Emma J. Hollick

Relationship between intraocular lens biomaterials and posterior capsule opacification

Purpose: To determine whether posterior capsule opacification (PCO) is influenced by intraocular lens (IOL) material. Setting: A British teaching hospital eye department. Methods: Ninety eyes were prospectively randomized to receive a poly(methyl methacrylate) (PMMA), silicone, or AcrySof® IOL. All lenses had 6,0 mm optics and PMMA haptics. A standardized surgical protocol was performed by a single surgeon using an extracapsular technique with capsulorhexis. Patients having surgical complications were excluded, and all patients had standardized medication and follow‐up. Posterior capsule opacification was assessed by a digital retroillumination camera using a dedicated software program based on the analysis of texture in the image and calculated as the percentage area of opacified capsule. Data were analyzed 2 years postoperatively. Results: There was a significant difference in percentage of PCO at 2 years among the three lens types (P < .0001). The AcrySof lenses were associated with less PCO (median 11.75%) than PMMA (43.65%) and silicone (33.50%) lenses (P < .001 and P = .025, respectively). The difference between PMMA and silicone lenses was not statistically significant. Conclusion: Intraocular lenses made from AcrySof were associated with a significantly reduced degree of PCO.

The effect of polymethylmethacrylate, silicone, and polyacrylic intraocular lenses on posterior capsular opacification 3 years after cataract surgery

OBJECTIVE To compare the visual outcome, neodymium:YAG (Nd:YAG) capsulotomy rates, and percentage of posterior capsular opacification (PCO) seen with polymethylmethacrylate (PMMA), silicone, and polyacrylic intraocular lens implants 3 years after surgery. DESIGN Randomized, prospective trial. PARTICIPANTS Ninety eyes of 81 patients were examined at a British teaching hospital. INTERVENTION Ninety eyes were prospectively randomized to receive a PMMA, silicone, or polyacrylic (AcrySof, Alcon, Fort Worth, TX) implant. All lenses had 6-mm disc optics with PMMA haptics. A standardized surgical protocol was performed by a single surgeon using an extracapsular technique with capsulorhexis; any surgical complications were excluded and all patients had standardized postoperative medication and follow-up. MAIN OUTCOME MEASURES Patients were seen at 6 months and 1, 2, and 3 years after surgery. At 3 years, logarithm of the minimum angle of resolution (LogMAR) visual acuity and Pelli-Robson contrast sensitivity were measured and YAG capsulotomy rates determined. Posterior capsular opacification was assessed objectively by digital retroillumination imaging using dedicated software and calculated as the percentage area of opacified capsule. RESULTS At 3 years, the overall follow-up rate was 71%: 19 patients were available for examination with polyacrylic lens implants, 22 with silicone, and 23 with PMMA. There was a significant difference in percentage PCO at 3 years among the lens types (P = 0.0001). Polyacrylic lenses were associated with less PCO (10%) than silicone (40%) and PMMA lenses (56%). The YAG capsulotomy rate was 0% for polyacrylic, 14% for silicone, and 26% for PMMA (P = 0.05). The visual acuity and contrast sensitivity were not significantly different among the three groups if patients with age-related macular degeneration and those requiring YAG capsulotomies are excluded. CONCLUSIONS Intraocular lenses made from polyacrylic are associated with a significantly reduced degree of PCO and lower YAG rates.

The effect of capsulorhexis size on posterior capsular opacification: one-year results of a randomized prospective trial

PURPOSE Posterior capsular opacification is the most common surgically related cause of reduced vision after cataract surgery. We studied the effect of capsulorhexis size on the pattern and severity of posterior capsular opacification. METHODS In this prospective study 75 patients underwent standardized phacoemulsification with capsulorhexis and in-the-bag placement of a 5.5-mm polymethylmethacrylate intraocular lens implant. The patients were randomly assigned to receive either a small capsulorhexis of 4.5 to 5 mm to lie completely on the intraocular lens optic or a large capsulorhexis of 6 to 7 mm to lie completely off the lens optic. Patients were examined at days 1, 14, 30, 90, and 180 and at year 1 with logMAR visual acuity assessment, Pelli-Robson contrast sensitivity testing, anterior chamber flare and cell measurement, and high-resolution digital retroillumination imaging of the posterior capsule. The pattern of posterior capsular opacification was determined, and the percentage area of posterior capsular opacification was calculated for each image with dedicated image analysis software. RESULTS Large capsulorhexes were associated with significantly more wrinkling of the posterior capsule and worse posterior capsular opacification than small capsulorhexes. At 1 year the average percentage area of posterior capsular opacification was 32.7% for small capsulorhexes (95% confidence interval, 19.8 to 45.6) and 66.2% for large capsulorhexes (95% confidence interval, 57.7 to 74.6) (P = .0001). The patients with large capsulorhexes had significantly poorer visual acuities and a trend toward worse contrast sensitivities. CONCLUSION This study demonstrated significantly greater wrinkling and opacification of the posterior capsule and worse visual acuity with large capsulorhexes than with small capsulorhexes. In cataract surgery with a polymethylmethacrylate intraocular lens, a small capsulorhexis with the edge completely on the surface of the implant is preferable to a large capsulorhexis in reducing posterior capsular opacification.

