Retinal Detachment
Author: Allen C. Ho, M.D.
1. Definition
Retinal detachment is a separation of the retina (the retina is the thin layer of tissue that retains the vision cells in the back of the eye; the retina is similar to film inside a camera; the macula is the central focus point of the retina that allows someone to see fine details such as reading a book) from the underlying layer. This can lead to loss of peripheral and possibly central vision, depending on the extent of the retinal detachment.
2. Causes and Associations
There are three mechanisms of retinal detachment.
A. Rhegmatogenous retinal detachment is caused by a break, tear or hole in the retina, allowing fluid from the center of the eye, or the vitreous cavity, to seep behind the retina and detach it. Rhegma is Greek for rent or break. Rhegmatogenous retinal detachment is the most common type or retinal detachment. Causes include trauma, separation of the vitreous (the jelly inside the eye that shrinks with age) from the retina, or prior intraocular surgery (e.g., cataract surgery). Nearsightedness is a risk factor for retinal tear and subsequent detachment.
B. Tractional retinal detachment is caused by the pulling of membranes tethered to the retina. These membranous bands can be caused by diabetes mellitus, sickle cell disease, retinopathy of prematurity, or inflammatory conditions.
C. Exudative retinal detachment is caused by fluid, or exudate, leaking from blood vessels underneath the retina. Causes include high blood pressure, vasculitis (inflammation of blood vessels), and tumors in the eye.
3. Symptoms
Patients with rhegmatogenous retinal detachments often present with a shower of floaters (black dots or cobwebs in their vision), flashing lights, and a shadow, curtain, or cloud progressing from their peripheral vision. Patients with tractional retinal detachment may have flashing lights or a shadow over their vision, or they may have no symptoms. Patients with exudative retinal detachment have an area or darkness in their vision, which may shift with head position.
4. Examination
Complete and comprehensive ophthalmic examination is important in the assessment of retinal detachment. Patients will receive vision testing, drops to dilate pupils, and a complete examination of the front and back of the eye. Pupillary dilation may create blurring, and therefore, it is often best if a driver accompanies the patient, although it is not absolutely required. When examining the retina, the ophthalmologist may depress the eye with a cotton tip applicator or other blunt instrument in order to view the entire retina.
4a. Testing
Patients with retinal detachment are largely diagnosed by clinical examination.
Patients may undergo fundus photography to document the extent of retinal detachment. This procedure is of little risk to the patient.
OCT imaging (OCT imaging is a non-invasive optical coherence tomogram examination of the retina; an OCT uses low energy laser to scan the retina and determine whether there is fluid under the retina) can help assess the status of retina and determine if there is a low lying retinal detachment.
4b. What the Doctor Sees
In rhegmatogenous retinal detachment, the ophthalmologist will see one or more breaks in the retina with underlying fluid. This can be accompanied by a vitreous hemorrhage, or bleeding into the central jelly of the eye.
In tractional retinal detachment, there are membranous bands tethered to the retina causing a detachment. The pulling of these bands can lead to a retinal tear, owing to a combined rhegmatogenous and tractional retinal detachment.
In exudative retinal detachment, there is fluid under the retina in the absence of a retinal tear or a tethered band.
5. Prognosis
Retinal detachments were uniformly blinding until the first retinal detachment surgery was performed in the 1920’s. Surgical techniques have evolved since then, allowing good vision for many people with retinal detachment.
Retinal detachments can affect the peripheral and/or the central (i.e., macula) retina. Patients with peripheral retinal detachments can maintain excellent vision if the detachment is successfully repaired and it does not progress to involve the central retina. Patients with central, or macula-involving, retinal detachment can have decent but diminished vision if successfully repaired. Long standing retinal detachments tend to have a poor visual prognosis.
6. Prevention and Treatment
It is important to seek immediate ophthalmic care if one experiences symptoms of a retinal detachment, namely floaters, flashes, or a curtain over one’s vision. If the examining ophthalmologist discovers a retinal break or tear, he or she may refer you to a vitreoretinal surgeon. It may be possible to treat the tear with laser, known as retinopexy, or with a freezing treatment, known as cyrotherapy, to tack down the surrounding retina and prevent a retinal detachment.
There are several modalities to treat a retinal detachment, dependant on the type, location, and size of the detachment.
