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ORIGINAL ARTICLE
Year : 2017  |  Volume : 30  |  Issue : 2  |  Page : 512-516

Effectof Nd: YAG laser capsulotomy size on visual outcomes of the eye, intraocular pressure, and macular thickness


1 Department of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Ophthalmology, El-Matariya TeachingHospital, Cairo, Egypt

Date of Submission19-Jul-2016
Date of Acceptance11-Dec-2016
Date of Web Publication25-Sep-2017

Correspondence Address:
Khaled A Shahata El-Sayed
Tukh, Kalubia, 13741
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.215453

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  Abstract 

Objective
The objective of this study was to show the effect of neodymium:yttrium–aluminum–garnet (Nd:YAG) laser capsulotomy size on visual outcomes of the eye, intraocular pressure(IOP), and macular thickness.
Background
Although Nd:YAG laser capsulotomy has been found to be safe and effective, events such as retinal detachment, cystoid macular edema, and rise in IOP tend to occur after Nd:YAG laser capsulotomy.
Materials and methods
A total of 56 eyes of 56patients were enrolled in this prospective comparative study with posterior capsular opacification following uncomplicated cataract surgery with posterior chamber intraocular lens implantation. All patients were examined before Nd:YAG laser capsulotomy and 1, 4, and 12weeks after Nd:YAG laser capsulotomy for best-corrected visual acuity(VA), IOP, and foveal thickness. Patients were divided into two groups based on the postoperative capsulotomy size: group1, capsulotomy size less than 3.9mm; group2, capsulotomy size equal to or larger than 3.9mm.
Results
We found significant improvement in VA in both groups, with no significant effect of capsulotomy size on the improvement in VA. IOP increased 1week postoperatively in both groups, but IOP rise in group2 was higher than in group1; both groups had increased central foveal thickness at 1week postoperatively. The degree of foveal thickening was similar in both groups.
Conclusion
Patients who underwent a larger capsulotomy size have more elevation in IOP. Rise in central foveal thickness was similar in large and small capsulotomy groups, and the improvement in VA was not affected by the capsulotomy size.

Keywords: intraocular pressure, macular thickness, neodymium:yttrium–aluminum–garnet laser capsulotomy size, visual outcomes of the eye


How to cite this article:
El-Saadani AKI, El-Morsy OA, Shahata El-Sayed KA. Effectof Nd: YAG laser capsulotomy size on visual outcomes of the eye, intraocular pressure, and macular thickness. Menoufia Med J 2017;30:512-6

How to cite this URL:
El-Saadani AKI, El-Morsy OA, Shahata El-Sayed KA. Effectof Nd: YAG laser capsulotomy size on visual outcomes of the eye, intraocular pressure, and macular thickness. Menoufia Med J [serial online] 2017 [cited 2019 Aug 24];30:512-6. Available from: http://www.mmj.eg.net/text.asp?2017/30/2/512/215453


  Introduction Top


Posterior capsule opacification(PCO) is still the most common problem following cataract surgery[1], and it results from the proliferation and migration of residual lenticular epithelial cells[2]. Neodymium:yttrium–aluminum–garnet (Nd:YAG) laser capsulotomy is the standard treatment for PCO[3]. Although Nd:YAG laser capsulotomy has been found to be safe and effective, events such as intraocular lens(IOL) dislocation leading to hyperopia, IOL subluxation or luxation, retinal detachment[4], cystoid macular edema[5], and rise in intraocular pressure(IOP) [6] tend to occur after Nd:YAG laser capsulotomy.

Optical and mechanical factors should be considered for the optimal size of the posterior capsulotomy. Optical factors include diffraction, reduced image sensitivity, and glare. The optical considerations favor a large capsulotomy size. Mechanical considerations are based on the barrier effect of the intact posterior capsule and favor a small capsulotomy size[7]. Holladay etal.[7] concluded that the optimal capsulotomy size should be equal or should exceed the diameter of the pupil in the scotopic conditions and remain within the border of the IOL.

