Agreement and Accuracy of Different Devices for Biometry Measurements in Patients With Cataract (Comparison)

The rationale of this study is to compare repeatability, reproducibility and agreement of three different AS-OCT devices and Pentacam. The investigational devices are approved biometry and keratometry devices to perform biometric/keratometric measurements preoperatively before cataract surgery. The measurements are used to calculate the needed IOL power. Measurements with all four devices will be performed 3 times consecutively by two trained observer. The order of the observer, the order of devices as well as the eye (left/right) is randomized. Examinations will be implemented in accordance with the approved investigational plan on subjects and includes: repeated biometry/keratometry with four different devices

The rationale of this study is to compare repeatability, reproducibility and agreement of both, AS-OCT(s) and Pentacam. In our department three different AS-OCT devices and a HR Scheimpflug imaging device are currently in use for clinical routine to measure the cornea. Among refractive and anterior segment surgeons, there is no preferred and accepted method for accurate measurements of the corneal curvature. The four diagnostic tools are based on different technical and physical imaging principles and to date only limited information on their comparability exist. One advantage of ASOCT represents faster imaging speed when compared to Scheimpflug imaging. Thus, imaging misalignment, segmentation errors and defocus aberration can most likely be avoided by AS-OCT. Chen et al demonstrated that HR Scheimpflug imaging measurements of CCT were systematically higher than the measurements provided by FD AS-OCT. Further, repeatability, reproducibility and agreement of AS-OCT and Scheimpflug imaging device will be assessed during follow-up.

Which eye as well as the order of devices and observer will be randomized. Randomization information will be put in a sealed envelope on screening date and opened right before measurements start.

Patients will be asked to place the chin in position and open their eyes wide. In between measurements, the patient will be arranged so his eyes are in one horizontal line and each time before measurement the patient will be asked to blink several times.

Patients will be asked to place the chin in position and open their eyes wide. In between measurements, the patient will be arranged so his eyes are in one horizontal line and each time before measurement the patient will be asked to blink several times.

The measured lens thickness of each device and the measured lens thickness within one device will be compared

The measured white-to-white distance of each device and the measured white-to-white distance within one device will be compared

Inclusion Criteria: Age-related cataract Age 40 and older (females of childbearing age will be interviewed if pregnancy is possible) Exclusion Criteria: Contact lens wear within 5 days Pathologic changes of the cornea, eye lid or conjunctiva on slit- lamp examination History of corneal ocular surgery Microphthalmus Recurrent intraocular inflammation of unknown etiology Blind fellow eye Uncontrolled systemic or ocular disease