Use of the Scanning Laser Ophthalmoscope in Assessing Patients with Functional Visual Loss

Abstract

Abstract: : Purpose: To demonstrate the use of the scanning laser ophthalmoscope(SLO) in assessing patients suspected of functional visual loss. Methods: Five case reports. All five patients presented complaining of poor vision. In each case, best corrected vision was found to be inconsistent with the patient’s performance on complete eye exam. Three patients had eye pathology accounting for some degree of decreased vision, but a nonorganic component was suspected. Further assessment was made including full neuro-ophthalmologic exam and SLO testing. Patients were given cues to suggest they would be able to see the figure projected by the instrument even with their current visual acuity. Photographs were taken recording patient fixation as well as the orientation and location of the projected letter on the retina. The corresponding Snellen acuity to the letter was noted in each case. The patients' medical records and clinical outcomes were reviewed. Results: Good fixation was present in all patients. Four patients had fixation localized to the center of the clinical fovea. One patient who was status post retinal detachment repair had slightly eccentric, but macular fixation. SLO testing recorded the visual acuities to be greater than claimed by the patients on clinical exam in all cases. The visual acuities in the affected eyes ranged from 20/100 to light perception on presentation. The range of the visual acuities in the affected eyes by SLO testing was from 20/60 to 20/800. Two patients subsequently had improvement in their clinical visual acuity shortly after SLO testing without any objective change in their eye exam. Four out of five patients had specific issues pertaining to disability based on their poor vision. Conclusions: The scanning laser ophthalmoscope provides information important in the evaluation of suspected functional visual loss. The SLO can document the location of patient fixation and test visual acuity under direct fundus visualization. This case series demonstrates the SLO is useful in assessing patients with nonorganic visual loss, and patients with a nonorganic visual loss component superimposed on their organic ocular disease.

Keywords: visual impairment: neuro-ophthalmological dise • immunohistochemistry • imaging/image analysis: clinical