A COMPLETE GUIDE TO REFRACTIVE

are the health and shape of the ocular surface; other factors that may influence refractive outcomes, such as accurate PREOPERATIVE biometry and measurements; and the diagnosis of coexisting retinal disease. In the workups for all of my refractive cataract surgery patients, I use the following tests routinely, in addition to WORKUP slit-lamp and fundus examinations: corneal topography, point-of-care tear film testing, and optical and swept-source OF THE REFRACTIVE OCT biometry. Here, each of these are discussed in turn. CORNEAL TOPOGRAPHY Astigmatism management is a crucial component of CATARACT SURGERY refractive cataract surgery. Corneal topography can be a useful tool to highlight corneal pathology and to ensure that the patient has regular astigmatism. I first look at the pattern of astigmatism. Patients with corneal condi- PATIENT tions such as Salzmann nodules, anterior basement mem- brane dystrophy, or corneal ectasia will have an irregular, nonsymmetric pattern. This should signal the need for additional examination before proceeding with refractive cataract surgery. Often, patients with corneal lesions such as basement membrane dystrophy and Salzmann nodules will benefit from treatment with superficial keratectomy to restore normal corneal shape and regularity before cataract surgery. Topography can be helpful to identify dry dis- BY PREEYA K. GUPTA, MD; ease (DED) as well. Patients with areas of missing data AND BLAKE K. WILLIAMSON, MD, MPH, MS on the map or with a variegated pattern may have DED. Preoperative treatment of DED can help to restore a healthy tear film, resulting in more reliable biometric measurements. Two surgeons share valuable pointers. TEAR FILM TESTING We routinely use a questionnaire to screen patients for undiagnosed DED. In a recent study,1 we found that 80% of patients presenting for cataract surgery have signs of ocular surface dysfunction, yet many are undiagnosed. If we do not screen for DED, it is likely that patients will remain Accurate Biometry: One Key Factor in Achieving undiagnosed. A frequent cause for unhappiness after cataract surgery Successful Outcomes is exacerbation of DED symptoms. Further, untreated DED can have a negative impact on keratometry measurements,2 By Preeya K. Gupta, MD which may negatively affect refractive outcomes. Two tests that are readily available in clinical practice and easy for efractive cataract surgery has become increasingly technicians to administer are tear osmolarity and testing for popular over the past decade. More and more patients the inflammatory biomarker MMP-9. are approaching their physicians requesting premium Results from the screening questionnaire can be used to options to reduce spectacle dependence. The preoper- create a standard protocol for testing patients when DED ative workup for the refractive cataract surgery patient is suspected. Patients should be treated aggressively before Rrequires special attention to numerous details: Among them surgery to repair the ocular surface and also to establish

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biometry and swept- on the IOLMaster 700. This feature KEY COMPONENTS OF THE source OCT biometry. allows more precise correction of The latest generation astigmatism because it includes PREOPERATIVE WORKUP of biometric devices, measurement of both anterior and which use swept-source posterior corneal astigmatism. FOR REFRACTIVE CATARACT OCT, such as the The foveal OCT is also helpful to IOLMaster 700 (Carl screen for macular pathology such as SURGERY Zeiss Meditec), achieve epiretinal membrane, macular edema, better penetration and age-related macular degeneration, s Assessing the health and shape of the ocular surface into dense cataracts, among other posterior segment issues. s Accurate biometry and astigmatism measurements and they can perform If something abnormal is identified, s Diagnosis of coexisting retinal disease foveal OCT and total our technicians proceed with a full corneal astigmatism OCT. It is vital to rule out retinal measurement. I look for pathology when we offer refractive for the patient that he or she has consistency between these devices, cataract surgery, as its presence may two concomitant disease processes: with any inconsistencies preempting limit BCVA outcomes. cataract and DED. further investigation to make sure 1. Gupta PK, Drinkwater OJ, VanDusen KW, Brissette AR, Starr CE. Prevalence there are no factors causing fluctua- of ocular surface dysfunction in patients presenting for cataract surgery evalua- BIOMETRY AND OCT tion in measurement, such as DED or tion. J Cataract Refract Surg. 2018;44:1090-1096. 2. Epitropoulos AT, Matossian C, Berdy GJ, Malhotra RP, Ptovin R. Effect of tear I prefer to use two devices to corneal irregularity. Total keratometry osmolarity on repeatability of keratometry for cataract surgery planning. obtain biometric measures: optical measurement is a recent addition J Cataract Refract Surg. 2015;41:1672-1677.

