Combined Atropine With Orthokeratology in Childhood Myopia Control (AOK) -A Randomized Controlled Trial
Condition: Myopia
MeSH terms: Myopia
Study type: Interventional

Summary: 
      This study aims to compare effects in retardation of myopia progression of combined ortho-k
      and 0.01% atropine therapy with those of ortho-k alone.Myopia control methods mainly focus on
      optical and pharmaceutical interventions . Currently, overnight-wear orthokeratology
      (ortho-k), is used extensively in Hong Kong with approximately 50% retardation effect.
      Pharmaceutical methods have focused on the use of atropine eye drops to slow myopic
      progression.The use of 1% atropine was limited by the manifestation of side effects and
      rebound effect.However, both side effect and rebound effect was minimal with 0.01%
      atropine.It was suggested that 0.01% was the optimum concentration for controlling myopia.The
      mechanisms of neither ortho-k nor atropine in myopia control are fully understood.It is
      believed that ortho-k and atropine act via different mechanisms.It is possible that by
      combining these two methods, additional retardation of myopia progression could be achieved.
    

Detailed description: 
      Although it is believed that myopia is the result of an interplay between genetic and
      environmental factors and its progression has been attributed to the lack of outdoor
      activities and intensive school work, myopia control methods mainly focus on optical and
      pharmaceutical interventions. Use of bifocal and multifocal lenses have been shown to be
      ineffective in myopia control. Specially designed soft contact lenses for myopia control have
      recently been launched, but their effectiveness has yet to be confirmed. Currently,
      overnight-wear orthokeratology (ortho-k), which involves reshaping the cornea by overnight
      wear allowing for improved, frequently unaided, vision during the day, is used extensively in
      Hong Kong. Approximately 50% retardation in axial length elongation was observed in studies
      of patients receiving ortho-k (LORIC study, 46%, ROMIO study,43%, and TO-SEE study, 52%).

      Pharmaceutical methods have focused on the use of atropine eye drops to slow myopic
      progression. The use of 1% atropine was first suggested in the 1990's, but its application
      was limited by the manifestation of side effects such as pupil dilatation and loss of
      accommodation. The effectiveness of lower concentrations (0.5%, 0.1% and 0.01%) have been
      evaluated in a recent five-year randomized clinical trial, where the authors reported that
      0.01% atropine once daily was effective resulting in about 50% of spherical equivalent
      reduction. However, this was as a result of one year (3rd year) discontinuation of atropine
      in the five-year study. Rebound effect was minimal with 0.01% atropine and higher dosages
      were associated with more manifest rebound effects, which appeared to negate former myopia
      retardation effects. Only 24% of those receiving 0.01% progressed 0.50D or more after
      discontinuation for one year. By contrast, proportion of children progressed 0.50D or more in
      0.5% and 0.1% groups were 59% and 68% respectively. Moreover, use of 0.01% atropine showed
      sustained myopia reduction with clinically negligible effects on pupil dilatation and loss of
      accommodation. The authors suggested the use of 0.01% as the optimum concentration for
      controlling myopia.

      The mechanisms of neither ortho-k nor atropine in myopia control are fully understood. It is
      believed that ortho-k and atropine act via different mechanisms, with ortho-k slowing myopia
      progression by reducing peripheral hyperopic defocus, while atropine exerts effects on
      anti-muscarinic receptors of the retina and sclera. However, some subjects respond poorly to
      either atropine or ortho-k, as demonstrated in clinical trials, suggesting that a single
      treatment may be not enough. It is possible that by combining these two methods, additional
      retardation of myopia progression could be achieved. In this randomized trial, we will
      explore the effectiveness of combination of ortho-k and atropine therapy, and evaluate
      additional effects by comparing the combination with ortho-k treatment alone.
    

Intervention name(s): 0.01% atropine eye drops; ortho-k
Intervention type(s): Drug; Device
Intervention MeSH terms: Atropine; Ophthalmic Solutions
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Myopia control,ortho-k, atropine eye drops, children