Supplies Needed

1. Ophthalmic proparacaine or tetracaine.

2. 5% povidone-iodine.

3. Eyelid speculum.

4. 1% or 2% lidocaine without epinephrine.

5. Alcohol wipes.

6. Cotton tip applicators as needed.

7. 1- or 3-mL syringe with an 18-gauge needle to fill a syringe with lidocaine and a 30-gauge needle (1/2- to 5/8-inch length) for subconjunctival lidocaine injection.

8. 25- or 27-gauge needle (1/2- to 5/8-inch length) on a 3-mL syringe for vitreous tap. If the patient has had a pars plana vitrectomy, a 30-gauge needle may be used.

9. 30-gauge needle (1/2- to 5/8-inch length) on a 1-mL syringe for anterior chamber tap.

10. 1-mL syringe or caliper to mark the injection site.

11. 30-gauge needle (1/2- to 5/8-inch length) on a 1-mL syringe with indicated intravitreal injection(s).

12. Specimen cap.

Procedure Steps (See Video: Intravitreal Tap and Inject)

1. Anesthetize the eye with topical proparacaine or tetracaine.

2. Apply 1 to 2 drops of 5% povidone-iodine.

3. Insert speculum.

   1. Tips: A wire or plate speculum may be used. Plate speculum can provide more comfort if the eye is painful.

4. Using a 1-mL syringe with a 30-gauge needle, inject ∼0.5 mL of lidocaine subconjunctivally. (We suggest waiting at least 5 minutes after the subconjunctival lidocaine before proceeding with the tap and inject. Longer may be better in very inflamed eyes. The eyelid speculum can be removed while waiting and then reinserted before the subsequent steps.) The injection should be placed in the area of the anticipated vitreous tap and injection.

   1. Tips:

      • To optimize ocular anesthesia, wait for at least 5 minutes after lidocaine injection. 

      • Subconjunctival lidocaine may not yield complete ocular anesthesia with the tap, especially in very inflamed eyes. Both the physician and patient should be prepared for possible patient movement if there is any discomfort during the procedure.

5. Mark the injection site by pressing the tip of a 1-mL syringe on the surface of the eye to create an imprint. Place one edge of the syringe tip at the inferotemporal limbus. The outer edge of the tip will mark 4 mm from the limbus.

   1. Tips:

      • The entry point of injection should be 4 mm from the limbus in phakic patients and 3.5 mm in pseudophakic patients.

      • Alternatively, a caliper may be used to measure the exact distance.

6. Apply another 1 to 2 drops of 5% povidone-iodine.

7. Using a 25- or 27-gauge needle on a 3-mL syringe, enter the eye at your marked site, aiming posteriorly toward the optic nerve.

   1. Tips:

      • In phakic patients, it is crucial to remain perpendicular to the entry plane as to avoid hitting the lens.

8. Carefully pull back on the plunger to create a vacuum. The sample volume should be between 0.1 and 0.3 mL.

   1. Tips:

      • Sample may not immediately be obtained. Several techniques can be used to optimize yield:

        1. Aspirate in one location first. If there is no return of fluid, release the suction and slowly pivot the needle to a slightly different location and then try to aspirate again.

           Or

        2. Carefully move the needle slowly in and out after insertion into the vitreous cavity to find a pocket of liquid vitreous.

9. If the vitreous tap is unsuccessful, convert to an anterior chamber tap. Using a 30-gauge needle on a 1-mL syringe, insert the needle and bevel up, through the clear cornea in the inferotemporal quadrant, over the iris. Gently pull back on the plunger to obtain a 0.1- to 0.2-mL sample.

   1. Tips:

      • If the patient is phakic, it is crucial to keep the needle in the horizontal plane over the iris to avoid hitting the lens capsule. If the patient is pseudophakic, you may enter at the limbus and aim the needle more centrally while still taking care to avoid contact with the iris, intraocular lens, or corneal endothelium. A sterile cotton swab may be used to stabilize the globe by placing the tip of the swab on the nasal side of the globe to provide countertraction.

10. Place specimen cap on the syringe.

11. Prepare for intravitreal injection by applying 1 to 2 drops of 5% povidone-iodine to the surface of the eye.

12. Inject intravitreal agent(s) at the previous injection site using a 30-gauge needle on a 1-mL syringe. See Video: Intravitreal Injection.

13. Remove speculum.