- Email: [email protected]
Posterior capsule opacification rate after phacoemulsification in pediatric cataract: Hydrophilic versus hydrophobic intraocular lenses
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ARTICLE
Posterior capsule opacification rate after phacoemulsification in pediatric cataract: Hydrophilic versus hydrophobic intraocular lenses Pradhnya Sen, MB BS, MS, Mansi Kshetrapal, MB BS, DOMS, Chintan Shah, MB BS, DOMS, Amit Mohan, MB BS, MS, Elesh Jain, MB BS, DOMS, DNB, Alok Sen, MB BS, MS
Purpose: To compare the rate of posterior capsule opacification (PCO) of hydrophilic acrylic intraocular lenses (IOLs) and hydrophobic acrylic IOLs in pediatric cataract surgery. Setting: Sadguru Netra Chikitsalaya, Chitrakoot, India. Design: Retrospective case series. Methods: The medical records of children who had uneventful cataract surgery with acrylic IOL implantation from 2010 to 2016 and a follow-up of at least 1-year were reviewed. The patients had implantation of a hydrophilic IOL (Ocuflex ANU6 IOL) or a hydrophobic IOL (AcrySof SA60AT). The main outcome measure was the PCO rate at the last follow-up. Results: The study comprised 103 eyes (80 children). The mean age was 8.2 years G 4 (SD) in the hydrophilic group (51 eyes) and 6.9 G 4 years in the (52 eyes) hydrophobic group (P Z .1). The
P
ediatric cataract is a significant cause of preventable blindness and visual impairment in children. It is responsible for 5% to 20% of childhood blindness worldwide.1 The prevalence of cataract is 1 to 2 per 10 000 live births in developed countries. In developing countries, it is approximately 10 per 10 000 live births, which is almost 10 times higher than in developed countries.2 This high prevalence of pediatric cataract is a major challenge in developing countries. Other common challenges in our geographic area are delayed presentation and late surgical intervention resulting from low socioeconomic status and lack of awareness.3 In a resource-poor setting, socioeconomic status also plays a detrimental role in the type of surgery performed and in the choice of intraocular lens (IOL).
mean follow-up was 38.8 months and 39.4 months, respectively. When the posterior capsule was left intact, 39.3% of eyes in the hydrophilic group and 13.4% of eyes in the hydrophobic group developed PCO (P Z .03). When primary posterior capsulotomy (PPC) and anterior vitrectomy were performed, 4.3% and 6.8%, respectively, developed PCO (P Z .69). Kaplan-Meier survival plots with stratification for type of procedure (ie, PPC and anterior vitrectomy) showed a survival (ie, no PCO formation at 5-year follow-up) rate of 95.4% in the hydrophobic group and 88.8% in the hydrophilic group.
Conclusion: Hydrophilic acrylic IOLs and hydrophobic acrylic IOLs implanted in the bag had comparable visual and surgical outcome and an equal rate of PCO formation when PPC and anterior vitrectomy were performed. J Cataract Refract Surg 2019; 45:1380–1385 Q 2019 ASCRS and ESCRS
Management of visually significant cataract in children is surgical. Lens aspiration with intraocular lens (IOL) implantation has become the standard of care worldwide. In addition to IOL power calculation, the IOL material remains an issue in this population. Today, the most commonly used IOLs in pediatric cataract are acrylic hydrophobic because of the material’s capsule biocompatibility. However, the cost of these IOLs limit their use in a developing country.3 In rural areas, we implant hydrophilic acrylic IOLs in almost equal proportion to hydrophobic acrylic IOLs because they are more affordable for patients. Although many studies have evaluated poly(methyl methacrylate), silicone, hydrophobic, and hydrophilic acrylic IOLs in pediatric cataract patients,4–7 to our knowledge none has compared hydrophilic IOLs and hydrophobic IOLs in
Submitted: February 4, 2019 | Final revision submitted: April 2, 2019 | Accepted: May 12, 2019 From the Children’s Eye Care Center (P. Sen), Pediatric Ophthalmology and Strabismus (Kshetrapal, Shah, Mohan, Jain), and the Department of Retina and Uvea (A. Sen), Sadguru Netra Chikitsalaya, Chitrakoot, Madhya Pradesh, India. Corresponding author: Pradhnya Sen, MB BS, MS, Sadguru Netra Chikitsalaya, Chitrakoot, Jankikund, District Satna, Madhya Pradesh-210204, India. Email: [email protected]. Q 2019 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter https://doi.org/10.1016/j.jcrs.2019.05.018
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this population. In this retrospective study, we compared the visual outcomes and complications after primary in-the-bag implantation of foldable hydrophilic acrylic IOLs and foldable hydrophobic acrylic IOLs in pediatric eyes. PATIENTS AND METHODS This retrospective review comprised the records of patients who had primary lens aspiration with in-the-bag implantation of a hydrophobic or hydrophilic foldable acrylic IOL from 2010 to 2016. The study included patients from 0 to 18 years of age with unilateral or bilateral congenital or developmental cataract and a minimum follow-up of 1 year. The study was approved by an institutional review board and performed in accordance with the tenets of the Declaration of Helsinki. Exclusion criteria were cataracts associated with other ocular abnormalities (microphthalmos, microcornea, glaucoma, uveitis, coloboma) or systemic disease, traumatic or complicated cataracts, intraoperative complications, and IOL placement outside the bag. In addition, patients with a follow-up of less than 1 year were excluded from the study. The children were divided into 2 groups based on the type of IOL to be implanted; that is, hydrophilic acrylic (hydrophilic group) or hydrophobic acrylic (hydrophobic group). Preoperatively, the child’s parents or guardians were counseled on the surgical procedure and IOL implantation and the pros and cons of the IOL material. They chose the type of IOL to be implanted based on affordability; however, implantation of the hydrophilic IOL and the hydrophobic IOL was almost equally distributed throughout the study period. Preoperative Evaluation All patients had a detailed preoperative evaluation. The vision of uncooperative children was assessed using the central, steady, and maintained fixation method. Visual acuity was evaluated with age-appropriate visual acuity testing charts (eg, Lea grating paddles, Teller acuity) in preverbal children and with a Snellen chart in older children. Intraocular pressure was measured using noncontact tonometry or applanation tonometry depending on cooperation of the child. An anterior segment examination was performed at the slitlamp or under the operating microscope.
