Dr. Abhishek Mandal, Ph.D.
Founder, Vision Science Academy, London, UK.
Vision Science Academy Exclusive
Illicit drugs can be administered into the human body through various routes including inhalation of smoke, intravenous injection, skin patches, and oral uptake. Human vision can be drastically impacted through consumption of a plethora of recreational substances which makes it essential for eye health practitioners to possess a wealth of knowledge in this regard. The long-term catastrophic effects of such drugs of abuse range from minimal eye infection to permanent loss of vision.
Marijuana and Eye Health
The cannabinoids constitute the main active ingredient in Marijuana, one of the most widely used intoxicants worldwide. Marijuana can substantially impact a consumer’s visual perception in the following ways: (1) Decrease in visual acuity; (2) Alteration of contrast sensitivity, and (3) Poor depth perception. These visual disturbances can severely impair a person’s driving capabilities (Lalanne et al., 2017). Moreover, the younger the person at the time of first cannabis use, the greater the severity of visual deterioration (Ortiz-Peregrina, Ortiz, Castro-Torres, Jiménez, & Anera, 2020). In a study conducted among the U.S military veterans, it was found that chronic marijuana smokers had a remarkably higher risk of loss of visual acuity as compared to those who did not consume cannabis (McDaniel et al., 2020).
Alcohol and Eye Health
Alcohol abuse can lead to a progressive decline in a multitude of visual parameters such as pupillary size and its reactivity to light. Conjunctival congestion, double vision, and nystagmus are also a direct result of acute alcohol abuse. Furthermore, poor night vision is yet another major visual dysfunction encountered among alcoholics. A chronic alcohol abuse can gradually lead to a disproportionate mobility of the eyeballs as well as age-related degeneration of macula (ARMD). Adulteration of alcohol with toxic agents such as methanol can potentiate a highly fatal outcome. In terms of vision, methanol can be associated with the following significant changes: (1) Optic neuropathy due to intracellular mitochondrial shutdown; (2) Optic nerve demyelination, and (3) Optic disc degeneration and retrobulbar neuritis (Dhingra, Kaur, & Ram, 2019).
Opiates and Eye Health
Opiates include strong analgesics such as morphine and codeine, and can be administered into the body through various routes. Opioid poisoning is associated with a characteristic finding of pinpoint pupils where the latter become severely constricted and unresponsive to light. Additionally, opiate abuse can also produce nystagmus as well as abnormal saccadic eye movements. Intravenous route of administration can be rarely associated with the pathogenesis of microemboli within the retinal vessels, thereby leading to a sharp decline in visual acuity. Furthermore, retinal ischemia and neovascularization are some other pathological events strongly associated with opiate poisoning (Dhingra et al., 2019).
Other Intoxicants
Several other classes of illicit pharmacological agents are associated with a poor visual outcome. These include sympathomimetic drugs such as cocaine, methamphetamine, and cyclazodone. These stimulants can not only cause mydriasis but they are also associated with varying degrees of ophthalmoplegia and proptosis. Besides psychostimulants, sedatives and hallucinogens are also quite notorious for their adverse effects on vision (Mills, Spruill, Kanne, Parkman, & Zhang, 2001).
Concluding Remarks
From the viewpoint of an ophthalmologist or optometrist, it is essential to recognise the early visual manifestations encountered among different drug abusers. This can help salvage as much of the visual function as possible.
References
Dhingra, D., Kaur, S., & Ram, J. (2019). Illicit drugs: Effects on eye. Indian J Med Res, 150 (3), 228-238.
doi: 10.4103/ijmr.IJMR_1210_17
Lalanne, L., Ferrand-Devouge, E., Kirchherr, S., Rauch, L., Koning, E., Speeg, C., . . . Giersch, A. (2017). Impaired contrast sensitivity at low spatial frequency in cannabis users with early onset. European Neuropsychopharmacology,
27 (12), 1289-1297. doi:https://doi.org/10.1016/j.euroneuro.2017.09.006
McDaniel, J. T., Jenkins, W. D., Albright, D. L., Null, D., McIntosh, S., & McDaniel, M. R. (2020). Illicit drug use and self- reported vision loss among military service members or veterans. bmjmilitary-2020-001518.
doi:10.1136/bmjmilitary-2020-001518 %J BMJ Military Health
Mills, K. C., Spruill, S. E., Kanne, R. W., Parkman, K. M., & Zhang, Y. (2001). The Influence of Stimulants, Sedatives, and Fatigue on Tunnel Vision: Risk Factors for Driving and Piloting. 43(2), 310-327. doi:10.1518/001872001775900878
Ortiz-Peregrina, S., Ortiz, C., Castro-Torres, J. J., Jiménez, J. R., & Anera, R. G. (2020). Effects of Smoking Cannabis on Visual Function and Driving Performance. A Driving-Simulator Based Study. 17(23), 9033.
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