Paul G. Ursell

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.

Cystoid macular edema after phacoemulsification: Relationship to blood-aqueous barrier damage and visual acuity

PURPOSE To ascertain the incidence of cystoid macular edema (CME) after phacoemulsification and its relationship to blood-aqueous barrier damage and visual acuity. SETTING A British teaching hospital. METHODS A prospective trial was performed to document the incidence of CME after routine phacoemulsification with continuous curvilinear capsulorhexis. LogMAR visual acuity and laser flare were measured using the KOWA FC 1000 laser cell-flare meter preoperatively and 1, 14, 30, and 60 days postoperatively. At day 60, a standardized fluorescein angiogram was performed and graded by masked observers. RESULTS The rate of angiographic CME on day 60 was 19%. Visual acuity at each visit was significantly worse in the CME group (P < .05). The flare and cell values at days 14, 30, and 60 were higher in the CME group at day 60; however, the difference was not statistically significance (P > .05). CONCLUSIONS The incidence of CME after routine phacoemulsification was 19%. Patients with CME at day 60 had significantly worse visual acuity than those who did not from the first postoperative day throughout the follow-up. There was a trend for patients who had CME at day 60 to have more postoperative inflammation.

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.

Anterior capsule stability in eyes with intraocular lenses made of poly(methyl methacrylate), silicone, and AcrySof

Purpose: To ascertain whether the movement of the anterior capsule is different with intraocular lenses (IOLs) made from different materials. Setting: Department of Ophthalmology, St. Thomas’ Hospital, London, United Kingdom. Methods: Ninety patients had standardized extracapsular cataract extraction, continuous curvilinear capsulorhexis (CCC), and confirmed in‐the‐bag IOL placement performed by the same surgeon. Patients were randomized to receive a threepiece, 6.0 mm IOL made of poly(methyl methacrylate) (PMMA), silicone, or AcrySof®, all with PMMA haptics, and received standardized postoperative medication. Except for material, the IOLs were of the same design. On days 7, 30, 90, 180, and 360, digitized retroillumination images were taken of the IOL. The movement of the anterior capsule between each visit was analyzed. Results: The amount of anterior capsule movement was significantly less in the AcrySof lens group than in the PMMA or silicone lens groups in the first year after surgery (P = .0001). Conclusion: The AcrySof lens with PMMA haptics produced significantly less anterior capsule movement than PMMA or silicone lenses and thus is likely to cause less IOL decentration and capsular phimosis.

High-resolution digital retroillumination imaging of the posterior lens capsule after cataract surgery

Purpose: To develop a system for high‐resolution imaging of the posterior lens capsule after intraocular lens surgery for objective assessment of posterior capsule opacification (PCO). Setting: Department of Cataract and Refractive Surgery, St. Thomas’ Hospital, London, United Kingdom. Methods: A system was developed that uses coaxial illumination and imaging based on Zeiss components with a digital camera directly linked to a computer for online image verification and image analysis. Results: The system produced high‐resolution digital images with even background illumination of sufficient quality to demonstrate progressive lens epithelial cell changes that are amenable to computer image analysis. Conclusion: This system produced excellent images for objective documentation and quantitative measurement 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.

The Effect of Solution Temperature on the Pain of Penbulbar Anesthesia

BACKGROUND Peribulbar anesthesia is the preferred technique of local anesthesia of the majority of cataract surgeons. Local anesthetic injections at other sites in the body have been shown to be less painful if the solution is warmed to body temperature before injection. To determine whether this is of advantage with peribulbar anesthesia, the authors performed a prospective, randomized, single, blind trial comparing local anesthetic injections that have been warmed to room temperature. METHODS Forty consecutive patients undergoing routine cataract surgery were randomized into two groups of 20 patients and received local anesthetic at 20 degrees C or 37 degrees C. The peribulbar injection contained a solution of 5 ml 2% Lignocaine, 5 ml 0.5% bupivicaine (Marcaine), and 1550 IU hyaluronidase (HYlase) in a 10-ml syringe on a 25-mm, 25-gauge needle. Seven milliliters of the final solution was injected transcutaneously at the junction of the lateral and medial thirds of the lower lid. The patients graded the pain of the injection using a visual analogue scale. RESULTS The pain sensation of local anesthesia is less when the solution is warmed to body temperature compared with room temperature (P = 0.026, using an unpaired Students t test). CONCLUSION Warming the local anesthetic used in peribulbar anesthesia to body temperature before injection reduces this iatrogenic pain significantly.

Neovascular glaucoma as a complication of retinal vasculitis in Crohn disease

PURPOSE To report a case of neovascular glaucoma as a complication of retinal vasculitis in Crohn disease. METHODS Case report with fluorescein angiogram. RESULTS A 62-year-old man with biopsy-proven Crohn disease presented with bilateral uveitis, bilateral iris new vessels, and neovascular glaucoma in the left eye. Fluorescein angiography revealed signs of retinal vasculitis and capillary nonperfusion in both eyes. CONCLUSION Crohn disease may be associated with retinal vasculitis and, thus, neovascular glaucoma. A satisfactory result can be achieved by using corticosteroids to control the retinal vascular inflammation, by applying panretinal photocoagulation and by controlling the increased intraocular pressure surgically.