Objective evaluation of negative dysphotopsia with Goldmann kinetic perimetry

Peripheral Vision in Patients Following Intraocular Lens Implantation: A Systematic Review and Meta-Analysis

PURPOSE

To update the literature on peripheral optics and vision following intraocular lens (IOLs) implantation.

METHODS

We investigated how current IOLs influence peripheral visual function, peripheral optical quality, and visual perception and performance, in patients following cataract surgery. Peripheral vision is described as vision outside the central foveal region of the eye (beyond 4-5° of eccentricity). We systematically searched PubMed, Cochrane Central Register of Controlled Trials, Embase, and gray literature for relevant references. Randomized controlled trials and observational studies were eligible for inclusion. Finally, 47 studies with a total of 5963 participants were eligible for this review, of which 15 were included in the meta-analysis.

RESULTS

Regarding visual fields, the meta-analysis showed that the pooled estimate of mean deviation (MD) measured with perimetry tests (standard automated perimetry [SAP], short-wavelength automated perimetry [SWAP], and frequency doubling technology [FDT]) appears to be lower than the mean of healthy age-matched controls, regardless of IOL design. Results for pooled estimate show that localized defects (pattern standard deviation [PSD]) were higher than those in the healthy age-matched controls for FDT. We also collected evidence demonstrating that pseudophakia increases peripheral astigmatism and a myopic shift from 20° onward, leading to decreased peripheral image quality compared with that in phakic eyes. Patient-reported outcomes on peripheral vision showed a pooled score estimate of 95.19, indicating high satisfaction, and for the Steps & Stairs questions, a pooled score estimate at 0.23, indicating no to little difficulty seeing steps and stairs.

CONCLUSIONS

Peripheral image quality is degraded in eyes after cataract surgery. Nevertheless, whether this degradation leads to impaired visual function in the periphery requires further investigation.

Evaluation of a new device to treat negative dysphotopsia

PURPOSE

To evaluate the efficacy and safety of Negative Dysphotopsia (ND) Ring implantation for treating and preventing ND.

SETTING

Multicentric tertiary eye hospitals.

DESIGN

Prospective interventional cohort study.

METHODS

22 patients with ND were enrolled. Eyes with other ocular structural pathologies (corneal, macular, optic nerve head, retinal, neuro-ophthalmological) were excluded. In 15 eyes, the ring was implanted to treat ND (therapeutic group), and in 7 eyes, it was implanted during cataract surgery of the fellow eye as a prophylactic measure (prophylactic group) to prevent the occurrence of ND. Preoperative evaluation included video recording of the patients' complaints aside complete eye examination. Postoperatively, patients were interviewed to confirm resolution of complaints related to ND. The intraoperative difficulties and postoperative adverse events were recorded. A minimum follow-up of 1 year was completed for all eyes.

RESULTS

In the therapeutic group, 14 of 15 eyes (93.3%) patients reported complete resolution of ND on the first postoperative day while 1 patient reported persistence of a smaller and lighter temporal shadow. No ND was reported by any patient in any of the 7 eyes treated prophylactically. No significant adverse intraoperative event was recorded; however, vitreous upthrust was noted in 2 of 22 eyes (9.0%). No permanent drop in visual acuity was recorded in the therapeutic group.

CONCLUSIONS

ND Ring implantation was an easy, safe, and effective approach for both treating and preventing ND.

Peripheral visual field shifts after intraocular lens implantation

PURPOSE

To assess whether intraocular lens (IOL) implantation induces shifts in the peripheral visual field.

SETTING

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

DESIGN

Ray-tracing study.

METHODS

Nonsequential ray-tracing simulations were performed with phakic and pseudophakic versions of the same eye model to assess potential shifts in the visual field after IOL implantation. 2 different IOL designs were evaluated and for each design 5 different axial positions and 7 different intrinsic powers were tested. The relation between the physical position of the light source and the location where the retina was illuminated was determined for each eye model. Subsequently, these relations were used to calculate whether the visual field shifts in pseudophakic eyes.

RESULTS

The pseudophakic visual field shift was below 1 degree for central vision in all evaluated models. For peripheral vision, the light rays in the pseudophakic eyes were refracted to a more central retinal location compared with phakic eyes, resulting in a central shift of the peripheral visual field. The magnitude of the shift depended on the IOL design and its axial position, but could be as high as 5.4 degrees towards central vision.

CONCLUSIONS

IOL implantation tends to have little effect on the central visual field but can induce an over 5 degrees shift in the peripheral visual field. Such a shift can affect the perception of peripheral visual complaints.

