Comparison of the postoperative inflammatory response in the normal eye with heparin-surface-modified and poly(methyl methacrylate) intraocular lenses

Factors influencing aqueous flare after cataract surgery and its evaluation with laser flare photometry

Despite the refinement of modern cataract surgery, postoperative inflammation still constitutes a substantial amount of visual morbidity worldwide. A surrogate for intraocular inflammation and blood-aqueous barrier breakdown can be objectively quantified by Laser flare photometry (LFP). This review outlines the utility of LFP in assessing the assessment of post-cataract surgery inflammation. It highlights the impact of preoperative pathological states such as uveitis and diabetes, intraoperative techniques, including efficient phacoemulsification and direct comparisons between postoperative anti-inflammatory regimes. There is a large interobserver variation in the subjective flare measurement after cataract surgery and the continued use of LFP amongst other objective, noninvasive measurements of intraocular inflammation, particularly in the further development of cataract surgery, is recommended.

Physicochemical and surface properties of acrylic intraocular lenses and their clinical significance

To analyze and compare several commercially available acrylic intraocular lenses (IOLs) with particular regard to their clinical significance, we examined the physicochemical and surface properties of four currently available acrylic IOLs using static water contact angle, atomic force microscopy (AFM), Raman spectroscopy, and differential scanning calorimetry (DSC) measurements. The hydrophobic acrylic IOLs, ZA9003, and MA60BM, had contact angles ranging from 77.9° ± 0.65° to 84.4° ± 0.09°. The contact angles in the hydrophilic acrylic (970C) and heparin-surface-modified (HSM) hydrophilic acrylic IOLs (BioVue) were 61.8° ± 0.45° and 69.7° ± 0.76°, respectively. The roughness of the IOL optic surface differed depending on the type of IOL (p < 0.001). The surface roughness of BioVue had the lowest value: 5.87 ± 1.26 nm. This suggests that the BioVue IOL may lead to reduced cellular adhesion compared to the unmodified IOLs. All IOLs including those composed of acrylic optic materials from different manufacturers showed distinct Raman spectra peaks. The glass transition temperatures (T_g) for the hydrophobic acrylic IOLs were between 12.5 and 13.8 °C. These results suggest that the intraoperative and postoperative behavior of an IOL can be predicted. This information is also expected to contribute greatly to the industrial production of reliable biocompatible IOLs.

Laser flare-cell photometer: principle and significance in clinical and basic ophthalmology

A slit-lamp examination is an indispensable and essential clinical evaluation method in ophthalmology, but, it is qualitative subjective. To complement its weaknesses in making a quantitative evaluation of flare intensity and number of cells in the aqueous humor in the eye, we invented the laser flare-cell photometer in 1988. The instrument enables a non-invasive quantitative evaluation of flare intensity and number of cells in the aqueous with good accuracy and repeatability as well as maneuverability equal to slit-lamp microscopy. The instrument can elucidate the pathophysiology in the blood-aqueous barrier (BAB) function in a variety of ocular disorders. The accuracy of the instrument makes it possible to investigate not only the pathophysiology of intraocular disorders but also the effects of various drugs and surgical procedures in BAB. The instrument does not only lighten the burden on patients in clinical examinations and study but it also helps minimize the sacrifice of experimental animals and improves the reliability of the results by minimizing inter-individual variations through its good repeatability. Here I shall relate how the instrument has been applied to clinical and basic studies in ophthalmology and what novel knowledge its application contributed to pathophysiology in ophthalmology.

Surface modification of intraocular lenses with hyaluronic acid and lysozyme for the prevention of endophthalmitis and posterior capsule opacification

Posterior capsule opacification is one of the complications of cataract surgery caused by the adhesion and reproduction of residual human lens epithelial cells (HLECs) on the posterior capsule.

Analysis of intraocular lens surface properties with atomic force microscopy

PURPOSE

To analyze the surface optics of 4 currently available intraocular lenses (IOLs) with atomic force microscopy.

SETTING

Licryl Laboratory, University of Calabria, Rende, Italy.

METHODS

The surface roughness and topography of poly(methyl methacrylate) (PMMA), silicone, hydrophobic, and hydrophilic acrylic IOLs were evaluated with atomic force microscopy in contact mode. The analysis was performed in a liquid environment using cantilevers with a 0.01 Newtonw/meter nominal elastic constant. Measurements were made over areas of 10 microm2 on different locations of the posterior optic surface of the IOL.

