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Reevaluating intracameral cefuroxime as a prophylaxis against endophthalmitis after cataract surgery
LETTERS
support the statement that posterior capsule tears “can have a significant effect on endothelial cell loss, glaucoma, cystoid macular edema, endophthalmitis, and retinal detachment when anterior vitrectomy is required and surgical time prolonged” rather than in reference to any effect of anterior or posterior capsule tears on refractive outcomes. As stated in our paper, “[t]he rate of posterior capsule tear was not significantly different between our femtosecond laser–assisted cataract surgery and phacoemulsification cataract surgery cohorts, even though the result was numerically greater in the femtosecond laser cohort.” Our calculated P value was 0.14 (c2 test) and hence reported as not statistically significant. Dr. Davidorf’s calculation at PZ.06 might highlight a trend toward significance. From our data, it is not possible to determine whether the numerical difference in posterior capsule tear rates (higher in laser–assisted cataract surgery) represents no difference between cohorts or that there was insufficient power to show a statistical difference. Although posterior capsule complications are typically more clinically significant than anterior capsule complications, we agree that anterior capsule tears can also potentially affect the positioning and choice of IOL and this can be clinically relevant to refractive outcomes. As highlighted in our paper, anterior capsule complications with laser–assisted cataract surgery remain a significant concern. We believe these represent a biomechanical weakness introduced by the femtosecond laser, which creates an ultrastructural can-opener capsulotomy.2 Our study of more than 4000 eyes found that the rate of intraoperative complications was significantly higher in the laser–assisted cataract surgery cohort, despite that many of the more challenging patients (eg, small pupils) were more likely to be included in the phacoemulsification cataract surgery cohort. Therefore, we agree with Dr. Davidorf’s conclusion that the rate of intraoperative complications is higher and hence the safety lower in femtosecond laser–assisted cataract surgery. In regard to our own conclusions, our initial submission put a stronger emphasis on these valid safety concerns.dCarmen L. Oakley, MB BS, Penelope L. Allen, PhD, Robin G. Abell, MB BS, Erica DarianSmith, MB BS, Jeffrey B. Kan, MB BS, Shaun Y. Ewe, MB BS, Brendan J. Vote, FRANZCO REFERENCES 1. Chan E, Mahroo OAR, Spalton DJ. Complications of cataract surgery. Clin Exp Optom 2010; 93:379–389. Available at: http://online library.wiley.com/doi/10.1111/j.1444-0938.2010.00516.x/pdf. Accessed March 21, 2015 2. Abell RG, Davies PEJ, Phelan D, Goemann K, McPherson ZE, Vote BJ. Anterior capsulotomy integrity after femtosecond laserassisted cataract surgery. Ophthalmology 2014; 121:17–24
1125
Reevaluating intracameral cefuroxime as a prophylaxis against endophthalmitis after cataract surgery We read with interest the article by Sharma et al.1 comparing the rates of postoperative endophthalmitis between a group of patients treated with intracameral cefuroxime after cataract surgery and one that did not receive intracameral antibiotics. Although the authors reported no significant difference in the rates of endophthalmitis, it is important to note that the overall incidence of endophthalmitis decreased from 0.155% to 0.108%, while the rate of culture-positive infections decreased from 0.09% to 0.04%. Although the decrease in the number of infected cases might not be statistically significant, we believe that this is clinically relevant and agree with the authors' conclusion that “intracameral cefuroxime could be used for prophylaxis treatment against postoperative endophthalmitis.”1 The relatively small decrease in the rate of endophthalmitis that was observed in this series might be explained, as the authors have suggested, by the fact that the rate of endophthalmitis was already fairly low in the period before intracameral antibiotics were introduced. It is also possible that if larger numbers of patients had been studied over a longer period, a more obvious difference in the rates of endophthalmitis would have become apparent. In addition