Fluctuations of Anterior Chamber Depth and Astigmatism in Pseudophakic Eyes.

Purpose: To explore the significance of changes in anterior chamber depth (ΔACD) and astigmatism between 4 and 8 weeks following uneventful phacoemulsification.

Patients and methods: Anterior chamber depth (ACD, mm), autorefractometry and subjective refraction were monitored in pseudophakic eyes implanted with non-toric IOLs (group 1, SA60AT, n=36; group 2, SN60WF, n=34; group 3, ICBOO, n=16) and phakic control group (n=30, group 4a, for ACD and autorefractometry) over four weeks. Changes in subjective refractions were compared with repeatability in normal phakic eyes (n=30, group 4b).

Results: Reporting key results (p<0.01), mean (±sd 95% CI) ΔACD values (ACD at start minus ACD at four weeks) were +0.02 (±0.37, -0.16 to 0.08), +0.22 (±0.51,0.05 to 0.39), -0.33 (±0.51, -0.58 to -0.08), -0.02 (±0.07, -0.04 to 0.01) in groups 1-4a respectively. Differences were significant (1-way ANOVA, F=7.02). Pooling data from the pseudophakic eyes (n=86) induced astigmatism (IA) by autorefractometry was significantly greater in comparison with group 4a [-0.78D (±0.67, -0.92 to -0.64) and -0.19D (±0.16, -0.25 to - 0.13)]. IA power correlated with the initial power of refractive astigmatism at 4 weeks (A), [IA = 0.36A-0.30 (r²=0.207) and IA = 0.39A-0.29 (r²=0.232) by autorefractometry and subjective refraction, respectively]. In groups 1-3, vector analysis revealed i) the change in refraction in over 55% of eyes was beyond the 95% confidence interval limits observed in groups 4a and 4b, ii) some significant associations between changes in vectors describing astigmatism with ΔACD and IOL labelled power.

Conclusion: Changes in ACD and refraction still occur four weeks after unremarkable phacoemulsification and the inter-relationship depends on IOL design/type. Other factors, such as tilt or dislocation of the IOL along the X-Y axes parallel to Listing's plane, accompanying changes in ACD are expected to affect the postop astigmatism.