to the development of negative dysphotopsia and can theoretically be used in all patients with chronic symptomatology. In the case we describe, the dysphotopsia resolved immediately after in-the-bag nasal IOL optic truncation.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

Effect of active evaluation on the detection of negative dysphotopsia after sequential cataract surgery: discrepancy between incidences of unsolicited and solicited complaints

PURPOSE

To evaluate the incidence of negative dysphotopsia after sequential cataract surgery.

METHODS

Retrospective cohort study. The incidence of negative dysphotopsia was assessed by retrospective reviewing of medical records and interviews with patients between 2 and 4 months after sequential cataract surgery. Inclusion criteria were uncomplicated surgery, postoperative corrected distance visual acuity (CDVA) ≥20/25 Snellen and the absence of ocular comorbidity. The majority of intra-ocular lens (IOL) implants were one-piece AcrySof SN60WF (161 eyes). Other IOLs (29 eyes) were toric (SN6AT3-6), spherical (SN60AT), three-piece (MN60MA) and multifocal (ReSTOR SN6AD1, PanOptix TFNT00 and Finevision Micro F trifocal).

RESULTS

The study population was comprised of 95 patients with a mean age of 72 ± 10 years. Unsolicited complaints of negative dysphotopsia were reported by eight patients (8%), and two of them had a resolution of symptoms within 1 month of follow-up. Eighteen patients (19%) reported negative dysphotopsia at the time of the interview. Two patients reported bothersome negative dysphotopsia, and one of them was successfully treated with implantation of a supplementary IOL in the ciliary sulcus. Patients with negative dysphotopsia were younger than patients without dysphotopsia (p = 0.045) and had shorter axial eye length (p = 0.04), a tendency for higher IOL power (p = 0.09) and a higher CDVA (p = 0.001).

CONCLUSION

The incidence of unsolicited negative dysphotopsia after sequential cataract surgery appears to be a substantial underestimation of complaints identified in active interviewing. Although symptoms are not bothersome in the majority of cases, some patients with undiagnosed severe negative dysphotopsia may benefit from reassurance or secondary treatment.

Mini-review: Far peripheral vision

The region of far peripheral vision, beyond 60 degrees of visual angle, is important to the evaluation of peripheral dark shadows (negative dysphotopsia) seen by some intraocular lens (IOL) patients. Theoretical calculations show that the limited diameter of an IOL affects ray paths at large angles, leading to a dimming of the main image for small pupils, and to peripheral illumination by light bypassing the IOL for larger pupils. These effects are rarely bothersome, and cataract surgery is highly successful, but there is a need to improve the characterization of far peripheral vision, for both pseudophakic and phakic eyes. Perimetry is the main quantitative test, but the purpose is to evaluate pathologies rather than characterize vision (and object and image regions are no longer uniquely related in the pseudophakic eye). The maximum visual angle is approximately 105⁰, but there is limited information about variations with age, race, or refractive error (in case there is an unexpected link with the development of myopia), or about how clear cornea, iris location, and the limiting retina are related. Also, the detection of peripheral motion is widely recognized to be important, yet rarely evaluated. Overall, people rarely complain specifically about this visual region, but with "normal" vision including an IOL for >5% of people, and increasing interest in virtual reality and augmented reality, there are new reasons to characterize peripheral vision more completely.

The Complexities of Negative Dysphotopsia

The appearance of a dark shadow in the temporal periphery, otherwise known as negative dysphotopsia, continues to be a problem for some patients after routine uncomplicated cataract surgery. Etiologies include type and design of intraocular lens (IOL), anatomical features and dimensions of the eye, pupil size, angle kappa, relationship of the optic to the anterior capsule, and the position of the optic/haptic junction of the IOL. Although the primary etiology remains controversial, it is clear that the cause is multifactorial. All of the factors should be considered when attempting to prevent or treat this phenomenon.

Functional Magnetic Resonance Imaging to Assess the Neurobehavioral Impact of Dysphotopsia with Multifocal Intraocular Lenses

PURPOSE

To investigate the association between dysphotopsia and neural responses in visual and higher-level cortical regions in patients who recently received multifocal intraocular lens (IOL) implants.

DESIGN

Cross-sectional study.

PARTICIPANTS

Thirty patients 3 to 4 weeks after bilateral cataract surgery with diffractive IOL implantation and 15 age- and gender-matched control subjects.

METHODS

Functional magnetic resonance imaging (fMRI) was performed when participants viewed low-contrast grating stimuli. A light source surrounded the stimuli in half of the runs to induce disability glare. Visual acuity, wavefront analysis, Quality of Vision (QoV) questionnaire, and psychophysical assessment were performed.

MAIN OUTCOME MEASURES

Cortical activity (blood oxygen level dependent [BOLD] signal) in the primary visual cortex and in higher-level brain areas, including the attention network.

