**5. Retinopathy of prematurity**

Retinopathy of prematurity (ROP) is a disease of premature babies. The disease is a potentially blinding disorder affecting primarily the retinas of the premature infants. Three epidemics of ROP have been described. The first one was seen in the 1950s in the industrialized countries. The reason was uncontrolled oxygen therapy and inadequate neonatal intensive care. With developing technology in the western countries, the incidence of the surviving extremely low birth weight babies increased. This increase in survival resulted in another epidemic. This epidemic of ROP was the second epidemic, which was characterized by extremely low birth weight babies with ROP. Currently there is an ongoing epidemic in the third world countries. The characteristics of this third epidemic are the mixture of the first and second epidemics (Gilbert, 2008).

#### **5.1 Risk factors and pathogenesis**

Uncontrolled oxygen therapy and premature birth are the most important risk factors for ROP. Babies born at or before 31 weeks of gestational age, or weighing 1500 grams or less are under high risk for ROP. Systemic problems associated with prematurity may also be considered to be independent risk factors. Sepsis, anemia and growth retardation are the most significant of these systemic associations.

The retina is not completely vascularized at birth. Especially the temporal quadrant of the retina lack blood vessels in the neonates and the retinal vessels development continues until the end of the first month of age. Vascular endothelial growth factor (VEGF) is very important for the retinal vasculature development. If uncontrolled and high oxygen therapy is applied in a premature infant, the production of VEGF may increase resulting in the development of ROP. Under physiological conditions, VEGF production is stimulated by hypoxia. Therefore, it is not exactly known why high oxygen levels lead to increased VEGF levels. The possible explanation for this inconsistency is the high variations encountered during uncontrolled oxygen supply. High oxygen levels suppress VEGF initially. This is followed by an exaggerated VEGF production, after cessation of the oxygen therapy. To prevent such variations in oxygen blood levels, oxygen supply should be given in a more steady level, according to the needs of the infants.

Pediatric Ophthalmology / Eye and Disorders 9

lower part of the canal at the level of the valve of Hasner, is not completely developed in some of the neonates. This developmental delay present in one fifth of the neonates. Spontaneous resolution of epiphora occurs in more than 90% of the cases within a year, after

Amniontocele (congenital dacryocele), punctual atresia or fistulae between the sac and the skin are other rare etiologies for epiphora. Amniotecele is characterized by a blue-green distention of the lacrimal sac, observed externally at the level of inner canthus. It is due to an imperforate valve of Hasner. Amniontocele is mostly self limiting within a few days of birth,

Spontaneous resolution is usual, so conservative treatments including antibiotic drops and massage of the lacrimal sac region is preferred within the first year of life. The index finger is put over the inner canthal region and the massage is applied firmly downwards. Three strokes of massage, 3-4 times per day are recommended. Early intervention is indicated if

Probing of the nasolacrimal canal under general anesthesia is performed if epiphora persists beyond the first year of age. Probing is performed to disrupt the obstructive membrane at the level of valve of Hasner mechanically. The success rate of probing is very high. If it fails, the probing can be repeated once more. If epiphora persists after 2 technically satisfactory probing, more invasive procedures, including silicon tubes implantation, balloon dilatation of the nasolacrimal duct or dacryocystorhinostomy should be considered (Rose, 2000).

Dacryocystorhinostomy is an invasive surgery, which involves anastomosing the lacrimal sac to the middle meatus by the removal of the lacrimal bone, is the gold standard treatment in adults, whereas it is usually the final treatment alternative in the pediatric age group.

The lens is a biconvex structure that hangs behind the iris. Its diameter is about 3.5 mm at birth and it grows to about 10 mm by adulthood. There are three structural elements that

completion of the lower end of the canal (Ballard, 2000).

**6.3 Management of congenital nasolacrimal duct obstruction** 

recurrent dacryocystitis occur before the first year of age.

**6.2 Differential diagnosis of epiphora in children** 

especially if massage is applied (Rose, 2000).

Fig. 2. Left dacryocele

**7. Childhood cataract** 
