1754
LETTERS
Reply : Good idea. Thanks for reading our article. dThomas A. Oetting, MD
Photic retinal injury from operating microscope during cataract surgery We read Dr. Tengroth's account of his visual experience after cataract surgery1 and are relieved that this distressing situation resolved without long-term sequelae. The article highlights the importance of a patient's visual experiences during and after cataract surgery, which is an aspect of healthcare that deserves more attention from ophthalmologists. These experiences, and our patients' preoperative expectations, affect patients' overall satisfaction with the entire medical encounter.2 Dr. Tengroth reported a temporary loss of blue cone response after uneventful cataract surgery,1 which was presumed to be due to photic retinal injury after exposure to the intense light from the operating microscope during surgery. The concept of ultraviolet (UV) radiation and blue-light hazards causing retinal thermal and photochemical injury from operating microscopes has been described.3 At the more severe end of the spectrum, Khwarg et al.4 described an incidence of 7% for operating microscope light-induced retinopathy in 135 consecutive patients who had cataract surgery. These cases of light-induced retinopathy demonstrated recognizable fundus lesions that appeared as focal pigment epithelial changes and could be demonstrated on fundus fluorescein angiography as sharply demarcated transmission defects. The incidence of transient mild retinal photochemical injuries without permanent fundus lesions that caused temporary visual disturbances in patients has not, to our knowledge, been described in the literature. Many potential risk factors for photic retinal injury have been described. These include intensity of the light source from the operating microscope, duration of exposure, target refraction after surgery (emmetropia poses higher risk as light is accurately focused onto the retina), coexisting retinal vascular diseases such as diabetic retinopathy and retinal vein occlusion, density of cataract, lightly pigmented fundus, hydrochlorothiazide use, and vitamin A and ascorbic acid deficiency.5 Michael and Wegener3 provide an estimate of the safe exposure times to avoid retinal photochemical injury using the Zeiss operating microscope Opmi Visu 200 (maximum light intensity, worst-case conditions, and including a safety factor) according to the American Conference for Governmental and Industrial Hygienists guidelines. They describe safe
exposure duration of 3 minutes when no filter is used, although this can be significantly prolonged to 49 minutes when UV radiation and combination filters for other wavelengths are used. In conclusion, we agree with Dr. Tengroth that surgeons should recognize the possibility of photic retinal injury from operating microscopes during cataract extraction surgery and take steps to reduce its occurrence. During preoperative counseling, patients should be informed of the risk for photic retinal injury to prepare them for possible visual disturbances after cataract surgery. Wei Kiong Ngo, MB BS Colin S. Tan, MB BS, FRCSEd(Ophth), MMed (Ophth) Singapore Dr. Tan receives travel support from Bayer HealthCare AG, Heidelberg Engineering GmbH, and Novartis Corp. He also receives research support from the National Healthcare Group Clinician Scientist Career Scheme Grant (CSCS/12005). REFERENCES 1. Tengroth BM. Visual experience of the cataract patient after surgery [letter]. J Cataract Refract Surg 2014; 40:1250–1251 2. Ang C-L, Au Eong KG, Lee SSG, Chan SP, Tan CSH. Patients’ expectation and experience of visual sensations during phacoemulsification under topical anaesthesia. Eye 2007; 21:1162– 1167. Available at: http://www.nature.com/eye/journal/v21/n9/ pdf/6702427a.pdf. Accessed August 15, 2014 3. Michael R, Wegener A. Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye. J Opt Soc Am A Opt Image Sci Vis 2004; 21:1388–1392 4. Khwarg SG, Linstone FA, Daniels SA, Isenberg SJ, Hanscom TA, Geoghegan M, Straatsma BR. Incidence, risk factors, and morphology in operating microscope light retinopathy. Am J Ophthalmol 1987; 103:255–263 5. Kleinmann G, Hoffman P, Schechtman E, Pollack A. Microscope-induced retinal phototoxicity in cataract surgery of short duration. Ophthalmology 2002; 109:334–338
On devices for creating a continuous curvilinear capsulorhexis Powers and Kahook1 reported a series of experiments designed to provide a new device for creating a continuous curvilinear capsulorhexis (CCC). The 5 phases of the device iteration illustrated the logic and thought applied to the problem and the trial and error that accompanies innovations. The most successful device was a flexible, medical-grade silicone ring that was inserted and stabilized using an ophthalmic viscosurgical device (OVD) in the anterior chamber. We have been using a similar device in our institution
J CATARACT REFRACT SURG - VOL 40, OCTOBER 2014