Optical modeling of the entire visual field of the eye

Vision is rarely evaluated scientifically at very large visual angles, despite being used continuously in everyday life. Furthermore, raytrace calculations indicate that peripheral optical properties are different for a pseudophakic eye, and even though this is rarely noted by patients, it is probably the cause of bothersome "negative dysphotopsia." Simplified paraxial parameters that characterize the basic properties of phakic and pseudophakic eyes are collected together here as a baseline, and then raytracing is used to show that input angles of about 60°, which correspond to obstruction by the nose, eyebrow, and cheek, illuminate a retinal hemisphere. At larger angles in the temporal direction, the image with an intraocular lens (IOL) reaches a limit due to vignetting at about a 90° input angle to the optical axis, in comparison to 105° with the Gullstrand-Emsley eye model, and 109° for the most realistic gradient index crystalline lens model. Scaling the far peripheral vision region more accurately may lead to benefits relating to intraocular lenses, diseases of the peripheral retina, widefield fundus images, and myopia prevention.

Supplementary Implantation of 1stQ AddOn® Sulcus-Fixated Intraocular Lens to Treat Negative Dysphotopsia: A Retrospective Case Series

Negative dysphotopsia (ND) refers to the subjective perception of an arc-shaped darkness or shadow in the temporal field of vision. This condition occurs after uneventful cataract surgery with an in-the-bag intraocular lens (IOL). To address this issue, supplementary implantation of conventional three-piece IOLs in the sulcus or dedicated supplementary Rayner Sulcoflex® IOL have been used successfully. The aim of this retrospective case series was to assess the effectiveness of resolving ND using a supplementary 1stQ AddOn® (Medicontur) IOL. The 1stQ AddOn® has a different design and optic size compared to the Rayner Sulcoflex®. Patients experiencing severe and persistent ND underwent supplementary implantation of the 1stQ AddOn® IOL. The primary outcome measure was the resolution of dysphotopsia. Nine eyes received the 1stQ AddOn® IOL, with complete symptom resolution observed in 6 eyes, partial improvement in 1 eye, and no change in 2 eyes. This indicates that supplementary implantation of the 1stQ AddOn® IOL can effectively and safely treat ND, performing equally well as the Rayner Sulcoflex®. The positive impact of sulcus-fixated supplementary IOLs seems to be related to the interaction between the central optic and the pupil margin.

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%.

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.

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.

Surgical management of positive dysphotopsia: U.S. perspective

PURPOSE

To evaluate clinical outcomes of intraocular lens (IOL) exchange for intolerable positive dysphotopsia (PD).

SETTING

Private practice, Advanced Vision Care, Los Angeles, California, USA.

DESIGN

Retrospective review, case series.

METHODS

Fifty-six eyes of 46 pseudophakic patients requiring surgical management of PD between 2013 and 2019 were reviewed. Thirty-seven eyes had PD alone and 19 had combined negative dysphotopsia and PD.

INCLUSION CRITERIA

corrected distance visual acuity of 20/30 or better without significant corneal, retinal, or optic nerve pathology.

EXCLUSION CRITERIA

corneal, macular, or optic nerve disease and multifocal dysphotopsia alone (defined patterns of concentric multiple halos or spider web patterns when looking at a point source of light). Primary outcome measure was improvement or resolution of self-reported PD symptoms by 3 months postoperatively. Secondary outcome measures included analysis of intraocular lenses (IOLs) that induced PD for IOL material, index of refraction, and edge design.

RESULTS

IOL materials successful in the alleviation of PD symptoms were as follows: 20 (87.8%) of 33 silicone, 15 (76.2%) of 21 copolymer, and 2 poly(methyl methacrylate) (100%). However, when considering IOL exchange for an acrylic to silicone optic or acrylic to collamer optic, the percentages of improvement are indistinguishable at 87% and 88%, respectively.

CONCLUSIONS

PD symptoms might be improved by changing the IOL material and, therefore, index of refraction. Although edge design plays an important role in etiology, changing the IOL material to a lower index of refraction may prove to be an effective surgical strategy to improve intolerable PD.

Scaling the Retinal Image of the Wide-Angle Eye Using the Nodal Point

Angles subtended at the second nodal point of the eye (NP2) are approximately the same as input visual angles over a very large angular range, despite the nodal point being a paraxial lens property. Raytracing using an average pseudophakic eye showed that the angular nodal point criterion was only valid up to about 10°, and that the linear relationship was due instead to the cornea and lens initially creating chief ray angles at the exit pupil that are about 0.83 times input values for this particular eye, and then by the retina curving around to meet the rays in a manner that compensates for increasing angle. This linear relationship is then also maintained when retinal intersections are calculated relative to other axial points, with angles rescaled approximately using the equation R/(R + delta), where delta is the axial distance from the center of a spherical retina of radius R. Angles at NP2 approximately match the input angles, but the terminology is misleading because this is not a paraxial property of the eye. Chief rays are used with finite raytracing to determine the actual behavior.

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.

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.