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Home / Equine Research Bank / BMC Vet Res / Intraocular lens power calculation for the equine eye.
BMC veterinary research2018; 14(1); 123; doi: 10.1186/s12917-018-1448-6

Intraocular lens power calculation for the equine eye.

Abstract: Phacoemulsification and intraocular lens (IOL) implantation during cataract surgery in horses occur with increasing frequency. To reduce the postoperative refractive error it is necessary to determine the proper IOL power. In the present study retinoscopy, keratometry and ultrasonographic biometry were performed on 98 healthy equine eyes from 49 horses. The refractive state, corneal curvature (keratometry) and the axial location of all optical interfaces (biometry) were measured. The influences of breed, height at the withers, gender and age on values obtained and the comparison between the left and right eye were evaluated statistically. Corresponding IOL power were calculated by use of Binkhorst and Retzlaff theoretical formulas. Results: Mean ± SD refractive state of the horses was + 0.32 ± 0.66 D. Averaged corneal curvature for Haflinger, Friesian, Pony, Shetland pony and Warmblood were 21.30 ± 0.56 D, 20.02 ± 0.60 D, 22.61 ± 1.76 D, 23.77 ± 0.94 D and 20.76 ± 0.88 D, respectively. The estimated postoperative anterior chamber depth (C) was calculated by the formula C = anterior chamber depth (ACD)/0.73. This formula was determined by a different research group. C and axial length of the globe averaged for Haflinger 9.30 ± 0.54 mm and 39.43 ± 1.26 mm, for Friesian 10.12 ± 0.33 mm and 42.23 ± 1.00 mm, for Pony 8.68 ± 0.78 mm and 38.85 ± 3.13 mm, for Shetland pony 8.71 ± 0.81 mm and 37.21 ± 1.50 mm and for Warmblood 9.39 ± 0.51 mm and 40.65 ± 1.30 mm. IOL power was calculated with the Binkhorst and Retzlaff theoretical formulas. Calculated IOL power for the several breeds ranged from 18.03 D to 19.55 D. The mean value across all horses was 18.73 D determined with Binkhorst formula and 18.54 D determined with Retzlaff formula. Conclusions: Mean result of this study is: an 18.5 D IOL seemed to be the most appropriate to achieve emmetropia after IOL implantation in horses. Cataract surgery without IOL implantation results in hyperopic and visual compromised horses. Retinoscopy, keratometry and ultrasonographic biometry should be performed on every affected horse and postoperative visual outcome should be determined.
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Publication Date: 2018-04-03 PubMed ID: 29615113PubMed Central: PMC5883345DOI: 10.1186/s12917-018-1448-6Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research is an investigation into the best practices for Intraocular lens (IOL) power calculation required for cataract surgery in horses by using techniques such as retinoscopy, keratometry and ultrasonographic biometry on 98 healthy horse eyes.

Objective and Methodology

  • The study aimed to improve the postoperative visual results of cataract surgery in horses. This surgery is performed quite frequently nowadays, and it involves Phacoemulsification (technique to remove the cataract) and implantation of intraocular lenses (IOL).
  • The crucial part for ensuring a good postoperative visual outcome is the accurate determination of the IOL power, which is the ability of the lens to focus light. This was the main focus of the study.
  • The study utilized retinoscopy, keratometry and ultrasonographic biometry on 98 healthy equine eyes from 49 horses. These techniques were employed to measure the refractive state, corneal curvature, and axial location of all optical interfaces, respectively.
  • Various factors such as breed, height at the withers (shoulders), gender, age and the comparison between the left and right eye were also taken into account.
  • The determination of corresponding IOL power was done using Binkhorst and Retzlaff theoretical formulas.