Achieving 20/happy: My Favorite Preoperative Diagnostics for Refractive Cataract Surgery

By Blake K. Williamson, MD, MPH, MS

he preoperative workup is are other diagnostic adjuncts that I corneal staining, and accurate biom- crucial for success in modern have found useful for decision-making. etry. These should be considered the cataract surgery. Today, I don’t This article examines the utility of both bare minimum for a cataract workup. think surgeons can feel com- kinds of technologies. In many practices, the patient’s his- pletely confident that they are tory is taken by a scribe or technician, offeringT the best for their patients if ESSENTIALS and a practitioner might skip over they are performing only a slit-lamp There is no replacing a careful this and go straight to the eye vitals. examination and biometry in their history, slit-lamp examination with This is a mistake, in my opinion. I tend workup routine. On the other hand, I don’t think it’s necessary to go overboard and purchase three different topographers just so that you can plan a toric IOL implantation. So how does one decide which diagnostics to purchase (while still staying solvent) in today’s arms race of technology? Different surgeons use different tools, and there is no one formula for success. You need to do what works best for you and your patients. That said, there are some machines that have become gold standards as parts Figure. In one recent study, OCT was able to identify retinal issues more often than trained clinicians. Abbreviation: ERM, of the preoperative workup, and there epiretinal membrane; VMT, vitreomacular traction; ME, macular edema.

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to take the history myself for many it provides a high-definition map of retina consultation so that they can be cataract workups. the anterior curvature. But it also can treated and have their prepared Remember that how you ask cer- detect comorbidities that may rule in for eventual cataract surgery. tain questions will often change your or out certain IOL technologies. For If I see patients with good visual patient’s answers. If you say: “Have example, I wouldn’t want to place a potential but subtle epiretinal mem- you had eye trauma?” the patient multifocal IOL in a patient with irregu- branes or vitreomacular adhesions, I might say no. But ask: “Have you ever lar astigmatism or pellucid marginal may not send them for a retina consult, hit your head or been in a car wreck?” degeneration, and it is hard to see but I do show them the defect on OCT and maybe the answer changes. And those conditions without topography. so that they know they have a preexist- maybe now you’ll look a little more Topography is also useful to identify ing issue that I won’t be correcting and closely for subtle phacodonesis that DED, anterior basement membrane that it will likely prevent them from might have been skipped over previ- dystrophy, and other corneal issues. achieving perfect vision. I routinely use ously. And maybe you decide to have Finally, it is a helpful second source an imperfect macular OCT to dramati- a capsular tension ring in the OR for of K measurements. You want to be cally undersell a patient’s potential visu- this patient’s surgery. History matters. sure that the results of topography al outcome when I know that patient and biometry match with still has good visual potential. That way, regard to magnitude and I’ll likely over-deliver on expectations. meridian of cylinder; if they don’t, you need to find LAGNIAPPE “REMEMBER THAT out why. In Louisiana, we often use the Another technology I use word lagniappe, which means “a little HOW YOU ASK in addition to topography something extra.” For the purposes is wavefront aberrom- of this article, a lagniappe technol- etry with the OPD-Scan III ogy is something that might not be CERTAIN QUESTIONS (Nidek). The device pro- as mission-critical to ensure good vides wavefront autorefrac- outcomes as those we have already tion and wavefront analysis discussed. But these are technologies I WILL OFTEN CHANGE of the eye’s optical system, use routinely and would not want to including root-mean-square be without. YOUR PATIENT’S higher-order aberrations For example, I like knowing the sta- and corneal coma, which tus of the patient’s tear film, so I find can assist in IOL selection. that point-of-care testing for osmolar- ANSWERS.” I also think an OCT of ity and the inflammatory biomarker the macula is crucial for all MMP-9 is helpful in identifying DED cataract workups—even patients I may have missed otherwise. The person doing your A-scan though we still can’t bill for it. No These tests sometimes prompt me to biometry also matters. We have the human being can see subtle macular start immunomodulatory therapy and same person in our practice perform pathology as well as an OCT can. A postpone surgery until the refractive all A-scans. She does more than recent study by surgeons on the reti- situation is stable. 4,000 per year, and she is fantastic. na service at Johns Hopkins University I also find the HD Analyzer Designating one person for this task found that OCT was able to identify (Visometrics) to be extremely helpful is helpful to ensure the accuracy and 10% more epiretinal membranes and for evaluating tear breakup time and reproducibility of your measure- 25% more macular edema, and it was imaging of the meibomian glands. ments. After all, IOL choice is decided 200% more likely to identify vitreo- Poor meibomian gland health may mostly based on axial length and macular traction compared with the rule out certain IOL technologies or keratometry (K) measurements, so authors’ own dilated examinations prompt me to initiate our lid physi- you want these to be as accurate (Figure).1 cal therapy protocol. This regimen as possible. I routinely see subtle parafoveal cysts includes thermal pulsation therapy on OCT that I would not have seen and microblepharoexfoliation, with GOING TO THE NEXT LEVEL otherwise. This is important because topography and biometry repeated I believe corneal topography is a it can affect what IOL I believe the after 1 month. Many times I’ve seen crucial part of the modern cataract patient is best suited for. OCT allows patients I thought would be toric workup for many reasons. Primarily, me to identify patients in need of a IOL candidates before this treatment,

