Regular eye examinations are an important part of preventative health care. While blurred vision or irritated eyes are often the reason for patients coming in to see their eye doctor, many eye and vision problems have no specific signs or symptoms. For this reason, many people are unaware that they even have a problem. In order to prevent vision loss, as well as maintain good vision and eye health, regular eye examinations are necessary for early diagnosis and treatment.
There are a series of tests that every comprehensive exam should include. Below is a listing of the tests that may be performed at Compton Eye Associates. Based on the patients individual findings and symptoms, there may be other tests added to the list.
An accurate patient history helps to summarize the symptoms the patient is experiencing. Key factors may include finding out when the symptoms began, how often they occur, how long they last and where the symptoms are located. Other key pieces of information to be collected include the presence of any general health problems and medications taken. It is also important to collect any previous eye or health conditions that are present in family members.
Visual acuity measurements allow the doctor to quantify how the patient is seeing. Reading an eye chart helps the doctor measure a patients visual acuity. As part of the testing, the patient will be asked to read letters (or other targets) on distance and near reading charts.
Visual acuity is written as a fraction such as 20/30. The number on the top indicates how far the patient was from the target (usually 20 feet). The number on the bottom indicates the distance that a person with normal vision can see the same line. For example, if your vision is 20/50 that means the line you correctly read at 20 feet can be read by a person with normal vision from 50 feet away.
Entrance exams take a closer look a different aspects of a patients visual function and eye health. These tests assess color vision, depth perception, eye muscle movements, side vision, and the way the pupils respond to light.
Keratometry measures the curvature of the cornea, the clear outer surface of the eye. This test is extremely useful when assessing a patients astigmatism. This finding is particularly important in determining the proper fit for contact lenses.
A refraction is done to determine the appropriate lens power needed for a patient to see better. Using an instrument called a phoropter, the doctor places different lenses in front of the eye. The doctor then uses various techniques to figure out which lenses allow for the clearest vision. This is the exam that reveals Myopia, Hyperopia, Astigmatism and Presbyopia. The test can be performed with and without eye drops.
Eye Focusing and Eye Teaming
Our eyes have a built in focusing system which adjusts the power of the lens in our eyes to see clearly at all distances. Understanding how the two eyes focus and work together as a team is very important. This is done through assessment of accommodation, ocular motility and binocular vision.
Tonometry measures eye pressure. Normal eye pressures range from 10 to 21 millimeters of mercury (mm Hg) . If a patient has elevated pressure, they are at an increased risk of glaucoma. The most accurate measure for pressure comes from a Goldmann Tonometer. This is the method that uses eye drops and an instrument called a slit-lamp. Other methods of measuring pressure include handheld devices and a non-contact (or air puff) tonometer.
Anterior and Posterior Segment Examination
Using brignt light and magnification, the anterior segment evaluation includes an examination of the cornea, eyelids, conjunctiva and surrounding eye tissue. The posterior segment evaluation also uses magnification to evaluate the lens, vitreous and retina. This should be done through a dilated pupil to provide a better view of the internal structures.