PanOptix or Trifocal IOL after LASIK or PRK (ie, Refractive Surgery)
July 3, 2020
The goal of cataract surgery is
to be as close to 20/20 for distance, intermediate, and reading vision without
glasses, but this usually requires special implants, such as the Trifocal-PanOptix
intraocular lens (IOL) and Femtosecond Laser Assisted Cataract Surgery
which also helps decrease corneal astigmatism by making small microscopic cuts
in the cornea. While there is not a 100% guarantee a patient who chooses both
the Pan-Optix and Femtosecond Laser-Assisted Cataract surgery will be glasses
free, publications and our experience has shown over a 90% chance of being
glasses-free for distance and intermediate and over an 87% chance of being
glasses-free for reading. For patients who are jewelers or do very close work,
they have a higher chance of needing reading glasses even with the PanOptix. Some
patients who want to be completely glasses-free for reading would have to
choose intraocular implants in 1 or both eyes that are between -1.75-2.50D but
then would need glasses for intermediate and distance.
An issue arises when a patient has already had Refractive Surgery, such as LASIK or PRK. More than 40 million people have had LASIK or PRK around the world. Many of these patients will need cataract surgery in the future which can cause vision issues after cataract surgery. Many of these patients have enjoyed 20/20 vision for distance, intermediate, and reading, but after cataract surgery, the eye’s natural eye lens is removed and accommodation (ability to focus for intermediate and reading) will disappear completely if not already gone with aging.
We place an implant or intraocular lens IOLs so a patient can focus again for distance: the first type is called a Monofocal (for 1 visual plane: usually for distance).
New-Technology implants (multifocal implants, Extended Depth of Focus implants like Symfony, or Trifocal implants like PANOPTIX) give a non-refractive patient a high chance at being glasses-free for reading, intermediate, and distance (though not 100% guaranteed). These new implants have their positive and negatives but the majority of patients are thrilled with these implants but they can cause vision quality issues for patients who have had refractive surgery (ie LASIK, PRK) as well as a refractive surprise: where the IOL implant power is completely incorrect (which is rarer given we use ORA intraoperative interferometry to triple check the implant power for every post-refractive patient who has cataract surgery (but it can still happen as LASIK and PRK change the cornea’s shape significantly which interfere with our implant calculations.)
I and many surgeons spend a great deal of time trying to convince post-refractive patients to NOT have multifocal implants, Extended Depth of Focus implants like Symfony, or Trifocal implants like PANOPTIX given the risks and the newer implants are not FDA approved for post-refractive surgery patients. I often try to convince these patients to go with MONOFOCAL IOLS as they have the least risk of causing haloes and glare (though not 0% guaranteed either).
Still there are many patients who insist that these new technology implants (i.e., PanOptix, Symfony, Multifocals) are the only ones they want to try. This is a new category of patients that are being intently studied as some brains CAN tolerate the new images these new IOLs present. Some will likely hate these new IOLs but when a patient pushes to have the new implants inserted, they are highly motivated to make it work and ignore extra glare or haloes all these new implants can cause.
My team has now done about 10 patients who have had LASIK or PRK and have had PanOptix or Symfony implanted in one or both eyes. So far, patients have been very happy. We have not had to explant any yet. But that is a risk: we might need to change out the implant for a MONOFOCAL but patients know this. I suspect these patients are working with the images their eyes receive to train the brain to accept them and deal with the negative components of these implants.
There are some things we can do to help assess the risk the patient will not be happy with the new-technology implant. IOL power calculation is one of the most difficult parts for cataract operation after refractive surgery.
In every post-Lasik/PRK patient having cataract surgery, we use many IOL formulas, such as Haigis-L, SHammas, Barret True K, Pentacam, OCT. With non-refractive patients, we usually only use one formula.
We always use ORA intraoperative interferometry to triple check the implant we are putting in. Different studies show different formulas to be the best. A recent one showed Haigis-L turned out to have the highest percentage of cases that achieved the refraction of targeted SE ±0.50 D and SE ±1.00 D [4]. A meta-analysis by Chen et al. also concluded that the clinical inquiry was inaccurate in predicting postoperative refraction as compared to the Haigis-L formula [5]. In this case, the Haigis-L formula again proved to be reliable to attain emmetropia.