The posterior segment was examined using indirect ophthalmoscopy or B-scan ultrasonography if the media was opaque. Biometric measurements were performed using conventional keratometry in cooperative children or a handheld autokeratometer under general anesthesia in smaller children. The axial length was measured with an immersion technique using A-scan ultrasonography or a contact technique under anesthesia. Intraocular lens power was calculated using the SRK II formula8 in all cases. Although the SRK II is an older formula, it continues to be used at the institution because it has given consistently good results. In addition, some authors have used this formula in pediatric cataract surgery.4,5 The power was adjusted in children younger than 8 years using Dahan and Drusedau’s formula9 according to the patient’s age. Surgical Technique All surgeries were performed by experienced pediatric ophthalmologists (P.S., C.S., A.M., E.J.) using local anesthesia or general anesthesia, with the choice of anesthesia based on the age of the patient. The surgeons did not have a preference for which surgical technique to use or which IOL (hydrophilic or hydrophobic) to implant. The lens matter was aspirated using a phacoaspiration and/or a bimanual irrigation/aspiration cannula. A foldable acrylic hydrophilic IOL (Ocuflex ANU6, Care Group) or hydrophobic IOL (AcrySof SA60AT, Alcon Laboratories, Inc.) was implanted in the capsular bag. Primary posterior capsulorhexis with anterior vitrectomy was performed before or after IOL implantation in children younger than 8 years, those with mental disabilities, or those who had nystagmus or poor fixation. All patients received topical prednisolone 1.0% eyedrops 8 times a day in a tapering dose for 6 weeks as well as topical moxifloxacin 0.5% eyedrops 4 times a day and homatropine 2.0% eyedrops 2 times a day for 2 weeks. Postoperative Evaluation Visual acuity, refraction, corrected distance visual acuity (CDVA), and intraocular pressure measurements were assessed postoperatively at 1 day, 1 month, 6 months, and 1 year. Outcome measures included postoperative complications such as anterior chamber inflammation, pigment over the IOL, fibrinous membrane, and posterior capsule opacification (PCO). Posterior capsule opacification was defined as any central whitening or wrinkling of the
Table 1. Patient demographics by group. Parameter Sex (n) Male Female Age (y) 0–2 (n) 3–8 (n) 9–18 (n) Mean Eye (n) Right Left Nystagmus Strabismus Mean AL (mm) Mean IOL power (D) Follow-up (m) Mean Range
Hydrophilic Acrylic (51 Eyes)
Hydrophobic Acrylic (52 Eyes)
35 16
38 14
8 22 21 8.2 G 4.0
10 28 14 6.9 G 4.0
P Value .97
25 26 3 1 22.05 22.6 38.8 G 21.6 12, 84
24 28 2 3 21.50 23.00 39.4 G 20.8 12, 84
.1 .8
d d .9 .9 .8
Means G SD AL Z axial length; IOL Z intraocular lens
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Table 2. Comparison of PCO formation in eyes in which PPV and anterior vitrectomy were performed. Number (%) PCO Type
Hydrophilic IOL (n Z 23)
Hydrophobic IOL (n Z 29)
P Value
1 (4.3) 0 1 (4.3)
2 (6.8) 0 2 (6.8)
.69 d .69
Visually significant Visually insignificant Total incidence
IOL Z intraocular lens; PCO Z posterior capsule opacification; PPC Z primary posterior capsulorhexis
posterior lens capsule on slitlamp examination.10 Visually significant PCO was defined as a decrease of 2 or more lines from the postoperative CDVA or when retinoscopy or fundoscopy was not possible.11 Spectacles were prescribed at 1 month, and amblyopia therapy (ie, patching) was started when needed. Statistical Analysis Descriptive statistical analyses were performed on categorical measurements using SPSS for Windows software (version 16.0, SPSS, Inc.); the results are presented as the number (percentage) or as the mean G SD. The results were analyzed using GraphPad Prism for Windows software (version 7.00, GraphPad Software, Inc.).A The unpaired t test was used to compare the mean values in the 2 IOL groups. Comparative analysis of the 2 IOLs was performed using a contingency data table. The relative risk was calculated using the Koopman asymptotic score. The Fischer exact test was used to compare the rate of PCO formation between the 2 groups. A P value less than 0.05 was considered statistically significant. Kaplan-Meier probability curves were used to calculate the risk for developing PCO at a given interval after surgery. The Gehan-BreslowWilcoxon test and log-rank (Mantel-Cox) test tables were used to analyze the difference in probability curves between the 2 IOL groups.
RESULTS Eighty patients (103 eyes) met the inclusion criteria and were included in the study. Of the 80 patients, 53 were boys and 27 were girls. Lens matter aspiration with IOL implantation was performed in 51 eyes (28 hydrophilic group; 23 hydrophobic group); primary posterior capsulotomy (PPC) and anterior vitrectomy were also performed in 52 eyes (23 hydrophilic group; 29 hydrophobic group). Twenty-seven eyes (26.2%) had congenital cataract, and 76 eyes (73.8%) had developmental cataract. Table 1 shows the patients’ demographics and associated ocular morbidities. There were no significant differences in preoperative characteristics between the hydrophilic group and the hydrophobic group. The preoperative CDVA ranged from fixing and following light to 20/40 in both groups; 18 eyes (17.5%) had a CDVA of 20/200 or better. Postoperatively, 37 eyes
(72.5%) in the hydrophilic group and 39 eyes (75.0%) in the hydrophobic group had a CDVA of 20/40 or better; the difference between groups was not significant (P O .05). In both groups, 18 eyes were amblyopic and received amblyopia therapy. Postoperatively, no eye had an anterior chamber reaction of grade 2 or higher. In all cases, the reaction resolved with topical medications in 4 to 6 weeks. There were no cases of pigment over the IOL, IOL decentration, wound leak, or endophthalmitis. The most common complication was PCO, occurring in 30 of 103 eyes as of the last follow-up. Tables 2 and 3 and Figure 1 show the number of eyes with PCO in each IOL group by surgical technique. The rate was higher in eyes that did not have PPC and anterior vitrectomy. In eyes having PPC and anterior vitrectomy, there was no significant difference in the rate of PCO between the 2 IOL groups (P Z .69). Figure 2 shows 5-year postoperative slitlamp images of a clear visual axis (ie, no PCO) in eyes with a PPC and anterior vitrectomy. In eyes in which PPC and anterior vitrectomy were not performed, the hydrophilic group was at risk for developing visually significant PCO earlier than the hydrophobic group. However, long-term analysis of the total PCO rate found no statistically significant difference between the 2 groups (P Z .5). Of the 17 eyes with visually significant PCO, 15 (11 hydrophilic group; 4 hydrophobic group) had a Nd:YAG capsulotomy. Membranectomy was performed in 1 eye in each group. The mean follow-up duration after Nd:YAG capsulotomy and membranectomy was 3.2 years. No complications (eg, IOL pitting, retinal detachment, cystoid macular edema) were seen in any eye having these procedures. Figures 3 and 4 show the Kaplan-Meier survival plots for eyes that developed PCO (visually significant and insignificant); the length of the blue curves and red curves were
Table 3. Comparison of PCO formation in eyes in which PPV and anterior vitrectomy were not performed. Number (%) PCO Type
Hydrophilic IOL (n Z 28)
Hydrophobic IOL (n Z 23)
P Value
11 (39.3) 5 (17.8) 16 (57.1)
3 (13.4) 8 (34.7) 11 (47.8)
.03* .16 .5
Visually significant Visually insignificant Total incidence
IOL Z intraocular lens; PCO Z posterior capsule opacification; PPC Z primary posterior capsulorhexis *Relative risk of 4.5 for significant PCO formation in hydrophilic group
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Figure 1. Number of eyes with PCO by intraocular lens group and surgical technique (PCO Z posterior capsule opacification; PPC Z primary posterior capsulotomy).
