Intraocular Pressure (IOP) is the fluid pressure inside an eye (measured in mmHg) and tonometry is the method used to determine the IOP. Normal IOP ranges between 10 and 21 mmHg, with a mean value of approximately 16 mmHg. IOP can be elevated if excess aqueous is produced or if aqueous cannot drain properly. Additionally, IOP is affected by certain medications, particularly steroids. 
      Fedorov Clinic Restore Vision Non Contact Intraocular Pressure Measure

      As a precaution and to help identify early stages of glaucoma, IOP is measured in all routine eye examinations at eye care provider practices and hospitals. Many different versions of tonometers exist. The most well-known method is the non-contact tonometer, which uses a puff of air and detects the force of that air as it reaches the eye. Goldmann tonometry is considered the “gold standard” in tonometry and utilizes a probe to physically applanate the surface of the cornea.  Other contact tonometry devices also exist, such as the iCare tonometer that bounces a small plastic ball on the corneal surface. One of the earliest tonometers (largely unused today) is the Schiotz tonometer, which measures IOP by the amount of corneal indentation induced as a weighted pressure is applied to the cornea.

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      Central corneal thickness – influenced by age, race, and previous corneal surgery – is known to alter IOP measurements. Thicker than average corneas register an artificially higher IOP while thinner than average corneas register an artificially lower IOP. No consensus has been reached for accurately adjusting IOP readings for corneal thickness variations.

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      Though the importance is oftentimes greatly exaggerated, IOP must be monitored and controlled, especially in specific circumstances. Routine eye examinations require a measurement of IOP to ensure the pressure is not severely high or low.

      More frequent IOP monitoring is warranted in cases of glaucoma, a medical condition known as ocular hypertension, and after any invasive eye surgery (such as cataract surgery). 

      Restore Vision Clinic OCT 2

      Electrical Stimulation Therapy and Intraocular Pressure

      Taking into account that Restore Vision Clinic (Berlin, Germany) has and is currently improving functional vision in numerous glaucoma patients – a condition where IOP management remains a major therapeutic goal – the relationship between applied low intensity currents and IOP was comprehensively studied.

      Based on hundreds and hundreds of IOP measurements conducted before and after electrical stimulation therapy sessions, we can assure our patients that our treatment does not elevate IOP and is completely safe for glaucoma patients. Interestingly, our results actually indicated that such stimulation slightly lowers IOP.

      Home tonometer devices are being developed for glaucoma patients to self-monitor IOP. Such devices may include ‘smart’ contact lenses, ocular implants, or easy-to-use tonometers where patients could self-measure their IOP. These devices are still being developed and tested.