CLAD Deconvolved PERG Responses in Glaucoma Patients

Overview

Glaucoma is a progressive disease resulting in blindness. Determining the onset of the disease is critical so patients may obtain treatment to preserve useful vision. This study will collect data from a population of glaucoma suspects (with positive factors for the disease but with normal vision) along with a population of age matched controls using the pattern electroretinogram (PERG) and other standard eye tests for glaucoma. The PERG measures the function of retinal ganglion cells (RGCs) which come together to form the optic nerve. RGCs may become dysfunctional before dying. The Continuous loop deconvolution technique (CLAD) will be used to extract transient PERG responses in both glaucoma suspects and age matched controls. All patients will be monitored with PERG, Optic Coherence Tomography (OCT) and other ancillary tests over 2 years. CLAD will be compared with conventional techniques of monitoring glaucoma (standard PERG, OCT, visual field etc) to see if the CLAD is better at distinguishing between glaucoma suspects and controls.

Description

The PERG is recorded from small metallic cups taped on the skin or contact electrodes on the face similarly to an electrocardiogram except that the location is the skin around the eyes.

The only physical contact the subject will experience is a gentle cleaning of the skin with an alcohol prep pad. During the test the subject will be asked to look at a visual stimulus display for about 3 minutes. Depending on the experimental protocol, the subject may be asked to either sit during the test or to lie down in a bed. Lying down will cause a momentary increase of your eye pressure similar to the one that occurs during your normal sleep. This may help to understand whether or not your optic nerve functions normally when the pressure in your eye increases.

For OCT evaluation, the pupil will be dilated with drops similar to those used in a standard eye exam. The subject will have to briefly look at a mark inside the instrument one eye at a time.

For Visual field (VF) evaluation, the subject will be asked to look at a fixation mark inside the Visual Field testing equipment and asked to signal when they see small lights in their periphery.

PERG, OCT and VF will be performed during the same day of the visit. If the participant has already done these tests in the past, as part of another study or as part of standard treatment, the results of these tests will be obtained from shier record, and be included in this study.

RISKS

For the PERG, the only significant risk to you is a small chance of skin discomfort from the cleansing agent for skin electrodes, which should go away without treatment. For OCT, there is a rare risk to you of an allergic reaction to the drops used to dilate your pupils. The risk is even lower if you did not have any reaction during your previous eye exams. In case of an allergic reaction, your eye doctor will immediately treat it. If you had previous problems with pupil dilation, you may wish to speak to your eye doctor about the option of doing this additional test. There are no significant risks associated with VF testing

Eligibility

Inclusion Criteria:

1. Age 18 to 85 years, inclusive
2. Refractive errors within -5 to +3 diopters
3. Best corrected visual acuity (BCVA) better than or equal to 20/30 (Snellen)
4. Normal standard automated perimetry (SAP) according to the Ocular Hypertension Treatment Study (OHTS) criteria15 (reliability < 15% on all indices, normality > 5% on all global indices in two consecutive sessions 6 months apart)
5. Minimum untreated Intraocular pressure IOP of 15 mm Hg
6. Glaucoma Suspect Status defined as one or more of the following:
   • Glaucomatous optic disc appearance (vertical cup-to-disc ratio [C/D] ≥0.5
   • Cup disc ratio asymmetry ≥0.2
   • Localized thinning of the disc
   • Presence or history of splinter disc hemorrhage
   • Moderately increased IOP (>21 to <28 mm Hg).
   • Family history of vision loss for glaucoma

Exclusion Criteria:

1. Age-related macular degeneration
2. Diabetes
3. Parkinson's disease
4. Multiple sclerosis
5. Unwilling or unable to give consent, unwilling to accept randomization, or unable to return for scheduled protocol visits.
6. Pregnant or nursing women.
7. Currently using prescribed pressure lowering medicines and unwilling to be withdrawn from them.
8. An OHTS risk score high enough in the judgment of the ophthalmologist or optometrist managing the patient to recommend pressure lowering medicine to the patient and not randomization.
9. An OCT abnormal enough in a pattern consistent with glaucoma.