Retinal microvascular development in the first two years.

The link between in utero and early life insults and the development of chronic illness remains to be fully understood, but there is increasing data to indicate that microvasculature pathology plays an important mechanistic role. Currently available data indicate that retinal microvasculature changes are detectable in children as young as six years of age, however, there are no data for younger children. We present retinal microvasculature measurement from the first two years of life. Retinal images suitable for analysis were available from 18 infants in our proof-of-concept study. The mean and standard deviation (SD) for birth weight and gestation was 3410 (384) g and 39.1(1.4) weeks, respectively. Retinal vessel calibres were summarized as the mean(SD) central retinal arteriolar equivalent (CRAE) at six months of age was 156 (32) µm, increased to 175 (75) µm by 12 months and a slightly declined by 24 months of age to 168 (50) µm. In a similar pattern, mean(SD) central retinal venular equivalent (CRVE) at six months was 211 (19) µm, increased to 238 (25) µm by 12 months of age followed by a slight decline at 24 months of age to 222 (36) µm. The arterio-venous ratio and tortuosity index remained the same at 6, 12 and 24 months. Findings from this study could help future investigators better understand early microvasculature changes and adaptation that occur early in life.

Use of digital retinal imaging in screening for retinopathy of prematurity.

The frequency of premature births is increasing world-wide. This factor, combined with improved survival and revised screening criteria, is resulting in an increased workload in screening for retinopathy of prematurity. Digital retinal imaging is emerging as an important alternative tool for diagnosing retinopathy of prematurity, and its use has even been extended to developing countries. Neonatal nurses and technicians can be trained to use digital imaging devices effectively. This is important in areas that do not have ready access to paediatric ophthalmologists. The ability to transfer images electronically makes it a valuable tool in telemedicine, while the ability to store and retrieve images is also advantageous from a medico-legal perspective. Image analysis software can further improve the accuracy of diagnosis. The main limitation of this technology is its high capital cost.

The lack of association between vascular endothelial growth factor and retinopathy of prematurity in an observational study.

PURPOSE: The objective of this study was to investigate the association between prematurity, vascular endothelial growth factor A (VEGF-A), VEGFR-1 (soluble fms-like tyrosine kinase-1 (sFLT-1)) and retinopathy of prematurity (ROP). METHODS: A cohort of 53 neonates (gestation <28 weeks) was recruited into this study and peripheral venous samples for VEGF and sFLT-1 measurement were obtained between gestational ages 320-326 weeks. RESULTS: The mean birth weight for the preterm neonates was 850 (178) g and the median gestational age was 26.4 [24.7-27.4] weeks. The median VEGF-A level was 1348 [608-2216] pg/mL and the median sFLT-1 level was 178 [103-244] pg/mL. Thirty-three neonates (33/53) developed various stages of ROP during their stay in the neonatal unit but only five neonates developed severe (stage 3) ROP needing treatment. The neonates with ROP were smaller (birth weight 801 (111) vs. 990 (175) g; p < .0001), more preterm (gestation 25.4 [24.2-26.0] vs. 27.1 [26.8-27.9] weeks; p < .0001) and received supplemental oxygen for a longer duration (1140 [218-1813] vs. 04 [40-434] hours; p= .012). There was no statistically significant difference in the VEGF-A level or sFLT-1 levels between those who developed ROP and those who did not. There was a positive correlation between VEGF and both birth weight and gestation, respectively. There was no correlation between sFLT1 and birth weight or gestation. VEGF-A/sFLT-1 ratio in babies treated for ROP was significantly lower compared to those not treated (2.8 [1.0-5.7] vs. 9.9 [5.6-13.7]; p = .04). A logistic regression model identified gestational age to be a statistically significant predictor of ROP (odds ratio 0.03 (0.001-0.550); p = .019). CONCLUSIONS: There is no direct correlation between systemic VEGF-A or sFLT-1 plasma levels and severity of ROP in extremely preterm neonates. The link between VEGF and ROP remains to be fully understood.

The association between systemic vascular endothelial growth factor and retinopathy of prematurity in premature infants: a systematic review.

