Are There Changes in the Nerve Fiber Layer (NFL) After Lowering of Eye Pressure?
Condition: Glaucoma
MeSH terms: Glaucoma
Study type: Observational

Summary: 
      The aim of this study was to evaluate structural and functional improvement after lowering
      intraocular pressure (IOP) in patients with glaucoma using Spectral Domain Optical Coherence
      Tomography (SD-OCT), Visual Field (VF) testing, and Visual Evoked Potential (VEP).
    

Detailed description: 
      Glaucoma exhibits characteristic changes to the optic nerve in the back of the eye. The optic
      nerve is formed when fibers that overlay the retina come together. This layer is called the
      retinal nerve fiber layer (RNFL).

      Optical Coherence Tomography (OCT) is a machine that scans eyes and has the capability of
      measuring thickness of various layers in the retina and RNFL. This provides important
      anatomical information.

      VEP (visual evoked potential) is an imaging system that measures electrical signals from the
      eye to the brain by using electrodes placed on the forehead and back of head. This is similar
      in principal to an electrocardiogram of the heart.

      Visual field testing is done to evaluate the extent of side vision loss caused by various
      diseases of the eye, including glaucoma. This testing is performed as you stare at a small
      light directly in front of your eye while lights flash one at a time in every direction on a
      screen surrounding the central light. You push a button each time you see a flash out of the
      corner of your eye.

      Lowering intraocular pressure (IOP) in the eye has been shown to result in reversal of
      glaucoma changes of the optic nerve in some patients. It has also been suggested that
      improvement in function (visual field) has been associated with improved optic nerve
      appearance.

      This study seeks to provide evidence for reversal of disc appearance and visual function
      following IOP lowering interventions.
    

Intervention name(s): Optical Coherence Tomography (OCT); Visual evoked potential (VEP); Humphrey Visual Field (HVF)
Intervention type(s): Diagnostic Test; Diagnostic Test; Diagnostic Test
Intervention description(s): Optical Coherence Tomography (OCT) is a machine that scans eyes and has the capability of measuring thickness of various layers of the retina and nerve fiber layer (NFL).; Visual Evoked Potential (VEP) is an imaging system that measures electrical activity from the eye to the brain by using electrodes placed on forehead and back of the head similar to electroencephalogram (EEG).; Humphrey Visual Field (HVF) is a test done to evaluate how much peripheral (side) vision has been lost due to glaucoma.
Other intervention name(s): OCT; VEP; VF
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Glaucoma patients with intraocular pressure (IOP) between 22 and 32 millimeters of mercury
        (mm HG); greater than 32 mm HG; and with stable IOPs (control group).
      
Keywords: Visual Evoked Potentials; Optical Coherence Tomography; Visual Fields