Abstract
Purpose
To identify risk factors for intraoperative vitreous complications in resident-performed phacoemulsification surgery
Setting
2 urban public county hospitals
Methods
A retrospective review of phacoemulsification cataract surgeries performed by residents between January 4, 2005, and January 8, 2008
Results
Of 2434 cases meeting inclusion criteria there were 92 vitreous complications (3.8%). Significant preoperative risk factors for vitreous complications on univariate analysis included older age (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01–1.05; P=0.020), worse preoperative best corrected visual acuity (BCVA) (OR, 1.5; 95% CI, 1.1–2.0; P=0.007), left eye (OR, 1.6; 95% CI, 1.0–2.4; P=0.043), history of trauma (OR, 1.8; 95% CI, 1.0–3.4; P=0.045), prior pars plana vitrectomy (OR, 2.3; 95% CI, 1.0–5.0; P=0.034), dementia (OR, 4.4; 95% CI, 1.5–12.9; P=0.020), phacodonesis (OR, 7.1; 95% CI 2.0–26.1; P=0.014), zonular dehiscence (OR, 8.8; 95% CI 4.2–18.5; P<0.0001), posterior polar cataract (OR, 7.7; 95% CI 1.6–37.2; P=0.037), white/mature cataract (OR, 2.0; 95% CI, 1.2–3.5; P=0.005), dense nuclear sclerotic cataract (OR, 2.4; 95% CI, 1.5–4.0; P=0.0006), and poor red reflex (OR, 1.9; 95% CI, 1.2–2.9; P=0.002). Factors that remained significant on multivariate analysis were older age (OR, 1.03; 95% CI, 1.01–1.05), worse preoperative BCVA (OR, 1.52; 95% CI 1.14–2.03), left eye (OR, 1.63; 95% CI, 1.05–2.51), prior pars plana vitrectomy (OR, 1.88; 95% CI 1.01–3.51), dementia (OR, 3.65; 95% CI, 1.20–11.17), and zonular dehiscence (OR, 8.55; 95% CI, 3.92–18.63).
Conclusions
Elements of the preoperative history and exam can identify patients at higher risk for intraoperative complications during resident-performed phacoemulsification surgery.
Introduction
Intraoperative vitreous complications (including vitreous prolapse, vitreous loss, and dropped nucleus) remain a significant adverse event in cataract surgery. Vitreous loss places patients at higher risk of suboptimal visual result, cystoid macular edema, retinal detachment, and endophthalmitis.1–4 The resident learning curve for phacoemulsification surgery has been described, with decreasing vitreous loss rates seen as residents gain experience.5–8 The ability to identify patients preoperatively who are at higher risk for complications would aid in appropriate case selection based on the skill level of the resident surgeon and guide surgeons in their discussion with patients of the potential risks of surgery. To this end, we retrospectively reviewed the preoperative characteristics of resident-performed phacoemulsification surgery cases.
Methods
The study was approved by the Institutional Review Board of the University of Texas Southwestern Medical Center. All cases of resident-performed phacoemulsification surgery performed at one of two urban public county hospital systems, Parkland Health and Hospital System (Dallas) or John Peter Smith Hospital (Fort Worth) between January 4, 2005, and January 8, 2008, were included and retrospectively reviewed. The main outcome was the presence or absence of intraoperative vitreous complication, defined as vitreous prolapse into the anterior chamber, vitreous loss through the wound, or dropped nucleus into the vitreous cavity. Preoperative characteristics reviewed included patient age; gender; race; laterality; presence of diabetes; use of anticoagulants, antiplatelet agents, or tamsulosin; history of ocular trauma, uveitis, glaucoma, or prior ocular surgery (including complicated or uncomplicated cataract surgery in the fellow eye); anxiety; diagnosis of dementia; claustrophobia; ability to lay flat; frontal bossing; sunken globes; best corrected visual acuity (BCVA); dilated pupil diameter; clarity of cornea; anterior chamber depth; type of cataract; density of cataract; adequacy of red reflex; presence of pseudoexfoliation syndrome; phacodonesis; zonular dehiscence; and biometry. Cases with incomplete data were excluded. BCVA was converted to logarithm of the minimum angle of resolution (log MAR) for analysis, and acuities of count fingers and hand motions were converted to log MAR1.9 and 2.3, respectively.9 To grade density of mainly nuclear and posterior subcapsular cataracts, patients with >20/50 vision were classified as mild, 20/50–20/400 as moderate, and <20/400 as dense. Phacoemulsification was performed with the Infiniti Lens Removal System (Alcon Laboratories, Inc.). A single faculty surgeon primarily staffed cases at John Peter Smith Hospital while multiple faculty staffed cases at Parkland. Second year residents only operated at John Peter Smith.
