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Editors Selection IGR 8-4

Electrophysiology: PERG

Comment by Vittorio Porciatti on:

15140 Pattern ERG as an early glaucoma indicator in ocular hypertension: a long-term, prospective study, Bach M; Unsoeld AS; Philippin H et al., Investigative Ophthalmology and Visual Science, 2006; 47: 4881-4887

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The conversion rate from untreated OHT to glaucoma is about 1% per year. Since the Pattern Electroretinogram (PERG) is known to be impaired in many cases of OHT, it may represent a promising candidate to discriminate converters from non converters. Bach et al. (1163) recorded serial PERGs and visual fields (6 months intervals, median follow up period of 8.2 years) in 95 eyes of 54 patients with OHT (IOP ≥25 mmHg or IOP ≥23 mmHg plus additional risk factors). The cumulative rates of IOP-lowering treatment over the observation period were 56% eye drops, 2% laser, 16% laser plus eye drops, and 8% trabeculectomy. During the follow-up period, glaucomatous visual field defects developed in 8 eyes. To assess PERG amplitude changes without the need to preselect thresholds for conversion, they performed serial ROC analyses. ROC areas enlarged steadily with the approach of conversion. One year before conversion PERG sensitivity for checks of different sizes ranged from 60 to 80%, and specificity from 71 to 83%. Positive Predictive Values ranged from 19 to 23% and Negative Predicted Values from 94 to 97%. These results support previous results showing that PERG may help to predict visual field impairment in OHT patients, and encourage the use of the PERG as an early indicator of retinal ganglion cell damage.

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