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.
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
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
Cohort
Prospective
cataract surgery
Procedure/SurgeryCataract phacoemulsification combined with intraocular lens implantation
Change in corneal thickness
Corneal thickness measured by corneal endothelial specular microscope
Change in corneal endothelial cell density
Measured using corneal endothelial specular microscope
Best-corrected visual acuity
Measured using ETDRS visual acuity protocol with ETDRS visual acuity chart by a masked examiner
Intraoperative and postoperative complications
Monitored by cataract surgeons using intraoperative OCT and postoperative slit-lamp examination. Complications include Descemet membrane detachment, posterior capsule rupture, incision leakage, and etc.
Position of Phacoemulsification
Swept-source intraoperative optical coherence tomography (SS-iOCT) will be used for real-time measurements throughout the surgery. The imaging depth will be set to 12 mm to ensure full visualization from the anterior corneal surface to the posterior lens surface. During phacoemulsification, a five-line scanning pattern will be applied, with the central line aligned with the phaco tip. The iris-lens diaphragm plane will be used as the reference standard on iOCT images. The phaco tip will be considered to be in the supracapsular space when positioned above this plane, at the iris-lens diaphragm plane when exactly at the plane, and in the endocapsular space when positioned below the plane. The duration of phaco tip manipulation in the supracapsular space, at the iris-lens diaphragm plane, and in the endocapsular space will be recorded throughout the phacoemulsification process.
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