Clinical characteristics were compared between patients with and without intraoperative vitreous complications using Chi-square or Fisher’s exact test for categorical variables and two-sample t-test for continuous variables. To evaluate the strength of association, logistic regression analysis was conducted, and odds ratios with 95% confidence intervals were calculated. In multivariate data analysis, stepwise logistic regression analysis was performed to identify significant independent factors associated with vitreous complications. All analyses were performed with SAS 9.2 (SAS Institute Inc., Cary, NC).
Results
2434 cases met inclusion criteria. Surgeries were performed by 39 different residents. There were 92 (3.8%) intraoperative vitreous complications. Significant preoperative risk factors for vitreous complications on univariate analysis included older age, worse preoperative log MAR BCVA, left eye, history of trauma, prior pars plana vitrectomy, dementia, phacodonesis, zonular dehiscence, type of cataract, and poor red reflex (Tables 1, 2). When compared to mainly nuclear sclerotic cataracts, posterior polar cataracts (P=0.037) and white/mature cataracts (P=0.005) had significantly higher complication rates. Dense nuclear sclerotic cataracts had significantly higher complication rates than moderately dense nuclear sclerotic cataracts (P=0.0006). In addition, cases with prior pars plana vitrectomy were also found to have a significantly higher risk of complications when compared to cases without prior retinal surgery (P=0.034). Odds ratios for clinical characteristics are shown in Table 3.
Table 1.
Association between vitreous complications and categorical characteristics
| Characteristic | No complications (n=2342) | Complications (n=92) | P value |
|---|---|---|---|
| Hospital system | 0.668 | ||
| John Peter Smith | 711 (30%) | 26 (28%) | |
| Parkland | 1631 (70%) | 66 (72%) | |
| Level of resident surgeon | 0.363 | ||
| Second year | 396 (17%) | 13 (14%) | |
| Third year - first half of year | 984 (42%) | 45 (49%) | |
| Third year - second half of year | 992 (42%) | 34 (37%) | |
| Anesthesia | 0.973 | ||
| General | 206 (9%) | 8 (9%) | |
| Injection or topical | 2136 (91%) | 84 (91%) | |
| Gender | 0.903 | ||
| Female | 1415 (60%) | 55 (60%) | |
| Male | 927 (40%) | 37 (40%) | |
| Race | 0.097 | ||
| Black | 655 (28%) | 25 (27%) | |
| Latino | 878 (37%) | 40 (43%) | |
| White | 611 (26%) | 15 (16%) | |
| Other | 198 (8%) | 12 (13%) | |
| Diabetes | 0.757 | ||
| No | 1235 (53%) | 47 (51%) | |
| Yes | 1107 (47%) | 45 (49%) | |
| Anticoagulation | 0.580 | ||
| None | 1711 (73%) | 71 (77%) | |
| Aspirin or clopidogrel | 566 (24%) | 20 (22%) | |
| Warfarin | 57 (2%) | 1 (1%) | |
