Fig. 9.1
A lens with inferior opacification and retinoscopy reflex
If the child does not have a readable retinoscopy reflex and haze covers the pupil, the child should then undergo surgery; otherwise severe amblyopia will develop.
It is advantageous to carry out surgery after the age of 1 month in order to reduce the risk of secondary glaucoma and not later than 7–8 weeks to reduce the risk of grave amblyopia. After 3 months, the child often has a nystagmus if surgery has not been carried out, and reduces the chance of good visual acuity levels.
If the child does not have a readable retinoscopy reflex but the opacity does not completely cover the pupil, then the retinoscopy reflex is adjusted by adding different glasses. Not infrequently, cataract eyes are short and thus greatly hyperopic, but also grave myopia occurs due to a small anterior segment or spherical lens shape. It does not require so many diopters ametropia for the retinoscopy reflex to deteriorate.
If you achieve a retinoscopy reflex with glass then you should refrain from surgery and following the above actions.
Why should you not operate a partial cataract?
The child’s visual development is faster if it is phakic than if it is pseudophakic or aphakic (Fig. 9.2).
Fig. 9.2
Development of visual acuity of children with congenital cataract. Observe the poor VA for eyes with nystagmus and the increasing VA for eyes with no surgery
Unilateral cataracts should probably be operated slightly earlier. Unilateral cataracts are seldom caused by a syndrome and the risk for glaucoma is less (this does not apply for very small eyes).
Intraocular Lens
Video 9.1 : 3D animation Bag in the lens.
The Morcher 89 A IOL (Tassignon IOL, Fig. 9.3) is hydrophilic and called a BIL (Bag in the lens IOL) because the anterior and posterior lens capsules are clamped inside the IOL (Fig. 9.3). There are two sizes of IOL, one for adults and one for children. In the most cases an adult IOL (89 A) is used even in children eyes. In case of small eye and poorly dilated pupil the model 89D is preferred (Fig. 9.4).
Fig. 9.3
The 89 A MORCHER hydrophilic IOL. The IOL has an anterior and posterior haptic and a groove between both haptics (Photocourtesy Morcher)
Fig. 9.4
The normal ocular axial growth curve from Sampaolesi. The scale is logarithmic. Note that on the months scale the months on the left are 2–10 months and in the middle 20–100 months
The advantages of the Morcher 89 A IOL is that no posterior capsular opacification forms, the view to the fundus is excellent. The IOL causes much less inflammation than a usual three-piece IOL. Finally, in case of severe ametropia the IOL can be explanted against a new Tassignon IOL.
Morcher IOL type | Total diameter | Optic diameter |
|---|---|---|
Type 89 A | 7.5 mm | 5.0 mm |
Type 89D | 6.5 mm | 4.5 mm |
Figure 9.4: There are two different sizes of “Tassignon” IOL.
Die IOL has an anterior and posterior haptic (Fig. 9.3). Between both haptics is a lens groove. Both rhexis sheets are located in this groove. Both haptics are located at a 90° angle to each other. The IOL is implanted so that the posterior haptic points towards 6 o’clock.
Target Refraction of IOL
In order to find out the target refraction the normal ocular axial growth curve from Sampaolesi is required (Fig. 9.4) [1]:
Example
Congenital cataract in a 4 month old child, The AXL is measured with 20 mm. The Normal ocular axial growth curve from Sampaolesi (Fig. 9.4) shows now that the AXL will be 23 mm at the age of 80 months (6.5 years). The difference between 23 mm–20 mm=3 mm. Three millimeter equals 9D (1 D=3 mm). The target refraction is therefore +9D.
Remark
Short eyes tend to grow less (require approximately 2D less target refraction); long eyes tend to grow more (approximately 2D more target refraction); Down syndrome eyes tend to grow significantly more (approximately 4D more target refraction) (unpublished results).
Surgical Protocol
Video 9.2 : Child’s eye.
Opening of the limbus with a knife 2.8 mm (eventually 2.5 mm) [1]
Injection of 1.0 ml adrenalin solution (see procedure medication) [2]
Injection of Healon GV for corneal protection [3]
Insertion of the caliper ring type 5 NO Tassignon [4] using the ring caliper inserter (sk-7017 EyeTech) [5]
Opening of the anterior capsule with the capsulorhexis forceps [6] (Ikeda 30° forceps) (Rr. 2268 EyeTech)
Removing the caliper ring
Injection of BSS between the lens and the capsule, hydrodissection [7]
Phaco-emulsion of the lens content [8]
Removing lens remnants with the I/A mode [9]
Cleaning the capsule with BSS using the Helsinki needle (1273E Steriseal)
Injection of Healon GV on top of the anterior capsule [3] (never fill the capsular bag!)
Puncturing of the posterior capsule by using the tuberculin needle or 36G needle [10]
Injection of Healon through the puncture hole within the space of Berger until the size of the blister is slightly larger than the anterior capsulorhexis [11]
Attention not to overfill the space of Berger
Performing the capsulorhexis with the Ikeda forceps [6]
Insertion of the lens with the injector (Medicel Lp 604,410)
Injection of miostat [12]
Removing of the Healon with the I/A mode
Refilling the anterior chamber with BSS and hydration of the corneal wound [9]
Control of the water tightness of the wound
Injection of zinacef solution (see procedure medication) [13]
Fig. 9.5
Surgical tray for congenital cataract (Photocourtesy Morcher)
P.S. In pediatric cataracts the procedure is slightly different
Ring caliper 4.5 mm is used
Two sight ports of 1.0 mm are used for lens removal
Injection of Healon into the space of Berger by means of a 41 G needle (Dorc 1270.0.100)
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