clinical studies

A Multi-center Study of Visual Acuity Measurements and Patient Satisfaction with a Novel Subjective Point Spread Function Refractor and Standard Manifest Refraction

We have investigated a new refraction system, the PSF Refractor, by Vmax Vision, that does not use Snellen eye charts, and are not limited by a series of lenses with discrete refractive powers. We evaluate the refraction outcome of the PSF comparing to the phoropter manifest refraction. Patients are asked to indicate their preference when they viewed through the optic settings of the PSF refraction end point versus the manifest refraction end point. The Purpose of this study was to determine if a Subjective PSF Refractor can produce better prescriptions and VA for patients when compared to a standard phoropter.

Improving the Speed of Subjective Refraction with a NEW Point Spread Function Refractor

While the standard phoropter is a reliable device for obtaining accurate readings of manifest refraction, the time required for training optometrists to use this device as well as the difficulty of use for the patient and time required to perform the test present significant challenges for optometrists. A new subjective refractor based on point spread function (PSF Refractor™, Vmax Vision, Maitland, FL) allows optometrists to accurately measure manifest refraction more easily and more quickly. The purpose of this study was to compare the performance of the PSF Refractor with that of a traditional phoropter. The study focused specifically on speed of the refractive exam and accuracy of refractive measurements.

A Comparative Study Evaluating Subjective Point Spread Function Refraction Versus Manifest Refraction on Keratoconus Patients

Due to high degree of distortion in keratoconus patients, it is difficult to obtain a reliable accurate refraction. However, patient visual evaluation is essential in monitoring and improving the treatment methods. Traditional phoropter refraction is confusing for patients looking at Snellen letters. The asymmetry of the Snellen letters causes more clarity in certain orientation, depending on patient cylindrical axis. This makes it difficult to decide when some parts of the letters become clearer while others have gotten blurrier. We have investigated a new refraction system, the PSF Refractor, by Vmax Vision, that does not use ETDRS eye charts, and are not limited by a series of lenses with discrete refractive powers. We evaluated the refraction outcomes of the PSF Refractor in comparison to the phoropter manifest refraction.

Comparative Evaluation Vmax PSF Refractor vs. Phoropter at Moran Eye Center

The objective of this study is to compare the amount of time it takes to train an optometric personnel (the participant) to perform Vmax Vision™ refraction verses a standard phoropter refraction. The main premise is to show that the Vmax Vision refraction (test) is more quickly understood, learned and performed at a level equal or better than the control (phoropter). The objective of this study is to compare the subjective Vmax PSF Integro™ daytime refraction results (performed by a novice) to the traditional phoropter daytime refraction results (performed by an experienced refraction technician). The main hypothesis is that technicians that have undergone PSF refraction training will be able to obtain refraction results with the PSF Integro that are equal to or better than those obtained by an experienced refraction technician using a traditional phoropter.

Randomized, Prospective Comparison of Two Methods for Performing Subjective Refraction

The traditional method for performing refractions has remained the same for over 80 years. It consists of a phoropter and a Snellen eye chart. The traditional refraction method has the benefits of the use a simple and familiar eye chart. It is convenient since most already had a phoropter, or a trial frame. However, this method has many limitations. The use of traditional Snellen letters, at a 100% contrast level, do not allow for a maximized visual outcome. It is also easy to over-minus patients. More importantly, there is no direct way to perform a nighttime vision refraction.

We investigated a new method for performing subjective refractions. It use a point spread function (PSF) target. We compared the accuracy of the refraction outcomes and the time to complete the exam between the PSF Refractor and the traditional phoropter. A secondary purpose of the prospective study was to determine when and if patients benefitted from a subjective refractive exam under nighttime vision conditions.