RESULTS

Atomic force microscopy permitted high-resolution imaging of IOL optic surface characteristics. Surface topography showed different features with respect to the lens biomaterial. The root-mean-square roughness of the IOL optic surface was significantly different between lenses of various materials (P < .001). The hydrophobic acrylic and silicone IOLs had the lowest mean surface roughness, 3.8 nm +/- 0.2 (SD) and 4.0 +/- 0.5 nm, respectively, and the 2 PMMA IOLs had the highest mean surface roughness, 6.6 +/- 0.3 nm and 7.0 +/- 0.6 nm.

CONCLUSIONS

Atomic force microscopy was effective and accurate in analyzing IOL optics. The surface topography of IOLs may vary with different manufacturing processes.

Quantification of blood-aqueous barrier breakdown after phacoemulsification in Fuchs' heterochromic uveitis

PURPOSE

To quantify the breakdown of the blood-aqueous barrier (BAB) following phacoemulsification with posterior chamber lens implantation in eyes with Fuchs' heterochromic uveitis (FHU).

PATIENTS AND METHODS

In this retrospective study, 19 eyes of 19 patients with FHU (mean age 38 +/- 14 years) and 35 eyes of 35 patients with senile cataracts (mean age 63 +/- 9 years) underwent phacoemulsification with one-piece PMMA posterior chamber lens implantation. Aqueous flare was quantified using the laser flare-cell meter (LFCM, Kowa FC-1000) following medical pupillary dilation preoperatively and 1, 3, and 5 days, then 1 and 6 weeks and 6 months postoperatively.

RESULTS

Mean preoperative aqueous flare (in photon counts per millisecond) in FHU vs. controls was 11.7 +/- 3.5 vs. 5.8 +/- 1.7. Following cataract surgery, mean aqueous flare increased to 27.8 +/- 4.4 vs. 16.0 +/- 4.5 on day 1, decreased to 23.6 +/- 4.0 vs. 11.8 +/- 3.5 on day 3, and to 18.0 +/- 3.0 vs. 9.5 +/- 1.7 on day 5. In FHU eyes, it was 13.9 +/- 2.7 after 1 week, and had returned to preoperative levels after 6 weeks (10.9 +/- 2.5) and remained stable for up to 6 months (mean 10.3 +/- 2.2). Pre- and postoperatively, aqueous flare values were 2-3 times higher in FHU eyes than in control eyes with senile cataract (p = 0.01). No postoperative complications such as fibrin formation, synechiae, macrophages on the intraocular lens optic or endophthalmitis were observed in any of the patients.

CONCLUSIONS

BAB breakdown following phacoemulsification with posterior chamber lens implantation is relatively mild in eyes with FHU and the BAB appears to be fully reestablished to preoperative levels 6 weeks postoperatively, explaining the usually good outcome of cataract surgery in this condition.

Hydrophobic acrylic versus heparin surface-modified polymethylmethacrylate intraocular lens: a biocompatibility study

BACKGROUND

The implant of intraocular lenses (IOLs) following cataract surgery induces a foreign-body reaction to the IOL and a response on the part of the lens epithelial cells (LECs). The purpose of this study was to compare these aspects after the implantation of two different IOL materials.

METHODS

Thirty-six cataract patients were randomised to receive two different foldable lens: an acrylic hydrophobic IOL (Acrysof MA30BA) and a heparin surface-modified (HSM) polymethylmethacrylate IOL (Pharmacia & Upjohn 809C) after phacoemulsification. Slit-lamp biomicroscopy with specular technique was used to assess the inflammatory cell adhesion on the anterior IOL surface, anterior capsule opacification (ACO) and membrane growth from the rhexis edge at 7, 30, 90, 180 and 360 days after surgery.

RESULTS

The 809C group showed a higher percentage of patients with slight inflammatory cell adhesion on the anterior cell surface and a higher small cellular density during the whole follow-up period. The epithelioid cell response was greater in the 809C group than the Acrysof group but the difference between the two groups was not statistically significant. The ACO increased during the follow-up in both groups but was significantly higher in the 809C group.

