How is cryotherapy performed in a case of scleral buckling?

Cryotherapy Technique in Scleral Buckling Surgery

Cryotherapy in scleral buckling is performed transscleral using a cryoprobe applied externally to the sclera overlying the retinal breaks, creating a chorioretinal adhesion through controlled freezing that extends from the ora serrata to completely surround all tears. 1, 2

Surgical Approach and Visualization

The procedure can be performed using two main visualization methods:

• Indirect ophthalmoscopy remains the traditional standard approach, requiring significant expertise to accurately localize retinal breaks and apply treatment 2
• Surgical microscope technique has emerged as an alternative that provides clear visualization of retinal breaks and more controllable application, achieving 92.6% initial reattachment rates 3

Technical Execution

Application Technique

• The cryoprobe is applied externally to the scleral surface overlying the identified retinal breaks 2, 4
• Treatment must extend anteriorly to the ora serrata if tears cannot be completely surrounded, as inadequate anterior extension is a significant risk factor for surgical failure 1
• The anterior border of horseshoe tears requires particular attention, as this area is difficult to visualize and inadequate treatment here commonly leads to failure 1

Timing Considerations

Cryotherapy can be performed either:

• Intraoperatively (traditional approach) - applied during the scleral buckling procedure 4
• Postoperatively (typically 1 month later) - though this requires a second intervention and increases cost 4

The intraoperative approach is generally preferred as it completes treatment in a single session, though postoperative laser photocoagulation offers comparable anatomical success with faster visual recovery and fewer complications like eyelid edema 4

Critical Technical Considerations

Treatment Extent

• All retinal breaks must be completely surrounded by cryotherapy application 1
• The chorioretinal adhesion from cryotherapy is not firm or complete for up to 1 month following treatment, during which continued vitreous traction can pull tears beyond the treated area 1
• This delayed adhesion formation necessitates adequate initial treatment coverage 1

Common Pitfalls to Avoid

• Insufficient anterior extension - failing to extend treatment to the ora serrata when complete surrounding is impossible 1
• Inadequate treatment of horseshoe tear anterior borders - the most common site of treatment failure 1
• Missed retinal breaks - accounting for 22% of redetachment cases in one series 3
• Incomplete sealing of breaks - responsible for 28% of redetachment cases 3

Complications and Outcomes

Expected Complications

• Eyelid edema occurs more frequently with cryotherapy compared to laser photocoagulation 4
• Subretinal fluid blebs may appear 8.7 weeks (mean) after successful reattachment, likely due to choroidal vascular changes from cryotherapy, but resolve spontaneously within one year 5
• Slower visual recovery compared to laser techniques, though final visual acuity at 6 months shows no significant difference 4

Success Rates

• Primary anatomical success rates of 92.6-95% at one week are achievable with proper technique 3, 4
• Final reattachment rates approach 98.8-100% after additional procedures if needed 3, 4
• New break development occurs in 10-16% of patients during long-term follow-up, with pseudophakic patients at higher risk 1

Relationship to Strabismus Complications

While not directly related to cryotherapy technique, scleral buckling procedures can cause multifactorial strabismus through direct muscle trauma, myotoxicity from retrobulbar anesthesia, muscle slippage or disinsertion, superior oblique tendon entanglement, and mass effect from the buckle 6. Approximately 50% of patients with post-buckling diplopia have a torsional component, usually excyclotropia 6.