Decompensated Strabismus Causing Diplopia Common Among Post-Cataract Visual Disturbances 

Patients with a visual disturbance fewer than 6 months after cataract surgery most commonly have decompensated strabismus causing diplopia, according to a study published in Journal of Neuro-Ophthalmology. Researchers advocate for surgeons to complete a detailed history and assess ocular alignment preoperatively to identify patients at risk.

The retrospective chart review included 173 adults with new-onset visual disturbance referred from internal (36) or external (137) surgeons to neuro-ophthalmologists at the University of Pennsylvania from January 2010 until October 2019. A secondary analysis considered patients who experienced uneventful cataract procedures at Scheie Eye Institute. Prior neuro-ophthalmic conditions or combination surgeries were among the exclusion criteria.

Of the 173 participants, 61% displayed neuro-ophthalmic etiologies: 40% with efferent and 21% afferent visual pathway disorders. Remaining diagnoses comprised 36% of disturbances originating with ocular syndromes such as dry eye disease, iritis, retinal disorders, positive or negative dysphotopsia, and others; and 3% from nonorganic visual loss or systemic diseases including inner ear dysfunction or orthostatic hypotension.

Afferent visual pathway disruptions accounted for 34% of cases from neuro-ophthalmic causes; neuropathies such as nonarteritic ischemic optic neuropathy (NAION), compressive optic neuropathy, idiopathic pathology, and nutritional/toxic effects; or from posterior cortical atrophy. Alternatively, efferent pathway disorders, 66% of neuro-ophthalmic diagnoses arose from thyroid eye disease, vasculopathic cranial nerve palsies, and other sources — but a vast majority of efferent dysfunction, 53 of 70 — and 50% of all neuro-ophthalmic symptoms grew from decompensated strabismus. Of the latter, 17% had a history of temporary double vision.

“Because postoperative diplopia from decompensated strabismus was the most commonly identified neuro-ophthalmic etiology, a history of strabismus, diplopia, or prism wear should be assessed before cataract surgery,” the investigators explain. NAION was the next most frequent origin of visual disruptions, at 12% of neuro-ophthalmic cases.

During the study period, 36 of 13,715 cataract surgery patients at the Institute were referred for neuro-ophthalmic consults. For those referred, 20 received neuro-ophthalmic diagnoses for visual disturbances, a prevalence of 0.15%. Most of these individuals, 17 (85%), had diplopia.

In previous research a prevalence of 0.17% has been reported. Again, decompensated strabismus causing diplopia occurred; as well as extraocular muscle restriction or paresis; pre-existing amblyopia or anisometropia; postoperative monovision or anisometropia; or systemic disease that developed near the time of surgery. Convergence insufficiency resurfaced. Other research has demonstrated that vision problems from chiasmal compression can be misread as caused by cataract, although these 2 pathologies may exist together. Investigators note that prior neuro-ophthalmic difficulties may be detected by presence of an afferent pupillary defect, field loss, dyschromatopsia, or visual defect more than what can be prompted by the cataract.

A limitation of this study is its retrospective design. However, prior analyses that evaluated post-cataract problems such as NAION may reflect earlier stages of surgical technology, the analysis adds. Advances from scleral incisions to smaller corneal wound construction may be reducing ocular trauma and post-surgical inflammation.