Search

Purpose: This study compared in vivo crystalline lens shape measurements using B‐scan images from the IOLMaster 700 with phakometry. Methods: Twenty‐four young adult participants underwent IOLMaster 700 and phakometry measurements under cycloplegia (1% cyclopentolate). The IOLMaster 700 generated B‐scan images along six meridians in 30° increments, which were analysed using custom MATLAB software to determine lens surface radii of curvature. Phakometry measurements were obtained using Purkinje images reflected from the lens surfaces. Results: The IOLMaster 700 image analysis method yielded a lower mean anterior lens surface spherical equivalent power (+6.20 D) than phakometry (+7.55 D); however, the two measurements were strongly correlated (R(21) = 0.97, p < 0.0001). The astigmatic power vectors (J0 and J45) for the anterior lens surface were significantly higher for the IOLMaster 700 measurements, with only J0 showing a significant moderate positive correlation (R(21) = 0.57, p = 0.005). For the posterior lens surface, the IOLMaster 700 measurements had a higher mean spherical power (+14.28 D) compared to phakometry (+13.70 D); however, a strong positive correlation (R(21) = 0.90, p < 0.0001) was observed. No significant correlations were noted for posterior lens surface astigmatic vectors (J0 and J45). The IOLMaster 700 estimates for the equivalent lens mean spherical power were slightly lower than those for phakometry, with a mean difference of −0.72 D, and both methods were positively correlated (R(21) = 0.94, p < 0.0001). Conclusions: The findings demonstrate that IOLMaster 700 B‐scan image analysis technique provides similar estimates of lens surface powers to phakometry. These results highlight the potential of the IOLMaster 700 to provide measurements of lens shape, informing future research and clinical use. [ABSTRACT FROM AUTHOR]

Introduction: Despite the known associations between near work and myopia, and retinal image quality and eye growth, accommodation‐induced changes in higher order aberrations (HOA's) and retinal image quality in children with different refractive errors are poorly understood. Methods: Ocular HOA's were measured using a Hartmann‐Shack wavefront sensor (COAS‐HD, Wavefront Sciences) in 18 myopic and 18 age‐ and sex‐matched non‐myopic children during short‐term accommodation tasks (four demands of 0, 3, 6 and 9 D) presented using a Badal optometer. Eighth order Zernike polynomials were fitted across a 2.3 mm pupil diameter to determine refractive power vectors (M, J180 and J45) and the accommodation error, and a 4 mm pupil was used for HOA analyses. Retinal image quality was examined using the visual Strehl ratio based on the optical transfer function (VSOTF) for third to eighth radial orders only. Results: Most refractive error group differences were observed for the 6 and 9 D demands. Myopic children underwent greater changes in with‐the‐rule astigmatism (J180), higher order and third order RMS values, primary vertical (C3−1) and horizontal coma (C31), and several other individual Zernike coefficients compared with non‐myopic children (all refractive error group by demand interaction p‐values of ≤0.02). Non‐myopic children exhibited a greater negative shift in primary (C40) and positive shift in secondary spherical aberration (C60) (both refractive error group by demand interaction p‐values of ≤0.002). The VSOTF degraded for the 6 and 9 D demands in both groups, but the myopic children underwent a greater mean (SE) reduction from 0 D of −0.274 (0.048) for the 9 D demand, compared with −0.131 (0.052) for the non‐myopic children (p = 0.001). Conclusion: These results may have implications for the association between near work, accommodation and myopia development, particularly related to the use of short working distances during near tasks. [ABSTRACT FROM AUTHOR]

Purpose: Near work has been linked with myopia development; however, the underlying mechanism remains unclear. Small increases in axial length during accommodation have previously been reported in adults, and therefore, this study aimed to examine if accommodation‐induced changes in ocular biometry also occur in school‐aged children. Methods: A range of ocular biometric measurements were captured during brief accommodation tasks at four demands (0, 3, 6, and 9 D), in a group of 87 non‐myopic, school‐aged children using a Badal optometer mounted to a non‐contact optical biometer (Zeiss IOLMaster 700, https://www.zeiss.com/meditec/int/product‐portfolio/optical‐biometers/iolmaster‐700.html). Reliable biometry measurements and active accommodation were observed for 76 participants who were included in the analysis. The average central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), anterior segment length (ASL), vitreous chamber depth (VCD), and axial length (AL) were determined for each accommodation demand. Raw measurements of AL and VCD were corrected to account for the effect of LT changes during accommodation. Results: On average, AL increased with increasing levels of accommodation (p = 0.005). The mean (SEM, standard error of the mean) AL increase from 0 D to the 3, 6, and 9 D demands was 4 (1), 8 (1), and 15 (2) µm, respectively. All other biometric parameters, except CCT, changed significantly during accommodation. LT and ASL increased, and ACD and VCD decreased significantly with increasing accommodation (all p ≤ 0.02). A longer baseline AL was associated with greater levels of accommodation‐induced axial elongation at the 9 D demand (p < 0.0001). Conclusions: AL increased significantly during accommodation in children, consistent with previous findings in adults up to a 6 D demand. AL continued to increase for higher levels of accommodation (9 D demand), which children may experience during near tasks. These findings provide further insights into potential mechanisms linking near work, axial elongation, and myopia development. However, no myopic children participated in this experiment; therefore, further research is required. [ABSTRACT FROM AUTHOR]