New data from a follow-up to the Low Concentration Atropine for Myopia Progression (LAMP) study published in Ophthalmology evaluated the long-term effectiveness of low-concentration (0.05%) atropine over a 5-year period.
Let’s start with the original LAMP study.
This study was a randomized, double-blinded, placebo-controlled trial that examined 438 children with the following criteria:
- Aged 4 to 12
- Myopia of at least -1.0 diopter (D)
- Astigmatism of -2.5 D or less
And the setup?
Researchers randomly assigned participants in a 1:1:1 ratio to apply one drop to both eyes (nightly) with one of the following doses over the study period of 1 year:
- 0.05% atropine
- 0.025% atropine
- 0.01% atropine
- Placebo eye drops
Original outcome measures?
The primary measures included changes in spherical equivalent (SE) and axial length (AL), with their differences among the four dosing groups compared.
So what were the 1-year findings?
The researchers reported that all three atropine concentrations reduced myopia progression with a “concentration-dependent response.”
While all concentrations were well tolerated—with no adverse effect on vision-related quality of life (QoL), “0.05% atropine was most affected in controlling SE progression and AL elongation” over the study’s 1-year period.
0.05% atropine group:
- Mean SE change of -0.27±0.61 D (P < 0.001)
- Mean increase in AL of 0.20±0.25 mm
0.025% atropine group:
- Mean SE change of -0.46±0.45 D (P < 0.001)
- Mean increase in AL of 0.29±0.20 mm (P < 0.001)
0.01% atropine group:
- Mean SE change of -0.59±0.61 D (P < 0.001)
- Mean increase in AL of 0.36±0.29 mm (P < 0.001)
Placebo group:
- Mean SE change of -0.81±0.53 D (P < 0.001)
- Mean increase in AL of 0.41±0.22 mm (P < 0.001)
Note: Visual activity and visual quality of life were not affected in any group.
Any other previous findings to report?
Yes! Three-phase LAMP study also reported 0.05% atropine as being more effective than 0.025% and 0.01% in both SE and AL changes between the groups (which involved 326 of the original 438 participants).
Investigators also found that continued atropine treatment over 3 years was more effective than 2 years of treatment followed by treatment cessation.
Gotcha. Now talk about this new study.
Of the 326 participants from the 3-year LAMP study, 38% (269 patients) completed the 5-year follow-up.
The setup: In the third year, participants receiving the 0.05%, 0.025%, and 0.01% atropine doses were randomized to continue treatment and to end treatment.
During the fourth and fifth years, all participants who continued treatment were switched to a 0.05% dosage; meanwhile, participants who previously ended treatment underwent a PRN retreatment protocol to resume 0.05% atropine.
And the outcome measures?
They included:
- Changes in SE and AL across 5 years in different groups over 5 years
- Number of participants needing retreatment
- Changes in SES and AL in continued treatment and PRN retreatment groups (years 3-5)
And these new findings?
Cumulative mean SE progressions were as follows:
- -1.34±1.40D for initial 0.05% atropine group (P=0.02)
- -1.97±1.03D for initial 0.025% atropine group (P=0.02)
- -2.34±1.71D for initial 0.01% atropine group (P=0.02)
The researchers reported similar trends in AL elongation (P=0.01). They also stated that 87.9% (94/107) of children in the PRN group required retreatment and the proportion of retreatment amongst all dosage groups was similar (P=0.76).
What about SE progression and AL elongation?
SE progressions and AL elongations for the continued treatment and PRN groups for years 3-5 were as follows:
Continued treatment group:
- -0.97D±0.82D SE progressions (P=0.55)
- 0.51±0.34mm AL elongations (P=0.84)
PRN treatment group
- -1.00±0.74D SE progressions (P=0.55)
- 0.49±0.32mm AL elongations (P=0.84)
Any notable limitations?
For starters, participant dropout rate was higher than the researchers preferred. This may have reduced the statistical power and led to bias; however, they noted this dropout rate was not related to the treatment group.
Further, because all atropine groups were switched to a 0.05% concentration after the end of the third year, the researchers could not compare the long-term efficacy of each group.
And since participants in the placebo group were switched to 0.05% atropine from the second year of the study and onward, there was no placebo group over 5 years for comparison.
Expert opinion?
Overall, the study authors stated that continued 0.05% atropine treatment was effective for myopia control in children.
Take home.
The researchers suggest pediatric patients with a high risk for myopia progression may benefit from continued treatment with 0.05% atropine during the first 5 years.