not identical because of variable follow-up times. The 3year cumulative incidence of no PCO formation was 80.8% (42 eyes) in the hydrophobic group and 70.6% (36 eyes) in the hydrophilic group. The survival rate (ie, no PCO formation at 5-year follow-up) when PPC and anterior vitrectomy were performed was 93.1% (27 eyes) in the hydrophobic group and 95.6% (22 eyes) in the hydrophilic group; the difference was not statistically significant (P Z .4; Mantel-Cox test). DISCUSSION Posterior capsule opacification is the most common complication of pediatric cataract surgery and occurs in almost all cases if the posterior capsule is left intact.12 The rate of PCO decreases with advancing age.13–15 If PCO obscures the visual axis, it is as amblyogenic as the cataract itself.14 However, advances in IOL material, IOL edge design, and surgical technique have helped minimize the rate of PCO formation.16 The rate of PCO is markedly reduced when PPC and anterior vitrectomy are performed.15 In most cataract surgery techniques, small incisions are created; thus, foldable acrylic (hydrophobic or hydrophilic) IOLs have become the preferred choice. Hydrophobic IOLs reduce the rate of PCO because they adhere to the collagen membrane, leading to tight apposition of IOLs to the posterior capsule. This results in less space between the IOL and the posterior capsule through which lens epithelial cells can migrate.17,18 However, these IOLs are expensive; therefore,
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acrylic hydrophilic IOLs are often used rather than hydrophobic IOLs in developing countries. Hydrophilic IOLs have excellent uveal biocompatibility but lower capsule biocompatibility.19 The choice of IOL in our study was dependent on how much the parents or guardians could afford. To our knowledge, no previous study has compared hydrophilic IOLs and hydrophobic IOLs in the pediatric cataract population. In a study of 120 patients by Kugelberg et al.,20 18.6% of eyes with hydrophilic IOLs and 4.0% of eyes with hydrophobic IOLs developed PCO. However, their patients were adults and thus had a lower PCO rate than our pediatric cohort (17 [33.3%] of 51 eyes and 13 [25.0%] of 52 eyes, respectively). In addition, the PCO rate was followed for 1 year only in the Kugelberg et al. study. In a study of hydrophilic IOL implantation in pediatric eyes with cataract by Adhikari and Shrestha,3 7% of eyes developed PCO over a mean follow-up of 13.7 months. This is significantly less than the incidence in our study (33.3 %), which might be the result of the much longer follow-up (38.8 months) of our patients. In our study, the PCO rate in eyes in the hydrophobic group that had PPC and anterior vitrectomy (6.8%) is comparable to that in other studies. In a study by Ram et al.,21 13.3% of eyes in which hydrophobic IOLs were implanted using a similar surgical approach developed PCO. The rate of PCO was 10.8% in a study by Vasavada et al.7 Aasuri et al.4 found visually significant opacification in 21.05% of eyes with hydrophobic IOLs when the posterior capsule was left intact. In the present study, the rate of PCO was 13.4% in eyes in which the posterior capsule was left intact. The lower incidence in our study might have been the result of our strict criteria, which excluded complicated cataract cases and surgeries. When PPC and anterior vitrectomy were performed, the PCO rate was 4.3% in the hydrophilic group and 6.8% in the hydrophobic group. The difference was not significant, showing that when PPC and anterior vitrectomy are performed and the IOL is implanted in the bag, the IOL material does not affect the outcomes. The incidence of visually significant PCO was statistically significantly higher in the hydrophilic group when PPC and anterior vitrectomy were not performed (P Z .03). However, the overall PCO rate was comparable in the 2 IOL
Figure 2. Five-year postoperative slitlamp images of clear visual axis (ie, no posterior capsule opacification) in an eye with a hydrophilic IOL (a) and an eye with a hydrophobic IOL (b). Both eyes had primary posterior capsulotomy and anterior vitrectomy (IOL Z intraocular lens).
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Figure 3. Kaplan-Meier survival plots for eyes in which primary posterior capsulotomy and anterior vitrectomy were not performed (IOL Z intraocular lens).
groups, as shown by the Kaplan-Meier survival curves (Figure 3). Eyes with significant PCO had an Nd:YAG capsulotomy (15 eyes) or membranectomy (2 eyes). Neodymium:YAG capsulotomy is easier to perform in older children because in general they are cooperative during outpatient procedures. No complications, such as IOL pitting, occurred in any eye having a capsulotomy; the damage threshold for acrylic IOLs during Nd:YAG laser capsulotomy is comparable to that for silicone or poly(methyl methacrylate) IOLs.22 Other complications, such as a spike in intraocular pressure, retinal detachment, or cystoid macular edema, were not reported as of the last follow-up examination. Postoperatively, 72.5% in the hydrophilic group and 75.0% in the hydrophobic group had a CDVA of 20/40 or better. In studies by Adhikari and Shrestha3 and Aasuri et al.,4 the visual acuity was 20/40 or better in 44.5% of eyes and 60.8% of eyes, respectively. Our results were better because our study included a higher proportion of eyes with developmental cataract, for which the prognosis is likely better. In our study, the postoperative visual outcomes were comparable between hydrophilic IOLs and hydrophobic IOLs. The rate of significant PCO formation was higher in the hydrophilic group when the posterior capsule was left intact. When PPC and anterior vitrectomy were performed, the results were comparable between the 2 IOL types. The PCO was successfully treated with Nd:YAG capsulotomy with no long-term adverse events, such as reopacification. A strength of our study is that we included only eyes with developmental or congenital cataract in which the IOL was implanted in the bag. This allowed us to make a valid comparison of the 2 IOL materials. A major limitation of our study is its retrospective nature. Also, the choice of the IOL to be implanted depended on how much the parent or guardian could afford to pay. To avoid potential bias, prospective studies with random allocation to the 2 groups should be performed. In conclusion, when PPC and anterior vitrectomy were performed, the PCO rates were low and the material of Volume 45 Issue 10 October 2019
Figure 4. Kaplan-Meier survival plots for eyes in which PPC and anterior vitrectomy were performed (IOL Z intraocular lens; PPC Z primary posterior capsulotomy).
