Perimetric and peri-papillary nerve fibre layer thickness findings in multiple sclerosis

Background and purpose: Several previous studies have employed optical coherence tomography (OCT) of the optic disc and 'white-on-white' automated perimetry to evaluate optic neuritis (ON) associated with multiple sclerosis (MS). This study employed OCT, white-on-white automated perimetry as well as 'blue-on-yellow' automated perimetry to evaluate MS patients with or without episodes of ON. Methods: The MS group consisted of 56 patients with MS (27 patients with no history of ON in both eyes and 29 patients with at least one ON attack in one or both eyes), whereas the control group consisted of 56 age- and sex-matched healthy subjects. All patients underwent a complete neurological and ophthalmological examination. Peri-papillary retinal nerve fibre layer thickness (RNFLT) was evaluated using OCT. The mean defect and pattern standard deviation for both white-on-white and blue-on-yellow perimetry were also recorded. Results: RNFLT and perimetric scores were significantly lower in MS group without a history of ON and in the unaffected eyes of MS group with unilateral ON, compared with controls. MS group with more than one ON episodes had significantly compromised blue-on-yellow perimetric indices, compared with patients with one ON episode, whereas respective differences for white-on-white perimetry were not statistically significant. Conclusions: The significantly lower RNFLT and perimetric scores in MS group patients without ON, compared with control group, may possibly be attributed to sub-clinical episodes of ON or to retrograde degeneration of nerve cells from sub-clinical post-chiasmal lesions. Blue-on-yellow perimetry may be advantageous over white-on-white perimetry in evaluating MS-associated functional defects.