Abstract
Purpose: :
To evaluate sensitivity of two multifocal electrophysiological tests, mfONHC and mfVEP, in early diagnosis of glaucomatous optic nerve damage in glaucoma suspects and early glaucoma.
Methods: :
This prospective study includes glaucoma suspects (GS) and established patients with early glaucoma (EGP). Testing is performed using VERISTM multifocal system (San Mateo, California). Each patient is examined with two multifocal protocols, mfONHC and mfVEP (2 channels), at a single time point. MfONHC and mfVEP are analyzed in visual field-comparable (indirect) view. Analysis of the recordings is performed using VERISTM software version 5.2. Correlation between mfONHC and mfVEP losses was calculated. At the present, mean (±St.Dev.) patients’ age is 52.3±9.7 (ranging between 40 and 64 years of age). Visual acuity is 20/20-20/25 in GS and 20/25-20/70 in EGP. Intraocular pressure measured by applanation tonometry is 17.2±6.5 mmHg (ranging between 9 and 27 mmHg) in GS and 11.3±2.2 mmHg (ranging between 9 and 14 mmHg) in EGP. 24-2 Humphrey visual fields are normal in GS and have sensitivity loss ranging between 4 and 18 dB in EGP.
Results: :
At present, we have results for mfONHC and mfVEP from six GS (10 eyes) and two EGP (3 eyes). All GS revealed lost mfONHC within either superior nasal sector (2 eyes), entire nasal half (5 eyes), or part of superior temporal sector, entire nasal half and part of inferior temporal sector together (3 eyes). EGP showed no detectable mfONHC. MfVEP showed depressed or undetectable responses within nasal sector in all patients, with strong positive correlation between the two tests (correlation coefficient r=0.67).
Conclusions: :
While atrophy of over 50% of the optic nerve fibers is necessary to show glaucomatous visual filed losses, mfONHC and mfVEP are highly sensitive tools in earlier detection of glaucomatous damage of the optic nerve in glaucoma suspects. More patients will be examined.
Keywords: optic nerve • visual cortex • electrophysiology: clinical