to the studies cited by the authors, we would like to highlight several studies that have reported significant decreases in the rates of postoperative endophthalmitis after the use of intracameral cefazolin.2–4 This, we believe, adds to the evidence that the use of intracameral antibiotics is a useful measure to reduce the rates of infection. Although the ideal choice of antibiotic and its dosage remain topics of discussion, we believe there is sufficient evidence to support the use of intracameral antibiotics after cataract surgery. We are curious whether the authors observed differences in the rates of infection between patients having phacoemulsification or small-incision cataract surgery. An earlier study5 reported a higher rate of endophthalmitis among patients in the manual small- and largeincision extracapsular cataract extraction group than among those who had phacoemulsification. It has been suggested that a larger wound might increase the risk for endophthalmitis. Also of interest is that no cases of gram-negative cultures were reported in Group 1 (patients who did not receive intracameral cefuroxime) while 2 of 3 culturepositive cases in Group 2 (patients who received intracameral cefuroxime) were gram-negative species (Escherichia coli and Pseudomonas aeruginosa). It has been suggested that because cephalosporins are more effective against gram-positive organisms, their
J CATARACT REFRACT SURG - VOL 41, MAY 2015
1126
LETTERS
use after ocular surgery might result in a relatively higher proportion of infections by gram-negative species. The evidence in the literature is mixed,2 and no definite conclusions can be drawn at present given the very small number of endophthalmitis cases from various studies. In summary, we congratulate the authors on their results and support the view that intracameral antibiotics have an important role in reducing the rates of postoperative endophthalmitis. Colin S.H. Tan, MBBS, MMed(Ophth), FRCSEd (Ophth) Louis W. Lim, MB BS Kai Xiong Cheong, MB BS Singapore REFERENCES 1. Sharma S, Sahu SK, Dhillon V, Das S, Rath S. Reevaluating intracameral cefuroxime as a prophylaxis against endophthalmitis after cataract surgery in India. J Cataract Refract Surg 2015; 41:393–399 2. Tan CSH, Wong HK, Yang FP. Epidemiology of postoperative endophthalmitis in an Asian population: 11-year incidence and effect of intracameral antibiotic agents. J Cataract Refract Surg 2012; 38:425–430 s C, 3. Garat M, Moser CL, Martın-Baranera M, Alonso-Tarre Alvarez-Rubio L. Prophylactic intracameral cefazolin after cataract surgery; endophthalmitis risk reduction and safety results in a 6-year study. J Cataract Refract Surg 2009; 35:637–642 ndez I, Salvat M, Ferna ndez J, Almena M. Intra4. Romero P, Me cameral cefazolin as prophylaxis against endophthalmitis in cataract surgery. J Cataract Refract Surg 2006; 32:438–441 5. Ravindran RD, Venkatesh R, Chang DF, Sengupta S, Gyatsho J, Talwar B. The incidence of post-cataract endophthalmitis at an Aravind Eye Hospital; outcomes of more than 42000 consecutive cases using standardized sterilization and prophylaxis protocols. J Cataract Refract Surg 2009; 35:629–636
Myopic eyes develop cataracts at an earlier age I read with interest the paper by Iijima et al.1 regarding demographics of refractive surgery patients having cataract surgery. Their findings are novel and quite interesting. The authors note that “[e]yes with longer ALs [axial lengths] frequently are affected by cataract formation earlier than those with normal ALs.” They reference 3 papers from 1999 to 2014 but do not reference the paper that first proved this phenomenon in 1980 published in the American Journal of Ophthalmology.2 It was also confirmed in 3 subsequent publications in this journal.2–4 Also in their introduction, they reference papers regarding the problems with the predictability of intraocular lens power calculation in refractive surgery eyes but leave out the first paper pointing