RESULTS

When viewing low-contrast stimuli under glare, patients showed significant activation of the effort-related attention network in the early postoperative period, involving the frontal, middle frontal, parietal frontal, and postcentral gyrus (multisubject random-effects general linear model (GLM), P < 0.03). In contrast, controls showed only relative deactivation (due to lower visibility) of visual areas (occipital lobe and middle occipital gyrus, P < 0.03). Patients also had relatively stronger recruitment of cortical areas involved in learning (anterior cingulate gyrus), task planning, and solving (caudate body). Patients reporting greater symptoms induced by dysphotic symptoms showed significantly increased activity in several regions in frontoparietal circuits, as well as cingulate gyrus and caudate nucleus (q < 0.05). We found no correlation between QoV questionnaire scores and optical properties (total and higher order aberration, modulation transfer function, and Strehl ratio).

CONCLUSIONS

This study shows the association between patient-reported subjective difficulties and fMRI outcomes, independent of optical parameters and psychophysical performance. The increased activity of cortical areas dedicated to attention (frontoparietal circuits), to learning and cognitive control (cingulate), and to task goals (caudate) likely represents the beginning of the neuroadaptation process to multifocal IOLs.

Research Article. The Prevalence of Dysphotopsia in Patients with Recent Cataract Surgery

Pseudophakic dysphotopsia are becoming increasingly important as unwanted side effect after cataract surgery. Objective: The purpose of this study is to compare the photic symptoms experienced by patients after cataract surgery. Material and method: This is a prospective study that included 105 eyes from 99 patients, which underwent uncomplicated phacoemulsification and IOL implantation, between June 2015 and June 2016, performed at Ophthalmology Clinic Tg Mureș. Patients without visually consequential ocular co-morbidity completed a questionnaire, designed to assess subjectively perceived visual functioning and identify symptoms of dysphotopsia. Results: From the total number of patient, hydrophobic lenses were implanted in 95 patients and 10 patients received hydrophilic lenses. Photic effects were reported in 18% of treated eyes. Although the percentage of dysphotopsia is higher in the hydrophobic lenses category, there was no significant statistical difference between the two categories. Conclusion: The incidence and significance should not be overlooked, thus visual acuity is not enough for evaluating postoperative visual function.

Intraocular lens optics and aberrations

PURPOSE OF REVIEW

This review outlines concepts in intraocular lens (IOL) optics and aberrations important both for current IOLs and for new IOLs in development.

RECENT FINDINGS

Optical aberrations make a significant impact on the laboratory and clinical performance of IOLs, especially under mesopic and low-contrast conditions. Minimizing or correcting these aberrations can potentially improve visual function. Strategic management of aberrations can have clinical utility for extended depth of focus and presbyopia correction.

SUMMARY

All IOLs affect ocular aberrations in some manner. It is important for clinicians and researchers to understand the implications how any residual aberrations could affect visual quality, visual side-effects, and depth of focus.

Efficacy and Safety of Femtosecond Laser-Assisted Cataract Surgery Compared with Manual Cataract Surgery: A Meta-Analysis of 14 567 Eyes

TOPIC

To investigate the efficacy and safety of femtosecond laser-assisted cataract surgery (FLACS) relative to manual cataract surgery (MCS).

CLINICAL RELEVANCE

It is unclear whether FLACS is more efficacious and safe relative to MCS.

METHODS

A literature search of MEDLINE, EMBASE, and Scopus from 2007 to March 2016 was conducted. Studies containing both FLACS and MCS arms that reported on relevant efficacy and/or safety parameters were included. Weighted mean differences (WMDs) and risk ratios (RRs) with 95% confidence intervals (CIs) were calculated.

RESULTS

From 2802 screened articles, 14 567 eyes from 15 randomized controlled trials and 22 observational cohort studies were included. For primary visual and refractive outcomes, no statistically significant difference was detected between FLACS and MCS in uncorrected distance visual acuity (WMD, -0.02; 95% CI, -0.04 to 0.01; P = 0.19), corrected distance visual acuity (WMD, -0.01; 95% CI, -0.02 to 0.01; P = 0.26), and mean absolute error (WMD, -0.02; 95% CI, -0.07 to 0.04; P = 0.57). In terms of secondary surgical end points, there was a statistically significant difference in favor of FLACS over MCS for effective phacoemulsification time (WMD, -3.03; 95% CI, -3.80 to -2.25; P < 0.001), capsulotomy circularity (WMD, 0.16; 95% CI, 0.11-0.21; P < 0.001), postoperative central corneal thickness (WMD, -6.37; 95% CI, -11.88 to -0.86; P = 0.02), and corneal endothelial cell reduction (WMD, -55.43; 95% CI, -95.18 to -15.69; P = 0.006). There was no statistically significant difference between FLACS and MCS for total surgery time (WMD, 1.25; 95% CI, -0.08 to 2.59; P = 0.07), capsulotomy circularity using a second formula (WMD, 0.05; 95% CI, -0.01 to 0.12; P = 0.10), and corneal endothelial cell count (WMD, 73.39; 95% CI, -6.28 to 153.07; P = 0.07). As well, there was a significantly higher concentration of prostaglandins after FLACS relative to MCS (WMD, 198.34; 95% CI, 129.99-266.69; P < 0.001). Analysis of safety parameters revealed that there were no statistically significant differences in the incidence of overall complications between FLACS and MCS (RR, 2.15; 95% CI, 0.74 to 6.23; P = 0.16); however, posterior capsular tears were significantly more common in FLACS versus MCS (RR, 3.73; 95% CI, 1.50-9.25; P = 0.005).

