An opto‐mechanical device for the measurement of ocular rigidity and intraocular pressure

Abstract

Abstract Purpose The purpose of the present study is to demonstrate pilot measurements of ocular rigidity and intraocular pressure (IOP) with a minimally invasive opto‐mechanical device. Methods The device consists of a glass lens that is used to contact and deform the corneal surface, while the force required for this deformation is measured by means of a load cell. An infrared LED is used to illuminate the area of deformation. The area of deformation is measured by sensing the reflected light by means of a quadrant photodiode. All signals are simultaneously recorded for post‐processing. A nomogram (look‐up table) developed using enucleated rabbit eyes is used to convert force‐area data to IOP. Twenty right eyes of twenty healthy young subjects were enrolled in the initial evaluation of the instrument’s measurement. In addition, intraocular pressure provided by the instrument was compared to GAT. Results Twenty young ocular‐disease‐free persons (6 men and 14 women) with a mean age of 30 + 6,2 (mean + standard deviation(SD)) performed a measurement of ocular rigidity and IOP with the above‐mentioned instrument. The average ocular rigidity was 0.562 + 0,254 mmHg/ uL (mean + SD) which in Friedenwald’s notation corresponds to 0,0157 + 0,0071. The average IOP estimated was 21 + 9.3 mmHg (mean + SD). Average IOP using GAT was 18,5 + 3,8 mmHg. Conclusion The calculated values of ocular rigidity are comparable to values reported in the literature. Measurement of rigidity in a simple and non‐invasive manner may improve our understanding significance of this parameter in health and disease.