RADIAL KERATOTOMY with a SMALL OPTICAL ZONE What Are the Options for Reducing Refractive Error and Improving Distance Visual Acuity?
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REFRACTIVE SURGERY CASE FILES s RADIAL KERATOTOMY WITH A SMALL OPTICAL ZONE What are the options for reducing refractive error and improving distance visual acuity? BY KARL G. STONECIPHER, MD; H. BURKHARD DICK, MD, PHD, FEBOS-CR; MICHAEL MARINO, OD; AND ALEKSANDAR STOJANOVIC, MD, PHD Figure 1. Holladay Reports from the Pentacam (Oculus Optikgeräte) for the right and left eyes. Figure 2. RMS HOA data show the patient’s distorted corneas. CASE PRESENTATION A 66-year-old man presents with a desire to reduce his refractive error The slit-lamp examination is notable for RK using a small optical zone, and improve his distance visual acuity. The patient’s history is significant for with obvious decentration of the optical zone and irregular incisions. A Tecnis a Russian-style eight-incision radial keratotomy (RK) using a 2.75-mm optical 1-Piece IOL (model ZCBOO, Johnson & Johnson Vision) is well centered in each zone in 1992. eye. No retinal pathology is evident, and the patient has no systemic diseases. Upon examination, the corneas appear to be normal except for the RK. The posterior capsule of each eye is intact and clear (Figures 1 and 2). Manifest refractions are stable and do not fluctuate from morning to evening. How would you proceed? UCVA is 20/100 OD and 20/40 OS. BCVA is +1.25 +1.50 x 018º = 20/30 OD and +0.50 +0.25 x 115º = 20/25 OS. —Case prepared by Karl G. Stonecipher, MD MARCH 2020 | CATARACT & REFRACTIVE SURGERY TODAY 29 s REFRACTIVE SURGERY CASE FILES capsulotomy before implanting an along the incision scars. A scleral lens XtraFocus. I strongly recommend using creates a stable optical surface, which a cylindrical rod tip for insertion rather gives patients the best possible visual than a flat rod tip, which I have found acuity. Depending on the amount has a tendency to go under this very of residual astigmatism, multifocal H. BURKHARD DICK, MD, thin device. correction could be possible as well. PHD, FEBOS-CR Once in place, the XtraFocus does Another benefit of scleral lenses is their not prevent a thorough examination effectiveness at treating dry eye. This case is certainly a harbinger of of the posterior segment, but there Even when scleral contact lenses things to come. During the next few is a learning curve to the technique. I provide adequate visual acuity, patients years, we can expect to see a large should note that the XtraFocus, like such as this one may be bothered number of men and women who, in the IC-8, can achieve good outcomes more by glare than by reduced visual their younger days, were a part of the in eyes with large iris defects.1 acuity. To these patients, I recommend first generation to undergo refractive It will be important to counsel prosthetic soft BioColors contact surgery using methods considered this patient that his nighttime visual lenses (Orion Vision Group). They revolutionary then but that seem acuity will be reduced—not surprising may not give patients the best visual rather crude today. For pseudophakic with a pupillary opening of 1.3 mm. acuity because of the limitations of soft eyes with irregular RK incisions and What is surprising is the amount by contact lenses, but they can be made a decentered optical zone, I tend to which retinal sensitivity has increased with an opaque underprint, which is avoid scleral lenses and photoablative in patients after about 6 months, effective at reducing glare. techniques because controlling the as recently described by Artal and effects of laser vision correction colleagues.2,3 After thorough informed (LVC) can be challenging and there is consent, I would implant the XtraFocus considerable risk of complications with in the nondominant eye. If the patient LVC, even if ablation guided by corneal is happy with the outcome, I would ray tracing could be performed. discuss a potential IOL exchange for an My preferred strategy is based on a IC-8 IOL in the dominant eye. If on the principle first described by the Chinese contrary the patient is dissatisfied, the ALEKSANDAR STOJANOVIC, MD, PHD philosopher Mo-Ti in the 5th century XtraFocus could be removed. BC and elaborated upon by Christoph Probably owing to 3 decades of Scheiner in the 17th century: the neural adaptation, the patient does pinhole. Several surgical optical not mention reduced quality of vision technologies use a small aperture as a symptom despite objectively to achieve an extended depth of quite distorted corneal optics, which focus, improve near visual acuity, and probably makes treating the corneal neutralize astigmatism. These include higher-order aberrations (HOAs) corneal inlays (Kamra, CorneaGen), MICHAEL MARINO, OD unnecessary. Moreover, corneal surgery IOLs (IC-8, AcuFocus, not available in may disturb the current biomechanical the United States), and other implants This case presents two potential balance of the compromised cornea, (XtraFocus Pinhole Implant, Morcher, problems for the patient. First, he which must be considered when not available in