Satisfaction and dysphotopsia in the pseudophakic patient

Glare prediction and mechanism of adaptation following implantation of hydrophilic and hydrophobic intraocular lenses

Purpose

Glare is a known side effect of intraocular lens (IOL) implantation, affected principally by IOL material and optics, although it is reported subjectively to decrease in impact with time. However, little objective data have been published on changes over time, how these relate to subjective reports, and whether those who will report greater glare symptoms can be predicted prior to IOL implantation.

Methods

A total of 32 patients (aged 72.4 ± 8.0 years) with healthy eyes were implanted bilaterally with hydrophilic 600s (Rayner, Worthing, UK) or hydrophobic Acrysof (Alcon, Texas, USA) acrylic IOLs (n = 16 each, randomly assigned). Each patient reported their dysphotopsia symptoms subjectively using the validated forced choice photographic questionnaire for photic phenomena, and halo size resulting from a bright light in a dark environment was quantified objectively in eight orientations using the Aston Halometer. Assessment was performed binocularly pre-operatively and at 1, 2, 3, and 4 weeks after IOL implantation.

Setting

The study was carried out at the National Health Service Ophthalmology Department, Queen Elizabeth Hospital, Birmingham, UK.

Results

Visual acuity (average 0.37 ± 0.26 logMAR) did not correlate with subjective glare (r = 0.184, p = 0.494) or objective glare (r = 0.294, p = 0.270) pre-surgery. Objective halo size (F = 112.781, p < 0.001) decreased with cataract removal and IOL implantation and continued to decreased over the month after surgery. Subjective dysphotopsia complaints (p < 0.001) were also greater pre-surgery, but did not change thereafter (p = 0.228). In neither case was there a difference with IOL material (p > 0.05). It was not possible to predict post-surgery dysphotopsia from symptoms or a ratio of symptoms to halo size pre-surgery (p > 0.05).

Conclusions

Subjective dysphotopsia and objective halos caused by cataracts are greatly reduced by implantation of IOL after cataract removal causing few perceivable symptoms. However, objective measures are able to quantify a further reduction in light scatter over the first month post-IOL implantation, suggesting that any subjective effects over this period are due to the healing process and not due to neuroadaptation.

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.

Predictors of Photic Phenomena with a Trifocal IOL

Aim

To assess predictive factors associated with glares and halos in patients undergoing cataract surgery with PanOptix trifocal IOL implantation.

Methods

Single-center retrospective study. One hundred and forty eyes from 70 patients with cataract were bilaterally implanted with a trifocal PanOptix aspherical diffractive lens between 2017 and 2019 and followed-up for six months. All patients were evaluated for refraction, corneal topography, and aberrometry pre- and post-operatively. Patients were assessed at 1 day, 6 days, 1 and 6 months after surgery. One and six months post-operatively patients were asked to complete a satisfaction questionnaire that included photic phenomena assessment. Main outcome measures were photic phenomena at 1 and 6 months of follow-up. Predictors of photic phenomena at 1 and 6 months were also analyzed.

Results

A higher corneal coma was associated with more mild halos at 6 months with no association regarding other degrees of severity. The lower the age the higher the glare or halos, the higher the lens thickness and the lower the anterior chamber depth or chord µ the less halos at 1 month. A significant proportion of patients had more none/mild compared to moderate/severe glare and halos both at 1 and 6 months post-operatively. Baseline BCVA was the only predictor of halos at 1 month and glare and halos at 6 months post-surgery.

Conclusion

On multivariate regression analyses, the only predictor of photic phenomena was baseline visual acuity, suggesting that patients that have a better visual acuity before surgery are more demanding regarding visual outcomes after surgery.

In vitro and schematic model eye assessment of glare or positive dysphotopsia-type photic phenomena: Comparison of a new material IOL to other monofocal IOLs

PURPOSE

To compare the glare-type photic phenomena for a new intraocular lens (IOL) to other monofocal IOLs, and to investigate how IOL design features might affect these phenomena.

SETTING

Alcon Laboratories, Inc., Fort Worth, Texas; John A Moran Eye Center, University of Utah, Salt Lake City, USA.

DESIGN

Schematic model eye evaluation and in vitro study.

