December 2020

ASCRS NEWS

EyeWorld Journal Club
Review of “Surgical management of positive dysphotopsia: U.S. perspective”


by Natacha Villegas, MD, Alejandro Arboleda, MD, MS, Malini Veerappan Pasricha, MD, and Jose Davila, MD


Suzann Pershing, MD

Ophthalmology Residency Program Director
Stanford University
Stanford, California








Stanford University ophthalmology residents Natacha Villegas, MD, Alejandro Arboleda, MD, MS, Malini Veerappan Pasricha, MD, Jose Davila, MD

Pseudophakic positive dysphotopsia can be just as bothersome as negative dysphotopsia. I invited the Stanford residents to review this large retrospective series of patients who were managed with IOL exchange.

—David F. Chang, MD,
EyeWorld Journal Club Editor

Cataract surgery is one of the most common surgeries performed annually and is only expected to increase in coming decades due to an aging population. Despite advances in surgical technique, which have significantly improved efficiency, patient safety, and predictability of cataract surgery refractive outcomes, postoperative visual disturbances such as dysphotopsias continue to be a significant contributor to patient dissatisfaction, even in routine cases performed by experienced surgeons.
Positive dysphotopsia (PD) was first reported by Masket et al. in 1993, as an undesirable optical phenomenon following cataract surgery described by patients as light streaks, bright arcs, and/or halos induced by external light.1 This visual phenomenon was attributed to scattering of light from the edge of ovoid intraocular lenses (IOL). Subsequent studies have suggested numerous factors can affect incidence of PD, including IOL characteristics, surgical technique, and ocular anatomy.2,3 Contributing IOL properties include a squared-edge design, high dioptric power, small radius of curvature, and lens refractive index.2
Overall, incidence of positive and negative dysphotopsia (ND, a temporal dark crescent- shaped or linear shadow) has been estimated at 49% in the immediate postoperative period, decreasing to 0.2–2.2% over 12 months postoperatively.2,4,5 This is generally thought to be an underestimation, as patients frequently will not report PD symptoms unless directly asked.6 Additionally, objective evaluation of PD remains elusive, due to a lack of tools to quantify its impact on visual function.
Management of PD remains challenging. Conservative management is considered first-line, including education, reassurance, and in some cases, pharmacologic miosis, which may reduce PD by decreasing the amount of light passing through the IOL. Treatment of refractive error and postoperative complications such as posterior capsule opacification can also reduce PD. If these measures fail, invasive procedures such as piggyback IOL implantation and IOL exchange may be considered.2 However, there is limited data on outcomes of surgical approaches to treat PD. In this retrospective case series, Masket and colleagues report outcomes of IOL exchange for PD.

Study summary

This is a non-randomized, retrospective review of 56 eyes from 46 patients who underwent surgical management of PD between 2013 and 2019. All patients had visual acuity of 20/30 or better as well as uncomplicated cataract surgery with a centered posterior chamber IOL (PC-IOL) and an unremarkable postoperative course other than PD symptoms. Included patients reported light arcs, light streaks, shimmering, flickering, halos, and non-concentric starbursts present for more than 1 month. Symptoms from entoptic causes, Maddox rod effect from striae in the posterior capsule, diffractive optic, and/or from multifocal dysphotopsias were not counted as true PD. Exclusion criteria included history of significant corneal, retinal, or optic nerve pathology, multifocal dysphotopsias, and refractive surgery with dysphotopsias. The most common inciting IOL material in this case series was hydrophobic acrylic (79%), followed by silicone (9%), hydrophilic acrylic (7%), and copolymer/hydrophilic (5%).
The primary study outcome was resolution or improvement of PD symptoms within 3 months after surgical intervention via IOL exchange. There were four surgical approaches to IOL exchange: (1) bag-to-bag PCIOL exchange for patients with isolated PD symptoms, (2) IOL exchange with reverse optic capture for patients with combined ND/PD, (3) bag-to-sulcus IOL exchange for patients with isolated PD symptoms with an open posterior capsule, and (4) bag-to-sulcus IOL exchange with iris suture fixation for patients with isolated PD or combined ND/PD with inadequate capsular support. In all instances, the initial IOL was exchanged for an IOL with a lower refractive index.
The majority of eyes experienced PD resolution after a single IOL exchange (85.7%, n=48). There were 8 cases of initial treatment failure; of these, 3 eyes had successful second IOL exchange. The remaining 5 patients declined additional surgery. No patients reported worsening symptoms after surgery. Relative success based on replacement IOL type could not be compared due to small sample size, however, the authors reported 100% success with PMMA IOLs (n=2), 87.8% with silicone (20/33), and 76.2% with copolymer (15/21). For PD from initial acrylic IOLs, exchanging with a silicone versus copolymer IOL yielded similar success rates (87% versus 88%).

