case of pupil-sparing oculomotor nerve palsy

A 55 year old patient presented with sudden onset drooping of the left upper eyelid and occasional double vision of one day duration. There was no history of vomiting, headache or loss of consciousness. He was diabetic for 22 years, controlled on Metformin 0.5mg twice a day and Mixtard insulin 20 units twice a day. On presentation his vitals were stable and blood sugar [fasting] was 165mg%. Visual acuity was 6/9 in both eyes. There was severe ptosis in the left eye. The left eye showed 20 degree exotropia. All ocular movements in the left eye except abduction were limited. Examination of the other cranial nerves was normal. The pupil of the left eye was of normal size and reacting to light. The fundus of the left eye showed mild non proliferative diabetic retinopathy. Examination of the right eye showed normal ocular movements and anterior segment. Fundus of right eye showed mild non proliferative diabetic retinopathy. The patient was followed up and pupil reactions in the left eye remained normal. A diagnosis of pupil sparing oculomotor nerve palsy was made and patient was referred for strict blood sugar control. Patient was asked to occlude the left eye to alleviate diplopia. The ptosis and double vision improved in 6 weeks. The pupil should be carefully evaluated in a case of oculomotor nerve palsy as pupil involving palsy predominantly have a surgical cause and need a neuro-radiological imaging while pupil sparing causes predominantly have medical causes like diabetes and resolve spontaneously