What to expect
The following services are available for patients seen in the Ophthalmic Genetics Clinic. Please note that recommended testing may take more than one day to complete. When possible, patients should complete recommended testing prior to the day of the eye exam.
- Eye exam
- Genetic counseling and genetic test coordination
- Visual field testing
- Genetic Testing
- Color vision testing
A comprehensive dilated eye exam appointment typically begins with a short work-up with the ophthalmic technician. The technician reviews medical history current medications, measures near and far visual acuity, performs a manifest refraction (which determines the need for glasses), tests ocular pressure and color vision.
After the technician is done, the doctor performs an examination of the entire eye, with particular focus on the back of the eye (retina and macula). After the exam is complete, the doctor meets with the patient to review the results of the exam (and tests, if done), discuss the diagnosis, and make recommendations for care.
How to prepare: Patients having an eye exam in our clinic should expect to be dilated and should bring a list of current medications to their appointment.
Genetic counseling and genetic test coordination
Genetic counselors are health professionals with specialized training to provide information and support to individuals and families with genetic conditions. They provide education about inheritance, genetic testing, care management, prevention, resources, and research. Our counselors' primary roles include collecting a 3 generation family histories, reviewing medical histories, coordinating commercial genetic testing, discussing inheritance patterns and recurrence risks, connecting patients with community vision resources, and inviting patients to participate in genetic research studies.
In addition, the genetic counselor communicates genetic test results with patients and referring providers, and correspond regularly with researchers to initiate and maintain close collaboration on genetic studies.
How to prepare: Patients meeting with a genetic counselor should prepare to discuss a detailed family history focused on eye health and bring copies of relevant genetic test results.
Visual Field Testing
Visual field tests measure a person's peripheral (or side) vision as well as determine if there are blind spots in their central vision. Visual field testing requires In our clinic, we test the visual field much more extensively, using an Octopus visual field analyzer. which can measure all areas of the visual field in one test. The Octopus visual field test takes approximately an hour and a half to complete.
How to prepare: Many individuals with a retinal dystrophy or degeneration will experience loss of their. Individuals with macular dystrophy may have blind spots in their central vision. In clinic, we measure this loss with a test of the visual field. Many ophthalmologists and some optometrists use visual field testing machine, usually the Humphrey visual field analyzer. Humphrey visual fields are very good for screening patients to determine whether a given individual has peripheral vision loss or blindspots.
Individuals with a known or suspected retinal disease will probably be scheduled for an electroretinogram (ERG). The electroretinogram measures the electrical impulses of the retina in response to light. Because the ERG measures the actual cells of the retina, it provides an extremely valuable objective measure of the disease state.
There are two major types of ERG;the full-field ERG, and the multifocal ERG. The full-field ERG measures the responses of the rods and cones as an average across the entire retina. The multifocal ERG measure local responses across the central 24 degrees. Prior to your appointment, the coordinator will determine whether you need a full-field ERG, multifocal ERG, or both.
The full-field ERG takes nearly two hours to perform, including 45 minutes of dark adaptation, where the patient sits (or sleeps!) in a dark room. The multifocal ERG is done in a light environment, and takes just 45 minutes.
Some patients with symptoms of a macular dystrophy will be scheduled for a similar test called an electro-oculogram (EOG). The EOG takes one hour.
Genetic testing is becoming increasingly vital to the diagnosis and management of retinal dystrophies. Patients who are interested in genetic testing to confirm their diagnosis can have their blood drawn on site by a trained phlebotomist. Children undergoing sedated exams or tests can have blood drawn by the anesthesiologist or anesthesia nurse while under sedation. Individuals choosing to participate in one of our genetic research studies can also have their blood drawn by one of our phlebotomists at the conclusion of the appointment. Some genetic tests can be done using a saliva kit.
Participation in genetic research studies is always voluntary.
Many patients will have photographs taken of their dilated eyes. With specialized cameras, our photographers can accurately document the appearance of individualized structures of the eye, including the retina, macula, and optic nerve. The photographs serve as a baseline for comparison in the future, and can effectively allow the physician to later determine whether or not the disease has progressed.
Color vision testing
Our visual function service provides detailed color vision testing, used for the diagnosis of certain inherited disorders of color vision. The time required for these tests varies, but can be estimated by the administrative assistant making the appointment.