CONCLUSION

Acrysof lenses are more biocompatible than HSM IOLs, showing a lower grade of inflammatory cell adhesion and ACO. The implantation of these lenses may be particularly indicated in patients with pathologies predisposing to blood-aqueous barrier damage.

Effect of aminoglycosides (sub-MICs) on adherence of coagulase-negative Staphylococci to intraocular lens surface

The authors evaluated the in vitro effects of subinhibitory concentrations (sub-MICs) of aminoglycosides (gentamicin, netilmicin and tobramycin) on the adherence of coagulase-negative staphylococcus to intraocular lens (PMMA, acrylic and heparin) surface. The five strains of coagulase-negative Staphylococcus epidermidis used (S. epidermidis IMe7, IMe11, IMe27, IMe29 and IMe31) were tested for their ability to produce slime. The minimum inhibitory concentrations (MIC) indicated high susceptibility in vitro to the antibiotics and homogeneous values. The adhesion tests without antibiotics (K1, K2 and K3) for every time considered (30 min, 60 min and 180 min) and for all examined strains showed more constant adhesive activity on the surface of acrylic intraocular lens (IOLs) than on the surface of heparin IOLs. The aminoglycosides tested were able to reduce adhesivity by coagulase-negative S. epidermidis slime to the IOL surfaces, even at sub-MICs. The documentation obtained by scanning electron microscope shows the growth of a strain of S. epidermidis IMe11 after 180 minutes of contact which remains adherent to the surface of the acrylic IOLs.

Short-term blood-aqueous barrier breakdown after implantation of the 1CU accommodative posterior chamber intraocular lens

PURPOSE

To quantify intraocular inflammation after phacoemulsification with implantation of an accommodative posterior chamber intraocular lens (IOL).

SETTING

Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany.

METHODS

Twenty cataractous eyes of 20 patients without preexisting blood-aqueous barrier (BAB) deficiencies or previous intraocular surgery were included in this study. The mean age of the patients was 64.6 years +/- 16.0 (SD). A single surgeon performed phacoemulsification through a superior sclerocorneal tunnel incision and implantation of a 1CU IOL (HumanOptics AG) though a 3.2 mm incision. The haptics of the single-piece acrylic 1CU lens are designed for anterior optic movement following ciliary muscle contraction. The postoperative treatment was standardized. Postoperative BAB breakdown was quantified by laser flare photometry (FC-1000, Kowa) at 1 day, 1 and 4 weeks, and 3 and 6 months.

RESULTS

The mean aqueous flare was 6.3 photons/ms +/- 3.0 (SD) (range 4.0 to 12.2 photons/ms) 1 day postoperatively, with 64% of patients having normal aqueous flare values (<8.0 photons/ms). One week after surgery, the mean aqueous flare was 5.3 +/- 2.8 photons/ms (range 2.0 to 10.5 photons/ms). Four weeks postoperatively, aqueous flare was normal in all patients and remained stable below the normal limit for up to 6 months (mean 3.3 +/- 1.2 months; range 2.0 to 5.4 months). The number of aqueous cells did not increase at any follow-up and was normal in all eyes. No postoperative complications such as fibrin formation, synechias, macrophages on the IOL optic, or endophthalmitis were observed.

CONCLUSIONS

Phacoemulsification with implantation of the 1CU accommodative IOL led to minimal and short-lasting BAB alteration. No signs of persistent inflammation or pigment dispersion were detected.

Biocompatibility of hydrophilic intraocular lenses

PURPOSE

To assess the biocompatibility of 3 hydrophilic acrylic intraocular lenses (IOLs) by evaluating the postoperative cell reaction on the IOL surface, anterior capsule opacification (ACO) rate, and presence of membrane growth over the anterior IOL surface.

SETTING

University Eye Clinic of Trieste, Trieste, Italy.

METHODS

In this prospective study, 73 patients were randomized to receive 1 of 3 types of hydrogel IOLs after phacoemulsification: Storz Hydroview H60M, Corneal ACR6D, or Ioltech Stabibag. To analyze and photograph the anterior IOL surface, slitlamp biomicroscopy and specular microscopy were performed 7, 30, 90, and 180 days after surgery. Small, epithelioid, and giant inflammatory cell reaction was evaluated. In addition, ACO and membrane growth on the anterior IOL surface were assessed.

