Phosphodiesterase type 5 inhibitors, visual changes, and nonarteritic anterior ischemic optic neuropathy: Is there a link?

Ophthalmic findings in neonates receiving sildenafil

AIM

To determine the risk of ocular complications of sildenafil therapy in neonates.

METHODS

Retrospective case review of neonates with persistent pulmonary hypertension of the newborn who received sildenafil therapy between 2010 and 2015 in a single, tertiary surgical neonatal intensive care unit in Australia. Ophthalmic examination findings in the neonatal intensive care unit and follow-up were examined.

RESULTS

Twenty-seven neonates with persistent pulmonary hypertension of the newborn received sildenafil. The median gestational age (GA) was 38 weeks (range 24-41 weeks), and median birthweight was 2690 g (range 454-4270 g). Ophthalmic review was undertaken in 23 neonates, and 16 neonates were term or near-term infants (GA 31-40 weeks). All of them had a normal initial ophthalmic examination; one child was later diagnosed with hypermetropia and another with infantile esotropia. Amongst the seven premature infants (GA 24-30 weeks), three had retinopathy of prematurity (ROP) diagnosed at the first ophthalmic review and the other four had normal initial examinations. Two patients later developed ROP, one of whom was also diagnosed with congenital motor nystagmus. All five patients diagnosed with ROP were extremely preterm (<28 weeks) with low birthweight (454-635 g).

CONCLUSIONS

There were no short-term complications attributable to sildenafil therapy identified in term or near-term neonates (GA ≥31 weeks). This cohort of neonates does not typically undergo ophthalmic review as part of the ROP screening protocol in our institution. Routine ophthalmic review of neonates on sildenafil therapy, who are not at risk of ROP, is therefore unlikely to be warranted. Further research is required to clarify the relationship between sildenafil and ROP.

Sildenafil attenuates vaso-obliteration and neovascularization in a mouse model of retinopathy of prematurity

PURPOSE

We sought to determine the effect of sildenafil on retinal vascular changes in a mouse model of oxygen-induced retinopathy (OIR).

METHODS

Vascular defects in OIR mice were quantified by measuring vaso-obliteration at postnatal days 12 and 17 (P12 and P17) and neovascularization at P17 to compare sildenafil-treated to dextrose-treated OIR mice. Retinal HIF1α protein expression was quantified by Western blotting and normalized to that of β-actin. Right ventricular hypertrophy was measured by Fulton's index as a surrogate for hyperoxia-induced pulmonary hypertension.

RESULTS

At P12, OIR mice treated with sildenafil demonstrated a 24% reduction in vaso-obliteration (P < 0.05), whereas at P17, treated animals showed a 50% reduction in neovascularization (P < 0.05) compared to dextrose-treated controls. Sildenafil-treated OIR mice had stabilization of retinal HIF1α at P12, immediately after hyperoxia. At P17, sildenafil-treated OIR mice had decreased HIF1α relative to untreated mice. OIR mice developed right ventricle hypertrophy that was significant compared to that in room air controls, which was abrogated by sildenafil.

CONCLUSIONS

Sildenafil treatment significantly decreased retinal vaso-obliteration and neovascularization in a mouse OIR model. These effects are likely due to sildenafil-induced HIF1α stabilization during hyperoxia exposure. Furthermore, we confirm disease overlap by showing that OIR mice also develop hyperoxia-induced right ventricular hypertrophy, which is prevented by sildenafil. This study is a first step toward delineating a potential therapeutic role for sildenafil in OIR and further suggests that there may be common pathophysiologic mechanisms underlying hyperoxia-induced retinal and pulmonary vascular disease.

The effect of sildenafil on retinopathy of prematurity in very preterm infants

OBJECTIVE

Sildenafil is occasionally used as rescue treatment for preterm infants with severe bronchopulmonary dysplasia and pulmonary arterial hypertension. In adults, sildenafil treatment has been associated with several ophthalmological adverse effects, including nonarteritic ischaemic optic neuropathy. We reviewed the effect of sildenafil on retinopathy of prematurity (ROP) in very preterm infants.

STUDY DESIGN

Retrospective case-control study. Infants born <30 weeks gestation who had received sildenafil during their hospitalisation were included. A control group matched for gestation, birth weight, gender, and place of birth was identified from the departmental database. For every sildenafil case, three matched controls were studied. Baseline data, sildenafil therapy data, results of eye examinations and respiratory data were analysed.

RESULT

17 infants received sildenafil between 2004 and 2010. The median duration of sildenafil treatment was 52 days. Baseline characteristics were similar between groups. The odds ratio for an increase in ROP stage in the group treated with sildenafil was 1.35 (95% confidence interval 0.39-4.62, P-value 0.63). One infant in each group required laser treatment.

CONCLUSION

Sildenafil treatment did not affect ROP progression or increase the need for laser treatment in this cohort.