Neonatal retinal and vitreous hemorrhages are mostly influenced by the modalities of delivery [18]. In fact, caesarean delivery is associated with a higher incidence of retinal and vitreous hemorrhages. Other main parameters correlate with retinal and vitreous hemorrhages are gestational age, birth weight, asphyxia, scalp hematoma and precipitate labour [19]. Newborn retinal hemorrhages are commonly bilateral, predominantly intraretinal and in the posterior pole [20]. In our case, the patient was born by eutocic vaginal delivery and presented no reported risk factor.
Other etiologies associated with vitreous hemorrhages in pediatric age group are separated in traumatic and nontraumatic causes. Nontraumatic causes are, in order of frequency, retinoblastoma, Terson’s syndrome, persistent fetal vasculature, idiopathic, regressed retinopathy of prematurity, familial exudative vitreoretinopathy, intermediate uveitis, associated with lymphoblastic leukemia, retinitis pigmentosa, familial retinal artery macroaneuvrysm, nanophtalmos, neonatal meningitis, panuveitis (brucellosis), Stickler diseases with rhegmatogenous retinal detachment (RRD), arteriovenous malformation, Coats disease and Marfan syndrome with RRD [21]. Coagulation disorders could also be implied, including leukemia, haemophilia, Von Willebrand disease and Protein C deficiency [22]. In our case, an isolated transient polycythemia was found, and no recent traumatic history or vitreoretinal diseases were associated.
After excluding an inherent disease, a postoperative complication of the non-penetrating deep sclerectomy was suspected. Common complications of non-penetrating deep sclerectomy include transient hyphema, shallows and flats in the anterior chamber, hypotonia or hypertonia, bleb fibrosis, and more rarely, choroidal effusion, detachment or hemorrhage, macular edema and decompression retinopathy [23].
We hypothesized that the underlying mechanism involves a decompression retinopathy. In fact, post-operative abrupt hypotonia leads to rapid increase in central retinal artery flow, increasing retinal capillary perfusion pressure beyond its autoregulatory capacity, resulting in hemorrhages [24]. Thus, the extravasated blood may sediment under the posterior hyaloid membrane [25]. The main differential diagnosis for decompression retinopathy includes venous occlusion and Valsalva’s retinopathy. Venous occlusion was excluded due to the lack of venous dilatation, peripheral retinal hemorrhages and optic disc edema. Similarly, the possibility of Valsalva’s retinopathy was remote because the patient had no incident of coughing or sneezing postoperatively.
The incidence of decompression retinopathy in children has been evaluated at 5.2% in a recent study [26], slightly higher than the 3.0% reported by Jung et al. in adult population. According to the current vascular and mechanical theories for the pathophysiology of decompression retinopathy, the lower degree of resistance in the child sclera may explain this higher incidence. Therefore, mechanical deformation of the posterior segment structures, including posterior cortical vitreous, retinal capillaries and lamina cribrosa might be intensified [27].
In pediatric population, the specific high density of the collagen fibrils meshwork with interspersed extensive arrays of long hyaluronan molecules explains the slower clearance of vitreous hemorrhage, compared with adults [28]. Miller-Mecks et al. demonstrated that visual axis obstruction induced by vitreous hemorrhage may engender high myopia [29], persisting after vitreous clarity recovery, which contributes to the onset of an amblyopia [30]. Our case report is in agreement with Miller-Mecks observation, as high myopia developed in the right eye requiring refractive correction. It is a challenge to determine until when vitrectomy can be delayed. Ferrone et al. suggested that vitreous hemorrhage sequelae are potential from five weeks, supporting a prompt treatment strategy [31]. In our case, pars plana vitrectomy was performed at the age of 4 weeks. Given the surgical difficulty and the extremely high risk of serious postoperative complications, such procedure should not be generalised.
To minimize the risk of decompression retinopathy, several measures should be considered: optimized control of the IOP before glaucoma surgery, performing a paracentesis to allow slow drainage of aqueous humor, use of viscoelastic material in anterior chamber to allow progressive lowering of IOP, and tight and releasable sutures of the scleral flap to prevent marked and prolonged hypotonia [26].
Non-penetrating deep sclerectomy is an effective procedure in congenital glaucoma and is considered theoretically safer than trabeculectomy [32]. In this case report, we described a child with primary congenital glaucoma who developed pre-macular subhyaloid hemorrhage after non-penetrating deep sclerectomy, as the only manifestation of a decompression retinopathy. To our knowledge, this is the first report of such complication occurring after non-penetrating deep sclerectomy for primary congenital glaucoma and requiring vitrectomy. This uncommon complication needs to be considered as it is a potential cause of organic amblyopia.
Patient consent
The patient could not give consent. The parents gave verbal and written permission. This report does not contain any personal information that could lead to the identification of the patient.