Test for Retinal Detachment

The retina is a light-sensitive membrane that lines the inside back wall of the eye. Retinal detachment is when the retina is separated from its supporting layers called the choroid--a thin layer of blood vessels that supplies the retina with oxygen and nutrients. When this occurs, the retina is deprived of oxygen, which if not treated immediately can lead to permanent vision loss.

Identification

• Retinal detachment can occur on its own without any underlying causes, but it can also be due to a tear or a hole in the retina, trauma, an inflammatory disorder or uncontrolled diabetes. An individual who at risk for retinal detachment might experience the following symptoms: bright flashes of light in their peripheral vision, floaters, a shadow or blind spot in their field of vision, visual distortions or sudden or gradual blurred vision. Retinal detachment is a serious medical condition, which requires immediate diagnosis and treatment. Tests will be conducted to check the retina and pupil response and your ability to see colors properly. Some tests include electroretinogram, ophthalmoscopy, refraction test and fluorescein angiography.

Electroretinogram

• An electroretinogram (ERG) is an eye test used to detect abnormal function of the retina. During this exam, a patient will have her eyes dilated and then anesthetic drops are applied to numb the eye. A speculum is used to prop open the eyelids and an electrode is placed on the patient's cornea. The electrode, which is similar to a contact lens, measures the electrical activity of rods and cones. Rods and cones are cells that sense light in the retina. Using light as a stimulus, two types of waves called A waves and B waves are recorded and analyzed. The test takes about an hour to complete and is virtually painless.

Ophthalmoscopy

• Ophthalmoscopy is an examination of the back part of the eyeball called the fundus. An ophthalmologist uses an instrument with a bright light and powerful lens called an ophthalmoscope to view the fundus in three dimensions and in great detail. This instrument allows the doctor to detect a hole, tear or detachment of the retina. There are three types of ophthalmoscopy: direct ophthalmoscopy, indirect ophthalmoscopy and slit-lamp ophthalmoscopy. Direct ophthalmoscopy is the standard test that is commonly performed during routine eye exams. In a darkened room, a doctor will check the back of a patient's eye by shining a beam of light through the pupil. Indirect ophthalmoscopy involves pressure being applied to the eye by a small blunt tool and the examiner will use a variation of an ophthalmoscope that is worn on the head like a miner's light. In a slit-lamp ophthalmoscopy exam, a low-power microscope combined with a high-intensity light source that can be focused to shine in a thin beam is used to examine the eye. Unlike the two former exams, a patient may have his eyes dilated during slit-lamp ophthalmoscopy. Each of these exams lasts approximately 15 minutes and can cause some minor discomfort.

Refraction Test

• A refraction test is an eye exam that determines whether a person's vision is normal. A patient is seated in a chair that has a special device called a refractor attached to it. A refractor contains several lenses or various strengths. The doctor will ask the patient to focus on a chart that is about 20 feet away and asked if it appears more or less clear through various lenses that are moved into view. A normal value for perfect vision is 20/20. Perfect vision means a person has the ability to read 3/8 inch letters at 20 feet. Poor or blurred vision can be an indicator of eye disease. The exam is painless and its length is determined on a case-by-case basis.

Fluorescein angiography

• Fluorescein angiography is a test used to determine if there is proper circulation in the blood vessels of the retina. Dilating drops are placed in a patient's eyes to enlarge the pupils so the doctor can get a better view of the internal structures of the eye. It will take 20 to 30 minutes for the drops to take effect and when they do a variety of instruments and light sources will be used to look inside the eyes. Several pictures will be taken before the doctor injects a special dye called fluorescein into the patient's vein, usually by the elbow. The dye is photographed by a special camera as it moves through the blood vessels in the back of the eye. Doctors are looking to see if vessels appear to be a normal size and if any blockages or leakages exist. Mild nausea and warming sensations may briefly be experienced after the injection. Patients have reported feeling moderate pain when the needle is inserted and a throbbing sensation at the injection site later on. Depending on the strength of the dilating drops used, side effects, such as difficulty focusing on objects up close, can last for several hours after the completion of the exam.