17.1 Goals

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  Induce regression of active retinopathy of prematurity (ROP).

  
  
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  Avoid complications including macular dragging and tractional retinal detachment.

17.2 Advantages

Laser photocoagulation has numerous advantages over the alternative therapies for ROP: cryotherapy and anti-vascular endothelial growth factor (anti-VEGF) agents. Cryotherapy has largely been abandoned as a treatment for ROP as laser therapy has a higher success rate and improved visual outcomes compared to cryotherapy. ¹ In addition, cryotherapy induces significantly greater amounts of myopia in the long term compared to laser. ² Anti-VEGF therapy is a more recently developed treatment option for ROP but requires an intravitreal injection, carrying the additional risks of infection, bleeding, retinal detachment, and damage to the lens. The long-term systemic side effects of anti-VEGF agents in premature infants is also unknown.

17.3 Expectations

Successful laser therapy in patients with Type I ROP includes:

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  Complete regression of active ROP

  
  
  
  
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    Without retinal detachment or distortion of posterior pole anatomy.

17.4 Key Principles

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  Successful treatment of ROP requires an accurate and timely diagnosis of Type I ROP.

  
  
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  Laser therapy (Fig. 17.1 and Fig. 17.2) is indicated in premature infants with Type I ROP to prevent potential vision loss from untreated ROP.

17.5 Indications

There are two primary treatment guidelines for ROP. The multicenter Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) study determined that treatment with cryotherapy should be initiated at threshold disease, ³ which was defined as at least 5 contiguous or 8 cumulative clock hours of stage 3 ROP in zone I or II with Plus disease.

Subsequently, the Early Treatment for Retinopathy of Prematurity (ETROP) study found better outcomes when treatment with laser therapy was initiated for Type I ROP, which was defined as ^{4 , 5} :

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  Zone I, any stage ROP with Plus disease.

  
  
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  Zone I, stage 3 ROP without Plus disease.

  
  
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  Zone II, stage 2 or 3 ROP with Plus disease.

The ETROP study also defined Type II ROP as:

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  Zone I, stage 1 or 2 ROP without Plus disease.

  
  
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  Zone II, stage 3 ROP without Plus disease.

Type II ROP is recommended to be monitored weekly.

Neonates with stage 4 or 5 ROP (partial or total retinal detachment) require treatment with scleral buckle and vitrectomy. The outcomes for stages 4 and 5 ROP are guarded at best, and so appropriate initiation of therapy is key to preserving vision.

17.6 Contraindications

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  Infants who are medically unstable for sedation and laser procedure.

  
  
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  Poor view due to poor dilation or intraocular hemorrhage.

17.7 Preoperative Preparation

ROP screening is performed based on the patient’s gestational age at birth, birth weight, and clinical status with follow-up examinations and determination for treatment based on examination findings. ⁶ Screening examinations require dilation with cyclopentolate 0.2% and phenylephrine 1%, which are usually available as a combination drop. ROP is graded based on the location and severity of disease.

The location of retinal vascularization defines the zone:

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  Zone I: A circle twice the distance from the center of the disc to the center of the macula and centered on the optic disc.

  
  
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  Zone II: The area encircling zone I, extending to the nasal ora.

  
  
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  Zone III: The remaining crescent of temporal retina.

The stage of disease is determined by the appearance of the region between the vascular and avascular retina:

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  Stage 1: Flat demarcation line.

  
  
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  Stage 2: Elevated ridge.

  
  
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  Stage 3: Ridge with extraretinal neovascularization.

  
  
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  Stage 4: Partial retinal detachment.

  
  
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  Stage 5: Total retinal detachment.

Plus disease is defined as the presence of dilated and tortuous vessels in two or more quadrants, and is often a deciding factor for treatment. Pre-plus disease may be noted as well, which is arteriolar tortuosity and venular dilation that is greater than normal but does not meet the definition of Plus disease. Aggressive posterior ROP (AP-ROP) involves tortuous vessels in all quadrants out of proportion to the extent of peripheral retinopathy, progresses rapidly, and has a poorer prognosis.

Once a neonate has any stage of ROP, the findings should be discussed with the patient’s family. This prepares the family for the potential need for future treatment. If laser therapy is indicated, then treatment recommendations, risks of treatment, and potential prognosis should be discussed.

17.8 Operative Technique

Laser treatment for ROP can be performed in the operating room under general anesthesia (Fig. 17.3) or at the bedside with monitored sedation. The optimal location depends on the stability of the infant and the preferences of the physician administering the anesthesia and the treating ophthalmologist. Coordination of care with the treatment team is crucial to ensure the best possible outcome for the patient.

1. 
   

   The baby should be positioned for the surgeon to be able to complete the laser treatment as efficiently as possible. The surgeon should have the ability to move around the infant circumferentially to allow for lasering of the entire retinal periphery. ⁷

   
   
2. 
   

   An indirect diode laser with 810 nm wavelength is recommended, as the diode laser has a decreased incidence of cataract formation at 0.003% compared to argon laser at 1 to 6%. ^{8 , 9 , 10} A 28-diopter condensing lens is the best lens to use for the larger field of view. A neonatal eyelid speculum and scleral depressor are also used.

   
   
3. 
   

   The laser is applied transpupillary in a near confluent pattern throughout the avascular retina to the ora serrata for 360 degrees. The laser burn should be dull-white in color. Typical settings are between 150 and 250 mW, pulse duration of 100 to 200 ms, with only 0.5–1 burn width between each laser spot. In cases of aggressive or persistent ROP, laser can also be applied posterior to the ridge. ¹¹ Generally, 2,000 to 3,000 spots are applied for the treatment of zone II disease, with additional spots for zone I disease.

   
   
4. 
   

   It is easiest to begin the laser at the most accessible and concerning area first, which is usually the temporal ridge. The laser can then be continued from the ridge anteriorly with gentle depression on the globe and continued for 360 degrees.

   
   
5. 
   

   Before concluding the laser treatment, the periphery should be re-examined for any skip areas, using a scleral depressor to ensure that treatment extends to the ora serrata for 360 degrees.