المحاضرة الاضافية الاخيرة

Retinopathy of prematurity (ROP) is a disease that affects immature vasculature in the eyes of premature babies. It can be mild with no visual defects, or it may become aggressive with new blood vessel formation (neovascularization) and progress to tractional retinal detachment and blindness.
Risk factors
Birth before 32 weeks' gestation, especially before 30 weeks
Birth weight of less than 1500 g, especially less than 1250 g
Possible risk factors include supplemental oxygen, hypoxemia and concurrent illness
Retinal vasculature begins to develop around 16 weeks' gestation. It grows circumferentially and becomes fully mature at term. Premature birth results in the cessation of normal retinal vascular maturation. Exposure of newborn premature infants to hyperoxia down regulates retinal vascular endothelial growth factor (VEGF). Blood vessels constrict and can become obliterated, resulting in delay of normal retinal vascular development. This hyperoxia-vasocessation is known as stage I of retinopathy of prematurity.
Early on, oxygen and nutrients can be delivered to the retina by means of diffusion from the underlying choroid capillary bed. The retina continues to grow in thickness and eventually outgrows its vascular supply. Over time, retinal hypoxia occurs and results in an overgrowth of vessels; this hypoxia-vasoproliferation is stage II of retinopathy of prematurity.
This process is mediated, in part, by VEGF and is affected by insulin-like growth factor-1 (IGF-1) and other cytokines. These changes in the retina result in retinopathy of prematurity ( new blood vessels formation and tractional retinal detachment)
Treatment: pan retinal photocoagulation and intra vitreal injection of anti VEGF in early stages (proliferative stage) and pars plana vitrectomy in advanced stages (tractional RD).
Regular screening should be done for all premature infants with low birth weight and supplement of O2 by fundoscopy to rule out the possibility of ROP.

Central Corneal thickness (CCT) should always be considered and adjusted for when measuring the IOP as an increased thickness results in IOP overestimation. On the contrary, decreased thickness leads to underestimation which is dangerous in certain eye diseases like Glaucoma. So, IOP should be adjusted according to CCT.

In the first steps of managing acute angle closure glaucoma, lower the IOP by using different medications for example Dorzolamide eye drops ( carbonic anhydrase inhibitor), Timolol (B bloker) and Brimonidine (α agonist) in addition to the frequent use of topical steroids.

Aflibercept (Eylea) : is a new anti VEGF drug used for treatment of diffused maculopathy and proliferative DR in diabetic patients.