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Veterinary ophthalmology2022; 25(6); 483-492; doi: 10.1111/vop.13025

Effects of corneoconjunctival transposition, posterior lamellar keratoplasty and modified deep lamellar endothelial keratoplasty on streak retinoscopy in equine cadaver eyes.

Abstract: Evaluate the effects of corneoconjunctival transposition (CCT), posterior lamellar keratoplasty (PLK) and modified deep lamellar endothelial keratoplasty (DLEK) on streak retinoscopy in equine cadaver eyes. Methods: Intraocular pressure (IOP) was maintained at 25 ± 3 mmHg in 35 equine cadaver eyes. Streak retinoscopy was performed prior to (NO VISCO) and following (VISCO) intracameral injection of 1.0 ml of viscoelastic. Following optical coherence tomography (OCT), an axial CCT [n = 11] or PLK [n = 12], or peripheral DLEK [n = 12] was performed. Streak retinoscopy and OCT were repeated postoperatively. Results: Postsurgical net meridional and spherical refraction for CCT [Horizontal (H): 3.4 (95% CI 2.4-4.4) diopters (D), p < .001, Vertical (V): 3.5 (95% CI 2.7-4.4) D, p < .001, Spherical: 3.5 (95% CI 2.6-4.3) D, p < .001] and PLK [H: 3.2 (95% CI 2.2-4.1) D, p < .001, V: 2.8 (95% CI 2.0-3.6) D, p < .001, Spherical: 3.0 (95% CI 2.2-3.8) D, p < .001] were significantly increased from presurgical (VISCO) values. No difference between presurgical (VISCO) and postsurgical values were identified for the DLEK. Postoperative OCT revealed space between anterior and posterior corneal grafts and corneal undulation associated with suture placement. Conclusions: Meridional and spherical refraction had a hyperopic shift following CCT and PLK, with a significantly higher value in the vertical meridian for the CCT. Pre- and postoperative refraction was not significantly different for the DLEK. This supports that the DLEK has a lesser effect on immediate postoperative refraction compared with CCT or PLK.
© 2022 American College of Veterinary Ophthalmologists.
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Publication Date: 2022-09-19 PubMed ID: 36121370DOI: 10.1111/vop.13025Google Scholar: Lookup
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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.

This research investigates the impact of certain ocular surgeries – corneoconjunctival transposition (CCT), posterior lamellar keratoplasty (PLK), and modified deep lamellar endothelial keratoplasty (DLEK) – on the refraction of light in horse cadaver eyes, using a technique called streak retinoscopy. The findings reveal that both CCT and PLK procedures resulted in a hyperopic shift, meaning that following surgery, the eyes were more farsighted. However, the DLEK procedure did not significantly change the eye’s refraction.

Methodology

  • The study was conducted on 35 equine cadaver eyes, with the intraocular pressure (IOP) maintained at 25 ± 3 mmHg.
  • Streak retinoscopy, a procedure that examines the refractive state of the eye, was performed before and after injecting a solution called viscoelastic into the eye chamber.
  • Then, axial corneoconjunctival transposition (CCT) was performed on 11 eyes, posterior lamellar keratoplasty (PLK) on 12 eyes, and peripheral deep lamellar endothelial keratoplasty (DLEK) on the remaining 12.
  • After the operations, streak retinoscopy was conducted once more, followed by optical coherence tomography (OCT) – a non-invasive medical imaging technique used to visualize different portions of the eye.

Results

  • After the surgeries, meridional (directional) and spherical (overall) refraction was significantly increased for both CCT and PLK, indicating a hyperopic, or farsighted, shift. This was particularly clear in the vertical meridian for CCT cases.
  • In contrast, the DLEK procedure did not cause significant changes in pre- and postoperative refraction.
  • Postoperative OCT revealed the presence of space between the anterior (front) and posterior (back) corneal grafts and corneal undulation (waving or rippling) associated with suture placement.

Conclusions

  • The findings suggest that refraction in the eye changes following CCT and PLK surgeries, making the eye more farsighted.
  • The DLEK procedure, however, does not significantly affect immediate postoperative refraction. As such, DLEK may be preferred when seeking to maintain preoperative refractive conditions.

Cite This Article

APA
Charnock LN, Boveland SD, Groover ES, Moore PA, McMullen RJ. (2022). Effects of corneoconjunctival transposition, posterior lamellar keratoplasty and modified deep lamellar endothelial keratoplasty on streak retinoscopy in equine cadaver eyes. Vet Ophthalmol, 25(6), 483-492. https://doi.org/10.1111/vop.13025

Publication

Veterinary ophthalmology
ISSN: 1463-5224
NlmUniqueID: 100887377
Country: England
Language: English
Volume: 25
Issue: 6
Pages: 483-492

Researcher Affiliations

Charnock, Lauren N
  • College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.
Boveland, Shannon D
  • College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.
Groover, Erin S
  • College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.
Moore, Phillip A
  • College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.
McMullen, Richard J
  • College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.

MeSH Terms

  • Horses
  • Animals
  • Endothelium, Corneal
  • Retinoscopy
  • Visual Acuity
  • Corneal Transplantation / veterinary
  • Corneal Transplantation / methods
  • Cadaver
  • Horse Diseases / surgery

Grant Funding

  • Auburn University Department of Clinical Sciences Resident Research Grant

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