Macular edema is caused by movement and damage in the vitreous cavity and release of inflammatory mediators because of the damage of blood–aqueous barrier, as in complicated cataract surgeries with ruptured posterior capsule and vitreous loss, which is considered a risk factor for the development of postoperative macular edema[8]. Elevated IOP is associated with an increased amount of aqueous particles following Nd:YAG laser capsulotomy[9].

Ari etal.[10] underlined that the severity and duration of increased IOP and macular thickness are less when a total energy level less than 80 mJ is used. There is little information about the pure effect of capsulotomy size on IOP and macular thickness when Nd:YAG laser capsulotomy is performed with same energy levels.


  Materials and Methods Top


A total of 56 eyes of 56patients were enrolled in this prospective comparative study. Acomparison was made between group1, which included 28 eyes with capsulotomy size less than 3.9mm, and group2, which included 28 eyes with capsulotomy size equal to or larger than 3.9mm.

All Nd:YAG laser capsulotomies were carried out at the Ophthalmology Department, Menoufia University Hospital, Menoufia Governorate, Egypt, between January 2015 and December 2015 using Ophthalmic Nd:YAG laser (Visulas YAG III; Zeiss, Oberkochen, Germany).

All eyes had PCO following uncomplicated cataract surgery. Patients with corneal opacities, glaucoma, retinopathy, maculopathy, and optic neuropathy, and patients with diabetes mellitus, patients with a past history of uveitis, presence of epiretinal membrane on optical coherence tomography(OCT) preoperatively, and dense PCO precluding preoperative OCT were excluded from this study.

All the pre-Nd:YAG and post-Nd:YAG laser capsulotomy assessments were performed by one ophthalmologist. Assessments included best-corrected visual acuity (BCVA), IOP measurement by Goldmann's applanation tonometry, slit-lamp evaluation, and fundoscopic evaluation and central foveal thickness (CFT) by RS-3000°CT RetinaScan device (NIDEK, Tokyo, Japan), which were performed before the procedure and 1, 4, and 12weeks after Nd:YAG laser capsulotomy. Topical anesthesia was then achieved using benoxinate hydrochloride 0.4% eye drops, and a capsulotomy contactlenses (double aspheric capsulotomy lens; Volk Optical Inc., Mentor, OH) with lubricating gel(methyl cellulose) was used during the capsulotomy; power/energy was initially set between 0.7 and 2.5 mJ–power varied according to how dense the PCO was. The 'golden rule' for any laser is to use the least amount of energy at the lowest settings to get the job done. Our typical starting energy was 0.7 mJ. Spotsize and duration were fixed, meaning that they cannot be altered on a YAG laser; number of pulses per shot was one, which means one pulse of laser energy is fired at the capsule every time the button was pressed; the offset of the laser was set between 125 and 250μm posteriorly; the aiming beam was then focused on the posterior capsule and capsulotomy was performed; and then widening of the capsulotomy openening is eccentrically performed as needed whether small or large sized but still within the edge of the IOL.

All capsulotomies were completed in one session; all patients were prescribed topical prednisolone acetate 1% four times a day and brimonidine tartrate 0.2% twice a day for 1week postoperatively(post laser therapy).

Statistical analysis

These data were tabulated and analyzed using the computer program statistical package for the social science, version16(December 2013, IBM SPSS; IBM, Endicott, NewYork, USA).


  Results Top


As regards age and sex, group1 included 14male(50%) and 14female(50%) patients, with a mean age of 52.54±6.59years(range: 43–72years). Group2 included 15male(54%) and 13female(46%) patients, with a mean age of 58.25±6.14years(range: 49–69years). The difference was not statistically significant(P=0.774; NS).

