Longitudinal outcomes of circumlimbal suture model-induced chronic ocular hypertension in Sprague-Dawley albino rats

Yamunadevi Lakshmanan, Francisca Siu Yin Wong, Bing Zuo, Bang Viet Bui, Henry Ho Lung Chan

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Abstract

Purpose: To characterise longitudinal structural and functional changes in albino Sprague-Dawley rats following circumlimbal suture ocular hypertension (OHT) induction. Methods: Ten-week-old rats (n = 24) underwent suture implantation around the limbal region in both eyes. On the next day, the suture was removed from one eye (control eyes) and left intact in the other eye (OHT eyes) of each animal. Intraocular pressure (IOP) was monitored weekly twice for the next 15 weeks. Optical coherence tomography (OCT) and electroretinogram (ERG) were measured at baseline and weeks 4, 8, 12, and 15, and eyes were then collected for histological assessment. Results: Sutured eyes (n = 12) developed IOP elevation of ~ 50% in the first 2 weeks that was sustained at ~ 25% above the control eye up to week 15 (p = 0.001). Animals with insufficient IOP elevation (n = 6), corneal changes (n = 3), and attrition (n = 3) were excluded from the analysis. OHT eyes developed significant retinal nerve fibre layer (RNFL) thinning (week 4: − 19 ± 14%, p = 0.10; week 8: − 17 ± 12%, p = 0.04; week 12: − 16 ± 10%, p = 0.04, relative to baseline) and reduction in retinal ganglion cell (RGC) density (− 32 ± 26%, p = 0.02). At week 15, both inner (9 ± 7%, p = 0.01) and outer retinal layer thicknesses (6.0 ± 5%, p = 0.001) showed a mild increase in thicknesses. The positive scotopic threshold response (− 28 ± 25%, p = 0.04) and a-wave were significantly reduced at week 12 (− 35 ± 21%; p = 0.04), whereas b-wave was not significantly affected (week 12: − 18 ± 27%, p = 0.24). Conclusion: The circumlimbal suture model produced a chronic, moderate IOP elevation in an albino strain that led to RNFL thinning and reduced RGC density along with the reductions in ganglion and photoreceptoral cell functions. There was a small thickening in both outer and inner retinal layers.

Original languageEnglish
Pages (from-to)2715-2728
Number of pages14
JournalGraefe's Archive for Clinical and Experimental Ophthalmology
Volume258
Issue number12
Early online date5 Jul 2020
DOIs
Publication statusPublished - Dec 2020

Keywords

  • Albino rat
  • Animal model
  • Circumlimbal suture
  • Glaucoma
  • Intraocular pressure
  • Ocular hypertension

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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