CORRESPONDENCE
Table 1. Differences in ocular response analyzer readings between nonsmokers and smokers. Mean (mm Hg) G SD Parameter Goldmann-correlated IOP Cornea-compensated IOP Corneal resistance factor
Nonsmokers (n Z 66)
Smokers (n Z 61)
P Value
16.3 G 3.6 16.2 G 3.4 11.1 G 1.8
18.7 G 3.6 18.1 G 3.9 11.8 G 1.5
.003* .002* .006*
IOP Z intraocular pressure *Statistically significant (P!.05, Student t test)
years. Only healthy subjects not taking systemic medication were included in the study. Nonsmokers were defined as those who had never smoked. Chronic smokers showed significant increases in the corneal resistance factor (CRF) and corneal hysteresis (CH) values. This increase in corneal stiffness might originate from compounds found in cigarette smoke that enhance corneal biomechanics; for example, formaldehyde crosslinks the cornea and experimentally increases the tissue’s resistance to collagenases.3,4 The dynamic bidirectional applanation device also measures IOP, and it compensates the measured IOP (Goldmann-correlated IOP) for corneal thickness (corneal-compensated IOP). To determine a potential relationship between chronic smoking and IOP, we continued and extended our initial study (66 eyes of nonsmokers and 61 age-matched eyes of chronic smokers). Patient ages ranged from 20 to 71 years. The nonsmokers had a mean age of 45.8 years and a median age of 46.2 years. Smokers had a mean age of 44.9 years and a median age 43.9 years. Patients were recruited at the Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland. Institutional review board approval was obtained from the Ethical Committee of the Canton of Zurich. Univariable and multivariable analyses were performed for factors related to IOP and to adjust for potential correlations. Because measurements in both eyes of the same subject are likely to correlate, generalized estimating equations with robust standard errors (Huber-White sandwich variance estimator) were used to account for the fact that both eyes of an individual were included in the analysis. Data analysis was performed using the Student t test. In smokers, there were statistically significant increases and distinct increases (O2 mm Hg) in not only the Goldmann-correlated IOP but also in the corneal-compensated IOP (P Z .0003 and P Z .002, respectively) (Table 1). The CRF showed an increase similar to the one observed previously.5 When adjusting for age, smoking status, CH, CRF, and corneal thickness, smoking had a statistically significant correlation with
683
the Goldmann-correlated IOP (R2 Z 1.925, PZ.034) and corneal-compensated IOP (R2 Z 1.655, P Z .034). This finding might indicate that the increase in IOP in smokers is independent of the previously reported increase in biomechanical resistance.5 One possible mechanism is an elevation in choroidal thickness caused by chronic smoking, which in return can cause an elevation in the episcleral venous pressure and IOP.6,7 We found a higher mean IOP in chronic long-term smokers than in nonsmokers. This increase seems to be independent of corneal biomechanical properties and of variations in central corneal thickness (CCT) because the corneal-compensated IOP has been repeatedly shown to independent of the CCT.8 In light of an estimated 1.2 billion smokers worldwide in 2010, more extensive studies are needed to further investigate this relationship. REFERENCES 1. Lee AJ, Rochtchina E, Wang JJ, Healey PR, Mitchell P. Does smoking affect intraocular pressure? Findings from the Blue Mountains Eye Study. J Glaucoma 