Porcine sclera: thickness and surface area.
OBJECTIVE
To assess the thickness and surface area of porcine sclera.


METHODS
One hundred twenty-eight porcine globes were sectioned from the center of the cornea to the region of the optic nerve. Photographs of the sectioned sclera including a millimeter scale were taken. Photographic slides were projected onto blank paper, and the scleral silhouette was traced. Perpendicular thickness measurements were taken at 1-mm intervals from the limbus to the optic nerve. The sclera of 18 porcine eyes were cut into small pieces, and the surface area was calculated with computerized digital tracing software.


RESULTS
The scleral thickness near the corneal scleral limbus was 0.83 +/- 0.2, 0.91 +/- 0.17, and 1.12 +/- 0.23 mm in the small-, medium-, and large-sized pigs, respectively. Thickness decreased to minimum of 0.31 +/- 0.07, 0.35 +/- 0.1, and 0.43 +/- 0.16 mm at a distance of 5 mm from the limbus in the small- and medium-sized pigs and 6 mm in the large-sized pigs, respectively. The mean scleral surface area was 7.78 +/- 0.66, 9.66 +/- 0.75, and 11.92 +/- 1.57 cm(2) in the small-, medium-, and large-sized pigs, whereas the corneal surface area was 1.09 +/- 0.07, 1.15 +/- 0.09, and 1.40 +/- 0.19 cm(2), respectively.


CONCLUSIONS
Porcine scleral thickness is very similar to human scleral thickness. The porcine model is an excellent model for studying transscleral drug delivery.
Olsen
Timothy W
TW
Department of Ophthalmology, University of Minnesota, Minneapolis, Minnesota 55455, USA. olsen010@tc.umn.edu
Sanderson
Scott
S
Feng
Xiao
X
Hubbard
William C
WC
D000818:Animals; D000886:Anthropometry; D007091:Image Processing, Computer-Assisted; D012590:Sclera / Q000033:anatomy & histology*; D013552:Swine / Q000033:anatomy & histology*