A total of eight (8) third year ophthalmology residents from the PGH- Department of Ophthalmology and Visual Sciences underwent both the pretest and posttest evaluation for the determination of inter-observer agreement. Calculations using Kappa analysis were based on the residents’ assessment of retinal vessel dilatation and tortuosity in a set of pre-determined set of retinal pictures.

Table 1 and Table 2 show the outcomes of Kappa analysis to determine inter-observer agreement among the examining study group. For the pretest, a very good inter-observer agreement (κ=1.00) was computed for the retinal vessel tortuosity while for the retinal vessel dilatation, there was moderate inter-observer agreement (κ =0.552). On the other hand, posttest results revealed a kappa coefficient of 1.00, which indicates a very good inter-observer agreement for both retinal vessel tortuosity and dilatation.

The study examining group of ophthalmology residents were able to evaluate eighty-two (82) eyes of forty-one (41) premature babies for retinopathy of prematurity screening within the study period. The baseline characteristics of these neonates are tabulated below. Table 3

The study patients were equally represented in terms of gender, wherein 46% were males and 54% were females. The mean maternal age was 27, and ranges from 16-42 years. Most of the referred babies were born at 30 weeks age of gestation, with birthweights ranging from 890-2200 grams. Mean post-conceptional age upon referral for ROP screening was 36 weeks, and four (4) out of the 82 eyes that were examined had rubeosis on presentation.

Table 4 shows a summary of the existing identifiable risk factors associated with the development of retinopathy of prematurity in the preterm infants screened for ROP. Almost half (41%) of the referred preterm infants had exposure to oxygen with mechanical ventilation and nasal cannula/oxygen hood as the most common oxygenation method. Thirteen mothers (32%) had spontaneous premature rupture of membranes leading to early delivery. Meanwhile, almost 29% of the premature infants examined had a history of blood transfusion during the perinatal period.

The correlation between risk factors and the presence of abnormal retinal vessels as diagnosed by the study’s retina consultant were assessed using odd ratio computations with confidence intervals calculated at 95%. The summary of these computations is shown in Table 5.

Computations of odds ratio revealed that there is an increase risk in developing retinal vessel dilatation and/or tortuosity in the presence of the following risk factors, namely: (1) exposure to any method of oxygenation, (2) maternal infection, (3) pre eclampsia/eclampsia, (4) preterm premature rupture of membranes, (5) history of perinatal blood transfusion, (6) neonatal jaundice, (7) lower birth weight, and (8) earlier age of gestation. Most of the risk factors, however, did not show a statistically significant association for the development of abnormal retinal vessels, except for exposure to mechanical ventilation, birth weight and age of gestation.

Table 6 shows the correlation of various risk factors with the presence of a clinically diagnosed retinopathy of prematurity. Based on the computations of odds ratio at a 95% confidence interval, it has been shown that only age of gestation, birth weight, and transfusion are significantly associated with the presence of retinopathy of prematurity. Specifically, the risk of ROP is higher for those infants who have a history of perinatal transfusion, lower birth weight and earlier age of gestation.

Fisher’s exact test was computed to determine the correlation between retinopathy of prematurity and the presence of retinal dilatation and tortuosity. A significant association was seen between retinal vessel dilatation and tortuosity with the presence of retinopathy of prematurity (see Table 7). In general, retinal vessel tortuosity and dilatation are more common among infants diagnosed with retinopathy of prematurity than those without the disorder.

The comparison between the retinal vascular findings of the consultants versus the study examining group are summarized in Table 8 and Table 9. Results of the McNemar’s test showed that at p<0.05, there was no significant difference between the retinal vascular findings of the consultant which serves as the “ gold standard” and the third year ophthalmology resident in terms of identifying retinal vessel dilatation and tortuosity.

Retinopathy of prematurity (ROP), previously known as retro-lental fibroplasia, was initially described by Terry in 1942.12This was during the worldwide epidemic wherein an estimated 12,000 neonates in first world countries suffered visual loss from ROP.13 In the following decades, increasing number of ROP cases were reported in the developed world with the improvements in preterm survival rates and advancements in maternal, delivery, and neonatal care.14

The pathogenesis of retinopathy of prematurity is biphasic.13The first phase in ROP is initiated with delayed retinal vascular growth after premature birth. The abnormal vascularization of the developing newborn retina creates hypoxia. Phase II commences when the lack of oxygen triggers a release of factors, such as vascular endothelial growth factor (VEGF), which stimulate the growth of new and abnormal retinal vasculature characteristic of ROP.15

Retinopathy of prematurity has a multifactorial etiology.16The risk factors that have shown a significant association for the developing this condition include low gestational age,17 low birth weight,17 poor weight gain,12sepsis,12oxygen therapy or supplementation,18 and blood transfusions14,19Moreover, those having a history of anemia, interventricular hemorrhage, jaundice, respiratory distress syndrome, seizure, and congenital syndromes may also warrant referral for ROP screening. 7 Perinatal risk factors, on the other hand, that may also alert the pediatrician or neonatologist for the possible need for ROP screening include: maternal infection during the 3rd trimester, placenta previa, poor nutrition, pre-eclampsia/ eclampsia, premature rupture of membranes (PROM) ≥ 18 hours before delivery, and multiple gestation. 7 For this study, we have seen an increased risk of developing abnormal retinal vasculature in infants with exposure to any method of oxygenation, maternal infection, pre-eclampsia/eclampsia, preterm premature rupture of membranes, perinatal blood transfusion, neonatal jaundice, sepsis, low brithweight, and earlier age of gestation. These associations however, were not statistically significant except for exposure to oxygenation from mechanical ventilation, birthweight and age of gestation, which are good predictors for the presence of abnormal retinal vessels.

