Kerala Journal of Ophthalmology

: 2016  |  Volume : 28  |  Issue : 1  |  Page : 23--26

Study of incidence and risk factors of retinopathy of prematurity in tertiary care centre

Saravanan Jothi, Hemanandini Mangalanathan, Malligai Kamatchi, Vinetha Viswanathan, Swetha Karicheri 
 Department of Ophthalmology, Coimbatore Medical College Hospital, Coimbatore, Tamil Nadu, India

Correspondence Address:
Saravanan Jothi
Department of Ophthalmology, Coimbatore Medical College Hospital, Coimbatore - 641 018, Tamil Nadu


Purpose: Retinopathy of prematurity (ROP) is a preventable cause of childhood blindness. Identification of risk factors is essential for its early detection and management. Aim: The aim of this study was to analyze the incidence and risk factors of Retinopathy of Prematurity in preterm babies admitted in neonatal care unit over the period of one year. Materials and Methods: A clinical retrospective study was done among 259 preterm babies referred to our department from October 2014 to September 2015 for screening of ROP. Fundus examination with indirect ophthalmoscope (IDO) was done. Babies with manifestation of ROP were followed-up for progression and managed appropriately. Results: One hundred and forty-two (54.8%) babies were found to have ROP at various stages. In very low birth weight (VLBW) babies (<1000 g; n = 40), 34 (85%) had ROP, out of which 19 (55.9%) had significant disease. Among LBW neonates (<1500 g; n = 165), 108 (65.45%) had ROP, out of which 37 (34.3%) had significant disease (P < 0.05). In neonates less than 28 weeks (n = 33), 25 (75.8%) had ROP, out of which 14 (56%) had significant disease. Out of the 103 babies who had RDS, 61 (59.2%) babies developed ROP, out of which 20 (32.8%) had significant disease. Conclusion: Prematurity and LBW were found to be independent risk factors in development of ROP in neonates.

How to cite this article:
Jothi S, Mangalanathan H, Kamatchi M, Viswanathan V, Karicheri S. Study of incidence and risk factors of retinopathy of prematurity in tertiary care centre.Kerala J Ophthalmol 2016;28:23-26

How to cite this URL:
Jothi S, Mangalanathan H, Kamatchi M, Viswanathan V, Karicheri S. Study of incidence and risk factors of retinopathy of prematurity in tertiary care centre. Kerala J Ophthalmol [serial online] 2016 [cited 2022 Aug 9 ];28:23-26
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Full Text


Retinopathy of prematurity (ROP) is a vasoproliferative disease of the retina seen commonly in premature infants.[1] Prematurity has been regarded to be the most important risk factor of ROP, however, other factors such as low birth weight (LBW), high oxygen supplementation and its duration, respiratory distress syndrome (RDS), anemia, sepsis, and blood transfusion were also found to have significant association.[2] Because of advancements in neonatal intensive care in developing countries and higher survival rate of premature infants, the incidence of ROP has increased.[3] Unrecognized and untreated ROP will cause potential blindness in children. Hence, to prevent the adverse visual outcome and possible blindness, timely screening, recognition, and treatment of ROP is essential.

 Materials and Methods

A clinical retrospective study was conducted among 259 preterm babies admitted in the neonatal intensive care unit (NICU) as well as babies referring to the outpatient department (OPD) for ROP screening between October 2014 and September 2015. Ethical clearance was obtained for this study from the Ethical Committee of Coimbatore Medical College and Hospital. Preterm babies, LBW babies, and the babies who required supplemental oxygen were included in the study. The initial screening of the neonate was done either at 4 weeks of birth or 31 weeks postconceptually, whichever was earlier.[4] Prior to the fundus examination, mydriasis was achieved with 0.5% tropicamide and 2.5% phenylephrine eye drops instilled 3 times at 10 minutes interval. Indirect ophthalmoscopy with +20 D lens was done under topical anesthesia with the help of pediatric speculum and scleral indentation. In positive cases, staging of ROP was done according to the international classification of ROP [Table 1].{Table 1}

For the purpose of analysis, stage 1 disease was considered mild and all higher stages were considered significant disease. Babies with gestational age less than 32 weeks were considered as premature babies and the rest as mature babies. Babies with birth weight less than 1000 g and 1500 g were grouped as very LBW and LBW, respectively. The babies were followed-up weekly or biweekly till the vascularization reached zone 3, full retinal vascularization,[5] or the disease was regressing. Follow-up interval was different according to disease severity, with more severe disease requiring shorter follow-up interval.

Statistical analysis

The Statistical Package for Social Sciences (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp) was used to analyze the data. Group-wise frequency of ROP was measured in terms of gestational age, gender, and birth weight. Univariate analysis and Chi-square test were done to find the prevalence of ROP in each group as well as to assess the significance of association. Significant variables were included in multiple logistic regressions. Odds ratio (OR) and confidence interval (CI) for each significant risk factor were calculated.


