Fig. 15.1
Primary in-the-bag implantation of a one-piece AcrySof IOL. (a) OVD is injected to inflate the capsular bag; (b–e) A one-piece IOL is implanted in the bag; (f) The anterior chamber is inflated and the incision is sealed
Fig. 15.2
Primary in-the-bag implantation of a three-piece IOL. (a, b) OVD is injected to inflate the capsular bag; (c) A three-piece IOL is implanted in the bag; (d) The anterior chamber is inflated and the incision is sealed
15.2.2.2 Management of the Posterior Capsule and the Vitreous Body
After primary in-the-bag IOL implantation, there are two conditions in need of further management: the posterior capsule and the vitreous body. Firstly, preexisting small ruptures on the posterior capsule with irregular edges should be treated with PCCC that completely envelopes the rupture to prevent radial tearing of the posterior capsule. Anterior vitrectomy following PCCC should also be performed. Secondly, though the posterior capsule is intact, the pediatric patient is too young to conserve the entire posterior capsule without occurrence of secondary opacification. In order to avoid posterior capsular opacification on the visual axis caused by the rapid proliferation of lens epithelial cells along the posterior capsule and the anterior hyaloid membrane, PCCC combined with anterior vitrectomy is also needed to destroy the biologic scaffold for postoperative lens epithelial proliferation [16–18]. PCCC can be performed manually with capsulorhexis forceps or with a radiofrequency diathermy device for capsulotomy. The vitreous body in the central axis is removed with anterior vitrectomy via the posterior capsulorhexis opening. The surgical goal can be accomplished either way, with the selection mainly depending on the surgeon’s experience and the availability of surgical equipment.
15.2.3 Primary Sulcus-Fixated IOL Implantation
In recent years, cataract extraction combined with primary IOL implantation has been widely accepted in clinical practice. However, whether primary IOL implantation is feasible depends on the integrity of the posterior capsule, which has a 0.45–5.2 % rate of rupture [19]. Preexisting posterior capsular defects or large posterior defects due to surgical complications can make it impossible for in-the-bag IOL implantation. In either case, the IOL haptics can be fixated in the ciliary sulcus after regular treatment of the vitreous body, but only on the condition that the rim of anterior capsulorhexis is continuous or there is adequate residual capsule on the periphery. However, IOL implantation is forbidden in cases with severe capsular defects to prevent IOL decentration, tilt, or even dislocation into the vitreous cavity.
15.2.3.1 Surgical Techniques
When the IOL cannot be fixated in the bag and sulcus fixation is adopted, OVD is injected between the peripheral capsule and the iris before implanting the IOL. Firstly, the leading haptic is delivered into the anterior chamber via the incision and guided through the pupil into the ciliary sulcus opposite the incision. Then the IOL optic is gently pushed down into the pupillary zone with lens implantation forceps. The trailing haptic, held in the implantation forceps, is dialed and pressed downward. Then the forceps are released to deliver the trailing haptic into the sulcus after completing the three maneuvers – “push, dial, and press” – which can also be conducted with a Sinskey hook. To ensure the success of the primary sulcus-fixated IOL implantation, two surgical techniques are emphasized: (1) The anterior and posterior capsule should be preserved as much as possible to provide adequate support for posterior chamber IOLs. (2) Sufficient OVD should be timely injected into the anterior chamber, which is important in maintaining normal IOP and preventing vitreous prolapse. Finally, the postoperative inflammatory response in sulcus fixation is stronger in children than in adults. Therefore, some surgeons suggest the IOL optic be captured through the anterior capsulorhexis, with the haptics placed in the sulcus and optic in the bag, which is referred to as optic capture. This technique can ensure the long-term stability and centration of the IOL and avoid the inflammatory response and pigment dispersion caused by the friction between the IOL optic and the uveal tissue.
15.2.3.2 Anterior Vitreous Management
Appropriate management of prolapsed vitreous is the key to reducing the postoperative complications. When removing the prolapsed vitreous, surgeons should first deal with the vitreous incarcerated in the incision, then proceed toward the posterior capsular rupture, and meanwhile try to thoroughly eliminate the vitreous in the anterior chamber. In addition, it is better to use a vitrectomy device with separated vitrector and irrigating cannula, with the vitrector placed beneath the irrigation cannula. It avoids disturbing the vitreous in the vitreous cavity caused by hydration. The vitreous in the anterior chamber and at the margin of the posterior capsular rupture should be thoroughly eliminated so that the shape of pupil remains normal and the healing of the corneal endothelium and the incision will not be affected after surgery. Finally, retained vitreous strands in the corneal incision are identified either by dipping dry cotton swabs on the incision to reveal transparent filaments or by observing whether the pupil is round in shape. In brief, the aim of surgical management of vitreous prolapse is to prevent postoperative complications due to vitreous traction, and intraoperative vitreous disturbance should be minimized.
15.2.3.3 Selection of IOL
Currently, three-piece foldable IOL is the main option for primary sulcus-fixated IOL implantation. The haptics of a three-piece IOL are made from polymethyl methacrylate (PMMA), a material with a certain degree of rigidity and toughness, which can help the IOL remain stable and centered after IOL implantation.
