An experimental investigation of the vision of hyperopes and myopes using a hologram

Abstract

A hologram of a specially designed multivergence target which displays real and virtual objects (numbers) simultaneously has been used to test the vision of various spectacle corrected subjects. Through the hologram, the subjects see standard ‘60-meter’ numbers that have different amounts of blur. It is found that there is a difference between myopes and hyperopes in the amount of positive blur with which they can recognize numbers seen through the hologram and this difference is statistically significant. A similar study was then conducted in white light illumination using the ‘60-meter’ numbers of a standard test chart at 6 meter distance and positive lenses to provide the blur at the eye. This study showed no difference between the refractive groups. Our results indicate that hyperopes may be relaxing their accommodation more than myopes in viewing through the hologram.

Role of Mandelbaum-like effect in the differentiation of hyperopes and myopes using a hologram

“…The differences in the limit of positive blur with which distance corrected hyperopes and distance corrected myopes recognize the large high contrast letters viewed through the hologram is consistent with the results that were obtained on a larger group with a wider range in age and refractive error in our earlier investigation. 1 As reported in our earlier investigation, some emmetropes responded like myopes while some others responded like hyperopes blur of emmetropes and hyperopes and the difference between the mean limiting blur of emmetropes and myopes were not statistically significant. The p value for the difference in the mean limiting blur of emmetropes and myopes was 0.2 and that for emmetropes and hyperopes was 0.19.…”

“…When presented with a distant test chart in white light, both these groups were able to recognize large characters with around þ2 D of blur. 1 So, it appears that the presence of the number with −1 D vergence in the multivergence hologram is influencing the myopes to recognize numbers having only up to þ1 D of vergence in the multivergence hologram. It is as if they are involuntarily focusing onto the number having −1 D vergence and are recognizing the number having þ1 D vergence tolerating þ2 D of blur in Fig.…”

“…Sixteen wooden rods were used to make the three-dimensional target for Experiment 1 and the vergence range of the images seen through the hologram was designed to be in the range of −1 to þ6.5 D in steps of 0.5 D. Refer to our earlier publication for details of the target. 1 …”

“…While there was hardly any difference in the limiting blur for all subjects under cycloplegia, the value of the limiting blur for all subjects was close to 1 D under cycloplegia as against the 2 D of limiting blur that was obtained in white light for all the subjects in our earlier investigation. 1 This can be attributed to the reduced depth of focus and the effects of aberrations arising from the larger pupil size under cycloplegia. In Experiment 1, the average pupil size of all the subjects was 5.1 mm without cycloplegia and it was 7.1 mm in the investigation under cycloplegia.…”

“…1 In viewing through this hologram which is illuminated with light from a He-Ne laser, subjects see an array of positive and negative numbers placed at various distances from the eye. The negative numbers are seen in front of the eye as real objects and the positive numbers relate to virtual objects behind the eye.…”