LETTERS
Reply : Good idea. Thanks for reading our article. dThomas A. Oetting, MD
Photic retinal injury from operating microscope during cataract surgery We read Dr. Tengroth's account of his visual experience after cataract surgery1 and are relieved that this distressing situation resolved without long-term sequelae. The article highlights the importance of a patient's visual experiences during and after cataract surgery, which is an aspect of healthcare that deserves more attention from ophthalmologists. These experiences, and our patients' preoperative expectations, affect patients' overall satisfaction with the entire medical encounter.2 Dr. Tengroth reported a temporary loss of blue cone response after uneventful cataract surgery,1 which was presumed to be due to photic retinal injury after exposure to the intense light from the operating microscope during surgery. The concept of ultraviolet (UV) radiation and blue-light hazards causing retinal thermal and photochemical injury from operating microscopes has been described.3 At the more severe end of the spectrum, Khwarg et al.4 described an incidence of 7% for operating microscope light-induced retinopathy in 135 consecutive patients who had cataract surgery. These cases of light-induced retinopathy demonstrated recognizable fundus lesions that appeared as focal pigment epithelial changes and could be demonstrated on fundus fluorescein angiography as sharply demarcated transmission defects. The incidence of transient mild retinal photochemical injuries without permanent fundus lesions that caused temporary visual disturbances in patients has not, to our knowledge, been described in the literature. Many potential risk factors for photic retinal injury have been described. These include intensity of the light source from the operating microscope, duration of exposure, target refraction after surgery (emmetropia poses higher risk as light is accurately focused onto the retina), coexisting retinal vascular diseases such as diabetic retinopathy and retinal vein occlusion, density of cataract, lightly pigmented fundus, hydrochlorothiazide use, and vitamin A and ascorbic acid deficiency.5 Michael and Wegener3 provide an estimate of the safe exposure times to avoid retinal photochemical injury using the Zeiss operating microscope Opmi Visu 200 (maximum light intensity, worst-case conditions, and including a safety factor) according to the American Conference for Governmental and Industrial Hygienists guidelines. They describe safe
exposure duration of 3 minutes when no filter is used, although this can be significantly prolonged to 49 minutes when UV radiation and combination filters for other wavelengths are used. In conclusion, we agree with Dr. Tengroth that surgeons should recognize the possibility of photic retinal injury from operating microscopes during cataract extraction surgery and take steps to reduce its occurrence. During preoperative counseling, patients should be informed of the risk for photic retinal injury to prepare them for possible visual disturbances after cataract surgery. Wei Kiong Ngo, MB BS Colin S. Tan, MB BS, FRCSEd(Ophth), MMed (Ophth) Singapore Dr. Tan receives travel support from Bayer HealthCare AG, Heidelberg Engineering GmbH, and Novartis Corp. He also receives research support from the National Healthcare Group Clinician Scientist Career Scheme Grant (CSCS/12005). REFERENCES 1. Tengroth BM. Visual experience of the cataract patient after surgery [letter]. J Cataract Refract Surg 2014; 40:1250–1251 2. Ang C-L, Au Eong KG, Lee SSG, Chan SP, Tan CSH. Patients’ expectation and experience of visual sensations during phacoemulsification under topical anaesthesia. Eye 2007; 21:1162– 1167. Available at: http://www.nature.com/eye/journal/v21/n9/ pdf/6702427a.pdf. Accessed August 15, 2014 3. Michael R, Wegener A. Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye. J Opt Soc Am A Opt Image Sci Vis 2004; 21:1388–1392 4. Khwarg SG, Linstone FA, Daniels SA, Isenberg SJ, Hanscom TA, Geoghegan M, Straatsma BR. Incidence, risk factors, and morphology in operating microscope light retinopathy. Am J Ophthalmol 1987; 103:255–263 5. Kleinmann G, Hoffman P, Schechtman E, Pollack A. Microscope-induced retinal phototoxicity in cataract surgery of short duration. Ophthalmology 2002; 109:334–338
On devices for creating a continuous curvilinear capsulorhexis Powers and Kahook1 reported a series of experiments designed to provide a new device for creating a continuous curvilinear capsulorhexis (CCC). The 5 phases of the device iteration illustrated the logic and thought applied to the problem and the trial and error that accompanies innovations. The most successful device was a flexible, medical-grade silicone ring that was inserted and stabilized using an ophthalmic viscosurgical device (OVD) in the anterior chamber. We have been using a similar device in our institution
J CATARACT REFRACT SURG - VOL 40, OCTOBER 2014
