The purpose of this study is to evaluate the safety and efficacy of staged and combined phacoemulsification with intraocular lens implantation and Descemet membrane endothelial keratoplasty (DMEK) to treat cataract patients with corneal endothelial dysfunction. Surgical and postoperative complications, visual acuity and corneal endothelial cell density are evaluated.

The prospective, randomized, controlled study involves the enrollment of cataract patients with corneal endothelial dysfunction. All the patients will be randomly assigned with equal probability to the following two groups: 1. Staged group: phacoemulsification + IOL implantation is performed individually and DMEK is performed secondarily according to the corneal status of patients. During cataract surgery, viscoelastic materials and anterior lens capsule are used to protect the compromised corneal endothelium during phacoemulsification. After phacoemulsification and removal of all the lens material, a one-piece foldable IOL is implanted into the lens capsule. 2: Combined group: phacoemulsification + IOL implantation and DMEK is performed simultaneously. Standard procedures of phacoemulsification + IOL implantation are the same as in the staged group.

Patients enrolled into the study will be followed for one year and will have study visits at 1 day, 1 week, 2 weeks, 1 month, 3 months, 6 months and 12 months after each surgery.

Inclusion Criteria:

1. Subjects are older than 18 years.
2. Subjects have corneal endothelial dysfunction combined with cataract.
3. Subjects have mild to moderate cortical and/or nuclear cataract.
4. Subjects are able and willing to provide informed consent.

Exclusion Criteria:

1. Subjects have corneal stromal opacity and/or neovascularization.
2. Subjects have other intraocular disease that disturbs visual rehabilitation.
3. Subjects have corneal infection, perforation or scarring.
4. Subjects are pregnant.
5. Subjects have concurrent disease that could confound the response to therapy.
6. Subjects are unlikely to comply with the protocol or likely to be lost to follow-up.
7. Subjects have known hypersensitivity or intolerance to the proposed therapy.
8. Subjects use concomitant therapy that affects either tear function or ocular surface integrity.
9. Subjects have had surgical or other manipulation of the eye that could confound the outcome parameters or interfere with the mechanism of action of the proposed intervention to be studied.