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but afterward they are not—and Finally, widefield fundus imaging lowering expectations and preventing vice versa. has been helpful in screening diabetic unhappy patients. n

I occasionally use the iDesign wave- patients and high myopes for retinal 1. Do DV, Cho M, Nguyen QD, et al. The impact of optical coherence tomog- front aberrometer (Johnson & Johnson pathologies. raphy on surgical decision making in epiretinal membrane and vitreomacular Vision) to assist in defining the mag- traction. Trans Am Ophthalmol Soc. 2006;104:161-166. nitude and meridian of astigmatism if CONCLUSION there are differences between the other It is important to have an orga- PREEYA K. GUPTA, MD biometric tests. I also occasionally use nized, comprehensive preoperative n Associate Professor of Ophthalmology, Duke Eye full field (ffERG, workup routine if you want to deliver Center, Durham, North Carolina Diopsys) in patients with lenses that 20/happy outcomes in 2019. Your n [email protected] are too dense for OCT to penetrate. testing should help you rule in or out n Financial disclosure: Consultant (Alcon, Allergan, This allows me to have some idea of certain IOLs and give you confidence Aurea, Bausch + Lomb, Carl Zeiss Meditec, their retinal functional outcome before in your surgical planning. Johnson & Johnson Vision, Novabay, Ocular I recommend cataract surgery. Further, these technologies will Science, TearLab, Tear Science, Shire) A corneal tomographer is a great enable you to diagnose many tool for defining total corneal power chronic progressive diseases that BLAKE K. WILLIAMSON, MD, MPH, MS in cataract surgery planning. It is worth have no cure and have nothing to n Refractive and anterior segment surgeon, noting, however, that the Barrett Toric do with cataracts, such as primary Williamson Eye Center, Louisiana Calculator, which is accessible on the open-angle glaucoma, age-related n Member, CRST Editorial Advisory Board ASCRS website, attempts to account macular degeneration, and DED. n [email protected] for total corneal power. This feature Positioning these issues as primary n Financial disclosure: Consultant and speaker is helpful, especially when combined problems, and cataracts as something (Alcon, Allergan, Glaukos, Johnson & Johnson with intraoperative aberrometry. temporary and fixable, will aid in Vision, New World Medical, Sight Sciences)

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