Risk Factors for the Development of Asymmetric Retinopathy of Prematurity in Monozygotic Twins

Abstract

Abstract: : Purpose: Monozygotic twins are genetically identical yet asymmetry in the retinal presentation of retinopathy of prematurity(ROP) can occur. We sought to identify risk factors that might explain the cause for this asymmetry. Methods: We examined the charts of 3 sets of monozygotic(di-chorionic) twins for peri-natal and post natal data. These included: APGAR scores, FiO2%, PEEP and respiratory rates, blood gases, hematological and chemical serum indicies as well as the clinical course. Results: All neonates required diode laser retinal treatment for zone 2 stage 3 plus disease. In each set of twins one eye stabilized while the other eye progressed to stage 4 ROP requiring vitrectomy, lensectomy and scleral buckle. All tested parameters were identical except for serum potassium elevations to 7.2 mEq/L in stage 4 ROP eyes vs 4.1 mEq/L in stage 3 ROP. Also O₂ saturations > 95%(average) were noted in stage 4 ROP eyes vs 83% in stage 3 ROP eyes. Conclusions: Serum potassium elevations and O₂ saturations >95% were noted in one of a set of twins whose ROP progressed from stage 3 ROP to stage 4 ROP. No other peri-natal risk factors were found to explain the asymmetrical course of ROP in monozygotic twins.

Keywords: retinopathy of prematurity • clinical (human) or epidemiologic studies: ris