Vitrectomy
A vitrectomy may be performed to clear blood and debris from the eye, to remove scar tissue, or to alleviate traction on the retina. The Vitrectomy actually removes vitreous gel from the eye through a small incision using a laser. Vitrectomy allows the retina to flatten. Depending on the severity of the diabetic retinopathy, gas or air might be placed in the eye to replace the vitreous fluid that was removed. This gas or air helps smooth out the retina and prevent retinal detachment.
Retinal Detachment
Flash and Floaters The middle of our eye is filled with a clear gel called vitreous (vi-tree-us) that is attached to the retina. Sometimes tiny clumps of gel or cells inside the vitreous will cast shadows on the retina, and you may sometimes see small dots, specks, strings or clouds moving in your field of vision. These are called floaters. You can often see them when looking at a plain, light background, like a blank wall or blue sky.
As we get older, the vitreous may shrink and pull on the retina. When this happens, you may notice what look like flashing lights, lightning streaks or the sensation of seeing “stars.” These are called flashes.
Usually, the vitreous moves away from the retina without causing problems. But sometimes the vitreous pulls hard enough to tear the retina in one or more places. Fluid may pass through a retinal tear, lifting the retina off the back of the eye — much as wallpaper can peel off a wall. When the retina is pulled away from the back of the eye like this, it is called a retinal detachment.
The retina does not work when it is detached and vision becomes blurry. A retinal detachment is a very serious problem that almost always causes blindness unless it is treated with retina detachment surgery.
Laser Retinopexy
Laser Retinopexy is done for treatment of retinal tears and retinal holes. The laser is used to surround these retinal defects and secures the area. This helps significantly to decrease the chances of a retinal detachment secondary to tear formation. Your Orange County Retina specialist treats retinal tears with a laser by placing several laser spots around the existing hole. The laser spots create scar tissue around the hole helping to keep the retina in place.
Your eye will be dilated for the procedure. A numbing drop is applied. Depending on the size of the tear, your treatment will take 5 to 15 minutes. After your procedure, a mild discomfort may be noticeable but easily treated with ibuprofen.
It is very important to report any of the following symptoms immediately:
- increase in flashes or floaters
- pain which is not relieved by ibuprofen
- decrease in vision
- feeling like a dark curtain is coming across your vision
Floaters Example
ROP
Retinopathy Of Prematurity or ROP is a potentially blinding eye disorder that primarily affects premature infants that are born before 31 weeks of gestation. The smaller a baby is at birth, the more likely that baby is to develop ROP. This disorder typically develops in both eyes and is one of the most common causes of vision problems for children and can lead to enduring vision damage and blindness.
What are the causes of ROP?
Disordered retinal blood vessels or Irregular blood vessels develop throughout the retina. These abnormal blood vessels are delicate and can leak, damaging the retina and drawing it out of normal position. This causes a retinal detachment. Retinal detachment is the main cause of visual impairment and blindness in ROP.
Several intricate factors may be responsible for the development of ROP. The eye starts to develop early in pregnancy, (about 15-16 weeks). This is when the blood vessels of the retina begin to form at the optic nerve in the back of the eye. The blood vessels grow slowly toward the edges of the developing retina, supplying oxygen and nutrients. During the final 12 weeks of a pregnancy, the eye develops quickly. When a baby is born full-term, the retinal blood vessel development is mostly complete. But if a baby is born prematurely, in advance of these blood vessels having reached the edges of the retina, normal progression may stop. The borders of the retina may not get enough oxygen and nutrients. These new blood vessels are fragile and weak and can bleed, leading to retinal scarring. When these scars contract, they pull on the retina, causing it to detach from the back of the eye.
What are the Risk factors for ROP?
- Low birth weight
- Differing types of infections
- Cardiac defects
- High exposure to Oxygen
What are treatment options for ROP?
Some cases of ROP are mild and correct themselves, but others require surgery to prevent vision loss or blindness. Surgery involves using a laser or other means to stop the growth of the abnormal blood vessels, making sure they don’t pull on the retina further damaging vision. There are options that Orange County Retina specialist utilize when treating ROP that all focus on the repairing retinal health.
Retinal Testing
Physiology Lab Testing
The retinal-testing lab at Orange County Retina offers several ways to analyze and diagnose retinal issues that cannot otherwise be made through traditional observation. These tests are broken down into two distinct categories; Psychophysical and Electrophysiologic. Both types of testing require interpretation. The electrophysiologic tests are completely objective and cannot be falsified. While the psychophysical tests are scored objectively, they are measuring a patient’s subjective response.
Psychophysical Testing
RAM – Retinal Acuity Meter: This test requires that sharp, formed images (usually Snellen letters) reach the macula, otherwise the test report may be falsely negative. It is useful in assessing macular function in eyes that may have corneal haze, cataracts, a clouded posterior capsule, or vitreous haze. This test is extremely helpful when planning cataract, corneal transplant, and posterior vitrectomy surgery or other opacities in front of the macula
PAM – Potential Acuity Meter: This is similar to the RAM with somewhat different letter types, contrast, and optics.