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Furthermore, a thorough preoperative evaluation is fundamental for the success of the surgery. The recommended criteria for new-Technology IOLs (PANOPTIX, Symfony, multifocal IOL implantation in post-refractive patients is noted here below but there are patients who know they do not meet all these criteria and still proceed with the surgery and are happy with the results. Long term studies are needed to see why some patients will fail the below criteria and still be happy with results while as others will not.
Recommended: Do not use soft Contact Lens for at least 1wk before A-scan and before surgery if ORA will be used in the operative eye. Do not use a Hard Contact lens for 3wks before A-Scan and before surgery if ORA will be used in the operative eye.
Highly recommended: 1. corneal astigmatism of no more than 1.25D, 2. root mean square (RMS) of corneal HOAs within 6.0 mm zone no more than 0.50 mm, and 3. kappa angle no more than 0.29. 4. post-LASIK eye necessitates a uniform, well-centered and closely-attached corneal flap for multifocal IOL implantation. 5. treat dry eye conditions: patient again needs to know the quality of vision is also dependent on the tear film. Meibography should be done before surgery to give prognosis about dry eye symptoms, such as foreign body sensation, irritation, dryness, blurry vision, itching, redness, pain. I recommend Lipiflow or IPL if meibomian glands have scar tissue or the patient has signs of dryness on corneal exam. We also prescribe Xiidra, Restasis, Autologous Serum, PRP drops to help prevent issues after surgery from dryness.
Here is more information by Dr. Degan about what each patient can see based on age and eye’s status: 1. Top line=young 25yo 2. Dark green line: 50 yo healthy patient who can’t see to read or computer much but good for distance 3. Yellow Line: what you can see if we implant a MONOFOCAL implant: your distance vision will be better than computer or reading (which is minimal unless we purposely use mini-monovision). 4. Orange: a patient with a Multifocal Restor which we do not use much anymore given risk of halos & glare. 5. Teal colored: this is the vision one can get with a PanOptix Trifocal implant which most patients love. As you can see, the risk of still needing reading glasses for close-up is not 0% bu its better than the other options.
6. Pink line: Cataracts usually really decrease vision for distance, intermediate, reading and cause a lot of halos and glare. This is why surgery is needed.
More information about PanOptix which is becoming a surgeon-favorite as patients are really happy with this implant.
AcrySof IQ PanOptix Model TFNT00 (Alcon Laboratories, Fort Worth, TX) is a a.1-piece aspheric hydrophobic presbyopia-correcting intraocular lens (IOL) launched in 2015 in Europe and approved in the US August, 2019.
b. Unlike traditional trifocal IOLs that usually have an intermediate focal point of 80 cm, the PanOptix IOL is designed to have an intermediate focal point of 60 cm (arms-length), a more natural and comfortable working distance to perform functional tasks on computers, laptops, mobiles, among others & provides a more comfortable near-to-intermediate range of vision than traditional trifocal IOLs
c. The non-apodized PanOptix IOL uses the ENhanced LIGHT ENergy (ENLIGHTEN; Alcon Laboratories, Fort Worth, TX) optical technology that provides high (88%) utilization of light energy,
d. low dependence on pupil size in all lighting conditions,
e. is an ultraviolet (UV) and blue light filtering, non-apodized, foldable presbyopia-correcting IOL.
f. it is a single-piece IOL has a central biconvex optic, with an innerdiffractive and an outer refractive zone, and is made of a hydrophobic material acrylate/methacrylate copolymer and has 2 open-loop haptics
g. The PanOptix IOL is based on a quadrifocal (4 foci) design and uses a proprietary optical technology, ENLIGHTEN, to redistribute the focal point at 120 cm to the distance focal point for amplified performance. This results in 2-step heights that is equal to 2 add powers/2 focal points (plus distance from base curve. Light is split to 3 foci (distance: ∞, intermediate at 60 cm, and near at 40 cm). The 4.5 mm non-apodized, diffractive zone allows high light utilization, transmitting 88% of light to the retina at a 3.0 mm pupil size, and provides optimized performance in a wide range of lighting conditions due to low dependence on the pupil size. This light energy is distributed 25% each for near and intermediate and 50% for distance vision.