2003; 12:209–212 2. Mehra KS, Roy PN, Khare BB. Tobacco smoking and glaucoma. Ann Ophthalmol 1976; 8:462–464 3. Madhukumar E, Vijayammal PL. Influence of cigarette smoke on cross-linking of dermal collagen. Indian J Exp Biol 1997; 35:483–486 4. Wollensak G, Spoerl E. Collagen crosslinking of human and porcine sclera. J Cataract Refract Surg 2004; 30:689–695 5. Hafezi F. Smoking and corneal biomechanics (letter). Ophthalmology 2009; 116:2259–2259.e1 6. Mansouri K, Medeiros FA, Marchase N, Tatham AJ, Auerbach D, Weinreb RN. Assessment of choroidal thickness and volume during the water drinking test by swept-source optical coherence tomography. Ophthalmology 2013; 120:2508–2516 € C‚elebi S. Effect of smoking on choroidal an U, 7. Ulas‚ F, C‚elik F, Dog thickness in healthy smokers. Curr Eye Res 2014; 39:504–511 8. Sample PA, Medeiros FA, Racette L, Pascual JP, Boden C, Zangwill LM, Bowd C, Weinreb RN. Identifying glaucomatous vision loss with visual-function–specific perimetry in the diagnostic innovations in glaucoma study. Invest Ophthalmol Vis Sci 2006; 47:3381–3389. Available at: http://www.iovs.org/ content/47/8/3381.full.pdf. Accessed November 6, 2014
Incidence of cystoid macular edema: Femtosecond laser–assisted cataract surgery versus manual cataract surgery Lewis Levitz, MBBCh, FCS(SA) Ophth, FRCSEd, FRANZCO, Joseph Reich, MBBS, DO (Melb), FRACS, FRANZCO, Timothy V. Roberts, MB BS, MMed (Syd), FRANZCO, FRACS, Michael Lawless, MB BS, FRANZCO, FRACS One of the reported benefits of femtosecond laser– assisted cataract surgery has been the significant decrease in effective phacoemulsification time and cumulative dissipated energy that can be achieved by
J CATARACT REFRACT SURG - VOL 41, MARCH 2015
684
CORRESPONDENCE
Table 1. Cases of clinical CME and associated risk factors. Patient Parameter Surgery date Surgery type Age (y) Medical history Ocular history Periop med CDVA Preop 1 wk postop 1 mo postop Final CMT (mm) Preop 1 mo postop 2 mo postop FU (mo)
1a
1b
11/2011
12/2011 Manual 72 IHD, CABG d Voltaren
20/30 20/30 20/60 20/25
20/20 20/60 20/80 20/25
305 547 516 5
291 482 602 6
2
3a
12/2011 Manual 80 d d
7/2012
20/40 20/40 20/120 20/20 NA 426 347 2
3b
8/2012 LCS 86 d Mild bilateral ERM
4
5
4/2013 Manual 58 IHD, infarct Glaucoma
5/2013 LCS 72 d d
20/40 20/60 20/40 20/20
20/25 20/60 20/40 20/25
20/20 20/16 20/40 20/20
20/30 20/25 20/40 20/20
248 382 382 20
316 456 544 22
255 412 412 24
257 462 268 5
Acular Z ketorolac tromethamine; CABG Z coronary artery bypass surgery; CDVA Z corrected distance visual acuity; CF Z counting fingers; CMT Z central macular thickness; CVA Z cerebrovascular accident; ERM Z epiretinal membrane; FU Z follow-up; IHD Z ischemic heart disease; NA Z not available; NIDDM Z non-insulin-dependent diabetes mellitus; Voltaren Z diclofenac sodium
femtosecond laser pretreatment.1–4 The proposed benefits of the reduction in phaco energy with laserassisted cataract surgery have to be carefully weighed against the possible risk for secondary cystoid macular edema (CME) resulting from the laser energy delivered. Nagy et al.5 previously showed less subclinical macular edema using a femtosecond laser platform than when manual surgery was performed. Concerns regarding the clinical application of this study have been raised.6 In a more recent prospective randomized clinical trial of 102 patients by Conrad-Hengerer et al.,7 there were no significant differences in the occurrence of macular edema between laser-assisted cataract surgery and standard phacoemulsification. No