We highlight intraoperative challenges faced during cataract surgery in eyes of children following glaucoma filtration surgery. The most common intraoperative challenge faced by surgeons in our series of cases was in performing an anterior capsulorrhexis (10/20 eyes), along with an extension of posterior capsulotomy (6/20 eyes) and intraocular lens stability (3/20 eyes).
Certain unique challenges like corneal haze/scarring (impeding visualization during surgery), stretched limbus, a deep anterior chamber with intraoperative fluctuations and a poorly dilating pupil contribute to the difficult surgery.2,7 An enlarged ciliary ring, stretched and lax zonules and capsular bag makes IOL placement and stability very challenging.2,7
In our series, difficulty in the visualization of the anterior capsule despite using trypan blue was noted in 4 eyes. Although the capsulorrhexis was completed eventually, we recommend using a light pipe in the presence of corneal haze to initiate the capsulorrhexis. Difficulty to initiate the capsulorrhexis due to calcification of anterior capsule was noted in 2 eyes. In these 2 eyes, an automated vitrector was used to make the capsulotomy. In one of these eyes, a multipiece IOL was placed in the sulcus, and in the other eye, the initial plan was a lensectomy and hence an IOL was not placed. Maintaining the integrity of the capsulorrhexis was a challenge as well. In 4 eyes an extension of the CCC was noted. In glaucomatous eyes, this is an expected challenge. In children, the anterior capsule is extremely elastic and prone to extension. Inadequate visualization, a fluctuating anterior chamber, and zonular laxity make these eyes prone to extension. In 3 eyes the CCC could be salvaged, in one eye it could not be retrieved and an automated vitrector was used to complete the capsulorrhexis.
The other challenge noted in our series was difficulty in primary posterior capsulotomy. Similar to CCC, poor visualization, instability of the capsular bag makes this step a challenge. In 4 eyes PPC was attempted with an automated vitrector and after making an initial opening in the posterior capsule, a sudden enlargement of the PC opening was noted. In 2 other cases, a manual PPC was initiated which was noted to be extending, and hence PPC was completed with an automated vitrector.
In three eyes, there was superior decentration of the IOL. In both cases, the surgery performed was lens aspiration with IOL implantation with anterior vitrectomy and posterior capsulotomy and IOL was placed in the sulcus. These children were 4 and 6 years old respectively. This is similar to what is reported by Sukhijia and associates. The aforementioned intra-operative factors can challenge the stability of the IOL. One of the techniques to counter this is to make a smaller anterior capsulorrhexis which can cover the optic and this can stabilize the IOL during the fluctuations of the anterior chamber that occur during surgery. We propose performing a PPC in all cases aged less than 8 years. This would reduce the need for a membranectomy as additional procedures can increase the risk of IOP elevation. The choice of IOL we prefer is a 3-piece IOL since the thinner haptic does not rub and irritate the iris like a single piece IOL. Studies have shown that an IOL placed in-the-bag does reduce this risk of iris chafing and chronic inflammation. Kiarudi and associates have used pre-operative ultrasound biomicroscopy to calculate the size of the capsular bag before planning an IOL placement.8
The integrity of the paracentesis is yet another aspect that needs keen attention. Buphthalmic eyes often have a stretched limbus which can lead to fish mouthing of the paracentesis. We noted this in 4 eyes. Gentle handling of the instruments through the paracenteses and suturing these incisions is recommended.
Although there are no studies recommending measures to be taken during pediatric cataract surgery following GFS, Dada and associates recommend the following measures in adults during phacoemulsification.7 These are careful paracentesis, gentle iris handling to prevent inflammation postoperatively, using a dispersive viscoelastic and chilled balanced salt solution to protect the corneal endothelium, a thorough cortical cleanup, and an in the bag IOL placement.
The choice of cataract surgery depends upon the anterior segment findings. Cataract in presence of a hazy cornea, poorly controlled IOP, stretched and lax capsular bag and zonules would mandate utmost care in decision making with lensectomy being a better option.
Cataract surgery in the presence of a filtering bleb can increase the chances of failure of bleb function. Studies done in adults who had phacoemulsification following trabeculectomy have shown through slit-lamp examination, ultrasound biomicroscopy (UBM), and anterior segment optical coherence tomography (AS-OCT) that there is a decrease in bleb height and a progressive flattening of bleb after cataract surgery. This is hypothesized due to the inflammation following cataract surgery, fibrosis under and around the bleb, and injury to the angle following trabeculectomy.9
Our visual outcomes, as well as IOP, remained stable through the period of follow up.
Amongst the 5 eyes where there was worsening of visual acuity, 2 eyes developed retinal detachment in the late postoperative period and 2 eyes had the development of band-shaped keratopathy in the late postoperative period. Besides, one eye developed amblyopia due to poor compliance with glasses. In all the 5 eyes where vision remained stable pre and post cataract surgery, there was pre-existing corneal haze which possibly led to a non-improvement in visual acuity.
To summarize, the use of light pipe in hazy corneas, use of automated vitrector for anterior and posterior capsulorrhexis, a slightly smaller than usual anterior capsulorrhexis, use of a 3-piece IOL and suturing of paracentesis help in minimizing complications and achieving good outcome. Post-operative complications like retinal detachment and band keratopathy are possibilities that need to be monitored and parents need to be counseled as well.
We accept the limitations of our study. It is retrospective and has a small sample size. But what this study adds are the possible intra-op difficulties that need to be anticipated in eyes of children following glaucoma filtration surgery and possible complications.
To conclude, cataract surgery in pediatric eyes is challenging and if you were to consider that these eyes had prior glaucoma surgeries, it has its own set of challenges. Visual outcomes can be reasonably good and require adequate pre-op and Intra op awareness of difficulties and counseling of parents to discuss prognosis.