h. The lens is 13.0 mm in diameter with a central optic of 6.0 mm and is available in a diopter (D) range of +6.0 to +30.0 D (0.5 D increments) and +31.0 D to +34.0 D (1.0 D increments). The posterior lens surface is spherical, and the anterior surface is aspheric with a diffractive surface on the central 4.5 mm portion of the optic zone, and divides the incoming light to create an intermediate addition power of +2.17 D (60 cm) and a +3.25 D (40 cm) near add power (Table 1). The anterior surface is designed with negative spherical aberration to compensate for the positive spherical aberration of the average human cornea.
i. other commercially available trifocal IOLs: A. Not approved in US: FineVision Micro F (PhysIOL, Liege, Belgium), the AT LISA tri 839MP (Carl Zeiss Meditec AG, Jena, Germany) B. Approved in US but not as good for reading compared to PANOPTIX: the extended depth of focus IOL, TECNIS Symfony (Abbott Medical Optics, Santa Ana, CA).
The difference between a traditional trifocal IOL and PanOptix IOL:
Traditional IOLs have 2 added powers with an intermediate focal point at 80 cm. Quadrifocal IOLs have 3 added powers; this provides more continuous vision but may compromise distant contrast.
The ENLIGHTEN optical technology used inPanOptixredirects light from the third step height (120 cm) to distance for amplified performance. IOL indicates intraocular lens.
Femtosecond laser-assisted cataract surgery with implantation of a diffractive trifocal intraocular lens after laser in situ keratomileusis: a case report
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
We report for the first time, a case of femtosecond laser-assisted cataract surgery (FLACS) with implantation of a diffractive trifocal intraocular lens (IOL) after laser in situ keratomileusis (LASIK).
Case presentation
A 60-year-old man underwent FLACS uneventfully 15 years after myopic LASIK. An AT Lisa tri 839MP IOL was implanted with the expectation of spectacle independence. The Haigis-L formula was chosen for calculation of the IOL power and it provided reliable results. Three months postoperatively, the uncorrected visual acuities were 0.00 logMAR for distance, 0.10 logMAR for intermediate, and 0.10 logMAR for near.
Conclusions
This case suggested that FLACS presents a feasible surgical technique for post-LASIK eyes and that implantation of trifocal IOL can achieve good visual performance in strictly selected cases after myopic LASIK.
There are a growing number of patients who wish to be spectacle independent after cataract surgery, and this includes some of the millions of people worldwide who have undergone laser in situ keratomileusis (LASIK). Ophthalmologists will encounter many cataract cases that have had previous LASIK surgery and they should have the knowledge to deal with these cases efficiently to achieve the best possible visual and refractive outcomes [1]. Femtosecond laser–assisted cataract surgery (FLACS) has become increasingly more common for its many advantages offered [2]. At the same time, various kinds of multifunctional intraocular lens (IOL) were designed [3] to provide functional visual restoration after cataract surgery. Nowadays, the combination of FLACS with multifocal IOLs has come to the cutting edge of cataract surgery. However, few studies had shed light on whether post-LASIK patients would benefit from this technique combo. Here we report a case of FLACS with the implantation of a diffractive trifocal IOL after LASIK.
A 60-year-old man was diagnosed with nuclear cataract in his right eye about 15 years after myopic LASIK surgery. His corrected distance visual acuity (CDVA) of the right eye was 0.52 logMAR with the refraction of − 4.50/− 0.75*29. He asked for a FLACS and desired spectacle independence after the IOL implantation. Corneal topography (Pentacam, Oculus Optikgerate GmbH, Wetzlar, Germany) showed a uniform, well-centered corneal flap (Fig. 1a, b), with a total corneal astigmatism of 0.9D, and a corneal irregular astigmatism of 0.115 μm. Besides, the 6 mm zone corneal spherical aberration (SA) was 0.392 μm while the angle kappa was 0.15. After a series of thorough assessments, we decided to implant a multifocal IOL with negative SA. For IOL power calculations, the standard IOLMaster (Carl Zeiss Meditec,Jena, Germany) biometry was performed and the Haigis-L formula was chosen to determine an IOL power of +23D for emmetropia. A steep merdian corneal incision was designed at 140 degree according to the Pentacam results.
