Orissa Journal of Ophthalmology 2008 POSTERIOR AND ANTERIOR FOR THE MANAGEMENT OF PAEDIATRIC .

Dr Partha Biswas B B Foundation, Kolkata

INTRODUCTION chamber with high viscosity substance like Sodium Hyaluronate. Performing a surgery in a very young child, leaving an intact posterior lens capsule behind, invariably  Initiation of the PPC and flap : 26-G Cystitome needle results in rapid (within 2years post-op) Visual Axis descends onto the capsule at a slant, engages the Opacification (VAO)and its amblyogenic effects. central capsule, lifts it up towards the surgeon, and Moreover, the Anterior Vitreous Face (AVF), in close link at the same time initiates the puncture. A small flap to the posterior capsule being more “reactive” in infants is created by pushing the margin of the puncture & young children, acts as a scaffold for the proliferation inferiorly. of epithelial cells of the lens and also for metaplastic  High viscosity Sodium Hyaluronate is slowly injected pigment epithelial cells, exudates & cells derived from the through the puncture between the capsule and the breakdown of the blood-aqueous barrier. The severe vitreous face. (Forceful injection through the tear can inflammatory response in smaller age-group children may extend it towards the periphery). lead to a fibrous membrane formation over an intact AVF,  Additional viscoelastic is placed over the posterior resulting in VAO. Therefore, removal of the central part capsule surrounding the puncture.This flattens the of posterior capsule & the anterior vitreous is considered central posterior capsuleand reduces potential a routine step of the of younger children peripheral extension. of today.  The flap is then held with forceps and POSTERIOR CAPSULOTOMY posterior capsulorhexis accomplished. Applied anatomy & physiology of the posterior lens  In case of a pre-existing PC defect, an attempt should capsule : be made to convert it into a primary PCC with an Utrata forceps under high-viscosity Sodium  The posterior lens capsule is 3-5 times thinner than Hyaluronate. the anterior lens capsule, being about 4-9 micrometre in thickness, the central part being the thinnest.  Some surgeons use dye (trypan blue) for better visualization of the capsule.  The mechanical strength of the posterior lens capsule (ultimate strain, load ,elastic stiffness, stress and Architecture of the PC opening : elastic modulus)have been found to decrease Size, Centricity and Shape :-

markedly with age. ( Extensibility: by a factor of 2  An optimum sized (1-1.5 mm smaller than the IOL during the lifespan, and forces required to break the optic), centric, circular PC opening should be ideally posterior capsule by a factor of 5.) desired by all.

The Surgical Steps :  Optimization of the size of the PC opening is of utmost  Aspiration of lens matter with 2-port automated importance.It has to eliminate or delay the formation irrigation-aspiration system, of VAO, and yet leave sufficient capsular support to

 Inflation of the capsular bag and filling of the anterior achive PC IOL implantation, either primary or

64 Orissa Journal of Ophthalmology 2008 secondary (“in-the-bag” or in the ciliary sulcus). Very Timing of capsulotomy :primary/secondary :

small central openings tend to spontaneously close  With the advent of higher quality vitrectomy machines & chances of synechiae increase. & sharp, high-speed cutting hand-pieces, primary  The size of the PCCC is also extremely important vitrectomy has become a very safe procedure with when attempting to capture the optic of the IOL.(Too low post-op rates of occurrences of Retinal small makes it difficult to capture and too large makes Detachment & CME. it difficult for the optic to remain captured).  It is recommended at present to ‘treat’ the PC as a Methods of creating the PC opening : primary procedure in young children. Capsulorhexis/Capsulotomy? Timing of capsulotomy: before/after IOL implantation:  The manual technique of Primary posterior  Though visibility is poor capsulotomy after IOL capsulorhexis makes it possible to achieve an opening implantation can achieve an easier and more stable with a strong margin that facilitates safe anterior IOL fixation & a wider PC opening. vitrectomy, prevents uncontrolled widening of the PC opening, provides good support of IOL over the PC  In cases of capsulotomy being done prior to IOL & even allows optic capture if desired. implantation, extension may hamper achieving