As regards the capsulotomy size, the mean capsulotomy size in group1 was 3.56±0.28mm and in group2 it was 4.56±0.47mm, and the difference between the two groups was statistically significant, as the P value was 0.001[Table1].
Table 1: Comparison between the two study groups as regards capsulotomy size

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There was a statistically significant improvement in visual acuity(VA) in both groups, with no affection of capsulotomy size on improvement in VA, when comparing the results of BCVA between the two groups at 1, 4, and 12weeks after capsulotomy, and it was statistically nonsignificant with a P value of 0.742 [Table2] and [Table3].
Table 2: Comparison between the two study groups as regards best-corrected visual acuity before capsulotomy

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Table 3: Comparison between the two study groups as regards best-corrected visual acuity at 1, 4, and 12 weeks after capsulotomy

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In both groups, IOP increased 1week after Nd:YAG laser capsulotomy, IOP rise in group2 (mean: 18.96±1.95mmHg) was higher than that in group1(mean: 16.82±1.83mmHg), and it was of statistical significance with a P value of 0.028; there were three(5.4%) patients in group2 with increased IOP ranging between 22 and 24mmHg with an increase of an average of 8mmHg above the preoperative values, whereas in group1 the upper limit of IOP was 18mmHg.

IOP declined to the preoperative levels at 4weeks after Nd:YAG laser capsulotomy in both groups, with a mean of 14.86±1.6mmHg in group1 and a mean of 14.11±159mmHg in group2, which was statistically nonsignificant and remained within this range during the period of follow-up at 4 and 12weeks[Table4].
Table 4: Comparison between the two study groups as regards intraocular pressure before and 1, 4, and 12 weeks after capsulotomy

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Both groups had increased macular thickness at 1week after Nd:YAG laser capsulotomy, with a mean of 260.39±17.35μm in group1 and a mean of 259.75±17.64μm in group2, which is statistically nonsignificant. Mean macular thickness was decreased to preoperative levels at 4weeks after Nd:YAG laser capsulotomy in both groups, with a mean of 251.39±18.66μm in group1 and a mean of 250.79±19.15μm in group2, and at 12weeks with a mean of 240.5±17.71μm in group1 and a mean of 240.75±17.82μm in group2[Table5].
Table 5: Comparison between the two study groups as regards central foveal thickness before and at 1, 4, and 12 weeks after capsulotomy

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  Discussion Top


The main goal of Nd:YAG laser capsulotomy is to improve VA. Smaller capsulotomy openings limit VA by diffraction and result in light passing through the unopened region of the capsule being scattered, causing glare and decreasing contrast sensitivity. Capsulotomy opening should therefore be equal to or larger than the size of the pupil in scotopic conditions[11]. However, capsulotomy openings should be large enough to ensure good visualization of the peripheral fundus, particularly in patients with retinal disease.

With respect to pre-Nd:YAG and post-Nd:YAG laser capsulotomy visual outcome in terms of VA in this study, it was revealed that 60.7% of patients had VA of 6/60 or less before capsulotomy in group1(28 eyes) and 64.3% in group2(28 eyes). The VA after Nd:YAG laser capsulotomy showed improvement by one or more Snellen's lines in 28 out of 28 eyes in each group. VA of 6/18 or better was recorded in 96.4% of eyes in group1 and 96.4% in group2. It was also observed that none of them had further deterioration of VA after Nd:YAG laser capsulotomy, and thus there was no significant effect of capsulotomy size on the improvement in VA.

Cetinkaya etal.[12] examined the effect of Nd:YAG capsulotomy size on VA and refraction, and found two groups: group1(39 eyes), of small capsulotomy size(≤3.5mm), and group2(46 eyes), of large capsulotomy size(>3.5mm). The mean preprocedural BCVA was 0.54±0.22 logMAR units in group1 and 0.51±0.20 logMAR units in group2, and the mean postprocedural BCVA was 0.03±0.06 logMAR units in group1 and 0.02±0.05 logMAR units in group2. There was no statistically significant effect of capsulotomy size on refraction or improvement in VA in any groups following Nd:YAG laser capsulotomy, which correlates with the results of the current study.

Yilmaz etal.[13] found the change in spherical equivalent refraction to be 0.38±0.52 D in the small capsulotomy group and 0.22±0.36 D in the large capsulotomy group, and no statistically significant differences were noted in spherical equivalent refraction change(P=0.47) between the two groups, and the size of posterior capsulotomy did not significantly affect refraction and the improvement in VA, which correlates with the results of the current study.