large-scale study has compared clinical CME across laser-assisted cataract surgery patients and manual cataract surgery patients. We performed a consecutive analysis of postoperative clinical CME that developed in 15 eyes of 1390 patients having laser-assisted cataract surgery or a manual cataract procedure. The postoperative safety outcomes of patients having either type of surgery performed by the same surgeon (L.L.) between January 2011 and August 2014 were prospectively collected and analyzed. All postoperative patients whose vision had not improved or had decreased at the 4-week postoperative review had optical coherence tomography (OCT) testing to confirm CME. This was repeated on all patients at the 8-week visit. The same OCT unit (Spectral Domain Cirrus, Carl Zeiss Meditec AG) was used in all cases. The preoperative baseline OCT was
available for comparison in 14 of the 15 reported eyes. In cases of CME, possible contributing factors and the time to resolution were also recorded. The femtosecond laser (LenSx, Alcon) was introduced to the practice in July 2012. All patients offered cataract surgery were then offered femtosecond laser– assisted cataract surgery. Patients were told that laserassisted cataract surgery involved new technology and had become a preferred part of the surgeon’s operating technique. The patients then proceeded to the bookings clerk to discuss the additional fees involved and were free to decide on either approach. The surgeon was not made aware of the patient’s choice until the list was prepared the day before surgery. The patients’ decisions appeared to be based on financial considerations alone because no pressure was placed on them to decide either way. Manual cases before the introduction of laser-assisted cataract surgery were included in the analysis and represent the initial cataract procedures by the surgeon at the practice. Independent-samples t tests (SPSS, version 22, International Business Machines Corp. Chicago, IL) were used to compare the incidence between groups. Clinical CME was confirmed postoperatively in 7 (0.98%) of 713 eyes in the manual surgery group and 8 (1.18%) of 677 eyes in the laser-assisted surgery group; the difference was not statistically significant (P Z .680). Table 1 shows the details of all CME patients. Follow-up ranged from 2 to 24 months, with the shortest follow-up representing complete resolution of the CME in the respective cases. Thirteen of
J CATARACT REFRACT SURG - VOL 41, MARCH 2015
685
CORRESPONDENCE
Table 1. (Cont.) Patient 6a
6b
8/2013
4/2014 LCS 72 Dyslipidemia d Acular
20/25 20/25 20/30 20/20 294 653 317 2
20/120 20/30 20/80 20/20 283 430 302 10
7
8
9
10a
10/2013 LCS 64 d d Acular
5/2013 LCS 71 d Uveitis d
8/2013 LCS 69 CABG stent ERM d
1/2014
20/40 20/20 20/60 20/20
CF 20/30 20/40 20/30
234 540 279 4
275 375 375 9
15 eyes had a final corrected distance visual acuity of better than 20/25. Several patients had recognized potential ocular or systemic risk factors for CME, including preexisting epiretinal membranes, documented central retinal vein occlusion, diabetic retinopathy, previous episodes of posterior uveitis, and significant ischemic heart disease. Two patients in each cohort developed bilateral CME, highlighting the increased risk profile of the preexisting conditions. Postoperative ketorolac tromethamine (Acular 0.5%) was introduced in June 2012 as per the practice’s day-surgery guidelines. Six eyes (4 patients) had clinical CME despite the confirmation of postoperative nonsteroidal antiinflammatory