Biocompatibility of poly(methyl methacrylate), silicone, and AcrySof intraocular lenses: Randomized comparison of the cellular reaction on the anterior lens surface

Purpose: To determine the foreign‐body response to three intraocular lens (IOL) biomaterials (poly[methyl methacrylate] {PMMA], silicone, and AcrySof) and use this as an indicator of their comparative biocompatibility postoperatively within the eye. Setting: A British teaching hospital eye department. Methods: Ninety eyes were prospectively randomized to receive a PMMA, silicone, or AcrySof IOL. All lenses had 6.0 mm optics with PMMA haptics. A standardized surgical protocol was performed by a single surgeon using an extracapsular technique with`capsulorhexis; eyes that experienced a surgical complication were excluded. All patients had standardized postoperative medication and follow‐up. Specular microscopy of the anterior IOL surface was carried out after pupil dilation on days 1, 7, 30, 90, 180, 360, and 720 to assess small cell and giant cell reactions. Results: All three IOL types produced a mild degree’ of nonspecific foreign‐body response, which resolved over the study period without detrimental effect. The silicone group had significantly higher small cell counts than the PMMA and AcrySof groups (P = .02); the AcrySof group had significantly lower giant cell counts than the other two groups (P = .003). Conclusion: The three IOL types were sufficiently biocompatibfe to function in normal eyes with age‐related cataracts. However, AcrySof IOLs were associated with lower giant cell counts than PMMA and silicone IOLs and might produce better results in eyes with pre‐existing blood‐aqueous barrier damage.

Lens epithelial cell regression on the posterior capsule with different intraocular lens materials

BACKGROUND/AIMS Posterior capsular opacification (PCO) is caused by proliferation and migration of lens epithelial cells (LECs) across the posterior capsule and is the commonest cause of reduced vision after cataract surgery. The influence of intraocular lens (IOL) material on the process of LEC migration was studied. METHODS 90 eyes underwent standardised extracapsular surgery, with capsulorhexis and “in the bag” IOL placement. They were randomised to receive a three piece 6 mm lens of PMMA, silicone, or polyacrylic (AcrySof, Alcon, Fort Worth, TX, USA). On days 7, 30, 90, 180, and years 1 and 2 high resolution digitised retroillumination images were taken of the posterior capsule. The presence of LECs was determined at 90 days and 2 years, and their progression or regression was established by serial examination of images. RESULTS LECs were seen in 93% of silicone and 97% of PMMA IOLs at 90 days, compared with 46% of polyacrylic (p<0.001). At year 2 LECs were present in all patients with silicone or PMMA lenses, whereas 62% of patients with polyacrylic IOLs had LECs (p<0.001). Of those patients with LECs at day 90 LEC regression occurred in 8% with silicone IOLs and 15% of PMMA cases, compared with 83% of patients with polyacrylic IOLs (p<0.0001). CONCLUSION The presence of LECs on the posterior capsule was considerably lower with polyacrylic than PMMA or silicone IOLs and LEC regression occurred more frequently. The lower incidence of LECs and the higher rate of regression may explain why PCO formation appears to be reduced with polyacrylic lenses. This has important clinical implications for the prevention of PCO.

Posterior capsular opacification with hydrogel, polymethylmethacrylate, and silicone intraocular lenses: two-year results of a randomized prospective trial.

