General anesthesia is often a necessity for patients undergoing complex surgical procedures or in cases where local anesthesia is not an option. Though some patients may prefer general anesthesia, they may not realize the health risks associated with general anesthesia. Severe complications, which are uncommon, include anaphylactic shock, cardiovascular collapse, aspiration pneumonitis, lung collapse, hypothermia, hypoxic brain injury, and in some cases, death [1,2].  In addition to these risks, patients can sometimes experience ocular (eye) complications due to anesthesia.  

Ocular complications because of general anesthesia are rare, with one study showing a rate 2.3 cases per 10,000 [4]. Generally these complications usually are not vision-threatening, but in some cases, postoperative vision loss can occur. Corneal abrasions are the most common ocular complications in patients undergoing general anesthesia. The most common cause of corneal abrasions is improper taping and covering of the eyes during surgery which causes drying of the corneal surface and subsequent injury [3-7]. These ulcers can be mild or severe and patients usually complain of blurry vision, sensitivity to light, and painful watery eyes in the postoperative period [3]. Other mild ocular complications that can happen after anesthesia are conjunctivitis/red eye, blurred vision persisting longer than 1 day, chemical injury or eyelid hematoma [7].  

Though exceedingly rare, permanent vision loss is a risk of general anesthesia. Studies have demonstrated that postoperative vision loss (POVL) was much more common in patients undergoing cardiac or spinal surgery [3, 7]. Causes of permanent vision loss are usually due to ischemia that happens to the cerebral cortex, the retina, which is the thin layer of cells located in the back of the eye, or the optic nerve [3-7]. The optic nerve connects directly from the retina to various regions of the brain, and can be damaged in surgeries where patients are placed in positions leading to increased cranial pressure. The type of blindness patients experience, whether partial or complete, depends on the area in the visual pathway affected by ischemia.  

Although general anesthesia is considered safe, it is important to be aware of the potential risks and side effects associated with it, including ocular complications. Patients should always discuss the potential risks with their doctor before undergoing a procedure. In many cases, ocular complications are treatable and reversible, but in some cases, they may lead to permanent vision loss. For this reason, it is important to be aware of the potential risks and to take steps to reduce them. 

References 

1. Aitkenhead, A. R. (2005). Injuries associated with anaesthesia. A global perspective. British journal of anaesthesia, 95(1), 95-109. 
2. Harris, M., & Chung, F. (2013). Complications of general anesthesia. Clinics in Plastic Surgery, 40(4), 503-513. 
3. Roth, Steven, et al. “Eye injuries after nonocular surgery: a study of 60,965 anesthetics from 1988 to 1992.” The Journal of the American Society of Anesthesiologists 85.5 (1996): 1020-1027. 
4. Kara-Junior, N., Espindola, R. F. D., Valverde Filho, J., Rosa, C. P., Ottoboni, A., & Silva, E. D. (2015). Ocular risk management in patients undergoing general anesthesia: an analysis of 39,431 surgeries. Clinics, 70, 541-543. 
5. Singh, R. B., Khera, T., Ly, V., Saini, C., Cho, W., Shergill, S., … & Agarwal, A. (2021). Ocular complications of perioperative anesthesia: a review. Graefe’s Archive for Clinical and Experimental Ophthalmology, 259, 2069-2083. 
6. Nuzzi, R., & Tridico, F. (2016, November). Ocular complications in laparoscopic surgery: review of existing literature and possible prevention and treatment. In Seminars in Ophthalmology (Vol. 31, No. 6, pp. 584-592). Informa Healthcare. 
7. Shen, Y., Drum, M., & Roth, S. (2009). The prevalence of perioperative visual loss in the United States: a 10-year study from 1996 to 2005 of spinal, orthopedic, cardiac, and general surgery. Anesthesia & Analgesia, 109(5), 1534-1545.