Effects of Topical Treatment With β-Aminopropionitrile After Radial Keratotomy in the Rabbit

• This study assessed the effect of β-aminopropionitrile treatment on the long-term curvature and compliance of corneal tissue subjected to radial keratotomy (RK). β-Aminopropionitrile is known to inhibit cross-linking of collagen and is expected to enhance the flexibility of scar tissue, thereby reducing wound contracture and regression after RK. Seventeen adult New Zealand rabbits, weighing about 4.5 kg each, underwent RK in both eyes (eight incisions, 90% deep, 3-mm pupillary zone). Their mean preoperative corneal curvature was 44.25 diopters (±0.32D at 95% confidence level). Nine of the rabbits were treated topically with β-aminopropionitrile ointment (33 weitht% in petroleum three times daily), while the control group received the petrolatum base only. The remainder of the animals received bland petrolatum gel as a control. The animals were given periodic keratometric examinations and were killed after six to eight weeks. At that time, the β-aminopropionitrile group showed a mean reduction of 1.85 ±0.13 D in corneal curvature, compared with 1.18 ± 0.08 D in the control group. The compliance and strength of the corneas were measured in vitro immediately after death. In the pressure range from 10 to 40 mm Hg, the β-aminopropionitrile-treated corneas changed in curvature by an average of 1.4 D as compared with 0.5-D flattening for the controls. These results indicate the effectiveness of β-aminopropionitrile treatment in enhancing longterm compliance and reducing refractive regression after RK.