In 1988, the Cryotherapy for ROP study demonstrated that ablation of the avascular anterior retina in ROP eyes with threshold disease reduced by approximately half the incidence of unfavorable outcomes (eg, macular dragging, retinal detachment, and retrolental cicatrix formation). Treatment reduced these sequelae from 47% to 25% at 1 year follow-up, and visual results were shown to parallel anatomical results. At 10 years, eyes that received cryotherapy were still much less likely to be blind than untreated control eyes.
The ETROP trial randomly assigned 1 eye of infants with bilateral, high-risk, prethreshold ROP to receive early ablation of the avascular retina and the fellow eye to receive conventional management according to Cryotherapy for ROP study methods. High risk was determined using a computational model based on the natural history cohort of the Cryotherapy for ROP study; this model used demographic characteristics of the infants and clinical features of ROP to classify eyes with prethreshold ROP as either high risk or low risk. In infants with high-risk prethreshold ROP, earlier treatment was associated with a reduction in unfavorable visual acuity outcomes (from 19.5% to 14.5%; P = .01) and a reduction in unfavorable structural outcomes (from 15.6% to 9.1%; P < .001) at 9 months. The study determined that the clinical categorization of prethreshold eyes into type 1 or type 2 ROP achieved very similar results to the computational model for risk assessment to prethreshold eyes.
Any eyes meeting the criteria for type 1 ROP should be considered for peripheral retinal ablative treatment, whereas type 2 ROP eyes can be monitored in short intervals; laser ablative treatment can be considered if type 2 ROP eyes progress to type 1 ROP or threshold ROP. The authors of the ETROP study pointed out that the prethreshold treatment algorithm did not account for all other known risk factors for ROP progression, such as systemic disease, and that clinical judgment is still required for optimal disease management.
Early Treatment for Retinopathy of Prematurity Cooperative Group. Revised indications for the treatment of retinopathy of prematurity: results of the Early Treatment for Retinopathy of Prematurity Randomized Trial. Arch Ophthalmol. 2003;121(12):1684–1694.
Shulman JP, Hobbs R, Hartnett ME. Retinopathy of prematurity: evolving concepts in diagnosis and management. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2015, module 1.
Laser and Cryoablation Surgery
Ablation treatment of threshold or prethreshold type 1 ROP should be performed with laser surgery rather than cryoablation surgery whenever possible, because laser surgery is associated with less treatment-related morbidity. Treatment should be administered within 72 hours of determining its need and applied using the indirect ophthalmoscope in a confluent or subconfluent scatter pattern to the avascular retina anterior to the ridge (Fig 8-8). In the horizontal meridians, laser treatment should be applied in a lighter pattern to avoid damage to the long ciliary vessels and nerves; damage to these structures can lead to severe anterior segment ischemia. Although the use of retinal cryoablation surgery is now rare (in the United States), the technique may still have a role in the treatment of eyes with media opacities or persistent tunica vasculosa lentis, or when a laser is not available. Because respiratory or cardiorespiratory arrest can occur in up to 5% of treated infants, treatment should be performed in conjunction with pediatric consultation and with systemic monitoring. Use of systemic analgesia is also advisable to minimize stress and risk to the infant. Some neonatologists prefer that infants undergo treatment with general anesthesia in an operating room.
Brown GC, Tasman WS, Naidoff M, Schaffer DB, Quinn G, Bhutani VK. Systemic complications associated with retinal cryoablation for retinopathy of prematurity. Ophthalmology. 1990;97(7):855–858.
Connolly BP, McNamara JA, Sharma S, Regillo CD, Tasman W. A comparison of laser photocoagulation with trans-scleral cryotherapy in the treatment of threshold retinopathy of prematurity. Ophthalmology. 1998;105(9):1628–1631.
Laser ROP Study Group. Laser therapy for retinopathy of prematurity. Arch Ophthalmol. 1994; 112(2):154–156.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.