15.3 Secondary IOL Implantation
When planning secondary IOL implantation for pediatric aphakic eyes, three key issues should be considered by surgeons: the space for IOL implantation, the choice of IOL fixation, and the transparency of the visual axis. In addition, the selection of IOL type and fixation are determined by the size of the eye, condition of residual capsule and capsular bag, as well as the severity of posterior synechia.
15.3.1 Secondary In-the-Bag IOL Implantation
Secondary implantation is often conducted years after primary surgery. A randomized controlled trial on different capsulorhexis openings conducted by the authors demonstrated that during primary cataract extraction, the anterior capsulorhexis diameter should be controlled between 4.5 and 5.0 mm, the cortex eliminated thoroughly, and the posterior capsule left intact or with only a small capsulotomy, to lay a solid foundation for future secondary in-the-bag IOL implantation [20]. As tissue and cell proliferation is active in children, the residual lens epithelial cells multiply and the proliferative cortex gradually fills the space between the anterior and posterior capsules. Around the anterior capsulorhexis opening, contact and fibrosis of the capsules give rise to a regenerated ring, that is, the Soemmering ring. If the capsular bag is not reopened and the regenerated cortex in the Soemmering ring is not eliminated, the uneven thickness of the regenerated cortex between the anterior and posterior capsules will lead to uneven thickening of the Soemmering ring, which will not only impose pressure on the IOL but also cause IOL decentration or tilt. In addition, if the capsular bag is reopened but the cortex is not thoroughly removed, prolapsed cortex in the pupillary zone or the anterior chamber might induce an inflammatory response and elevate IOP. In conclusion, there are two key points in secondary in-the-bag IOL implantation. First, in the primary cataract surgery, the capsulorhexis diameter is controlled between 4.5 and 5.0 mm to ensure that enough space is preserved between the anterior and posterior capsules. Second, the potential space is reopened to allow for IOL implantation.
15.3.1.1 Surgical Indications [21]
- 1.
Enough regenerated cortex between the anterior and posterior capsules to separate them.
- 2.
The presence of an intact and centered Soemmering ring (Fig. 15.3).
Fig. 15.3
The formation of Soemmering ring after primary surgery
- 3.
The posterior capsule is intact or with a central defect less than 5 mm in diameter.
- 4.
The pupil is sufficiently dilated without obvious posterior synechia.
- 5.
The zonules are intact with normal elasticity and the capsular bag is stable.
15.3.1.2 Surgical Procedures and Techniques
- 1.
For incision, surgeons might choose from superior corneal incision, limbal incision, or scleral tunnel incision.
- 2.
Adequate OVD is injected into the anterior chamber to fully expose the capsular bag and synechiolysis is performed if necessary. When extensive posterior synechia is encountered, the synechia is excised with Vannas capsulotomy scissors closely along the capsular surface.
- 3.
Conventional in-the-bag IOL implantation: After the capsule is fully exposed, use capsulorhexis forceps, cystotome needle, or OVD to separate the fused anterior and posterior capsules, remove the proliferated tissue on the capsular surface, and reopen the capsular bag. The proliferated cortex is eliminated before injection of OVD to inflate the capsular bag and aid in the subsequent implantation of IOL.
- 4.
Innovative in-the-bag IOL placement with radiofrequency diathermy capsulorhexis device (Fig. 15.4): The capsular membrane is fully exposed with OVD. The radiofrequency diathermy capsulorhexis device is used to perform CCC in the periphery of the Soemmering ring formed by adhesion of the anterior and posterior capsules. The capsular bag is reopened, and the proliferated cortex is removed with irrigation/aspiration after hydrodissection. OVD is injected into the capsular bag, where the IOL is fixated. If posterior capsular opacification is present, the device is used again to perform PCCC. However, the diameter of PCCC should be smaller than that of the IOL optic [21].
Fig. 15.4
Secondary in-the-bag IOL implantation with radiofrequency diathermy capsulotomy of the anterior and posterior capsules. (a) OVD is injected to inflate the anterior chamber and eliminate synechia; (b, c) Anterior CCC is performed with radiofrequency diathermy capsulorhexis device; (d) The proliferated cortex is removed with irrigation/aspiration; (e) The capsular bag is inflated with OVD; (f, g) IOL is implanted in the bag; (h–j) Posterior capsulorhexis is performed with radiofrequency diathermy capsulorhexis device again and fibrosis is removed; (k) Anterior vitrectomy is performed; (l) The anterior chamber is inflated and the incision is sealed
- 5.
If the posterior capsule is not intact and vitreous prolapse occurs intraoperatively, the prolapsed vitreous should be completely removed. The anterior vitreous can be eliminated with an anterior vitrectomy machine. If the machine is unavailable or only a small amount of vitreous has prolapsed, scissors can be used for excision of the vitreous strands. When resecting the vitreous with scissors, the vitreous outside the incision should be removed first. The incision is then checked with cotton swabs to ensure the absence of residual vitreous. Miotic agent is subsequently injected into the anterior chamber and the location of the vitreous strand is determined by the shape of the pupil. A Sinskey hook is inserted through the paracentesis to move the vitreous strand in the anterior chamber toward the pupillary margin until its end can be seen in the anterior chamber. Vannas capsulotomy scissors are inserted to resect the strand at the pupillary margin close to the iris surface until the pupil is round in shape.
- 6.
Miosis, suture closure of the incision, and patching of the eye are performed at the end of surgery.
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