RESULTS

Low inflammatory cell adhesion was observed on the anterior surface of all 3 IOLs. The Stabibag group had a significantly higher grade of small inflammatory cell reaction 7 and 30 days after surgery. A significantly higher rate of ACO was observed in the ACR6D group. The Hydroview and ACR6D groups had a significantly higher percentage of membrane growth from the capsulorhexis edge onto the anterior IOL surface than the Stabibag group.

CONCLUSIONS

Clinically, the 3 hydrophilic IOLs behaved in a different manner, showing the different forms of biocompatibility. Results indicate that a different chemical composition determines correspondingly different protein absorption on IOL surfaces. This might result in a different adhesion pattern and spreading of lens epithelial and inflammatory cells.

Modulating fibroblast cell proliferation with functionalized poly(methyl methacrylate) based copolymers: chemical composition and monomer distribution effect

Poly(methyl methacrylate)-based terpolymers bearing sulfonate and carboxylate groups have been synthesized by radical copolymerization leading to polymers with random distributions of ionic monomer units. Fibroblast cells were seeded on terpolymers of various molar compositions of ionic groups. Kinetics of the cell proliferation were examined and systematically compared to the nonfunctionalized control polymer, poly(methyl methacrylate). Modulation of cell proliferation was observed on 15% ionic monomer content copolymers of various compositions (R = COO(-)/(COO(-) + SO(3)(-)) and varies from 0 to 1). The inhibition percentage of cell proliferation calculated for each polymer by comparison to the cell proliferation on the control was plotted against R and gave a maximum value for R close to 0.55. Copolymers with ionic group contents higher or lower than 15% exhibit inhibition percentages fitting with those previously observed for the same R values, showing that the hydrophilic properties are not sufficient to explain the modulation effect of this material toward cells. Moreover, for each polymer tested, cells, even if inhibited in growth, were shown to be viable, indicating that the synthesized terpolymers exhibit cytostatic properties excluding any cytotoxic effect. Such polymers may be used for the fabrication of biocompatible intraocular lenses and prevent secondary cataract.

Inflammatory cell adhesion and surface defects on heparin-surface-modified poly(methyl methacrylate) intraocular lenses in diabetic patients

PURPOSE

To evaluate the incidence of surface scratches on heparin-surface-modified (HSM) poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) and the possible influence of these alterations on the biocompatibility of HSM PMMA.

SETTING

University Eye Clinic of Trieste, Trieste, Italy.

METHODS

Twenty-six diabetic patients had phacoemulsification and implantation of an HSM PMMA IOL (809C, Pharmacia & Upjohn). Patients with proliferative diabetic retinopathy or iridopathy were excluded from the study. On postoperative days 7, 30, 90, and 180, specular microscopy was performed to study and photograph the anterior IOL surface. The presence of scratches on the anterior IOL surface was assessed and the inflammatory cell reaction noted and graded using a semiquantitative scale. Finally, the location of the inflammatory cells in relation to the surface scratches was established.

RESULTS

Scratches and other surface defects were found in 88.4% of cases. All patients had small cells on the IOL surface 7 days after surgery. At 30 days, small cells were observed in 88.4% of cases. The inflammatory cells were mainly located inside the scratches rather than throughout the IOL surface.

CONCLUSIONS

This in vivo cytology study provides further evidence of the effectiveness of heparin surface modification in improving the biocompatibility of PMMA. In diabetic patients, inflammatory cells adhered to the exposed PMMA surface more than to the HSM surface, suggesting that the use of HSM PMMA in patients with conditions predisposing them to increased postoperative blood-aqueous barrier breakdown is beneficial.

Pit defects on the anterior surface of hydrophilic foldable intraocular lenses

A series of pits varying in depth and size appeared on the anterior surface of hydrogel intraocular lenses (IOLs) soon after they were implanted. In all cases, the pits increased in size but not in number during a 1 year follow-up. The origin of the pit defects is unknown and does not seem related to inflammatory or lens epithelial cell activity. Hydration of the IOL could be a cause even if a manufacturing defect were present. This IOL surface alteration did not seem to impair visual function or cause visual disturbances.

Effect of heparin-surface-modified intraocular lenses on postoperative inflammation after phacoemulsification: a randomized trial in a United States patient population. Heparin-Surface-Modified Lens Study Group

OBJECTIVE

To compare postoperative inflammation occurring with heparin-surface-modified (HSM) versus non-HSM polymethyl methacrylate intraocular lenses (IOLs) after phacoemulsification.