the IOL did not affect the outcomes. In cases in which the posterior capsule was left intact, eyes with hydrophilic IOLs had a higher incidence of visually significant PCO. However, the PCO was treated with Nd:YAG capsulotomy without complications. Thus, hydrophilic IOLs can be a good alternative to hydrophobic IOLs when the patient’s ability to afford more expensive IOLs is a major concern.
WHAT WAS KNOWN Hydrophobic acrylic intraocular lenses (IOLs) are the preferred IOL in pediatric cataracts. Foldable hydrophilic IOLs are safe to use in children.
WHAT THIS PAPER ADDS The surgical technique (primary posterior capsulotomy and anterior vitrectomy) was more important than the IOL material in posterior capsule opacification (PCO) formation. Nd:YAG laser capsulotomy was successful in treating PCO in older children without long-term complications.
REFERENCES 1. Gilbert C, Foster A. Childhood blindness in the context of vision 2020 d the right to sight. Bull World Health Organ 2001; 79:227–232 2. Foster A, Gilbert C, Rahi J. Epidemiology of cataract in childhood: a global perspective. J Cataract Refract Surg 1997; 23:601–604 3. Adhikari S, Shrestha UD. Pediatric cataract surgery with hydrophilic acrylic intraocular lens implantation in Nepalese children. Clin Ophthalmol 2018; 12:7–11 4. Aasuri MK, Fernandes M, Pathan PP. Comparison of acrylic and polymethyl methacrylate lenses in a pediatric population. Indian J Ophthalmol 2006; 54:105–109 5. Bhusal S, Ram J, Sukhija J, Pandav SS, Kaushik S. Comparison of the outcome of implantation of hydrophobic acrylic versus silicone intraocular lenses in pediatric cataract: prospective randomized study. Can J Ophthalmol 2010; 45:531–536 6. Ram J, Kaushik S, Brar GS, Gupta A. Neodymium:YAG capsulotomy rates following phacoemulsification with implantation of PMMA, silicone, and acrylic intraocular lenses. Ophthalmic Surg Lasers 2001; 32:375–382 7. Vasavada AR, Trivedi RH, Nath VC. Visual axis opacification after Arcysof intraocular lens implantation in children. J Cataract Refract Surg 2004; 30:1073–1081; erratum, 1826 8. Sanders DR, Retzlaff J, Kraff MC. Comparison of the SRK IIÔ formula and other second-generation formulas. J Cataract Refract Surg 1988; 14:136–141 9. Dahan E, Drusedau MUH. Choice of lens and dioptric power in pediatric pseudophakia. J Cataract Refract Surg 1997; 23:618–623
PCO FORMATION IN HYDROPHILIC VS HYDROPHOBIC IOLS IN PEDIATRIC CATARACT
10. Rajavi Z, Mokhtari S, Sabbaghi H, Yaseri M. Long-term visual outcome of congenital cataract at a tertiary referral center from 2004 to 2014. J Curr Ophthalmol 2015; 27:103–109 11. Pande MV, Ursell PG, Spalton DJ, Heath G, Kundaiker S. High-resolution digital retroillumination imaging of the posterior lens capsule after cataract surgery. J Cataract Refract Surg 1997; 23:1521–1527 12. Lim ME, Buckley EG, Prakalapakorn SG. Update on congenital cataract surgery management. Curr Opin Ophthalmol 2017; 28:87–92 13. Trivedi RH, Wilson ME, Vasavada AR, Shah SK, Vasavada V, Vasavada VA. Visual axis opacification after cataract surgery and hydrophobic acrylic intraocular lens implantation in the first year of life. J Cataract Refract Surg 2011; 37:83–87 14. Hayashi H, Hayashi K, Nakao F, Hayashi F. Quantitative comparison of posterior capsule opacification after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation. Arch Ophthalmol 1998; 116:1579–1582 15. Vasavada A, Desai J. Primary posterior capsulorhexis with and without anterior vitrectomy in congenital cataracts. J Cataract Refract Surg 1997; 23:645–665 16. Ram J, Brar GS, Kaushik S, Gupta A, Gupta A. Role of posterior capsulotomy with vitrectomy and intraocular lens design and material in reducing posterior capsule opacification after pediatric cataract surgery. J Cataract Refract Surg 2003; 29:1579–1584 17. Buehl W, Findl O. Effect of intraocular lens design on posterior capsule opacification. J Cataract Refract Surg 2008; 34:1976–1985 18. Buehl W, Findl O, Menapace R, Sacu S, Kriechbaum K, Koeppl C, Wirtitsch M. Long-term effect of optic edge design in an acrylic intraocular lens on posterior capsule opacification. J Cataract Refract Surg 2005; 31:954–961 19. Kleinmann G, Zaugg B, Apple DJ, Bleik J. Pediatric cataract surgery with hydrophilic acrylic intraocular lens. J AAPOS 2013; 17:367–370
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€m C. Posterior capsule 20. Kugelberg M, Wejde G, Jayaram H, Zetterstro opacification after implantation of a hydrophilic or a hydrophobic acrylic intraocular lens; one-year follow-up. J Cataract Refract Surg 2006; 32:1627–1631 21. Ram J, Brar GS, Kaushik S, Sukhija J, Bandyopadhyay S, Gupta A. Primary intraocular lens implantation in the first two years of life: safety profile and visual results. Indian J Ophthalmol 2007; 55:185–189 22. Trinavarat A, Atchaneeyasakul L, Udompunturak S. Neodymium:YAG laser damage threshold of foldable intraocular lenses. J Cataract Refract Surg 2001; 27:775–780
OTHER CITED MATERIAL A. GraphPad Software. Introducing Prism8. Available at: https://www .graphpad.com/scientific-software/prism. Accessed June 27, 2019
Disclosures: None of the authors has a financial or proprietary interest in any material or method mentioned.
