Pathology of intraocular lenses in 33 eyes examined postmortem

Refractive Changes After Nd:YAG Capsulotomy in Pseudophakic Eyes

Purpose

To analyze refractive changes after neodymium: yttrium-aluminum-garnet (Nd:YAG) posterior capsulotomy in pseudophakic eyes.

Patients and Methods

Patients who underwent Nd:YAG capsulotomy after cataract surgery from January 2013 to April 2022 were included in this retrospective study. Sphere, cylinder, spherical equivalent (SE), axis, and corrected distance visual acuity (CDVA) were compared pre- and postoperatively in 683 eyes of 548 patients at one month (n = 605 eyes) and one year (n = 211 eyes). Patients with both one-month and one-year follow-ups (n = 133) were also compared. Eyes were stratified into single-piece (n = 330), three-piece (n = 30), and light adjustable lenses (LALs) (n = 16). Pre- and postoperative measurements were analyzed within each group.

Results

Cylinder was significantly decreased at one-month (difference: 0.042±0.448 D, p = 0.006) and one-year (difference: 0.101±0.455 D, p = 0.003) compared to preoperative measurements. No significant change in sphere or axis was observed at follow-up visits (p > 0.05). CDVA significantly improved at both time points (p < 0.05). No significant change in any parameters between the one-month and one-year groups was observed (p > 0.05). There was significant improvement in CDVA in the single and three-piece lens groups (p < 0.0001 and p = 0.026, respectively), with no change in the LAL group (p > 0.05).

Conclusion

There were no changes in sphere, axis, or spherical equivalent after Nd:YAG capsulotomy. However, cylindrical error and CDVA were significantly better after the procedure. Lens type did not impact refractive parameters postoperatively.

Optical coherence tomography for an in-vivo study of posterior-capsule-opacification types and their influence on the total-pulse energy required for Nd:YAG capsulotomy: a case series

Background

Posterior capsule opacification (PCO) is the most common post-operative complication associated with cataract surgery and is mostly treated with Nd:YAG laser capsulotomy. Here, we demonstrate the use of high-resolution spectral-domain optical coherence tomography (OCT) as a technique for PCO analysis. Additionally, we evaluate the influence of PCO types and the distance between the intraocular lens (IOL) and the posterior capsule (PC), i.e., the IOL/PC distance, on the total-pulse energy required for the Nd:YAG laser posterior capsulotomy.

Methods

47 eyes with PCO scheduled for the Nd:YAG procedure were examined and divided into four categories: fibrosis, pearl, mixed type and late-postoperative capsular bag distension syndrome. Using custom-made computer software for OCT image analysis, the IOL/PC distances in two dimensions were measured. The IOL/PC distances were compared with those of a control group of 15 eyes without PCO. The influence of the different PCO types and the IOL/PC distance on the total-pulse energy required for the Nd:YAG procedure was analyzed.

Results

The total-pulse energy required for a laser capsulotomy differs significantly between PCO types (p = 0.005, Kruskal-Wallis test). The highest energy was required for the fibrosis PCO type, followed by mixed, pearl and late-postoperative capsular bag distension syndrome. The IOL/PC distance also significantly influenced the total-pulse energy required for laser capsulotomy (p = 0.028, linear regression). Lower total-pulse energy was expected for a larger IOL/PC distance.

Conclusions

Our study indicates that the PCO types and the IOL/PC distance influence the total-pulse energy required for Nd:YAG capsulotomy. The presented OCT method has the potential to become an additional tool for PCO characterization. Our results are important for a better understanding of the photodisruptive mechanisms in Nd:YAG capsulotomy.

Long-term pathological follow-up of 2-loop iridocapsular intraocular lens

We analyzed an enucleated postmortem eye from an 86-year-old donor who had a 2-loop iridocapsular intraocular lens (IOL) that had been implanted at least 30 years earlier. High-frequency ultrasound showed a relatively well-centered iris-supported optic in front of the pupil. Gross and light microscopic analyses of the eye and the IOL showed loop fixation outside the capsular bag remnants, a thickened cornea, mild attenuation of the corneal endothelium, multiple areas of iris trauma secondary to haptic abrasion, fragments of iris tissue attached to the haptics, as well as pigment dispersion within the eye with pigmented epithelial cells attached to the IOL haptics. Histopathological examination of the posterior segment was unremarkable.

Endophthalmitis due to exposure of anterior chamber intraocular lens haptic tip

After bilateral implantation of an angle-supported anterior chamber intraocular lens (AC IOL) in an allergic patient, the haptic tips were exposed through the limbus in the left eye. Endophthalmitis developed in the eye and was treated by pars plana vitrectomy, IOL extraction, and intravitreal antibiotic injection. Haptic repositioning was performed in the right eye. In this report, we assess the possibility that exposure of the angle-supported AC IOL haptics caused the endophthalmitis. We hypothesized that vigorous rubbing of the eye of the atopic patient might cause limbal erosion that could lead to exposure of the angle-supported AC IOL haptic through the limbus.

