Related Experiment Video
Updated: Jan 26, 2026
A System for Culturing Iris Pigment Epithelial Cells to Study Lens Regeneration in Newt
Published on: June 22, 2011
Relationship Between the Degree of Iris Pigmentation and Corneal Sensitivity to a Cooling Stimulus
Anna M Ntola1, Daniela S Nosch2, Roland E Joos2
1Specsavers Opticians Serpentine Green, Peterborough, United Kingdom.
Purpose:
To explore the relationship between the degree of iris pigmentation and corneal sensitivity threshold (CST) on a variety of different ethnicities, using the air-jet noncontact corneal aesthesiometer and by applying a consistent method of subject iris pigmentation classification.
Methods:
A total of 200 subjects (mean age 23.7 ± 3.1 years, 127 women) participated in this clinical cross-sectional study: 100 whites, 40 Asians, 40 Chinese, and 20 Afro-Caribbeans. CST was assessed within the central cornea using a noncontact corneal aesthesiometer, and the degree of iris pigmentation of each subject was noted according to the Seddon method using a set of graded photographs of iris pigmentation (grades 1-5). Inclusion criteria were absence of ocular disease including dry eye, no contact lens wear, and no use of artificial tears. Statistical testing between ethnicities was made by the pairwise t test with Holm adjustment, and a linear model was set up to analyze the effects of ethnicity and iris grade.
Results:
A moderate trend for increasing CST with increasing iris pigmentation grade for all ethnicities was observed (R = 0.46; P < 0.0001), with CST changing from 0.66 ± 0.16 mbars for grade 1, 0.74 ± 0.18 mbars for grade 2, 0.86 ± 0.31 mbars for grade 3, 0.85 ± 0.32 mbars for grade 4, and 1.08 ± 0.40 mbars for grade 5. This correlation was stronger within the white group, representing the only ethnicity with all iris pigmentation grades (R = 0.50; P < 0.0001).
Conclusions:
There is a moderate relationship between corneal sensitivity and the degree of iris pigmentation, with sensitivity increasing as iris pigmentation decreases. This relationship is stronger within whites.
More Related Videos
04:00Author Spotlight: Establishing a Practical and Cost-Effective Protocol for Corneal Sensitivity Testing in Clinical Settings
Published on: August 2, 2024
04:48Establishing a Severe Corneal Inflammation Model in Rats Based on Corneal Epithelium Curettage Combined with Corneal Sutures
Published on: November 22, 2024
Related Concept Videos
01:24One-Degree-of-Freedom System
A one-degree-of-freedom system is defined by an independent variable that determines its state and behavior. One example of a one-degree-of-freedom system is a simple harmonic oscillator, such as a...
01:02Degrees of Freedom
For example, suppose there are three unknown numbers whose mean is 10; although we can freely assign values to the first and second numbers, the value of the last number can not be arbitrarily assigned.
01:02Degrees of Freedom
For example, suppose there are three unknown numbers whose mean is 10; although we can freely assign values to the first and second numbers, the value of the last number can not be arbitrarily...
02:05Degree of Unsaturation
The degree of unsaturation for hydrocarbons is U = (2C + 2 − H) / 2, where C is the number of carbon atoms and H is the number of hydrogen atoms.
02:44Heating and Cooling Curves
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
02:12Relationship Formation