The goal of this observational study is to evaluate the location of phacoemulsification tip measured by intraoperative OCT during cataract surgeries and its impact on early postoperative changes of cornea and visual acuity. The main question it aims to answer is:

In patients with age-related cataracts undergoing phacoemulsification, does the location (supracapsular, iris-lens diaphragm, or endocapsular) of the phaco tip affect postoperative corneal changes and visual acuity at early postoperative stage? Eyes having phacoemulsification for cataracts will receive intraoperative OCT imaging to evaluate the location of the phaco tip during surgery, and corneal changes and visual acuity will be measured postoperatively.

Inclusion Criteria:

• Age ≥ 50 years and ≤ 90 years
• Diagnosis of unilateral/bilateral age-related cataract
• Nuclear grade ≥2 in LOCSIII classification
• Scheduled for cataract phacoemulsification combined with intraocular lens implantation
• Pupil size ≥6mm after dilation
• Corneal endothelial cell count ≥1500 cells/mm²

Exclusion Criteria:

• Diagnosis of severe systemic disease (e.g., severe hypertension or Alzheimer's disease)
• History of ocular trauma or surgery
• Presence of other ocular diseases (such as glaucoma, diabetic retinopathy, or high myopia)
• Other ocular factors that may complicate the surgery (such as small pupil, shallow anterior chamber)

Patients who are planning to receive phacoemulsification combined with intraocular lens implantation for unilateral/bilateral age-related cataract