Histopathologic study of changes occurring in eyes with intraocular lens implantation: autopsy eyes, enucleated eyes and corneal buttons

The clinicopathologic findings in 17 eyes which were surgically enucleated or removed at autopsy as well as the histopathology of 72 corneal buttons removed from eyes with intraocular lenses are described. In four of five autopsy eyes the intraocular lens was well tolerated; however, in all cases, changes related to the pseudophakos were found. In seven of 12 surgically enucleated eyes, postsurgical bacterial or fungal endophthalmitis had developed. On histopathological examination, one eye revealed clinically unsuspected endophthalmitis phacoanaphylactica after extracapsular cataract extraction and intraocular lens implantation. In two cases, choroidal melanoma became evident after cataract extraction and insertion of a pseudophakos. In both cases preoperative ultrasonography was limited to A-scan axial measurements. The 72 corneal buttons were removed from patients with pseudophakic bullous keratopathy; histologically the most striking findings were guttata-like changes in 50% of the specimens and retrocorneal membranes in 13.9% of the specimens.

Pseudophaco--anaphylactic endophthalmitis? P.M.M.A. related

The pathological findings of pseudophacoanaphylactic endophthalmitis are described in a patient with a combined trabeculectomy, extracapsular cataract extraction and an "in-the-bag" posterior chamber lens implant, and who developed sympathetic ophthalmitis following a perforating eye injury within hours of his operation. Apart from the typical sympathetic histological findings, the eye revealed a pseudophaco-anaphylactic endophthalmitis reaction which appeared to be totally related to the polymethylmethacrylate (P.M.M.A.) optic. The "in-the-bag" polypropylene closed loops revealed no significant histological reaction.

Cellular deposits on intraocular lenses

We examined cellular deposits on 14 intraocular lenses (IOL) that were removed after implantation for a variety of clinical reasons. Five of the lenses were cultured to evaluate the growth potential of preexisting cells on the IOLs. The most common cells found were iris pigment epithelial cells. The thickest membranes were probably formed by iris stromal cells. Other cellular deposits included macrophages, multinucleated foreign body giant cells, lens epithelial cells, squamous epithelial ingrowth, red blood cells, uveal melanocytes, and vitreous strands. Cells around the IOL had only limited growth in tissue culture. We propose that a continuous influx of inflammatory cells in conjunction with a disruption of the blood-aqueous barrier may be an important pathogenetic mechanism for the production of thick secondary membranes around an IOL.

Successful intraocular lens implantation: a histological and scanning electron microscopic study of four cases

The histological findings in four globes obtained at autopsy from clinically uncomplicated cases with intraocular lens implants, one glass posterior chamber and three anterior chamber lenses consisting of two pupillary fixated and one "in-the-bag" fixated Binkhorst lens, are reported. Minimal changes could be detected in the tissues with which the implants were in contact. Scanning electron microscopy of the cornea in the three anterior chamber implants showed a loss of endothelial cells in the axial region of roughly 30-50%. There was marked vertical disparity in the loss. Scanning microscopy of the implants showed evidence of surface degradation of the nylon loops of all the anterior chamber implants.

Pseudophakic corneal edema: A review of mechanisms and treatments

PURPOSE

To review the pathological mechanisms and treatments for pseudophakic corneal edema (PCE), one of the most common indications for penetrating keratoplasty.

METHODS

The literature was examined for the molecular biology associated with PCE and for the surgical and medical treatments for this disorder.

RESULTS

The incidence of PCE has recently been decreasing because of improved surgical instrumentation, including improvements in intraocular lens designs that cause less trauma to the corneal endothelium. Extracellular matrix and growth factor abnormalities occur in PCE corneas and recently, the role of aquaporins, which are involved in the regulation of fluid movement across cells, has been investigated.

CONCLUSIONS

Although newer treatment options have been suggested, penetrating keratoplasty still remains the most definitive treatment and has the highest success rate.

Relationship between posterior capsule opacification and intraocular lens biocompatibility

The type of healing process that occurs in response to cataract surgery and intraocular lens (IOL) implantation is dependent on a complex set of variables. Their interactions determine whether or not optical clarity is restored as a result of this procedure. In this process, wound healing entails cells undergoing either epithelial-mesenchymal transition, resulting in the generation of fibroblastic cells and accumulation of extracellular matrix, or lenticular structure formation. Such desperate cellular behaviors are regulated by the localized release of different cytokines, including transforming growth factor beta and fibroblast growth factors, which can result in post-operative capsular opacification. Other factors affecting the biological and mechanical outcome of IOL implantation are its composition, surface properties and shape.

Lens epithelial cell outgrowth on 3 types of intraocular lenses

PURPOSE

To compare the outgrowth of lens epithelial cells (LECs) on 3 types of intraocular lenses (IOLs) to determine the influence of lens material and lens design (optic edge) on this phenomenon.

