Measurement device and derivation formula for static ocular compliance

Abstract

To introduce a device for measuring static ocular compliance (SOC) and propose a best-fit formula. An observational experimental study involving patients with age-related cataracts was conducted between May 2024 and September 2024. Pearson's correlation analysis was used to screen for potential variables that were significantly associated with the SOC. Then, the SOC at six different height differences (recorded as "Δh") was compared, and the best-fit equations for SOC were screened by linear regression analysis. C_Δh was defined as SOC at height difference of Δh mm. A total of 47 eyes of 47 patients (22 males [46.8%] and 25 females [53.2%]) were enrolled. The mean SOC was (0.846 ± 0.274) µL/cmH₂O, with a 95% confidence interval of (0.813-0.879) µL/cmH₂O, with ocular axial length (AL) of (23.74 ± 1.83) mm and central corneal thickness of (541.13 ± 35.34) µm. Furthermore, Pearson's correlation analysis revealed a significant correlation between SOC and AL (all P < 0.001). Using our device, the best-fit formula can be expressed as SOC = 0.948 x C₆₀₀ + 0.067 x AL (R² = 0.985; P = 0.000), with an optimal height difference of 600 mm. The designed in vivo measurement device can accurately measure SOC and derive a best-fit formula.

Keywords: Best-fit equation; Ocular biomechanics; Ocular rigidity; Static ocular compliance.

Fig. 1

Schematic diagram of static ocular compliance measurement device in vivo.

Fig. 2

Partial details using our designed device for measuring the static ocular compliance. (A) A tiny 1-mm wide incision (white arrow) was made to ensure the impermeability of the entire measurement system. (B) The bubble (red arrow) in the thin soft tube should be as tiny as possible to ensure the accuracy of the measurement. (C) The outer diameter of the thin soft tube was measured at 2.22 mm.

Fig. 3

Static ocular compliance at 6 different height differences. The one-way ANOVA showed that there was no statistical significance between static ocular compliance at 6 different height differences (P = 0.762). ANOVA, analysis of variance. C₅₀₀, C₆₀₀, C₇₀₀, C₈₀₀, C₉₀₀ and C₁₀₀₀ were used to represent the static ocular compliance at height differences of 500 mm, 600 mm, 700 mm, 800 mm, 900 mm and 1000 mm, respectively.