Cycloplegic eye drops are as effective as eye patches for the treatment of amblyopia, or lazy eye, the most common cause of visual impairment in children and young adults, a new study claims (Archives of Ophthalmology 2002;120:268-78).
Amblyopia affects up to 3% of the population and results from visual neglect secondary to muscular and refractive differences between the two eyes. Ultimately these differences result in defective visual processing. It is usually treated by placing a patch over the good eye, effectively forcing the lazy eye to work harder and improve.
The greatest benefit from patches occurs when wearing one is begun in early childhood, preferably before the age of 7. While wearing a patch is effective and is the standard treatment for amblyopia, it does have social and psychological drawbacks for children, and compliance can be a problem.
For over a century an alternative treatment for amblyopia has been known. Putting cycloplegic drugs, such as atropine sulphate, into the healthy eye causes blurred vision and loss of ability to focus on different distances, forcing the lazy eye to compensate.
Despite the knowledge of an alternative treatment to patches, few comparative studies have been done. Researchers from the Pediatric Eye Disease Investigator Group, which comprises ophthalmologists and optometrists at 47 centres throughout the United States, as well as at centres in Mexico and Canada, studied 419 children aged 3 to 7 years old with amblyopia who were randomised to treatment with either atropine eye drops or a patch (204 children in the atropine group and 215 in the patched group).
The main outcome measurement was visual acuity after six months in both the sound and amblyopic eyes. Vision was checked initially and after 5, 16, and 26 weeks of treatment.
The researchers found that both methods were effective in reducing amblyopia and improving visual acuity, but that eye drops had a greater compliance potential than patches and were preferred by parents. Visual acuity in the amblyopic eye in the patched group initially improved faster, but after six months the groups did not differ significantly.
Atropine treatment did, however, effect visual acuity in the sound eye at six months more than did patching. Thirty patients (15%) in the atropine group experienced a decrease in visual acuity by one line, compared with 14 (7%) in the patched group. Seventeen patients in the atropine group decreased by two or more lines, compared with three in the patched group. This decrease was probably due to residual cycloplegic effect of atropine, because visual acuity in the sound eye returned to pretreatment levels after completion of treatment.
Another possible adverse affect is retinal damage from prolonged pupillary dilatation. Patients were provided with sunglasses to minimise this possibility. The researchers admitted not knowing long term effects but pointed out that atropine is used chronically in a variety of other ophthalmic conditions without having this effect.
Commenting on the report, Dr Paul Sieving of the National Eye Institute said: "This new study found that atropine eye drops had a higher acceptance rate and better compliance by children and their parents than did patching. This well may become a new standard of treatment for some forms of amblyopia."