EyeWorld Asia-Pacific March 2012 Issue

34 EW CATARACT/IOL March 2012 FAM Han Bor, MD Senior Consultant Tan Tock Seng Hospital 11 Jalan Tan Tock Seng, Singapore 308433 Tel. no. +65-63577726 Fax no. +65-63577718 famhb@singnet.com.sg N egative dysphotopsia is a bothersome phenomenon following successful modern cataract surgery. It is described as a crescent of shadow on the supero- temporal aspect of vision. The prevalence of negative dysphotopsia ranges from 0.16% to 15.2%. 1-3 It is more commonly associated with square-edged acrylic IOLs. 2 However, it has also been reported in round-edged silicone IOLs. 5 It occurs in perfectly done surgery with a well-centred IOL placed in the capsular bag with good overlapping anterior capsule. 5 There are two types of negative dysphotopsia: incisional 1 and IOL-related 1,4,5 . The incisional type occurs soon after a temporal clear cornea cataract surgery. This is a shadow from incisional corneal edema. The phenomenon disappears once the edema subsides. The IOL-related type lasts for months to years. The exact mechanism for this phenomenon is still elusive. Many hypotheses have been postulated. A likely explanation is that the square-edge reflects incoming temporal light rays, thus casting a shadow on the nasal retina. Newer analysis suggests that the dysphotopsia may be a complication of the anterior capsule and the in-the-bag IOL. 5 It is possibly due to a combination of IOL design, ocular anatomy and the lighting environment. My own personal experience is that the phenomenon is more common among square- edged IOLs; more common in acrylic than non-acrylic lenses. Active women are more likely to experience it than men. Most patients were able to cope with their activities and were not too bothered by it. Others found the phenomenon disabling and required surgical intervention. Preventive maneuvers such as placing the IOLs with its haptics at 3 and 9 o’clock have been suggested. Placing the haptics in such a manner is presumed to reduce the effect of the square edge. In the same vein, rotating the IOLs to the horizontal position has also been suggested as a treatment. For more definite treatment, a piggyback IOL in the sulcus works well. 4,5 It also provides another opportunity to correct whatever residual refractive errors the patient might have. IOL exchange with a round-edged silicone IOL placed in the sulcus is another option. Reverse optic capture is another novel way of overcoming this phenomenon. After more than a decade, negative dysphotopsia is still a challenge. References 1. Osher RH. Negative dysphotopsia: long-term study and possible explanation for transient symptoms. J Cataract Refract Surg . 2008;34:1699–1707. 2. Davison JA. Positive and negative dysphotopsia in patients with acrylic intraocular lenses. J Cataract Refract Surg . 2000;26:1346–1355. 3. Tester R, Pace NL, Samore M, Olson RJ. Dysphotopsia in phakic and pseudophakic patients: incidence in relation to intraocular lens type. J Cataract Refract Surg . 2000;26:810–816. 4. Vamosi P, Cs_ak_any B, N_emeth J. Intraocular lens exchange in patients with negative dysphotopsia symptoms. J Cataract Refract Surg . 2010;36:418–424. 5. Masket S, Fram NR. Pseudophakic negative dysphotopsia: Surgical management and new theory of etiology. J Cataract Refract Surg . 2011;37:1199–1207. Editors’ note: Dr. Fam is a consultant for Alcon, Abbott Medical Optics (Santa Ana, Calif., USA), and Zeiss (Jena, Germany), but has no financial interests related to his comments. Views from Asia-Pacific Myoung Joon KIM, MD Associate professor, Asan Medical Center 88 Olympic-ro 43-gil, Songpa-gu, Seoul, Republic of Korea Tel. no. +82-2-3010-3975 Fax no. +82-2-470-6440 mjmjkim@gmail.com R ecently, cataract surgery has been performed on patients with lower grades of cataract. The decision to do the surgery is made upon various visual symptoms and objective findings such as optical aberrations and scattering. It is true that traditionally a high contrast vision chart may not reflect degradation of visual performance. Therefore, patients’ expectations are growing. When cataract surgery was performed only for severe cataracts, the postoperative photic phenomenon or dysphotopsia was not an issue. Nowadays, dysphotopsia has been drawing more attention from cataract surgeons. Negative dysphotopsia is less tolerable to the postoperative patients than positive ones. In Korea, there are no case reports or prevalence reports of negative dysphotopsia. However, in my cases, there have been patients who complained of seeing a dark shadow that appeared similar to scotoma in the temporal field of vision. Fortunately, most patients’ symptoms resolved themselves over time without further surgical treatment. Increasing opacification between the anterior and posterior capsule seems to decrease the symptoms of negative dysphotopsia. I have never had the experience where surgical treatment was required due to the persistence of the symptoms of negative dysphotopsia. Intraocular lenses (IOLs) have been improved in terms of optical design and material. The square edge is a design for the prevention of posterior capsular opacification. With high refractive index materials, thinner IOLs can be made. This feature allows IOLs to be implanted through smaller incisions. Paradoxically, these improvements are related with negative dysphotopsia. If I come across a case with sustained negative dysphotopsia, I would recommend glasses first and wait and see for 6 to 12 months postoperatively and then proceed with surgical intervention. My first option would be to exchange the IOL. The new IOL would be round-edged and implanted into the ciliary sulcus. Currently, we don’t have proper testing methods which are widely used for dysphotopsia. Once we get standardized tests for dysphotopsia, we will be able to elucidate causes of dysphotopsia and provide information for better IOL design in this era of high expectations. Editors’ note: Prof. Kim has no financial interest related to his comments.