Jimmy Tse

The usefulness of waveform score from the ocular response analyzer.

Purpose. To study the usefulness of the Waveform Score from the ocular response analyzer (ORA). Methods. Both eyes of sixty-four normal Chinese adults were measured by the ORA. An experienced practitioner who was masked to the score evaluated the waveforms. Four measurements were obtained from each eye, and the average was considered as the gold standard. Agreement was compared for the mean of different multiple measurements to the gold standard. Results. There was no significant difference between the gold standard and the mean of different multiple measurements for all ORA parameters. The Waveform Score of 512 signals (four measurements from each eye of 64 subjects) ranged from 1.58 to 9.06. When the best signal value of four measured signals from each eye was considered, the lowest score was 3.60 from 128 eyes. The lower 10th percentile from all signals had Waveform Scores <3.48. Conclusions. If the Waveform Score provides information on the reliability of the signals, a score <3.50 may indicate an unreliable signal, and the signal should be discarded. We also recommend taking three measurements with all the signals having a Waveform Score of 3.50 or above to increase the precision.

Repeatability of near visual acuity measurement at high and low contrast

Purpose:  The aim of this study was to determine the repeatability of high‐ and low‐contrast visual acuity (VA) measurements at near.

Dynamic contour tonometry over silicone hydrogel contact lens

PURPOSE This study compared the measurements of intraocular pressure (IOP) and ocular pulse amplitude (OPA) using the Dynamic Contour Tonometry (DCT) over silicone hydrogel contact lenses of different modulus. Corneal biomechanics were also measured using the Ocular Response Analyzer (ORA). METHODS Forty-seven young (mean age 22.3 years, standard deviation 1.2 years) subjects had IOP, OPA, corneal hysteresis (CH) and corneal resistance factor (CRF) measured without lens and with two brands of silicone hydrogel contact lenses. Each eye wore one brand followed by another, randomly assigned, and then the lenses switched over. Difference and agreement of IOP and OPA with and without silicone hydrogel contact lens were studied. RESULTS The right and left eyes had similar corneal curvatures, central corneal thicknesses, IOP, OPA and corneal biomechanics at baseline. No significant difference was found in CH and CRF when they were measured over different contact lenses. IOP demonstrated a greater difference (95% limits of agreement: 2.73mmHg) compared with no lens when it was measured over high modulus silicone hydrogel lenses. Agreement improved over low lens modulus silicone hydrogel lenses (95% limits of agreement: 2.2-2.4mmHg). 95% limits of agreement were within 1.0mmHg for OPA. CONCLUSIONS This study demonstrated the feasibility of DCT over silicone hydrogel lenses. Low lens modulus silicone hydrogel contact lens in situ has no clinical effect on DCT.