Laser Photocoagulation For Threshold Retinopathy Of Prematurity Research Articles

Laser photocoagulation (810 nm diode) for threshold retinopathy of prematurity: a prospective randomized pilot study of treatment to ridge and avascular retina versus avascular retina alone

The purpose of this study was to compare the structural outcome of laser treatment to avascular retina and ridge versus laser treatment to avascular retina alone in cases with threshold retinopathy of prematurity (ROP). A prospective, randomized, interventional, comparative study of consecutive cases referred to a single tertiary center was considered here. 50 infants with bilateral symmetrical threshold ROP were recruited into this study over a period of 3 years. Threshold ROP was defined as per CRYO-ROP study. Perinatal history details for all patients including significant maternal history were recorded. One eye of each patient was randomized (Microsoft Excel 2000) to one of the two treatment groups--laser treatment to avascular retina (Group A) or laser treatment to avascular retina and ridge (Group B). Laser treatment was performed with a 810 nm diode laser (Iris Medical Instruments, Inc. Mountain View, CA, USA). Treatment was continued until regression of ROP. Structural outcome was assessed at a minimum follow-up of 6 months and was considered favorable or unfavorable as per the CRYO-ROP study criteria. An unfavorable outcome consisted of either (1) a retinal fold involving the macula; (2) any retinal detachment involving zone 1; or (3) a retrolental mass that obscured visualization of the posterior pole. Secondary outcome measures included the difference in time to regression of ROP and complications of treatment between the two treatment groups. 100 eyes of 50 infants received laser photocoagulation for threshold ROP after randomization (50 eyes in each group). Of these 50 infants, 20 (40%) were female and 30 (60%) were male. A significant proportion of the children (46%) were conceived as twins. The average birth weight was 1360 ± 326 g (range 750-2200 g). The mean gestational age at birth was 30.72 ± 1.6 weeks (range 26-36 weeks). Zone I disease was present in 14 (14%) eyes and zone II in the remaining 86 eyes (86%). Threshold stage retinopathy (CRYO-ROP criteria) extending 360° (12 clock hours) was present in 21 infants (42%), 5 contiguous clock hours of stage 3+ in 14 infants (28%) and intermediate range in the remaining 15 infants (30%). At 6 months follow-up, 3 eyes (6%) in group A and 1 eye (2%) in group B had an adverse structural outcome; however, the time to regression of retinopathy 2.98 ± 1.5 weeks in group A and 3.12 ± 1.1 in group B (P = 0.889) and the rate of complications such as retinal hemorrhage, 3 eyes in group A and 4 eyes in group B, was comparable. Zone I eyes showed equal incidence of favorable anatomical outcome (85.7%) in each group. Laser treatment to ridge was found to be safe and effective in the treatment of threshold ROP in this short-term pilot study; however, it needs to be ascertained whether this treatment has long-term advantages over conventional laser treatment to avascular retina, as well as the long-term benefits of treatment to ridge.

Efficacy and safety of green laser photocoagulation for threshold retinopathy of prematurity

To report the efficacy and safety of green laser photocoagulation for threshold retinopathy of prematurity (ROP). We reviewed the clinical records of the neonates who had undergone green laser photocoagulation for threshold ROP at the Federal University of Pernambuco in Brazil between January 2004 and January 2006. All procedures were conducted with local anesthetic drops. The neonates were monitored throughout the procedure by a neonatologist. A frequency-doubled solid state laser, diode-pumped, with 532 nm wavelength was used. The presence of tunica vasculosa lentis or cataract were excluded before laser treatment. The following preoperative data were obtained for each patient: age, birth weight and the grade of ROP. Postoperative data included complications associated with the laser treatment, grade of ROP and evaluation whether further surgery was necessary due to failure of laser photocoagulation. Twenty-two neonates underwent photocoagulation with green laser for threshold ROP. A total of 31 eyes were included in the study. The mean gestational age was 30 +/- 3 weeks and the mean birth weight was 1120 +/- 490 g. Regression of the disease after laser therapy was observed in 30 eyes (96.7%). Despite treatment one eye presented stage 4A. Only 7 eyes required repetitive laser therapy. No adverse effects such as burning anterior segment tissues or bleeding in the anterior chamber occurred. No posterior segment side-effects were observed. Cataract formation was not observed at the last follow-up examination. Green laser photocoagulation remains an effective and safe alternative to red laser photocoagulation and to cryotherapy in the treatment of threshold ROP.