Out of the 259 babies included in the study 116 (55.2%) were females and 143 (44.8%) were males. Mean birth weight of the babies was 1495 g, ranging from 600 to 3500 kg. Correlation between stages of ROP with birth weight and gestational age is presented in [Table 2] and [Table 3]. Most of the babies presented for screening were in the gestational age of 28–32 (45.6%) and birth weight of 1–1.5 kg (48.3%). One hundred and forty-two (54.8%) out of 259 babies were found to have ROP in various stages. A total of 66.9% of the babies with ROP were in stage 1 disease, 25.35% in stage 2, and 7.04% in stage 3, and only 1 case with stage 5. All babies had sthe ame stage of ROP in both eyes except 8 babies.{Table 2}{Table 3}

Birth weight and retinopathy of prematurity

In neonates with very LBW (n = 40), 34 (85%) had ROP, out of which 19 (55.9%) had significant disease. Similarly, in LBW neonates (n = 165), 108 (65.45%) had ROP, out of which 37 (34.3%) had significant disease, which was found to be statistically significant (P < 0.05) [Table 2].

Gestational age and retinopathy of prematurity

In premature neonates (n = 151), 98 (64.9%) had ROP, out of which 39 (39.8%) had significant disease. In neonates less than 28 weeks (n = 33), 25 (75.8%) had ROP, out of which 14 (56%) had significant disease [Table 3]. Out of 108 mature babies, 44 had ROP, and among them 26 had LBW and 20 had RDS. Among the mature babies (n = 108), 44 children were LBW (<1.5 kg), out of which 59.1% (n = 26) developed ROP (P = 0.001). RDS was present in 20 mature babies with ROP (52.6%).

Respiratory distress syndrome and retinopathy of prematurity

Out of the 103 babies who had RDS, 61 babies developed ROP (59.2%), out of which 20 had significant disease (32.8%).


Babies with preplus disease (n = 5) and plus disease (n = 4) were observed in the disease group. All the babies with plus disease had pupillary rigidity. All the cases with plus or preplus disease had ROP in zone 2. Five neonates with plus disease in stage 2 and 3 in zone 2 underwent laser panretinal photocoagulation (PRP). All these babies who underwent PRP were noted to have either regressing ROP or stable ROP during the follow up. One baby diagnosed with stage 3 with plus disease in initial screening had progressed to stage 5 with funnel RD despite laser treatment and was subjected to parsplana vitrectomy later. Foveal schisis (n = 2) and retinal hemorrhage (n = 5) were the other findings noted on examination.

Multiple logistic regression analysis showed gestational age and LBW to be independent risk factors for the development of ROP.


ROP is regarded as one of the important cause of preventable blindness in children.[6] Vision 2020 – right to sight gives special importance in preventing blindness in children. ROP has a typical progression pattern, however, early stages of the disease may regress spontaneously at any time.[7] As the disease progresses, vitreous hemorrhage and tractional retinal detachment can occur. The end stage of untreated ROP is the development of a dense, white fibrovascular plaque behind the lens with complete retinal detachment, where the child goes completely blind. Retinal vascularization normally proceeds from the optic disc to the periphery and is completed nasally by 36 weeks of gestation and on the temporal side by 40 weeks of gestation.[8] Among the risk factors, low gestational age and LBW are the most important factors that determine the development of ROP.[9]

The incidence of ROP in premature babies and LBW babies in our study is comparable with previous studies [Table 4]. A total of 65.45% of babies of less than 1.5 kg and 64.9% babies with gestational age group <32 weeks had ROP. Independent, significant association was found between the development of ROP and the above mentioned risk factors. Mean birth weight of babies having ROP was 1.34 kg and mean gestational age was 31.56 weeks, which was lower than the babies without ROP. RDS and LBW were the risk factors for development of ROP in mature (>32 weeks) babies. LBW, RDS, and sepsis were found to be strong independent contributing factors in development of ROP among mature babies. There was no significant gender difference in affected babies.{Table 4}

Six babies underwent laser therapy, who on follow-up were found to have either regressed ROP or stable ROP. Only one case which progressed very quickly to stage 5 was lasered and underwent vitrectomy. Hence, early laser treatment has been seen to halt the disease progression and help in regression.


Prematurity and LBW are independent risk factors in the development of ROP in neonates. Prematurity was a more important factor. At a given age group, those with LBW had more chance of developing ROP. Screening of the babies at 4 weeks of their birth and follow-up will allow us to detect significant ROP at their early stages, which will prevent further progression and blindness with appropriate treatment.[13]

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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