Introduction

Intraocular lens (IOL) insertion after infant cataract surgery has been an area of much discussion. The Infant Aphakic Treatment Study (IATS)1, 2 has provided some answers to this complex problem for the first 5 years. Clinicians must rely on observational case series to try to elucidate the longer-term outcomes of their treatment paradigms beyond 5 years. We present our refractive and ocular health outcomes from a single surgeon series of 12 eyes where primary IOL implantation was performed.

Materials and methods

A retrospective review of all cases under 12 months of age who underwent cataract extraction by a single surgeon (JRG) between November 2003 and December 2006 at a tertiary referral pediatric hospital was performed. Ethics approval was obtained from the Children’s Hospital at Westmead.

Under general anesthesia, an anterior chamber maintainer with balanced salt solution, added sodium heparin 1 unit/ml, and adrenaline 0.5 ml was used. The surgical steps were: superior corneal 3.5 mm incision, Trypan blue-assisted capsulorexhus (‘push-pull’ technique3), hydrodissection, lens aspiration, and 3-piece hydrophobic acrylic lens (MA60AC; Alcon, Fort Worth, TX, USA) with PMMA haptics implanted in the capsular bag. A primary posterior capsulotomy with limited anterior vitrectomy was performed under the IOL. Wounds were closed with 10-0 vicryl. Finally, a subtenons/subconjunctival injection of Marcaine, cepholothin 125 mg, and dexamethasone 2 mg was instilled.

Postoperative regime was chloramphenicol and prednisolone acetate 1% with phenylephrine hydrochloride 0.12% (Predneferin Forte, Allergan, Parsippany-Troy Hills, NJ, USA) q.d.s. Those with bilateral cataracts had contralateral surgery within 3 weeks.

Intraoperative biometry with A-Scan and hand-held keratometry using the SRK/T formula was performed. Target refraction was selected based on age: children ⩽3 months old were targeted at +9.0 D, those between 3 and 6 months at +6.0 D, and those between 6 and 12 months at +3.0 D.

Statistical analysis was performed with SPSS software (Chicago, IL, USA). Locally weighted scatterplot smoothing (LOESS) and mixed models were created to analyse the association between age and spherical equivalent refraction (SER; SER=sphere+½ cylinder) and cylinder.

Results

Nine patients met the age and entry criteria (Table 1). All patients were systemically well. One child had developmental delay and mild dysmorphic features. All patients required either spectacle or contact lenses for correction of their residual refractive errors.

Table 1 Patient demographics, refractive outcomes, and ocular findings
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Refractive outcomes

Figure 1 demonstrates the change in SER over time for (Figure 1a) unilateral and (Figure 1b) bilateral cases. In both groups, the most dramatic change occurred within the first 2 years of life, followed by a milder change from age 2–4 years and minimal changes thereafter.

Figure 1
figure 1

Change in spherical equivalent refraction (SER) over time in (a) unilateral and (b) bilateral infant cataract patients. A locally weighted scatterplot smoothing (LOESS) line demonstrates the mean decrease in SER over time. The most dramatic change in SER occurs in the first 2 years of life, with a mild change from age 2 to 4 years and minimal changes thereafter.

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We observed an increase in astigmatism with time (Figure 2a for unilateral cases and Figure 2b for bilateral cases). Across both unilateral and bilateral cases, the most rapid change occurred before age 5 (mean change of 0.57 D per year, 95% confidence intervals 0.27–0.87 D, P<0.001) that tended to stabilize afterwards (P=0.1).

Figure 2
figure 2

Change in astigmatism with time in (a) unilateral and (b) bilateral infant cataract patients. All patients except one had an increase in cylinder with time. A line of best fit demonstrates the trend (P<0.001).

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Ocular health outcomes

One sulcus IOL positioning was required because of an adherent cataract-capsule complex. Glaucoma occurred in one child requiring treatment. All other children maintained an IOP below 22 mm Hg.

Lens reproliferation was seen in 7 of 12 eyes (58%) managed with YAG laser.

Two late ocular complications occurred including one dislocated IOL after a fall. A separate unilateral cataract patient developed a choroidal new vessel 4.5 years after cataract surgery, with no clear cause identified.

All children developed strabismus over time manifesting as six exotropias and three esotropias. Nystagmus occurred in three patients.

Discussion

The changes in SER seen in our study reflects the rapid growth in axial length within the first 2 years of life.4, 5, 6, 7, 8, 9 The critical message from our study is that there is a rapid change in refraction in the first 2 years that declines over the following 2 years and tends to stabilize by age 4 years. This implies that frequent refraction and change of glasses/contact lenses are needed in the first 2 years, followed by regular checks (at least 6 monthly) from age 2 to 4 years. Annual refraction checks in stable patients is likely adequate after age 4 years.

Lens reproliferation was the most frequent long-term complication encountered, in keeping with the literature.1, 2, 10, 11, 12 Only a single case of high IOP was encountered. The strabismus rate is higher than previously reported12, 13 but may be reflective of the longer follow-up.

Interestingly, we found an increase in astigmatism with time that has not been reported in the literature. We have no keratometry data available. One theory is the PMMA haptics of the IOL may exert a stretching force on the pliant tissue of the infant eye inducing astigmatism that stabilizes as the scleral rigidity increases. A further conjecture is that the human lens plays an important role in ocular development and an IOL may not balance the cornea leading to astigmatism. Finally, it may be that the results are artificial because of the small numbers. Further studies are needed to explore this finding.