Ophthalmic Surgery, Lasers and Imaging Retina

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Case Report 

Concentric Ring Scanning Laser Ophthalmoscope Artifacts and Dysphotopsia in Diffractive Multifocal Pseudophakia

Jeffrey K. Luttrull, MD; Paul J. Dougherty, MD; Huawei Zhao, PhD; Martin A. Mainster, PhD, MD, FRCOphth

Abstract

A 67-year-old woman had decreased visual acuity in her left eye and disturbing concentric ring dysphotopsias after bilateral implantation of ReSTOR (SN60D3; Alcon Laboratories, Inc., Fort Worth, TX) diffractive multifocal intraocular lenses (IOLs). Monochromatic (820-nm infrared and 488-nm red-free) scanning laser ophthalmoscopy (SLO) documented central retinal concentric ring patterns resembling the patient’s drawings of her dysphotopsia, prompting investigation of the relationship of these phenomena. Similar SLO findings were present in four eyes of three additional ReSTOR pseudophakes without dysphotopsia, but absent in monofocal pseudophakes or phakic individuals. Optical analysis shows that concentric ring SLO imaging artifacts can be caused by coherent reflection of monochromatic laser radiation off the diffractive optical element on the IOL’s anterior surface, whereas concentric ring dysphotopsias are due to diffraction or projection of broad spectrum light sources in ordinary environments. Thus, the IOL’s diffractive optics is the origin of both concentric ring dysphotopsia and SLO artifacts, but diffraction or projection causes the visual phenomenon, whereas coherent reflection produces the imaging anomaly.

Abstract

A 67-year-old woman had decreased visual acuity in her left eye and disturbing concentric ring dysphotopsias after bilateral implantation of ReSTOR (SN60D3; Alcon Laboratories, Inc., Fort Worth, TX) diffractive multifocal intraocular lenses (IOLs). Monochromatic (820-nm infrared and 488-nm red-free) scanning laser ophthalmoscopy (SLO) documented central retinal concentric ring patterns resembling the patient’s drawings of her dysphotopsia, prompting investigation of the relationship of these phenomena. Similar SLO findings were present in four eyes of three additional ReSTOR pseudophakes without dysphotopsia, but absent in monofocal pseudophakes or phakic individuals. Optical analysis shows that concentric ring SLO imaging artifacts can be caused by coherent reflection of monochromatic laser radiation off the diffractive optical element on the IOL’s anterior surface, whereas concentric ring dysphotopsias are due to diffraction or projection of broad spectrum light sources in ordinary environments. Thus, the IOL’s diffractive optics is the origin of both concentric ring dysphotopsia and SLO artifacts, but diffraction or projection causes the visual phenomenon, whereas coherent reflection produces the imaging anomaly.

Concentric Ring Scanning Laser Ophthalmoscope Artifacts and Dysphotopsia in Diffractive Multifocal Pseudophakia

From the Ventura County Retina Group (JKL), Ventura, California; Jules Stein Eye Institute (PJD), UCLA, Los Angeles, California; Dougherty Laser Vision (PJD), Los Angeles, California; Abbott Medical Optics, Inc. (HZ), Santa Ana, California; and the Department of Ophthalmology (MAM), University of Kansas School of Medicine, Prairie Village, Kansas.

Presented in part at the annual meeting of the European Society of Cataract and Refractive Surgery, September 14, 2009, Barcelona, Spain; and the Retina Congress, October 3, 2009, New York, New York.

Dr. Luttrull has no financial or proprietary interest in the materials presented herein. Dr. Dougherty is a consultant to Inspire, Nidek, Staar, Lenstec, and Bausch and Lomb Corporations. Dr. Zhao is an employee of Abbott Medical Optics, Inc. Dr. Mainster is a consultant to Abbott Medical Optics, Inc., IRIDEX, and Ocular Instruments Corporations.