 Some surgeons prefer the use of a vitrector to cut an successful “in-the-bag” fixation. Also IOL opening in the PC, instead of a PCCC, when implantation is difficult if the eye is soft or non- vitrectomy is planned along with a posterior vitrectomised. However, there is better visibility. capsulotomy. The use of Radiofrequency diathermy  The common practice is to perform IOL implantation for this purpose has been reported in the literature. after limbal vitrectomy in children >4yrs of age and Surgical vs YAG Laser capsulotomy : IOL implantation before vitrectomy

 Routinely used by most surgeons for a primary otherwise. However, in the presence of a large PC procedure, the re-opacification rate remains much plaque, it is preferable to implant an IOL before lower in cases of surgical capsulotomy as it is possible posterior capsulotomy in children of any age.

in these cases to ‘treat’ the anterior vitreous face  It is to be remembered in this context that, the also. radiofrequency bipolar unit is not easily manipulated  Though Nd-YAG Laser capsulotomy can be beneath an IOL & is therefore usually performed on performed both as secondary and also as primary the PC, from an anterior approach, prior to IOL procedures (with lasers mounted vertically on insertion. operating microscopes), numerous studies have Leaving behind an intact PC : shown this to have a very high rate of reopacification. Also, sometimes, a transient rise of IOP has been  Generally speaking, the PC may be left intact when described by some. The cost and non-availability of the age of the child at the time of surgery is >= 8yrs the instrument in children’s hospitals or paediatric when he/she can be reasonably expected to co- ophthalmology offices may be additional barriers to operate for a secondary YAG laser capsulotomy at a the use of YAG laser. later date.

 Most surgeons of the day, prefer to perform a primary  However, a primary posterior capsulotomy is to be surgical capsulotomy that will hopefully preclude the performed at later date if YAG laser availability is in need for a secondary laser capsulotomy. question, a PC anomaly (plaque / defect) is present

 A secondary surgical capsulotomy may be needed in or when the child is developmentally delayed or unco- case secondary cataracts regrow. operative for YAG laser capsulotomy. 65 Orissa Journal of Ophthalmology 2008 ANTERIOR VITRECTOMY swiped from each port to rule out the possibility of Some important anatomical considerations : vitreous strands entering the incisions.

 The unique surgical anatomy of the infant eye require  Some have reported passing a pre-placed 8-0 Vicryl modification of standard vitreous surgery techniques. suture across the sclerotomy site to facilitate closure after vitreous removal.  A major anatomic constraint is the relative size of the pars plana which is incompletely developed in Some preferential practices : the newborn(attaining a width of >3mm at 62wks Aids / Techniques for better visualization :-

post conception), so that the anterior lies just  Kenalog injection into the A/C provides a means for behind the pars plicata. Thus entry incisions for vitreo localizing & identifying vitreous gel, allowing thorough retinal surgeries in children are made through or removal of the prolapsed vitreous & alerting surgeons anterior to the region of the pars plicata to avoid to residual vitreous strand that might go unnoticed. It iatrogenic retinal breaks. also allows surgeons to observe vitreous behavior so  Some studies have further shown that pars plana was that they can avoid maneuvers that increase vitreous 2.2 and 2.5 for nasal and temporal aspects at <6 mnths traction or prolapse. of age, 2.7 and 3 at 6–12 mnths, 3.0 & 3.1 at 1–2 yrs Role of no-suture Vitrectomy :- & 3.2 and 3.8 at 2-6 yrs of age.  Sutureless pars plana vitrectomy through self-sealing  Also, it has been reported that a linear relationship sclerotomies have been reported in literature & both exists between pars plana width and axial length of advantages & disadvantages of the technique have eye.In new borne the AL is 12mm.In cataractous been cited by many research work. the AL may be even shorter and therefore the  Some have concluded that UBM showed no pars plana may be assumed to be shorter too. difference in the amount of visible incarceration Surgical technique : between conventionally sutured versus sutureless  Considering the anatomy, the entry incisions are made sclerotomies.

<= 2mm(depending upon the AL of the eye)posterior  However, several complications reported with the to the limbus in patients <1yr of age, 2.5mm posterior sutureless technique include, wound leakage, in children 1-4yrs old and 3mm posterior in children extension, dehiscence, haemorrhage, vtireous &/or who are 4yrs of age or older. retinal incarceration, retinal tear, retinal dialysis.  The aim is to remove the central anterior vitreous Moreover difficulty in passage of instruments have without attempting to remove all of the peripheral or also been observed when tunnels are used & it has posterior vitreous. Thus, for this limited vitrectomy, 2 been argued that this technique requires conjunctival ports are used. dissection which often needs suturing.

