Dr. Jaspreet Sukhija, Dr. Savleen kaur
The most important consideration in modern pediatric cataract surgery is keeping the visual axis clear. Even in the hands of the most experienced surgeons, with the best available intraocular lenses (IOL) and instrumentation, posterior capsular opacification is inevitable in some children.1-3 The search for a better surgical technique and improvisations in intraocular lens designs is ongoing.
Anterior vitrectomy in a child poses the problems of cystoid macular edema, increased risk of retinal detachment, vitreous strands entering the incision and risk of enlargement of posterior capsulotomy.4 Moreover removing a part of the vitreous in a growing can have later consequences which are yet unexplored. The purpose of our study was to compare posterior optic capture of IOL without anterior vitrectomy and endocapsular IOL implantation with anterior vitrectomy in the two eyes of the same patient.
It was a prospective interventional study. Consecutive children with bilateral cataract aged less than 5 years undergoing cataract surgery were studied prospectively for a period of 1 year. Informed consent was taken from the parent /guardian of the child. The study conferred to the declaration of the tenets of Helsinki. Eyes with traumatic cataract, microphthalmia, microcornea and secondary IOLs along with other ocular abnormalities were excluded.
Data collected included the age at surgery, laterality, sex of the child, significant systemic history, type of cataract, axial length preoperatively, type and power of intraocular lens, intraoperative and postoperative complications with any visual axis opacification or need for resurgery and postoperative retinoscopy/refraction. IOL power was calculated based on axial length values by A scan and keratometry performed by hand held keratometer wherever possible. The target postoperative refraction was based on the patient’s age and fellow-eye status. Adjustment was made for the IOL power when an optic capture was planned. IOL power was implanted with predicted error +4D in <6months, +3D in 6months-1year, +2 D 1year-2year, +1D 2 to 3 year and emmetropia after that. Objective streak retinoscopy was first done after surgery at an interval of two weeks when no inflammation was documented and then repeated at six weeks by a single optometrist. Spectacles were prescribed based on the retinoscopy value with additional +3 D upto 2.5 years beyond which bifocals were prescribed. Intraocular pressure was measured with Perkins handheld applanation tonometer preoperatively as well postoperatively. B scan ultrasonography was performed in eyes where a dense cataract precluded the view of the fundus.
Surgical technique- In one eye we performed anterior vitrectomy and placed the IOL in the bag whereas in the other eye of the same patient no anterior vitrectomy was performed and the IOL optic was prolapsed behind the posterior capsule with the haptics in the bag. For descriptive purposes we labelled the eyes undergoing posterior optic capture of the IOL as Group 1 and eyes with endocapsular IOL implantation as group 2.
At follow up visits’ patients were examined under anaesthesia and slit lamp evaluation was done when possible. The posterior optic capture was confirmed by observing the ‘spindle’ of the posterior capsule on subsequent examinations under anesthesia. Eyes with no/partial capture along with the fellow eyes were excluded. Visual axis opacification was defined as significant if there was lens epithelial cell regrowth extending into the pupillary space and interfering with vision/inability to perform undilated retinoscopy in that eye. A record of all post-operative findings as well as complications till a follow up of one year was noted and compared.
STATISTICAL ANALYSIS: Statistical analyses were performed using SPSS program. P value of < 0.05 was considered statistically significant. Descriptive analysis was done on all patients and a record of both the eyes was kept. The baseline parameters and rates of complications were studied in both groups. Chi square test was used to compare these rates in the two age groups for categorical data and t-test for continuous data.
Over the study period, we had recruited 16 patients who were subsequently planned for posterior optic capture in one eye and bag implantation of the IOL in the other eye. IOL could be successfully captured in fifteen children. In two children IOL was found in sulcus on the subsequent post-operative visit in the eye where posterior optic capture was attempted. Another was excluded because the eye in which bag implantation was planned; the IOL had to be placed in sulcus because of extended anterior capsulorhexis. Hence a total of thirteen children were included for final visual outcome analysis. However we did include them when observing for complications.
