Eyeworld

Effects of cataract surgery Cataract surgeons often underappre- ciate the effects of cataract surgery on refractive surfaces. Patients seeking cataract surgery are already at high risk for dry eye. They are usually older and experi- encing hormonal changes, whether they are perimenopausal women or men with reduced testosterone lev- els. Patients' systemic medications may dry the ocular surface, and their diets may be deficient in omega-3 fatty acids. There are also multiple factors that play a role before, during, and after surgery. After preoperative dilation and instillation of anesthetic drops, patients may wait as long as an hour with minimal blinking due to corneal anesthesia, resulting in ocular surface keratitis or punctate keratitis by the time they arrive in the operating room. Intraoperatively, mild corneal trauma and micro-erosions may occur, resulting from the lid speculum placement and exposure. Supported by an unrestricted educational grant from Allergan Limbal relaxing incisions and corneal sensitivity Astigmatic incisions used in refractive cataract surgery can reduce corneal sensation, further contributing to dry eye. In the CLEAR Trial by Donnenfeld et al., which analyzed the first 20 patients returning for a 3-month visit after clear corneal extraction with 2 limbal relaxing incisions (LRIs), patients had a significant reduction in Cochet-Bonnet corneal sensitivity in regions adjacent to the LRIs and center of the cornea (Table 1). 1 In this prospective, multicenter, observational trial, which included patients older than 50 years without dry eye, uncorrected visual acuity and best corrected visual acuity improved after cataract surgery and LRIs. At baseline, prior to the surgery, corneal sensation was >50 mm in all 5 regions in all eyes, but at week 1 one-fifth of patients had severely reduced corneal sensation (<25 mm). Corneal sensitivity was still reduced at 1 month, but returned to near-normal levels 3 months after surgery. Reference 1. Donnenfeld E, Holland E, Nichamin LD, et al. Multicenter prospective evaluation of effects of cataract extraction and limbal relaxing incisions on corneal sensation and dry eye (CLEAR Trial). Using conjunctival impres- sion cytology in patients who had cataract surgery, Oh et al. found a significant loss of goblet cell density that did not recover 3 months later. 6 The longer the surgery, the greater the decrease in goblet cell density. Patients' tear breakup time and corneal sensitivity also decreased at day 1 but recovered by 1 month. Benzalkonium chloride (BAK) and proparacaine in the topical anesthesia and eye drops significant- ly affect epithelial cell integrity and tear function. 7,8 Surgical incisions may disrupt corneal innervation (see sidebar) and increase the inter-blink inter- val. 9 After surgery, postoperative drops containing BAK may cause additional surface toxicity, and dry eye disease may worsen if patients decrease or stop using artificial tears. Meibomian gland dysfunction may worsen if they discontinue their warm compresses and lid hygiene. Conclusion Because the tear film is the first and most important refractive interface in the eye, surgeons need to be aware of how irregularities affect image quality. Evaporation, dry eye, long blink intervals, and perioperative factors all can worsen irregularities and vision quality. References 1. Tutt R, Bradley A, Begley C, Thibos LN. Optical and visual impact of tear break-up in human eyes. Invest Ophthalmol Vis Sci 2000;41:4117–4123. 2. Benito A, Perez, GM, Mirabet S, et al. Objective optical assessment of tear-film quality dynamics in normal and mildly symptomatic dry eyes. J Cataract Refract Surg 2011;37:1481–1487. 3. Németh J, Erdélyi B, Csákány B. Corneal topography changes after a 15 second pause in blinking. J Cataract Refract Surg 2001;27:589–592. 4. Goto E, Yagi Y, Masumoto Y, Tsubota K. Im- paired functional visual acuity of dry eye pa- tients. Am J Ophthalmol 2002;133:181–186. 5. Montés-Micó R. Role of the tear film in the optical quality of the human eye. J Cataract Refract Surg 2007;33:1631–1635. 6. Oh T, Jung Y, Chang D, et al. Changes in the tear film and ocular surface after cataract sur- gery. Jpn J Ophthalmol 2012;56(2):113–118. 7. Broadway DC, Grierson I, O'Brien C, Hitchings RA. Adverse effects of topical antiglaucoma medication. Arch Ophthalmol 1994;112:1437–1445. 8. Baudouin C, de Lunardo C. Short-term comparative study of topical 2% carteolol with and without benzalkonium chloride in healthy volunteers. Br J Ophthalmol 1998;82:39–42. 9. Kohlhaas M. Corneal sensation after cataract and refractive surgery. J Cataract Refract Surg 1998;24:1399–1409. Dr. Farid is associate professor of ophthalmology; director of cornea, cataract, and refractive surgery; and vice chair of ophthalmic faculty at the Gavin Herbert Eye Institute, University of California, Irvine. She can be contacted at mfarid@uci.edu. Table 1: LRIs and dry eye

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