Role of Electrophysiology in the Early Diagnosis and Follow-Up of Diabetic Retinopathy

Table 3

Summary of the advantages (left side) and disadvantages (right) of electrophysiological techniques described in relation to DR. All techniques reported are noninvasive, safe, objective, and repeatable. Full knowledge and the use of them in clinical practice can provide useful information in preclinical evaluation, prognosis, and follow-up of DR.

ERG (OPs)	(i) Precociously altered in preclinical stage of DR.; (ii) Can predict progression from nonproliferative to proliferative DR.	(i) Massive retinal response, not able to detect dysfunctions localized in a single small area.
Flicker-ERG	(i) Directly reduced in proportion to the degree of DR.	(i) Nonspecific.
MfERG	(i) Able to detect localized and minimal dysfunctions.; (ii) Precociously altered in preclinical stage of DR.; (iii) Can predict macular edema and functional prognosis.	(i) Not very suitable in advanced DR and/or in the follow-up after medical or laser interventions.
PERG	(i) Able to provide macular functionality assessment in preclinical and clinical stages of DR.; (ii) Evaluates functional recovery after treatment (e.g., intravitreal).	(i) Responses being susceptible to artifacts.; (ii) Influenced by visual acuity, fixing, optical correction, transparency of optical mediums, and patient cooperation.
FERG	(i) Precociously altered in DR.	(i) Nonspecific.
VEPs	(i) Provide a reliable and objective indicator of clinically significant alterations of the visual pathway.; (ii) Able to evaluate central nervous system dysfunctions in patients with DM.; (iii) Directly correlated to diabetic age.; (iv) Directly correlated to severity of DR.	(i) Influenced by cooperation of the patient (fixing, attention), age, transparency of the optical mediums, and size of the pupil.