out this problem in 1989 by Koch et al.5 in the American Journal of Ophthalmology, the editorial in the Archives of Ophthalmology6 in 2002, and the review in this journal7 in 2009 covering the entire subject. Kenneth J. Hoffer, MD Santa Monica, California, USA Dr. Hoffer owns the registered trademark name HofferÒ when used in commercial software products. REFERENCES 1. Iijima K, Kamiya K, Shimizu K, Igarashi A, Komatsu M. Demographics of patients having cataract surgery after laser in situ keratomileusis. J Cataract Refract Surg 2015; 41:334–338 2. Hoffer KJ. Biometry of 7,500 cataractous eyes. Am J Ophthalmol 1980; 90:360–368; correction, 89 3. Hoffer KJ. Reply to letter by Zuberbuhler B, Morrell AJ. J Cataract Refract Surg 2007; 33:2–3 4. Hoffer KJ. Clinical results using the Holladay 2 intraocular lens power formula. J Cataract Refract Surg 2000; 26:1233–1237 5. Koch DD, Liu JF, Hyde LL, Rock RL, Emery JM. Refractive complications of cataract surgery after radial keratotomy. Am J Ophthalmol 1989; 108:676–682 6. Hoffer KJ. Calculating intraocular lens power after refractive surgery [editorial]. Arch Ophthalmol 2002; 120:500–501 7. Hoffer KJ. Intraocular lens power calculation after previous laser refractive surgery. J Cataract Refract Surg 2009; 35:759–765
Reply : We appreciate the insightful comments of Dr. Hoffer on our article. We agree with his opinion that 3 earlier studies by Hoffer et al.1–3 of cataract formation with long ALs as well as 3 earlier studies by Koch et al.4 and Hoffer et al.5,6 of the problems with the predictability of IOL power calculation in postrefractive surgery eyes are important for this topic and thus should have been cited in this article. According to our experience, patient age at the time of cataract surgery in the post-laser in situ keratomileusis cataract group was significantly younger than even that in the AL-matched group.dKei Iijima, MD, Kimiya Shimizu, MD, PhD, Kazutaka Kamiya, MD, PhD, Akihito Igarashi, MD, PhD, Mari Komatsu, MD, PhD REFERENCES 1. Hoffer KJ. Biometry of 7,500 cataractous eyes. Am J Ophthalmol 1980; 90:360–368; correction, 89 2. Hoffer KJ. The Hoffer Q formula: a comparison of theoretic and regression formulas. J Cataract Refract Surg 1993; 19:700– 712; errata, 1994; 20:677 and 2007; 33:2–3 3. Hoffer KJ. Clinical results using the Holladay 2 intraocular lens power formula. J Cataract Refract Surg 2000; 26:1233– 1237 4. Koch DD, Liu JF, Hyde LL, Rock RL, Emery JM. Refractive complications of cataract surgery after radial keratotomy. Am J Ophthalmol 1989; 108:676–682
J CATARACT REFRACT SURG - VOL 41, MAY 2015
support the statement that posterior capsule tears “can have a significant effect on endothelial cell loss, glaucoma, cystoid macular edema, endophthalmitis, and retinal detachment when anterior vitrectomy is required and surgical time prolonged” rather than in reference to any effect of anterior or posterior capsule tears on refractive outcomes. As stated in our paper, “[t]he rate of posterior capsule tear was not significantly different between our femtosecond laser–assisted cataract surgery and phacoemulsification cataract surgery cohorts, even though the result was numerically greater in the femtosecond laser cohort.” Our calculated P value was 0.14 (c2 test) and hence reported as not statistically significant. Dr. Davidorf’s calculation at PZ.06 might highlight a trend toward significance. From our data, it is not possible to determine whether the numerical difference in posterior capsule tear rates (higher in laser–assisted cataract surgery) represents no difference between cohorts or that there was insufficient power to show a statistical difference. Although posterior capsule complications are typically more clinically significant than anterior capsule complications, we agree that anterior capsule tears can also potentially affect the positioning and choice of IOL and this can be clinically relevant to refractive outcomes. As highlighted in our paper, anterior capsule complications with laser–assisted cataract surgery remain a significant concern. We believe these represent a biomechanical weakness introduced by the femtosecond laser, which creates an ultrastructural can-opener capsulotomy.2 Our study of more than 4000 eyes found that the rate of intraoperative complications was significantly higher in the laser–assisted cataract surgery cohort, despite that many of the more challenging patients (eg, small pupils) were more likely to be included in the phacoemulsification cataract surgery cohort. Therefore, we agree with Dr. Davidorf’s conclusion that the rate of intraoperative complications is higher and hence the safety lower in femtosecond