| Name | Info | Provider | Link |
|---|---|---|---|
| Refractive Errors | free resource | MedlinePlus Health Information | https://medlineplus.gov/refractiveerrors.html |
| subscription/membership/fee required | Ovid Technologies, Inc. | http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=19516144.ui | |
| subscription/membership/fee required | Wolters Kluwer | https://doi.org/10.1097/ICL.0b013e3181abb5bb |