Comparison of Contrast Sensitivity and Through Focus in Small-Aperture Inlay, Accommodating Intraocular Lens, or Multifocal Intraocular Lens Subjects

Comparison of Contrast Sensitivity and Through Focus in Small-Aperture Inlay, Accommodating Intraocular Lens, or Multifocal Intraocular Lens Subjects

We agree that an aggressive corneal wound healing response with a significant refractive shift is not a common outcome using an optimized surgical tec...

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We agree that an aggressive corneal wound healing response with a significant refractive shift is not a common outcome using an optimized surgical technique and the current version of the KAMRA inlay. As they have pointed out, such outliers were more commonly seen with earlier versions of the inlay implanted under thick flaps,2 sometimes combined with simultaneous LASIK using the same flap rather than a pocket3 or with suboptimal surgical protocols. Through extensive research, we have identified key variables that contribute to more activated wound healing and subsequent refractive change. For example, in the clinical trial (N ¼ 508) surgical protocol, surgeons were allowed to use their preferred technique and laser settings. The KAMRA inlay was inserted into a lamellar pocket (93%) or under a flap (7%) at different depths (from 170 to 270 mm). Additionally, the method of lamellar resection (femtosecond laser or mechanical microkeratome), spot and line separation, and laser energy varied between investigational sites. The results from the clinical trial demonstrated that subjects implanted with the KAMRA inlay into a stromal pocket created using a femtosecond laser _6 3 6 mm spot and line separation settings achieved with < significantly better uncorrected near visual acuity and refractive stability and reported a higher level of satisfaction with _6 3 6 fewer removals. Over 95% of the subjects in the < pocket subgroup (n ¼ 166) remained within 61.00 diopter of manifest refractive spherical equivalent (MRSE) between 18–24, 24–30, and 30–36 months. Furthermore, among the < _6 3 6 pocket subgroup, there was a trend toward better _230 mm). refractive stability with deeper stromal pockets (> A spectrum of wound healing responses is not an unexpected postoperative reaction to keratorefractive procedures.4,5 In KAMRA inlay patients, the incidence and degree of corneal wound healing response can be _6 3 6 mm minimized by using a femtosecond laser with < spot and line separation for creation of a smooth lamellar pocket and by implanting the inlay in a deeper pocket. The wound healing response can also be modulated by treating it with steroids.5 In the clinical trial, the treatment of subjects who experienced a wound healing response at 6 months was variable. Only 5% of subjects who experienced a wound healing response in the clinical trial had a recurrence of the response after treatment, and in such cases the best course of action would be surgical intervention such as enhancement or removal. The clinical trial data suggest that earlier removal leads to better recovery of bestcorrected visual acuity (Fisher exact test, P < .0001).6 SRIVIDHYA VILUPURU LING LIN

Irvine, California JAY S. PEPOSE

St Louis, Missouri SEE THE ORIGINAL ARTICLE FOR ANY DISCLOSURES OF THE authors.

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REFERENCES

1. Vilupuru S, Lin L, Pepose JS. Comparison of contrast sensitivity and through focus in small-aperture inlay, accommodating intraocular lens, or multifocal intraocular lens subjects. Am J Ophthalmol 2015;160(1):150–162. 2. Dexl AK, Jell G, Strohmaier C, et al. Long-term outcomes after monocular corneal inlay implantation for the surgical compensation of presbyopia. J Cataract Refract Surg 2015; 41(3):566–575. 3. Tomita M, Waring GO 4th. One-year results of simultaneous laser in situ keratomileusis and small-aperture corneal inlay implantation for hyperopic presbyopia: comparison by age. J Cataract Refract Surg 2015;41(1):152–161. 4. Abbouda A, Javaloy J, Alio´ JL. Confocal microscopy evaluation of the corneal response following AcuFocus KAMRA inlay implantation. J Refract Surg 2014;30(3):172–178. 5. Erie JC, McLaren JW, Hodge DO, Bourne WM. Long-term corneal keratoctye deficits after photorefractive keratectomy and laser in situ keratomileusis. Trans Am Ophthalmol Soc 2005;103:56–66. 6. Alio´ JL, Abbouda A, Huseynli S, Knorz MC, Durrie DS. Removability of a small aperture intracorneal inlay for presbyopia correction. J Refract Surg 2013;29(8):550–556.

Comparison of Contrast Sensitivity and Through Focus in Small-Aperture Inlay, Accommodating Intraocular Lens, or Multifocal Intraocular Lens Subjects EDITOR: THE SURGICAL CORRECTION OF PRESBYOPIA IS ONE OF THE

hot topics of refractive surgery. For this reason, we have read with great interest the article by Vilupuru and associates,1 recently published in the American Journal of Ophthalmology. The authors should be congratulated because this is the first report that evaluates the contrast sensitivity and the visual outcomes of KAMRA intracorneal inlay and compared them with 3 intraocular lenses (IOLs) (accommodating or multifocal) for the treatment of presbyopia. However, we have concerns about 2 facts of this study. First, when reading the methods, we have observed that the patients included in the KAMRA group had a preoperative spherical equivalent of þ0.50 diopter to 0.75 diopter. Given the fact that a mild myopic defect can partially compensate presbyopia, we believe that the visual outcomes reported in the KAMRA group may have been overestimated; that is, the improvement in intermediate and near vision in those patients with myopia would be explained, at least in part, by the myopic defect in the nondominant eye (monovision-like situation) and not by the KAMRA performance in itself. Second, the main conclusion of the study is that KAMRA inlay provides better results than premium IOLs in terms of contrast sensitivity and distance and