Prompt recognition of plus disease is crucial for timely treatment and management of retinopathy of prematurity.21In a study by Saunders in 1995, it was concluded that there was a highly significant correlation between the posterior pole vascular abnormalities and the severity of ROP in the retinal periphery.22 The detection of plus disease, specifically vessel dilatation, vessel congestion and arteriolar tortuosity, depends on the ophthalmologist's subjective evaluation. 23Pre-plus disease, on the other hand, was defined by the ICROP to be vascular abnormalities of the posterior pole that are insufficient for the diagnosis of plus disease but that demonstrate more arteriolar tortuosity and more venular dilatation than normal.24Wallace in 2000 showed that early vascular dilation and tortuosity judged insufficient for plus disease have prognostic significance in the early course of ROP. Those with mild vascular dilation and tortuosity had a significantly higher incidence of progression to laser treatment, stage 3 ROP, and plus disease.24Similar findings could be derived from the results of this study wherein a statistically significant positive correlation was seen between retinal vessel dilatation and tortuosity and the presence of retinopathy of prematurity. Those infants that have abnormal retinal vasculature are more likely to have retinopathy of prematurity in subsequent follow-ups. Furthermore, a higher incidence of retinopathy of prematurity are seen in premature babies who were born with a lower birthweight and earlier age of gestation, as well as in those who have had blood transfusion.

The detection of vascular and retinal changes in retinopathy of prematurity is hampered by technical difficulties. Therefore, the screening and management of retinopathy of prematurity is usually done by either a retina specialist or a pediatric ophthalmologist.25At present, there are limited reports on the possibility of screening done by non-ROP specialists. Most of the available studies done on this topic were ventured by researchers from developing countries with limited ROP specialists and screening resources similar to the Philippines. Azad in 2006 concluded that given adequate training, Indian general ophthalmologists and non-ophthalmologists (pediatricians and nurse practitioners) are independently reliable in detecting posterior pole changes in ROP babies using direct ophthalmoscope and can be provided with a screening protocol.5Another study by Saunders in 2000 reported that examination of the posterior pole blood vessels can be reliably performed by a non-ophthalmologist, using a direct ophthalmoscope, in situations where ophthalmological consultation is unavailable or difficult to obtain.22 Meanwhile, in study by Romero etal. in 2011, she stated that after training in the use of an indirect ophthalmoscope, pediatricians and neonatologists could reliably detect posterior pole retinal vessel changes for ROP diagnosis in Mexico. 26Our results suggest that with adequate training, ophthalmology residents who, eventually will be general ophthalmologists, can identify retino-vascular abnormalities associated with severe retinopathy of prematurity.

In a developing country like the Philippines where ROP specialists are few in number, a retinopathy of prematurity screening protocol with general ophthalmologists in the provinces serving as the first line of examiners could hypothetically be more cost-effective, comprehensive, and efficient. This scenario will ensure that every infant needing retinal examination for ROP could be examined immediately for posterior pole vascular abnormalities by adequately trained general ophthalmologists. An appropriate referral system to an ROP specialist could then be instituted to allow proper and timely transfer to a secondary or tertiary health institution, for all high-risk ROP cases that would need immediate and appropriate medical and/or surgical intervention. Moreover, it should be emphasized that the findings of a normal retinal vessels at the time of examination does not rule out the potential of developing ROP in the future. Thus, repeated retinal examinations are suggested to document normal retinal vessels repeatedly or any vascular changes necessitating referral until the criteria for termination for ROP screening are met. One, however, must also consider that for this referral system to be successful, emphasis on the need for ROP training in the national ophthalmology residency program should also be established. Ophthalmology residents, who will soon be the general ophthalmologists in the provinces, should be comprehensively taught the concepts and skills needed to identify ophthalmologic findings suggestive of ROP, using the appropriate equipment.

The limitations of this study are the small sample size and the sole utilization of retinal vascular dilatation and/or tortuosity as a manifestation of ROP. Since this study focused on a severe presentation of ROP, which is the presence of retinal vessel dilatation and tortuosity (plus disease) only, the results might not be applicable when evaluating less severe cases of retinopathy or prematurity.

Based on the results of this study, we conclude that given sufficient and in-depth training, third year ophthalmologists, who will be general ophthalmologists in the future, can reliably identify eyes at risk for severe retinopathy of prematurity on the basis of retinal vascular dilatation and/or tortuosity. While this scenario may be far from the ideal setting for ROP screening, the role of general ophthalmologists in the provinces who are able to examined referred preterm babies provides an indispensible resource in health institutions where an on-site ROP specialist is not available.