laser–assisted cataract surgery. In regard to our own conclusions, our initial submission put a stronger emphasis on these valid safety concerns.dCarmen L. Oakley, MB BS, Penelope L. Allen, PhD, Robin G. Abell, MB BS, Erica DarianSmith, MB BS, Jeffrey B. Kan, MB BS, Shaun Y. Ewe, MB BS, Brendan J. Vote, FRANZCO REFERENCES 1. Chan E, Mahroo OAR, Spalton DJ. Complications of cataract surgery. Clin Exp Optom 2010; 93:379–389. Available at: http://online library.wiley.com/doi/10.1111/j.1444-0938.2010.00516.x/pdf. Accessed March 21, 2015 2. Abell RG, Davies PEJ, Phelan D, Goemann K, McPherson ZE, Vote BJ. Anterior capsulotomy integrity after femtosecond laserassisted cataract surgery. Ophthalmology 2014; 121:17–24
1125
Reevaluating intracameral cefuroxime as a prophylaxis against endophthalmitis after cataract surgery We read with interest the article by Sharma et al.1 comparing the rates of postoperative endophthalmitis between a group of patients treated with intracameral cefuroxime after cataract surgery and one that did not receive intracameral antibiotics. Although the authors reported no significant difference in the rates of endophthalmitis, it is important to note that the overall incidence of endophthalmitis decreased from 0.155% to 0.108%, while the rate of culture-positive infections decreased from 0.09% to 0.04%. Although the decrease in the number of infected cases might not be statistically significant, we believe that this is clinically relevant and agree with the authors' conclusion that “intracameral cefuroxime could be used for prophylaxis treatment against postoperative endophthalmitis.”1 The relatively small decrease in the rate of endophthalmitis that was observed in this series might be explained, as the authors have suggested, by the fact that the rate of endophthalmitis was already fairly low in the period before intracameral antibiotics were introduced. It is also possible that if larger numbers of patients had been studied over a longer period, a more obvious difference in the rates of endophthalmitis would have become apparent. In addition to the studies cited by the authors, we would like to highlight several studies that have reported significant decreases in the rates of postoperative endophthalmitis after the use of intracameral cefazolin.2–4 This, we believe, adds to the evidence that the use of intracameral antibiotics is a useful measure to reduce the rates of infection. Although the ideal choice of antibiotic and its dosage remain topics of discussion, we believe there is sufficient evidence to support the use of intracameral antibiotics after cataract surgery. We are curious whether the authors observed differences in the rates of infection between patients having phacoemulsification or small-incision cataract surgery. An earlier study5 reported a higher rate of endophthalmitis among patients in the manual small- and largeincision extracapsular cataract extraction group than among those who had phacoemulsification. It has been suggested that a larger wound might increase the risk for endophthalmitis. Also of interest is that no cases of gram-negative cultures were reported in Group 1 (patients who did not receive intracameral cefuroxime) while 2 of 3 culturepositive cases in Group 2 (patients who received intracameral cefuroxime) were gram-negative species (Escherichia coli and Pseudomonas aeruginosa). It has been suggested that because cephalosporins are more effective against gram-positive organisms, their
J CATARACT REFRACT SURG - VOL 41, MAY 2015
1126
LETTERS
use after ocular surgery might result in a relatively higher proportion of infections by gram-negative species. The evidence in the literature is mixed,2 and no definite conclusions can be drawn at present given the very small number of endophthalmitis cases from various studies. In summary, we congratulate the authors on their results and support the view that intracameral antibiotics have an important role in reducing the rates of postoperative endophthalmitis. Colin S.H. Tan, MBBS, MMed(Ophth), FRCSEd (Ophth) Louis W. Lim, MB BS Kai Xiong Cheong, MB BS Singapore REFERENCES 1. Sharma S, Sahu SK, Dhillon V, Das S, Rath S. Reevaluating intracameral cefuroxime as a prophylaxis against endophthalmitis after cataract surgery in India. J Cataract Refract Surg 2015; 41:393–399 2. Tan