Through the first two years, the visual acuity remained about the same in the two groups ( results published in 2011). At seven years, visual acuity on average remained stable in the systemic group but declined about six letters in the implant group. The researchers found that implant-treated eyes had reactivations of uveitis after about five years, which coincided with a decline in visual acuity. The loss of vision in the implant group appears to have been due to increased damage in the retina and choroid (a tissue rich in blood vessels lying underneath the retina).
Five trials comparing inhaled versus systemic corticosteroids in treatment of CLD were identified. Two trials ( Dimitriou 1997 ; Nicholl 2002 ) were excluded as both included non-ventilator dependent patients and the groups of ventilated infants could not be identified separately. Three trials fulfilled the inclusion criteria and are included in this updated review: Halliday et al ( Halliday 2001 ), Suchomski et al ( Suchomski 2002 ) and Rozycki et al ( Rozycki 2003 ) (published since our initial review). Even though Rozycki et al ( Rozycki 2003 ) enrolled preterm infants with birth weights between 650 to 2, 000 g, on review of the published data, 93% of the subjects enrolled had birth weights < 1, 000 g with PMA ranging from 23 to 31 weeks. Therefore, the data from this trial are included in this review. Each of these trials have been published as a full text article. Details of each trial are given in the table 'Characteristics of Included Studies'.
Corticosteroids have been used as drug treatment for some time. Lewis Sarett of Merck & Co. was the first to synthesize cortisone, using a complicated 36-step process that started with deoxycholic acid, which was extracted from ox bile .  The low efficiency of converting deoxycholic acid into cortisone led to a cost of US $200 per gram. Russell Marker , at Syntex , discovered a much cheaper and more convenient starting material, diosgenin from wild Mexican yams . His conversion of diosgenin into progesterone by a four-step process now known as Marker degradation was an important step in mass production of all steroidal hormones, including cortisone and chemicals used in hormonal contraception .  In 1952, . Peterson and . Murray of Upjohn developed a process that used Rhizopus mold to oxidize progesterone into a compound that was readily converted to cortisone.  The ability to cheaply synthesize large quantities of cortisone from the diosgenin in yams resulted in a rapid drop in price to US $6 per gram, falling to $ per gram by 1980. Percy Julian's research also aided progress in the field.  The exact nature of cortisone's anti-inflammatory action remained a mystery for years after, however, until the leukocyte adhesion cascade and the role of phospholipase A2 in the production of prostaglandins and leukotrienes was fully understood in the early 1980s.