Photic retinal injury from operating microscope during cataract surgery.

Abstract

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.