The mean age at the time of surgery was 21 ± 14.7 months (median 12 months; range (5 months to 4 years). The mean follow-up was 12.69 ± 1.06 months (median 12 months; range 12 to 15 months). The preoperative parameters of all the patients are listed in Table 1. The two eyes were matched in terms of biometry (Table 2). The axial length was measured by the A scan in all patients and the keratometry by handheld keratometer.
The intraoperative difficulties are listed in table 3; which were not significantly different between the two groups.
Table 4 further adverse events occurring postoperatively in all patients. No cases of clinically significant macular edema, retinal detachment or endophthalmitis were observed. None of the patients required surgery for control of IOP. The posterior optic capture was confirmed by observing the ‘spindle’ of the posterior capsule on subsequent examinations under anesthesia. All eyes in both groups maintained a clinically centred IOL with clear visual axis. One patient developed anterior capsular phimosis in the right eye (posterior optic capture). The rate of fibrinous complications (IOL deposits and synechiae) were more in the eyes with IOL in the bag (6/ 13) vs eyes where posterior optic capture was done (1/13); p=0.039.
Mean postoperative IOP at one year was 13.05 ± 2.18 mm Hg in group 1 and 13.4 mm ± 2.76 Hg in the group 2 (p=0.82). The refractive error could not be determined preoperatively for any of the cataractous eyes. The mean spherical equivalent at 6 weeks after surgery was 0.46 ± 1.14 D in group 1 and was not significantly different from group 2. (0.48 ± 0.96) (p=0.89.)
We compared the benefits and demerits of posterior optic capture vs in the bag IOL implantation in two eyes of the same patient in this study. We did not find any significant difference in terms of visual axis clarity between eyes having a vitrectomy and those not having one. Posterior optic capture resulted in a well centred IOL and prevents visual axis opacification comparable to endo-capsular implantation of IOL. In addition, it decreases the inflammatory response in the eye. To the best of our knowledge, this is the first ‘prospective study’ of its kind. The biggest merit of our study was that we performed the two procedures in either eye of the same patient. The same surgeon implanted similar IOL in both eyes. The two groups are obviously matched in terms of age, biometry and this also eliminates a lot of patient factors which are responsible for bias in other studies.
Anterior vitrectomy brings its own set of complications in growing eye of a child.5 We do not yet know, what are the effects of vitreous removal in cases of pediatric cataract. Vitrectomy can increase the chances of cystoid macular edema which is often underreported in children due to lack of imaging.6 How much vitrectomy is “adequate” in children is not quantifiable and hence may be subjective. Strands of vitreous in the anterior chamber may predispose to more fibrinous complications. Enlargement of PPC may also occur at the time of vitrectomy making it impossible to implant IOL in the bag.7 Despite these disadvantages, we are routinely performing anterior vitrectomy due to its biggest advantage in preventing posterior capsular opacification in congenital cataract surgery. But even after primary posterior capsulectomy with vitrectomy, many children’s visual axes become reoccluded by secondary membranes necessitating repeated membranectomy and at the same time breaks the anterior vitreous barrier.
In the hands of a well-trained surgeon, posterior optic capture needs minimal manipulation and does away with vitrectomy related complications. It was first advocated by Gimbel and colleagues and later propagated by others.8-11 The major benefit achieved with posterior optic capture is optimum centration of IOL and prevention of vitreous herniation. It results in fusion of the capsular bag’s anterior and posterior leaflets for almost 360 degrees. Since most of the circumference of the posterior capsule opening is anterior to the lens optic, Elschnig pearls do not get deposited on the vitreous face reducing lens epithelial cell migration and visual axis obscuration.12 Moreover, it can be carried out even if the anterior capsulorhexis is eccentric.13
Raina et al did a prospective study concluding optic capture without vitrectomy as a promising technique to prevent opacification but the authors did not compare it with the ‘gold standard’ bag implantation of IOL with vitrectomy.14 The studies which necessitate the use of anterior vitrectomy with capture either use a PMMA IOL with haptics in sulcus 4,12 or have reported results in different set of patients retrospectively with a short follow up.13,15 The latest studies use acrylic IOLs but those for optic capture are three-piece design.16
It has been hypothesized that there might be a low incidence of glaucoma after IOL optic capture due to the backward movement of the optic part of IOL.17 off course a study with longer follow up is needed in this regard. A part of the success of the procedure can also be attributed to the IOL design and the make of the optic-haptic junction.17,18 The Hoya IOL has an optic with diameter of 6 mm with angulated haptics and the overall length of the IOL is 12.5 mm, which is less than other acrylic single-piece IOLs. The design of the Hoya IOL could be an additional factor in low incidence of complications.18 Posterior optic capture is a technically challenging procedure. Care should be taken in cases where we plan posterior optic capture, the PPC should be made 1-1.5 mm smaller than the IOL optic. It can be larger than routine but not large enough to cause spontaneous release of the optic. Trypan blue staining of the posterior capsule may be done by beginners to achieve an optimum capture.19 For surgeons who opt for making a PPC after IOL implantation, posterior optic capture can be a viable option.