Corneal topography preoperatively (a, b) and at 3 months postoperatively (c, d)
The LenSx laser system (LenSx Laser; Alcon Laboratories, Inc., Fort Worth,TX, USA) was used to perform the surgery. After the patient’s eye was properly docked to the system, the arc cuts of the primary and side port incision were adjusted towards the limbus, anterior to the conjunctival vascular arcades, under the guided of the LenSx real-time imaging system. A 2.0 mm primary corneal incision (Fig. 2a), a 1.0 mm side port incision and a 5.0 mm capsulotomy were created by the laser. Nuclear prefragmention was performed to obtain 6 pieces in a cross pattern (Fig. (Fig.2b).2b). Then phacoemulsification was proceeded in a standard stop-and-chop manner with the Stellaris system (Bausch + Lomb Laboratories, Rochester, NY, USA), and an AT Lisa tri 839MP IOL (Carl Zeiss Meditec AG) was implanted right afterwards. All surgical procedures were uneventful. The patient was instructed to apply topical dexamethasone tobramycin for 2 weeks and pranoprofen for 1 month postoperatively.
a AS-OCT image depicts the architecture of clear corneal incision. b Screenshot taken after femtosecond laser treatment completed. The primary corneal incision was made at 140 degree, consistent with the steep merdian axis
Anterior segment optical coherence tomography (AS-OCT, Carl Zeiss Meditec) showed a smooth corneal flap 1 week after FLACS (Fig. 3a). The distance from the external wound opening to the corneal flap edge was 0.15 mm. At 3 months postoperatively, the IOL was well centered in the capsule (Fig. (Fig.3b).3b). Pentacam showed a uniform corneal flap (Fig. 1c, d) with slightly decreased total corneal astigmatism and corneal SA (Table 1). Uncorrected visual acuitis were 0.00 LogMAR for distance, 0.10 LogMAR for intermediate at 80 cm, 0.10 LogMAR for near at 40 cm. The defocus curve (Fig. (Fig.3c)3c) showed an optimal visual acuity at -3D apart from 0D, but maintained a functional range of visual acuity across from 0D to − 3.5D with visual acuity no less than 0.22 logMAR. Results of ocular aberrations (OPD Scan, Nidek Co., Ltd.) for 5 mm diameter pupils showed 0.831um of high order aberration (HOA), 0.648um of coma, 0.327um of trefoil, 0.119um of tetrafoil, and 0.311um of SA. Contrast sensitivity (CS, CSV-1000, Vector Vision, Greenville, OH) at 4 spatial frequencies (A: 3 cpd, B: 6 cpd, C:12 cpd and D:18 cpd) under both mesopic (3 cd/m2) and photopic (85 cd/m2) conditions were at a relatively low level within the normal range (Fig. 4). Despite a mild halo, the patient was very satisfied with his vision.
a AS-OCT taken at 1 week postoperatively. The distance from the external wound opening to the corneal flap edge was 0.15 mm. Bar,1 mm. b Slitlamp examination showed well centered IOL with a 360° overlapping capsular edge at 3 months postoperatively. c Defocus curve at 3 months postoperatively
Table 1
Preoperative and postoperative pentacam measurements
Preoperative
Postoperative
1 week
3 months
K1
37.5@49.6
37.2@56.2
37.7@69.2
K2
38.4@139.6
37.6@146.2
38.2@159.2
Total Astig(D)
0.9
0.4
0.5
SA at 6 mm zone(um)
0.392
0.305
0.375
Irregular astig(um)
0.115
0.238
0.161
Pentacam showed slightly decreased postoperative total corneal astigmatism and corneal SA. Besides, there was only a slight change in astigmatism and axial direction at 3 months compared to that of 1 week postoperative
Contrast sensitivity under mesopic and photopic conditions at 3 months postoperatively. Grey area shows the normal range of contrast sensitivity among 56–75 year-old people
The application of femtosecond laser (FSL) in cataract surgery improves the precision of corneal incision location and extent. FSL also provides a precise and well-centered capsulotomy which contributes to the proper position of the IOL that may be related to refractive outcome improvements [4]. In this patient, the computer-controlled accurate steep merdian incision successfully decreased the total corneal astigmatism and ensured visual outcomes of this patient. Well-centered trifocal IOL with a 360° overlapping capsular edge could reduce the incidence of myopization and HOAs changes. In post-LASIK eyes, postoperative corneal edema after cataract surgery may accumulate in the flap interface and the flap itself, causing early transient central corneal steepening and consequent myopic shift that could disappear after the corneal edema resolves [1]. However, the incidence of this complication could be reduced by FSL assisted lens fragmentation, which helps reduce phacoemulsification energy requirements, protect corneal endothelial cells, and thus shorten the recovery period and improve visual outcomes [5].
