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L.M. Ventura, V. Porciatti, N.M. Sorokac, P.F. Palmberg; Relationship Between Improvement of Pattern Electroretinogram Amplitude and Reduction of Intraocular Pressure in Glaucoma . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3776.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the relationship between improvement of retinal ganglion cell (RGC) function and reduction of intraocular pressure (IOP) in glaucoma. Methods: RGC function has been evaluated by means of the pattern electroretinogram (PERG) in response to high–contrast gratings alternating at 16 Hz. The PERG has been recorded simultaneously from both eyes of 4 patients at different stages of glaucoma with elevated IOP (average initial value = 41 ± 18 mm Hg). PERG and IOP were measured before and at different intervals after IOP reduction with topical treatment. Results: Decreasing the IOP resulted in a marked improvement of PERG amplitude in all but one treated eye (median 100.9%, quartiles 32%, 166%). The improvement was relatively stable with time. The eye that did not show PERG improvement had an advanced glaucomatous visual field loss. In all eyes, IOP reduction was maximal the day after the initiation of treatment. The maximal improvement of PERG amplitude, however, was delayed, compared to the time course of IOP reduction, in 75% of eyes. The relationship between PERG amplitude and IOP was non–linear, and was well described by a power function with a median exponent of –0.445 (quartiles –0.42 –0.52). That is, the amount of PERG amplitude improvement per unit of IOP reduction was relatively greater below 21 mm Hg than above 21 mm Hg. Conclusions: The improvement in PERG amplitude after IOP lowering suggests that a population of viable RGCs is dysfunctional due to elevated IOP. Reducing IOP results in a relatively stable improvement of RGC function. Our data suggest that the PERG may be useful to establish that target IOP where RGC function is maximally improved.
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