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PROSPECTIVE STUDY ON PREVALENCE OF RETINOPATHY OF PREMATURITY IN GANJAM DISTRICT

Dr. Deepika Priyadarshini, Dr Sabita Devi, Dr. Prangya Panda, Dr. B.N.R. Subudhi

INTRODUCTION :

Retinopathy of prematurity(ROP) is a vasoproliferative retinopathy that affects developing retinal blood vessels in very low birth weight premature infants (<1500 gms)[1]. Premature retina exposed to high concentration of oxygen, followed by abrupt withdrawal, easily undergoes uncontrolled vasculo-fibrotic proliferation and eventually results in retinal detachment[2]. It begins to develop between 32 to 34 weeks after conception, regardless of gestational age at delivery and has two distinct phases[3]. During the first acute phase, the normal vasculogenesis of the retina is disturbed by the relative hyperoxia of the extrauterine environment. This causes vaso-obliteration and non-vascularisation of some areas of anterior retina[4]. The subsequent hypoxia causes a second chronic phase, characterised by the proliferation of vascular and glial cells, arteriovenous shunt formation, occasionally leading to involution or permanent cicatricial changes and visual impairment[5,6]. The key pathological change is local ischemia with subsequent peripheral retinal neovascularisation. This may regress completely or leave sequelae like myopia, strabismus, anisometropia, amblyopia, glaucoma and cataract[7].  In its more severe forms, it results in severe visual impairment or blindness, both of which carry a high financial cost for the community but also a high individual cost by affecting the normal motor, language, conceptual and social development of the child.

Today it is well known that oxygen therapy is not the single causative factor but many other risk factors play a causative role in the pathogenesis of retinopathy of prematurity[8,9]. Other causes are multiple gestation, anemia requiring blood transfusion, sepsis, hyperbilirubinemia, hyaline membrane disease, respiratory distress syndrome, exchange transfusion, intraventricular haemorrhage etc[7,10,11].

In India with the development of neonatal intensive care units, premature infants with extremely low birth weights are surviving and are at highest risk of developing retinopathy of prematurity[12]. Timing is one important factor that makes the treatment successful in retinopathy of prematurity, because the disease can advance very quickly and delayed treatment reduces the chances of success[13]. Till date there have been very few studies on the prevalence of retinopathy of prematurity in Orissa. Hence this study was undertaken to find the prevalence and the risk factors for retinopathy of prematurity.

MATERIAL AND METHOD:-

This prospective cross-sectional observational study was done in the Department of Ophthalmology, M.K.C.G. Medical College and Hospital, Berhampur from august 2016 to april 2018. Neonates born at or before 32 weeks of gestation and/or <1500 gms birth weight admitted in neonatal intensive care unit were included in the study along with neonates born after 32 weeks gestation or birth weights between 1.5 kg & 2 kg if they had any unstable neonatal course with risk factors like ventilation, oxygen requirement, use of surfactant, septicaemia, hyperbilirubinemia, intraventricular hemorrhage, patent ductus arteriosus, exchange transfusion, apnea and use of blood products. Neonates > 32 weeks of gestation with a stable neonatal course. children with major congenital malformation, chromosomal aberration and any fatal disease were excluded from the study. Infants who were having unilateral or bilateral retinal or choroidal disease (excluding retinopathy of prematurity) or media opacity obstructing the fundal view or those infants who were highly dependent on oxygen and could not be removed from the incubator for examination were also excluded from study.

Ethical clearance was obtained from the hospital ethics committee and informed consent from the parents was obtained. History of all enrolled neonates was taken which included a detailed birth history, number of days of oxygen exposure, any significant positive investigations (C Reactive Protein), history of any blood transfusion, hyperbilirubinemia etc. Unstable neonates were screened in neonatal care unit & stable/discharged infants were screened in the outpatient department of ophthalmology.

The first screening was done between 25 – 30 days after birth or at 31 – 33 weeks post-conceptional age whichever is later. Retinopathy was graded into stages and zones as per the International classification for retinopathy of prematurity. Followup was conducted according to the findings of first examination. If the initial examination showed no changes of retinopathy of prematurity, the infant was followed up at an interval of 2 – 3 weeks until the vessels reached the ora serrata or till 45 weeks of gestation. If changes of retinopathy of prematurity were noted on initial examination the infant was followed up according to the severity of retinopathy of prematurity.

STATISTICS:-

      Numerical data like birth weight, gestational age at birth etc were presented as mean scores and  Student’s T test was used to compare the means between two groups (case and control). Entire data was calculated on 95% CI. A p value <0.05 was considered significant.

