12.2  Posterior Segment Procedures

12.2.1 Fluorescein Angiography

Y (Why Have the Procedure)

“Fluorescein angiography is an important test to study the retina (or “film”) at the back of your eye. It is used to diagnose certain eye conditions and to guide treatment. It is commonly performed in diabetic retinopathy, age-related macular degeneration and diseases affecting the blood vessels in your eye.”

M (Mechanism, What is the Procedure)

“Fluorescein angiography uses a dye to take special photos of the back of your eye (retina)”.

  • “The procedure is performed in the clinic. A yellow dye is injected into a vein in your arm, the dye then travels via blood vessels to your eye. Its passage through the blood vessels in the retina is recorded with a camera. The flash is bright and because the photographs are quite frequent, you may find that you will temporarily lose vision in your eye. The photographer will instruct you where to look.”

C (Complications)

“This is a commonly performed and generally safe procedure, but as with any medical procedure, complications can occur”:

More Common

  1. All patients notice that their skin, eyes and urine turn yellow. This is from the dye and will resolve completely over 1 - 2 days
  2. Nausea (Approximately 1 in 10)
  3. Vomiting (1 in 100)

Less Common

  1. Urticaria (1 in 1000)
  2. Anaphylaxis (1 in 10000)
  3. Death (1 in 200000)

A (Alternatives)

Optical coherence tomography-Angiography (OCT-A), OCT, indocyanine green angiography (ICG) and fundus autofluorescence may offer complementary information.

Extra Questions

  1. Allergies
  2. Pregnancy (probably safe but best avoided if possible)

NB: Renal failure is not a contraindication to fluorescein angiography.

Confirm that the patient understands. Any questions?

12.2.2 Intravitreal Injection

Y (Why Have the Procedure)

“An intravitreal injection is an injection into the jelly inside the eye called the vitreous. This delivers medication to the retina at the back of the eye. It is a commonly performed procedure used to treat a number of conditions including age-related macular degeneration, diabetic retinopathy, inflammation in the eye and diseases affecting the blood vessels in the retina.”

Neovascular AMD

“There are two forms of macular degeneration: wet and dry. You have the wet form where abnormal blood vessels grow underneath the retina causing bleeding that blurs your vision. We now have drugs that when injected in the vitreous can stop the growth of these vessels and reduce the bleeding. Most patients will notice an improvement in their vision. You are likely to require a number of treatments, initially monthly.”

M (Mechanism, What is the Procedure)

“Medication will be given into your eye as an injection”

  • “This will be performed in a procedure room in the clinic. It takes about 5 minutes. Anaesthetic drops will be put into your eye (and sometimes a local anaesthetic injection) so it doesn’t hurt. Your eye and eyelids will be cleaned with an antiseptic to reduce the risk of infection. Your eyelids will be held open with a special clip. Most patients don’t feel the injection. You may see bubbles or fluid swirling as the medicine is injected. After the injection you’ll be able to go home.
  • “I’ll also give you an information sheet and contact number if you have any concerns”

C (Complications)

Most patients tolerate the injection very well.

Common

  1. Grittiness due to povidone-iodine (resolves on its own)
  2. Subconjunctival haemorrhage (“bloodshot eye”)
  3. Floaters

Less Common

Serious complications occur rarely (<0.1%):

  1. Endophthalmitis 1:3000
  2. Cataract due to lens touch
  3. Retinal tear / detachment
  4. Central retinal vascular occlusion - check vision and retinal vascular perfusion post-injection

Any of these complications can lead to severe permanent loss of vision.

Vision

Astigmatism is common
May need glasses/contact lenses/another operation
Takes time for good vision

Specific Considerations:

A) Anti-VEGF Injections

  1. Risk of thromboembolic events: “There are some concerns that it may increase your risk of stroke. The evidence for this is inconclusive, however if you have a history of stroke or heart attack I would like to discuss this with your physician before going ahead with the treatment.”
  2. Contraindication in pregnancy

B) Intravitreal Steroid Injections

  1. Triamcinolone Acetate: 2/3 develop glaucoma; 1/3 require glaucoma surgery
  2. Dexamethasone intravitreal implant (Ozurdex): 1/3 develop glaucoma; 1% require glaucoma surgery With both options cataract will eventually develop

A (Alternatives)

  1. No treatment: Likely to lead to further vision loss / blindness
  2. Photodynamic therapy
  3. Thermal laser

Confirm that the patient understands. Any questions?

