Tropicamide may be considered a viable substitute for cyclopentolate due to its rapid onset of action in controlling cycloplegic refraction(CR), according to the results of a meta-analysis published in the Journal of Optometry.
CR is a procedure to determine refractive status while the ciliary muscles are temporarily paralyzed with cycloplegic agents. The inadequate cycloplegic effect may shift results in an under-plus or over-minus direction.
Negareh Yazdani and his associates conducted a meta-analysis to compare the efficacy of cyclopentolate and tropicamide in controlling accommodation during refraction.
The investigators extracted the data from PubMed, Scopus, Science direct and Ovid databases. The authors included six studies (three randomized controlled trials and three case-control studies)in the meta-analysis.
The drug of choice should have a rapid onset, appropriate cycloplegic effect, and minimum side effects. Atropine is generally considered for its cycloplegic effects, however, its prolonged blur vision, slow onset and long recovery time have limited its application to very specific conditions.
Cyclopentolate is a synthetic antimuscarinic cycloplegic agent and is a widely accepted drug as the first choice for patients of all ages which provides excellent short-term cycloplegia. Its effects begin at 25–75min after administration of the drop and recovery appears through 6–24h later.
Tropicamide, as an alternative, is a synthetic analog of tropic acid and is known as a safe agent for CR. It is characterized by a rapid onset and the cycloplegia effect appears 20–30min after administration. Its recovery appears 6h later.
The analysis showed that tropicamide was effective in adults and also in those with myopia, with only an insignificant mean refractive difference of 0.175 D more plus in the cyclopentolate group. In children and hyperopes, the difference was statistically greater (0.22 D and 0.25 D, respectively). In addition, determination of refractive error by retinoscopy showed greater plus than by autorefraction.
The study concluded that tropicamide can produce adequate cycloplegia in certain populations due to its rapid onset of action.
For reference log on to 10.1016/j.optom.2017.09.001