Typical Laser Treatment Technique as Summarized in the Literature1
Laser treatment should be instituted within 72 hours of the diagnosis of threshold disease.
Apply laser treatment to avascular retina immediately anterior to the ridge of extraretinal fibrovascular proliferation and extending to the ora serrata for 360° in all cases. A moderately intense, gray white burn is the desired target intensity. Laser settings to achieve the desired lesion intensity vary, but often range from a power of 150 to 400 mW and duration of 0.2 to 0.3 seconds. The mean number of burns have ranged from 410 to 1556, but can vary considerably depending on the posterior extent of the ridge and the resultant spot size.
Postoperative care: Immediately after laser treatment, steroid drops or ointment may be applied. Follow-up examinations are performed weekly until the regression of plus disease and fibrovascular proliferation occurs, then every 2 to 4 weeks until 3 months of age.
If plus disease persists for 2 weeks after treatment, and there are skip areas found in the avascular periphery, additional laser should be performed to complete a near confluent pattern for 360°. If plus disease persists and a stage 4A or 4B retinal detachment develops, the authors recommend supplemental laser to skip areas to quiet the plus disease as much as possible. This precaution may decrease the risk of intra or postoperative hemorrhage when a vitrectomy is performed.
Transscleral Retinal Photocoagulation (TSRPC)
The transscleral probe is applied to the external surface of the sclera and has a diode aiming beam that allows the targeted retina to be visualized using an indirect ophthalmoscope. To achieve a grayish, white burn, typical powers are between 500 and 750 mW and a pulse duration of 2 to 3 seconds. Advantages of transscleral treatment when compared with transpupillary treatment include the reduced risk of thermal injury to the iris and lens, and the ability to treat through media opacities such as vitreous hemorrhage and miotic pupils. Disadvantages include the technical difficulty in treating zone 1 disease just anterior to the ridge without conjunctival incisions. Although the vast majority of infants can be safely treated with transpupillary laser applications, transscleral diode laser may play a role in select cases.