12.2.3 Macular Laser

Y (Why Have the Procedure)

“You have swelling at the back of your eye (“retina”) due to leaking blood vessels from diabetes / vein occlusion. This swelling is causing a reduction in your vision (“wet camera film” analogy)”.

Aims:

  1. Reduce the leak
  2. Maintain your vision (ETDRS: 50% reduction in moderate vision loss, don’t promise that vision will improve)

M (Mechanism, What is the Procedure)

  • “Laser is used to seal off leaking blood vessels at the back of your eye.”
  • “It is performed on a laser “slit-lamp”. You will be given anaesthetic drops and a contact lens is placed on your eye during the procedure. You should not feel pain. You may need more than 1 treatment session (usually 3 months later). Immediately after the laser you won’t see much but your vision will gradually come back over the next few hours.”

C (Complications)

Although macular laser has a good success rate, complications may occur:

  • Central / paracentral scotoma: Inadvertent foveal burn (“may lose central vision but won’t go blind”), scar expansion, foveal lipid dump


Stress close follow-up, need for urgent review if vision declines.

A (Alternatives)

  1. Observation: Higher risk of vision loss
  2. Intravitreal anti-VEGF: First-line treatment in most patients
  3. Intravitreal triamcinolone: Risks of intravitreal injection / cataract / glaucoma

Confirm that the patient understands. Any questions?

12.2.4 Pan-Retinal Photocoagulation (PRP)

Y (Why Have the Procedure)

“You have advanced damage to the back of your eye (“retina”) from diabetes. This has resulted in the growth of abnormal blood vessels in the retina. If left untreated these blood vessels can bleed (reducing your vision) or cause scarring and retinal detachment.”

Aims:

  1. Regress the vessels
  2. Prevent bleeding in the eye (vitreous haemorrhage) or retinal detachment, which can result in severe vision loss

This is the mainstay of treatment for proliferative “severe” diabetic retinopathy and has been demonstrated to reduce the risk of severe vision loss by 50% (Diabetic Retinopathy Study DRS).

M (Mechanism, What is the Procedure)

“Laser targeting the peripheral part of the back of your eye (“retina”) is required to prevent bleeding and preserve your central vision.”

  • It is performed on a laser “slit-lamp”. You will be given anaesthetic drops and a contact lens will be held on your eye. You may feel some discomfort- let me know if it is getting too sore. You will likely need several treatments over a few weeks. Each session takes around 10 minutes. Immediately after the laser you won’t see much but this will gradually come back over the next few hours.”

C (Complications)

“Although PRP has a good success rate, complications may occur:”

Pain / Discomfort

Can have peribulbar anaesthetic if unable to tolerate

↓ Peripheral / Night vision

↓ Night Vision (Nyctalopia)

Loss of Near Vision

Reduced accommodation in pre-presbyopic patients

Vision Loss

Uncommon (worsening of macular oedema, inadvertent foveal burn, CNV)

Stress close follow-up, need for urgent review if develops reduced vision.

A (Alternatives)

  1. Observation: Higher risk of vision loss
  2. Intravitreal anti-VEGF: Temporary effect only. Risks of intravitreal administration.
  3. Cryotherapy of peripheral retina

Confirm that the patient understands. Any questions?

12.2.5 Photodynamic Therapy (PDT)

Y (Why Have the Procedure)

“You have an abnormal blood vessel or vessels in the back of your eye that could result in long term vision loss without treatment. This treatment helps to seal off those abnormal blood vessels.”

PDT can be used for central serous chorioretinopathy (CSC) as well as certain types of wet age-related macular degeneration (polypoidal choroidal vasculopathy).

Aim: Stop further leaking and stabilise vision, may improve vision in some cases.

M (Mechanism, What is the Procedure)

Preparation:

“PDT will make your skin very sensitive to sunlight for 48 hours after the procedure. You should wear long sleeve shirts, pants, feet and hand covering, hat and sunglasses if you need to go outside during this period. This also includes halogen type lights at home.”

You must exclude the following:

  • Liver Failure: Contraindicated (Verteporfin is hepatically excreted)
  • History of Porphyria, SLE: Contraindicated
  • Concurrent use of light sensitising agents (tetracyclines, isotretinoin, sulfonamides, phenothiazines, sulfonylurea hypoglycemic agents, thiazide diuretics and Griseofulvin, etc): Stop if safe to prior to use


PDT consists of 2 parts:

  • “Dilating drops will be given to the eye(s) that require treatment. A needle will be placed in your arm to allow for an injection of dye called Verteporfin. This is given by body surface area dosing and your weight and height will be measured. The doctor will then wait up to 5 minutes before starting the treatment. You place your chin on a chinrest of a machine and must remain still to allow for the focussing of light onto the back of your eye. They will numb your eye with a drop and place a special lens to allow them to see the back of the eye clearly. The treatment will last up to 83 seconds.”