First author: Pradhnya Sen, MB BS, MS Children’s Eye Care Center, Sadguru Netra Chikitsalaya, Chitrakoot, India
Volume 45 Issue 10 October 2019
ARTICLE
Posterior capsule opacification rate after phacoemulsification in pediatric cataract: Hydrophilic versus hydrophobic intraocular lenses Pradhnya Sen, MB BS, MS, Mansi Kshetrapal, MB BS, DOMS, Chintan Shah, MB BS, DOMS, Amit Mohan, MB BS, MS, Elesh Jain, MB BS, DOMS, DNB, Alok Sen, MB BS, MS
Purpose: To compare the rate of posterior capsule opacification (PCO) of hydrophilic acrylic intraocular lenses (IOLs) and hydrophobic acrylic IOLs in pediatric cataract surgery. Setting: Sadguru Netra Chikitsalaya, Chitrakoot, India. Design: Retrospective case series. Methods: The medical records of children who had uneventful cataract surgery with acrylic IOL implantation from 2010 to 2016 and a follow-up of at least 1-year were reviewed. The patients had implantation of a hydrophilic IOL (Ocuflex ANU6 IOL) or a hydrophobic IOL (AcrySof SA60AT). The main outcome measure was the PCO rate at the last follow-up. Results: The study comprised 103 eyes (80 children). The mean age was 8.2 years G 4 (SD) in the hydrophilic group (51 eyes) and 6.9 G 4 years in the (52 eyes) hydrophobic group (P Z .1). The
P
ediatric cataract is a significant cause of preventable blindness and visual impairment in children. It is responsible for 5% to 20% of childhood blindness worldwide.1 The prevalence of cataract is 1 to 2 per 10 000 live births in developed countries. In developing countries, it is approximately 10 per 10 000 live births, which is almost 10 times higher than in developed countries.2 This high prevalence of pediatric cataract is a major challenge in developing countries. Other common challenges in our geographic area are delayed presentation and late surgical intervention resulting from low socioeconomic status and lack of awareness.3 In a resource-poor setting, socioeconomic status also plays a detrimental role in the type of surgery performed and in the choice of intraocular lens (IOL).
mean follow-up was 38.8 months and 39.4 months, respectively. When the posterior capsule was left intact, 39.3% of eyes in the hydrophilic group and 13.4% of eyes in the hydrophobic group developed PCO (P Z .03). When primary posterior capsulotomy (PPC) and anterior vitrectomy were performed, 4.3% and 6.8%, respectively, developed PCO (P Z .69). Kaplan-Meier survival plots with stratification for type of procedure (ie, PPC and anterior vitrectomy) showed a survival (ie, no PCO formation at 5-year follow-up) rate of 95.4% in the hydrophobic group and 88.8% in the hydrophilic group.
Conclusion: Hydrophilic acrylic IOLs and hydrophobic acrylic IOLs implanted in the bag had comparable visual and surgical outcome and an equal rate of PCO formation when PPC and anterior vitrectomy were performed. J Cataract Refract Surg 2019; 45:1380–1385 Q 2019 ASCRS and ESCRS
Management of visually significant cataract in children is surgical. Lens aspiration with intraocular lens (IOL) implantation has become the standard of care worldwide. In addition to IOL power calculation, the IOL material remains an issue in this population. Today, the most commonly used IOLs in pediatric cataract are acrylic hydrophobic because of the material’s capsule biocompatibility. However, the cost of these IOLs limit their use in a developing country.3 In rural areas, we implant hydrophilic acrylic IOLs in almost equal proportion to hydrophobic acrylic IOLs because they are more affordable for patients. Although many studies have evaluated poly(methyl methacrylate), silicone, hydrophobic, and hydrophilic acrylic IOLs in pediatric cataract patients,4–7 to our knowledge none has compared hydrophilic IOLs and hydrophobic IOLs in
Submitted: February 4, 2019 | Final revision submitted: April 2, 2019 | Accepted: May 12, 2019 From the Children’s Eye Care Center (P. Sen), Pediatric Ophthalmology and Strabismus (Kshetrapal, Shah, Mohan, Jain), and the Department of Retina and Uvea (A. Sen), Sadguru Netra Chikitsalaya, Chitrakoot, Madhya Pradesh, India. Corresponding author: Pradhnya Sen, MB BS, MS, Sadguru Netra Chikitsalaya, Chitrakoot, Jankikund, District Satna, Madhya Pradesh-210204, India. Email: [email protected]. Q 2019 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter https://doi.org/10.1016/j.jcrs.2019.05.018
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this population. In this retrospective study, we compared the visual outcomes and complications after primary in-the-bag implantation of foldable hydrophilic acrylic IOLs and foldable hydrophobic acrylic IOLs in pediatric eyes. PATIENTS AND METHODS This retrospective review comprised the records of patients who had primary lens aspiration with in-the-bag implantation of a hydrophobic or hydrophilic foldable acrylic IOL from 2010 to 2016. The study included patients from 0 to 18 years of age with unilateral or bilateral congenital or developmental cataract and a minimum follow-up of 1 year. The study was approved by an institutional review board and performed in accordance with the tenets of the Declaration of Helsinki. Exclusion criteria were cataracts associated with other ocular abnormalities (microphthalmos, microcornea, glaucoma, uveitis, coloboma) or systemic disease, traumatic or complicated cataracts, intraoperative complications, and IOL placement outside the bag. In addition, patients with a follow-up of less than 1 year were excluded from the study. The children were divided into 2 groups based on the type of IOL to be implanted; that is, hydrophilic acrylic (hydrophilic group) or hydrophobic acrylic (hydrophobic group). Preoperatively, the child’s parents or guardians were counseled on the surgical procedure and IOL implantation and the pros and cons of the IOL material. They chose the type of IOL to be implanted based on affordability; however, implantation of the hydrophilic IOL and the hydrophobic IOL was almost equally distributed throughout the study period. Preoperative Evaluation All patients had a detailed preoperative evaluation. The vision of uncooperative children was assessed using the central, steady, and maintained fixation method. Visual acuity was evaluated with age-appropriate visual acuity testing charts (eg, Lea grating paddles, Teller acuity) in preverbal children and with a Snellen chart in older children. Intraocular pressure was measured using noncontact tonometry or applanation tonometry depending on cooperation of the child. An anterior segment examination was performed at the slitlamp or under the operating microscope.
