3.4. Statistical analysis

Epi Info 7 software (Centers for Disease Control and Prevention, Atlanta, GA) was used for the statistical analysis of the data. Frequencies for the following independent variables concerning the premature infant were calculated: gender, GA, BW, type of pregnancy (unique or multiple), PCA and PNA at treatment, ROP classification.

Odds ratio was used to interpret the results, and statistical significance was evaluated according to P value calculated with t test. Chi-square test was used if values over 5 were expected in 80% of the table cells, and Fisher exact test was used if values under 5 were expected in more than 20% of the table cells. P values less than .05 were considered statistically significant.

### 3.5. Results

In the previously mentioned period, we treated by indirect diode laser photocoagulation 110 premature infants of which, 60 were males (54.54%) and 50 were females (45.45%).

Of these, 35 were from Cluj (31.81%) and 75 came from neighboring departments where laser was unavailable (68.18%).

GA was between 24 and 33 weeks (mean standard deviation: 28.30 2.87 weeks) and BW was between 500 and 1700 g (mean standard deviation: 1121 280.45 g).

Of the 110 preterm infants, 74 were the result of single pregnancies (67.27%) and 36 of multiple pregnancies (32.72%).

PNA at treatment was between 5 and 13 weeks (mean: 8.38 1.93 weeks) and PCA at treatment was between 32 and 41 weeks (mean: 37.02 1.65 weeks).

The data are summarized in Table 1.

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

We performed laser therapy in the following situations: stage 3 zone 1 ROP, stage 3 zone 2 ROP, stage 2 zone 1 ROP and AP-ROP. Infants with AP-ROP were treated within 24 h from

All laser therapies were carried out under sedation in the Neonatology Unit. We used a portable indirect diode laser, with an emission of 810 nm, and laser energy was delivered transpupillary

A mixture of tropicamide 0.5% and phenylephrine 2.5% was instilled preoperatively, in order to dilate the pupils. In order to gain access to the retina, a lid speculum, a sclera indentor and a + 28

Indirect diode laser photocoagulation was performed with the following parameters: 200 microns laser spot, 200 ms duration and 150–300 mW power, according to the retinal reaction. The obtaining of a whitish retinal spot was aimed. Laser spots were applied in a confluent manner, with no space between impacts, to cover all the surface of the non-vascular retina, up

The first postlaser review took place 7 days after treatment. In case of regression, examinations continued every 5–6 days, until there was clear evidence of ROP regression. In case of regression failure, laser was completed immediately. The treated eyes were monitored with a frequency dictated by the clinical course of the disease, in order to address any risk of sequel.

Epi Info 7 software (Centers for Disease Control and Prevention, Atlanta, GA) was used for the statistical analysis of the data. Frequencies for the following independent variables concerning the premature infant were calculated: gender, GA, BW, type of pregnancy (unique or multiple),

Odds ratio was used to interpret the results, and statistical significance was evaluated according to P value calculated with t test. Chi-square test was used if values over 5 were expected in 80% of the table cells, and Fisher exact test was used if values under 5 were expected in more than

In the previously mentioned period, we treated by indirect diode laser photocoagulation 110

20% of the table cells. P values less than .05 were considered statistically significant.

premature infants of which, 60 were males (54.54%) and 50 were females (45.45%).

to ora serrata. The number of impacts varied between 1500 and 4000/eye.

were therefore not included in the study sample.

diagnosis and the rest of them within 48 h from diagnosis.

3.3. Medical intervention

116 Laser Technology and its Applications

diopter lens were used (Figure 2).

3.4. Statistical analysis

3.5. Results

PCA and PNA at treatment, ROP classification.

(Figure 1).

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%), AP-ROP—13 eyes (6.19%).

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


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

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

session. In stage 3 zone 1 ROP cases, regression was achieved after one laser session in 26 eyes, whereas in four eyes, two laser sessions were required to stabilize the disease. In AP-ROP cases, two laser sessions were necessary in 6 of the 13 eyes. Statistical tests proved that regression rate was significantly worse in AP-ROP eyes as compared with stage 3 zone 2 and stage 3 zone 1 ROP (odds ratio = 13.53, relative risk = 7.79, P < .001).

