Mechanism of Cryotherapy in Scleral Buckling
Cryotherapy in scleral buckling creates a controlled chorioretinal adhesion through transscleral freezing that permanently seals retinal breaks, preventing subretinal fluid progression and halting retinal detachment. 1
Primary Mechanism of Action
The fundamental goal is to create a firm chorioretinal adhesion in the attached retina immediately adjacent to and surrounding the retinal tear, which halts the progression of subretinal fluid from detaching the neurosensory retina. 1
Technical Execution
Cryotherapy is applied transscleral using a cryoprobe placed externally on the sclera overlying the retinal breaks, creating controlled freezing that induces inflammation and subsequent scarring between the choroid and retina. 2
The treatment must completely surround all retinal breaks and extend anteriorly to the ora serrata if tears cannot be fully encircled, as this is critical for preventing surgical failure. 2
The freeze-thaw cycle causes controlled tissue damage that triggers an inflammatory response, leading to fibroblast proliferation and collagen deposition that permanently bonds the neurosensory retina to the underlying retinal pigment epithelium and choroid. 3
Critical Timing Considerations
A major caveat is that the chorioretinal adhesion from cryotherapy is not firm or complete for up to 1 month following treatment. 4, 2 During this vulnerable period:
- Continued vitreous traction can pull tears beyond the treated area 4
- This delayed adhesion formation necessitates adequate initial treatment coverage with proper margins 2
- The scleral buckle provides immediate mechanical support during this healing period by indenting the scleral wall to relieve vitreoretinal traction 3
Common Technical Pitfalls
The anterior border of horseshoe tears is the most common site of treatment failure because this area is difficult to visualize and inadequate treatment here leads to persistent or recurrent detachment. 4, 2
Insufficient anterior extension represents another critical failure point—treatment must extend to the ora serrata when complete surrounding of tears is impossible. 4, 2
Inadequate treatment of any portion of the retinal break is the most common cause of failure in treating horseshoe tears. 1
Clinical Outcomes
Treatment by prompt creation of chorioretinal adhesion reduces the risk of retinal detachment to less than 5% in symptomatic tears. 1
New break development occurs in 10-16% of patients during long-term follow-up, with pseudophakic patients at higher risk, emphasizing that cryotherapy addresses existing breaks but does not prevent future pathology. 4, 2
Both cryotherapy and laser photocoagulation achieve similar anatomical success rates (93-100% reattachment), though cryotherapy causes more eyelid edema and slower initial visual recovery. 5
Comparison with Alternative Techniques
The American Academy of Ophthalmology guidelines indicate low to very low certainty evidence showing little or no difference between pars plana vitrectomy and scleral buckling in anatomical and visual acuity outcomes, confirming that scleral buckling with cryotherapy remains a comparable and valid surgical approach. 1, 4