The posterior segment was examined using indirect ophthalmoscopy or B-scan ultrasonography if the media was opaque. Biometric measurements were performed using conventional keratometry in cooperative children or a handheld autokeratometer under general anesthesia in smaller children. The axial length was measured with an immersion technique using A-scan ultrasonography or a contact technique under anesthesia. Intraocular lens power was calculated using the SRK II formula8 in all cases. Although the SRK II is an older formula, it continues to be used at the institution because it has given consistently good results. In addition, some authors have used this formula in pediatric cataract surgery.4,5 The power was adjusted in children younger than 8 years using Dahan and Drusedau’s formula9 according to the patient’s age. Surgical Technique All surgeries were performed by experienced pediatric ophthalmologists (P.S., C.S., A.M., E.J.) using local anesthesia or general anesthesia, with the choice of anesthesia based on the age of the patient. The surgeons did not have a preference for which surgical technique to use or which IOL (hydrophilic or hydrophobic) to implant. The lens matter was aspirated using a phacoaspiration and/or a bimanual irrigation/aspiration cannula. A foldable acrylic hydrophilic IOL (Ocuflex ANU6, Care Group) or hydrophobic IOL (AcrySof SA60AT, Alcon Laboratories, Inc.) was implanted in the capsular bag. Primary posterior capsulorhexis with anterior vitrectomy was performed before or after IOL implantation in children younger than 8 years, those with mental disabilities, or those who had nystagmus or poor fixation. All patients received topical prednisolone 1.0% eyedrops 8 times a day in a tapering dose for 6 weeks as well as topical moxifloxacin 0.5% eyedrops 4 times a day and homatropine 2.0% eyedrops 2 times a day for 2 weeks. Postoperative Evaluation Visual acuity, refraction, corrected distance visual acuity (CDVA), and intraocular pressure measurements were assessed postoperatively at 1 day, 1 month, 6 months, and 1 year. Outcome measures included postoperative complications such as anterior chamber inflammation, pigment over the IOL, fibrinous membrane, and posterior capsule opacification (PCO). Posterior capsule opacification was defined as any central whitening or wrinkling of the
Table 1. Patient demographics by group. Parameter Sex (n) Male Female Age (y) 0–2 (n) 3–8 (n) 9–18 (n) Mean Eye (n) Right Left Nystagmus Strabismus Mean AL (mm) Mean IOL power (D) Follow-up (m) Mean Range
Hydrophilic Acrylic (51 Eyes)
Hydrophobic Acrylic (52 Eyes)
35 16
38 14
8 22 21 8.2 G 4.0
10 28 14 6.9 G 4.0
P Value .97
25 26 3 1 22.05 22.6 38.8 G 21.6 12, 84
24 28 2 3 21.50 23.00 39.4 G 20.8 12, 84
.1 .8
d d .9 .9 .8
Means G SD AL Z axial length; IOL Z intraocular lens
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Table 2. Comparison of PCO formation in eyes in which PPV and anterior vitrectomy were performed. Number (%) PCO Type
Hydrophilic IOL (n Z 23)
Hydrophobic IOL (n Z 29)
P Value
1 (4.3) 0 1 (4.3)
2 (6.8) 0 2 (6.8)
.69 d .69
Visually significant Visually insignificant Total incidence
IOL Z intraocular lens; PCO Z posterior capsule opacification; PPC Z primary posterior capsulorhexis
posterior lens capsule on slitlamp examination.10 Visually significant PCO was defined as a decrease of 2 or more lines from the postoperative CDVA or when retinoscopy or fundoscopy was not possible.11 Spectacles were prescribed at 1 month, and amblyopia therapy (ie, patching) was started when needed. Statistical Analysis Descriptive statistical analyses were performed on categorical measurements using SPSS for Windows software (version 16.0, SPSS, Inc.); the results are presented as the number (percentage) or as the mean G SD. The results were analyzed using GraphPad Prism for Windows software (version 7.00, GraphPad Software, Inc.).A The unpaired t test was used to compare the mean values in the 2 IOL groups. Comparative analysis of the 2 IOLs was performed using a contingency data table. The relative risk was calculated using the Koopman asymptotic score. The Fischer exact test was used to compare the rate of PCO formation between the 2 groups. A P value less than 0.05 was considered statistically significant. Kaplan-Meier probability curves were used to calculate the risk for developing PCO at a given interval after surgery. The Gehan-BreslowWilcoxon test and log-rank (Mantel-Cox) test tables were used to analyze the difference in probability curves between the 2 IOL groups.
RESULTS Eighty patients (103 eyes) met the inclusion criteria and were included in the study. Of the 80 patients, 53 were boys and 27 were girls. Lens matter aspiration with IOL implantation was performed in 51 eyes (28 hydrophilic group; 23 hydrophobic group); primary posterior capsulotomy (PPC) and anterior vitrectomy were also performed in 52 eyes (23 hydrophilic group; 29 hydrophobic group). Twenty-seven eyes (26.2%) had congenital cataract, and 76 eyes (73.8%) had developmental cataract. Table 1 shows the patients’ demographics and associated ocular morbidities. There were no significant differences in preoperative characteristics between the hydrophilic group and the hydrophobic group. The preoperative CDVA ranged from fixing and following light to 20/40 in both groups; 18 eyes (17.5%) had a CDVA of 20/200 or better. Postoperatively, 37 eyes
(72.5%) in the hydrophilic group and 39 eyes (75.0%) in the hydrophobic group had a CDVA of 20/40 or better; the difference between groups was not significant (P O .05). In both groups, 18 eyes were amblyopic and received amblyopia therapy. Postoperatively, no eye had an anterior chamber reaction of grade 2 or higher. In all cases, the reaction resolved with topical medications in 4 to 6 weeks. There were no cases of pigment over the IOL, IOL decentration, wound leak, or endophthalmitis. The most common complication was PCO, occurring in 30 of 103 eyes as of the last follow-up. Tables 2 and 3 and Figure 1 show the number of eyes with PCO in each IOL group by surgical technique. The rate was higher in eyes that did not have PPC and anterior vitrectomy. In eyes having PPC and anterior vitrectomy, there was no significant difference in the rate of PCO between the 2 IOL groups (P Z .69). Figure 2 shows 5-year postoperative slitlamp images of a clear visual axis (ie, no PCO) in eyes with a PPC and anterior vitrectomy. In eyes in which PPC and anterior vitrectomy were not performed, the hydrophilic group was at risk for developing visually significant PCO earlier than the hydrophobic group. However, long-term analysis of the total PCO rate found no statistically significant difference between the 2 groups (P Z .5). Of the 17 eyes with visually significant PCO, 15 (11 hydrophilic group; 4 hydrophobic group) had a Nd:YAG capsulotomy. Membranectomy was performed in 1 eye in each group. The mean follow-up duration after Nd:YAG capsulotomy and membranectomy was 3.2 years. No complications (eg, IOL pitting, retinal detachment, cystoid macular edema) were seen in any eye having these procedures. Figures 3 and 4 show the Kaplan-Meier survival plots for eyes that developed PCO (visually significant and insignificant); the length of the blue curves and red curves were
Table 3. Comparison of PCO formation in eyes in which PPV and anterior vitrectomy were not performed. Number (%) PCO Type
Hydrophilic IOL (n Z 28)
Hydrophobic IOL (n Z 23)
P Value
11 (39.3) 5 (17.8) 16 (57.1)
3 (13.4) 8 (34.7) 11 (47.8)
.03* .16 .5
Visually significant Visually insignificant Total incidence
IOL Z intraocular lens; PCO Z posterior capsule opacification; PPC Z primary posterior capsulorhexis *Relative risk of 4.5 for significant PCO formation in hydrophilic group
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Figure 1. Number of eyes with PCO by intraocular lens group and surgical technique (PCO Z posterior capsule opacification; PPC Z primary posterior capsulotomy).