PURPOSE To compare the visual outcome, percentage of posterior capsular opacification, and laser capsulotomy rates with polymethylmethacrylate, silicone, and hydrogel intraocular lens implants at 1 and 2 years postoperatively. METHODS Ninety-three eyes of 93 patients were randomized to receive a polymethylmethacrylate, silicone, or hydrogel intraocular lens implant. A standardized surgical protocol was followed by a single surgeon using phacoemulsification with capsulorhexis; any patients with surgical complications were excluded, and all patients received standardized medication and follow-up. Patients were examined at days 1 and 7, months 1, 3, and 6, and years 1 and 2 after surgery. At each assessment, best-corrected logMAR visual acuity and Pelli-Robson contrast sensitivity were measured. Posterior capsular opacification was objectively assessed by digital retroillumination imaging with the use of a dedicated software program and calculated as the percentage area of opacified capsule. Laser capsulotomy was performed if the eye had lost 2 lines of visual acuity with a clinically opaque capsule. RESULTS At 2 years postoperatively, the mean percentage area of posterior capsular opacification for hydrogel lenses was 63%; for polymethylmethacrylate, 46%; and for silicone, 17%. Hydrogel intraocular lenses were associated with 17% more posterior capsule opacification than were polymethylmethacrylate lenses (95% confidence interval, 1-33; P =. 037) and 45% more than were silicone lenses (95% confidence interval, 33-58; P <.0001) at 2 years. Polymethylmethacrylate lenses had 28% more posterior capsule opacification than silicone lenses (95% confidence interval, 13-43; P <.0001) at 2 years. Twenty-eight percent of patients with hydrogel intraocular lenses required an Nd:YAG laser posterior capsulotomy at 2 years, compared with 14% with polymethylmethacrylate, whereas no patients with silicone lenses needed a capsulotomy (P =.014). Visual acuity was not significantly different among the three groups, but patients with silicone intraocular lenses had significantly better contrast sensitivity than those with hydrogel lenses (P =.046). CONCLUSIONS Intraocular lenses made of this specific hydrogel were associated with a significantly higher degree of posterior capsular opacification and more laser capsulotomies than polymethylmethacrylate and silicone intraocular lenses.

Double-masked prospective ocular safety study of a lens epithelial cell antibody to prevent posterior capsule opacification

PURPOSE To evaluate the intraocular safety of an immunoconjugate (MDX-RA) developed to prevent posterior capsule opacification (PCO) in human eyes. SETTING St. Thomass Hospital Eye Department, London, United Kingdom. METHODS Twenty-six patients had phacoemulsification and implantation of an intraocular lens (IOL). All were randomly allocated at the end of surgery to receive a 0.1 mL placebo or 0.1 mL of the immunotoxin MDX-RA intracamerally. Two doses of the drug were tested: 8 patients with a low dose (50 units), 9 patients with a high dose (100 units), and 9 with placebo. Follow-up at days 1, 14, 30, 60, 90, and 180 consisted of visual acuity measured by the Early Treatment of Diabetic Retinopathy Study test, contrast sensitivity, aqueous flare, specular microscopy of the IOLs anterior surface, and corneal endothelial counts. The percentage area of PCO was measured from retroillumination images of the posterior capsule. RESULTS There was no decrease in corneal endothelial cell count in toxin-treated patients. Early postoperative flare, anterior chamber cell count, and corneal pachymetry were higher in toxin-treated patients. The median percentage area of PCO at 1 year was 32.0 in the placebo group, 3.8 in the low-dose group, and 7.4 in the high-dose group (P = .06). CONCLUSION This prospective, randomized, placebo-controlled trial confirmed that MDX-RA is safe for intraocular use and is of potential value for further clinical trials of the prevention of PCO.

The Effect of Polymethylmethacrylate and AcrySof Intraocular Lenses on the Posterior Capsule in Patients with a Large Capsulorrhexis

PURPOSE We have previously shown that patients who have a capsulorrhexis larger than the diameter of a polymethylmethacrylate (PMMA) intraocular lens (IOL) rapidly develop increased posterior capsule opacification (PCO), in effect, producing an example of enhanced PCO. This study focuses on the influence of AcrySof IOLs on this process. METHODS Phacoemulsification was performed on two groups of patients. The first consisted of 38 patients with a large capsulorrhexis of 6-7 mm who received a 5.5-mm PMMA IOL. The second group of 32 patients had identical surgery and a 5.5-mm MA30 AcrySof IOL was implanted. On days 1,14, 28, 90, 180, and 360, high resolution digitized retroillumination images were taken of the posterior capsule. The PCO area was measured by image analysis at 90, 180, and 360 days. Wrinkling of the posterior capsule was determined at 90 days, and the progression or regression of lens epithelial cell (LEC) proliferation was established by examination of serial images at 28 and 180 days. RESULTS At 90 days, 79% of the patients with PMMA IOLs had moderate to severe wrinkling of the posterior capsule, whereas the patients with AcrySof IOLs had none (P <.001). The percentage of PCO area was 69% for the PMMA IOLs and 24% for the AcrySof IOL group at 360 days (P <.0001). In the PMMA group, LEC progression occurred in 77%, LEC growth was stable in 15%, and LEC regression occurred in only 8%, compared to 69% of patients with AcrySof IOLs (P <.0001). CONCLUSIONS In patients with a rhexis larger than the IOL, AcrySof IOLs potentially can prevent capsular wrinkling and cause less PCO than a PMMA IOL with a similar rhexis size. The LEC regression occurs with AcrySof between 28 and 180 days. The reasons for this are discussed.