A meta-analysis of all published literature on posterior optic capture without vitrectomy in children describes the technique to be a helpful surgical method in preventing PCO and geometric decentration with robust efficacy and safety. 20 It is safe to conclude that posterior optic capture is a promising technique of IOL implantation and can be effectively used even in young children in the absence of an additional procedure that is vitrectomy. In conclusion, posterior optic capture is a reasonable alternative to endocapsular implantation of IOL with significantly fewer inflammatory sequelae and at the same time preserving the vitreous in a growing eye.
- Plager DA, Lynn MJ, Buckley EG, Wilson ME, Lambert SR; Infant Aphakia Treatment Study Group. Complications in the first 5 years following cataract surgery in infants with and without intraocular lens implantation in the Infant Aphakia Treatment Study. Am J Ophthalmol. 2014 Nov;158(5):892-8
- Yangzes S, Kaur S, Gupta PC, Sharma M, Jinagal J, Singh J, Ram J. Intraocular lens implantation in children with unilateral congenital cataract in the first 4 years of life. Eur J Ophthalmol. 2018 Jul 30:1120672118790193.
- Sukhija J, Kaur S, Ram J, Yangzes S, Madan S, Jinagal J. Outcome of various hydrophobic acrylic intraocular lens implantations in children with congenital cataract. Eur J Ophthalmol. 2017 Apr 13:0.
- Vasavada AR, Trivedi RH, Singh R. Necessity of vitrectomy when optic capture is performed in children older than 5 years. J Cataract Refract Surg 2001;27:1185–1193
- Gimbel HV, Ferensowicz M, Raanan M, DeLuca M. Implantation in children. J Pediatr Ophthalmol Strabismus 1993; 30:69–79.
- Hoyt CS, Nickel B. Aphakic cystoid macular edema; occurrence in infants and children after transpupillary lensectomy and anterior vitrectomy. Arch Ophthalmol 1982; 100:746–749.
- Gimbel HV, DeBroff BM. Management of lens implant and posterior capsule with respect to presentation of secondary cataract. Operative Tech Cataract Refract Surg 1998; 1:185–190.
- Gimbel HV, DeBroff BM: Posterior capsulorhexis with optic capture: maintaining a clear visual axis after pediatric cataract surgery. J Cataract Refract Surg 1994, 20:658-64.
- Gimbel HV. Posterior continuous curvilinear capsulorhexis and optic capture of the intraocular lens to prevent secondary opacification in pediatric cataract surgery. J Cataract Refract Surg. 1997;23 Suppl 1:652-6
- Gimbel HV. Posterior capsulorhexis with optic capture in pediatric cataract and intraocular lens surgery. Ophthalmology. 1996 Nov;103(11):1871-5.
- Argento C, Badoza D, Ugrin C: Optic capture of the AcrySof intraocular lens in pediatric cataract surgery. J Cataract Refract Surg 2001, 27:1638-42.
- Vasavada AR, Trivedi RH. Role of optic capture in congenital cataract and intraocular lens surgery in children. J Cataract Refract Surg 2000; 26:824–831.