Pulsed mode versus near-continuous mode delivery of diode laser photocoagulation for high-risk retinopathy of prematurity

To compare structural and functional outcomes and efficiency of diode laser photocoagulation for retinopathy of prematurity (ROP) when delivered in a pulsed mode versus a near-continuous mode. A retrospective study was conducted of 138 patients who underwent diode laser photocoagulation for threshold ROP using either pulsed or near-continuous delivery. Laser-related complications and structural and functional outcomes were analyzed. Prospectively, time efficiency and total energy used were evaluated in nine infants with bilateral symmetric high-risk prethreshold ROP in which one eye of each infant was randomized to pulsed and the fellow eye to near-continuous delivery. There was no significant difference between groups with regards to prevalence of posterior disease (Zone 1 or posterior Zone 2) (p = 0.11), postoperative vitreous haze (p = 0.60), postoperative complications (p = 0.38), retinal detachment (p = 0.90), strabismus (p = 0.73), amblyopia (p = 0.69), or refractive error (p = 0.95). Mean time for treatment was 23 minutes using pulsed delivery versus 14 minutes per eye with near-continuous delivery (p < 0.001). The mean total power used per eye with pulsed mode delivery was 1.5 x 10(5) W versus 1.1 x 10(5) W with near-continuous delivery (p = 0.015). No differences in complications, functional outcome, or structural outcome were found between using pulsed mode and near-continuous mode diode laser delivery for high-risk ROP. Near-continuous laser delivery, in our hands, was more time-efficient and used less total power.

A comparison of laser photocoagulation with cryotherapy for threshold retinopathy of prematurity at 10 years: part 2. Refractive outcome

Objective To compare the refractive outcome of eyes treated with cryotherapy for threshold retinopathy of prematurity (ROP) with eyes treated with laser photocoagulation. Design Extended follow-up of a randomized controlled clinical trial. Participants One hundred eighteen eyes from 66 patients were randomly assigned to receive either cryotherapy or laser photocoagulation for threshold ROP. Twenty-five patients (44 eyes treated) were available for follow-up examination 10 years later. Intervention Cycloplegic autorefraction or retinoscopy was performed. Immersion ultrasound biometry (A-scan) was also performed, and an autokeratometer was used for keratometry. If an A-scan could not be tolerated or the patient was not cooperative, a B-scan through-the-lid biometry was performed. Corneal thickness was measured using optical coherence tomography. Main and secondary outcome measures Refractive error. In addition, anterior chamber depth, lens thickness, and axial length were measured. Central corneal thickness measurements and keratometric readings were also obtained. Result Eyes treated with cryotherapy were significantly more myopic than those treated with laser photocoagulation. When comparing patients with bilateral treatment, the mean spherical equivalent (SE) of eyes treated with laser was −4.48 diopters (D) compared with a mean SE of −7.65 D for eyes treated with cryotherapy (n = 15 pairs of eyes, P = 0.019). Cryotherapy-treated eyes had a mean axial length of 21.7 mm versus 22.9 mm for laser-treated eyes ( P = 0.024, n = 12 pairs of eyes). The anterior chamber depth and lens thickness averaged 2.86 mm and 4.33 mm, respectively, in the cryotherapy-treated eyes compared with 3.42 mm and 3.95 mm in the laser-treated eyes ( P < 0.001, n = 12 pairs for both measurements). There were no statistical differences in anterior corneal curvature and central corneal thickness between the two treatment modalities. Crystalline lens power bore the strongest correlation to refractive outcomes in both laser-treated ( r = 0.885, P < 0.001) and cryotherapy-treated eyes ( r = 0.591, P = 0.026). Although keratometric readings were higher than normal values in these eyes, there was no correlation to the degree of myopia. Conclusions Laser-treated eyes were significantly less myopic than cyrotherapy-treated eyes. Lens power seemed to be the predominant factor contributing to the excess myopia.