| Tamsulosin | 1.000* | ||
| No | 2323 (99%) | 92 (100%) | |
| Yes | 19 (1%) | 0 (0%) | |
| Operative eye | 0.043 | ||
| Right | 1194 (51%) | 37 (40%) | |
| Left | 1148 (49%) | 55 (60%) | |
| Hx of trauma in operative eye | 0.045 | ||
| No | 2150 (92%) | 79 (86%) | |
| Yes | 192 (8%) | 13 (14%) | |
| Hx of uveitis | 1.000* | ||
| No | 2271 (97%) | 90 (98%) | |
| Yes | 71 (3%) | 2 (2%) | |
| Hx of glaucoma | 0.351 | ||
| No | 2182 (93%) | 89 (96%) | |
| Yes | 160 (7%) | 4 (4%) | |
| Prior ocular surgery | 0.115* | ||
| None | 2134 (91%) | 79 (86%) | |
| Vitrectomy | 84 (4%) | 7 (8%) | |
| Retinal laser | 67 (3%) | 2 (2%) | |
| Other, including scleral buckle | 57 (2%) | 4 (4%) | |
| Previous cataract surgery fellow eye | 0.067 | ||
| No | 1497 (64%) | 60 (65%) | |
| Yes (uncomplicated) | 763 (32%) | 26 (28%) | |
| Yes (complicated) | 82 (4%) | 6 (7%) | |
| Anxiety | 0.441 | ||
| No | 2164 (92%) | 83 (90%) | |
| Yes | 178 (8%) | 9 (10%) | |
| Claustrophobia | 0.752 | ||
| No | 2273 (97%) | 89 (97%) | |
| Yes | 69 (3%) | 3 (3%) | |
| Dementia | 0.020* | ||
| No | 2318 (99%) | 88 (96%) | |
| Yes | 24 (1%) | 4 (4%) | |
| Can lay flat | 0.911 | ||
| Yes | 2121 (91%) | 83 (90%) | |
| No | 221 (9%) | 9 (10%) | |
| Frontal bossing | 1.000* | ||
| No | 2307 (99%) | 91 (99%) | |
| Yes | 35 (1%) | 1 (99%) | |
| Sunken globe | 1.000* | ||
| No | 2275 (97%) | 90 (98%) | |
| Yes | 67 (3%) | 2 (2%) | |
| Cornea | 0.752* | ||
| Clear | 2273 (97%) | 89 (97%) | |
| Cloudy | 69 (3%) | 3 (3%) | |
| Anterior chamber | 0.768* | ||
| Deep | 2265 (97%) | 90 (98%) | |
| Shallow | 77 (3%) | 2 (2%) | |
| Phacodonesis | 0.014 | ||
| No | 2331 (100%) | 89 (97%) | |
| Yes | 11 (0%) | 3 (3%) | |
| Zonular dehiscence | <0.0001* | ||
| No | 2310 (99%) | 82 (89%) | |
| Yes | 32 (1%) | 10 (11%) | |
| Cataract type | 0.017 | ||
| Nuclear sclerosis mainly | 1289 (55%) | 42 (46%) | |
| Anterior subcapsular mainly | 16 (1%) | 1 (1%) | |
| Cortical mainly | 109 (5%) | 6 (7%) | |
| Posteror polar | 8 (0%) | 2 (2%) | |
| Posterior subcapsular mainly | 614 (26%) | 21 (23%) | |
| White (mature) | 300 (13%) | 20 (22%) | |
| Nuclear sclerosis | 0.0006 | ||
| Moderate | 1248 (53%) | 37 (40%) | |
| Mild | 653 (28%) | 23 (25%) | |
| Dense | 441 (19%) | 32 (35%) | |
| Posterior subcapsular | 0.635 | ||
| Moderate | 693 (30%) | 23 (25%) | |
| Mild | 1322 (56%) | 55 (60%) | |
| Dense | 327 (14%) | 14 (15%) | |
| Red reflex | 0.002 | ||
| Good | 1555 (66%) | 47 (51%) | |
| Poor | 787 (34%) | 45 (49%) | |
| Pseudoexfoliation syndrome (either eye) | 0.160* | ||
| No | 2325 (99%) | 90 (98%) | |
| Yes | 17 (1%) | 2 (2%) |
P value calculated using Fisher’s exact test; the other P values calculated using chi-square test
Table 2.
