Evaluation Of Optical Quality Of Rgp Contact Lens Wearers Using Continuous Measurement Method Of Oqas

To correct refractive error, spectacle correction and contact lens correction are safe and reasonable correction methods. However, it is known that some contact lens wearers experience dry eye symptoms. Depending on the severity of the symptom, dry eye affects the instability of the tear film, leading to decreased vision and astigmatism. In this study, the difference between the naked eye and optical quality was compared and analyzed through RGP(Rigid Gas Permeable) contact lens correction, and the optical quality was segmented by time by continuously observing the point spread function (PSF) and objective scattering index (OSI value) on the retina.

In this study, the OQAS test was conducted on 69 subjects who did not have eye diseases that affect vision(cornea, lens disease, etc.), were not diagnosed with dry eye syndrome, and had a subjective corrected visual acuity of 20/20 or better. 

All subjects were tested for OSI(objective scattering index), MTF(modulation transfer function) and Strehl ratio over time immediately after the blinking with naked eyes and wearing RGP contact lenses. The test was performed 10 minutes after wearing the lenses, taking into account reflex tear secretion immediately after wearing the contact lenses. The OQAS(optical quality analysis system) device was used to measure the objective scattering index in 0.5-second increments from 0.5 to 19.5 seconds using a non-invasive method that did not use topical anesthetics. 

As a result of measuring the objective scattering index from 0.5 to 19.5 seconds using the OQAS optometry device, the average OSI value within the measurement time was higher for contact lenses than for naked eye in all patients (p<0.05). In addition, in the naked eye condition, the scattering index was stable until 19.5 seconds from immediately after the eye, but in the contact lens wearing condition, it was generally stable up to 4.0 seconds in all patients, but there after, significant changes in OSI were observed at different time points for each individual.

Even with 20/20 visual acuity due to wearing contact lenses, the baseline objective scattering index value was higher than that of naked eyes. A large change in the scattering index measured continuously over time was observed after 4 seconds. Using OQAS, it was possible to quantitatively evaluate the optical quality of contact lens wearers over time.