Cataracts are the leading cause of blindness worldwide, and phacoemulsification combined with intraocular lens implantation has become the most mainstream surgical approach. With advancements in surgical techniques and equipment, this procedure has evolved from a simple vision-restoring surgery into the era of refractive surgery. Patients now have higher expectations for postoperative visual quality, particularly the recovery of early vision, which directly impacts their satisfaction. Intraoperative surgical details have a direct influence on postoperative visual acuity.
Thanks to intraoperative optical coherence tomography (iOCT) technology, surgeons have gradually recognized that factors such as surgical incisions and intraoperative anterior chamber collapse can affect the survival of corneal endothelial cells after surgery, which is directly related to early postoperative vision and patient satisfaction. Swept-source intraoperative OCT (SS-iOCT) has further improved imaging range and clarity, helping us discover that the depth of intraoperative ultrasound energy use (such as cumulative dissipated energy) correlates with postoperative corneal endothelial cell loss. This suggests that compared to performing phacoemulsification at the capsular opening plane or in the anterior chamber, intracapsular phacoemulsification may reduce postoperative corneal endothelial cell loss, potentially leading to better early postoperative vision, which is crucial for patient satisfaction. However, evidence is still lacking.
Therefore, this study aims to compare the effects of intracapsular versus extracapsular phacoemulsification on early postoperative vision, as well as long-term visual acuity, corneal endothelial cells, corneal changes, and the incidence of intraoperative and postoperative complications.
Age ≥ 50 years and ≤ 90 years
Able to cooperate with preoperative examinations
At least one eye meets the study eye criteria
Has the capacity and willingness to provide informed consent
Considered unsuitable by the investigator for participation in this clinical trial for other reasons (e.g., unstable systemic condition, uncontrolled blood pressure/blood glucose, severe cardiovascular disease, renal disease, etc.)
Blood pressure > 180/110 mmHg (systolic >180 mmHg or diastolic >110 mmHg). Patients may be considered for inclusion if blood pressure can be controlled below these thresholds with medication.
History of myocardial infarction or other cardiac disease requiring hospitalization, cerebral infarction, transient ischemic attack, or acute heart failure within 4 months prior to enrollment.
Women with childbearing potential (i.e., currently pregnant, breastfeeding, or planning to become pregnant within the next 2 years). Women of childbearing potential should be asked about the possibility of pregnancy, and the investigator will determine when a pregnancy test is necessary.
Parallel
Supracapsular Phacoemulsification
Procedure/SurgeryDuring phacoemulsification, real-time imaging of the anterior segment was performed using SS-iOCT (Tupai, China), but the surgeon was not able to view the images. The surgeon was instructed to proceed with phacoemulsification as per routine, using phaco energy (i.e., level 3). All other surgical steps were identical to conventional surgery.
Intracapsular Phacoemulsification
Procedure/SurgeryDuring phacoemulsification, real-time imaging of the anterior segment was performed using SS-iOCT (Tupai, China). The surgeon was required to confirm under SS-iOCT guidance that the phaco tip was located within the capsular bag (as judged by two observers not involved in the surgery) before applying phaco energy (i.e., level 3). All other surgical steps were identical to conventional surgery.
The best-corrected distance visual acuity at 1 day postoperatively.
It was evaluated using the ETDRS visual acuity chart by a masked optometrist, with the examination procedure following the standard ETDRS visual acuity testing protocol, and the unit of measurement was logMAR.
Coefficient of variation of corneal endothelial cell size
The percentage loss of central corneal endothelial cell density compared to the preoperative baseline at post-operative day 1 and post-operative
Percentage of hexagonal cells
Central corneal thickness
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