 Separation of the irrigation from the cutting &  Some researchers evaluating the safety & efficacy aspiration reduces hydration of the vitreous. of this technique in children with thick psuodophakic

 With an ocutome system (ATIOP), the reported membranes (undergoing secondary capsulotomy & desirable machine settings are a cut rate of 350 cuts/ vitrectomy), commented upon it to be a safe & min, an aspiration flow rate of 20mL/min & a vaccum effective approach which can be considered in of 100 mmHg. Modern vitrectors have higher cutting selective cases. rates & most now recommend that the vitreous be Judging the end-point of vitrectomy :-

cut at a rate of at least 500 cuts/min.  This question has not been answered with  At the end of the procedure, an iris spatula may be considerable precision.

66 Orissa Journal of Ophthalmology 2008

 Most surgeons advise a “generous” anterior particularly difficult to implant the IOL in a soft vitrectomy without placing the vitrector so deep that vitrectomised eye (unless, the ciliary sulcus is the visualization needs a posterior vitrectomy viewing intended location for the IOL). attachment to the operating microscope.

 In general any vitreous that tracks forward past the CONCLUSION : plane of the posterior capsuloomy needs to be To summarize, it can be said that primary surgical posterior removed and sufficient vitreous is to be removed capsulotomy & anterior vitrectomy is not only a vital & centrally so that the vitreous face cannot be used as integral step in today’s management of paediatric cataract, a scaffold by the lens epithelial cells to create a VAO. but also, fact cannot be overstressed that the treatment of Does one need to perform an anterior vitrectomy the posterior capsule & the anterior vitreous face whenever a posterior capsulotomy is being performed ? determines the ultimate outcome of paediatric cataract

 In general, this is an essential step for children upto 5 surgery. yrs of age as vitreous face opacification is likely to REFERENCES : occur if anterior vitrectomy is not performed. 1. Alexandrakis G, Peterseim MM, Wilson ME. Clinical  In children between 5-8yrs of age, it is an optional outcomes of pars plana capsulotomy with anterior stepsince chances are better that a posterior vitrectomy in pediatric cataract surgery. JAAPOS capsulotomy alone will result in a long-term clear 2002;6:163-167. visual axis. Nonetheless, if in such cases if vitreous face opacification occurs, a secondary pars plana 2. BenEzra D, Cohen E. posterior capsulotomy in anterior vitrectomy is performed. pediatric cataract surgery: the necessity of a choice. Ophthalmology 1997;104:2168-2174. Limbal vs pars plana approach for posterior capsulotomy & vitrectomy :- 3. Vasavada A, Desai J. primary posterior capsulorhexis

 In the limbal approach, it is difficult to achieve with and without anterior vitrectomy in congenital adequate size of a PC opening (as IOL has not been cataracts.J Cataract Refract Surg 1997; 23(Suppl) implanted yet) & it is also more difficult to implant 1:645-651. the IOL (especially in soft, vitrectomised eyes). Also, 4. Stager DR Jr, Weakley DR Jr, Hunter JS. Long term retinal traction may be increased if a residual vitreous rates of PCO following small incision foldable acrylic strand remains attached to the anterior wound. intraocularlens implantation in children. J Pediatr  The pars plana approach is free from all these Ophthalmol Strabismus 2002;39:73-76. disadvantages, though most anterior segment 5. Fujii GY, de Juan E Jr, Humayun MS, et al. A new 25- surgeons are often not very comfortable with it. gauge instrument system for transconjunctival  The preference for the approach also depends upon sutureless vitrectomy surgery. Ophthalmology factors like age at surgery, condition of PC, whether 2002:109:1807-1812, discussion 1813. IOL implantation is intended or not et. 6. Saini JS, Jain AK, Sukhija J, Gupta P, Saroha V.  The current strategy is to follow the limbal approach Anterior and posterior capsulorhexis in pediatric in children >4yrs of age & in all in whom IOL cataract surgery with or without trypan blue dye: implantation has not been targeted. In younger randomized prospectiveclinical study. J Cataract children, the pars plana approach is preffered as it is Refract Surg 2003;29:1733-1737.

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