Reproducibility of measurements of ocular pulse amplitude and intraocular pressure using SmartLens (R)

Background SmartLens(R) (ODC Ophthalmic Development Company AG, Zurich) is a contact lens tonometer which allows continuous registration of intraocula r pressure (IOP) and ocular pulse amplitude (OPA) and simultaneous ophthalm oscopy. The purpose of this study was to evaluate the intra- and interobser ver variability and reliability of intraocular pressure and ocular pulse am plitude measurements using SmartLens(R). Methods. To evaluate the intraobserver variability, intraocular pressure (I OP) and ocular pulse amplitude (OPA) were both measured 5 times in 10 healt hy eyes by one observer. To evaluate the interobserver variability, intraoc ular pressure and ocular pulse amplitude were measured by 3 different obser vers in 10 healthy eyes. Data description is based on coefficients of varia tion (SD/mean in %) ,statistical inference on ANOVA-based reliability estim ation. Results. The coefficient of the intraobserver variation was 9.57% for the I OP and 14.5% for the ORA (SD IOP +/-1.64 mmHg, SD OPA: +/- 039 mmHg). The c oefficient of the interobserver variation with 5 replicate measurements was 10.16% for the IOP and 14% for the OPA (SD IOP: 1.83 mmHg, SD OPA: +/-0.4 mmHg). The interobserver reliability was 87% for the IOP and 86% for the OP A. One of the three observers obtained significantly higher IOP and OPA val ues. Conclusions. SmartLens(R) is a reasonably precise and reliable device for I OP as well as OPA measurements but the results were not found to be observe r independent.