Diagnostic clues of IOP pulsation on applanation tonometry in carotid-cavernous fistula patients

Carotid-cavernous fistula (CCF) is an abnormal communication between the cavernous sinus and the carotid arterial system and exhibits typical symptoms of red eye, diplopia, blurred vision, headache, and murmur. However, the symptoms for CCF may vary and can lead to misdiagnosis. IOP pulsations provide a hint leading to suspicion of CCF. We report three cases related to CCF differential diagnosis: two cases of CCF patients and one case of conjunctivitis with corkscrew conjunctival vessels. The case 1 patient, with a typical unilateral CCF, exhibited significant IOP pulsation in Goldmann tonometry measurements in the affected eye. The case 2 patient did not show typical symptoms of CCF except asymmetric upper eyelid swelling (right > left). In clinical evaluation, IOP elevation in the right eye and IOP pulsation in both eyes were noted. Based on radiology, the patient was diagnosed with bilateral CCF. The case 3 patient was referred to our institution for differential diagnosis of CCF. The patient had corkscrew conjunctival vessels in both eyes, which had appeared after he had been revived through CPR (cardiopulmonary resuscitation) 25 years prior. IOP pulsation was not observed in Goldmann tonometry. Radiology test result for arterio-venous fistula was negative in the case 3 patient. For diagnosis of CCF, IOP pulsation by Goldmann applanation tonometry exhibits a good correlation with the disease in our cases and provides useful diagnostic clues.