Secondary IOLs in Children



Fig. 10.1
(ac) Opening a Soemmerring’s ring and aspiration of the after cataract. Secondary IOL implanted in the sulcus. Note peripheral anterior synechiae at the 6 o’clock position



Until the late 1990s rigid PMMA IOLs were the standard of care. The stiffness of the haptics in these IOLs prevented their forward movement. Currently most commonly used IOLs are made from flexible acrylic. When these are placed in the ciliary sulcus they are prone to anterior movement caused by the gradually increasing thickness of the Soemmerring’s ring. I have seen this occur in several patients who presented some months after surgery with the IOL optic dislocated forwards into the AC. Examination reveals a distorted, stretched pupil due to entrapment of the optic of the IOL in the pupillary opening. Thus caution should be exercised in the use of this type of lens in the ciliary sulcus.

An alternative option is to open Soemmerring’s ring and aspirate the lens remnants within it to recreate a capsular bag. These residual lens epithelial cells aggregate after the initial cataract surgery between the leaves of the anterior and posterior lens capsule. If the reformed capsular bag has enough residual posterior capsular support, a round edged IOL can be implanted into the bag. If the bag is structurally inadequate to support “in the bag” fixation, the IOL can be placed in the sulcus, which is now deeper because the thick Soemerring’s ring has been removed or debulked.



10.2 Figures Showing IOLs in the Sulcus


IOL design has evolved over the last 20 years. Haptics (as well as optics) in many IOLs are now sharp edged (rather than round edged) in order to prevent migration of lens epithelial cells to the centre of the visual axis between the posterior capsule and the IOL itself. Serious problems have been reported after sharp edged IOLs had been placed inappropriately (or inadvertently) outside of the capsular bag. Never put a sharp edged IOL in the ciliary sulcus. It is likely to lead to serious complications including chafing of the posterior iris pigment epithelium, hyphaema, glaucoma, iris cysts, uveitis and even phthisis (Figs. 10.2, 10.3 and 10.4). An example is a 1 year old girl in whom an Acrysof SA60AT was unintentionally placed in the sulcus, instead of in the capsular bag. She initially developed an iris cyst and later pigment dispersion, glaucoma and uveitis. The eye became blind at the age of 4 and then became phthisical. In the event of difficulties during the insertion of a sharp edged IOL into the bag, I would advise immediate removal of the IOL and substitute placement of a round edged 3-piece IOL (or alternatively a rigid PMMA IOL) in the ciliary sulcus with where possible, capture of the optic in the anterior capsulorhexis (Figs. 10.5 and 10.6).

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Figs. 10.2, 10.3 and 10.4
SA60AT IOL placed in the sulcus leading to iris cyst, iris chafing pigment dispersion, peripheral anterior synechiae, and glaucoma. After removal of the IOL the eye became blind and phthisical


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Figs. 10.5 and 10.6
PMMA IOL placed in the sulcus on top of the Soemmerring’s ring


10.3 Artisan Iris Fixated AC IOL


When there is inadequate capsular support for placing an IOL in the ciliary sulcus, an option is the use of an Artisan iris fixated IOL in the AC.

The Artisan Iris fixated IOL was designed by Jan Worst in 1979 using the concept that the mid-peripheral iris stroma is largely immobile [6]. Over the following decades the use of this IOL, which was initially only recommended for the correction of aphakia, was extended to include other indications such as phakic IOL correction of myopia, hyperopia and astigmatism. Paradoxically, the phakic IOL was given FDA approval, but the original aphakic IOL for the correction of aphakia did not receive FDA approval. However, several centres in the USA are currently evaluating the use of the Artisan IOL to correct aphakia in children. Outside of the USA, large experience has already been gathered with this lens in the correction of aphakia. It has been used as a primary implant in cases of traumatic lens subluxation, ectopia lentis and also for secondary IOL implantation in cases with insufficient capsular support. This anterior chamber IOL is surgically less challenging than scleral sutured or glued PC IOL’s. Table 10.1 compares three types of IOL used for secondary implantation in the absence of capsular support.


Table 10.1
Comparison of three types of secondary IOLs





















































 
Artisan

Angle supported lens

Sclera sutured PC IOL

Safety

Complications limited to technique

Angle related complications

Sutures can erode or brake and unstable refraction

Outcomes

Excellent and predictable

Angle related complications

Lens tilt, hemorrhage and secondary glaucoma

Clinical history

30+ years

Removed from many markets

30+ years

Toric option

Yes

No

No

Suturing IOL required

No

No

Yes

Surgical technique

Easy

Easy

Complicated and extensive

Fixation options

Iris

Angle

Sclera, Sulcus, Iris

Surgical time

10–20 min

10–20 min

Up to 60 + min

The Artisan Aphakia IOL comes in three sizes: the adult lens with an optic size of 5.4 mm and overall diameter of 8.5 mm and two pediatric sizes each with 4.4 mm optic sizes but either a 7.5 or 6.5 mm overall diameter. In the author’s experience the pediatric sizes are needed only in cases of microphthalmia. A major advantage of the Artisan IOL over a scleral-sutured PC IOL is that it can be relatively easily removed and exchanged in cases of large myopic shift due to excessive or unanticipated axial elongation (Figs. 10.7 and 10.8).

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Fig. 10.7
Artisan aphakia IOL 1 day after surgery


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Fig. 10.8
Artisan aphakia IOL 10 years after surgery

Before using the Artisan IOL a surgeon needs to become certified by the manufacturer (www.​ophtec.​com). The technique used for implantation is a delicate bimanual procedure, for which training in a wet lab is required. It is important is to preplan the enclavation sites of the haptics. The IOL is inserted through a corneal incision and once it is in the correct position the surgeon holds the IOL for stabilization with forceps while with the other hand uses an enclavation forceps or needle to push midperipheral iris tissue through the slit of the haptics. It is important to ensure that an adequate amount of iris tissue is enclavated. If the iris tissue is stiff, the enclavation needle can be used with additional vacuum from an attached 1 cc or 3 cc syringe with extension tubing. During enclavation an assistant is instructed to withdraw the plunger on the syringe as required, so that the surgeon can simultaneously aspirate a small portion of iris tissue to facilitate enclavation (see Fig. 10.9). Once a small portion of iris tissue is caught between the claws of the haptic, it is easier to enclavate more iris strands as needed. When the enclavation is too large, tissue can be released by pushing on one leg of the claws. My preference is to start with nasal enclavation in non-dyscoric eyes since the pupil is more nasally oriented in most eyes. The nasal enclavation site should be chosen carefully, avoiding larger blood vessels. At the temporal side of the pupil more iris tissue is available to produce a well-centred enclavation. The surgeon should avoid under and over-enclavation of iris tissue. Too little enclavated iris runs the risk of the haptic losing grip and subsequent dislocation of the Artisan IOL, while too much iris enclavation will cause pupil distortion. The second haptic is enclavated 180° across on the other side of the iris. Good centration over the pupil is also crucial. The angulation of the Artisan IOL should be checked. When using the Artisan IOL in the anterior chamber, the haptics should have posterior angulation whilst retropupillary use requires anterior angulation (See Table 10.2).

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Fig. 10.9
Use of a syringe with extension tube and enclavation needle. Additional suction can facilitate iris enclavation

Nov 21, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Secondary IOLs in Children
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