Discussion

PD following modern cataract surgery can have a significant impact on vision and quality of life. Although surgical approaches for ND have been studied (including anterior IOL repositioning and reducing iris-IOL distance), there is a paucity of evidence on surgical approaches for PD refractory to medical therapy.7
This case series by Masket et al. retrospectively reviews 56 eyes treated with IOL exchange for PD. Remarkably, more than 85% of patients reported resolution of PD symptoms. IOL exchange may address three main etiologies for PD:
Square-edge design: Square-edge design is the greatest contributing factor to PD. Currently, all foldable IOLs in the United States have some square edge due to its association with reduced posterior capsule opacification.8 PMMA IOLs are available without square edges, however, practical utility is limited since they are rigid and inflexible, requiring large incisions. Further studies are needed to determine if specific square-edge designs may have lower incidence or intensity of PD.
IOL material and index of refraction: Higher index of refraction is associated with higher surface reflectivity and internal reflection, and therefore increased PD. Most of the patients in this study had hydrophobic acrylic IOLs replaced with non-acrylic IOLs. Replacing acrylic IOL with silicone or copolymer appeared equally successful.
IOL position: In previous work by Masket et al., ND was found primarily related to IOL position.9 The strategy to manage combined ND/PD in this study was thus bag-to-sulcus exchange or reverse optic capture.
The authors noted that the most successful single replacement IOL in their analysis was a square-edge 3-piece silicone L161AO (Bausch + Lomb), however, sample size was too small to draw firm statistical conclusions regarding relative superiority of one IOL type over another. Success of IOL exchange appeared to be driven by replacement with an IOL of lower refractive index. Among the 15% of patients who did not experience alleviation of PD after IOL exchange, factors such as smaller optic size and flatter anterior curvature may contribute via greater light reflection onto the retina.4,10 A secondary analysis of outcomes based on pupil size and IOL refractive power would provide useful information for preoperative discussions and decision-making.
Limitations of this study include its retrospective non-randomized design and constrained sample size for statistical comparisons among IOL types. Included patients volunteered their PD symptoms; there was no questionnaire to screen for PD, which is usually underreported,8 potentially introducing sampling bias. Findings may also be influenced by placebo effect, given the subjective nature of PD and lack of a control population. Finally, only two physicians performed IOL exchanges in this study, which places substantial weight on their specific surgical skills and may limit generalizability.
It is also important to consider that although reported success rates in this study are high, there are inherent risks to IOL exchange including capsular compromise, zonular dehiscence, endophthalmitis, and cystoid macular edema.11,12,13,14 Risk may be influenced by other ocular comorbidities, time since initial cataract surgery, extent of capsular fibrosis, and skill of the surgeon, and it is essential to have an informed discussion of risks and expected benefits weighed against severity of a patient’s symptoms.
Despite limitations, this study offers an important early step in understanding positive dysphotopsias, including contribution of IOL refractive index and square-edge IOL design and the potential role of IOL exchange. Its promising results prompt future studies of IOL exchange for PD, with larger sample size and a broader pool of surgeons to compare outcomes with specific replacement IOLs, IOL material, and surgical approaches, and to investigate incidence of complications. IOL exchange represents an important tool in the arsenal of ophthalmologists to address this challenging visual phenomenon that affects patients worldwide.

