Alok B S¹, Niveditha Alok Swamy^2*, Mahesh I Magdum³

¹Consultant Ophthalmologist and Cornea Surgeon, Department of Ophthalmology, Bangalore Nethralaya, Bengalore, Karnataka, INDIA.

²Assistant Professor, Department of General Medicine, MS Ramaiah Medical College, Bengalore, Karnataka, INDIA.

³Professor, Department of Ophthalmology, Jawaharlal Nehru Medical College, Belgaum, Karnataka, INDIA.

Email: nitukerodi@gmail.com

Table 1: Timing of First Screening Eye Examination Based on Gestational Age at Birth¹⁰⁷

First screening examination was carried out at 31 weeks of gestation or 4 weeks of age, whichever was later. For this purpose, gestational age was calculated from the last menstrual period.

Table 5: DISTRIBUTION AS PER BIRTH WEIGHT

Table 6: BIRTH WEIGHT AND ROP

         Figure 5: DISTRIBUTION OF ROP AS PER BIRTH WEIGHT            Figure 6: DISTRIBUTION OF MEAN BIRTH WEIGHT TO ROP

Table 7: BIRTH WEIGHT AND STAGE OF ROP

Figure 7: Distribution Of Mean Bt Wt To Stages of ROP

GESTATIONAL AGE AND ROP:

The gestational age of the ROP babies ranged from 28 -34 weeks (mean 31.38 ±1.63 weeks), while that of non-ROP babies ranged from 30-38 weeks (mean 33.31 ± 1.74 weeks). The incidence of ROP was 26.32% in babies born ≤ 32 weeks of gestational age.

Table 8: DISTRIBUTION OF GESTATIONAL AGE

Table 9: GESTATIONAL AGE AND ROP

         Figure 8: FREQUENCY OF ROP TO GESTATIONAL AGE      Figure 9: DISTRIBUTION OF MEAN GESTATIONAL AGE TO ROP

Table 10 :

Figure 10: DISTRIBUTION OF MEAN GESTATIONAL AGE TO STAGES OF ROP

Table 11: FRESH FROZEN PLASMA VS ROP

Table 12: PREGNANCY INDUCED HYPERTENSION VS ROP

Table 13: FETAL DISTRESS VS ROP

Table 14: HYPOTENSION VS ROP

Table 15: ANAEMIA VS ROP

Table 16: METABOLIC ACIDOSIS VS ROP

DISCUSSION

Retinopathy of prematurity (ROP) is a vasoproliferative disorder affecting premature infants. It is one of the most common causes of visual loss in children and can lead to lifelong vision impairment and blindness.⁶

Out of 45 million blind people in the world today, there are about 1.4 million blind children. ROP afflicts over 3,00,000 infant’s worldwide². In developing countries like India, the incidence of ROP has been reported at 24-47 % among high risk preterm infants. It is important not only in terms of economic burden, but in its severe social implication, which is very long in terms of blind years. Among the preventable causes of blindness in children (57%), ROP figures very high in the agenda. Low birth weight and gestational age were found to be the most important risk factors for the development of ROP.⁷ We screened babies admitted to our NICU with birth weight ≤ 1500g and gestation ≤ 32 weeks. Infants with birth weight >1500g and gestation more than 32 weeks were screened only if they had additional risk factors. In an article, Chawla, et al. has suggested the same screening criteria.

INCIDENCE: With neonatalogical units equipped with the state of art technological background and highly qualified personnel providing optimum care of extremely immature newborns, ROP incidence is on a rise. The overall incidence in the present study was found to be 16% with only one case of severe ROP (APROP). It is of current knowledge that aggressive posterior ROP seems to occur especially among smaller and more immature patients. In our study the baby which developed APROP, the birth weight was 1500 gms and gestational age was 33 weeks. In the CRYO-ROP study the incidence of the disease in a group of premature newborns with a birth weight <1251gms was 65.8% and 81.6% for infants of less than 1000 g birth weight¹⁶. In the ETROP (multi centric) study done 15 years later the overall incidence of ROP was found to be 68% in babies with birth weight <1251 gms. The overall incidence of more-severe ROP (prethreshold) was 36.9% among infants with ROP in the ETROP Study, whereas the incidence was 27.1% for patients in the CRYO-ROP Study who developed ROP.⁸ The incidence of severe form of the disease (Threshold disease) is decreasing. Agarwal and co-workers found a drop from 46 to 21% in their study over a period of 7 years. A Danish study found a statistically significant decrease in incidence of ROP in infants weighing more than 1250gm. Similar observations were made in multicentre study in UK. Nair and colleagues, Gupta and co-workers found no cases of ROP in babies weighing more than 1250gm.

Post Conceptional Age at First Examination: Post Conceptional Age at First Examination among ROP babies ranged from 33 – 38 weeks (mean 35.69 ± 1.58 weeks), while that of non-ROP babies ranged from 34 – 41 weeks (mean 37.38 ± 1.78 weeks). Early examination was significantly associated with chances of early detection of ROP (p = 0.016) in the present study.

