Evaluating treatment effectiveness in a case series of myopia patients

Purpose: This patient case series describes the response to myopia control contact lens treatments and compares the use of five methods evaluating the efficacy of the treatments.

Methods: Data from the myopia management clinic, Glasgow Caledonian University included age, axial length (AL) spherical equivalent refraction (SER) and treatment (orthokeratology (OK), dual focus (DF) and multifocal (MF) contact lenses (n=5 for each treatment)). Treatment effectiveness was evaluated by five methods (1-4 used AL and 5 used SER): 1.Percentile Method using AL growth curve data, 2.Mean Efficacy Method using AL mean values from literature, 3. Cumulative Absolute Reduction in axial Elongation (CARE) method and 4.Emmetropic Growth Method using emmetropic AL growth as a target. 5.Decrease in rate of SER progression.

Results: The Percentile Method indicated that treatment was effective in 53% of patients: three OK, two MF and four DF patients. The Mean Efficacy and CARE methods indicated treatment effectiveness in 33% and 27% of patients respectively: two OK, one MF and one DF patients. None of the patients met the target for the Emmetropic Growth Method. SER method indicated treatment effectiveness for 20% of patients: one DF and MF patient.

Conclusions: In this case series, emmetropic growth as a target was unobtainable due to modest treatment effects. Using SER alone was not sufficient to detect small treatment effects. Growth curve data were limited when evaluating those with a longer AL and short term treatment effects. The Mean Efficacy and CARE Methods are more suitable method for short term clinical decision making in this case series.