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Multicenter Study
. 2020 Aug 3;61(10):16.
doi: 10.1167/iovs.61.10.16.

Short-Term Changes in the Photopic Negative Response Following Intraocular Pressure Lowering in Glaucoma

Jessica Tang  1   2 , Flora Hui  1 , Xavier Hadoux  1 , Bernardo Soares  3 , Michael Jamieson  3 , Peter van Wijngaarden  1   2   3 , Michael Coote  1   2   3 , Jonathan G Crowston  1   2   4   5
Affiliations
Multicenter Study

Short-Term Changes in the Photopic Negative Response Following Intraocular Pressure Lowering in Glaucoma

Jessica Tang et al. Invest Ophthalmol Vis Sci. .

Abstract

Purpose: To evaluate the short-term changes in inner retinal function using the photopic negative response (PhNR) after intraocular pressure (IOP) reduction in glaucoma.

Methods: Forty-seven participants with glaucoma who were commencing a new or additional IOP-lowering therapy (treatment group) and 39 participants with stable glaucoma (control group) were recruited. IOP, visual field, retinal nerve fiber layer thickness, and electroretinograms (ERGs) were recorded at baseline and at a follow-up visit (3 ± 2 months). An optimized protocol developed for a portable ERG device was used to record the PhNR. The PhNR saturated amplitude (Vmax), Vmax ratio, semi-saturation constant (K), and slope of the Naka-Rushton function were analyzed.

Results: A significant percentage reduction in IOP was observed in the treatment group (28 ± 3%) compared to the control group (2 ± 3%; P < 0.0001). For PhNR Vmax, there was no significant interaction (F1,83 = 2.099, P = 0.15), but there was a significant difference between the two time points (F1,83 = 5.689, P = 0.019). Post hoc analysis showed a significant difference between baseline and 3 months in the treatment group (mean difference, 1.23 µV; 95% confidence interval [CI], 0.24-2.22) but not in the control group (0.30 µV; 95% CI, 0.78-1.38). K and slope were not significantly different in either group. Improvement beyond test-retest variability was seen in 17% of participants in the treatment group compared to 3% in the control group (P = 0.007, χ2 test).

Conclusions: The optimized protocol for measuring the PhNR detected short-term improvements in a proportion of participants following IOP reduction, although the majority showed no change.

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Conflict of interest statement

Disclosure: J. Tang, None; F. Hui, None; X. Hadoux, None; B. Soares, None; M. Jamieson, None; P. van Wijngaarden, None; M. Coote, None; J.G. Crowston, None

Figures

Figure 1.
Figure 1.
(A) Representative ERG waveforms for select stimulus strengths with the corresponding stimulus response function for (B) a-wave, (C) b-wave, and (D) PhNR. The b-wave and PhNR amplitudes were fitted with the Naka–Rushton function, where Vmax is the maximum amplitude, K is the semi-saturation constant, and n is the slope.
Figure 2.
Figure 2.
Percentage change in IOP in the control and treatment groups. Values are mean ± SD. One participant had an IOP increase following treatment and was excluded from further analysis. Unpaired Student's t-test was performed; ****P < 0.0001.
Figure 3.
Figure 3.
Group comparison at baseline and 3 months for (A) PhNR Vmax, (B) K, and (C) slope (n). Values are mean ± SD. Two-way repeated-measures ANOVA and Sidak's multiple comparison test were performed; *P = 0.019.
Figure 4.
Figure 4.
Percentage change from baseline for the control and treatment group for (A) PhNR Vmax, (B) Vmax ratio, and (C) b-wave Vmax. The gray area represents the coefficient of repeatability determined in an independent sample of healthy participants (unpublished data). Values are mean ± SD. Unpaired Student's t-test was performed; **P < 0.01, *P < 0.05.
Figure 5.
Figure 5.
Correlation of PhNR Vmax with (A) baseline IOP and (B) percent change in IOP.
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References

    1. Porciatti V, Ventura LM. Retinal ganglion cell functional plasticity and optic neuropathy: a comprehensive model. J Neuroophthalmol. 2012; 32: 354–358. - PMC - PubMed
    1. Fry LE, Fahy E, Chrysostomou V, et al. .. The coma in glaucoma: retinal ganglion cell dysfunction and recovery. Prog Retin Eye Res. 2018; 65: 77–92. - PubMed
    1. Spaeth GL. The effect of change in intraocular pressure on the natural history of glaucoma: lowering intraocular pressure in glaucoma can result in improvement of visual fields. Trans Ophthalmol Soc U K. 1985; 104: 256–264. - PubMed
    1. Leske MC, Heijl A, Hyman L, et al. .. Predictors of long-term progression in the early manifest glaucoma trial. Ophthalmology. 2007; 114: 1965–1972. - PubMed
    1. Garway-Heath DF, Crabb DP, Bunce C, et al. .. Latanoprost for open-angle glaucoma (UKGTS): a randomised, multicentre, placebo-controlled trial. Lancet. 2015; 385: 1295–1304. - PubMed

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