As for safety, although vacuum suction during FLACS can lead to an increase of the intraocular pressure, it was proved to be feasible for those with previous corneal surgeries, such as radial keratotomy [6] or even penetrating keratoplasty [7]. In this patient, the docking and suction procession did not have any negative effect on the corneal flap, and no intraoperative complications were observed throughout the surgery either. However, the AS-OCT showed a very short distance between the external wound opening and the corneal flap edge postoperatively. Zhu et al. found that laser corneal incisions were closer to the center of the cornea than manual corneal incisions, and they thought this may be related to the possible inaccuracy or uncertainty in corneal incision positioning of the LenSx machine [8]. So here we have to point out that a laser-assisted corneal incision may increase the risk of intersection between the incision and the corneal flap. Future studies should be conducted to confirm this hypothesis.
Post-LASIK patients are often focusing on better visual quality and they are keen to take off spectacles, even after developing cataract. A few studies have reported that the implantation of multifocal IOLs in patients who underwent previous myopic LASIK provided good visual acuities for distance and near range [9]. The AT LISA tri839MP, a diffractive trifocal preloaded IOL with an asphericity of − 0.18, provides a near addition (add) of + 3.33 D and an intermediate add of + 1.66D. It was developed to overcome the photic phenomena and the poor level of intermediate vision of traditional multifocal IOLs [10]. It is well known that laser refractive surgery would modify the corneal shape and induce positive spherical aberration (SA) while correcting myopia [11]. The negative SA of AT LISA tri839MP could partially compensate SA and help retain good mesopic distance vision.
Furthermore, thorough preoperative evaluation was fundamental for the success of this operation. The inclusion criteria for multifocal IOL implantation in our eye center are corneal astigmatism of no more than 1.25D, root mean square (RMS) of corneal HOAs within 6.0 mm zone no more than 0.50 mm, and kappa angle no more than 0.29. The criteria are consistent with those in the studies of Monaco [12] and Mojzis [9]. In this case, the patient met all the above requirements despite of his myopic LASIK history. In this case, we propose that post-LASIK eye necessitates a uniform, well-centered and closely-attached corneal flap for multifocal IOL implantation. Another noticeable situation is the possible aggravation of dry eye after FLACS [13], since that LASIK procedure had already potentiate the instability of tear film. Therefore, careful evaluation of dry eye and timely treatment before surgery is recommended.
IOL power calculation remains one of the most difficult parts for cataract operation after refractive surgery. In Wong’s study, the Asian eyes with previous myopic LASIK or photorefractive keratectomy (PRK) had cataract surgeries with IOL power calculated by 4 formulas. Haigis-L formula turned out to have the highest percentage of cases that achieved the refraction of targeted SE ±0.50 D and SE ±1.00 D [14]. A meta-analysis by Chen et al. also concluded that the clinical inquiry was inaccurate in predicting postoperative refraction as compared to the Haigis-L formula [15]. In this case, the Haigis-L formula again proved to be reliable to attain emmetropia.
In conclusion, our report shows that, for cataract patients with previous LASIK, FLACS with implantation of the AT LISA tri839MP can be an effective option to obtain spectacle independence.
This work was supported by the National Natural Science Foundation of China (81600716), the Key Research and Development Plan of Zhejiang Province Science and Technology Hall (2017C03046), General Scientific Research Project of Zhejiang Province Education Department (Y201738741).
Availability of data and materials
All data generated and analyzed during this study are included in this article.
All authors conceived of and designed the study. All authors were involved in the data analysis. WW and NS did the patient follow-up, collected data and drafted the article. LX and CX reviewed the literature. ZYN revised the manuscript. XW did the surgery and drafted the article. All authors reviewed the manuscript. All authors read and approved the final manuscript.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.