CONCLUSIONS

There were no statistically significant differences detected between FLACS and MCS in terms of patient-important visual and refractive outcomes and overall complications. Although FLACS did show a statistically significant difference for several secondary surgical outcomes, it was associated with higher prostaglandin concentrations and higher rates of posterior capsular tears.

Negative dysphotopsia: A perfect storm

The objective of this review was to provide a summary of the peer-reviewed literature on the etiologies of negative dysphotopsia that occurs after routine cataract surgery. A search of PubMed, Google Scholar, and Retina Medical identified 59 reports. Negative dysphotopsia has been associated with many types of intraocular lenses (IOLs), including hydrophobic and hydrophilic acrylic, silicone, and 1-piece and 3-piece designs. Proposed etiologies include edge design, edge smoothness, edge thickness, index of refraction of the IOL, pupil size, amount of functional nasal retina, edema from the clear corneal incision, distance between the iris and IOL, amount of pigmentation of the eye, corneal shape, prominent globe and shallow orbit, and interaction between the anterior capsulorhexis and IOL. Treatments include a piggyback IOL, reverse optic capture, dilation of the pupil, constriction of the pupil, neodymium:YAG capsulotomy of the nasal portion of the anterior capsule, IOL exchange with round-edged optics, and time alone. This review summarizes the findings.

FINANCIAL DISCLOSURE

Dr. Henderson is a consultant to Alcon Laboratories, Inc., Abbott Medical Optics, Inc., Bausch & Lomb, and Genzyme Corp. Neither author has a financial or proprietary interest in any material or method mentioned.

Ghost-image analysis in phakic intraocular lenses with central hole as a potential cause of dysphotopsia

PURPOSE

To analyse the optical effect of an artificial hole in the optic centre of posterior chamber phakic intraocular lenses.

SETTING

Institute of Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany.

DESIGN

Experimental simulation study.

METHODS

Four eye models with an ametropia of -4 D, -8 D, +4 D, and +8 D were created in the ray tracing software ASAP. Refractive correction of these models was implemented with a model of an Implantable Collamer Lens (ICL). Each eye was set up twice with 1 eye receiving a conventional ICL without a central hole and the second an ICL with a central hole. Ray bundles were traced for lateral visual field angles from 0 to 60 degrees in steps of 1 degree. Ray propagation and retinal illumination were then compared between the 2 ICL models.

RESULTS

All eye models showed ghost images originating from the anterior surface of the ICL. Eye models with the ICL with central hole showed additional light spots in the peripheral areas of the retina originating from reflections at the cylindrical wall of the central hole in the ICL. The average intensity of ghost images in the temporal retinal hemisphere was between 30 and 40 dB less than the maximum intensity of the primary image.

CONCLUSION

A central hole within a posterior chamber phakic intraocular lens may cause stray light and ghost images (positive dysphotopsia) although the on-axis visual quality of the eye with the ICL is mostly unaffected.

FINANCIAL DISCLOSURE

The authors have no financial interest in any of the material presented in this paper.

Is the Memory Effect of the Blind Spot Involved in Negative Dysphotopsia after Cataract Surgery?

We present novel clinical observations on negative dysphotopsia (ND) in eyes that have undergone cataract surgery. In the past, shadow effects were alleged to be located in the far peripheral temporal visual field 50° to 100° away from the optical axis. In a small series of eight patients we found evidence of photic effects, described by the patients as shadows in the periphery that were objectively located much more centrally. In all cases, we could find an association of these phenomena with the blind spot. We hypothesize that the memory effect of the blind spot which is dislocated and changed in magnification due to replacement of the crystalline lens could be one determinant for pseudophakic ND. The scotoma of the optic nerve head and the main arteries and veins of the phakic eye are displaced in the pseudophakic eye depending on the specific characteristics and position of the intraocular lens within the eye.

Vignetting and negative dysphotopsia with intraocular lenses in "far peripheral vision"

At very large visual angles, vignetting can occur at the edge of an intraocular lens (IOL), because it is much smaller than the natural crystalline lens that it replaces. Ray trace calculations show that, by 80-90 deg of input visual angle, it is possible that about half the light is no longer focused by the IOL. This may create curved, peripheral, shadowlike regions, which are a clinical characteristic of negative dysphotopsia. The imaging characteristics for this "far peripheral vision" region are different from those of a phakic eye, whether or not negative dysphotopsia is experienced.