Association between vitreous complications and preoperative clinical continuous characteristics
| Characteristic | No complications (n=2342) | Complications (n=92) | P value |
|---|---|---|---|
| Age (years) | 62.19±11.55 | 65.03±10.85 | 0.020 |
| Axial length (mm) | 23.54±1.26 | 23.61±1.14 | 0.637 |
| Best corrected visual acuity (log MAR) | 0.97±0.69 | 1.21±0.79 | 0.007 |
| Astigmatism power (D) | 1.09±0.93 | 1.15±0.77 | 0.444 |
| Average keratometry (D) | 43.98±1.69 | 43.94±1.49 | 0.809 |
| Pupil diameter (mm) | 7.51±1.26 | 7.63±1.05 | 0.372 |
P value calculated using two sample t-test
Table 3.
Univariate logistic regression analysis of association between vitreous complications and clinical characteristics
| Clinical characteristic | Odds Ratio (95% confidence interval) |
|---|---|
| Male vs Female | 1.0 (0.7–1.6) |
| Black vs White | 1.6 (0.8–3.0) |
| Latino vs White | 1.9 (1.0–3.4) |
| Other race vs White | 2.5 (1.1–5.4) |
| Diabetes vs Nondiabetic | 1.1 (0.7–1.6) |
| Aspirin or clopidogrel vs None | 0.9 (0.5–1.4) |
| Warfarin vs None | 0.4 (0.1–3.1) |
| Left vs Right eye | 1.6 (1.0–2.4) |
| History of trauma vs None | 1.8 (1.0–3.4) |
| History of uveitis vs None | 0.7 (0.2–2.9) |
| History of glaucoma vs None | 0.6 (0.2–1.7) |
| History of retinal laser vs No prior retinal surgery | 0.8 (0.2–3.4) |
| History of pars plana vitrectomy vs No prior retinal surgery | 2.3 (1.0–5.0) |
| History of scleral buckle vs No prior retinal surgery | 1.9 (0.7–5.4) |
| History of uncomplicated cataract surgery fellow eye vs No surgery | 0.8 (0.5–1.3) |
| History of complicated cataract surgery fellow eye vs No surgery | 1.8 (0.8–4.3) |
| Anxiety vs None | 1.3 (0.7–2.7) |
| Claustrophobia vs None | 1.1 (0.3–3.6) |
| Dementia vs None | 4.4 (1.5–12.9) |
| Frontal bossing vs None | 0.7 (0.1–5.3) |
| Sunken globe vs None | 0.8 (0.2–3.1) |
| Cloudy cornea vs Clear cornea | 1.1 (0.3–3.6) |
| Shallow anterior chamber vs Deep anterior chamber | 0.7 (0.2–2.7) |
| Phacodonesis vs None | 7.1 (2.0–26.1) |
| Zonular dehiscence vs None | 8.8 (4.2–18.5) |
| Mainly anterior subcapsular vs Mainly nuclear sclerotic cataract | 1.9 (0.2–14.8) |
| Mainly cortical vs Mainly nuclear sclerotic cataract | 1.7 (0.7–4.1) |
| Posterior polar vs Mainly nuclear sclerotic cataract | 7.7 (1.6–37.2) |
| Mainly posterior subcapsular vs Mainly nuclear sclerotic cataract | 1.0 (0.6–1.8) |
| White/mature vs Mainly nuclear sclerotic cataract | 2.0 (1.2–3.5) |
| Dense vs Moderate nuclear sclerotic cataract | 2.4 (1.5–4.0) |
| Mild vs Moderate nuclear sclerotic cataract | 1.2 (0.7–2.0) |
| Dense vs Moderate posterior subcapsular cataract | 1.0 (0.6–1.9) |
| Mild vs Moderate posterior subcapsular cataract | 0.8 (0.5–1.3) |
| Poor red reflex vs Good red reflex | 1.9 (1.2–2.9) |
| Exfoliation syndrome vs None | 2.0 (0.7–13.4) |
Multivariate data analysis using stepwise logistic regression analysis revealed older age, log MAR BCVA, left eye, prior vitrectomy surgery, dementia, and zonular dehiscence to be significant independent preoperative factors associated with vitreous complications (Table 4).