PNA at treatment were not statistically significantly different between the favorable outcome

Indirect Diode Laser in the Treatment of Retinopathy of Prematurity

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

119

Indirect diode laser photocoagulation proved its efficacy in ROP treatment. Our ROP regression rate is comparable to the ones cited in the literature [7]. The laser spots were applied on all the surface of the nonvascular retina, from the anterior margin of the ridge (when identifiable) up to ora serrata. In six eyes, we also placed laser posterior to the ridge for two reasons: to limit the extension of traction toward the posterior pole and to destroy an area, which is known to provide high levels of vasoproliferative factors because it is ischemic. We used this approach only in situations with advanced stage 3 disease in which we identified traction on the retina. All the six eyes had a good outcome (ROP regressed with no anatomical sequelae). Not all authors approve this strategy, arguing that it destroys more of the peripheral visual field with no proven

We delivered laser energy transpupillary in all cases. Laser can also be delivered through the sclera. In terms of efficacy, the two delivery methods are similar, but the transscleral approach is more traumatic. According to some authors, the transscleral approach carries no risk of cataract formation. However, in our series, we identified no case of cataract after laser delivered transpupillary. This is logic, taking into account that the absorption site of the infrared radiation is deep into the choroid, passing through the crystalline lens without being absorbed. Literature shows that lower GA and BW are associated with poorer outcomes of ROP [6]. These observations could not be verified in our series in which statistical tests proved no significant

Our study proves that the only factor with significant impact on ROP prognosis following laser was the ROP type. As such, AP-ROP cases had a significantly worse outcome as compared to the so-called classic ROP ones, which is in agreement with results cited in the literature [10]. The disappointing results that we obtained in AP-ROP cases with laser photocoagulation motivated us to start treatment in these cases with intravitreal Bevacizumab. This

Indirect diode laser photocoagulation of the non-vascular retina is a major tool in preventing ROP-related blindness. In order for the laser treatment to be effective, proper screening and timely recognition of ROP are crucial. Intravitreal anti-VEGF injections improved the outcome of laser treatment in severe forms of the disease, but laser remains the golden standard in the

This study was funded by grant number PED 156, Executive Agency for Higher Education,

and unfavorable outcome groups.

difference in terms of outcome according to GA and BW.

Research, Development and Innovation Funding, Romania.

attitude significantly improved our results.

4. Conclusion

treatment of ROP.

Acknowledgements

benefit [2].

Within the group of 25 eyes in which ROP failed to regress, 14 belonged to the male gender (56%) and 11 to the female gender (44%). The difference is not statistically significant.

The type of pregnancy (single or multiple) did not influence the outcome: ROP regressed in 132 of the 149 treated eyes coming from single pregnancies (88.59%) and in 53 of the 61 eyes coming from multiple pregnancies (86.88%).

Macular dragging was identified in three eyes, all from the AP-ROP group. Complications related to laser treatment were represented by two cases of mild anterior uveitis that responded promptly to mydriatic and anti-inflammatory eye drops.

We evaluated the timing of the laser treatment according to two parameters: PNA and PCA at treatment. Treatment was performed at PNA of 8 weeks or less in 118 eyes (56.19%) and at PNA of more than 8 weeks in 92 eyes (43.80%). Within the first group, ROP regressed in 101 eyes (85.59%), and within the second group, ROP regressed in 84 eyes (91.30%). According to the chi-square test, the difference is not statistically significant. PCA at treatment was equal or less than 37 weeks in 123 eyes (58.57%) and more than 37 weeks in 87 eyes (41.42%). Within the first group, ROP regressed in 112 eyes (91.05%), and within the second group, ROP regressed in 78 eyes (89.65%). This difference is not statistically significant, according to the chi-square test.

Within the group of 210 treated eyes, 84 belonged to premature infants with BW equal to or less than 1000 g (40%) and 126 eyes (60%), to premature infants with BW of more than 1000 g. ROP failed to regress in nine eyes from the first group (10.71%) and in 16 eyes from the second group (12.69%). The statistical tests proved that the difference is not significant.

GA was 28 weeks or less in 116 eyes (55.23%) and more than 28 weeks in 94 eyes (44.76%). Within the first group, ROP regressed after laser treatment in 104 eyes (89.65%) and in the second group ROP regressed in 81 eyes (86.17%). The difference is not statistically significant.