A comparison of laser photocoagulation with cryotherapy for threshold retinopathy of prematurity at 10 years: part 1. Visual function and structural outcome

Objective To assess visual and structural outcomes after laser photocoagulation and transscleral cryotherapy for threshold retinopathy of prematurity (ROP) after 10 years. Design Extended follow-up of a randomized controlled clinical trial. Participants One hundred eighteen eyes from 66 patients were randomly assigned to receive either cryotherapy or laser photocoagulation for threshold ROP. Forty-four eyes from 25 patients were examined for 10-year follow-up evaluations. Intervention Early Treatment of Diabetic Retinopathy Study (ETDRS) visual acuity, slit-lamp, and fundus examination; fundus photography; and B-scans (eyes with retinal detachments) were performed. Patients’ histories were taken to elicit past amblyopia therapy. Based on fundus photographs, independent observers graded the degree of retinal dragging as none, mild, moderate, or severe. Main and secondary outcome measures Best-corrected ETDRS visual acuity (BCVA). The degree of dragging was determined clinically and photographically. In addition, the presence of strabismus or amblyopia and/or any history of treatment for amblyopia were noted accordingly. Results Eyes treated with laser had a mean BCVA of 20/66 (Snellen equivalent), whereas cryotherapy-treated eyes had a mean BCVA of 20/182 (Snellen equivalent) ( P = 0.015, n = 42). Compared with eyes treated with cryotherapy, eyes treated with laser photocoagulation were 5.2 times more likely to have a 20/50 or better BCVA (95% confidence interval, 1.37–19.8, n = 42). Eyes treated with cryotherapy were 7.2 times (95% confidence interval, 1.54–33.6, n = 33) more likely to develop retinal dragging compared with laser treatment. By linear regression analysis, ETDRS visual acuity was inversely proportionate to the degree of retinal dragging in both laser ( r = −0.637, P = 0.006) and cryotherapy ( r = −0.517, P = 0.040) treated eyes. Among the 21 patients with favorable outcomes in both eyes, 13 had strabismus (62%) and 6 had received amblyopia therapy (29%). Ptosis, loss of cilia, and cortical cataract were among probable treatment-related complications that were noted in this study. Conclusions Overall, laser-treated eyes had better structural and functional outcome compared with eyes treated with cryotherapy.

A comparison of laser photocoagulation with trans-scleral cryotherapy in the treatment of threshold retinopathy of prematurity

Objective The goal of this study was to determine whether there was a significant difference between the visual outcomes of eyes with threshold retinopathy of prematurity (ROP) treated with trans-scleral cryotherapy compared to those treated with laser photocoagulation. Design Extended follow-up study of a prospective, randomized clinical trial. Participants Fifty-two patients with bilateral threshold ROP participated. Follow-up data were available for 25 of these patients. Intervention Patients were randomized to receive cryotherapy in one eye and laser photocoagulation in the other eye. Main outcome measures The best-corrected visual acuity of each eye was measured. Best-corrected visual acuities of 20/50 or better were classified as “good” clinical outcomes, whereas those 20/60 or worse were considered “poor” outcomes. A secondary outcome of this study was the spherical equivalent (SE) of each eye’s most recent refraction. Result At an average follow-up point of 5.8 years (range, 4.3–7.6 years), the odds that an eye treated with laser had a good clinical outcome were 6.91 times greater than for eyes treated with cryotherapy (95% confidence interval, 1.70–28.0; n = 21). Additionally, the laser-treated eyes were less myopic with a mean SE of −3.05 diopters compared to a mean SE of −5.08 diopters for the cryotherapy-treated eyes ( P = 0.0072, n = 23). Conclusion The authors’ study suggests that laser photocoagulation for threshold ROP was more likely to result in a good clinical outcome with better final visual acuity and less myopia compared to cryotherapy treatment.