DESIGN

Randomized, double-masked, multicenter, parallel trial.

PARTICIPANTS

A total of 367 patients, consisting of routine (n = 220), glaucoma (n = 58), and diabetes (n = 89) patients, from eight US medical centers.

METHODS

Patients were observed for 1 year after phacoemulsification and lens implantation (week 1, months 1, 3, 6, 12).

MAIN OUTCOME MEASURES

Primary measures of postoperative inflammation defined as the presence of giant cells on the lens surface via specular micrography and cellular deposits via slit-lamp examination.

RESULTS

The cross-sectional analyses showed that consistently fewer routine patients with HSM lens implants had giant cells on the IOL than those with non-HSM lens implants across all follow-up visits. The statistical significance (P < 0.05) was observed at all visits except month 12 for routine patients. The diabetes patients also demonstrated the same giant cell difference, and the statistical significance was observed at all visits including month 12. A similar trend was also observed in the glaucoma patients, with statistical significance only at the 3-month visit. For cell deposits, significant differences in favor of the HSM lens (P < 0.05) were observed at 3 months among routine and diabetes patients, and at 3 and 6 months among glaucoma patients. A longitudinal data analysis using the generalized estimating equation approach indicated statistically significant treatment effect of HSM lenses in reducing inflammation in all patients except for cellular deposits in diabetes patients. In all patient groups, sight-threatening complications were not reported either more frequently or with more severity than normally expected for patients who have undergone cataract extraction and IOL implantation.

CONCLUSIONS

The present study, the only one to have used phacoemulsification in virtually all patients (211/220 [96%] routine, 57/58 [98%] glaucoma, and 84/89 [94%] diabetes) is the largest to evaluate and compare concurrently routine, glaucoma, and diabetes patients. It is also the first US patient population study to document that heparin surface modification reduces postoperative inflammatory responses, as measured by specular micrography and slit-lamp examination, especially in the early postoperative period.

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.

Reduced basal and stimulated leukocyte adherence in tumor endothelium of experimental pancreatic cancer

BACKGROUND

The interaction between immunocompetent cells and tumor endothelium is essential for an effective immunological response. In the present study, we evaluated resting and CD11b/CD18-mediated leukocyte adhesion in tumor vessels of experimental pancreatic cancer and in healthy pancreatic venules in the rat.

METHODS

Solid tumor fragments (1 mm3) were interposed intrapancreatically between inert transparent polymethylmetacrylate plates for intravital microscopy (n = 12) by which tumor microcirculation, leukocyte-tumor-endothelium interaction, and the effect of the chemoattractants N-formyl-methioninleucylphenylalanine (fMLP) and platelet-activating factor (PAF) on leukocyte adherence was investigated.

RESULTS

Leukocyte adhesion in pancreatic tumor vessels was significantly reduced compared to healthy pancreatic venules. Both fMLP and PAF dramatically increased leukocyte adherence in normal pancreatic venules. No change in leukocyte adhesion was present in tumor vessels after exposure to these chemotactic substances.

CONCLUSION

Resting and stimulated integrin-dependent leukocyte adhesion is strongly reduced in malignant vessels of experimental pancreatic cancer, which may be an important mechanism to escape immune control.

Phacoemulsification and modern cataract surgery

The techniques and results of cataract surgery have changed dramatically during the past three decades. In the USA, we have moved from intracapsular cataract extraction as the preferred technique to almost exclusively extracapsular techniques. Smaller incisions have become the standard, with phacoemulsification now being the method of choice for most surgeons. Along with these advances have come improved intraocular lens materials and designs, especially well suited for use with smaller incisions. Phacoemulsification as a method to remove the cataractous lens was first proposed more than 20 years ago. Advances in techniques and equipment have led to a dramatic increase in the popularity of phacoemulsification with increased safety and efficiency. Viscoelastic agents have been developed synchronously with modern phacoemulsification techniques, playing an integral role in the success of this new technology. Improved surgical techniques for removing the anterior lens capsule have decreased the incidence of both intraoperative and postoperative capsular complications. Nucleus removal, formerly performed primarily in the anterior chamber, is now performed in the posterior chamber, decreasing damage to the corneal endothelium. Improved wound construction allows many wounds to be left unsutured, and smaller wounds allow shorter recovery time and greater intraoperative control and safety. Intraocular lenses can have smaller optic sizes and still maintain accurate centration. Foldable intraocular lenses can take advantage of the smaller incision, even further shortening the time to visual recovery. Continual evolution of this technology promises to further improve patient outcomes after cataract surgery.

