Treatment of ROP with Threshold or Preª²threshold disease needs to be instituted as early as within 72 hours of detection as any delay will result in rapid deterioration, beyond treatment [1,3,4] . Treatment refers to the application of diode laser photocoagulation or cryotherapy to areas of nonª²vascularized retina.

    The purpose of this study was to report on the ROP screening program and findings of premature infants admitted to the Special Care Nursery (SCN) in University of Malaya Medical Centre (UMMC), which is a tertiary referral centre. We also wanted to study the yearly incidence of this condition and to see if there were changes in the pattern of ROP disease detected over a 3ª²year period. A comparison of our screening criteria will be made with the guidelines recommended by the Clinical Practice Guidelines on Management of Acute Retinopathy of Prematurity published by the Malaysian Ministry of Health and to assess if there is a need to change the screening criteria in UMMC.

    MATERIALS AND METHODS

    This was a retrospective study of premature infants born between 1 Jan 2003 to 31 Dec 2005 and subsequently admitted to the SCN in UMMC who underwent screening for ROP. The selection criteria for paediatrician referral of infants for ROP screening were gestational age ¡Ü32 weeks, birth weight <1251 grams, ventilaª²tion ¡Ý7 days and oxygen use for >1 month regardless of gestational age or birth weight. The first screening was performed at 4 weeks of chronological age.

    The outcome measures included the presence or absence of ROP and the worst stage of ROP recorded for each patient. Information collected into a proª²forma for each patient included gestation, birth weight, perinatal history, medical problems, ROP findings at each examination, the total number of screening examinations conducted and total number of treatment sessions. The disease staging was according to the ICROP staging for ROP[2].

    All the necessary clinical findings were entered into a standard proª²forma and the data were entered into the SPSS program 12.0 for statistical analysis. This study was approved by the Ethical Committee of the UMMC and was carried out in accordance with the Declaration of Helsinki.

    RESULTS

    The SCN ward in UMMC admitted a total of 221 babies born between 1 Jan 2003 to 31 Dec 2005. A total of 188 infants survived to undergo screening at the SCN in UMMC, based on the criteria for referral for ROP Screening of this hospital. The mean birth weight was 1105.28¡À300.56 grams (n=188) and mean gestation at birth was 29.18¡À2.54 weeks (n=188). ROP was detected in 55 out of 188 cases screened giving an overall incidence of 29.3% (55/188) (Table 1) and the differences in mean was significant for both gestaª²tion (P<0.001) and birth weight (P<0.001). The mean birth weight of our study patients who developed Stage 3 ROP was 833.5¡À206.5 grams (n=24, range: 600ª² 1545). All Stage 3 ROP occurred in Zone 2. Three patients developed Zone 1 disease and their mean birth weight was 512¡À128.3 grams (n=3, range: 432ª² 610).

    The breakdown of birth weight of the screened infants is shown in Figure 1. In 2005, a higher number of infants whose birth weight was 750 grams or less were examined compared to year 2003 and 2004 (Figure 1). In 2003 and 2004, a large number of infants screened weighed over 1750 grams but in 2005, only one of the infant screened weighed more than 1750 grams. The gestational age of the screened infants are shown in Figure 2. There was a steep rise in the number of cases who underwent ROP screening whose gestational age was 24 to 26 weeks.

    Table 2 shows the ROP screening findings for infants screened in 2003 to 2005. The number of cases screened had risen from 2003 to 2005. There was also an increase in the number of severe ROP cases (Stage 3 or worse) from 2003 to 2005. Of the 55 cases in whom ROP was detected, 50.9% (28/55) patients had Stage 1 or 2, 49.1% (27/55) patients had Stage 3 or worse (Table 2). A further look at the patients who had ROP showed that Stage 3 was found in 5/55 (9.1%) cases in 2003, 7/68 (10.3%) cases in 2004 and 15/65 (23.1%) cases in 2005 (Table 2). This difference was statistically significant.

    There was an increase in the number of babies weighing less than 751 grams who were admitted to the SCN comparing 2003 with 2005 (Figure 3), and the number of infants who survived to undergo ROP screening examination had also increased yearly from 2003 to 2005.

    A total of 27 patients from 55 patients with ROP (49.1%) required treatment, either diode laser photocoagulation or cryotherapy when the disease reached Threshold or Preª²threshold. The number of cases requiring treatment had shown a steady increase in numbers. In 2003 only 6/21 (19%) were treated, in 2004, 6/16 (37.5%) and 2005, 15/18 (83.3%) needed treatment (Table 3).

    There was a negative significant correlation between the number of examinations performed on the infant in SCN and birth weight. The smaller the birth weight the more times they needed to be examined. [Pearson correlation =ª²0.544, P=0.000, n=121] (Figure 4).

    The average number of examinations for each infant was 4.38¡À3.56 times (range 1 to 21 times) but when the infants were Figure 1Birth weight of infants from 2003 to 2005 in UMMC

    Figure 2Gestational age of infants from 2003 to 2005 in UMMC

    Figure 3Characteristics of infants with birth weight¡Ü750 grams admitted to SCN from 2003 to 2005

    Figure 4Scatter plot of cases showing birth weight and number of examinations

    Table 1Stage of ROP detected for infants from 2003 to 2005¡Às(range)

    nGestation/wkBirth weight/gTotal18829.2¡À2.5(23ª²38)1105¡À301(420ª²1920)No ROP13330.0¡À2.1(25ª²38)1197¡À272(420ª²1920)ROP detected5527.1¡À2.4(23ª²32)b883¡À247(432ª²1675)bStage 11628.4¡À2.1(25ª²32)1019.7¡À260.4(540ª²1675)Stage 21227.6¡À2.4 (25ª²32)892.8¡À214.0(625ª²1395)Stage 32426.3¡À2(23ª²32)833.5¡À206.5(600ª²1545)Zone 1325.3¡À2.3(24ª²28)512¡À128.3(432ª²610)

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