METHODS

Five monofocal IOL models (Clareon CNA0T0, Tecnis ZCB00, enVista MX60, Eternity W-60, and Vivinex XY1) were used to evaluate glare or positive dysphotopsia-type phenomena. Optical simulations of incoming light were generated using nonsequential ray-tracing software based on a collimated light source for various off-axis angles of illumination. The simulation analyses were verified using a laboratory in vitro bench-top glare measurement system.

RESULTS

The Clareon and Vivinex IOLs produced focused off-axis images with negligible peripheral glare characteristics. The Tecnis and enVista IOLs produced dispersed images with additional glare characteristics at 45 degrees of off-axis illumination and higher. The Eternity IOL showed the highest edge-reflected glare characteristic, likely because of its straight optic edge geometry. The laboratory bench images and glare intensity profiles were consistent with the simulation data.

CONCLUSIONS

In vitro and nonsequential ray-tracing evaluations showed that straight optic edges and peripheral nonimaging optic geometry might contribute to positive dysphotopsia. The IOL designs with optic edge curvature and full functional optics demonstrated the lowest level of glare-type photic phenomena. Only clinical studies can confirm whether the differences observed between the IOLs in vitro are clinically significant.

Paradigm shifts, peregrinations and pixies in ophthalmology

Human ingenuity is challenged by defending vision, our highest bandwidth sense. Special challenges are presented by the replacement or repair of highly specialized but scarce tissue within the constraints of transparency, tissue shape and alignment, tissue borders and pressure maintenance. Many, mostly destructive, surgical procedures were developed prior to an understanding of underlying pathophysiology. For a number of conditions, both reconstructive and destructive procedures co-exist, yet there are few guidelines as to the better approach. Because the consequences of these procedures may take many years to surface (consistent with a stem cell role in long-term tissue maintenance), guidance may be provided by the elucidation of underlying principles from these approaches. Illustrative examples from clinical, basic research and biotechnology, particularly relating to pterygium, ocular surface squamous neoplasia, dry-eye syndrome, corneal rehabilitation and replacement, cataract surgery, strabismus surgery and bionic eye research, are described. An unexpected consequence of bionic device development has been an appreciation of the sophistication of tissues being replaced, given the limitations of available biomaterials. Examples of how this has provided insights into ocular disease will be illustrated. Stem cell and biomaterial technologies are starting to impact at a time when cost-effectiveness is under scrutiny. Both efficacy and cost will need to be considered as these interventions are introduced. It appears that the paradigm shift rate is accelerating and there is evidence of this in ophthalmology. Lessons learned from the areas of destructive versus reconstructive surgery and the limitations of development of bionic replacements will be used to illustrate how new procedures and technologies can be developed.

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.

Range of refractive independence and mechanism of action of a corneal shape-changing hydrogel inlay: results and theory

PURPOSE

To demonstrate the independence of visual performance over a range of preoperative refraction and age in presbyopes implanted with a corneal shape-changing inlay (Raindrop Near Vision Inlay).

SETTING

Two multispecialty clinics, Monterrey and Tijuana, Mexico.

DESIGN

Prospective case series.

METHODS

The nondominant eyes of patients were implanted with the hydrogel corneal inlay beneath a femtosecond flap, centered on the pupil. Clinical outcomes included uncorrected near, intermediate, and distance visual acuity (UNVA, UIVA, and UDVA) and patient-assessed task performance in good light and dim light. Statistical analyses assessed the dependencies on preoperative age (45 to 60 years) and preoperative manifest refraction spherical equivalent (MRSE) (-0.5 to +1.5 diopters [D]). Using the inlay effect derived from wavefront measurements, an eye model was created through which letter charts were simulated.

RESULTS

The study evaluated eyes of 188 patients. Postoperative UNVA, UIVA, and task performance at these distances in good light was independent of age and preoperative MRSE (P > .05). Postoperative UDVA was weakly dependent on preoperative MRSE, but distance task performance in good light was not (P > .05). In the treated eye, the mean postoperative UNVA was 20/25, UIVA was 20/25, and UDVA was 20/32. The clinical outcomes are explained by consideration of zones within the pupil generating good near, intermediate, and distance image quality. This was confirmed by visual acuity simulations.

CONCLUSIONS

The continuous center-near power profile induced by the corneal shape-changing inlay provides good visual acuity and performance from distance through near over a 2.0 D range of preoperative refraction and presbyopic age.