 RESULTS:-

A total of 123 infants who satisfied the inclusion criteria were enrolled in our study. Initial and follow up screening was conducted. However only 97 infants could be followed up and completed the study. 26 of the infants were lost to follow up. Thus our study showed a drop-out rate of 21.14%.

The weight of infants studied ranged from 850 – 1980 gms with a mean weights of 1430.93 gms with a standard deviation of 270.26 gms. Among the 97 infants enrolled 9 (9.3%) were ≤1000 gms, 51 (52.6%) were between 1000 – 1500 gms and 37 (38.1%) were >1500 gms. The gestational age of infants studied ranged from 26 – 36 weeks with a mean of 31.89 weeks with a standard deviation of 2.46 weeks. Among the 97 infants studied 29 (29.9%) were ≤30 weeks, 30 (30.9%) were between 30 – 32 weeks and 38 (39.2%) were >32 weeks.

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Figure 1: Prevalence of retinopathy of prematurity

Out of 97 infants who were studied, 19 infants (19.58%) were reported with some stage of ROP after the completion of the study. Among those 19 infants, 2 (10.52%) were in Stage 2 ROP, 1 (5.26%) was in Stage 3 ROP, 1 (5.26%) was in stage 4 ROP and 15 (78.94%) were in regressing Stage. Our study thus reported the prevalence of retinopathy of prematurity to be 19.58%.

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Table 1: Risk factors of Retinopathy of prematurity.

 

In our study 16 (84.21%) of the 19 infants who developed ROP had the birth weight ≤1500 gms as compared to 44 (56.41%) of the 78 infants who did not develop ROP. The difference was found to be statistically significant with (p value = 0.032). The mean birth weight of infants who developed ROP was 1218.158 gms with a standard deviation of 223.74 gms as compared to 1482.756 gms with a standard deviation of 255.864 gms in infants who did not develop ROP.

17 (89.47%) of the 19 infants who developed ROP were ≤32 weeks of gestation as compared to 42 (53.85%) of the 78 infants who did not develop ROP. The difference was found to be statistically significant with (p value = 0.03). Only 2 (10.53%) of the 19 infants who developed ROP were >32 weeks of gestation as compared to 36(46.15%) of the 78 infants who did not develop ROP. The mean gestation age of infants who developed ROP was 30.947 weeks with a standard deviation of 2.146 weeks as compared to 32.128 weeks with a standard deviation of 2.48 weeks in infants who did not develop ROP.

Out of 97 infants included in our study, 57 were males and 40 were females. Of the 19 infants who developed ROP in our study, 14 were males and 5 were females. We did not find any significant correlation between gender and development of ROP ( P value = 0.141).

Among the 97 infants screened in our study, 54 were exposed to oxygen more than 2 days, of which 15 (27.78%) developed ROP as compared to 4 (9.3%) of 43 infants who were exposed to oxygen for less than 2 days. Statistically this difference was found to be significant (P value = 0.023).

34 of the 97 infants screened in our study were diagnosed with septicaemia and C Reactive Protein levels positive. 11 (32.35%) of these 34 infants developed ROP as compared to 8 (12.69%) of 63 infants who were not diagnosed with septicaemia and CRP levels negative. Statistically this difference was found to be significant (P value = 0.02).

13 of the 97 infants screened in our study had received exchange transfusion. Our study found that 11 (84.61%) of these 13 infants developed ROP as compared to 8 (9.52%) of 84 infants who did not receive blood transfusion. Statistically this difference was found to be highly significant (P value < 0.001).

Out of 97 infants screened in our study, 23 infants were of multiple gestation. Our study found that only 2 (10.52%) of these 13 infants developed ROP as compared to 17 (22.97%) of 74 infants who were of singleton pregnancy. Statistically this difference was found to be not significant (P value = 0.318).

DISCUSSION:

Our study thus reported the prevalence of retinopathy of prematurity to be 19.58% which is comparable to various studies conducted all over the world. Hakeem AH et al. (2012) reported a prevalence of 19.2%[14]. K Lathiesh Kumar et al. (2017) found the prevalence of 19.2%[15]. Milad Azami et al. (2017) reported the prevalence of 23.5%[16].A more study carried out by Snigdha Sen et al. (2018) reported the  prevalence to be 22.58%[17].

Birth weight ≤1500 gms was found to be statistically significant risk factor for developing retinopathy of prematurity with a p value of 0.032. The mean birth weight of infants who developed retinopathy of prematurity was 1218.158 gms with a standard deviation of 223.74 gms as compared to 1482.756 gms with a standard deviation of 255.864 gms in infants who did not develop retinopathy of prematurity. This significant association between birth weight and retinopathy of prematurity reported by our study was comparable to several other studies. Recent studies conducted by Gholam Hossein Yaghoubi et al. (2017)[18], Milad Azami et al. (2017)[16], Oscar Onyango et al. (2018)[19] & Snigdha Sen et al. (2018)[17] have also found low birth weight to be an independent risk factor for developing retinopathy of prematurity.

