Cataract Surgery With IOL and Management of Posterior Capsule
Elliot C. McKee, MD
PREOPERATIVE CONSIDERATIONS
Cataract extraction with IOL implantation in children is distinguished from that in adults by several logistical, anatomic, and developmental considerations (see Chapter 2):
General anesthesia is required in nearly all cases.
The soft lens nucleus allows lens aspiration with a vitrector or irrigation-aspiration handpiece rather than phacoemulsification.
A high incidence of posterior capsule opacification necessitates the use of a primary posterior capsulotomy unless the patient is able to cooperate with laser capsulotomy.1,2,3,4 There are several methods of posterior capsule management in children, each with benefits and drawbacks (Table 6.1).
Children 7 years of age or older may be able to cooperate with laser posterior capsulotomy if needed.
Higher laser power is needed for pediatric posterior capsulotomy, and children have a higher incidence of reopacification after capsulotomy by any method.
Active or uncooperative children require watertight and secure wound construction, usually augmented by sutures.
An inability to obtain postoperative IOP measurement may lead the surgeon to prophylactically treat postoperative IOP elevations (see Chapter 3).
Infants <7 months of age are typically left aphakic due to the higher incidence of complications associated with IOL placement in this age group (see Chapter 5).
IOL power selection is much more challenging in pediatric patients due to the need to balance current visual function needs with anticipated growth of the eye and change in refractive error (see Chapter 4).
TABLE 6.1. Advantages and Disadvantages of Capsulotomy Techniques | ||||||||||||
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SURGICAL PROCEDURE (VIDEOS 6.1, 6.2)Machine Settings
There are many different machines that can be used to remove pediatric cataracts, but a vitrector has advantages in young children because it can be used for anterior and posterior capsulotomies, as well as anterior vitrectomy.
Each machine has different properties, and the specific settings will depend on the machine used, the gauge of the lumen, the unique properties of the cataract, and surgeon preference.
Vitrector
Lumen
20G to 25G lumen is typically adequate for pediatric cataract removal.
Larger lumens (with larger openings): remove material more efficiently, but can result in more chamber instability.
Smaller lumens: more controlled, but may have more difficulty removing very dense lens material.
23G system can work in most instances.
Cut rate
Higher vitrectomy cut rates:
Smaller and more controlled “bites,” which can reduce clogging of the lumen.
Less traction of tissues.
Smoother capsular openings.
Lower cut rates:
Tough or fibrotic capsule
Larger, denser lenticular fragments.
Higher flow rates and higher vacuum can both increase the material that comes to the port.
Incisions
Scleral tunnel incisions are frequently used in young children because they may be made as wide as necessary for IOL insertion and are easily made secure with nonabsorbable suture. Consider clear corneal incisions in older children who are less likely to rub the eye postoperatively and therefore have a lower risk of wound dehiscence.
Scleral Tunnel
Place a 6-0 Silk traction suture underneath the superior rectus muscle to infraduct the eye.
Create a superior conjunctival peritomy (at least 6-8 mm). The peritomy will need to be larger if planning pars plana posterior capsulotomy to allow room for the pars plana incision, slightly offset from the limbal incisions and scleral tunnel.
Use wet-field cautery to provide hemostasis in a zone extending the width of the peritomy and 3-4 mm posterior to the corneal limbus. Ensure hemostasis in the location of the scleral incision, the pars plana incision (if used), and any sclera through which sutures will be passed.
Use a crescent blade (64 blade) to initiate a superior scleral tunnel. The tunnel must be wide enough to permit entry of the IOL cartridge or folded IOL. A width of 4 mm, depth of 50% of scleral thickness, and location 1-2 mm posterior to the limbus is optimal.
Tunnel forward in the wound using a 66 blade or bent crescent blade. It is important to maintain a consistent width and depth of the tunnel as it extends anteriorly. Avoid manipulating the anterior lip of the tunnel as this can distort its structure. Avoid entering the anterior chamber while initiating the tunnel, as this will impair anterior chamber stability while removing the cataract.
Prior to entering the anterior chamber, test both the infusion and the vitrector to ensure proper functioning and allow the exit of air bubbles from the infusion tube.
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