Table 4.
Independent significant preoperative characteristics for vitreous complications in stepwise logistic regression analysis
| Clinical characteristic | Odds Ratio (95% confidence interval) |
|---|---|
| Older age | 1.03 (1.01–1.05) |
| Worse best corrected visual acuity (log MAR) | 1.52 (1.14–2.03) |
| Left eye | 1.63 (1.05–2.51) |
| Prior pars plana vitrectomy | 1.88 (1.01–3.51) |
| Dementia | 3.65 (1.20–11.17) |
| Zonular dehiscence | 8.55 (3.92–18.63) |
Discussion
In this retrospective study of 2434 resident-performed phacoemusification cataract surgeries, six preoperative characteristics were found predictive of intraoperative vitreous complications on multivariate analysis. Older age has also been found to be associated with vitreous complications in other studies. Berler10 found a threefold increase in complications in phacoemulsification patients over age 88 years, while Kim et al11 found older age predictive in a multivariate analysis of 1730 resident-performed phacoemulsification surgeries. The Cataract National Dataset electronic multicenter audit of 55,567 operations in the United Kingdom also found a significant association of posterior capsule and vitreous loss with increasing age.12 We also found worse preoperative BCVA independently predictive of intraoperative vitreous complications on multivariate analysis, in contrast to Rutar et al13 in their retrospective review of 320 resident-performed phacoemulsification surgeries.
While history of trauma, phacodonesis, and zonular dehisence were significant on univariate analysis, only zonular dehiscence was significantly associated with vitreous complications on multivariate analysis. Zonular pathology is a common characteristic of all three factors. Traumatic cataracts may be associated with a higher risk of posterior capsule rupture, regardless of zonular integrity.14 The Swedish Capsule Rupture Study Group15 found an increased risk of lens capsule complications with previous trauma and phacodonesis. Rutar et al13 found an association of major intraoperative complications and zonular pathology, which they defined as antecedent trauma or pseudoexfoliation. The lack of significant association of pseudoexfoliation syndrome and vitreous complications in our study and other recent studies11,15–17 deserves comment. While the increased frequency of intraoperative complications during cataract extraction in pseudoexfoliation syndrome is usually due to zonular weakness rather than capsule tears,18 use of technique modifications and adjunctive devices appear to have decreased the risks of complications.19
Prior vitrectomy was found to be a significant risk factor for intraoperative vitreous complications on multivariate analysis in this study. Kim et al11 found prior vitrectomy a significant risk factor on univariate logistical regression analysis in their study of resident-performed phacoemulsification, but not on multivariate analysis. Cataract extraction after prior vitrectomy is often challenging and can be complicated by unstable posterior capsules, loose zonules, and posterior capsule plaques.20
To our knowledge, dementia has not been previously identified as an independent risk factor for intraoperative complications in phacoemulsification surgery. Patients with even mild dementia may become disoriented in the unfamiliar confines of the operating room or when placed under a drape. As a result of these findings, we are now more inclined to recommend general anesthesia to cataract patients with any degree of dementia.
Surprisingly, left eyes were significantly associated with complications on both univariate and multivariate analysis. This has not been found to be the case in previous series of resident-performed phacoemulsification.11,13 There were 438 bilateral cases performed in our series (876 eyes), of which vitreous complications occurred in 23 left eyes and 8 right eyes (P = 0.006, Fisher’s exact test). We can only speculate as to the cause of this finding. The vast majority of our attendings and residents are right-handed and the incisions created are temporal clear corneal. Often the right-handed attending can access the paracentesis incision at the 11 o’clock position (and even the main cataract incision comfortably with the dominant hand) of a patient’s right eye without the need to switch chairs when temporal incisions are placed by a right-handed resident. In a left eye under similar circumstances, the paracentesis incision at 5 o’clock is inaccessible from the attending sitting superiorly at the assisting port of the microscope, and the attending must switch positions with the resident in order to intervene. Perhaps attendings are more willing to intervene inside the eye if they do not have to change chairs.
