Mechanism of Visual Sensations Experienced during Pars Plana Vitrectomy under Retrobulbar Anesthesia

Abstract

Purpose: To investigate the visual sensations experienced by patients during vitrectomy under retrobulbar anesthesia. Methods: 30 men and 45 women with a mean age of 65.3 ± 10.6 years underwent vitrectomy under retrobulbar anesthesia for macular disease. 28 eyes had an idiopathic epiretinal membrane, 13 had an idiopathic macular hole, 32 had macular edema (17 diabetic retinopathy and 15 retinal vein occlusion), and 2 had submacular hemorrhage. 49 patients with nonmacular disease underwent similar vitrectomy procedures and were used for comparison. An interview was conducted with the patient about his/her visual sensations during and within 3 h of the vitrectomy. Results: 70 (93.3%) of the patients reported seeing lights, 53 (70.7%) reported seeing colors, and 48 (64.0%) reported seeing movements or moving objects. Of the patients who reported seeing movements or moving objects, 44 (58.7%) reported seeing surgical instruments, and 5 (6.7%) saw the surgeon’s fingers or hands. Patients with macular diseases tended to report more visual sensations than patients with nonmacular diseases. The patients’ description and drawings appeared to arise mainly from the shadows cast by the intravitreal objects, and some patients perceived highly accurate details including the movements and color of the objects. Conclusions: Visual sensations are experienced by approximately 90% of the patients, and there may be a common mechanism by which patients perceive the intravitreal objects that are not focused on by the retina through the eye’s optical system.

Images created in a model eye during simulated cataract surgery can be the basis for images perceived by patients during cataract surgery

“…The outlines of the tips of these instruments were not as sharp as those seen during vitreous surgery. [12][13][14] In addition, they were not as sharp as the images recorded during simulated vitrectomy in the model eye, 16,17 in which the instruments were closer to the posterior surface. The greater distance of the instruments in the anterior chamber to the posterior surface made the images cast on the posterior surface more blurred.…”

“…[1][2][3][4][5] About 60% of the patients who reported seeing movements or moving objects also saw objects that resembled surgical instruments. [11][12][13][14] Although most of the descriptions have been verbal, one patient expressed her cataract surgical experiences through two paintings; one consisted of pink and blue rings, and the second consisted of a bright orange line she perceived for a short time. 6 The author suggested that these images represented the movement of a phacoemulsification probe into the eye with a possible stimulation of the color photoreceptors by the ultrasonographic energy.…”

Images of intravitreal objects projected onto posterior surface of model eye

“…A significant correlation has been found between the intraoperative visual sensations and the pre‐ or postoperative visual acuity (Sugisaka et al. 2007; Suigisaka et al. 2010).…”

“…2008). About 60% of the patients who reported seeing movements or moving objects also see surgical instruments (Suigisaka et al. 2010).…”

Visual perceptions induced by intravitreous injections of therapeutic agents

“…3 Indeed, some authors are even using IVT therapeutic agents for relatively rare disorders, such as central serous chorioretinopathy. 3 Patients' visual perceptions and experiences induced by frequently performed ophthalmic surgical procedures, such as cataract surgery (under topical [10][11][12][13][14][15] and regional anesthesia [11][12][13][14]16,17 ), glaucoma filtration surgery, 18 and vitreoretinal surgery, [19][20][21][22] are well documented. Indeed, the beneficial effect of preoperative counseling with respect to known and anticipated visual experiences during phacoemulsification cataract surgery, under topical anesthesia, in terms of reducing patients' fear, has been described.…”