Ocular aberration may play a role in determining optical quality. Recently performed study reported that ocular aberration of preocular tear film would be important factor in not only diagnosing the dry eye but also determining the efficacy of treatment. Therefore, in this study, the investigators will aim to prove the improvement of quality of vision via ocular aberration changes indirectly after the proper treatment for moderate and severe meibomian gland dysfunction. Also, the investigators will evaluate the changes of keratometric values after treatment for moderate and severe meibomian gland dysfunction, which could be demonstrated by autokeratometry, IOLMaster, Pentacam, and iTrace.
Inclusion Criteria:
(1) stage 3 or 4 meibomian gland dysfunction
Exclusion Criteria: