Atlas of Procedures in Neonatology, 4th Edition

Miscellaneous Procedures

49

Laser for Retinopathy of Prematurity

William F. Deegan

Marijean Miller

  1. Classification of Retinopathy of Prematurity (ROP) (1)
  2. Location (Fig. 49.1)
  3. Zone I: Circle whose center is the optic disc and whose radius is twice the distance from the optic disc to the center of the macula
  4. Zone II: Circle whose radius extends from the optic disc to the nasal ora serrata and is peripheral to Zone I
  5. Zone III: Temporal crescent of retina anterior to Zone II
  6. Extent of disease

The retina is divided into 12 equal segments, or clock hours. The extent of retinopathy specifies the number of clock hours involved.

  1. Staging the disease (1,2) (Figs. 49.2 and 49.3)
  2. Stage 1—demarcation line: A flat white line in the plane of the retina, separating avascular retina anteriorly from vascularized retina posteriorly
  3. Stage 2—ridge: Elevated fibrovascular tissue extending out of the plane of the retina and separating the vascularized and avascular retina
  4. Stage 3—neovascularization of the ridge: Neovascular tissue extending from the ridge into the vitreous. This tissue may cause the ridge to appear ragged or “fuzzy” (Fig. 49.2).
  5. Stage 4—retinal detachment: A separation of the retina from the underlying choroid. Usually, traction by the vitreous, through the presence of neovascular tissue, pulls the retina away from its underlying attachments. The intervening (subretinal) space fills with a proteinaceous fluid. A stage 4A detachment spares the macula; a stage 4B involves the macula. Retinal detachments in ROP require more extensive intervention, i.e., incisional surgery (scleral buckling and/or vitrectomy) (3).
  6. Stage 5—total retinal detachment: Retinal tissue becomes inextricably bound to reactive vitreous and is pulled by the vitreous into the retrolental space (hence the older term, retrolental fibroplasia).
  7. “Plus” disease: Dilation and tortuosity of retinal vessels due to high-flow shunting in advanced ROP. This is seen best in the posterior pole.
  8. “Threshold” ROP: Traditionally (CRYO-ROP) defined as 5 contiguous or 8 total clock hours of stage 3 with Plus in Zone(s) I and/or II. Any stage 3 or any Plus in Zone I ROP should be treated. The Early Treatment for Retinopathy of Prematurity (ET-ROP)

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Study (4) devised a risk score that further stratifies “threshold” and suggests earlier, “prethreshold” treatment in some infants. These include babies with stage 2–3 with Plus disease in Zone II.

 

FIG. 49.1. Scheme of retina of right eye (RE) and left eye (LE), showing zone borders and clock hours employed to describe location and extent of retinopathy of prematurity. (From 

Committee for Classification of Retinopathy of Prematurity. An international classification of retinopathy of prematurity. Arch Ophthalmol. 1984;102:1130

, with permission.)

 

FIG. 49.2. Dilated, tortuous vessels end in vascular shunts at a thickened ridge of fibrovascular tissue. Avascular retina lies anterior to the ridge.

  1. Additional features: Iris vascular engorgement (Fig. 49.3) and pupillary rigidity (manifested by poor dilation after mydriatic instillation) (5) are harbingers of active, advanced ROP; corneal and lenticular opacity can be seen in the eyes of any premature infant regardless of the presence of ROP.
 

FIG. 49.3. Dilation and tortuosity of iris vessels may be seen in severe threshold retinopathy of prematurity.

  1. Screening for Retinopathy of Prematurity (2)

Indirect ophthalmoscopy with scleral depression is the only method that can accurately screen and monitor babies with ROP. All babies born at <1,500 g and/or 32 weeks' or less gestational age should be screened, and infants weighing >1,500 g or more than 32 weeks' gestation should be considered for screening if they have had a particularly unstable clinical course, e.g., those requiring cardiopulmonary support. The exams are done at the bedside with the assistance of the baby's nurse.

The timing of the first exam varies with gestational age. The initial examination for infants born between 22 and 27 weeks' gestational age is at 31 weeks postconceptional age (gestational age at birth plus chronological age). Infants born later than 27 weeks' should be screened initially 4 weeks after birth.

Follow-up exams depend on the retinal findings as classified by the International Classification of ROP. Table 49.1 has been adapted from the joint policy statement of the American Academies of Pediatrics and Ophthalmology, and the American Association for Pediatric Ophthalmology and Strabismus (2).

Babies whose clinical condition deteriorates should be followed closely, i.e., weekly, as late reactivation and worsening are possible.

  1. Indications for Laser (2,4,6)
  2. The guidelines for consideration of ablative treatment for ROP have been revised recently, according to the Early Treatment for Retinopathy of Prematurity Study.
  3. Zone I: Any stage of ROP with Plus disease or stage 3 without Plus disease
  4. Zone II: Stage 2 or 3 ROP with Plus disease
  5. Babies who meet the traditional definition of threshold in Zones II and III according to the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP): stage 3 ROP in Zone I or II in 5 or more continuous clock hours or 8 cumulative clock hours, with Plus disease
  6. Treatment is recommended within 72 hours of detection of a stage of ROP requiring ablative therapy, when possible, in order to minimize the risk of retinal detachment.

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TABLE 49.1 Follow-up Examination Schedule (2)

Findings

Follow-up

Stage 1–2 in Zone 1
Stage 3 in Zone II

1 wk or less

Immature retina (no ROP) in Zone I
Stage 2 in Zone II
Regressing ROP in Zone I

1–2 wk

Stage 1 in Zone II
Regressing ROP in Zone I

2 wk

Immature retina (no ROP) in Zone II
Regressing or Stage 1–2 in Zone III

2–3 wk

  1. Contraindications
  2. Stage 4 to 5 ROP, in which case laser may be done (intraoperatively) in conjunction with incisional surgery (scleral buckle, vitrectomy, or both)
  3. Vitreous hemorrhage sufficient to obscure a view of the retina
  4. Instability of medical condition sufficient to make the stress of sedation and laser inadvisable
  5. Lethal medical illness
  6. Laser Treatment

Personnel

  1. Ophthalmologist
  2. Determines the need for treatment
  3. Administers topical anesthetic
  4. Ensures that all personnel present at the treatment are wearing laser safety goggles
  5. Performs the laser
  6. Watches for and treats ocular complications that may arise during and after the procedure
  7. Follows the baby postoperatively until ROP is resolved
  8. Neonatology fellow, attending neonatologist, or pediatric anesthesiologist
  9. Administers systemic sedative agents (midazolam, fentanyl, ketamine, or a combination)
  10. Monitors patient for and treats any systemic complications that develop during or after treatment
  11. Provides information to the ophthalmologist regarding the patient's overall condition throughout the procedure
  12. Assistant to the ophthalmologist
  13. Helps with laser and instruments
  14. Records the treatment parameters used during treatment
  15. Neonatal nurse
  16. Instills dilating drops several times in the hour preceding treatment
  17. Immobilizes the patient during treatment
  18. Monitors the patient's airway

Equipment

  1. Cardiorespiratory, blood pressure, and transcutaneous oxygen monitors
  2. Appropriate respiratory support (ventilator, laryngoscope and endotracheal tubes, face mask, self-inflating resuscitation bag, suction, and oxygen source)
  3. Emergency medications (atropine, epinephrine, bicarbonate, calcium, phenobarbital)

Note: Precalculation of weight-appropriate doses is helpful.

  1. Topical ocular anesthetic, e.g., tetracaine, proparacaine
  2. Cycloplegic/mydriatic eye drops: Cyclomydril (Alcon Laboratories, Fort Worth, TX, USA) (cyclopentolate hydrochloride 0.2% and phenylephrine hydrochloride 1%) or 0.5% cyclopentolate and 1% or 2.5% phenylephrine
  3. Calcium alginate-tipped nasopharyngeal applicators or Flynn depressor (Fig. 49.4), for scleral depression
  4. Balanced salt solution for rewetting cornea during procedure
  5. Neonatal eyelid speculum (Fig. 49.4)
  6. 28- and 20-diopter lenses
  7. Portable argon or diode laser (7,8) with indirect (headlamp) delivery system
  8. Appropriate laser safety goggles
 

FIG. 49.4. Lid speculae and Flynn depressor.

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  1. Precautions and Complications (Table 49.2)
  2. Ensure that laser is fully functional.
  3. If the infant is at high risk for an adverse event that would terminate treatment prematurely, treat the more advanced eye first (assuming both have threshold ROP).
  4. Discontinue feedings at least 4 hours before the procedure, or empty the stomach with an orogastric tube.
  5. Establish intravenous access for infusions of medications and intravenous fluids.
  6. Observe transcutaneous or saturation monitor carefully, and adjust administered oxygen appropriately.
  7. Stabilize the infant: Correct electrolyte imbalances, platelet deficiency, etc.
  8. Use only 1% phenylephrine if there is a history of hypertension.

TABLE 49.2 Complications of Laser for Retinopathy

Complication

Treatment/Action

Systemic: intra- and immediately postop

   Bradycardia

Interrupt treatment.
Assess airway, oxygen delivery.
Atropine 0.1 mg IV

   Hypoxia/cyanosis

Evaluate airway.
Administer supplemental oxygen.

   Apnea

Evaluate airway.
Gentle stimulation.
Administer supplemental oxygen.
Hand-ventilate (self-inflating resuscitation bag, face mask).

   Tachycardia

Assess pain control.
Administer additional analgesic.
Monitor blood pressure and perfusion.

   Hypertension

Assess pain control.
Administer additional analgesic.
If moderate, observe.
If severe, consider hydralazine 0.1 mg/kg IV

   Arrhythmia

Manage as appropriate for arrhythmia.

   Seizure (mechanism uncertain:? anticholinergic effect)

Supportive care.
Phenobarbital.

Ocular: intraop

   Closure of central artery

Relieve pressure on globe (stop scleral depression).

   Corneal clouding/abrasion

Rinse with balanced salt solution/saline.
Interrupt treatment.

   Retinal/vitreous/choroidal hemorrhage

Gentle pressure on globe (until arterial pulsations visible).
Avoid lasering blood.
May have to terminate treatment if extensive.

Ocular: postop

   Conjuntival hemorrhage

Observation.

   Conjunctival laceration

Antibiotic ointment t.i.d. for 3–4 d.

   Corneal abrasion

Antibiotic ointment t.i.d. for 3–4 d.
Follow with slit lamp exam with fluorescein.

   Hyphema

Topical cycloplegic and steroids.
Follow intraocular pressure closely.
Consider washout if high pressure, no resolution in 7–10 d.

   Retinal/vitreous/choroidal hemorrhage

Close follow-up.

Ocular: late

   Amblyopia, strabismus, myopia

Pediatric ophthalmology assessment 3–4 mo after treatment(s).
Educate parents prior to discharge re: need for regular ophthalmology follow-up.

IV, intravenously; t.i.d., three times per day.

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FIG. 49.5. Freshly lasered avascular retina.

  1. Wipe off any excess drops spilling onto the skin to avoid transcutaneous absorption (skin vessel blanching occurs with phenylephrine).
  2. Technique
  3. General preparation
  4. Instill eyedrops (per orders from ophthalmologist) into both eyes in the hour prior to procedure. Maximal dilation is critical for optimum laser; therefore, several (three or four) instillations of drops may be required, especially in eyes with neovascularization/vascular engorgement of the iris.
  5. Transport the patient to surgical suite or designated procedure room in the nursery.
  6. Ensure monitors are attached and functioning.
  7. Immobilize infant: Swaddle in a clean towel or blanket to immobilize arms and legs.
  8. Ensure that the intravenous tubing is accessible.
  9. Administer intravenous sedation.

If local anesthesia is to be used, a combination of topical (e.g., tetracaine, proparacaine) and systemic analgesic/sedative e.g. intravenous morphine, medications is administered prior to injection.

  1. Distribute laser safety goggles and dim overhead lights.
  2. Retract lids.
  3. Perform laser: Cover the avascular retina with confluent gray-white burns (Fig. 49.5).
  4. Have an assistant count and record the number of spots and the duration and power of each spot.
  5. Postoperative Care
  6. Instill 0.25% scopolamine hydrobromide in treated eye(s) daily for 3 to 5 days.
  7. Apply antibiotic–steroid preparation (e.g., tobramycin–dexamethasone) to treated eye(s) three to four times daily for 5 to 7 days.
  8. Monitor the patient with a cardiorespiratory monitor for 24 to 72 hours.
  9. Perform a dilated retinal exam 1 to 2 weeks after treatment.
  10. If opaque media are present at the time of laser, or if the pupil does not dilate adequately, complete treatment of the avascular retina may be impossible, and “skip areas” may be visible in the weeks after treatment. Treatment of these areas should be considered if there is not marked resolution of the adjacent plus disease and/or neovascularization.
  11. Follow the infant every 1 to 2 weeks until the ROP resolves completely. If at the time of discharge ROP is still present, ensure that the parents and the physicians responsible for the care of the infant after discharge are aware of the extreme importance of maintaining a regular schedule of outpatient examinations. Once the ROP has resolved completely, the baby should be seen by a pediatric ophthalmologist within 1 to 2 months to assess vision, ocular alignment and motility, refractive status, etc. Long-term follow-up over several years may be necessary (9,10,11 and 12).
  12. Postdischarge Care

A critical component of treatment is post-discharge care. It is imperative that infants who develop any stage of ROP, especially those with prethreshold stage 3 or those that have received treatment, are seen within 1 to 2 weeks of discharge, or as directed by the ophthalmologist involved in the baby's care. No baby with any ROP, or who has regressed ROP after treatment, should leave the neonatal intensive care unit (NICU) without a scheduled follow-up examination.

A careful, reproducible tracking system for arranging follow-up should be established by every NICU. A member of the staff of each NICU should be responsible for maintaining and periodically auditing this system.

Verbal and written instructions for follow-up should be given to the parents. Parents should be given a discharge form indicating their baby'sscheduled follow-up among their discharge instructions. The importance of scheduled follow-up should be prominently stated on the form.

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  1. Outcome

The benefit of ablative therapy for threshold ROP became apparent so quickly that enrollment for the CRYO-ROP study was halted after approximately half the planned number of infants were enrolled. The risk of adverse outcome (retinal detachment, macular fold) was cut in half in treated eyes.

Subsequently, as indirect argon and diode laser became available in the mid-1990s, the risk of adverse outcome in Zone II and III disease was reduced by another 50% (7,10). The outcome for eyes with Zone I disease, although poor, has improved with laser and incisional surgery (vitrectomy). Specifically, laser treatment of the posterior avascular retina can be accomplished easily and without necessitating conjuctival incisions, as in cryotherapy.

Treated eyes carry a risk of retinal dystopia, and myopia, and subsequent strabismus and amblyopia (11,12 and 13). To minimize the effect of refractive errors and strabismus, careful follow-up by a pediatric ophthalmologist is mandatory.

Premature infants are at risk for intracranial pathologies that may limit visual function. Pediatric ophthalmologists, neurologists, and others involved in the care of former preemies should be in frequent contact in order to address the often complex and changing visual deficits present in these children.

References

  1. Committee for Classification of Retinopathy of Prematurity.An international classification of retinopathy of prematurity. Arch Ophthalmol. 1984;102:1130.
  2. Section on Ophthalmology, American Academy of Pediatrics, American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus.Screening examinations of premature infants for retinopathy of prematurity. Pediatrics.2006;117:572–576.
  3. Trese MT.Scleral buckling for retinopathy of prematurity. Ophthalmology. 1994;101:23–26.
  4. Early Treatment for ROP 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;121:1684–1694.
  5. Kivlin JD, Biglan AW, Gordon RA, et al., for Cryotherapy for Retinopathy of Prematurity Group.Early retinal vessel development and iris vessel dilatation as factors in retinopathy of prematurity. Arch Ophthalmol. 1996;114:150–154.
  6. Multicenter Trial of Cryotherapy for Retinopathy of Prematurity Cooperative Group.Manual of Procedures. PB 88-163530. Springfield, VA: National Technical Information Service, U.S. Department of Commerce; 1985.
  7. Laser ROP Study Group.Laser therapy for retinopathy of prematurity. Arch Ophthalmol. 1994;112:154–156.
  8. Hunter DG, Repka MX.Diode laser photocoagulation for threshold retinopathy of prematurity. Ophthalmology. 1993;100:238–244.
  9. Cryotherapy for Retinopathy of Prematurity Cooperative Group.Multicenter trial of cryotherapy for retinopathy of prematurity: one-year outcome—structure and function. Arch Ophthalmol. 1990;108:1408–1416.
  10. McNamara J.Laser therapy for retinopathy of prematurity. Curr Opin Ophthalmol. 1993;4:76–80.
  11. O'Connor AR, Stephenson T, Johnson A, et al. Long-term ophthalmic outcome of low birth weight children with and without retinopathy of prematurity. Pediatrics.2002;109:12–18.
  12. Larson EK, Rydberg AC, Holmstrom GE.A population-based study of the refractive outcome in 10-year-old pre-term and full-term children. Arch Ophthalmol. 2003;121:1430–1436.
  13. Gilbert WS, Dobson V, Quinn GE, et al., on behalf of the Cryotherapy for Retinopathy of Prematurity Cooperative Group.The correlation of visual function with posterior retinal structure in severe retinopathy of prematurity. Arch Ophthalmol.1992;110:625–631.