This project aims at non-progressive keratoconus patients with unsatisfactory visual acuity corrected by spectacles, and explores the effectiveness and maintenance of visual acuity improved by perceptual learning.

Inclusion Criteria:

1. Aged 9 years or older;
2. Has been diagnosed as Keratoconus,BAD-D≥2.6;
3. Change of Kmax < 1.0 D and change of BAD-D <0.4175 betweem the last two Pentacam result;
4. The best corrected visual acuity of both eyes was between 0.1 and 1.0;
5. Has voluntarily agreed to participate in the study by signing the statement of informed consent.

Exclusion Criteria:

1. Has history of acute keratoconus;
2. Has other eye diseases or other diseases/conditions causing vision loss;
3. Has eye surgery history in the past 1year;
4. Is currently using local/systemic medications or other interventions that may affect visual function;
5. Receiving other treatments that may affect the results of this study, such as contact lenses during the study;
6. Has any known neurological diseases;
7. Participating in other studies currently that may affect the results of this study;
8. Study other reasons that the physician considers inappropriate for inclusion in the program.