C (Complications)

PDT is a less common form of treatment for retinal conditions. There are very low but significant risks in treatment, though this appears to be reduced when treating CSR given that the treatment is halved.

  1. From Verteporfin
    1. Injection site reaction
    2. Photosensitivity
    3. Anaphylaxis (very rare)
  2. From PDT laser
    1. Choroidal infarction (4%, less with reduced fluence PDT)

A (Alternatives)

Central Serous Chorioretinopathy
  1. Conservative
    1. May improve without treatment, especially if acute CSC
    2. Avoid inciting agents (e.g. steroids)
  2. Laser photocoagulation to focal leaks
  3. Subthreshold micropulse laser
  4. Systemic medications (but poor evidence for their use: Eplenerone found to be ineffective in the VICI trial)
Neovascular Age-related Macular Degeneration
  1. Conservative
    1. Likely to lead to permanent vision loss
  2. Intravitreal injections
    1. See 12.9 Intravitreal Injection

Confirm that the patient understands. Any questions?

12.2.6 Retinal Detachment Repair

Y (Why Have the Procedure)

“Your retina, which is like the film of a camera, has detached. A retinal detachment typically occurs because of a tear in the retina, which allows fluid to migrate underneath the retina, causing the retina to separate from the eye wall. You require an operation to re-attach the retina in an attempt to restore your lost.”

Your visual outcome will depend on the severity of the retinal detachment and whether the centre of the retina (macula) is involved. In some cases, it can take weeks to months before the vision improves.”

M (Mechanism, What is the Procedure)

A retinal detachment can be repaired in multiple ways. The severity of the detachment, location and number of tears, presence of scar tissue and the age of the patient all factor into the choice of surgery.

Most operations are performed under a local anaesthetic in the operating theatre and take between 30-60 minutes.

i. Vitrectomy

“A vitrectomy removes the gel that fills the eye and relieves traction that caused the retina to tear. After the gel is removed, it may be replaced with a gas bubble which floats inside the eye and helps flatten the retina. The gas bubble dissolves on its own over many weeks and is replaced by the eye’s natural fluid. Laser is often used during surgery to fix the retina into place. If there is a large amount of scar tissue is present, silicone oil may be used instead but will need to be removed months later with another operation”

Patients are not allowed to fly with a gas bubble inside the eye.

ii. Scleral Buckle

“A scleral buckle involves the placement of a band around the outside of the eye. It hugs the eye wall towards the retina and helps to seal the tears that caused the retinal detachment. The scleral buckle is left permanently in place.”

Scleral buckles are generally indicated for younger, myopic, phakic patients with inferior retinal breaks.

iii. Pneumatic Retinopexy

Pneumatic retinopexy is a procedure which can repair certain uncomplicated retinal detachments. It is usually done as an outpatient procedure with a local anaesthetic.

“A gas bubble is injected into the middle of the eye and your head is positioned so that the bubble floats to the detached area and presses against the detachment. The retinal tear is sealed using a freezing probe or laser beam. The bubble helps to flatten the retina until a seal forms between the retina and the wall of the eye over a few weeks.”

C (Complications)

The success rate with a single procedure is between 80-90%. It is generally accepted that pneumatic retinopexy has a slightly lower success rate than the other two procedures.

Complications of Vitrectomy Surgery Include:

  1. Failure: Need for additional retinal detachment surgery
  2. Infection
  3. Bleeding inside the eye
  4. Elevated eye pressure with resultant glaucoma
  5. Cataract, which will in time require additional surgery.

Complications of Scleral Buckle Surgery include:

  1. Failure: Need for additional retinal detachment surgery
  2. Infection
  3. Bleeding inside the eye
  4. Elevated eye pressure with resultant glaucoma
  5. Change in power of the eye (myopic shift, astigmatism)
  6. Double vision (diplopia)
  7. Extrusion of the buckle

A (Alternatives)

Deciding between the three procedures is dependent on the severity of the detachment, location and number of tears associated with the detachment, the presence of cataract, scar tissue or bleeding, the age of the patient and the ability of the patient to posture.

If no surgery is performed, the patient will inevitably have permanent vision loss, with disfigurement and shrinkage of the eye possible.

Confirm that the patient understands. Any questions?

          

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