Course of postoperative inflammation after implantation of 4 types of foldable intraocular lenses

PURPOSE

To compare the course of postoperative inflammation after small incision cataract surgery with implantation of 4 types of foldable intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, University Hospital of Vienna, Austria.

METHODS

One hundred twenty eyes were prospectively randomized to receive a foldable silicone (Pharmacia 920), hydrogel (Bausch & Lomb Hydroview), methyl methacrylate/hydroxyethyl methacrylate (Mentor MemoryLens), or acrylic (Alcon AcrySof) IOL. All surgery was performed by the same experienced surgeon using a standardized surgical protocol: clear corneal incision, capsulorhexis, phacoemulsification, and in-the-bag implantation of the IOL. All patients received standardized postoperative medication and follow-up. Postoperative inflammation was evaluated by measuring aqueous flare preoperatively and 1, 3, 7, 14, 28, 90, and 180 days after surgery using the Kowa 1000 laser flare-cell meter.

RESULTS

Except on the first day after surgery, when the AcrySof group had higher flare values than the other groups (P = .0265), no significant differences were found up to 6 months. Re-establishment of the blood-aqueous barrier was similar in eyes with the AcrySof, Hydroview, and MemoryLens IOLs; the course of postoperative inflammation was different in eyes with the silicone IOL.

CONCLUSION

Comparison of postoperative flare values after implantation of 4 foldable IOLs showed no clinically relevant differences in the course of postoperative inflammation.

Effect of intraocular lens and anterior capsule opening type on posterior capsule opacification

PURPOSE

To determine the effect of intraocular lens (IOL) type and anterior capsulectomy technique on the incidence of posterior capsule opacification.

SETTING

Department of Ophthalmology, Medical Faculty, University of Ondokuz Mayis, Samsun, Turkey.

METHODS

Three hundred two eyes of 294 patients were examined retrospectively after IOL implantation in the capsular bag performed between February 1991 and November 1996. Patients were divided into 3 groups according to IOL type: poly(methyl methacrylate) (PMMA); heparin-surface-modified PMMA (HSM PMMA); plate-haptic silicone. Envelope capsulectomy or continuous curvilinear capsulorhexis (CCC) was used. Mean follow-up was 27 months (range 12 to 33 months).

RESULTS

Posterior capsule opacification developed in 47 cases (15.6%): 21.7% in the PMMA lens group after planned extracapsular cataract extraction (ECCE), 17.4% in the HSM PMMA lens group after planned ECCE, and 7.7% in the plate-haptic silicone lens group after phacoemulsification. Posterior capsule opacification occurred less in patients who had anterior capsulectomy using the CCC technique (11.5%) than in those having an envelope capsulectomy (24.5%) (P < .05). Posterior capsule opacification was significantly less in eyes with a capsular-bag-fixated plate-haptic silicone lens than in those with a PMMA or HSM PMMA IOL (P < .05).

CONCLUSION

This study demonstrated that the anterior capsulectomy technique and the IOL type influence the incidence 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.

Endophthalmitis after cataract surgery: risk factors relating to technique and events of the operation and patient history: a retrospective case-control study

OBJECTIVE

This study aimed to investigate the relationship between postoperative endophthalmitis and current changes in the cataract operative technique.

DESIGN

A retrospective case-control study.

PARTICIPANTS

The 22,091 cataract operations performed from 1990 through 1993 at St Eriks Hospital formed the basis for this investigation. In a random fashion, 220 control subjects were selected to be compared with the endophthalmitis cases.

MAIN OUTCOME MEASURES

Numerous variables pertaining to the cataract extraction procedure and to the ocular and general health of patients with cataracts were analyzed regarding the development of postoperative intraocular infection. Patient age, presence of diabetes or immunosuppression, type of cataract extraction and intraocular lens (IOL), and intraoperative or postoperative complications were the principal variables assessed.

RESULTS

Fifty-seven patients with endophthalmitis were diagnosed, resulting in an overall frequency of 0.26%. Immunosuppressive treatment (P = 0.019), wound abnormality (P = 0.03), and the use of IOLs without a heparinized surface (P = 0.0023) were the only significant risk factors found in a logistic regression model.