AMERICAN JOURNAL OF OPHTHALMOLOGY

JANUARY 2016

intermediate vision. Nevertheless, we have previously reported the visual outcomes of LASIK-induced monovision,2 another widely used method for the correction of presbyopia, and it is remarkable that our results are comparable to those reported by Vilupuru and associates1 in the KAMRA group. For this reason, we do not see the real benefits of the KAMRA inlay compared to simple monovision. In fact, the authors suggest that a potential advantage of the KAMRA inlay is its easy removability compared to an IOL exchange if the patient is dissatisfied. Nevertheless, several cases of moderate to severe loss of best-corrected visual acuity have been reported after intracorneal inlay explantation, due to epithelial perilenticular opacity.3 On the other hand, and in contrast with other techniques to correct presbyopia (such as intracorneal inlay, multifocal IOLs, or multifocal corneal laser ablation), a patient with LASIK-induced monovision can easily improve the distance or near vision for certain tasks by wearing glasses. For all these reasons, we believe that further studies are needed to ensure the real advantages and disadvantages of the various procedures currently available for the surgical treatment of presbyopia. MONTSERRAT GARCIA-GONZALEZ MIGUEL A. TEUS

Madrid, Spain FUNDING/SUPPORT: NO FUNDING OR GRANT SUPPORT. Financial disclosures: The following authors have no financial disclosures: Montserrat Garcia-Gonzalez and Miguel A. Teus. All authors attest that they meet the current ICMJE criteria for authorship.

REFERENCES

1. Vilupuru S, Lin L, Pepose JS. Comparison of contrast sensitivity and through focus in small-aperture inlay, accommodating intraocular lens, or multifocal intraocular lens subjects. Am J Ophthalmol 2015;160(1):150–162. 2. Garcia-Gonzalez M, Teus MA, Hernandez-Verdejo JL. Visual outcomes of LASIK-induced monovision in myopic patients with presbyopia. Am J Ophthalmol 2010;150(3):381–386. 3. Alio´ JL, Mulet ME, Zapata LF, Vidal MT, De Rojas V, Javaloy J. Intracorneal inlay complicated by intrastromal epitelial opacification. Arch Ophthalmol 2004;122(10):1441–1446.

REPLY WE THANK DRS. GARCIA-GONZALEZ AND TEUS FOR THEIR

interest and discussion of our recent publication. In response to their first comment that the visual outcomes in the KAMRA group may have been overestimated as a result of mild myopia in the inlay eye, we refer to Figure 4 of our article,1 which shows the cumulative percentages and means of monocular distance-corrected far, intermediate, and near visual acuities. Distance-corrected visual acuVOL. 161

ity accounts for refractive error, making the patients essentially emmetropic, and no clinically significant difference was found between distance-corrected and uncorrected visual acuities at intermediate or near. Further, the mean binocular uncorrected distance visual acuity with KAMRA inlay was 1.40 decimal (range, 0.95–1.40), which is better than that reported by the authors for laser in situ keratomileusis (LASIK)-induced monovision at 1.08 decimal (range, 0.7–1.25).2 When the visual acuity results are stratified by preoperative refractive error (myopic: manifest refraction spherical equivalent [MRSE] < 0.0 diopter, n ¼ 101; emmetropic: MRSE ¼ 0.0 diopter, n ¼ 42; and hyperopic: MRSE > 0.0 diopter, n ¼ 184), the uncorrected visual acuities (logMAR) at intermediate are 0.15 6 0.13, 0.19 6 0.14, and 0.21 6 0.14, respectively. Uncorrected visual acuities at near are 0.15 6 0.13, 0.21 6 0.16, and 0.24 6 0.16, respectively. These differences in visual acuity between the myopic and the hyperopic groups approximate only 1 line of acuity, whereas the difference in near visual acuity before and after KAMRA implantation is between 3 and 4 lines of acuity. Therefore, the improvement in intermediate and near visual acuity with KAMRA is primarily due to the extended depth of focus provided by the small-aperture inlay; mild myopia adds a nominal benefit. However, pairing the KAMRA inlay with a small magnitude of myopia optimizes the intermediate and near visual acuity range while maintaining excellent uncorrected visual acuity at far (mean 0.009 6 0.11 logMAR). Monovision LASIK with sufficient offset (add) between the two eyes to improve near vision to a clinically meaningful degree degrades far vision quality as well as binocularity. Postoperative stereopsis in KAMRA patients has been demonstrated to be no different than preoperative stereopsis.3 Regarding the second comment on vision with KAMRA inlay being comparable to monovision, we refer to the article on the impact of small aperture on stereoacuity with monovision.4 Fernandez and associates showed that introducing a small aperture to þ0.75 D monovision improved stereopsis compared to þ0.75 D of traditional monovision.4 Finally, the article published by Alio´ and associates,5 from which the authors cited loss of best-corrected visual acuity after inlay removal, was an observational case series on patients implanted with a hydrogel corneal inlay. In distinction, the KAMRA inlay (ACI7000PDT) is made of polyvinylidene fluoride, is much thinner at 6 mm, and harbors 8400 microperforations in the annulus to further enhance the flow of glucose and other metabolites. Recently, Alio´ and associates6 reported on topographic and aberrometric changes 6 months after KAMRA inlay removal. Alio´ and associates concluded the KAMRA inlay to be safe, with good recovery of corneal topography and aberrometry after removal.

CORRESPONDENCE

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