Although we did not find type of cataract to be independent of age and preoperative BCVA on multivariate analysis, several types of cataract have been found to be associated with higher complication rates in previous studies. White and/or brunescent cataracts have been associated with higher rates in previous studies.12,13,15,21 Posterior polar cataracts are associated with a 26–40% risk of posterior capsule rupture during phacoemulsification.22,23 Small pupils were found to be a risk factor for intraoperative vitreous loss by Kim et al,11 but not in our study or the study by Rutar et al.13 With use of iris hooks or pupil expansion devices, residents need no longer fear the small pupil case.
Intraoperative complications decrease the probability of achieving good visual acuity postoperatively.11 By identifying cases at higher risk for complications preoperatively and assigning those surgeries to residents with more experience, hopefully visual outcomes can be optimized in training programs. Muhtaseb et al24 devised a scoring protocol to stratify cataract patients preoperatively based on risk. Similarly, Habib et al25 developed a “potential difficulty score” (PDS). Using data from experienced surgeons, a head to head comparison of the two systems validated both, with the PDS performing slightly better.14 Najjar and Awwad26 devised a cataract risk score for beginning residents that has recently been validated.27 These scoring systems were built using a combination of literature search and expert opinion. Many factors in these systems may be superfluous, while others may be missing. For example, none list dementia as a possible risk factor for complications, and only 2 of the 3 include advanced age. Najjar and Awwad purposefully excluded traumatic cataracts, congenital cataracts, polar cataracts, dislocated lenses, phacodonesis, and monocular patients from their risk score as they assumed those cases would not be given to beginning surgeons.26 A succinct, simple risk score would be of benefit to attending surgeons assigning cases to residents of differing experience and competency levels.
This study is limited by its retrospective nature. Although all data points were routinely collected during the study period, there were multiple surgeons performing the preoperative examination, with differing examination skills and evaluation bias. In addition, cases were not randomized between residents, so selection bias (assigning easier cases to less experienced residents) almost certainly exists. Second year residents operated only at John Peter Smith with primarily a single faculty surgeon. There was no significant difference found between complication rates between second and third year residents. Cataract cases are usually not as complex at John Peter Smith. In a previous review of 1833 cases,27 the Najjar-Awwad cataract surgery risk score averaged 6.79 at John Peter Smith and 6.99 at Parkland (P=0.023, unpublished data). While there was a trend towards fewer complications in the second half of the third year of residency when compared to the first half, the difference was not statistically significant (P=0.128).
In conclusion, we found several preoperative variables significantly predictive of intraoperative vitreous complications on multivariate data analysis using stepwise logistic regression. While older age, worse preoperative BCVA, prior vitrectomy surgery, and zonular dehiscence were somewhat expected from previous studies, dementia is a risk factor previously unreported to our knowledge. Laterality (with left eyes having higher risk) is an unexpected finding and deserves further investigation to see if it is unique to our institutions.
Synopsis.
2434 cases of resident-performed phacoemulsification cataract surgery were reviewed. Older age, worse preoperative vision, prior pars plana vitrectomy, dementia, and zonular dehiscence were associated with vitreous complications on multivariate analysis.
Acknowledgments
Supported in part by an unrestricted research grant from Research to Prevent Blindness, Inc., New York, New York, U.S.A. Statistical analysis was supported in part by CTSA NIH Grant UL1-RR024982. The sponsor or funding organization had no role in the design or conduct of this research.
Footnotes
Presented at the 147th Annual Meeting of the American Ophthalmological Society, Dana Point, California, May 19–22, 2011
The authors have no proprietary or financial interests to disclose. No conflicting relationship exists for any author.
Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
References
- 1.Frost NA, Sparrow JM, Strong NP, Rosenthal AR. Vitreous loss in planned extracapsular cataract extraction does lead to a poorer visual outcome. Eye. 1995;9:446–451. doi: 10.1038/eye.1995.104. [DOI] [PubMed] [Google Scholar]
- 2.Balent A, Civerchia LL, Mohamadi P. Visual outcome of cataract extraction and lens implantation complicated by vitreous loss. J Cataract Refract Surg. 1988;14:158–160. doi: 10.1016/s0886-3350(88)80089-0. [DOI] [PubMed] [Google Scholar]
- 3.Claoué C, Steele A. Visual prognosis following accidental vitreous loss during cataract surgery. Eye. 1993;7:735–739. doi: 10.1038/eye.1993.171. [DOI] [PubMed] [Google Scholar]
- 4.Javitt JC, Vitale S, Canner JK, Street DA, Krakauer H, McBean AM, Sommer A. National outcomes of cataract extraction. Endophthalmitis following inpatient surgery. Arch Ophthalmol. 1991;109:1085–1089. doi: 10.1001/archopht.1991.01080080045025. [DOI] [PubMed] [Google Scholar]
- 5.Corey RP, Olson RJ. Surgical outcomes of cataract extractions performed by residents using phacoemulsification. J Cataract Refract Surg. 1998;24:66–72. doi: 10.1016/s0886-3350(98)80076-x. [DOI] [PubMed] [Google Scholar]
- 6.Randleman JB, Srivastava SK, Aaron MM. Phacoemulsification with topical anesthesia performed by resident surgeons. J Cataract Refract Surg. 2004;30:149–154. doi: 10.1016/S0886-3350(03)00491-7. [DOI] [PubMed] [Google Scholar]
- 7.Randleman JB, Wolfe JD, Woodward M, Lynn MJ, Cherwek DH, Srivastava SK. The resident surgeon phacoemulsification learning curve. Arch Ophthalmol. 2007;125:1215–1219. doi: 10.1001/archopht.125.9.1215. [DOI] [PubMed] [Google Scholar]
- 8.Rogers GM, Oetting TA, Lee AG, Grignon C, Greenlee E, Johnson AT, Beaver HA, Carter K. Impact of a structured surgical curriculum on ophthalmic resident cataract surgery rates. J Cataract Refract Surg. 2009;35:1956–1960. doi: 10.1016/j.jcrs.2009.05.046. [DOI] [PubMed] [Google Scholar]
- 9.Schulze-Bonsel K, Feltgen N, Burau H, Hansen L, Bach M. Visual acuities “hand motion” and “counting fingers” can be quantified with the Freiburg visual acuity test. Invest Ophthalmol Vis Sci. 2006;47:1236–1240. doi: 10.1167/iovs.05-0981. [DOI] [PubMed] [Google Scholar]
- 10.Berler DK. Intraoperative complications during cataract surgery in the very old. Trans Am Ophthalmol Soc. 2000;98:127–132. [PMC free article] [PubMed] [Google Scholar]
- 11.Kim JY, Ali R, Cremers SL, Yun SC, Henderson BA. Incidence of intraoperative complications in cataract surgery performed by left-handed residents. J Cataract Refract Surg. 2009;35:1019–1025. doi: 10.1016/j.jcrs.2009.01.025. [DOI] [PubMed] [Google Scholar]
- 12.Narendran N, Jaycock P, Johnston RL, Taylor H, Adams M, Tole DM, Asaria RH, Galloway P, Sparrow JM. The Cataract National Dataset electronic multicentre audit of 55 567 operations: risk stratification for posterior capsule rupture and vitreous loss. Eye. 2009;23:31–37. doi: 10.1038/sj.eye.6703049. [DOI] [PubMed] [Google Scholar]
- 13.Rutar T, Porco TC, Naseri A. Risk factors for intraoperative complications in resident-performed phacoemulsification surgery. Ophthalmology. 2009;116:431–436. doi: 10.1016/j.ophtha.2008.10.028. [DOI] [PubMed] [Google Scholar]
