Editorial Type:
Ophthalmology

Association of height, body weight, age, and corneal diameter with calculated intraocular lens strength of adult horses

Meredith C. Mouney Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907.

Search for other papers by Meredith C. Mouney in
Current site
Google Scholar
PubMed Close
 DVM
,
Wendy M. Townsend Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907.

Search for other papers by Wendy M. Townsend in
Current site
Google Scholar
PubMed Close
 DVM, MS
, and
George E. Moore Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907.

Search for other papers by George E. Moore in
Current site
Google Scholar
PubMed Close
 DVM, PhD
DOI:
https://doi.org/10.2460/ajvr.73.12.1977
Volume/Issue:
Volume 73: Issue 12
Online Publication Date:
01 Dec 2012
Restricted access
Sign In Reprints and Permissions Purchase Article

Abstract

Objective—To determine whether differences exist in the calculated intraocular lens (IOL) strengths of a population of adult horses and to assess the association between calculated IOL strength and horse height, body weight, and age, and between calculated IOL strength and corneal diameter.

Animals—28 clinically normal adult horses (56 eyes).

Procedures—Axial globe lengths and anterior chamber depths were measured ultrasonographically. Corneal curvatures were determined with a modified photokeratometer and brightness-mode ultrasonographic images. Data were used in the Binkhorst equation to calculate the predicted IOL strength for each eye. The calculated IOL strengths were compared with a repeated-measures ANOVA. Corneal curvature values (photokeratometer vs brightness-mode ultrasonographic images) were compared with a paired t test. Coefficients of determination were used to measure associations.

Results—Calculated IOL strengths (range, 15.4 to 30.1 diopters) differed significantly among horses. There was a significant difference in the corneal curvatures as determined via the 2 methods. Weak associations were found between calculated IOL strength and horse height and between calculated IOL strength and vertical corneal diameter.

Conclusions and Clinical Relevance—Calculated IOL strength differed significantly among horses. Because only weak associations were detected between calculated IOL strength and horse height and vertical corneal diameter, these factors would not serve as reliable indicators for selection of the IOL strength for a specific horse.

Abstract

Objective—To determine whether differences exist in the calculated intraocular lens (IOL) strengths of a population of adult horses and to assess the association between calculated IOL strength and horse height, body weight, and age, and between calculated IOL strength and corneal diameter.

Animals—28 clinically normal adult horses (56 eyes).

Procedures—Axial globe lengths and anterior chamber depths were measured ultrasonographically. Corneal curvatures were determined with a modified photokeratometer and brightness-mode ultrasonographic images. Data were used in the Binkhorst equation to calculate the predicted IOL strength for each eye. The calculated IOL strengths were compared with a repeated-measures ANOVA. Corneal curvature values (photokeratometer vs brightness-mode ultrasonographic images) were compared with a paired t test. Coefficients of determination were used to measure associations.

Results—Calculated IOL strengths (range, 15.4 to 30.1 diopters) differed significantly among horses. There was a significant difference in the corneal curvatures as determined via the 2 methods. Weak associations were found between calculated IOL strength and horse height and between calculated IOL strength and vertical corneal diameter.

Conclusions and Clinical Relevance—Calculated IOL strength differed significantly among horses. Because only weak associations were detected between calculated IOL strength and horse height and vertical corneal diameter, these factors would not serve as reliable indicators for selection of the IOL strength for a specific horse.

Contributor Notes

Supported by Accutome.

Presented in abstract form at the 42nd Annual Meeting of the American College of Veterinary Ophthalmologists, Hilton Head, SC, October 2011.

Address correspondence to Dr. Townsend (townsenw@purdue.edu).
Cover American Journal of Veterinary Research
American Journal of Veterinary Research
Publication Date:
01 Dec 2012

  • 1. Gilger B, Davidson M, Howard P. Keratometry, ultrasonic biometry, and prediction of intraocular lens power in the feline eye. Am J Vet Res 1998;59:131–134.

    • Search Google Scholar
    • Export Citation

  • 2. Hillman JS. Intraocular lens power calculation for emmetropia: a clinical study. Br J Ophthalmol 1982;66:53–56.

  • 3. McMullen R, Gilger B. Keratometry, biometry, and prediction of intraocular lens power in the equine eye. Vet Ophthalmol 2006;9:357–360.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • 4. Farral H, Handscombe M. Follow-up report of a case of surgical aphakie with an analysis of equine visual function. Equine Vet J Suppl 1990;(10):91–93.

