Related Experiment Video
Updated: Jun 19, 2026
08:27
Quantification of Oculomotor Responses and Accommodation Through Instrumentation and Analysis Toolboxes
Published on: March 3, 2023
Changes in intraocular pressure and ocular pulse amplitude with accommodation
Scott A Read1, Michael J Collins, Heidi Becker
1Contact Lens and Visual Optics Laboratory, School of Optometry, Queensland University of Technology, Brisbane, Australia. sa.read@qut.edu.au
The British Journal of Ophthalmology
|October 14, 2009
Summary
Intraocular pressure (IOP) significantly decreases with accommodation in both myopic and emmetropic individuals. However, ocular pulse amplitude (OPA) changes differently in myopes, suggesting altered IOP dynamics in myopia.
Area of Science:
- Ophthalmology
- Physiology
Background:
- Accommodation, the eye's ability to focus on near objects, can influence intraocular pressure (IOP) and ocular pulse amplitude (OPA).
- Understanding these changes is crucial for diagnosing and managing visual disorders, particularly myopia.
Purpose of the Study:
- To investigate the impact of accommodation on IOP and OPA in young adult myopes and emmetropes.
- To compare the accommodative response of IOP and OPA between myopic and emmetropic individuals.
Main Methods:
- Pascal dynamic contour tonometer was used to measure IOP and OPA in 15 progressing myopic and 17 emmetropic young adults.
- Measurements were taken with relaxed accommodation and after 2 minutes of near fixation (3 D accommodative demand).
- Baseline axial length and corneal thickness were also recorded.
Main Results:
- IOP significantly decreased with accommodation in both groups (mean change -1.8 mmHg, p<0.0001), with no significant difference between myopes and emmetropes.
- OPA also significantly decreased with accommodation (mean change -0.5 mmHg, p<0.0001).
- Myopic subjects had significantly lower baseline OPA (2.0 mmHg) than emmetropes (3.2 mmHg, p=0.004) and showed a significantly smaller OPA decrease with accommodation.
Conclusions:
- IOP reduction during accommodation is a consistent physiological response observed in both myopic and emmetropic eyes.
- Differences in OPA baseline levels and accommodative changes between myopes and emmetropes suggest potential alterations in ocular biomechanics and IOP regulation associated with myopia.
Related Concept Videos
01:27Open Angle Glaucoma: Treatment
In open-angle glaucoma, the iridocorneal angle remains open, but the trabecular meshwork becomes stiff, slowing down the outflow of aqueous humor. This causes a buildup of aqueous humor in the anterior chamber, leading to a sudden increase in intraocular pressure. The treatment for open-angle glaucoma focuses on reducing the elevated intraocular pressure by either decreasing the secretion of aqueous humor or increasing its outflow.
Drugs such as carbonic anhydrase inhibitors, α2- and...
Drugs such as carbonic anhydrase inhibitors, α2- and...
01:25Glaucoma: Overview
Glaucoma is an eye condition characterized by increased intraocular pressure that damages the retina and optic nerve, leading to irreversible blindness if left untreated. The human eye has various components, including the cornea, iris, pupil, lens, and optic nerve. Aqueous humor is secreted by the epithelium of the ciliary body in the posterior chamber and flows through the trabecular meshwork and canal of Schlemm, maintaining normal intraocular pressure. The trabecular meshwork and the canal...
01:28Angle Closure Glaucoma: Treatment
Angle-closure glaucoma, or closed-angle glaucoma, is an eye condition where the iris bulges out and blocks the iridocorneal angle, resulting in a buildup of aqueous humor and increased intraocular pressure. Immediate medical attention is necessary due to the sudden onset of symptoms. The treatment for angle-closure glaucoma includes short-term and long-term approaches. Short-term treatment involves using eye drops like pilocarpine to lower intraocular pressure by increasing aqueous humor...
01:17Pulse amplitude and quality
Pulse amplitude is a crucial indicator of cardiac health because it provides valuable insights into the strength of left ventricular contractions and the overall uniformity of blood circulation within the vasculature. The strength of the pulse is directly related to the force with which the heart contracts and the volume of blood being pumped.
A weak or absent pulse may indicate reduced cardiac output or poor left ventricular contraction, which can be signs of cardiovascular dysfunction or...
A weak or absent pulse may indicate reduced cardiac output or poor left ventricular contraction, which can be signs of cardiovascular dysfunction or...
01:15Depth Perception and Spatial Vision
Depth perception is the ability to perceive objects three-dimensionally. It relies on two types of cues: binocular and monocular. Binocular cues depend on the combination of images from both eyes and how the eyes work together. Since the eyes are in slightly different positions, each eye captures a slightly different image. This disparity between images, known as binocular disparity, helps the brain interpret depth. When the brain compares these images, it determines the distance to an object.
01:17Measurement of Blood Pressure
Assessing blood pressure is a standard procedure executed in virtually all medical environments. The method utilized today was established over a hundred years ago by an innovative Russian doctor, Dr. Nikolai Korotkoff. The soft ticking noise, known as Korotkoff sounds, heard while taking blood pressure readings results from turbulent blood flow within the vessels. The apparatus required for this procedure includes a sphygmomanometer, a blood pressure cuff attached to a gauge, and a stethoscope.