How does ROP develop?

Retinopathy of prematurity can develop when babies are born before their retinal blood vessels are fully formed

Classifying retinopathy of prematurity

Knowing how to classify retinopathy of prematurity is essential as it provides information on the prognosis and guides decision making about screening and treatment

Abnormal Complement Activation and Inflammation in the Pathogenesis of Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a neurovascular complication in preterm babies, leading to severe visual impairment, but the underlying mechanisms are yet unclear. The present study aimed at unraveling the molecular mechanisms underlying the pathogenesis of ROP. A comprehensive screening of candidate genes in preterms with ROP (n = 189) and no-ROP (n = 167) was undertaken to identify variants conferring disease susceptibility. Allele and genotype frequencies, linkage disequilibrium and haplotypes were analyzed to identify the ROP-associated variants. Variants in CFH (p = 2.94 x 10(-7)), CFB (p = 1.71 x 10(-5)), FBLN5 (p = 9.2 x 10(-4)), CETP (p = 2.99 x 10(-5)), and CXCR4 (p = 1.32 x 10(-8)) genes exhibited significant associations with ROP. Further, a quantitative assessment of 27 candidate proteins and cytokines in the vitreous and tear samples of babies with severe ROP (n = 30) and congenital cataract (n = 30) was undertaken by multiplex bead arrays and further validated by western blotting and zymography. Significant elevation and activation of MMP9 (p = 0.038), CFH (p = 2.24 x 10(-5)), C3 (p = 0.05), C4 (p = 0.001), IL-1ra (p = 0.0019), vascular endothelial growth factor (VEGF) (p = 0.0027), and G-CSF (p = 0.0099) proteins were observed in the vitreous of ROP babies suggesting an increased inflammation under hypoxic condition. Along with inflammatory markers, activated macrophage/microglia were also detected in the vitreous of ROP babies that secreted complement component C3, VEGF, IL-1ra, and MMP-9 under hypoxic stress in a cell culture model. Increased expression of the inflammatory markers like the IL-1ra (p = 0.014), MMP2 (p = 0.0085), and MMP-9 (p = 0.03) in the tears of babies at different stages of ROP further demonstrated their potential role in disease progression. Based on these findings, we conclude that increased complement activation in the retina/vitreous in turn activated microglia leading to increased inflammation. A quantitative assessment of inflammatory markers in tears could help in early prediction of ROP progression and facilitate effective management of the disease, thereby preventing visual impairment

Avascular Peripheral Retina in Infants

Avascular peripheral retina in an infant is a common characteristic of numerous pediatric retinal vascular disorders and often presents a diagnostic challenge to the clinician. In this review, key features of each disease in the differential diagnosis, from retinopathy of prematurity, familial exudative vitreoretinopathy, Coats disease, incontinentia pigmenti, Norrie disease, and persistent fetal vasculature, to other rare hematologic conditions and telomere disorders, will be discussed by expert ophthalmologists in the field

NMNAT1 Mutations Cause Leber Congenital Amaurosis

Leber congenital amaurosis (LCA) is an infantile-onset form of inherited retinal degeneration characterized by severe vision loss. Two-thirds of LCA cases are caused by mutations in 17 known disease genes (RetNet Retinal Information Network). Using exome sequencing, we identified a homozygous missense mutation (c.25G>A, p.Val9Met) in NMNAT1 as likely disease-causing in two siblings of a consanguineous Pakistani kindred affected by LCA. This mutation segregated with disease in their kindred, including in three other children with LCA. NMNAT1 resides in the previously identified LCA9 locus and encodes the nuclear isoform of nicotinamide mononucleotide adenylyltransferase, a rate-limiting enzyme in nicotinamide adenine dinucleotide $(NAD^+)$ biosynthesis. Functional studies showed the p.Val9Met mutation decreased NMNAT1 enzyme activity. Sequencing NMNAT1 in 284 unrelated LCA families identified 14 rare mutations in 13 additional affected individuals. These results are the first to link an NMNAT isoform to disease and indicate that NMNAT1 mutations cause LCA

Retinal Detachment

Detachment of the retina is a serious event, which may result in complete blindness. The outer segments of the photoreceptors receive oxygen and nutrition from the choroid. If the retina is detached from the choroid, the photoreceptors will fail. The fovea has no retinal blood vessels and depends wholly on the choroid for its oxygen, so detachment of the macula leads to permanent damage to the cones and rods at the posterior pole, and loss of vision. If the macula is not detached, then good vision can be retained if the retina is re-attached promptly

Acute postoperative endophthalmitis by <i> Gemella haemolysans</i>

Endophthalmitis is a rare and serious post-surgical complication. We report a case of acute postoperative endophthalmitis after an uneventful cataract surgery caused by a commensal organism, <i>Gemella haemolysans</i>. The patient was successfully treated with vitrectomy and intravitreal antibiotics like vancomycin, along with topical cefazolin

Intraocular osseous metaplasia. A clinico-pathological study

Purpose: To evaluate the clinico-pathologic features of intraocular osseous metaplasia. Methods: Pathology specimens of enucleated eyes submitted to the ophthalmic pathology service at a tertiary eye-care referral center between January 1995 and June 1999 were studied for intraocular osseous metaplasia. Specific histopathologic features noted in specimens with osseous metaplasia were the presence of retinal detachment, gliosis, retinal pigment epithelial hyperplasia, drusen, epiretinal membrane, fibrovascular proliferation and inflammation. Immunohistochemistry using monoclonal antibody against glial fibrillary acidic protein was performed to assess the glial component within the membranes and the proliferative vitreoretinal mass. Clinical records were reviewed and correlated with histopathologic findings. Results: Osseous metaplasiaS was noted in 8 of 151 (5.2&#x0025;) eyes examined. Clinical diagnosis in these was phthisis bulbi, staphyloma, absolute glaucoma and microphthalmos. Enucleation was performed for relief of symptoms (in painful blind eyes) or for cosmesis, and in an eye inciting sympathetic ophthalmia. Retinal detachment, gliosis and retinal pigment epithelial hyperplasia were noted in all the cases. Drusen with calcification or ossification (5 of 8), fibrovascular proliferation in the vitreous (5 of 8) and active inflammation (4 of 8) were the other associated histologic features. Location of ossification was subretinal in 3 cases, preretinal (ora serrata) in 1 case and in both locations in 4 cases. The eyes with subretinal osseous metaplasia had associated calcified drusen, while preretinal ossification was seen within the fibrovascular membranes. Conclusion: Chronic retinal detachment, hyperplasia and transdifferentiation of retinal pigment epithelium appear to be a few of the prerequisites for intraocular osseous metaplasia. Ossification can occur at isolated subretinal and preretinal locations or can involve both. Though a larger study is required to postulate the chronology of events, in this small series, isolated subretinal ossification appears to be initiated by calcification and ossification of drusen, while in the pre-retinal region it is associated with vitreoretinal proliferation