drugs. In February 2013, a new patient interface was introduced (Softfit PI, Alcon Surgical, Inc.). There was no difference in the incidence of clinical CME between before the use of the new interface and after its introduction in laser-assisted cataract surgery cases (P Z .663). Cystoid macular edema is a relatively rare complication of cataract surgery with a published incidence of between 0.1% and 2.35%.8 The pathogenesis of CME after cataract surgery remains unclear. Pseudophakic CME has variously been attributed to inflammation, vitreous traction, vascular instability, relative ocular hypotony during surgery, and ultraviolet radiation.9 The introduction of laser-assisted cataract surgery is increasingly being used by surgeons who want to decrease the amount of intraocular manipulation during cataract surgery. Early studies1,5,7 have shown that the femtosecond laser does not appear to increase
20/40 20/20 20/120 20/20 322 379 538 2
10b
4/2014 Manual 82 NIDDM, CVA Bilateral ERM Acular
11 5/2014 Manual 78 CVA ERM Acular
20/60 20/60 20/60 20/80
20/40 20/50 20/40 20/30
20/40 20/25 20/40 20/25
394 615 656 4
365 417 803 7
388 405 405 4
macular thickening or CME more than conventional cataract surgery. These reported studies, however, were limited by their size. Our results on the incidence of pseudophakic clinical CME remain consistent with those in the published literature. We found no statistically significant difference between prospective cohorts having laser-assisted cataract surgery or conventional cataract surgery. We also found no difference between laser-assisted cataract surgery patients with 2 different docking procedures. The majority of patients in both cohorts had preexisting risk factors, which suggests these patients will remain at elevated risk regardless of the surgical technique or perioperative prophylactic regimens used. Our preliminary findings in a prospective singlesurgeon study suggest the introduction of femtosecond laser–assisted cataract surgery does not change the incidence of CME. Financial Disclosure: Dr. Lawless is a member of the Alcon LenSx Medical Advisory Board. REFERENCES 1. Conrad-Hengerer I, Hengerer FH, Schultz T, Dick HB. Effect of femtosecond laser fragmentation on effective phacoemulsification time in cataract surgery. J Refract Surg 2012; 28:879–883 2. Nagy Z, Takacs A, Filkorn T, Sarayba M. Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery. J Refract Surg 2009; 25:1053–1060 3. Abell RG, Kerr NM, Vote BJ. Toward zero effective phacoemulsification time using femtosecond laser pretreatment. Ophthalmology 2013; 120:942–948
J CATARACT REFRACT SURG - VOL 41, MARCH 2015
686
CORRESPONDENCE
4. Palanker DV, Blumenkrantz MS, Andersen D, Wiltberger M, Marcellino G, Gooding P, Angeley D, Schuele G, Woodley B, Simoneau M, Friedman NJ, Seibel B, Batlle J, Feliz R, Talamo J, Culbertson W. Femtosecond laser–assisted cataract surgery with integrated optical coherence tomography. Sci Transl Med 2010; 2:58ra85. Available at: http://www.stanford. edu/wpalanker/publications/fs_laser_cataract.pdf. Accessed November 20, 2014 Ta cs I, Taka cs A, trai E, Somfai GM, 5. Nagy ZZ, Ecsedy M, Kova Cabrera DeBuc D. Macular morphology assessed by optical coherence tomography image segmentation after femtosecond laser–assisted and standard cataract surgery. J Cataract Refract Surg 2012; 38:941–946 6. Lauschke JL, Amjadi S, Lau OCF, Parker RT, Chui J, Win S, Sim BWC, Ku JJY, Lim CHL, Singh R, Aggarwala A, Wei MC, Cohn GS, Chan DG, Armstrong PA, Agar A, Francis IC.