Modeling Endothelial Cell Loss After Descemet Stripping Endothelial Keratoplasty: Data From 5 Years of Follow-up

Purpose: To report 5-year outcomes for graft survival and endothelial cell survival after Descemet stripping endothelial keratoplasty (DSEK) including regression modeling for cell survival over time. Methods: This is a single-institution, retrospective, consecutive interventional series of 210 primary DSEK grafts operated for low-to-moderate risk indications, specifically Fuchs dystrophy and bullous keratopathy. Primary outcomes were cumulative graft survival and % endothelial cell loss from 3 months through 5 years; the secondary outcome was to trend endothelial cell density over time by least-squares and mixed nonlinear modeling. Results: Cumulative graft survival was high at 99%, 98%, and 94% at 1, 3, and 5 years, respectively. Mean endothelial cell loss was (mean ± SD) 44% ± 16%, 56% ± 17%, and 67% ± 13% at 1, 3, and 5 years. The trend in mean endothelial cell density over time by least square regression was accurately and parsimoniously described by a straight line taking earliest values (3 mo) through to 5 years, with a rate of cell loss of 148 ± 13 cells·mm−2·yr−1. Higher-order polynomial and exponential models did not provide a closer regression fit. Mixed nonlinear modeling using exponential decay equations confirmed a relatively stable rate of cell loss for DSEK from 3 months through to 5 years, in contrast to penetrating keratoplasty models using similar techniques in previous studies. Conclusions: DSEK graft survival is high in our series through 5 years. Endothelial cell loss occurs at a relatively constant albeit low-grade rate from the earliest postoperative measurements through 5 years.

Center and Surgeon Effect on Outcomes of Endothelial Keratoplasty Versus Penetrating Keratoplasty in the United Kingdom

WE APPRECIATE THE INTEREST BY CHEN AND ASSOCIates in our recent study of predictive risk factors for endogenous endophthalmitis among hospitalized patients with hematogenous infections. They raise several important points that should certainly be considered in evaluating patients, and that merit discussion. In itemized response: First, as Dr Chen and colleagues note, patients with more severe disease frequently require longer hospitalizations and longer treatment with intravenous antimicrobials. Since treatment with intravenous antimicrobials may sometimes be continued in an outpatient setting (home health care or visits to an infusion center), we considered longer hospitalizations to be an indicator of more severe infection or worse systemic health. Compared to fungemia, bacteremia (including sepsis) was associated with markedly lower rates of presumed endogenous endophthalmitis. Among patients with bacterial infections, 0.04% of patients with bacteremia and 0.09% of patients with septicemia (defined as ICD-9 codes 995.91 and 995.92) developed endophthalmitis. However, among patients with bacteremia, sepsis was associated with a nonsignificant odds ratio of 0.71 for development of endogenous endophthalmitis (CI 0.48–1.05, P 1⁄4 .09). We suspect this may reflect low numbers, as well as overlap and unreliability/inconsistency in coding of sepsis vs bacteremia. Second, regarding urinary tract infection, we are not aware of routine positive urine cultures among patients with bacteremia or fungemia; however, for all of the reasons stated, we agree that patients with urinary tract infection should be considered individually. Third, owing to the limitations inherent in code-based data, we lack sufficient granularity to evaluate patients with renal disease from diabetes vs other cause. Although there is an ICD-9 diagnosis code for diabetes with renal manifestations, it is separate from the code for chronic renal failure/chronic kidney disease (for which etiology is unspecified), and we cannot reliably elaborate on clinical details for the 17 patients with chronic renal disease and endogenous endophthalmitis. We included only first-hospitalization data to avoid over-representing patient factors. Since odds were calculated for patient hospitalizations, the sample would have