EyeWorld Asia-Pacific December 2015 Issue

49 EWAP REFRACTIVE December 2015 Views from Asia-Pacific Myoung Joon KIM, MD Asan Medical Center 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, South Korea Tel. no. +82-2-3010-3975 Fax no. +82-32-470-6440 Mjmjkim@gmail.com Sri GANESH, MD Chairman & MD, Nethradhama Super Speciality Eye Hospital 256/14, Kanakapura Main Road, 7th Block Jayanagar, Bangalore 560070, India Tel. no. +91-80-26088000 Fax no. +91-80-26633770 Chairman@nethradhama.org M ultifocal IOLs are definitely less forgiving than monofocal IOLs. I say three important tips for optical success in multifocal IOL implantation as A-B-C, which stands for astigmatism control, biometry, and cornea including tear film. Remnant refractive error after cataract surgery with multifocal IOLs is an important factor for dissatisfaction of patients. Wearing spectacles are the easiest and safest way if the patients agree. However, most patients who choose MIOLs in cataract surgery expect their best visual acuity to be regained without glasses. Residual astigmatism comes from various factors and may be associated with astigmatism of posterior corneal surface. LRI can be a good option in some cases. For significant spherical errors, IOL exchange or add-on lens implantation can be treatment options. Explanting IOL out of a capsular bag can be challenging after capsular adhesion and contraction. Viscodissection helps in such cases. There may be cost issues in using add-on lenses. LASIK causes less pain and provides faster recovery of vision than PRK. In my experience, postoperative pain could be well controlled by preemptive analgesia using topical NSAIDs. Vision recovery time could be improved by proper dry eye treatments. Laser refractive surgeries are highly effective in most cases, but not in hyperopia cases with steeper corneas. We have to make steep corneas steeper, which results in tear film instability and poor visual outcome. There is another issue when doing laser refractive surgery in eyes with multifocal IOLs. Hartmann–Shack sensors are not designed to capture the scattering incurred by the discrete junctions between the diffractive zones, and looking at the wavefront error only may lead to significant overestimation of the optical quality of eyes with DMIOLs. 1 When a surgeon wants to do wavefront-guided surgery in an eye with multifocal IOL, he or she has to be aware of possible measurement errors of wavefront sensors. Reference 1. Gatinel D. Limited accuracy of Hartmann-Shack wavefront sensing in eyes with diffractive multifocal IOLs. J Cataract Refract Surg . 2008;34:528; author reply 528-529. Editors’ note: Dr. Kim declared no relevant financial interests. T his article highlights the use of an excimer laser and surface ablation for residual refractive errors after multifocal IOLs. Multifocal IOLs are used during cataract surgery to provide spectacle-free vision to patients and residual refractive errors of more than 0.5 D spherical equivalent may be one of the reasons for dissatisfaction. Meticulous preoperative planning including non-contact biometry and appropriate IOL formula and applying a personalized surgeon’s constant will reduce postoperative refractive errors significantly. Mild residual errors can be treated with either LASIK or surface ablation. LASIK needs higher degree of skill and also has associated flap-related complications, hence PRK may be a better choice for cataract surgeons who want to enhance their multifocal results and who do not perform refractive surgery routinely. There are a few points to be kept in mind before performing an enhancement with surface ablation: 1. Wait for 3–6 months for the refraction to stabilize as capsular bag shrinkage could cause change in effective lens position and refraction. 2. Dry eye is common in the older cataract population and dry eye evaluation is mandatory before performing surface ablation. 3. These patients have to be warned about dry eye and prolonged use of lubricants. 4. Regression after surface ablation for lower degrees of refractive error in the older population may not be very significant and mitomycin C has to be used judiciously. 5. Patient’s symptoms have to be evaluated in detail to assess if the symptoms are due to the residual refractive error and a trail of glasses is advised before performing surface ablation. Transepithelial PRK and alcohol-assisted PRK are very easy to perform and effective techniques to correct lower refractive errors with high safety margins even for novice surgeons. Higher residual refractive errors may have to be corrected with an IOL exchange or a sulcus piggyback IOL. Editors’ note: Dr. Sri Ganesh is a consultant for Abbott Medical Optics and Carl Zeiss Meditec (Jena, Germany). epi-LASIK. Of these, alcohol removal is highly reliable without requiring specialized instruments or equipment. In summary, in this large sample of 602 patients who underwent PRK following multifocal IOL implantation, a significant reduction in sphere and cylinder was achieved with good refractive predictability. Uncorrected distance vision improved with no mean change in best corrected acuity. PRK is an effective procedure for the correction of low refractive errors after multifocal IOL surgery and one that is easy for cataract surgeons to learn. EWAP Editors’ note: Dr. Schallhorn is global medical director of Optical Express and professor of ophthalmology at the University of California San Francisco. He has financial interests with Abbott Medical Optics and Carl Zeiss Meditec (Jena, Germany). Contact information Schallhorn: scschallhorn@yahoo.com