Comparison of macular morphology between femtosecond laser–assisted and traditional cataract surgery [letter]. J Cataract Refract Surg 2013; 39:656–657; reply by ZZ Nagy, M Ecsedy, I Taka cs, AI cs, E Ta trai, GM Somfai, D Cabrera DeBuc, Kova 657–659 7. Conrad-Hengerer I, Hengerer FH, Al Juburi M, Schultz T, Dick HB. Femtosecond laser-induced macular changes and anterior segment inflammation in cataract surgery. J Refract Surg 2014; 30:222–226 8. Loewenstein A, Zur D. Postsurgical cystoid macular edema. Dev Ophthalmol 2010; 47:148–159 9. Flach AJ. The incidence, pathogenesis and treatment of cystoid macular edema following cataract surgery. Trans Am Ophthalmol Soc 1998; 96:557–634. Available at: http://www.pubmed central.nih.gov/picrender.fcgi?artidZ1298410&blobtypeZpdf. Accessed November 20, 2014
J CATARACT REFRACT SURG - VOL 41, MARCH 2015
Table 1. Differences in ocular response analyzer readings between nonsmokers and smokers. Mean (mm Hg) G SD Parameter Goldmann-correlated IOP Cornea-compensated IOP Corneal resistance factor
Nonsmokers (n Z 66)
Smokers (n Z 61)
P Value
16.3 G 3.6 16.2 G 3.4 11.1 G 1.8
18.7 G 3.6 18.1 G 3.9 11.8 G 1.5
.003* .002* .006*
IOP Z intraocular pressure *Statistically significant (P!.05, Student t test)
years. Only healthy subjects not taking systemic medication were included in the study. Nonsmokers were defined as those who had never smoked. Chronic smokers showed significant increases in the corneal resistance factor (CRF) and corneal hysteresis (CH) values. This increase in corneal stiffness might originate from compounds found in cigarette smoke that enhance corneal biomechanics; for example, formaldehyde crosslinks the cornea and experimentally increases the tissue’s resistance to collagenases.3,4 The dynamic bidirectional applanation device also measures IOP, and it compensates the measured IOP (Goldmann-correlated IOP) for corneal thickness (corneal-compensated IOP). To determine a potential relationship between chronic smoking and IOP, we continued and extended our initial study (66 eyes of nonsmokers and 61 age-matched eyes of chronic smokers). Patient ages ranged from 20 to 71 years. The nonsmokers had a mean age of 45.8 years and a median age of 46.2 years. Smokers had a mean age of 44.9 years and a median age 43.9 years. Patients were recruited at the Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland. Institutional review board approval was obtained from the Ethical Committee of the Canton of Zurich. Univariable and multivariable analyses were performed for factors related to IOP and to adjust for potential correlations. Because measurements in both eyes of the same subject are likely to correlate, generalized estimating equations with robust standard errors (Huber-White sandwich variance estimator) were used to account for the fact that both eyes of an individual were included in the analysis. Data analysis was performed using the Student t test. In smokers, there were statistically significant increases and distinct increases (O2 mm Hg) in not only the Goldmann-correlated IOP but also in the corneal-compensated IOP (P Z .0003 and P Z .002, respectively) (Table 1). The CRF showed an increase similar to the one observed previously.5 When adjusting for age, smoking status, CH, CRF, and corneal thickness, smoking had a statistically significant correlation with
683
the Goldmann-correlated IOP (R2 Z 1.925, PZ.034) and corneal-compensated IOP (R2 Z 1.655, P Z .034). This finding might indicate that the increase in IOP in smokers is independent of the previously reported increase in biomechanical resistance.5 One possible mechanism is an elevation in choroidal thickness caused by chronic smoking, which in return can cause an elevation in the episcleral venous pressure and IOP.6,7 We found a higher mean IOP in chronic long-term smokers than in nonsmokers. This increase seems to be independent of corneal biomechanical properties and of variations in central