Indications

1. Prophylaxis of selected retinal tears and areas of abnormal vitreoretinal adhesion (e.g., lattice degeneration).

2. Rare cases of progressive retinoschisis.

3. Treatment of selected retinal tumors and vascular malformations (e.g., Coats disease).

4. Peripheral panretinal cryotherapy to induce regression of neovascularization in:

a. Selected cases of neovascular glaucoma.

b. Proliferative retinopathies refractory to panretinal photocoagulation (PRP) or in eyes in which PRP is not possible (e.g., media opacities).

Preoperative Procedure

1. Complete retinal evaluation: Identify and draw all retinal breaks or other areas of pathology (e.g., lattice degeneration, retinal telangiectasia).

2. Dilate pupil (e.g., cyclopentolate 1% + phenylephrine 2.5%).

Instrumentation

Indirect ophthalmoscope

Scleral depressor

Cryosurgical unit with retinal cryoprobe

Tuberculin syringe and 5/8-inch 30 gauge needle

2% lidocaine without epinephrine

Lid speculum (preferably wire type)

Operative Procedure

1. Treatment of retinal breaks

a. Localize and draw all retinal breaks (indirect ophthalmoscope, scleral depressor).

b. Open gas valve and test cryoprobe (desired temperature should be –60 to –80°C; usually requires nitrogen gas tank pressure > 600 psi).

c. Apply anesthesia.

  i. Subconjunctival lidocaine 2% without epinephrine to quadrants that will be treated.

 ii. Retrobulbar anesthesia (± lid block) may be used in patients receiving extensive treatment (e.g., panretinal cryopexy) but usually is not necessary if extensive subconjunctival anesthesia is used.

Figure 65.1