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Veluchamy A. Barathi, Daphne C. Han, Candice E. Ho, Pradeep P. Panengad, Roger W. Beuerman; Scleral Cross-Linking Retards Axial Length Growth In The Rabbit Eye. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3467.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the potential of glyceraldehyde (GA) in arresting the progression of ocular axial elongation in rabbits.
Ten rabbits were treated with subtenon injections of 0.10mL 0.01% GA dissolved in Viscoat at four different meridians at two different time points, i.e. at post-natal age of 4 weeks and 8 weeks. The rabbits were treated unilaterally, with the untreated eye serving as contra-lateral control, and two rabbits were treated with saline as a vehicle control. Primary outcomes such as axial length and corneal curvature measurements with A-scan ultrasound and refraction with an autorefractor were performed weekly. In addition, intraocular pressure (IOP) was measured weekly using Tonopen, and ocular tissues obtained for stress-strain function and histology. Four untreated rabbits served as controls. Outcome measures were compared between the treated and untreated eyes, and to controls. Results were analyzed with T-test for statistical significance.
Axial growth in the untreated eyes were linearly increasing about 140μm±0.08 (mean ± S.D, n=10 eyes, p=0.001) per week and only 12±0.02μm (p=0.04) increase was found in GA treated eyes per week. The axial growth difference between the GA treated and untreated eyes were -350μm ± 0.07 (mean ± S.D, n=10 eyes, p=0.003) 4 weeks post-treatment. The axial growth difference between the GA treated and untreated eyes were further reduced about -656μm ± 0.06 (mean ± S.D, n=10 eyes, p=0.001) in the second injected group 3weeks after treatment. The GA-treated eyes were slightly more hyperopic than the untreated eyes (3.6±0.18D and 3.1±0.11D respectively, n=10 eyes, p=0.07). No significant difference found in the corneal curvature and IOP measurements. Histopathological examination determined that there was no change in the ocular structure or toxicity found in the sclera and conjunctiva. In addition, mechanical test studies show that GA increased the strength of scleral strips by about 6 folds over the vehicle control.
These results confirm that subtenon injections of GA significantly reduced the axial length elongation of the rabbit eye. They prove positive in retarding axial length growth without any toxic effects to the ocular tissue. This is the first study on the effect of scleral crosslinking on the axial length growth of the animal eye.
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