BLE – Blue Light Entoptoscopy: Approximately 90% of persons are able to see the flow of white blood cells passing through their macular capillaries. A bright blue light of 430 nm is projected through the patient’s media toward the macula. The light is differentially absorbed by the white blood cells, which cast shadow and are seen as tiny dots flowing through the macular capillaries. As with the above two tests this test is also scored objectively scored and correlates well with macular acuity. The three tests above are tests of macular potential. The BLE test is best able to penetrate media opacities for objective scoring. All three of the above tests require a clinical understanding of the type and density of the media opacities to reduce or eliminate a false negative interpretation of macular potential. We perform the three above tests as a battery, and also consider other testing (ERG, VER) for an accurate assessment report.
Contrast Sensitivity (CS)– Contrast sensitivity: Refers to the ability of the visual system to distinguish between an object and its background. It is important to note that blurred vision is not the same as poor contrast sensitivity. A contrast sensitivity test, checks for the ability to differentiate between light and dark (contrast). This ability, is as much an important sense as 20/20, allowing us to be able to carry out everyday tasks safely. The tests provide useful independent information in relation to a patient’s visual function which is often not be observed through normal visual acuity testing. Measuring contrast sensitivity is an important indicator in quality of life functions i.e., driving and mobility. It may also serve as early detection of AMD, diabetic retinopathy and optic neuritis.
MAIA – Macular Integrity Assessment: This is a variant of a visual field test in which very small targets of variable contrast are projected on the macular geography. The test gives a comprehensive topographical picture of the central portion of the island of Traquair, and, thus, gives a representation of the most important portion of the visual field. This test of macular sensitivity allows for comprehensive macular disease management. This is a non-mydriatic procedure and utilizes a normative database for statistical analysis. It is extremely useful for monitoring pathological changes of the macula over a period of time.
Color sensitivity: There are three tests that allow for the determination or extent of a patients “color blindness”. Perception of color requires macular cone function, neuroretinal integration, optic nerve function, and occipital lobe function. Each eye is tested separately. The Ishihara test is a good screening test. If abnormal, or if highly defined color measurements are necessary, the Farnsworth D-15 and FM-100 give more specific information.
D-15: This test is more expansive than the Ishihara test, and yields a specific color axis that helps determine if the abnormality is retinal or neural
FM-100: This fine hue discrimination is scored in eye each using 88 color chips. It provides quantitative information regarding the exact abnormality.
Electrophysiologic Testing
These analyses are wholly objective in nature, and electrophysiologic data cannot be falsified. However, a report helpful to the clinician integrates the psychophysical testing along with the electrophysiological testing. Also, when clinical information is available the interpretive reports attempt to more deeply answer certain questions that help the clinician reach appropriate conclusions. In general, the results cannot be falsified.
ERG or Electroretinography–ERG, is an eye test used to detect irregular or uncharacteristic function of the retina. During this test, your Orange County Retina specialist examines the light-sensitive cells of the eye, the rods and cones, and their connecting ganglion cells in the retina. An electrode is placed on the cornea to measure the electrical responses to light of the cells (the rods and cones) that sense light in the retina at the back of the eye.
Orange County Retina patients assume a relaxed position, the eyes are dilated and then administered anesthetic drops, causing them to become numb. The eyelids are then propped open, and an electrode is gently placed on each eye with a device comparable to a contact lens. An additional electrode is placed on the skin to provide a ground for the very faint electric indicators produced by the retina.
There are three individual tests:
Light adapted – reflects the activity of the cone system
Dark adapted – reflects the activity of the rod system
Flicker Fusion Frequency – reflects the activity of the cone system when stimulated by rapid light pulses; may be affected by certain diseases (thyroid).
Mf-ERG Multi-focal ERG – This is a macular test that graphs multiple small segments of macular cone function. This test is often done after morphologic fundus changes have been recorded with fluorescein angiography. It is useful in assessing certain toxicities (ex: hydroxychloroquine), macular edema, macular ischemia, and overall macular function in determining etiology of visual loss.
EOG – Electro-oculogram: This is a test of the electrical “standing potential” of the eye. This “long-wave” potential is recorded after both light and dark adaptation, and the ratio of light-to-dark is a measure of the health of the entire retinal unit and supporting structures including the choroid, retinal pigment epithelium, photoreceptors, and entire neurosensory retina. (Disease example: Bests disease)
VER – Visually Evoked Response: Also known as the VECP or visually evoked cortical potential. The retina is stimulated and the microvolt response is recorded (by computer averaging) at the occiput. Both magnitude and time values are important for interpretation, and both tests are heavily influenced by the cone system.
Flash VER – The flash VER utilizes a bright flash of light to stimulate the retina. The flash VER cannot be falsified.
Pattern VER – an alternating black-and-white checkerboard pattern is projected through (clear) media.