In the current study, the mean preoperative IOP in group1 was 14.57±1.97mmHg and in group2 it was 14.54±2.01mmHg; after 1week of Nd:YAG laser posterior capsulotomy, the mean IOP was increased in both groups(in group1 it was 16.82±1.83mmHg and in group2 it was 18.96±1.95mmHg), the rise of IOP was higher in the large capsulotomy group when compared with the rise in IOP in the small capsulotomy group, and it was of statistical significance.

After 4weeks of Nd:YAG laser posterior capsulotomy, the mean IOP decreased in both groups(in group1 it was 14.86±1.6mmHg and in group2 it was 14.11±1.59mmHg); after 12weeks of Nd:YAG laser posterior capsulotomy, the mean IOP in group1 and in group2 was decreased nearly to the preoperative values.

Cetinkaya etal.[12] examined the effect of Nd:YAG laser posterior capsulotomy size on IOP after 1month, and the mean preprocedural IOP in the group of small capsulotomy size(≤3.5mm) was 15.31±3.59mmHg and in the large capsulotomy size group(>3.5mm) it was 15.43±1.94mmHg. The mean postprocedural IOP was 14.65±2.56mmHg in the group of small capsulotomy size and was 15.34±1.96mmHg in the group of large capsulotomy size, and there was no statistically significant effect of capsulotomy size on IOP at 1month after the Nd:YAG laser posterior capsulotomy, which correlates with the results of the current study.

Karahan etal.[14] assessed the effect of Nd:YAG laser posterior capsulotomy size on IOP, at 1, 4, and 12weeks, and the mean preprocedural IOP in the group of small capsulotomy size(3.43±0.34mm) was 15.44±2.73mmHg and in the group of large capsulotomy size(4.56±0.47mm) it was 15.37±3.61mmHg. After 1week of Nd:YAG laser posterior capsulotomy, there was a statistically significant increase in IOP in both groups and the mean IOP in the group of small capsulotomy size was 16.33±2.42mmHg and in the group of large capsulotomy size it was 17.40±3.26mmHg, and the rise of IOP was higher in the large capsulotomy group when compared with that of the small capsulotomy group, as more capsule particles released with larger capsulotomies might be the reason of higher rates of elevation of IOP in the group of large capsulotomies. After 4weeks of Nd:YAG laser posterior capsulotomy, the mean IOP decreased in both groups(in the group of small capsulotomy size it was 15.13±2.68mmHg and in the group of large capsulotomy size it was 15.25±3.95mmHg). After 12weeks of Nd:YAG laser posterior capsulotomy, the mean IOP in the group of small capsulotomy size was 14.83±2.10mmHg and in the group of large capsulotmy size it was 15.71±2.30mmHg. The mean IOP levels were significantly higher at 1week than preoperative levels in both groups; IOP levels declined to the preoperative levels at 4 and 12weeks, which correlates with the results of the current study.

However, Shani etal.[15] could not find any elevation of IOP after Nd:YAG laser posterior capsulotomy and postulated that healthy pseudophakic eyes do not generally show elevation of IOP after Nd:YAG laser capsulotomy, and Ari etal. [10] also did not find any persistent rise in IOP.

In the current study, we measured the CFT before YAG laser capsulotomy and in group1 it was 238.64±19.74μm and in group2 it was 240.39±20.9μm; there was a statistically significant increase in CFT after 1week in both groups(CFT in group1 was 260.39±17.35μm and in group2 it was 259.75±17.64μm). The mean macular thicknesses were decreased postoperatively at 4weeks(CFT in group1 was 251.39±18.66μm and in group2 it was 250.79±19.15μm) and at 12weeks(CFT in group1 was 240.5±17.71μm and in group2 was 240.75±17.82μm), when comparing the results between the two groups with respect to macular thickness, and there was no statistically significant effect of capsulotomy size on the increased CFT at 1, 4, or 12weeks postoperatively.

