Predicting the Lens Capsular Bag Size Using Pre-operative Biometry

Aim of this study is to assess whether a high-resolution scan of the crystalline lens before surgery may be helpful in predicting post-operative capsule bag diameter.

Most of the measurement procedures used in this study are non-invasive and all are used in standard routine clinical practice, the benefit/risk ratio appears acceptable. However, a capsule tension ring will be used. A CTR is not used routinely, usually only in cataract operations in which the lens capsule is not stable enough - in other words, for stabilization. The insertion of the CTR is problem-free in most cases. In extremely rare cases, however, the lens capsule may be injured. And document complications will be collected, report them in a final paper. The CTR used in the study is a standard device and CE-marked device. Studies using CTR showed that it is beneficial in difficult cases. Gonioscopy after cataract surgery will be performed after 1 week. At this time point the wound is already sealed and there appears to be no increased risk to the patient. In the first study performed in a similar fashion in 1999 gonioscopy was performed one day after surgery. Aim of this study is to predict the diameter of the capsular bag using pre-operative optical biometry findings. This is a prospective, observer-blind and monocentric study that includes patients scheduled for cataract surgery. Recruitment will take part on the day of pre-assessment. For each patient only one eye will be included. In total 50 eyes of 50 patients will be included, of which at least 5 eyes with an axial eye length below 22.5mm and 5 eyes with an axial eye length above 25.0mm.

Lens thickness, lens shape, anterior chamber depth, axial eye length and angle-to-angle will be used as explanatory variables (independent variables) and the size of the capsular bag will be used as main outcome parameter (dependent variable). We will perform a multiple linear regression analysis (that allows determination of the overall fit (variance explained) of the model and the relative contribution of each of the predictors to the total variance explaine) between the independent and the dependent variable.

Lens thickness, lens shape, anterior chamber depth, axial eye length and angle-to-angle will be used as explanatory variables (independent variables) and the size of the capsular bag will be used as main outcome parameter (dependent variable).

• Prediction of the size of the post-operative capsular bag diameter using pre-operative optical biometry (lens thickness, lens shape, anterior chamber depth, axial eye length and angle-to-angle distance)

Inclusion Criteria: Patient scheduled for cataract surgery Well dilated pupil at the pre-assessment visit (dilated pupil size at least 6.0mm) Age 21 and older Pre-operative visual acuity of at least 0.25 Snellen Exclusion Criteria: Parameters that influence the capsular bag stability (pseudoexfoliation syndrome, St. p. severe eye trauma, Phakodonesis) In women of childbearing age, a pregnancy test will be performed before inclusion into the study.