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BHVI’s Myopia Calculator is the first online toolkit designed to help eye care practitioners effectively communicate projected myopia progression and treatment efficacy to parents and patients.
Building on the exponential increase in the availability of myopia research data, BHVI has upgraded its free online calculator. It now has several new features, including a predictive tool to help clinicians assess a non-myopic child’s risk of developing myopia.1
The online toolkit consists of three calculator tools:
- A traditional myopia calculator for refractive error progression (upgraded to incorporate newly available data);
- A new axial length calculator; and
- A new myopia onset predictive calculator.
All three calculator tools are available on the same website by clicking the appropriate tabs.
The myopia progression and axial elongation calculator tools plot a red line that represents the average myopia progression or axial elongation expected when using standard single vision spectacles. The shaded area around the red line is the 95% confidence interval of the average progression. The red line and confidence intervals are based on published models derived from a large dataset consisting of clinical and population-based studies. Factors that influence the red line are age, gender, ethnicity,2 starting refractive error and axial length.
The green line in the myopia progression and axial elongation calculator tools represents the possible progression of myopia or elongation of axial length if myopia management is adopted. This helps to demonstrate to the parents and/or patients the benefits of slowing myopia with alternative treatments. The green line uses an estimate of myopia treatment efficacy that is based on meta-analyzed absolute reduction in progression (measured in diopters) and absolute reduction in elongation (measured in mm). The meta-analyzed absolute reductions, which are dependent on age, replace the fixed efficacy percentage (%). The range of absolute reduction is the 95% confidence interval derived from meta-analysis data. For ease of communication to patients and parents, the cumulative progression up to 17 years with and without myopia management is computed and presented as a percentage reduction (%). Meta-analysis output and list of publications for each treatment can be accessed using the provided link.
The axial elongation calculator is a new feature added to the online tool, reflecting the increased popularity of axial length measures to monitor myopia progression in children and measure myopia efficacy with treatments. The starting axial length is an additional input required for this calculator.
Myopia management options are also modified to reflect current evidence on treatment options. Low-dose atropine is split into two categories namely <0.02% and 0.02 to 0.05%. Multi segment/lenslet spectacles are split into spectacles with optical elements and spectacles with optical diffusers. Combination treatment is a new option.
A new predictive calculator tool for non-myopic children is also being introduced. This tool computes the likelihood of a non-myopic child becoming myopic within one or two years. The calculator tool computes the likelihood for a given child using the child’s age, gender, ethnicity, parental myopia and refractive error. The two-year likelihood (probability) is compared to the myopia incidence in the general population and represented on a gauge from low to high risk.
These new and enhanced online calculator tools enable eye care practitioners to effectively communicate the risks of myopia progression and the benefits of myopia management to both patients and parents. The suite enables eye care practitioners to educate non-myopic individuals about the risk of becoming myopic and commence personalized preventive measures. These free and easy-to-use calculators will help improve engagement in myopia awareness and treatment options.
The myopia calculator hosted by BHVI is a collaborative effort with input from myopia researchers in Shanghai Eye Disease Prevention and Treatment Centre, China, Ulster University, U.K. and Linnaeus University, Sweden.
References
1 Nina Tahhan, Xiangui He, Kathryn Jill Saunders, Pelsin Demir, Antonio Macedo, Rebecca Leighton, Karthikeyan Baskaran, Sara Jayne McCullough, Karen Breslin, Thomas Naduvilath. ‘Predictive factors associated with incident myopia in childhood’. Invest. Ophthalmol. Vis. Sci. 2024;65(7):161.
2 Thomas Naduvilath, et al. ‘Regional/Ethnic Differences in Ocular Axial Elongation and Refractive Error Progression in Myopic and Non‐myopic Children’. Ophthalmic and Physiological Optics, vol. 45, no. 1, Jan. 2025, pp. 135–51.