Key Findings

  • The Mean refractive state of the horses was + 0.32 ± 0.66 D. The corneal curvature varied among different breeds, with values between 20.02 and 23.77 D.
  • The estimated postoperative anterior chamber depth was calculated by a formula which was provided by a different research group, giving values ranging from 8.68 mm to 10.12 mm among different breeds.
  • The IOL power was calculated using Binkhorst and Retzlaff theoretical formulas and it ranged from 18.03 D to 19.55 D depending on the breed.
  • The mean value across all horses was 18.73 D as per Binkhorst formula and 18.54 D as per Retzlaff formula.

Conclusions

  • The results suggest that an 18.5 D IOL could be the most suitable to achieve emmetropia, which is the state of vision where a distant object, at infinity, is in sharp focus with the eye lens in a relaxed, or refracted, state.
  • Performing cataract surgery without IOL implantation can result in hyperopia or farsightedness. Therefore, these findings help reduce the likelihood of visual complications post-surgery.
  • The study emphasizes that retinoscopy, keratometry and ultrasonographic biometry should be performed on every horse undergoing cataract surgery to ensure the best possible visual outcome.

Cite This Article

APA
Meister U, Görig C, Murphy CJ, Haan H, Ohnesorge B, Boevé MH. (2018). Intraocular lens power calculation for the equine eye. BMC Vet Res, 14(1), 123. https://doi.org/10.1186/s12917-018-1448-6

Publication

BMC veterinary research
ISSN: 1746-6148
NlmUniqueID: 101249759
Country: England
Language: English
Volume: 14
Issue: 1
Pages: 123

Researcher Affiliations

Meister, Ulrike
  • Stiftung Tierärztliche Hochschule Hannover, Klinik für Pferde, Bünteweg 9, 30559, Hannover, Germany. Ulrike.Meister@t-online.de.
Görig, Christiane
  • De Graafschap dierenartsen, Schimmeldijk 1, 7251 MX, Vorden, The Netherlands.
Murphy, Christopher J
  • UC Davis Health, 2315 Stockton Blvd, Sacramento, CA, 95817, USA.
Haan, Hubertus
  • HENSOLDT Optronics GmbH, Carl-Zeiss-Str. 22, 73447, Oberkochen, Germany.
Ohnesorge, Bernhard
  • Stiftung Tierärztliche Hochschule Hannover, Klinik für Pferde, Bünteweg 9, 30559, Hannover, Germany.
Boevé, Michael H
  • Stiftung Tierärztliche Hochschule Hannover, Klinik für Pferde, Bünteweg 9, 30559, Hannover, Germany.

MeSH Terms

  • Animals
  • Cornea / anatomy & histology
  • Cornea / physiology
  • Eye / anatomy & histology
  • Eye / diagnostic imaging
  • Female
  • Horses / anatomy & histology
  • Horses / physiology
  • Lenses, Intraocular / veterinary
  • Male
  • Ocular Physiological Phenomena
  • Refraction, Ocular / physiology
  • Retinoscopy / veterinary
  • Ultrasonography / veterinary

Conflict of Interest Statement

ETHICS APPROVAL AND CONSENT TO PARTICIPATE: The study was approved by the ethics commissions of the University of Veterinary Medicine Hannover, Foundation. Owners were present at the examination and their oral informed consents were given. CONSENT FOR PUBLICATION: Not applicable. COMPETING INTERESTS: The authors declare that they have no competing interests. PUBLISHER’S NOTE: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Citations

This article has been cited 2 times.
  1. Musa M, Enaholo E, Bale BI, Salati C, Spadea L, Zeppieri M. Retinoscopes: Past and present. World J Methodol 2024 Sep 20;14(3):91497.
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  2. Slenter IJM, Hermans H, Ensink JM, Willems DS, Veraa S, Grinwis GCM, Boevé MH. Clinical, ultrasonographic, and histopathologic findings in seven horses with Descemet's membrane detachment: A case series. Vet Ophthalmol 2020 Jan;23(1):181-189.
    doi: 10.1111/vop.12710pubmed: 31544302google scholar: lookup
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