Gestational age ≤ 32 weeks was also found to be statistically significant risk factor for developing retinopathy of prematurity with a p value of 0.03. The mean gestation age of infants who developed retinopathy of prematurity was 30.947 weeks with a standard deviation of 2.146 weeks as compared to 32.128 weeks with a standard deviation of 2.48 weeks in infants who did not develop retinopathy of prematurity. Studies conducted by Hakeem AH et al. (2012)[14], Ilham M Omer et al. (2014)[20], Bodhraj Dhawan et al. (2016)[21], Gholam Hossein Yaghoubi et al. (2017)[18], K Lathiesh Kumar et al. (2017)[15], Milad Azami et al. (2017) [16], Oscar Onyango et al. (2018) [19] & Snigdha Sen et al. (2018)[17] have also found low gestational age to be an independent risk factor for developing retinopathy of prematurity.

Duration of oxygen exposure > 2 days was found to be statistically significant risk factor for developing retinopathy of prematurity with a p value of 0.023. Thus longer duration and unmonitored oxygen exposure is a risk factor for retinopathy of prematurity. Studies conducted by Kumar P et al. (2011)[22], Hakeem AH et al. (2012)[14], Ilham M Omer et al. (2014)[20], Bodhraj Dhawan et al. (2016)[21], K Lathiesh Kumar et al. (2017)[15], Milad Azami et al. (2017)[16] & Snigdha Sen et al. (2018)[17] have also found low duration of oxygen exposure to be an independent risk factor for developing retinopathy of prematurity.

Gender did not show any association with the development of retinopathy of prematurity (P value = 0.141). There are no studies till date that found a significant association between gender and development of retinopathy of prematurity.

Infants diagnosed with sepsis along with C Reactive Protein levels + were also found to be significantly associated with development of retinopathy of prematurity with a p value of 0.02. Recent studies conducted by Reza Saeidi et al. (2009)[23], Kumar P et al. (2011)[22], Hakeem AH et al. (2012)[14], Ilham M Omer et al. (2014)[20], Samatha Shetty et al. (2015)[24], Milad Azami et al. (2017) [16] & Snigdha Sen et al. (2018)[17] have also found sepsis as a significant risk factor for developing retinopathy of prematurity.

Exchange transfusion was also found to be a highly significant risk factor for developing retinopathy of prematurity with a p value of <0.001. Studies conducted by Hakeem AH et al. (2012)[14], Ilham M Omer et al. (2014)[20], K Lathiesh Kumar et al. (2017)[15], Milad Azami et al. (2017) [16], Oscar Onyango et al. (2018)[19] & Snigdha Sen et al. (2018)[17] have also found exchange transfusions to be an independent risk factor for developing retinopathy of prematurity.

Our study did not report any significant association between siblings of multiple gestation and development of retinopathy of prematurity (P value = 0.318). Rohit Charan et al.  (1995) also didn’t find any significant relation between multiple birth and development of retinopathy of prematurity [25]. This is in contrast with study carried out by Sood V et al. (2012) in which multiple gestation was confirmed as an independent risk factor for retinopathy of prematurity. Sicker the twin infant more the chances of developing retinopathy of prematurity than the other sibling[26]. Snigdha Sen et al. (2018) [17] also found twin delivery to be independent risk factor for retinopathy of prematurity.

Our study also did not find any significant association between hyperbilirubinemia and development of ROP (P value = 0.614). This is in contrast with study carried out by Samatha Shetty et al. (2015) who found hyperbilirubinemia to be significantly associated with development of retinopathy of prematurity[24].

 

CONCLUSION:

The Prevalence of Retinopathy of Prematurity (ROP) was found to be 19.58% in our study. Along with prematurity and low birth weight, duration of oxygen exposure, exchange transfusion and septicaemia were found to be significant risk factors in our study. Multiple gestation and hyperbilirubinemia were not found to have any significant association with development of retinopathy in our study. Retinopathy of prematurity is emerging as a leading cause of childhood blindness. Timely screening, regular follow-up, early detection and intervention is the best way to decrease the prevalence of this preventable cause of childhood blindness.

KEYWORDS: Retinopathy of Prematurity, low birth weight, low gestational age, oxygen exposure, exchange transfusion.

 

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ABBREVIATIONS: ROP – Retinopathy of prematurity

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