Abstract
Purpose: :
To investigate the influence of cataract density on the measurement of axial length achieved with Partial Optical Coherence Interferometry (PCI).
Methods: :
Retrospective consecutive unselected series of 15 patients (19 eyes) affected by cataract, scheduled for lens phacoemulsification and IOL implant at the Department of neuroscience of Bari University; eight male, seven female, mean age 76.27±6.22 years (range 60-85). For each eye Signal-to-Noise Ratio (SNR) and axial length were measured with PCI (IOL Master, Zeiss). Cataract density was measured by Patient Nuclear Score (PNS), using Scheimpflug imaging (Pentacam, Oculus). All patients had routine phacoemulsification with implantation of an intraocular lens (IOL). They were reexamined 2 to 3 months after surgery and the axial length and SNR were again measured using PCI.
Results: :
Axial length was pre-operatively 23.03±6.22mm (range 21.03-24.87), post-operatively 22.91±1.11mm (range 20.97-24.68). Any statistical variation was found (p=0.74). SNR was before surgery 2.76± 0.87 (range 1.6-5.3), after surgery 6.84±3.4 (range 3-17.9), with a strong variation between the values (p<0.0001). Any correlation was found between SNR and axial length pre-operatively (Pearson r= -0.06, p=0.19) and post operatively (Pearson r=-0.34, p=0.45). Similarly any correlation was found between PNS and axial length measured before surgery (Spearman r= -0.21, p=0.37) and axial length measured after surgery (Spearman r= -0.31, p=0.1). Any correlation was found between pre-operative SNR and pre-operative PNS (Spearman r= -0.05, p=0.85) and between post-operative SNR and pre-operative PNS (Spearman r= -0.05, p=0.85). A strong correlation was found between the pre- and post-operative axial length (Pearson r= -0.99, p<0.0001).
Conclusions: :
The measurement of axial length obtained with PCI is not influenced by lens opacity, indexed by SNR or PNS.
Keywords: cataract • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)