RISK FACTORS: In our study Birth weight, Gestational age, Oxygen, Respiratory distress Syndrome, Transfusion and Apnoea of Prematurity were found to be significant risk factors on Chi Square analysis. On Univariate analysis, risk factors associated with ROP were Oxygen, RDS andTransfusion(FFP/Platelet) whereas on multivariate analysis, RDS was found to be an important risk factor. Using the forward method Oxygen and Transfusion were also found to be significant on Multivariate analysis.

Birth Weight and Gestational age:

In our study both low birth weight (p=<0.001) and prematurity (p= 0.004) were found to be significant risk factors for the development of ROP. The birth weight of the ROP babies ranged from 1000-1500 gm (mean 1272.81 ± 143.67 gm), while that of non-ROP babies ranged from 1100-2100 gm (mean 1642.80 ± 216.60 gm). Lower birth weight was significantly associated with increased incidence (p = <0.001) of ROP. The incidence of ROP was 40% in babies weighing ≤ 1500gm at birth. The gestational age of the ROP babies ranged from 28 -34 weeks (mean 31.38 ±1.63 weeks), while that of non-ROP babies ranged from 30-38 weeks (mean 33.31 ± 1.74 weeks). The incidence of ROP was 26.32% in babies born ≤ 32 weeks of gestational age. Gestational age was found to be a significant risk factor for the development of ROP (p=0.004) in this study.

Oxygen: In our study oxygen was found to be significant risk factor for the development of ROP on Chi square analysis (p=0.005), on univariate analysis and also on multivariate analysis. Out of 100 babies screened 59 were given O2 and 15 (25.42%) babies developed ROP. The causal link between ROP and supplemental oxygen has been confirmed by controlled trials and clinical studies. Gunn analyzed data from their low birth weight survivors and found a significant association between the more severe grade of cicatrical disease and duration of oxygen therapy. Kinsey noted that concentration of oxygen administered was significantly associated with ROP in infants under 1200gm. When comparing mean Pa02 levels in normal infants and in ROP infants, he found differences only in babies of low birth weight and only Pa02 levels greater than 150mmHg. However, a safe level of oxygen usage has not been defined, keeping Pao2 <100 mm Hg is recommended preferably between 50 and 70mm Hg and saturation between 90-95%. Preliminary work has suggested that continuous oxygen monitoring may reduce the incidence of ROP.

RESPIRATORY DISTRESS SYNDROME AND ROP: Out of 100 babies screened 55 had RDS and 14 (25.45%) babies developed ROP. RDS was found to be a significant risk factor for the development of ROP (p = 0.009). RDS was also found to be significant on univariate and multivariate analysis. Gupta et.al reported ROP in 33% of babies with RDS. Gupta et.al, Akkoyun et.al also found RDS to be a significant risk factor for the development of ROP.

TRANSFUSION: Out of 100 babies screened, 27 were given transfusion (either FFP / Packed cell/ Platelet) and 9(33.33%) developed ROP. Transfusion was found to be a significant risk factor for the development of ROP in this study (p=0.004). Transfusion was also found to be significant on univariate and multivariate analysis in our study. A potential role for blood transfusions and /or anaemia in the pathogenesis of retinopathy of prematurity (ROP) has been suggested. However a number of prospective, randomised, trials have failed to show a link between ROP and anaemia or transfusions. Dutta et.al reported that packed cell and double volume exchange transfusion in the neonatal period as a major risk factor for the development of ROP.⁹

Apnoea of prematurity: Out of 100 babies screened, 24 babies had AOP and 7(29.17%) developed ROP. AOP was found to be a significant factor for the development of ROP in this study (p=0.044). Agarwal et. al (54.1%), Gupta et.al(54.5%) found apnea to be a significant risk factor for the development of ROP. In a study by Kim et al., they found that apnoea independently increased the incidence of ROP. Furthermore, frequent apnoeic attacks increased the progression of pre-threshold ROP to threshold ROP. A higher incidence of hypoxemia and apnoeic episodes requiring bagging was found among infants with severe ROP than in a control group. Similarly in a study by Chen et al. they found that apnoea was one of the independent risk factors of ROP. Its appropriate management might reduce the incidence of ROP.¹⁰

Other risk factors: In our study we did not find sepsis, phototherapy, PIH, fetal distress, hypotension, anaemia and metabolic acidosis to be associated with ROP as found in other studies.

LIMITATIONS OF THE STUDY: The sample size is small and may not represent all premature babies. To know the true incidence and risk factors involved it is advisable to undertake larger study over a period of years.

CONCLUSION

The present study reflects the problem of ROP in a tertiary care centre. The incidence of ROP in the present study is 16%. Out of 16 babies with ROP, only 3 babies (18.75%) were in stage 1, 11 babies (68.75%) were in stage 2,1 baby (6.25%) was in stage3 and 1 baby (6.25%) developed APROP. In our opinion, the effective management of retinopathy of prematurity requires a team effort of the neonatologist, ophthalmologist and the NICU staff. Along with regular screening, an effective control of oxygen delivery, reduction of apneic spells and their early recognition and effective management of RDS are required.

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