not identical because of variable follow-up times. The 3year cumulative incidence of no PCO formation was 80.8% (42 eyes) in the hydrophobic group and 70.6% (36 eyes) in the hydrophilic group. The survival rate (ie, no PCO formation at 5-year follow-up) when PPC and anterior vitrectomy were performed was 93.1% (27 eyes) in the hydrophobic group and 95.6% (22 eyes) in the hydrophilic group; the difference was not statistically significant (P Z .4; Mantel-Cox test). DISCUSSION Posterior capsule opacification is the most common complication of pediatric cataract surgery and occurs in almost all cases if the posterior capsule is left intact.12 The rate of PCO decreases with advancing age.13–15 If PCO obscures the visual axis, it is as amblyogenic as the cataract itself.14 However, advances in IOL material, IOL edge design, and surgical technique have helped minimize the rate of PCO formation.16 The rate of PCO is markedly reduced when PPC and anterior vitrectomy are performed.15 In most cataract surgery techniques, small incisions are created; thus, foldable acrylic (hydrophobic or hydrophilic) IOLs have become the preferred choice. Hydrophobic IOLs reduce the rate of PCO because they adhere to the collagen membrane, leading to tight apposition of IOLs to the posterior capsule. This results in less space between the IOL and the posterior capsule through which lens epithelial cells can migrate.17,18 However, these IOLs are expensive; therefore,
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acrylic hydrophilic IOLs are often used rather than hydrophobic IOLs in developing countries. Hydrophilic IOLs have excellent uveal biocompatibility but lower capsule biocompatibility.19 The choice of IOL in our study was dependent on how much the parents or guardians could afford. To our knowledge, no previous study has compared hydrophilic IOLs and hydrophobic IOLs in the pediatric cataract population. In a study of 120 patients by Kugelberg et al.,20 18.6% of eyes with hydrophilic IOLs and 4.0% of eyes with hydrophobic IOLs developed PCO. However, their patients were adults and thus had a lower PCO rate than our pediatric cohort (17 [33.3%] of 51 eyes and 13 [25.0%] of 52 eyes, respectively). In addition, the PCO rate was followed for 1 year only in the Kugelberg et al. study. In a study of hydrophilic IOL implantation in pediatric eyes with cataract by Adhikari and Shrestha,3 7% of eyes developed PCO over a mean follow-up of 13.7 months. This is significantly less than the incidence in our study (33.3 %), which might be the result of the much longer follow-up (38.8 months) of our patients. In our study, the PCO rate in eyes in the hydrophobic group that had PPC and anterior vitrectomy (6.8%) is comparable to that in other studies. In a study by Ram et al.,21 13.3% of eyes in which hydrophobic IOLs were implanted using a similar surgical approach developed PCO. The rate of PCO was 10.8% in a study by Vasavada et al.7 Aasuri et al.4 found visually significant opacification in 21.05% of eyes with hydrophobic IOLs when the posterior capsule was left intact. In the present study, the rate of PCO was 13.4% in eyes in which the posterior capsule was left intact. The lower incidence in our study might have been the result of our strict criteria, which excluded complicated cataract cases and surgeries. When PPC and anterior vitrectomy were performed, the PCO rate was 4.3% in the hydrophilic group and 6.8% in the hydrophobic group. The difference was not significant, showing that when PPC and anterior vitrectomy are performed and the IOL is implanted in the bag, the IOL material does not affect the outcomes. The incidence of visually significant PCO was statistically significantly higher in the hydrophilic group when PPC and anterior vitrectomy were not performed (P Z .03). However, the overall PCO rate was comparable in the 2 IOL
Figure 2. Five-year postoperative slitlamp images of clear visual axis (ie, no posterior capsule opacification) in an eye with a hydrophilic IOL (a) and an eye with a hydrophobic IOL (b). Both eyes had primary posterior capsulotomy and anterior vitrectomy (IOL Z intraocular lens).
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Figure 3. Kaplan-Meier survival plots for eyes in which primary posterior capsulotomy and anterior vitrectomy were not performed (IOL Z intraocular lens).
groups, as shown by the Kaplan-Meier survival curves (Figure 3). Eyes with significant PCO had an Nd:YAG capsulotomy (15 eyes) or membranectomy (2 eyes). Neodymium:YAG capsulotomy is easier to perform in older children because in general they are cooperative during outpatient procedures. No complications, such as IOL pitting, occurred in any eye having a capsulotomy; the damage threshold for acrylic IOLs during Nd:YAG laser capsulotomy is comparable to that for silicone or poly(methyl methacrylate) IOLs.22 Other complications, such as a spike in intraocular pressure, retinal detachment, or cystoid macular edema, were not reported as of the last follow-up examination. Postoperatively, 72.5% in the hydrophilic group and 75.0% in the hydrophobic group had a CDVA of 20/40 or better. In studies by Adhikari and Shrestha3 and Aasuri et al.,4 the visual acuity was 20/40 or better in 44.5% of eyes and 60.8% of eyes, respectively. Our results were better because our study included a higher proportion of eyes with developmental cataract, for which the prognosis is likely better. In our study, the postoperative visual outcomes were comparable between hydrophilic IOLs and hydrophobic IOLs. The rate of significant PCO formation was higher in the hydrophilic group when the posterior capsule was left intact. When PPC and anterior vitrectomy were performed, the results were comparable between the 2 IOL types. The PCO was successfully treated with Nd:YAG capsulotomy with no long-term adverse events, such as reopacification. A strength of our study is that we included only eyes with developmental or congenital cataract in which the IOL was implanted in the bag. This allowed us to make a valid comparison of the 2 IOL materials. A major limitation of our study is its retrospective nature. Also, the choice of the IOL to be implanted depended on how much the parent or guardian could afford to pay. To avoid potential bias, prospective studies with random allocation to the 2 groups should be performed. In conclusion, when PPC and anterior vitrectomy were performed, the PCO rates were low and the material of Volume 45 Issue 10 October 2019
Figure 4. Kaplan-Meier survival plots for eyes in which PPC and anterior vitrectomy were performed (IOL Z intraocular lens; PPC Z primary posterior capsulotomy).
the IOL did not affect the outcomes. In cases in which the posterior capsule was left intact, eyes with hydrophilic IOLs had a higher incidence of visually significant PCO. However, the PCO was treated with Nd:YAG capsulotomy without complications. Thus, hydrophilic IOLs can be a good alternative to hydrophobic IOLs when the patient’s ability to afford more expensive IOLs is a major concern.