CONCLUSIONS

The results suggest that cataract operating practice may alter the risk for endophthalmitis in that implanting a heparinized IOL and creating a tight section both seem to provide protection against this dreaded complication. Regarding patient history, an increased susceptibility was found among subjects treated with immunosuppressants. Designing a prophylactic protocol that protects against endophthalmitis more efficiently than did the study prophylaxis of 20 mg of subconjunctival gentamicin, is important not only for this patient subgroup but also for the cataract operated population at large.

Measurement of electrostatic charge on intraocular lenses

PURPOSE

An electronic meter that measures electrostatic charge was designed and built. The hypothesis tested was that an intraocular lens (IOL) attains a charge during handling in the operating theatre and that washing the IOL with balanced salt solution (BSS) would result in a reduction in the surface charge. Once exposed to the air a charged IOL may attract particulate matter to its surface before implantation into the eye.

METHODS

This experiment was performed in the operating theatre under sterile conditions mimicking cataract surgery. The lens box was opened onto a trolley and the lens container opened by a scrubbed assistant. The operator (also scrubbed) removed the lens with MacPherson's forceps. The charge on the lens was then measured without delay, or after the lens had been washed with 1-2 ml of BSS.

RESULTS

The mean charge on unwashed lenses was 1.43 x 10(-10) C (n = 12) and on washed lenses was 0.59 x 10(-10) C (n = 10). The difference in the charges was significant (p = 0.03, unpaired t-test).

CONCLUSION

Washing of an IOL prior to implantation will reduce the surface charge and is therefore also likely to reduce the chance of contamination.

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.

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 biocompatible 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.

The effect of heparin-surface-modification on scar-tissue formation around a subconjunctival polymethylmethacrylate implant in the rabbit

PURPOSE

Excessive scar tissue formation around ocular drainage implants is a common cause for implant failure. The purpose of this study was to evaluate the effect of heparin-surface-modification of a subconjunctival polymethylmethacrylate implant on scar-tissue formation in the rabbit eye.

METHODS

Plain and heparin-surface-modified polymethylmethacrylate implants were implanted subconjunctivally in the eyes of 13 rabbits in two groups consisting of 8 and 5 animals. In the latter group the implants were in contact with aqueous humour through a fistula into the anterior chamber.

RESULTS

Both unmodified and heparin-surface-modified polymethylmethacrylate implants were well tolerated. In histological sections studied by both light microscopy and transmission electron microscopy, heparin-surface-modification of polymethylmethacrylate implants seemed to diminish the formation of scar tissue around the subconjunctival implants.

CONCLUSION

Heparin-surface-modification of polymethylmethacrylate implants could provide one way to affect the formation of excessive fibrous tissue around ocular drainage implants.

A retrospective analysis of heparin-surface-modified intraocular lenses versus regular polymethylmethacrylate intraocular lenses in patients with uveitis

BACKGROUND

Several studies described the benefits of the heparin-surface-modified intraocular tens (HSM IOL) with regard to the reduced inflammation in routine extracapsular cataract extractions. However, limited information is available about the advantages of the HSM IOL in patients with an intraocular inflammation.

AIM

To assess the eventual benefits of the HSM IOL compared to the regular polymethylmethacrylate intraocular lens (PMMA IOL) in patients with uveitis.

METHODS

A retrospective study of 43 patients with uveitis of various origins who underwent an extracapsular cataract extraction (24 with HSM, 19 with PMMA IOL). The activity of intraocular inflammation, visual acuity, eventual complications, and medications were examined. Standardized follow-up dates were used (before surgery, one and fourteen days, five and eleven months after surgery.)

RESULTS

No difference in the inflammatory, activity was noted between HSM and PMMA groups; neither at short term clinical evaluation, nor at five months after surgery. Despite a slightly better visual acuity in the HSM group before surgery, no long term differences were observed. After surgery the increase in visual acuity was similar for both groups, as well as the frequency of cystoid macular oedema (CMO) and synechiae. Fewer patients in HSM group required Nd:YAG posterior capsulotomy, but the difference was not significant.

CONCLUSION

No clinical advantage was found when the HSM IOL was compared with the regular PMMA IOL in 43 patients with uveitis.