FINANCIAL DISCLOSURE

Drs. Steinert, Schwiegerling, Barragán-Garza, and Chayet are consultants to Revision Optics, Inc. Drs. Lang and Holliday and Mr. Roy are employees of Revision Optics, Inc. Drs. Steinert, Schwiegerling, Barragán-Garza, and Chayet have no financial or proprietary interest in any material or method mentioned.

Refractive index and its impact on pseudophakic dysphotopsia

Purpose

It has been shown that the biggest dissatisfier for uncomplicated cataract surgery patients is pseudophakic dysphotopsia (PD). While edge design of an intraocular lens (IOL) impacts this problem, refractive index is still controversial as to its impact. This retrospective cohort study was designed to determine the role of increasing refractive index in PD.

Patients and methods

This study was conducted at the John A. Moran Eye Center, University of Utah, USA. A retrospective chart review identified patients who received one of two hydrophobic acrylic single piece IOLs (AcrySof WF SP [SN60WF] or Tecnis SP [ZCB00]), which differed mainly by refractive index (1.55 versus 1.47). Eighty-seven patients who had received implantation of a one-piece hydrophobic acrylic IOL were enrolled. Patients were included if the surgery had been uncomplicated and took place at least a year before study participation. All eligible patients had 20/20 best corrected vision, without any disease known to impact visual quality. In addition to conducting a record review, the enrolled patients were surveyed for PD, using a modified National Eye Institute Visual Function questionnaire, as well as for overall satisfaction with visual quality.

Results

Statistical analysis demonstrated no difference between the two cohorts regarding PD, general visual function, and overall visual satisfaction.

Conclusion

The study suggests that with the two IOLs assessed, increasing the refractive index does not increase incidence of PD or decrease overall visual satisfaction.

Clinical outcomes with a new trifocal intraocular lens

PURPOSE

To evaluate visual and refractive outcomes, contrast sensitivity, and quality of vision after cataract surgery with the implantation of a new modality of trifocal intraocular lens (IOL).

METHODS

This case series comprised 30 patients who had bilateral implantation of the AT.LISA tri 839 MP trifocal IOL after phacoemulsification for either cataract or refractive lens exchange surgery. Uncorrected (UDVA) and corrected monocular distance visual acuity (CDVA) using a logMAR chart, binocular uncorrected (UNVA) and corrected near visual acuity (CNVA) (40 cm and patients' preferred distance) using the Radner Reading Charts, distance-corrected intermediate visual acuity (DCIVA) (70 cm), a binocular defocus curve, contrast sensitivity (CS) with the Pelli-Robson test, and subjective quality of vision by a short questionnaire were evaluated at 1, 3, and 6 months postoperatively.

RESULTS

At 6 months, mean values of 0.05 ± 0.07 and -0.02 ± 0.05 logMAR were obtained for monocular UDVA and CDVA, respectively. Mean values of 0.16 ± 0.07, 0.12 ± 0.07, and 0.16 ± 0.07 logRAD were obtained for binocular UNVA, CNVA, and DCIVA, respectively. Significant changes were only detected in monocular CDVA (p<0.01) and UDVA that improved between 3 and 6 months postoperatively (p = 0.01). A visual acuity level of 0.2 logRAD could be seen in binocular defocus curves between +1.00 and -3.00 D. At 6 months, mean photopic and mesopic CS were 1.52 ± 0.11 and 1.54 ± 0.11. Regarding the questionnaire, almost all patients were satisfied with their distance, intermediate, and near vision. Difficulties associated with photic phenomena decreased significantly over time.

CONCLUSIONS

The AT.LISA trifocal IOL provides excellent uncorrected distance, intermediate, and near visual outcomes.

IOL with square-edged optic and reduced dysphotopsia

PURPOSE

To demonstrate a new optic edge design that preserves advantages of the square-edged optic and substantially reduces intensity of the light pattern formed at the retina by internal reflection off the optic edge.

METHODS

Non-sequential ray tracing (Zemax optical design software) was used to model light intensity and distribution of the light pattern at the retina formed by internal light reflection off different optic edges in intraocular lens of otherwise equivalent configurations.

RESULTS

A maximum intensity of the light pattern formed by internal reflection off the optic edge occurs within 35 to 42.5° of the field angle. An undulated square-edged optic reduces the maximum light intensity of the light pattern formed at the retina by a factor of 5, when compared with a conventional double square-edged optic.

CONCLUSIONS

Edge undulation of the square-edged optic is an effective addition to intraocular lens designs that reduces the potential for dysphotopsia caused by the optic edge internal reflection of light.