1. Alio JL, Abdelghany AA, Abdou AA, Maldonado MJ. Cataract surgery on the previous corneal refractive surgery patient. Surv Ophthalmol. 2016;61(6):769–777. doi: 10.1016/j.survophthal.2016.07.001. [PubMed] [CrossRef] [Google Scholar]
2. Grewal DS, Schultz T, Basti S, Dick HB. Femtosecond laser-assisted cataract surgery–current status and future directions. Surv Ophthalmol. 2016;61(2):103–131. doi: 10.1016/j.survophthal.2015.09.002. [PubMed] [CrossRef] [Google Scholar]
3. de Vries NE, Nuijts RM. Multifocal intraocular lenses in cataract surgery: literature review of benefits and side effects. J Cataract Refract Surg. 2013;39(2):268–278. doi: 10.1016/j.jcrs.2012.12.002. [PubMed] [CrossRef] [Google Scholar]
5. Chen X, Yu Y, Song X, Zhu Y, Wang W, Yao K. Clinical outcomes of femtosecond laser-assisted cataract surgery versus conventional phacoemulsification surgery for hard nuclear cataracts. J Cataract Refract Surg. 2017;43(4):486–491. doi: 10.1016/j.jcrs.2017.01.010. [PubMed] [CrossRef] [Google Scholar]
6. Noristani R, Schultz T, Dick HB. Femtosecond laser-assisted cataract surgery after radial keratotomy. J Refract Surg. 2016;32(6):426–428. doi: 10.3928/1081597X-20160428-03. [PubMed] [CrossRef] [Google Scholar]
7. Cao D, Wang S, Wang Y. Femtosecond laser-assisted cataract surgery after penetrating keratoplasty: a case report. BMC Ophthalmol. 2017;17(1) [PMC free article] [PubMed]
8. Zhu S, Qu N, Wang W, Zhu Y, Shentu X, Chen P, Xu W, Yao K. Morphologic features and surgically induced astigmatism of femtosecond laser versus manual clear corneal incisions. J Cataract Refract Surg. 2017;43(11):1430–1435. doi: 10.1016/j.jcrs.2017.08.011. [PubMed] [CrossRef] [Google Scholar]
9. Chang JS, Ng JC, Chan VK, Law AK. Visual outcomes, quality of vision, and quality of life of diffractive multifocal intraocular Lens implantation after myopic laser in situ Keratomileusis: a prospective, observational case series. J Ophthalmol. 2017;2017:6459504. doi: 10.1155/2017/6459504. [PMC free article] [PubMed] [CrossRef] [Google Scholar]
11. Iijima K, Kamiya K, Shimizu K, Igarashi A, Komatsu M. Demographics of patients having cataract surgery after laser in situ keratomileusis. J Cataract Refract Surg. 2015;41(2):334–338. doi: 10.1016/j.jcrs.2014.05.045. [PubMed] [CrossRef] [Google Scholar]
12. Monaco G, Gari M, Di Censo F, Poscia A, Ruggi G, Scialdone A. Visual performance after bilateral implantation of 2 new presbyopia-correcting intraocular lenses: trifocal versus extended range of vision. J Cataract Refract Surg. 2017;43(6):737–747. doi: 10.1016/j.jcrs.2017.03.037. [PubMed] [CrossRef] [Google Scholar]
13. Yu YH, Hua HX, Wu MH, Yu YB, Yu WS, Lai KR, Yao K. Evaluation of dry eye after femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2015;41(12):2614–2623. doi: 10.1016/j.jcrs.2015.06.036. [PubMed] [CrossRef] [Google Scholar]
14. Wong CW, Yuen L, Tseng P, Han DC. Outcomes of the Haigis-L formula for calculating intraocular lens power in Asian eyes after refractive surgery. J Cataract Refract Surg. 2015;41(3):607–612. doi: 10.1016/j.jcrs.2014.06.034. [PubMed] [CrossRef] [Google Scholar]
15. Chen X, Yuan F, Wu L. Metaanalysis of intraocular lens power calculation after laser refractive surgery in myopic eyes. J Cataract Refract Surg. 2016;42(1):163–170. doi: 10.1016/j.jcrs.2015.12.005. [PubMed] [CrossRef] [Google Scholar]