corneal thickness (CCT) because the corneal-compensated IOP has been repeatedly shown to independent of the CCT.8 In light of an estimated 1.2 billion smokers worldwide in 2010, more extensive studies are needed to further investigate this relationship. REFERENCES 1. Lee AJ, Rochtchina E, Wang JJ, Healey PR, Mitchell P. Does smoking affect intraocular pressure? Findings from the Blue Mountains Eye Study. J Glaucoma 2003; 12:209–212 2. Mehra KS, Roy PN, Khare BB. Tobacco smoking and glaucoma. Ann Ophthalmol 1976; 8:462–464 3. Madhukumar E, Vijayammal PL. Influence of cigarette smoke on cross-linking of dermal collagen. Indian J Exp Biol 1997; 35:483–486 4. Wollensak G, Spoerl E. Collagen crosslinking of human and porcine sclera. J Cataract Refract Surg 2004; 30:689–695 5. Hafezi F. Smoking and corneal biomechanics (letter). Ophthalmology 2009; 116:2259–2259.e1 6. Mansouri K, Medeiros FA, Marchase N, Tatham AJ, Auerbach D, Weinreb RN. Assessment of choroidal thickness and volume during the water drinking test by swept-source optical coherence tomography. Ophthalmology 2013; 120:2508–2516 € C‚elebi S. Effect of smoking on choroidal an U, 7. Ulas‚ F, C‚elik F, Dog thickness in healthy smokers. Curr Eye Res 2014; 39:504–511 8. Sample PA, Medeiros FA, Racette L, Pascual JP, Boden C, Zangwill LM, Bowd C, Weinreb RN. Identifying glaucomatous vision loss with visual-function–specific perimetry in the diagnostic innovations in glaucoma study. Invest Ophthalmol Vis Sci 2006; 47:3381–3389. Available at: http://www.iovs.org/ content/47/8/3381.full.pdf. Accessed November 6, 2014
Incidence of cystoid macular edema: Femtosecond laser–assisted cataract surgery versus manual cataract surgery Lewis Levitz, MBBCh, FCS(SA) Ophth, FRCSEd, FRANZCO, Joseph Reich, MBBS, DO (Melb), FRACS, FRANZCO, Timothy V. Roberts, MB BS, MMed (Syd), FRANZCO, FRACS, Michael Lawless, MB BS, FRANZCO, FRACS One of the reported benefits of femtosecond laser– assisted cataract surgery has been the significant decrease in effective phacoemulsification time and cumulative dissipated energy that can be achieved by
J CATARACT REFRACT SURG - VOL 41, MARCH 2015
684
CORRESPONDENCE
Table 1. Cases of clinical CME and associated risk factors. Patient Parameter Surgery date Surgery type Age (y) Medical history Ocular history Periop med CDVA Preop 1 wk postop 1 mo postop Final CMT (mm) Preop 1 mo postop 2 mo postop FU (mo)
1a
1b
11/2011
12/2011 Manual 72 IHD, CABG d Voltaren
20/30 20/30 20/60 20/25
20/20 20/60 20/80 20/25
305 547 516 5
291 482 602 6
2
3a
12/2011 Manual 80 d d
7/2012
20/40 20/40 20/120 20/20 NA 426 347 2
3b
8/2012 LCS 86 d Mild bilateral ERM
4
5
4/2013 Manual 58 IHD, infarct Glaucoma
5/2013 LCS 72 d d
20/40 20/60 20/40 20/20
20/25 20/60 20/40 20/25
20/20 20/16 20/40 20/20
20/30 20/25 20/40 20/20
248 382 382 20
316 456 544 22
255 412 412 24
257 462 268 5
Acular Z ketorolac tromethamine; CABG Z coronary artery bypass surgery; CDVA Z corrected distance visual acuity; CF Z counting fingers; CMT Z central macular thickness; CVA Z cerebrovascular accident; ERM Z epiretinal membrane; FU Z follow-up; IHD Z ischemic heart disease; NA Z not available; NIDDM Z non-insulin-dependent diabetes mellitus; Voltaren Z diclofenac sodium
femtosecond laser pretreatment.1–4 The proposed benefits of the reduction in phaco energy with laserassisted cataract surgery have to be carefully weighed against the possible risk for secondary cystoid macular edema (CME) resulting from the laser energy delivered. Nagy et al.5 previously showed less subclinical macular edema using a femtosecond laser platform than when manual surgery was performed. Concerns regarding the clinical application of this study have been raised.6 In a more recent prospective randomized clinical trial of 102 patients by Conrad-Hengerer et al.,7 there were no significant differences in the occurrence of macular edema between laser-assisted cataract surgery and standard phacoemulsification. No large-scale