SUBLUXATED LENSES

Figure 1: Optical aberrations induced by subluxated lens crossing the visual axis. Courtesy of Manoj V Parulekar FRCS, FRCOphth

Young children who underwent surgery earlier for subluxated lenses had better mean visual outcomes than those who waited longer between diagnosis and surgery, according to a review of cases treated during 16 years at Birmingham Children’s Hospital, UK. Patients with better visual outcomes also were younger on average at both the time of presentation and surgery.

The results, based on 49 eyes operated in 27 patients, suggest that opting for conservative management of significantly subluxated lenses in the early years of life may increase the risk of poor visual outcomes, Aditi Gupta FRCOphth told the 3rd World Congress of Paediatric Ophthalmology and Strabismus in Barcelona, Spain. This could be in part because the longer the duration of visual blur in the first few years of life, the more it may interfere with visual development during this critical period, she said. (see Figure 1)

The study’s aim was to review management of children with non-traumatic subluxated lenses, and identify factors associated with poor visual outcome, Dr Gupta said. The retrospective case review covered 16 years, and included all patients diagnosed with subluxated lenses with mean follow-up of four years.

Lensectomy was offered to children with significant change in refractive error, the edge of the lens close to the pupillary plane, pupillary block glaucoma, and an inability to correct visual acuity (VA) with refractive correction and amblyopia management.

After lensectomy, patients received aphakic spectacles or contact lenses. Degree of lens subluxation and related complications were noted along with treatments provided, and best corrected visual acuity (BCVA) before and after treatment.

Overall, 36 patients with non-traumatic subluxated lenses in 66 eyes were identified. Of these, 49 eyes of 27 children underwent lensectomy, while 17 eyes of nine children were managed conservatively. Mean age at diagnosis was 4.2 years, ranging from 10 months to 12 years. Marfan disease was the most common presumed cause in 58.5 per cent of cases, with isolated ectopia lentis in 30.5 per cent, homocystinuria in 8.3 per cent and Stickler syndrome in 2.7 per cent.

The younger the age at surgery, the better the visual outcomes. BCVA was worse after treatment in the conservatively managed group than the surgically managed group, Dr Gupta reported. Among the conservatively managed group, 18 per cent achieved BCVA of 0.3 logMAR, or 20/40, or better compared with 55 per cent in the surgically managed group.

Among the surgically managed group, mean post-op BCVA was better among patients with better pre-op BCVA, Dr Gupta said. “In the eyes with preoperative VA less than 0.6, we had a mixed outcome, whereas all the cases with preoperative VA 0.6 or better, had a uniformly good outcome.”

Of the 49 eyes operated, 11 with pre-op BCVA of 0.6 logMAR or better all achieved 0.3 or better postoperative vision. However, among 38 eyes with pre-op BCVA worse than 0.6 logMAR, just 16 (42 per cent) achieved 0.3 logMAR or better post-op, another 10 (26 per cent) achieved between 0.3 and 0.6 logMAR post-op, and the remaining 12 (32 per cent) ended up worse than 0.6 logMAR post-op.

Younger age was also a success factor. Patients who underwent surgery earlier in life had a better visual outcome and this was irrespective of preoperative visual acuity, Dr Gupta noted.

Among the 12 operated eyes ending up worse than 0.6 logMAR, mean age was 3.9 years at presentation and 6.3 years at surgery. By comparison, mean ages in the patients with 10 eyes between 0.6 and 0.3 logMAR and 27 eyes 0.3 or better were about 18 months younger at presentation, at 2.45 and 2.3 years respectively, and more than two years younger at surgery, at 4.2 and 4.1 years.

The interval between diagnosis and surgery was also about seven months shorter in the two better outcomes groups, which were nearly identical at 1.75 and 1.8 years compared with 2.4 years in the poorest outcome group.

RACE AGAINST TIME

These results suggest that earlier surgery for subluxated lenses in young children contributes to better visual outcomes, Dr Gupta said. “Most authors do say that early treatment is beneficial but this is an ongoing debate. It is still not clear exactly when is best to intervene.”

However, she noted that subluxation does progress, and based on this study, pre-op BCVA less than 20/70, or logMAR 0.6, and age of about four years should also be considered as surgical indication because they are associated with better visual outcomes independent of pre-op BCVA.

“It would be nice if we could identify the rate at which the lens subluxates – it would make our lives so much easier. But it is a race against time and a clinical challenge in trying to reduce the risk of amblyopia,” Dr Gupta said.

Aditi Gupta FRCOphth,Manoj V Parulekar FRCS, FRCOphth, Birmingham Children’s Hospital, UK, manoj.parulekar@bch.nhs.uk