CSH, Wong HK, Yang FP. Epidemiology of postoperative endophthalmitis in an Asian population: 11-year incidence and effect of intracameral antibiotic agents. J Cataract Refract Surg 2012; 38:425–430 s C, 3. Garat M, Moser CL, Martın-Baranera M, Alonso-Tarre Alvarez-Rubio L. Prophylactic intracameral cefazolin after cataract surgery; endophthalmitis risk reduction and safety results in a 6-year study. J Cataract Refract Surg 2009; 35:637–642 ndez I, Salvat M, Ferna ndez J, Almena M. Intra4. Romero P, Me cameral cefazolin as prophylaxis against endophthalmitis in cataract surgery. J Cataract Refract Surg 2006; 32:438–441 5. Ravindran RD, Venkatesh R, Chang DF, Sengupta S, Gyatsho J, Talwar B. The incidence of post-cataract endophthalmitis at an Aravind Eye Hospital; outcomes of more than 42000 consecutive cases using standardized sterilization and prophylaxis protocols. J Cataract Refract Surg 2009; 35:629–636
Myopic eyes develop cataracts at an earlier age I read with interest the paper by Iijima et al.1 regarding demographics of refractive surgery patients having cataract surgery. Their findings are novel and quite interesting. The authors note that “[e]yes with longer ALs [axial lengths] frequently are affected by cataract formation earlier than those with normal ALs.” They reference 3 papers from 1999 to 2014 but do not reference the paper that first proved this phenomenon in 1980 published in the American Journal of Ophthalmology.2 It was also confirmed in 3 subsequent publications in this journal.2–4 Also in their introduction, they reference papers regarding the problems with the predictability of intraocular lens power calculation in refractive surgery eyes but leave out the first paper pointing
out this problem in 1989 by Koch et al.5 in the American Journal of Ophthalmology, the editorial in the Archives of Ophthalmology6 in 2002, and the review in this journal7 in 2009 covering the entire subject. Kenneth J. Hoffer, MD Santa Monica, California, USA Dr. Hoffer owns the registered trademark name HofferÒ when used in commercial software products. REFERENCES 1. Iijima K, Kamiya K, Shimizu K, Igarashi A, Komatsu M. Demographics of patients having cataract surgery after laser in situ keratomileusis. J Cataract Refract Surg 2015; 41:334–338 2. Hoffer KJ. Biometry of 7,500 cataractous eyes. Am J Ophthalmol 1980; 90:360–368; correction, 89 3. Hoffer KJ. Reply to letter by Zuberbuhler B, Morrell AJ. J Cataract Refract Surg 2007; 33:2–3 4. Hoffer KJ. Clinical results using the Holladay 2 intraocular lens power formula. J Cataract Refract Surg 2000; 26:1233–1237 5. Koch DD, Liu JF, Hyde LL, Rock RL, Emery JM. Refractive complications of cataract surgery after radial keratotomy. Am J Ophthalmol 1989; 108:676–682 6. Hoffer KJ. Calculating intraocular lens power after refractive surgery [editorial]. Arch Ophthalmol 2002; 120:500–501 7. Hoffer KJ. Intraocular lens power calculation after previous laser refractive surgery. J Cataract Refract Surg 2009; 35:759–765
Reply : We appreciate the insightful comments of Dr. Hoffer on our article. We agree with his opinion that 3 earlier studies by Hoffer et al.1–3 of cataract formation with long ALs as well as 3 earlier studies by Koch et al.4 and Hoffer et al.5,6 of the problems with the predictability of IOL power calculation in postrefractive surgery eyes are important for this topic and thus should have been cited in this article. According to our experience, patient age at the time of cataract surgery in the post-laser in situ keratomileusis cataract group was significantly younger than even that in the AL-matched group.dKei Iijima, MD, Kimiya Shimizu, MD, PhD, Kazutaka Kamiya, MD, PhD, Akihito Igarashi, MD, PhD, Mari Komatsu, MD, PhD REFERENCES 1. Hoffer KJ. Biometry of 7,500 cataractous eyes. Am J Ophthalmol 1980; 90:360–368; correction, 89 2. Hoffer KJ. The Hoffer Q formula: a comparison of theoretic and regression formulas. J Cataract Refract Surg 1993; 19:700– 712; errata, 1994; 20:677 and 2007; 33:2–3 3. Hoffer KJ. Clinical results using the Holladay 2 intraocular lens power formula. J Cataract Refract Surg 2000; 26:1233– 1237 4. Koch DD, Liu JF, Hyde LL, Rock RL, Emery JM. Refractive complications of cataract surgery after radial keratotomy. Am J Ophthalmol 1989; 108:676–682
J CATARACT REFRACT SURG - VOL 41, MAY 2015