Karahan etal.[14], examined the effect of Nd:YAG laser capsulotomy size on CFT. The mean preprocedural CFT in the group of small capsulotomy size(3.43±0.34mm) was 247.5±31.3μm and in the group of large capsulotomy size(4.56±0.47mm) it was 244.5±37.2μm; after 1week of Nd:YAG laser posterior capsulotomy, the mean CFT was increased in both groups and in group of small capsulotomy it was 262.8±27.2μm and in the group of large capsulotomy it was 259.9±24.9μm. The mean CFT decreased in both groups4weeks after capsulotomy, and it was 247.3±36.8μm in the group of small capsulotomy and 246.7±32.5μm in the group of large capsulotomy, and 12weeks after capsulotomy it was 246.0±29.6μm in the group of small capsulotomy and 242.9±28.7μm in the group of large capsulotomy. He found that there was no significant effect of capsulotomy size on CFT, which correlates with the results of the current study.

In addition, Ari etal. [10] found that an increase in macular thickness is inevitable after Nd:YAG laser capsulotomy, but the severity and duration are less when a total energy level less than 80 mJ is used but he did not assess the effect of capsulotomy size on CFT.


  Conclusion Top


In this study, we concluded that patients who underwent Nd:YAG laser capsulotomy have significant improvement in VA regardless of the capsulotomy size, and larger capsulotomies have a higher IOP elevation probably because of the increased release of inflammatory products. However, macular thickness was the same in large and small capsulotomy groups. Our treatment strategy and recommendation is that the capsulotomy opening should therefore be equal to or larger than the size of the pupil in scotopic conditions(3.9±0.5mm).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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AslamTM, DevlinH, DhillonB. Use of Nd:YAG laser in capsulotomy. Surv Ophthalmol 2003; 48:594–612.  Back to cited text no. 1
    
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SteinertRF, PuliafitoCA, KumarSR, DudakSD, PatelS. Cystoid macular oedema, retinal detachment and glaucoma after Nd:YAG laser posterior capsulotomy. Am J Ophthalmol 1991; 112:373–380.  Back to cited text no. 4
    
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ShahGR, GillsJP, DurhamDG, AusmusWH. Three thousands YAG laser posterior capsulotomies: an analysis of complications and comparison to polishing and surgical decision. Ophthalmic Surg 1986; 17:473–477.  Back to cited text no. 5
    
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ChannellMM, BeckmanH. Intraocular pressure changes after neodymium YAG laser posterior capsulotomy, Arch Ophthalmol 1984; 102:1024–1026.  Back to cited text no. 6
    
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HolladayJT, BishopJE, LewisJW. The optimal size of a posterior capsulotomy. JAm Intraocul Implant Soc 1985; 11:18–20.  Back to cited text no. 7
    
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El-Sebaey SarhanA, El MorsyOA, Abdallah AbdallahMG. Macular thickness analysis following complicated versus uncomplicated cataract surgery using optical coherence tomography. Menouf Med J 2015; 28:184–190.  Back to cited text no. 8
    
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AriS, Cingü AK, SahinA, Çinar Y, Çaça I. The effects of Nd:YAG laser posterior capsulotomy on macular thickness, intraocular pressure, and visual acuity. Ophthalmic Surg Lasers Imaging 2012; 43:395–400.  Back to cited text no. 10
    
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NadlerDJ, JaffeNS, Clayman HM Glare disability in eyes with intraocular lenses. Am J Ophthalmol 1984; 97:43–47.  Back to cited text no. 11
    
12.
CetinkayaS, CetinkayaYF, YenerHI, DadaciZ, OzcimenM, AcirNO. The influence of size and shape of Nd:YAG laser capsulotomy on visual acuity and refraction. Arq Bras Oftalmol. 2015; 78:220–223.  Back to cited text no. 12
    
13.
YilmazS, OzdilMA, BozkirN, MadenA. The effect of Nd:YAG laser capsulotomy size on refraction and visual acuity. JRefract Surg 2006; 22:719–721.  Back to cited text no. 13
    
14.
KarahanE, TuncerI, ZenginMO. The effect of Nd:YAG laser posterior capsulotomy size on refraction, intraocular pressure and macular thickness. JOphthalmol. 2014; 846385:5.  Back to cited text no. 14
    
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ShaniL, DavidR, TesslerZ, RosenS, SchneckM, YassurY. Intraocular pressure after neodymium YAG laser treatments in the anterior segment. JCataract Refract Surg 1994; 20:455–458.  Back to cited text no. 15
    



 
 
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