Purpose.A novel method of detecting focal visual field defects in glaucoma patients using a modified slit-lamp and 78D lens is described. Method.It was noticed that when a horizontally orientated slit-beam was projected above and below the optic disc in glaucoma patients,some subjects perceived a 'gap' in the slit-beam corresponding to the position of documented retinal nerve fibre layer defects and/or field defects. Modification of a standard Haag-Streit 900 slit-lamp was performed to allow projection of a thin ring of light concentric with the optic disc. Patients are asked whether they perceive a complete ring.The method was assessed prospectively in both eyes of 20 glaucoma patients and glaucoma suspects who were selected because of the presence of focal thinning of the retinal nerve fibre layer(RNFL) imaged using a scanning laser ophthalmoscope (with or without corresponding visual field defects on automated perimetry respectively).Results.Subjects within a normal control group reported perceiving a 'complete' ring, whereas the glaucoma patients/suspects reported the presence of a 'gap' or focal dimming of part of the projected stimulus. The spatial correlations between the site of field defects/RNFL thinning and the site of the perceived stimulus defect are presented.The required modifications to the slit-lamp are outlined. Conclusions.This simple, rapid test of visual function can be performed with standard biomicroscopic apparatus and may be of value in the initial office assessment of patients suspected of having glaucoma.
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|