In a prospective study from LVPEI, Drs. Shreya Gupta, Ramesh Kekunnaya, and others evaluate the myopic shift and visual outcomes among infants who received an intraocular lens (IOLs) or spectacles, after cataract surgery.
Cataracts are usually seen as a disease of the elderly. But over 1 in 10,000 children around the world develop congenital cataracts. Pediatric cataracts are more prevalent in low- and middle-income countries and are one of the leading causes of childhood blindness, making up to 15% of all cases. Cataract surgery in infants (lensectomy) typically involves removing the cloudy lens. After surgery, artificial intraocular lenses (IOLs) may be implanted into the child’s eyes (pseudophakia), or no IOL is implanted (aphakia). In the absence of an IOL, high-powered spectacles or contact lenses are used to help the child see. However, living with aphakic eyes requires a lot of training, persistent rehabilitation, and additional spectacles or contact lens cost. Poor compliance among pediatric patients and their parents can lead to further ocular complications such as amblyopia (lazy eye).
Implanting IOLs can help avoid the downsides of living with aphakia, but a child’s eyes are still growing. Normally, an infant’s eyes start off hyperopic (far-sighted) and as the eyes grow in length (axial growth), the refractive power shifts gradually towards the median (the process is called myopic shift) and stops before the eyes become actually myopic (near-sighted). Implanting an IOL at a very young age (under 6 months) triggers a big myopic shift, causing near-sightedness as the child grows. IOLs with high refractive power increase the magnitude of the myopic shift. If IOLs are to be viable for infants, managing myopia is vital. But predicting the myopic shift is difficult due to the non-linear growth of an infant’s eyes.
In a new prospective study published in the Taiwan Journal of Ophthalmology, Drs. Shreya Gupta, Ramesh Kekunnaya, and others from LVPEI evaluate myopic shift and visual outcomes among infants, 5 years after they underwent cataract surgery. The study included 97 patients (173 eyes). Most of the infants (78%) had cataracts in both eyes and were operated upon at an average age of less than 6 months. Ninety-two of 173 eyes were analyzed for refractive and visual outcomes after five years of follow-up. Seventy eyes (65%) were aphakic while 22 (23%) were implanted with an IOL. Refractive outcome was quantified using best corrected visual acuity (BCVA), with corrective spectacles in logMAR.
Children with an implanted IOL had a higher myopic shift (-9.01+/- 3.11) --over three diopters higher--than those who were aphakic and wore glasses (-5.9+/-5.16). However, those with an IOL had better BCVA at 5 years (0.66 +/- 0.42) than those with aphakia (0.92 +/- 0.44). These findings suggest that implanting IOLs in very young infants is viable and can yield better visual outcomes than aphakia—but only in selected cases-- even after accounting for the greater myopic shift. The authors recommend under-correcting the IOL’s refractive power by +8 to +9 diopters, making the child hyperopic after surgery, to counter the myopic shift.
'Despite the significant myopic shift, IOL implantation is feasible & can be considered, whenever possible in infants undergoing cataract surgery. Overall visual outcome seems to be better with IOL implantation,' notes Dr Ramesh Kekunnaya, Network Director, Child Sight Institute, LVPEI and the corresponding author of this paper.
'This study expands the scope of IOL selection in infants from just age to the size of the eye and the dioptre power of the IOL,' says Dr Goura Chattannavar, consultant ophthalmologist and one of the authors of this paper. 'A range of risks and benefits must be evaluated before a decision is made to implant an IOL in such young eyes. Primum non nocere-first, do no harm-is the rule.'
Citation
Gupta, S., Ramteke, S., Chattannavar, G., & Kekunnaya, R. (2024). Myopic shift, refractive, and visual outcomes after 5 years of infantile cataract surgery: Our experience and review of literature. Taiwan Journal of Ophthalmology, 14(2), 236–241. https://doi.org/10.4103/tjo.TJO-D-24-00030
Photo credit: Ellen Crystal, Seva Canada, WSD Photo competition
