Volume 7 Issue 10 October, 2017
Consultation Liaison Psychiatry : Ophthalmology
Psychotropic medications have the potential to induce numerous unwanted ophthalmic side effects. Even though the percentage is less, the significance is high.
Following are the ocular changes.
1) Ocular Surface Changes
Phenothiazines can lead to impaired endothelial pump function, causing severe corneal edema leading to visual disturbance. Chlorpromazine (dose>2g/day) causes corneal epithelial keratopathy- it has a distinctive pattern of swirling lines/fine streaks in the epithelium. It causes minimal visual disturbance and usually regresses with dose tapering. Tricyclic antidepressants (TCAs) and Clozapine may cause decreased lacrimation. Persistent tear film instability and dry eye syndrome affects the ocular surface and vision. Prompt lubrication is required.
2) Ocular pigmentation
It can be Pigmentation of the skin, conjunctiva, cornea or lens and Pigmentation retinopathy. The first may cause minimal to no changes to vision, while the latter may lead to irreversible degenerative retinopathy. Chlorpromazine is known to accumulate in the skin of the eyelid, conjunctiva, posterior corneal stroma, lens and uveal tract. Photosensitization of the tissue proteins occurs in areas of increased sun exposure after accumulation of the drug in these tissues. Protective sun wear and reduced sun exposure is recommended.
3) Lenticular opacities (Cataract)
Chlorpromazine and thioridazine can cause bilateral asymmetric anterior subcapsular opacity. Few drugs can cause hyperglycemic status leading to early diabetic cataract. These opacities may not reverse with cessation of the causative agent, may need cataract surgery.
4) Accommodative Interference
TCAs, selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs) and norepinephrine reuptake inhibitors (NRIs) have been shown to cause both mydriasis {non-severe and transient visual changes} and cycloplegia {paretic effect on the ciliary muscle causing blurred near vision}. Management of accommodative disability may require an appropriate spectacle prescription until the condition improves.
5) Angle Closure Glaucoma
TCAs {Amitriptyline, Imipramine}, SSRIs (Fluoxetine, Paroxetine), SNRIs having anticholinergic effects can cause an acute angle closure with pupil block in a patient with anatomically narrow angles. The mechanism is mydriasis in an already crowded angle. Cessation of the medication, with or without initiation of other medical intervention, halts the condition and can save vision. A traditional laser peripheral iridotomy (LPI) would not be beneficial. Thus, these drugs should be prescribed cautiously in patients with narrow angles. Furthermore warranting a detailed evaluation of the eye and follow up.
6) Retinopathy and Optic Nerve Involvement
Drug toxicity can affect both the retinal pigment epithelium (RPE) and the neurosensory retina, which is not easily cleared and can lead to potential damage. Deposition of thioridazine (>800 mg/day) and chlorpromazine, may take place in the retina. Phototoxic stress causes peripheral vision loss, nyctalopia, permanent vision loss and complete blindness as damage progresses. Early detection and intervention can prevent permanent visual consequences. Benzodiazepines and Clonazepam (‘white-dot-like’ retinopathy) causes retinal toxicity. Lithium causes optic disc swelling leading to blurred vision. Resolution of this pathology has been seen with cessation of drug. All these indicates need for yearly screening for retinopathy or papillopathy
7) Impaired Sensory Perception
Carbamazepine and benzodiazepines can reduce central and paracentral color vision and Contrast sensitivity. Changes to sensory perception indicate a need for monitoring visual function above and beyond visual acuity. Regular color vision and contrast sensitivity testing should be done.
8) Ocular Motility Disorders
Carbamazepine, Topamax and SSRIs all have been associated with oculogyric crisis. Benzodiazepines can cause dysfunction of saccades and smooth-pursuits and nystagmus. Lithium causes downbeat nystagmus which can be reversed with termination of the medication. Carbamazepine can cause Diplopia, oscillopsia, gaze-evoked nystagmus, gaze palsies, downbeat nystagmus and periodic alternating nystagmus.
Take home message
Psychiatrists, Ophthalmologists and patients need to be aware of medication-induced adverse effect. Early prevention and intervention can avoid most of the serious and potentially irreversible ocular toxicities.
Dr. Pallavi B A, Assistant Professor, Dept. of Ophthalmology, MVJMC & RH, Hoskote, Bengaluru
0
0