the United States). may be experiencing a reduction in choosing between a corneal and a For this patient, I would use the BCVA with spectacles. Second, he may noncorneal approach to correcting XtraFocus, a small-aperture diaphragm be experiencing glare from the RK the refractive error. I would most likely made of a hydrophobic material incisions and the small treatment zone. choose a noncorneal approach in this whose optic portion incorporates a In these situations, I generally case, but, because therapeutic corneal black mask with a 1.3-mm central start by fitting scleral contact lenses laser surgery is my main sphere of opening. Its overall diameter is (Zenlens, Alden Optical). I would use interest, I will discuss LVC. 14 mm. The device is implanted an oblate design in this case because Regarding technique, LASIK should in the sulcus and blocks visible of the flat central corneas. It will even automatically be excluded for two light but, interestingly, not infrared out the lens clearance over the entire reasons. First, it hazards creating a poor- wavelengths. Although an Nd:YAG cornea. Too much clearance centrally quality flap that resembles pizza slices. laser capsulotomy is possible with the will reduce oxygen transmissivity, Second, treatment that will have the device in place, I would perform the which could lead to neovascularization lowest possible biomechanical impact is 30 CATARACT & REFRACTIVE SURGERY TODAY | MARCH 2020 REFRACTIVE SURGERY CASE FILES s (Figures 3–6). Significantly distorted posterior corneal optics are another problem that cannot be addressed unless total (anterior and posterior) corneal ray tracing–guided ablation is performed. It is to be hoped that this option will soon be available. n 1. Agarwal P, Navon SE. Xtra focus pinhole IOL (Morchers GMBH) a novel ap- proach to tackle irregular astigmatism and large pupillary defects with a single Figures 3–6 courtesy of Aleksandar Stojanovic, MD, PhD step surgery. BMJ Case Rep. 2019;12(4).e228902. 2. Artal P, Manzanera S. Perceived brightness with small aperture. J Cataract Refract Surg. 2018;44(6):734-737. 3. Manzanera S, Webb K, Artal P. Adaptation to brightness perception in patients implanted with a small aperture. Am J Ophthalmol. 2019;197:36-44. Figure 3. Components of the manifest refraction in eyes Figure 4. TGA programmed to treat zero sphere and with highly irregular corneas (with lenticular astigmatism cylinder will still treat anterior corneal HOAs SECTION EDITOR KARL G. STONECIPHER, MD taken out of the equation). Manifest sphere = pure sphere (including asphericity) and will remove their effect n Clinical Associate Professor of Ophthalmology, (dark blue) + spherical aberration refracting as sphere (horizontal stripes). University of North Carolina, Chapel Hill (light blue). Manifest cylinder = total corneal cylinder n Member, CRST Executive Advisory Board (orange) + odd-order HOAs refracting as cylinder (yellow). n Director of Refractive Surgery, TLC, Greensboro, North Carolina n [email protected] n Financial disclosure: Consultant (Alcon, Allergan, Bausch + Lomb, Ellex, Espansione Group, Eyevance Pharmaceuticals, EyePoint Pharmaceuticals, Johnson & Johnson Vision, Nidek, Pogotec, Presbia, Refocus Group); Research (Alcon, Allergan, Bausch + Lomb, Ellex, Espansione Group, Presbia, Refocus Group); Speaker’s bureau (AcuFocus, Alcon, Allergan, Bausch + Lomb, Ellex, Espansione Group, Johnson & Johnson Vision, Nidek, Pogotec, Presbia, Refocus Group) H. BURKHARD DICK, MD, PHD, FEBOS-CR n Director and Chairman, University Eye Hospital, Figure 5. TGA programmed to treat total corneal Figure 6. TGA programmed to treat manifest sphere and astigmatism and pure sphere will remove all cylinder will treat all the components of the manifest Bochum, Germany n the components of manifest refraction (vertical refraction (vertical stripes), but, because treating the Member, CRST International Advisory Board stripes). anterior corneal HOAs will also remove their effect on the n [email protected] manifest refraction, treatment will be doubled (area covered n Financial disclosure: Unpaid consultant by both horizontal and vertical stripes), addressing both the (AcuFocus) preferable. Among surface ablation cause and the effect of HOAs. A residual refractive error techniques, classic epithelial removal consisting of astigmatism inverse to the refractive effect of MICHAEL MARINO, OD is also contraindicated because of the the odd-order HOAs and the sphere inverse to the refractive n Director of Specialty Contact Lens Services, pronounced epithelial remodeling to effect of the spherical aberration will be induced. Triangle Visions Optometry, Apex, North Carolina be expected in this case; any ablation n [email protected] plan based on measurements taken programming of the spherocylindrical n Financial disclosure: None with the epithelium on—but applied endpoint may be challenging. after epithelial removal—would result Because TGA will correct anterior ALEKSANDAR STOJANOVIC, MD, PHD in a significant error because of the corneal HOAs, the effects of spherical n Associate Professor, University of Tromsø, Norway difference in landscape.