Age-Related Corneal Sensitivity assessed with a modified BHVI-Belmonte Aesthesiometer: a preliminary study

Abstract

 

Purpose

 

The BHVI-Belmonte aesthesiometer (Br J Ophthalmol 2004;88:1547-1551), an air/CO2 jet instrument developed to allow stimulation of the ocular surface using distinct mechanical, chemical, and thermal stimuli, was modified to improve the precision of stimulus localization, distance between the ocular surface and the instrument probe, and stimulus delivery.

 

Methods

 

To improve stimulus localization, probe distance and stimulus delivery, the aesthesiometer was modified with the addition of dual cameras (1MP, 15fps) focused on the OS and OD corneal surface, blue LED illumination for fluorescein staining, and the original incandescent illumination was replaced with a user dimmable LED (6000mcd, 5900K, Super Bright LEDs Inc, St Louis, MO). Fixation lights mounted on the instrument housing enabling simple adjustment to the stimulus location were enhanced by making them user selectable in 4 regions (corneal center, mid-periphery, limbus and anterior conjunctiva) in all 4 quadrants. A PC-based graphical user interface (National Instruments, Austin, TX) was designed to record the video and flow volume data, track the interval between stimuli, and calculate the flow volume rate for succeeding stimuli based on subject’s sensation response utilizing an unequal staircase algorithm. Measurements were collected under a VA IRB on 6 healthy subjects, 2 males, 4 females (age 22-63). Sessions were held at the same time of day, each subject was measured 2 times with an interval between data collection of 32 days ±15.

 

Results

 

Subjects were found to have a mean predicted corneal sensitivity threshold of 47.9±14 (ml/min), the Cronbach's alpha was 0.75, indicating good reliability and showed positive statistically significant correlation with age (r = 0.933, P=0.002).

 

Conclusions

 

Modifications to the BHVI-Belmonte Aesthesiometer enhanced the precision of stimulus localization, distance between the ocular surface and the instrument probe, and stimulus delivery and the preliminary data indicate a correlation between age and corneal sensitivity.

 

 

BHVI-Belmonte aesthesiometer

 

 

Age Related Influence on Corneal Sensitivity.

 

Keywords: 486 cornea: tears/tear film/dry eye