study has compared clinical CME across laser-assisted cataract surgery patients and manual cataract surgery patients. We performed a consecutive analysis of postoperative clinical CME that developed in 15 eyes of 1390 patients having laser-assisted cataract surgery or a manual cataract procedure. The postoperative safety outcomes of patients having either type of surgery performed by the same surgeon (L.L.) between January 2011 and August 2014 were prospectively collected and analyzed. All postoperative patients whose vision had not improved or had decreased at the 4-week postoperative review had optical coherence tomography (OCT) testing to confirm CME. This was repeated on all patients at the 8-week visit. The same OCT unit (Spectral Domain Cirrus, Carl Zeiss Meditec AG) was used in all cases. The preoperative baseline OCT was
available for comparison in 14 of the 15 reported eyes. In cases of CME, possible contributing factors and the time to resolution were also recorded. The femtosecond laser (LenSx, Alcon) was introduced to the practice in July 2012. All patients offered cataract surgery were then offered femtosecond laser– assisted cataract surgery. Patients were told that laserassisted cataract surgery involved new technology and had become a preferred part of the surgeon’s operating technique. The patients then proceeded to the bookings clerk to discuss the additional fees involved and were free to decide on either approach. The surgeon was not made aware of the patient’s choice until the list was prepared the day before surgery. The patients’ decisions appeared to be based on financial considerations alone because no pressure was placed on them to decide either way. Manual cases before the introduction of laser-assisted cataract surgery were included in the analysis and represent the initial cataract procedures by the surgeon at the practice. Independent-samples t tests (SPSS, version 22, International Business Machines Corp. Chicago, IL) were used to compare the incidence between groups. Clinical CME was confirmed postoperatively in 7 (0.98%) of 713 eyes in the manual surgery group and 8 (1.18%) of 677 eyes in the laser-assisted surgery group; the difference was not statistically significant (P Z .680). Table 1 shows the details of all CME patients. Follow-up ranged from 2 to 24 months, with the shortest follow-up representing complete resolution of the CME in the respective cases. Thirteen of
J CATARACT REFRACT SURG - VOL 41, MARCH 2015
685
CORRESPONDENCE
Table 1. (Cont.) Patient 6a
6b
8/2013
4/2014 LCS 72 Dyslipidemia d Acular
20/25 20/25 20/30 20/20 294 653 317 2
20/120 20/30 20/80 20/20 283 430 302 10
7
8
9
10a
10/2013 LCS 64 d d Acular
5/2013 LCS 71 d Uveitis d
8/2013 LCS 69 CABG stent ERM d
1/2014
20/40 20/20 20/60 20/20
CF 20/30 20/40 20/30
234 540 279 4
275 375 375 9
15 eyes had a final corrected distance visual acuity of better than 20/25. Several patients had recognized potential ocular or systemic risk factors for CME, including preexisting epiretinal membranes, documented central retinal vein occlusion, diabetic retinopathy, previous episodes of posterior uveitis, and significant ischemic heart disease. Two patients in each cohort developed bilateral CME, highlighting the increased risk profile of the preexisting conditions. Postoperative ketorolac tromethamine (Acular 0.5%) was introduced in June 2012 as per the practice’s day-surgery guidelines. Six eyes (4 patients) had clinical CME despite the confirmation of postoperative nonsteroidal antiinflammatory drugs. In February 2013, a new patient interface was introduced (Softfit PI, Alcon Surgical, Inc.). There was no difference in the incidence of clinical CME between before the use of the new interface and after its introduction in laser-assisted cataract surgery cases (P Z .663). Cystoid macular edema is a relatively rare complication of cataract surgery with a published incidence of between 0.1% and 2.35%.8 The pathogenesis of CME after cataract surgery remains unclear. Pseudophakic CME has variously been attributed to inflammation, vitreous traction, vascular instability, relative ocular hypotony during surgery, and ultraviolet radiation.9 The introduction of laser-assisted cataract surgery is increasingly being used by surgeons who want to decrease the amount of intraocular manipulation during cataract surgery. Early studies1,5,7 have shown that the femtosecond laser does not appear to increase
