Eyeworld

DECEMBER 2020 | EYEWORLD | 17 and reducing iris-IOL distance), there is a pau- city of evidence on surgical approaches for PD refractory to medical therapy. 7 This case series by Masket et al. retro- spectively 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. Fur- ther 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 reflec- tion, 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 regard- ing 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 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 resolu- tion or improvement of PD symptoms within 3 months after surgical intervention via IOL ex- change. 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 symp- toms with an open posterior capsule, and (4) bag-to-sulcus IOL exchange with iris suture fix- ation 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 resolu- tion 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 ex- change. The remaining 5 patients declined addi- tional 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 copo- lymer 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 continued on page 18 continued from page 14 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 phenom- enon. Curr Opin Ophthalmol. 2018;29:61–68. 3. Masket S, Fram NR. Pseu- dophakic dysphotopsia: review of incidence, cause, and treat- ment 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 intra- ocular 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 dyspho- topsia after sequential cataract surgery: discrepancy between incidences of unsolicited and solicited complaints. Acta Oph- thalmol. 2018;96:81–87. 7. Vámosi P, et al. Intraocular lens exchange in patients with negative dysphotopsia symp- toms. 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.

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