Address correspondence to Martin A. Mainster, PhD, MD, Department of Ophthalmology, University of Kansas School of Medicine, 7400 State Line Road, Prairie Village, KS 66208-3444. E-mail: martin.mainster@att.net

Received: January 20, 2010
Accepted: July 26, 2010
Posted Online: September 29, 2010

Introduction

Most multifocal pseudophakes are pleased with their uncorrected near and distance visual acuity, but a small percentage of them report annoying halos, glare, and dysphotopsia.1–3 Photic phenomena in monofocal and multifocal pseudophakes have many forms,4 but persistent concentric ring dysphotopsia is uncommon. Haze, crescents, and circular artifacts occur in conventional fundus photography5 and saccades can cause aliasing artifacts in scanning laser ophthalmoscopy (SLO),6 but concentric ring artifacts are not characteristic of either fundus camera or SLO autofluorescence or angiographic images. Concentric ring artifacts occurred in monochromatic SLO images of a diffractive multifocal pseudophakic patient who complained of decreased vision in her left eye associated with persistent concentric ring dysphotopsia.

Case Report

A 67-year-old woman had undergone laser treatment for a peripheral retinal tear in her left eye in 1995. Her best-corrected visual acuity (BCVA) was 20/20 in her left eye before and after retinal photocoagulation in 1995. She had no postoperative visual complaints. In February 2006, her BCVA was 20/25 in her right eye and 20/30 in her left eye, respectively. Corneal power and axial length were 45.9/45.8 and 26.12 in her right eye and 45.9/45.6 and 25.68 in her left eye. She underwent refractive lensectomy with implantation of a ReSTOR (SN60D3; Alcon Laboratories, Inc., Fort Worth, TX) diffractive multifocal intraocular lens (IOL) in each eye. Her BCVA postoperatively was 20/25 in her right eye and 20/30 in her left eye. Postoperative refraction was −0.75 + 0.75 × 10 in her right eye and −0.5 + 0.75 × 180 in her left eye. She was disturbed by concentric ring dysphotopsias in both eyes, most prominent during driving and in twilight situations.

Bilateral Nd:YAG laser posterior capsulotomies failed to improve the patient’s symptoms and she was referred for retinal evaluation in January 2007. At that time, her BCVA was 20/25 in her right eye and 20/30 in her left eye. Her ophthalmic examination was within normal limits except for a well-centered ReSTOR IOL and capsulotomy in each eye and photocoagulation scars peripherally in her left retina. Time-domain optical coherence tomography and fluorescein angiography were normal at that time. In June 2007, macular epiretinal membrane formation reduced the BCVA in her left eye to 20/40. Her BCVA returned to 20/30 after removal of the epiretinal membrane.

The patient continued to complain of concentric ring dysphotopsia and decreased vision in both eyes and was reevaluated in December 2008. Figure 1 is the patient’s sketch of her dysphotopsia at the time. BCVA remained 20/25 in her right eye and 20/30 in her left eye. Spectral-domain optical coherence tomography (Spectralis; Heidelberg Engineering, Inc., Heidelberg, Germany) and fluorescein angiography were normal, but monochromatic infrared (820-nm) and red-free (488-nm) SLO images documented central retinal concentric ring patterns resembling the patient’s sketches of her dysphotopsia. Figure 2 shows infrared SLO images of the patient’s eyes.

The Patient’s Sketch of Her Persistent Concentric Ring Dysphotopsia.

Figure 1. The Patient’s Sketch of Her Persistent Concentric Ring Dysphotopsia.

Monochromatic Infrared (820-nm) 30° Scanning Laser Ophthalmoscope Images Show a Prominent Concentric Ring Artifact Centrally in the Patient’s (A) Right and (B) Left Retinas. The Diffractive Optical Element on the Anterior Surface of the ReSTOR Intraocular Lens (SN60D3; Alcon Laboratories, Inc., Fort Worth, TX) is the Origin for (1) the Scanning Laser Ophthalmoscope Artifact Caused by Optical Interference and (2) the Patient’s Dysphotopsia Caused by Optical Projection or Diffraction.