20/40 20/20 20/120 20/20 322 379 538 2
10b
4/2014 Manual 82 NIDDM, CVA Bilateral ERM Acular
11 5/2014 Manual 78 CVA ERM Acular
20/60 20/60 20/60 20/80
20/40 20/50 20/40 20/30
20/40 20/25 20/40 20/25
394 615 656 4
365 417 803 7
388 405 405 4
macular thickening or CME more than conventional cataract surgery. These reported studies, however, were limited by their size. Our results on the incidence of pseudophakic clinical CME remain consistent with those in the published literature. We found no statistically significant difference between prospective cohorts having laser-assisted cataract surgery or conventional cataract surgery. We also found no difference between laser-assisted cataract surgery patients with 2 different docking procedures. The majority of patients in both cohorts had preexisting risk factors, which suggests these patients will remain at elevated risk regardless of the surgical technique or perioperative prophylactic regimens used. Our preliminary findings in a prospective singlesurgeon study suggest the introduction of femtosecond laser–assisted cataract surgery does not change the incidence of CME. Financial Disclosure: Dr. Lawless is a member of the Alcon LenSx Medical Advisory Board. REFERENCES 1. Conrad-Hengerer I, Hengerer FH, Schultz T, Dick HB. Effect of femtosecond laser fragmentation on effective phacoemulsification time in cataract surgery. J Refract Surg 2012; 28:879–883 2. Nagy Z, Takacs A, Filkorn T, Sarayba M. Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery. J Refract Surg 2009; 25:1053–1060 3. Abell RG, Kerr NM, Vote BJ. Toward zero effective phacoemulsification time using femtosecond laser pretreatment. Ophthalmology 2013; 120:942–948
J CATARACT REFRACT SURG - VOL 41, MARCH 2015
686
CORRESPONDENCE
4. Palanker DV, Blumenkrantz MS, Andersen D, Wiltberger M, Marcellino G, Gooding P, Angeley D, Schuele G, Woodley B, Simoneau M, Friedman NJ, Seibel B, Batlle J, Feliz R, Talamo J, Culbertson W. Femtosecond laser–assisted cataract surgery with integrated optical coherence tomography. Sci Transl Med 2010; 2:58ra85. Available at: http://www.stanford. edu/wpalanker/publications/fs_laser_cataract.pdf. Accessed November 20, 2014 Ta cs I, Taka cs A, trai E, Somfai GM, 5. Nagy ZZ, Ecsedy M, Kova Cabrera DeBuc D. Macular morphology assessed by optical coherence tomography image segmentation after femtosecond laser–assisted and standard cataract surgery. J Cataract Refract Surg 2012; 38:941–946 6. Lauschke JL, Amjadi S, Lau OCF, Parker RT, Chui J, Win S, Sim BWC, Ku JJY, Lim CHL, Singh R, Aggarwala A, Wei MC, Cohn GS, Chan DG, Armstrong PA, Agar A, Francis IC.
Comparison of macular morphology between femtosecond laser–assisted and traditional cataract surgery [letter]. J Cataract Refract Surg 2013; 39:656–657; reply by ZZ Nagy, M Ecsedy, I Taka cs, AI cs, E Ta trai, GM Somfai, D Cabrera DeBuc, Kova 657–659 7. Conrad-Hengerer I, Hengerer FH, Al Juburi M, Schultz T, Dick HB. Femtosecond laser-induced macular changes and anterior segment inflammation in cataract surgery. J Refract Surg 2014; 30:222–226 8. Loewenstein A, Zur D. Postsurgical cystoid macular edema. Dev Ophthalmol 2010; 47:148–159 9. Flach AJ. The incidence, pathogenesis and treatment of cystoid macular edema following cataract surgery. Trans Am Ophthalmol Soc 1998; 96:557–634. Available at: http://www.pubmed central.nih.gov/picrender.fcgi?artidZ1298410&blobtypeZpdf. Accessed November 20, 2014
J CATARACT REFRACT SURG - VOL 41, MARCH 2015