Pneumatic retinopexy is an office procedure whereby a vitreoretinal specialist injects gas into the eye. This gas bubble helps block or tamponade a retinal tear, allowing the retinal pigment epithelium to pump out the subretinal fluid. Pneumatic retinopexy is coupled with either cryotherapy or laser retinopexy to tack down the retina surrounding the tear. When there is gas in the eye, patients must maintain appropriate head positioning to ensure the gas bubble abuts the retina tear. Also, patients with gas in their eye will be sensitive to significant changes in atmospheric pressure. They should not fly in a plane, mountain climb, or scuba dive until the gas bubble has resorbed.
A scleral buckle is a silicone band that surrounds and indents the eye to re-approximate the retinal detachment. It is coupled with cryotherapy or laser retinopexy. Patients will develop a cataract and become more nearsighted after this procedure.
Patients with complicated tractional or exudative retinal detachments may require intraocular surgery (i.e., vitrectomy) removing the vitreous, or jelly, from the eye. This surgery allows removal of tractional bands tethered to the retinal. The surgeon may leave a gas bubble or silicone oil in the eye after vitrectomy to help reattach the retina.
Exudative retinal detachments are treated by addressing the underlying cause.
Flashes and Floaters
1. Definition
The small specks or “bugs” that many people see moving in their field of vision are called floaters. They are frequently visible when looking at a plain background such as a blank wall or blue sky. Floaters were described long ago, in Roman times, as flying flies (“muscae volitantes”).
Flashes of light are often described as a camera flash, lightening, or firework going off in the eye.
2. Causes and Associations
Floaters are small clumps of cells or tissue that form in the vitreous gel, the clear jelly-like fluid that fills the inside cavity of the eye. Although they appear to be in front of the eye, they are actually floating in the fluid inside the eye and are seen as shadows cast on the retina (the light-sensing inner layer of the eye). Uncommonly, floaters result from inflammation within the eye or from crystal-like deposits which form in the vitreous gel. Posterior vitreous detachments occur because the vitreous liquefies with age and separates from the retina. Approximately two-thirds of 70-year-olds will have a posterior vitreous detachment.
Flashes are cause by stimulation of the retina, often by tugging by the vitreous gel. Flashes are also caused by a detaching retina.
Flashes and floaters are usually not serious, but there are exceptions. As the vitreous gel pulls away, the retina may be torn, sometimes causing a small amount of bleeding in the eye which may appear as a group of new floaters. Tears in the retina are potentially serious because they can lead to retinal detachment and visual loss.
Without examination by an ophthalmologist, there is no way for a person to determine whether floaters are serious. Any sudden onset of many new floaters flashes of light should be evaluated promptly by your ophthalmologist.
3. Symptoms
Patients with posterior vitreous detachment often present with a large floater and transient flashes of lights. Patient with retinal detachments often present with a shower of floaters (black dots or cobwebs in their vision), flashing lights, and a shadow, curtain, or cloud progressing from their peripheral vision.
4. Examination
Complete and comprehensive ophthalmic examination is important in the assessment of flashes and floaters. Patients will receive vision testing, drops to dilate pupils, and a complete examination of the front and back of the eye. Pupillary dilation may create blurring, and therefore, it is often best if a driver accompanies the patient, although it is not absolutely required. When examining the retina, the ophthalmologist may depress the eye with a cotton tip applicator or other blunt instrument in order to view the entire retina to rule out tears.
4a. Testing
Patients with flashes and floaters are largely diagnosed by clinical examination.
4b. What the Doctor Sees
In posterior vitreous detachment, the ophthalmologist will see a clump floating in the vitreous. Approximately 10% of posterior vitreous detachments are associated with retinal tears or breaks. Sometimes a posterior vitreous detachment plucks a blood vessel and causes a vitreous hemorrhage, or bleeding into the central jelly of the eye, which has a greater association with retinal tears.
In retinal detachment, the ophthalmologist will see one or more breaks in the retina with underlying fluid. This can be accompanied by a vitreous hemorrhage.
5. Prognosis
In the absence of a retinal tear, vitreous clumps and posterior vitreous detachments are relatively benign. Floaters may sometimes interfere with clear vision, often when reading, and can be quite annoying. If a floater appears directly in your line of vision, the best thing to do is move your eye around, which will cause the inside fluid to swirl and allow the floater to move out of the way. We are most accustomed to moving our eyes back and forth, but looking up and down will cause different currents within the eye and may be more effective in getting the floaters out of the way. Often, floaters will break up or shift to the side with time, making them less noticeable or bothersome.
6. Prevention and Treatment
There is no way to prevent floaters due to vitreous clumps or posterior vitreous detachments. If associated with a retinal tear, a subsequent retinal detachment may be prevented by laser or freezing (i.e., cyrotherapy) treatment.
