Speculum-Induced Intraocular Pressure Elevation During Cataract Surgery and Its Association with Axial Length: A Retrospective Clinical Study

Background/Objectives: This study aimed to characterize eyelid speculum-induced intraocular pressure (IOP) elevation during cataract surgery and identify ocular biometric factors that stratify susceptibility to this pressure response. This study was conducted at Zengyo Suzuki Eye Clinic, Kanagawa, Japan. Methods: In this retrospective observational study, we analyzed 100 eyes that underwent routine cataract surgery. IOP was measured immediately before and within 10 s of speculum opening in the seated position using a rebound tonometer. The eyelid speculum was opened to a maximal opening position, and the opening width was recorded. Biometric parameters included axial length (AL), central corneal thickness, white-to-white distance, anterior chamber depth, and temporal angle-opening distance. Associations between IOP elevation and biometric factors were analyzed. IOP elevation rate was quantified as the percentage increase from baseline. The discriminatory performance of axial length was evaluated using receiver operating characteristic (ROC) analysis. Results: Overall, 100 patients (100 eyes) were included in the analysis. Mean IOP increased significantly from 15.75 ± 2.77 mmHg before speculum placement to 21.42 ± 5.54 mmHg after placement. The mean IOP elevation rate was 36.0 ± 27.4%. Shorter AL was consistently associated with a greater proportional IOP elevation. ROC analysis demonstrated consistent stratification of IOP elevation susceptibility by AL (area under the curve [AUC] = 0.645), with eyes shorter than 23.84 mm showing greater pressure elevation (sensitivity, 73.1%; specificity, 56.0%). Eyes in the upper quartile of the IOP elevation rate exhibited relatively greater pressure elevation. Conclusions: Eyelid speculum placement imposes a clinically meaningful IOP load during cataract surgery, with shorter ALs making eyes more biomechanically susceptible to IOP elevation.