TY - JOUR
T1 - In vivo measurement of regional variation in anterior scleral resistance to Schiotz indentation
AU - Patel, Hetal
AU - Gilmartin, Bernard
AU - Cubbidge, Robert P.
AU - Logan, Nicola S.
PY - 2011/9/1
Y1 - 2011/9/1
N2 - Recent studies indicate that ocular and scleral rigidity is pertinent to our understanding of glaucoma, age related macular degeneration and the development and pathogenesis of myopia. The principal method of measuring ocular rigidity is by extrapolation of data from corneal indentation tonometry (Ko) using Friedenwald's transformation algorithms. Using scleral indentation (Schiotz tonometry) we assess whether regional variations in resistance to indentation occur in vivo across the human anterior globe directly, with reference to the deflection of Schiotz scale readings. Methods: Data were collected from both eyes of 26 normal young adult subjects with a range of refractive error (mean spherical equivalent±S.D. of -1.77D±3.28D, range -10.56 to +4.38D). Schiotz tonometry (5.5g & 7.5g) was performed on the cornea and four scleral quadrants; supero-temporal (ST) and -nasal (SN), infero-temporal (IT) and -nasal (IN) approximately 8mm posterior to the limbus. Results: Values of Ko (mm3)-1 were consistent with those previously reported (mean 0.0101±0.0082, range 0.0019-0.0304). In regards to the sclera, significant differences (p<0.001) were found across quadrants with indentation readings for both loads between means for the cornea and ST; ST and SN; ST and IT, ST and IN. Mean (±S.D.) scale readings for 5.5g were: cornea 5.93±1.14, ST 8.05±1.58, IT 7.03±1.86, SN 6.25±1.10, IN 6.02±1.49; and 7.5g: cornea 9.26±1.27, ST 11.56±1.65, IT 10.31±1.74, SN 9.91± 1.20, IN 9.50±1.56. Conclusions: Significant regional variation was found in the resistance of the anterior sclera to indentation produced by the Schiotz tonometer.
AB - Recent studies indicate that ocular and scleral rigidity is pertinent to our understanding of glaucoma, age related macular degeneration and the development and pathogenesis of myopia. The principal method of measuring ocular rigidity is by extrapolation of data from corneal indentation tonometry (Ko) using Friedenwald's transformation algorithms. Using scleral indentation (Schiotz tonometry) we assess whether regional variations in resistance to indentation occur in vivo across the human anterior globe directly, with reference to the deflection of Schiotz scale readings. Methods: Data were collected from both eyes of 26 normal young adult subjects with a range of refractive error (mean spherical equivalent±S.D. of -1.77D±3.28D, range -10.56 to +4.38D). Schiotz tonometry (5.5g & 7.5g) was performed on the cornea and four scleral quadrants; supero-temporal (ST) and -nasal (SN), infero-temporal (IT) and -nasal (IN) approximately 8mm posterior to the limbus. Results: Values of Ko (mm3)-1 were consistent with those previously reported (mean 0.0101±0.0082, range 0.0019-0.0304). In regards to the sclera, significant differences (p<0.001) were found across quadrants with indentation readings for both loads between means for the cornea and ST; ST and SN; ST and IT, ST and IN. Mean (±S.D.) scale readings for 5.5g were: cornea 5.93±1.14, ST 8.05±1.58, IT 7.03±1.86, SN 6.25±1.10, IN 6.02±1.49; and 7.5g: cornea 9.26±1.27, ST 11.56±1.65, IT 10.31±1.74, SN 9.91± 1.20, IN 9.50±1.56. Conclusions: Significant regional variation was found in the resistance of the anterior sclera to indentation produced by the Schiotz tonometer.
KW - Ocular rigidity
KW - Schiotz tonometry
KW - Sclera
KW - Tissue resistance
UR - http://www.scopus.com/inward/record.url?scp=80051606285&partnerID=8YFLogxK
U2 - 10.1111/j.1475-1313.2011.00840.x
DO - 10.1111/j.1475-1313.2011.00840.x
M3 - Article
C2 - 21504438
AN - SCOPUS:80051606285
VL - 31
SP - 437
EP - 443
JO - Ophthalmic and Physiological Optics
JF - Ophthalmic and Physiological Optics
SN - 0275-5408
IS - 5
ER -