Figure 2. Monochromatic Infrared (820-nm) 30° Scanning Laser Ophthalmoscope Images Show a Prominent Concentric Ring Artifact Centrally in the Patient’s (A) Right and (B) Left Retinas. The Diffractive Optical Element on the Anterior Surface of the ReSTOR Intraocular Lens (SN60D3; Alcon Laboratories, Inc., Fort Worth, TX) is the Origin for (1) the Scanning Laser Ophthalmoscope Artifact Caused by Optical Interference and (2) the Patient’s Dysphotopsia Caused by Optical Projection or Diffraction.

Concentric ring artifacts were present in subsequent SLO studies of four eyes of three additional patients with ReSTOR IOLs. None of them reported dysphotopsia, even though they shared some of our patient’s biometric findings.

Discussion

We used the Piers-Norrby-Mester eye-model7 and ZEMAX optical analysis software (ZEMAX Development Corporation, Bellevue, WA) to simulate primary and undesired secondary (ghost) images in different functional light environments, substituting the patient’s corneal and axial length biometry for eye-model parameters. Details of this methodology have been published previously.8

Concentric ring artifacts in monochromatic SLO images can occur because of the optical interference of laser light reflected coherently off the concentric rings of the diffractive optical element on the front surface of the ReSTOR IOL. These artifacts are not present in broader spectrum color or angiographic imaging. They are most prominent in longer axial length pseudophakes such as our patient who have lower power IOLs with flatter anterior surfaces.

Concentric ring pseudophakic dysphotopsias are caused by diffraction or projection of broad spectrum illumination sources in normal environments. Dysphotopsia from diffraction is more likely to occur with smaller pupil diameters and parallel (distant) light sources, as our patient experienced in driving situations. It can also happen when light focused in the pupillary plane (Maxwellian view) projects an image of the IOL’s anterior surface diffractive optical element onto the retina. Surface reflections are more prominent with higher index of refraction, high chromatic dispersion optic materials as in our patient.9,10

The diffractive optical element on the anterior surface of a ReSTOR IOL originates concentric ring SLO artifacts caused by optical interference and dysphotopsia caused by optical projection or diffraction. The SLO artifacts are present in ReSTOR IOL pseudophakes with and without persistent concentric ring dysphotopsia. Thus, the artifacts can help identify the origin but cannot predict the presence of this photic phenomenon, which depends on numerous other factors, including neural plasticity.11

References

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  11. Mainster MA, Turner PL. Multifocal IOLs and maculopathy. In: Chang DF, ed. Mastering Refractive IOLs: the Art and Science. Thorofare, NJ: SLACK Incorporated; 2008:389–394.
Authors

From the Ventura County Retina Group (JKL), Ventura, California; Jules Stein Eye Institute (PJD), UCLA, Los Angeles, California; Dougherty Laser Vision (PJD), Los Angeles, California; Abbott Medical Optics, Inc. (HZ), Santa Ana, California; and the Department of Ophthalmology (MAM), University of Kansas School of Medicine, Prairie Village, Kansas.

Presented in part at the annual meeting of the European Society of Cataract and Refractive Surgery, September 14, 2009, Barcelona, Spain; and the Retina Congress, October 3, 2009, New York, New York.

Dr. Luttrull has no financial or proprietary interest in the materials presented herein. Dr. Dougherty is a consultant to Inspire, Nidek, Staar, Lenstec, and Bausch and Lomb Corporations. Dr. Zhao is an employee of Abbott Medical Optics, Inc. Dr. Mainster is a consultant to Abbott Medical Optics, Inc., IRIDEX, and Ocular Instruments Corporations.

Address correspondence to Martin A. Mainster, PhD, MD, Department of Ophthalmology, University of Kansas School of Medicine, 7400 State Line Road, Prairie Village, KS 66208-3444. E-mail: martin.mainster@att.net

10.3928/15428877-20100929-11

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