Partial Coherence Laser Interferometry in Highly Myopic versus Emmetropic Eyes

PURPOSE: To investigate the reliability of partial coherence laser interferometry for optical biometry in highly myopic eyes. METHODS: Axial length measurements by the IOLMaster (Carl Zeiss Meditec, Germany) with signal-to-noise ratio (SNR) ≥2 were performed in 52 consecutive myopic subjects with axial length ≥26.5 mm and 45 emmetropic patients before cataract surgery. Axial length measurements and SNR were analyzed and compared among the two study groups. RESULTS: Axial length measurements were feasible in 46 of 52 (88.5%) highly myopic eyes and in 41 of 45 (91.1%) eyes with normal axial length. To achieve two reliable axial length values with SNR ≥2, a mean number of 2.06±0.25 measurements was necessary in myopic eyes and 2.10±0.37 in emmetropic counterparts. Mean SNR after two measurements was 4.98±2.44 in myopic eyes versus 5.56±2.32 in control eyes. Even though successful measurement was independent of preoperative visual acuity, patients with visual acuity better than 20/63 showed significantly higher SNR values. CONCLUSIONS: Partial coherence laser interferometry shows satisfying feasibility and good signal quality for axial length determination in highly myopic eyes with stable retinal condition and clear media.