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:

1. history of previous ocular or intraocular surgery
2. ocular infection, non dry eye ocular inflammation, ocular allergy, autoimmune disease,
3. history of intolerance or hypersensitivity to any component of the study medications,
4. wearing contact lenses during the study period, presence of current punctal occlusion,
5. pregnancy, lactating women, and children.
6. Additionally, patients were excluded if they were using any topical ocular or systemic medication that could be used for the treatment MGD or dry eye, including topical or oral antibiotics, topical cyclosporine A, topical or oral steroids, topical non-steroidal anti-inflammatory drugs, topical ocular allergy medications or artificial tears

stage 3 or stage 4 meibomiang gland dysfunction patients