- Koch DD, Kohnen T. Retrospective comparison of techniques to prevent secondary cataract formation after posterior chamber intraocular lens implantation in infants and children. J Cataract Refract Surg 1997; 23:657–663.
- Raina UK, Gupta V, Arora R, Mehta DK. Posterior continuous curvilinear capsulorhexis with and without optic capture of the posterior chamber intraocular lens in the absence of vitrectomy. J Pediatr Ophthalmol Strabismus. 2002 Sep-Oct;39(5):278-87.
- Cicik ME, Doğan C, Bölükbaşı S, Cinhüseyinoğlu MN, Arslan OŞ. Comparison of Two Intraocular Lens Implantation Techniques in Pediatric Cataract Surgery in Terms of Postoperative Complications. Balkan Med J. 2018 Mar 15;35(2):186-190.
- Vasavada AR, Vasavada V, Shah SK, Trivedi RH, Vasavada VA, Vasavada SA, Srivastava S, Sudhalkar A. Postoperative outcomes of intraocular lens implantation in the bag versus posterior optic capture in pediatric cataract surgery. J Cataract Refract Surg. 2017 Sep;43(9):1177-1183.
- Xie Y-B, Ren M-Y, Wang Q, Wang L-H. Intraocular lens optic capture in pediatric cataract surgery. International Journal of Ophthalmology. 2018;11(8):1403-1410. doi:10.18240/ijo.2018.08.24.
- Sukhija J, Kaur S, Ram J. Outcome of a New Acrylic Intraocular Lens Implantation in Pediatric Cataract. J Pediatr Ophthalmol Strabismus. 2015 Nov-Dec;52(6):371-6.
- Sharma N, Balasubramanya R, Dada VK, Vajpayee RB. Efficacy of trypan blue in posterior capsulorhexis with optic capture in pediatric cataracts [ISRCTN48221688]. BMC Ophthalmol. 2006 Mar 16;6:12.
- Zhou HW, Zhou F. A Meta-analysis on the clinical efficacy and safety of optic capture in pediatric cataract surgery. Int J Ophthalmol. 2016 Apr 18;9(4):590-6.
Table 1: Baseline characteristics of the patients
|children less ≤ 1 year||6|
|Patients with systemic associations/infections*||2|
|patients with strabismus||2|
|Eyes with PHPV^||0|
|Eyes with total white cataract||9|
|Eyes with zonular cataract||17|
*Both patients had positive history of TORCH group of infections
^PHPV=Persistent Hyperplastic Primary Vitreous
Table 2: Biometric profile for both groups
|GROUP 1||GROUP 2||P value|
|Mean axial length(mm)||20.74 ± 15.4||20.69 ± 11.7||0.911|
|Mean keratometry(D)||43.5 ± 1.74||44.1 ± 2.48||0.49|
|Mean IOL power implanted||27.35 ± 3.4||27.58 ± 3.2||0.86|
Table 3: Details of intraoperative findings/complications
|INTRAOPERATIVE COMPLICATIONs||GROUP 1||GROUP 2||P value|
|Anterior capsular fibrosis||2||0||0.63|
|Size of anterior capsulorhexis (mean in mm)||5.323 ± 1.2||5.41 ± 1.1||0.8|
|Escaped anterior capsulorhexis*||1||0||0.95|
|Size of posterior capsulorhexis (mean in mm)||3.83 ± 2.2||3.91 ± 2.1||0.89|
|Large posterior capsulorhexis^||1||1||1.0|
|Pre-existing posterior capsular defect||1||0||0.956|
*Despite the large capsulorhexis, the IOL could still be captured successfully
^Larger than usual but still well centered and optimal.
TABLE 4: A Record of the postoperative adverse events in both groups
|Adverse events||GROUP 1||GROUP 2||P VALUE|
|Visual axis opacification||0||0||–|
|Anterior capsular phimosis||1||0||0.49|
|Inflammatory sequalae 1. Lenticular adhesions and Pigments on IOL
2. Anterior synechiae/side port synechiae
*IOL edge was partly visible in the pupillary axis post operatively but did not need re-surgery