3.1. Setting

2.8. Indications for laser treatment in ROP

114 Laser Technology and its Applications

Cryotherapy for ROP, as a threshold disease [6].

cantly better than the threshold ones [2, 8, 9].

ROP and time is crucial for a correct screening.

retina is completed by 40–44 weeks PCA.

2.10. Indirect diode laser photocoagulation for ROP

confluent manner, with no space between them.

2.9. Timing of laser treatment for ROP

to very precise criteria [3].

37 weeks PCA [7].

The indications for ROP treatment were formulated for the first time by the Multicenter Trial of

The Early Treatment for ROP Randomized Trial Study affirmed that the criteria for treatment defined as "threshold" may no longer be the ideal indication for treatment. Therefore, the criteria for "pre-threshold" ROP were defined with the recommendation to initiate treatment also in these circumstances. The results of treatment in the pre-threshold ROP were signifi-

ROP is a model of acute retinal ischemia that is self-limiting, but if not addressed urgently, it may lead rapidly to retinal detachment and loss of vision. Because the window of opportunity during which laser treatment is likely to have a positive result is very short, timely recognition is crucial for a good outcome [7, 8]. Therefore, active screening should be carried out according

Basically, treatment should be performed at the point in the natural history of the disease when neovascularization can be reversed because once vitreo-retinal traction is initiated, the disease can no longer be controlled [2]. Therefore, knowing the correlation between the evolution of

The most vulnerable period, when ROP is at high risk of rapid progression starts at 34–35 weeks PCA up to 36–37 weeks PCA [8]. Usually, ROP does not develop during the first 2 weeks of life. The median age for the detection of stage 1 ROP is 34 weeks PCA, pre-threshold ROP appears around 36 weeks PCA and threshold ROP at about 37 weeks PCA. The vascularization of the

In conclusion, the interval for ROP detection is between 32 and 40 weeks PCA, but the critical phase, during which ROP may progress rapidly and has to be treated, is between 34 and

Laser therapies are carried out in the Neonatology Units, under sedation. Prior laser treatment, pupil dilation is achieved with a mixture of tropicamide 0.5% and phenylephrine 2.5%. The eyes are maintained open with a lid speculum throughout the procedure, the retina is visualized with a +20 or +28 diopter lens and the peripheral retina is accessed with a scleral indentor. Diode laser has an infrared emission of 810 nm, which is delivered transpupillary. Usually, the following laser parameters are used: 200 microns laser spot, with 200 ms duration and power between 100 and 300 mW, according to the retinal reaction. Laser spots are applied on all the surface of the non-vascular retina, from the anterior margin of the ridge to the ora serrata, in a This study was carried out at the "Iuliu Hatieganu" University of Medicine and Pharmacy (Cluj-Napoca, Romania) in the Ophthalmology and Neonatology Departments. All laser therapies were performed by two ophthalmologists in the Neonatology Department. Before enrollment in the study, informed consent was obtained from the parents/tutors. The study is approved by the Ethical Committee of "Iuliu Hatieganu" University of Medicine and Pharmacy.

#### 3.2. Study sample

This study includes all the consecutive premature infants with ROP who required laser photocoagulation between January 1, 2006 and December 31, 2017. The screening protocol was based on the following criteria: GA less or equal to 33 weeks and, BW less or equal to 1500 g. Premature infants beyond these criteria were also included in the screening if other risk factors were associated: prolonged oxygen administration with saturation over 93%, repeated transfusions, sepsis and the need of more than 6 days of mechanical ventilation for cardiorespiratory support. Eyes with stage 2 zone 2, stage 4a, 4b and 5 were not treated by laser and were therefore not included in the study sample.

Of these, 35 were from Cluj (31.81%) and 75 came from neighboring departments where laser

Indirect Diode Laser in the Treatment of Retinopathy of Prematurity

http://dx.doi.org/10.5772/intechopen.79828

117

GA was between 24 and 33 weeks (mean standard deviation: 28.30 2.87 weeks) and BW

Of the 110 preterm infants, 74 were the result of single pregnancies (67.27%) and 36 of multiple

PNA at treatment was between 5 and 13 weeks (mean: 8.38 1.93 weeks) and PCA at

Retinal laser photocoagulation was bilateral in 100 cases and unilateral in 10 cases, which makes for 210 lasered eyes. The 10 eyes in which laser photocoagulation was not performed fall into one of the following categories: stage 1 zone 2 ROP (four eyes), stage 2 zone 2 ROP (three eyes), stage 4a ROP (one eye), stage 5 ROP (one eye) and congenital atrophy (one eye). The three eyes with stage 2 zone 2 ROP were followed up closely, every 3 days and they regressed spontaneously with no need for laser therapy. ROP classification of the lasered eyes is as follows: stage 3 zone 2 ROP—167 eyes (79.52%), stage 3 zone 1 ROP—30 eyes (14.28%),

ROP regressed after laser treatment in 185 eyes (88.09%). Of the 185 eyes, regression was achieved after one laser session in 175 eyes (94.59%) and after two laser sessions in 10 eyes (5.40%). In all ROP cases with stage 3 zone 2 disease, regression was obtained after one laser

was between 500 and 1700 g (mean standard deviation: 1121 280.45 g).

treatment was between 32 and 41 weeks (mean: 37.02 1.65 weeks).

Characteristic No

Male 60 (54.54%) Female 50 (45.45%)

Cluj 35 (31.81%) Outside Cluj 75 (68.18%)

Single 74 (67.27%) Multiple 36 (32.72%) Mean SD gestational age (wk) 28.30 2.87 Mean birth weight (g) 1121 280.45 Mean SD PNA at treatment (wk) 8.38 1.93 Mean SD PCA at treatment (wk) 37.02 1

SD, standard deviation; PNA, postnatal age; PCA, postconceptional age.

Table 1. Premature infants treated by indirect diode laser photocoagulation for ROP.

was unavailable (68.18%).

pregnancies (32.72%).

AP-ROP—13 eyes (6.19%).

Gender

City of origin

Type of pregnancy

The data are summarized in Table 1.
