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Reversal of functional loss in a rat model of chronic intraocular pressure elevation
Author(s) -
Liu HsinHua,
He Zheng,
Nguyen Christine T. O.,
Vingrys Algis J.,
Bui Bang V.
Publication year - 2017
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/opo.12331
Subject(s) - ophthalmology , intraocular pressure , medicine , ocular hypertension , nerve fiber layer , ganglion , retinal , ganglion cell layer , retinal ganglion cell , optical coherence tomography , fibrous joint , surgery , anatomy
Purpose This pilot study considered whether intraocular pressure ( IOP ) lowering could reverse ganglion cell dysfunction in a rat model of chronic ocular hypertension. Methods A circumlimbal suture was applied in one eye to induce ocular hypertension ( n = 7) in Long‐Evans rats. The contralateral eye served as an untreated control. After 8 weeks of IOP elevation the suture was removed to lower IOP for the remaining 7 weeks. Electroretinogram ( ERG ) and optical coherence tomography ( OCT ) were measured at baseline, 2, 4, 8, 12 and 15 weeks. Retinae were collected for histology at week 15. Results In sutured eyes, IOP was elevated by 7–11 mmHg above control eyes (12 ± 0.2 mmHg [standard error of the mean]). Eight weeks of chronic IOP elevation resulted in a reduction of the ganglion cell mediated positive Scotopic Threshold Response ( pSTR , −25 ± 7% of baseline), as well as smaller photoreceptor (−7 ± 4%) and bipolar cell mediated responses (−6 ± 5%). After suture removal, IOP recovered to normal. By 15 weeks the a ‐wave (0 ± 6%), b ‐wave (−2 ± 6%) and pSTR had recovered back to baseline (from −25 ± 7% to −4 ± 6%). The retinal nerve fiber layer was thinned by −9 ± 3% at week 8 and showed no further decline at week 15 (−10 ± 2%). Cell numbers in the ganglion cell layer were similar between suture removal and control eyes at week 15 (3543 ± 478 vs 4057 ± 476 cells mm −2 ). Conclusions The circumlimbal suture model might be a useful platform to study the reversibility of neuronal dysfunction from chronic IOP challenge.