Delayed IOL implantation ensures better refractive outcomes for infantile cataract

The authors report outcomes of secondary IOL implantation in the Infant Aphakia Treatment Study (IATS).

Study design

This secondary analysis of IATS—a multicenter, randomized clinical trial in the United States involving 114 infants who remained aphakic or were randomized to primary IOL placement—evaluated visual and refractive outcomes and adverse events at age 10.5 years in patients who received a secondary IOL.

Outcomes

Nearly all (55 of 57) patients randomized to aphakia with contact lens correction were evaluated at 10.5 years; 24 (44%) of these patients had secondary IOL surgery at a median age of 5.4 years (range 1.7–10.3 years). Mean absolute prediction error was 1.0 ± 0.7 D. The logMAR visual acuity of these eyes was 0.9 (range 0.2–1.7), which was comparable to vision in the 31 eyes still aphakic at 10.5 years. A similar number of eyes in both groups remained stable or had improved visual acuity between the 4.5- and 10.5-year visits. For the 22 eyes that received an IOL after the 4.5-year visit, mean refraction at age 10.5 years was -3.2 D (range -9.9 to 1.1 D) compared with -5.5 D (range -26.5 to 3 D) in eyes with primary IOL (P=0.03).

Limitations

This study has limitations, including the inherent bias in the timing and selection of eyes that had secondary IOL surgery. Surgeons participating in IATS are not necessarily representative of those in the community setting, and the children selected may not represent all children receiving this type of surgery. Study families received significant financial and emotional support that might not be available in real-world settings. In other contexts, children may receive a secondary IOL at a younger age that may yield higher rates of surgical adverse events or greater final residual refractive error. Other factors can influence the decision about whether and when to proceed with secondary IOL implantation.

Clinical significance

Although most patients with infantile cataracts receive an IOL at some point, the timing of implantation is controversial. Prediction error after cataract surgery in children is more variable than it is with adults. Since significant axial elongation occurs in early childhood, pseudophakic eyes can experience large degrees of myopic shift. Despite theories that IOL implantation after 5 years of age may mitigate postoperative myopic shifts, this study shows that the shifts are sometimes greater than anticipated even with delayed surgery. While delayed implantation leads to a more predictable refractive outcome range at 10.5 years, the range of refractive error is still large.

In addition, the results show that it is important to counsel families that visual acuity after IOL implantation is not expected to be significantly different than the visual acuity obtained with contact lens or spectacle use. Interestingly, less than 50% of patients received an IOL by age 10.5 years in this study. Despite the limitations of the study outlined above, the report suggests that there are refractive advantages to delaying secondary IOL surgery until school age. When an experienced surgeon performs the elective surgery after age 5 years, the complication rate is low and there are far fewer adverse effects than when the surgery is performed during infancy.