    • Search Google Scholar
    • Export Citation

  • 5. Millichamp NJ, Dziezyc J. Cataract phacofragmentation in horses. Vet Ophthalmol 2000;3:157–164.

  • 6. Dziezyc J, Millichamp NJ, Keller CB. Use of phacofragmentation for cataract removal in horses: 12 cases (1985–1989). J Am Vet Med Assoc 1991;198:1774–1778.

    • Search Google Scholar
    • Export Citation

  • 7. Whitley RD, Moore C, Slone D. Cataract surgery in the horse: a review. Equine Vet J Suppl 1983;(2):127–134.

  • 8. McMullen RJ, Davidson MG, Campbell NB, et alEvaluation of 30- and 25-diopter intraocular lens implants in equine eyes after surgical extraction of the lens. Am J Vet Res 2010;71:809–816.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • 9. Townsend WM, Jacobi S, Bartoe JT. Phacoemulsification and implantation of foldable +14 diopter intraocular lenses in five mature horses. Equine Vet J 2012;44:238–243.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • 10. Binkhorst CD. Power of the prepupillary pseudophakos. Br J Ophthalmol 1972;56:332–337.

  • 11. Retzlaff J. A new intraocular lens calculation formula. J Am Intraocul Implant Soc 1980;6:148–152.

  • 12. Gaiddon J, Bouhana N, Lallement P. Refraction by retinoscopy of normal, aphakic, and pseudophakic canine eyes: advantage of a 41-diopter intraocular lens? Vet Comp Ophthalmol 1996;6:121–124.

    • Search Google Scholar
    • Export Citation

  • 13. Grinninger P, Skalicky M, Nell B. Evaluation of healthy equine eyes by use of retinoscopy, keratometry, and ultrasonographic biometry. Am J Vet Res 2010;71:677–681.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • 14. Plummer CE, Ramsey DT, Hauptman JG. Assessment of corneal thickness, intraocular pressure, optical corneal diameter, and axial globe dimensions in Miniature Horses. Am J Vet Res 2003;64:661–665.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • 15. Townsend W, Wasserman N, Jacobi S, et alA pilot study on the corneal curvatures and ocular dimensions of horses less than one year of age (Published online ahead of print Jul 12, 2012). Equine Vet J doi:10.1111/j.2042–3306.2012.00598.

    • Search Google Scholar
    • Export Citation

  • 16. Rogers M, Cartee R & Miller W ea. Evaluation of the extirpated equine eye using B-mode ultrasonography. Vet Radiol 1986;24–29.

  • 17. Reef V. Ultrasonographic evaluation of small parts. In: Reef V, ed. Equine diagnostic ultrasound. Philadelphia: WB Saunders Co, 1998;481–547.

    • Search Google Scholar
    • Export Citation

  • 18. Davidson MG, Murphy CJ, Nasisse MP, et alRefractive state of aphakic and pseudophakic eyes of dogs. Am J Vet Res 1993;54:174–177.

  • 19. Schaeffel F, Howland HC. Corneal accommodation in chick and pigeon. J Comp Physiol A 1987;160:375–384.

  • 20. Gilger BC, Davidson MG, Colitz CM. Experimental implantation of posterior chamber prototype intraocular lenses for the feline eye. Am J Vet Res 1998;59:1339–1343.

    • Search Google Scholar
    • Export Citation

  • 21. Kubai MA, Bentley E, Miller PE, et alRefractive states of eyes and association between ametropia and breed in dogs. Am J Vet Res 2008;69:946–951.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • 22. Panchapakesan J, Mitchell P, Tumuluri K, et alFive year incidence of cataract surgery: the Blue Mountains Eye Study. Br J Ophthalmol 2003;87:168–172.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • 23. Murphy CJ, Zadnik K, Mannis MJ. Myopia and refractive error in dogs. Invest Ophthalmol Vis Sci 1992;33:2459–2463.

  • 24. Mitchell P, Hourihan F, Sandbach J, et alThe relationship between glaucoma and myopia: the Blue Mountains Eye Study. Ophthalmology 1999;106:2010–2015.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • 25. Koenig SB, Ruttum MS, Lewandowski MF, et alPseudophakia for traumatic cataracts in children. Ophthalmology 1993;100:1218–1224.

Advertisement