Retinopathy of prematurity (ROP), a vasoproliferative disorder exclusive to premature infants is an important cause of childhood blindness. The number of premature infants surviving with this condition is expected to increase globally. Animal models of oxygen-induced retinopathy studies have shown vascular endothelial growth factor (VEGF) to be a key player in the pathogenesis of ROP. This has led to increased use of VEGF antagonist as an alternative treatment for ROP. The purpose of this systematic review is to determine the association between VEGF and ROP in human newborn. The literature review identified 12 studies to date which fulfilled the search criteria. Investigators used cord blood, serum, plasma and tissue samples to investigate the association between ROP and VEGF. Studies that measured VEGF in cord blood found mixed results, with low VEGF (at birth) associated with ROP in one study and no difference noted in two others. Mixed results were also seen in studies determining VEGF in postnatal venous samples. Four studies showed no difference in VEGF level between premature infants with and without ROP, one study showed an increased VEGF level in premature infants with ROP and another study found serum VEGF to be low in premature infants with ROP. The most recent study demonstrated an initial increase in serum VEGF followed by a decline at the time of treatment. These contradictory results indicate that we are yet to fully understand the role of VEGF in human premature infants and question the rationale of treating ROP with anti-VEGF. Anti-VEGF therapy results in systemic effect on serum VEGF levels for up to 2 months and this could have an effect on neurodevelopmental outcome. The effect of this on other developing organs is currently unknown. More studies are required to determine the mechanistic relationships between systemic VEGF and ROP in premature infants.

Optic disc measurements in full term infants.

BACKGROUND: The objectives of this study were to measure optic disc size in full term infants and to determine whether this value is influenced by sex or birth weight. METHODS: Retinal images from a cohort of full term infants admitted to a tertiary perinatal centre were obtained using a retinal camera. Optic disc size was measured by carefully delineating the outline with a cursor using image analysis software. MEDLINE was then systematically searched to compare the data with other published articles. RESULTS: 35 images of left and right eyes from 35 infants were assessed. An image from one eye per patient was then chosen for analysis. The following results were found: mean birth weight 3050±706 g; mean gestation 38.9±1.4 weeks. Mean optic disc area was 1.26±0.23 mm(2); mean vertical diameter was 1.37±0.15 mm; and mean horizontal diameter was 1.14±0.12 mm. The vertical diameter of the optic disc was significantly longer than the horizontal diameter (p<0.0001). CONCLUSION: Birth weight and sex did not influence the size of the optic disc in term infants. There were no differences in optic disc measurements between male and female infants and between low birth weight and normal birth weight infants.

Pain relief for premature infants during ophthalmology assessment.

BACKGROUND: The ophthalmological examination of premature infants, which is essential for the detection of retinopathy of prematurity (ROP), can be painful and distressing for the infant. Various researchers have investigated the benefits of topical anesthesia, oral sucrose, and non pharmacological intervention for pain relief. The purpose of this study is to review the current state of knowledge on the effectiveness of these approaches. METHODS: A literature search was performed with MEDLINE (January 1980 to January 2011) and the Cochrane Central Register of Controlled Trials, Issue 1 of 4 (January 2011), to determine the currently available evidence on methods of pain relief for premature infants undergoing ROP examination. RESULTS: Most studies supported the use of topical proparacaine, which marginally decreased pain without any side effects. Oral sucrose did not significantly reduce pain scores during ROP examinations, and withholding feeding before the examination was not beneficial. Infants given pacifiers had lower pain scores than those without pacifiers, and infants who were nested experienced less distress during and after the procedure. Conflicting data existed on the benefits of different examination techniques, but the insertion of a lid speculum appeared to be the most uncomfortable aspect of the screening examination. CONCLUSIONS: Topical anesthetics marginally reduce pain during eye examination in premature infants. Contrary to standard practice, it appears that patients are more comfortable if they are fed before the examination, and there is no benefit of oral sucrose. Nonpharmacological interventions, including sucking on a pacifier and nesting, may also be beneficial.

A survey of ocular therapeutic pharmaceutical agents in optometric practice.

BACKGROUND: In all Australian states optometrists are permitted to use diagnostic topical ocular drugs in the practice of their profession. In addition, legislation has just been passed in Victoria allowing optometrists to prescribe topical S4 medications for ocular conditions. Changing optometric legislation to incorporate S4 ophthalmic agents is a topical issue within optometry. METHODS: By postal survey, we asked Queensland optometrists to gauge their level of education, current mode of practice and whether they were in favour of gaining access to prescription-only therapeutic medications. Their opinions on the education requirements, perceived potential public benefits and the possible barriers to optometrists gaining prescribing rights to therapeutic agents were also investigated. RESULTS: A 45 per cent response rate to the survey (231 responses out of 517) was obtained. The majority of respondents (88 per cent) wanted to be able to prescribe therapeutic agents. Over 50 per cent considered themselves competent and believed they were capable of treating dry eye, blepharitis, allergic conjunctivitis, corneal abrasions and contact lens induced papillary conjunctivitis. Over 90 per cent would be confident recommending topical lubricants and antihistamines, while 65 per cent felt they were adequately prepared to prescribe topical antibiotics. Education level, in particular the completion of a therapeutic drugs course, was the main factor that determined whether the respondents practised or were willing to practise at a higher level. CONCLUSION: The majority of Queensland optometrists are well aware of the issues surrounding the use of pharmaceutical agents. Many optometrists feel they are well prepared for prescribing ocular therapeutic agents.