References

1. Masket S, et al. Undesired light images associated with ovoid intraocular lenses. J Cataract Refract Surg. 1993;19:690–694.
2. Hu J, et al. Dysphotopsia: a multifaceted optic phenomenon. Curr Opin Ophthalmol. 2018;29:61–68.
3. Masket S, Fram NR. Pseudophakic dysphotopsia: review of incidence, cause, and treatment of positive and negative dysphotopsia. Ophthalmology. 2020. Online ahead of print.
4. Davison JA. Positive and negative dysphotopsia in patients with acrylic intraocular lenses. J Cataract Refract Surg. 2000;26:1346–1355.
5. Ellis MF. Sharp-edged intraocular lens design as a cause of permanent glare. J Cataract Refract Surg. 2001;27:1061–1064.
6. Makhotkina NY, et al. Effect of active evaluation on the detection of negative dysphotopsia after sequential cataract surgery: discrepancy between incidences of unsolicited and solicited complaints. Acta Ophthalmol. 2018;96:81–87.
7. Vámosi P, et al. Intraocular lens exchange in patients with negative dysphotopsia symptoms. J Cataract Refract Surg. 2010;36:418–424.
8. Nishi O, et al. Preventing lens epithelial cell migration using intraocular lenses with sharp rectangular edges. J Cataract Refract Surg. 2000;26:1543–1549. References (cont.)
9. Masket S, et al. Surgical management of negative dysphotopsia. J Cataract Refract Surg. 2018;44:6–16.
10. Erie JC, et al. Analysis of postoperative glare and intraocular lens design. J Cataract Refract Surg. 2001;27:614–621.
11. Davies EC, Pineda R. Intraocular lens exchange surgery at a tertiary referral center: Indications, complications, and visual outcomes. J Cataract Refract Surg. 2016;42:1262–1267.
12. Jones JJ, et al. Indications and outcomes of intraocular lens exchange during a recent 5-year period. Am J Ophthalmol. 2014;157:154–162.e1.
13. Marques FF, et al. Longitudinal study of intraocular lens exchange. J Cataract Refract Surg. 2007;33:254–257.
14. Dagres E, et al. Perioperative complications of intraocular lens exchange in patients with opacified Aqua-Sense lenses. J Cataract Refract Surg. 2004;30:2569–2573.

Contact

Pershing: pershing@stanford.edu
 

Surgical management of positive dysphotopsia: U.S. perspective

Samuel Masket, MD, Zsofia Rupnick, MD, Nicole Fram, MD, Stephen Kwong, BS, Jessie McLachlan, BA
J Cataract Refract Surg. 2020;46(11):1474–1479.

Purpose: To evaluate clinical outcomes of IOL exchange for intolerable positive dysphotopsia (PD)
Setting: Private practice, Advanced Vision Care,
Los Angeles, California
Design: Retrospective review, case series
Methods: 56 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 (ND) and PD. Inclusion criteria: BCVA of 20/30 or better without significant corneal, retinal, or optic nerve pathology. Exclusion criteria: Corneal, macular, or optic nerve disease, 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 after surgery. Secondary outcome measures included analysis of IOLs that induced PD with regard to IOL material, index of refraction and edge design.
Results: IOL materials successful in the alleviation of PD symptoms were as follows: 20/33 silicone (87.8%), 15/21 copolymer (76.2%), and 2/2 PMMA (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.
Conclusion: PD symptoms may 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.

Review of “Surgical management of positive dysphotopsia: U.S. perspective” Review of “Surgical management of positive dysphotopsia: U.S. perspective”
Ophthalmology News - EyeWorld Magazine
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