- 14.Osborne SA, Adams WE, Bunce CV, Fraser SG. Validation of two scoring systems for the prediction of posterior capsule rupture during phacoemulsification surgery. Br J Ophthalmol. 2006;90:333–336. doi: 10.1136/bjo.2005.080754. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Artzén D, Lundström M, Behndig A, Stenevi U, Lydahl E, Montan P. Capsule complication during cataract surgery: case-control study of preoperative and intraoperative risk factors. Swedish Capsule Rupture Study Group report 2. J Cataract Refract Surg. 2009;35:1688–1693. doi: 10.1016/j.jcrs.2009.05.026. [DOI] [PubMed] [Google Scholar]
- 16.Nagashima RJ. Decreased incidence of capsule complications and vitreous loss during phacoemulsification in eyes with pseudoexfoliation syndrome. J Cataract Refract Surg. 2004;30:127–131. doi: 10.1016/S0886-3350(03)00465-6. [DOI] [PubMed] [Google Scholar]
- 17.Hyams M, Mathalone N, Hershovitz M, Hod Y, Israeli D, Geyer O. Intraoperative complications of phacoemulsification in eyes with and without pseudoexfoliation. J Cataract Refract Surg. 2005;31:1002–1005. doi: 10.1016/j.jcrs.2004.09.051. [DOI] [PubMed] [Google Scholar]
- 18.Shingleton BJ, Heltzer J, O’Donoghue MW. Outcomes of phacoemulsification in patients with and without pseudoexfoliation syndrome. J Cataract Refract Surg. 2003;29:1080–1086. doi: 10.1016/s0886-3350(02)01993-4. [DOI] [PubMed] [Google Scholar]
- 19.Shingleton BJ, Crandall AS, Ahmed IIK. Pseudoexfoliation and the cataract surgeon: preoperative, intraoperative, and postoperative issues related to intraocular pressure, cataract, and intraocular lenses. J Cataract Refract Surg. 2009;35:1101–1120. doi: 10.1016/j.jcrs.2009.03.011. [DOI] [PubMed] [Google Scholar]
- 20.Pinter SM, Sugar A. Phacoemulsification in eyes with past pars plana vitrectomy: case-control study. J Cataract Refract Surg. 1999;25:556–561. doi: 10.1016/s0886-3350(99)80055-8. [DOI] [PubMed] [Google Scholar]
- 21.Brazitikos PD, Tsinopoulos IT, Papdopoulos NT, Fotiadis K, Stangos NT. Ultrasonographic classification and phacoemulsification of white senile cataracts. Ophthalmology. 1999;106:2178–2183. doi: 10.1016/S0161-6420(99)90502-X. [DOI] [PubMed] [Google Scholar]
- 22.Osher RH, Yu BC, Koch DD. Posterior polar cataracts: a predisposition to intraoperative posterior capsular rupture. J Cataract Refract Surg. 1990;16:157–162. doi: 10.1016/s0886-3350(13)80724-9. [DOI] [PubMed] [Google Scholar]
- 23.Vasavada A, Singh R. Phacoemulsification in eyes with posterior polar cataract. J Cataract Refract Surg. 1999;25:238–245. doi: 10.1016/s0886-3350(99)80133-3. [DOI] [PubMed] [Google Scholar]
- 24.Muhtaseb M, Kalhoro A, Ionides A. A system for preoperative stratification of cataract patients according to risk of intraoperative complications: a prospective analysis of 1441 cases. Br J Ophthalmol. 2004;88:1242 –1246. doi: 10.1136/bjo.2004.046003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Habib MS, Bunce CV, Fraser SG. The role of case mix in the relation of volume and outcome in phacoemulsification. Br J Ophthalmol. 2005;89:1143–1146. doi: 10.1136/bjo.2005.070235. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Najjar DM, Awwad ST. Cataract surgery risk score for residents and beginning surgeons. J Cataract Refract Surg. 2003;29:2035–2036. doi: 10.1016/j.jcrs.2003.08.004. [DOI] [PubMed] [Google Scholar]
- 27.Blomquist PH, Sargent JW, Winslow HH. Validation of Najjar-Awwad cataract surgery risk score for resident phacoemulsification surgery. J Cataract Refract Surg. 2010;36:1753–1757. doi: 10.1016/j.jcrs.2010.04.035. [DOI] [PMC free article] [PubMed] [Google Scholar]