WHAT WAS KNOWN Hydrophobic acrylic intraocular lenses (IOLs) are the preferred IOL in pediatric cataracts. Foldable hydrophilic IOLs are safe to use in children.
WHAT THIS PAPER ADDS The surgical technique (primary posterior capsulotomy and anterior vitrectomy) was more important than the IOL material in posterior capsule opacification (PCO) formation. Nd:YAG laser capsulotomy was successful in treating PCO in older children without long-term complications.
REFERENCES 1. Gilbert C, Foster A. Childhood blindness in the context of vision 2020 d the right to sight. Bull World Health Organ 2001; 79:227–232 2. Foster A, Gilbert C, Rahi J. Epidemiology of cataract in childhood: a global perspective. J Cataract Refract Surg 1997; 23:601–604 3. Adhikari S, Shrestha UD. Pediatric cataract surgery with hydrophilic acrylic intraocular lens implantation in Nepalese children. Clin Ophthalmol 2018; 12:7–11 4. Aasuri MK, Fernandes M, Pathan PP. Comparison of acrylic and polymethyl methacrylate lenses in a pediatric population. Indian J Ophthalmol 2006; 54:105–109 5. Bhusal S, Ram J, Sukhija J, Pandav SS, Kaushik S. Comparison of the outcome of implantation of hydrophobic acrylic versus silicone intraocular lenses in pediatric cataract: prospective randomized study. Can J Ophthalmol 2010; 45:531–536 6. Ram J, Kaushik S, Brar GS, Gupta A. Neodymium:YAG capsulotomy rates following phacoemulsification with implantation of PMMA, silicone, and acrylic intraocular lenses. Ophthalmic Surg Lasers 2001; 32:375–382 7. Vasavada AR, Trivedi RH, Nath VC. Visual axis opacification after Arcysof intraocular lens implantation in children. J Cataract Refract Surg 2004; 30:1073–1081; erratum, 1826 8. Sanders DR, Retzlaff J, Kraff MC. Comparison of the SRK IIÔ formula and other second-generation formulas. J Cataract Refract Surg 1988; 14:136–141 9. Dahan E, Drusedau MUH. Choice of lens and dioptric power in pediatric pseudophakia. J Cataract Refract Surg 1997; 23:618–623
PCO FORMATION IN HYDROPHILIC VS HYDROPHOBIC IOLS IN PEDIATRIC CATARACT
10. Rajavi Z, Mokhtari S, Sabbaghi H, Yaseri M. Long-term visual outcome of congenital cataract at a tertiary referral center from 2004 to 2014. J Curr Ophthalmol 2015; 27:103–109 11. Pande MV, Ursell PG, Spalton DJ, Heath G, Kundaiker S. High-resolution digital retroillumination imaging of the posterior lens capsule after cataract surgery. J Cataract Refract Surg 1997; 23:1521–1527 12. Lim ME, Buckley EG, Prakalapakorn SG. Update on congenital cataract surgery management. Curr Opin Ophthalmol 2017; 28:87–92 13. Trivedi RH, Wilson ME, Vasavada AR, Shah SK, Vasavada V, Vasavada VA. Visual axis opacification after cataract surgery and hydrophobic acrylic intraocular lens implantation in the first year of life. J Cataract Refract Surg 2011; 37:83–87 14. Hayashi H, Hayashi K, Nakao F, Hayashi F. Quantitative comparison of posterior capsule opacification after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation. Arch Ophthalmol 1998; 116:1579–1582 15. Vasavada A, Desai J. Primary posterior capsulorhexis with and without anterior vitrectomy in congenital cataracts. J Cataract Refract Surg 1997; 23:645–665 16. Ram J, Brar GS, Kaushik S, Gupta A, Gupta A. Role of posterior capsulotomy with vitrectomy and intraocular lens design and material in reducing posterior capsule opacification after pediatric cataract surgery. J Cataract Refract Surg 2003; 29:1579–1584 17. Buehl W, Findl O. Effect of intraocular lens design on posterior capsule opacification. J Cataract Refract Surg 2008; 34:1976–1985 18. Buehl W, Findl O, Menapace R, Sacu S, Kriechbaum K, Koeppl C, Wirtitsch M. Long-term effect of optic edge design in an acrylic intraocular lens on posterior capsule opacification. J Cataract Refract Surg 2005; 31:954–961 19. Kleinmann G, Zaugg B, Apple DJ, Bleik J. Pediatric cataract surgery with hydrophilic acrylic intraocular lens. J AAPOS 2013; 17:367–370
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€m C. Posterior capsule 20. Kugelberg M, Wejde G, Jayaram H, Zetterstro opacification after implantation of a hydrophilic or a hydrophobic acrylic intraocular lens; one-year follow-up. J Cataract Refract Surg 2006; 32:1627–1631 21. Ram J, Brar GS, Kaushik S, Sukhija J, Bandyopadhyay S, Gupta A. Primary intraocular lens implantation in the first two years of life: safety profile and visual results. Indian J Ophthalmol 2007; 55:185–189 22. Trinavarat A, Atchaneeyasakul L, Udompunturak S. Neodymium:YAG laser damage threshold of foldable intraocular lenses. J Cataract Refract Surg 2001; 27:775–780
OTHER CITED MATERIAL A. GraphPad Software. Introducing Prism8. Available at: https://www .graphpad.com/scientific-software/prism. Accessed June 27, 2019
Disclosures: None of the authors has a financial or proprietary interest in any material or method mentioned.
First author: Pradhnya Sen, MB BS, MS Children’s Eye Care Center, Sadguru Netra Chikitsalaya, Chitrakoot, India
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