DEVELOPMENT OF A CONVENIENT SYSTEM FOR MEASURING FORWARD LIGHT SCATTERING FROM INTRAOCULAR LENSES

Abstract

 

Purpose

 

Forward light scatter from intraocular lenses (IOLs) has been measured in a wide angle range using a goniometer with a photo-detector. The equipment is expensive and inconvenient for measuring a narrow angle range. The narrow angle light distribution has sufficient information to estimate the degree of scattering and to imagine how the vision is affected by the scattering. We developed a new convenient system for measuring the front scatter from IOLs.

 

Methods

 

The equipment was comprised of a model eye and a charge-coupled device (CCD) camera. IOLs were placed into the water cell of the model eye. The images of the model eye are captured by the CCD camera. The images of a high-intensity white light-emitting diode (LED) were obtained by the CCD camera by changing the shutter speed from slow (1/30 sec) to high (1/40,000 sec). The intensity distribution of the scattering light was obtained by reading the pixel values of the images. IOLs that were studied were a clear IOL(VA-60BB,HOYA®), a clear IOL with a scattering filter (Black Pro-Mist3, Tiffen®) having the distribution of artificial cataract eyes and the distribution of the light scattering of extracted calcified IOLs(H60M,Bausch & Lomb®)

 

Results

 

The light intensity of the clear IOL was lowest at the angle of -5 to 5 degrees (Fig. 1). The difference in the intensity ratio between the center and the periphery at the angle of 2 degrees was 1:10-5. This ratio was almost the same ratio obtained by using a goniometer with a photo-detector (1). The inner reflectivity of the CCD camera was sufficiently low for measuring the light scatter from IOLs. The intensity of the clear IOL with a scattering filter at the angle of 2 degrees was 10 times that of a clear IOL. The intensity of the extracted highly calcified IOL was higher than the clear IOL with a scattering filter.

 

Conclusions

 

These results indicated that the proposed system can measure the distribution of the light scatter from IOLs, which will be useful in research. Reference 1. Kamal K. Das, et al Technique for measuring forward light scatter in intraocular lenses J Cataract Refract Surg 2013; 39:770-778

 

 

Fig.1 Point Spread Functions of the clear IOL with and without a scattering filter and two calcified IOLs with different scattering levels.

 

Keywords: 567 intraocular lens • 439 calcium