Retained visual sensation during cataract surgery: author’s reply

Abstract

Dr. Verma’s patient gave a beautiful artist’s rendition of the visual images she experienced during phacoemulsification and intraocular lens implantation under topical anesthesia. In our studies, we also invited all the patients (none of them an artist) to draw their visual images with color pencils on a plain piece of paper immediately after their interview.1Au Eong K.G. Low C.H. Heng W.J. et al.Subjective visual experience during phacoemulsification and intraocular lens implantation under topical anesthesia.Ophthalmology. 2000; 107: 248-250Abstract Full Text Full Text PDF PubMed Scopus (73) Google Scholar, 2Au Eong K.G. Lee H.M. Lim A.T.H. et al.Subjective visual experience during extracapsular cataract extraction and intraocular lens implantation under retrobulbar anesthesia.Eye. 1999; 13: 325-328Crossref PubMed Scopus (39) Google Scholar, 3Au Eong KG, Lim TH, Lee HM, et al. Subjective visual experience during phacoemulsification and intraocular lens implantation using retrobulbar anesthesia. J Cataract Refract Surg 2000;26:842–6.Google Scholar Approximately half of the patients were able to produce a rough sketch of their visual experience, although many had difficulty drawing a still picture from the kaleidoscope of moving colors and shapes they experienced. Although some patients drew only a sketch of the visual images they experienced during a specific stage of the surgery, others drew a montage of images from different stages of the procedure. The sketches drawn varied greatly, and no two drawings were alike. The patients’ interpretation of their sketches also varied enormously, and some reported seeing “balls of yellow”; “simmering blue stars”; “a pair of cat’s eyes” (probably from the two light sources in the microscope); surgical instruments; and shapes of circles, ovals, waves, and stars. Some of these sketches were presented at the annual meetings of the Association for Research in Vision and Ophthalmology (Au Eong KG, Low CH, Lim ATH, et al. [Invest Ophthalmol Vis Sci 38(Suppl):S181, 1997] and Voon LW, Au Eong KG, Lee HM, et al. [Invest Ophthalmol Vis Sci 38(Suppl):S181, 1997]) and of the American Academy of Ophthalmology (Au Eong KG, Low CH, Ho SH, et al, presented at the AAO Annual Meeting, San Francisco, California, 1997). We believe the visual images seen by each patient are unique, because they are likely to be a combination of images of objects close to but outside the eye (e.g., fingers, hands, instruments) and entoptic phenomena produced by objects and structures on the corneal surface and in the eye. Dynamic factors such as moving fluids and bubbles on the corneal surface and in the eye, moving instruments in the eye, and the ever-changing shape and opacity of the lens as it is being emulsified (or expressed) and aspirated probably produce the changing kaleidoscope of colors and shapes reported by many of the patients. In addition, the refractive state of the eye also changes during the surgery, because the refractive structures of the eye such as the cornea and lens are deformed, and the eye is rendered from the phakic to aphakic, and finally pseudophakic state. For these reasons, and because a painting is based on one’s subjective interpretation of what one sees, Dr. Verma’s patient’s painting is different from those drawn by our patients. We are unable to confirm whether Dr. Verma’s patient’s painting depicts the movements of the phaco probe in the eye with possible stimulation of the cones by ultrasonographic energy. We doubt whether ultrasonographic energy plays a key role in the genesis of these images, because our experience with cataract patients operated on by extracapsular cataract extraction show that some of them could experience images similar to those who had phacoemulsification.2Au Eong K.G. Lee H.M. Lim A.T.H. et al.Subjective visual experience during extracapsular cataract extraction and intraocular lens implantation under retrobulbar anesthesia.Eye. 1999; 13: 325-328Crossref PubMed Scopus (39) Google Scholar, 3Au Eong KG, Lim TH, Lee HM, et al. Subjective visual experience during phacoemulsification and intraocular lens implantation using retrobulbar anesthesia. J Cataract Refract Surg 2000;26:842–6.Google Scholar