#CN III COMPRESSION AND FIXED DILATED PUPIL FULL#

#CN III COMPRESSION AND FIXED DILATED PUPIL FULL#

A comitant deviation, such as a decompensating heterophoria, presents with an intermittent or gradual onset, shows full range of ocular movement in all positions of gaze and may have a history of childhood strabismus. A key point in alignment testing is the evaluation for comitancy, in which the size of an ocular deviation remains the same in all directions of gaze. A phoria occurs when the misalignment is not obvious, and diplopia occurs only when binocularity is disrupted. Ocular misalignment may be caused by a tropia, and an obvious eye turn is noted. Ocular motility and alignment testing may include the cover/uncover test, alternate cover test, Maddox rod and corneal light reflex. Many antidepressants may aggravate the symptoms of a convergence insufficiency by affecting accommodation.

2,6,10Īlthough less frequently, certain medications can cause binocular diplopia, such as anticonvulsants, selective serotonin reuptake inhibitor antidepressants, erectile dysfunction medications, migraine therapies and other medications with anticholinergic properties. 2,3,10 A systemic health history should include questions regarding trauma, diabetes, hypertension, thyroid disease, cancer, infection and immunosuppression-all of which could cause CN palsies and diplopia through vascular or restrictive mechanisms. A thorough systemic health history and step-by-step examination is key to localizing most underlying etiologies. The type of diplopia the patient complains of-horizontal, vertical or diagonal worse at distance or near increased or decreased in a particular gaze position-helps to identify which extraocular muscle is involved. Unlike monocular diplopia, binocular diplopia, due to ocular misalignment, will disappear when either eye is covered. 9Īs many as 60% of MG patients, such as this one, present with ptosis and diplopia. 4,7,8 Medications (e.g., antidepressants, antihistamines, diuretics) may contribute to ocular surface dryness and induce a monocular diplopia. Decreased vision due to uncorrected astigmatism, dry eye and tear film deficiencies, corneal pathology or scarring, iris abnormalities, lenticular changes, vitreal opacities and macular disease are all possible causes of monocular diplopia. This finding is rarely due to cortex lesion and is generally attributable to causes within the eye itself. Clinicians should have the patient cover each eye separately when testing for monocular diplopia. 3,4 Monocular Diplopiaĭiplopia that persists when one eye is covered falls into the category of monocular diplopia, or polyopia (greater than two images). The clinician must determine if the diplopia is monocular or binocular, as binocular diplopia may have a life-threatening cause.

The first step on the path to proper identification is a thorough patient history. 6 A systematic approach to the differentials is key to identifying and treating benign causes-and promptly referring patients when it is vision or life threatening.ĬN VI palsy, seen here in the right eye, accounts for 50% of all isolated CN palsies. 4,5 Most etiologies will fall into one of five categories: (1) refractive, (2) binocular vision disorder, (3) orbital disease, (4) neuromuscular junction dysfunction, or (5) injury to the central nervous system/cranial nerves (CNs). 2,3 While the cause can be benign, some cases, such as those accompanied by new headache, ocular pain, unilateral pupil dilation, muscle weakness, ptosis, trauma or papilledema, raise red flags for immediate referral. 1 Constant diplopia with acute onset will have different differentials than intermittent diplopia, for example. A patient presenting with diplopia-whether horizontal, vertical or diagonal-is often a clinical challenge.

Cn iii compression and fixed dilated pupil