SETTING

Department of Ophthalmology, University of Vienna, Medical School, Vienna, Austria.

METHOD

Ninety eyes scheduled for cataract surgery were included in a prospective comparative study. A standardized surgical procedure was performed by 1 experienced surgeon. Patients received 1 of 3 types of posterior chamber IOLs of similar design with a 6.0 mm optic and poly(methyl methacrylate) haptic: AcrySof (Alcon), HydroView (Bausch & Lomb), or Sensar (Allergan). Each IOL type was implanted in 30 eyes. Postoperative biomicroscopic examinations were performed 1, 3, 7, 30, 90, and 180 days and 1 year after surgery. Lens epithelial cells in each quadrant of the anterior lens surface were subjectively graded. The product with the highest density and the number of quadrants with this density were used to measure LEC outgrowth.

RESULTS

Statistically significant differences (P <.05) were seen between the hydrophilic IOL and the 2 hydrophobic lenses from day 30 until the final examination. The HydroView lens had a higher number of LECs on its anterior surface than the AcrySof or Sensar IOL. There were no statistically significant differences between the 2 acrylic IOLs at any measurement.

CONCLUSION

The findings suggest that lens surface properties have a greater influence on LEC outgrowth than lens design (ie, sharp optic edge).

Intraocular lens complications requiring removal or exchange

Intraocular lens (IOL)-related complications are caused primarily by mechanical trauma, inflammatory or infectious complications, or optical problems. Complications may occur at the time of surgery or be the result of an ongoing postoperative process. Mechanical and inflammatory injury may produce corneal decompensation, cystoid macular edema, hyphema, uveitis, and glaucoma, causing reduced vision and in some cases chronic pain. Optical problems may be due to a wrong power of the IOL or to postoperative decentration or dislocation of the lens. Ophthalmologists should be aware of the indications for IOL removal or exchange in those patients who have ongoing IOL-induced injury or impairment. Removal or exchange of an IOL frequently involves a complex decision-making process and is often associated with immense technical challenge. Various medical and surgical treatments may be tried to correct IOL problems before the decision is made to remove or exchange the lens.

Nd:YAG laser removal of pupillary membranes developed after ECCE with PC-IOL implantation

PURPOSE

To define the frequency of development of pupillary membranes after ECCE with PC-IOL implantation, and to remove the pupillary membranes using the Nd:YAG laser.

METHODS

From 400 patients who had undergone ECCE and were free from local or systemic illness affecting the blood-ocular barrier, 20 eyes developed pupillary membranes Nd:YAG laser was used to remove these pupillary membranes.

RESULTS

The frequency of pupillary membranes was found to be 5% (9.8% in pex eyes and 3.3% to the non-pex eyes). Visual acuity improved in 17 eyes by 2 to 5 Snellen lines. No serious complications were observed, endothelium inclusive.

CONCLUSION

Pseudoexfoliation might play a significant role in the development of postoperative pupillary membranes which could be successfully treated with the use of Nd:YAG laser. The safety of the procedure has to be evaluated in relation to the corneal endothelium damage in long-term.

Posterior capsule opacification and capsulotomy rates with taco-style hydrogel intraocular lenses

PURPOSE

To evaluate posterior capsule opacification (PCO) formation and neodymium: YAG (Nd:YAG) laser capsulotomy results in eyes with an logel intraocular lens (IOL).

SETTING

First University Hospital, Vienna, Austria.

METHODS

A retrospective study was done of 108 eyes with one of three types of an logel IOL that had decreased vision from PCO and required posterior capsule discission.

RESULTS

In general, in eyes with sulcus-placed IOLs, a Soemmering's ring formed and the capsulorhexis rim tightly adhered to the posterior capsule, sealing the capsular bag periphery. Elschnig pearls had broken the barrier, invading the retrolental space. In eyes with bag-placed IOLs, there was a gap between the IOL and posterior capsule in which Elschnig pearls had accumulated. This gap frequently extended beneath the flanges to the periphery of the capsular bag, allowing residual lens epithelial cells to proliferate and migrate centrally.

CONCLUSION

The logel lenses led to a high incidence of regeneratory PCO within the gap between the lens and capsule that might be the result of the properties of the lens' hydrogel material rather than its design.

Pupil abnormalities on the first postoperative day after cataract surgery

Most, if not all, ophthalmologists strive to achieve a round pupil after cataract surgery with posterior chamber lens implantation. The presence of pupil abnormalities and iris modifications is cosmetically undesirable and may affect the quality of postoperative vision. The pupillary motility may be changed which will in turn affect both pupillary light reflexes and pupillary dilatation during fundus examination. In this paper, we prospectively studied 2 groups of patients who underwent uncomplicated cataract surgery with posterior chamber lens implantation; 100 patients who had planned extracapsular cataract extraction (ECCE), and 130 patients who underwent phacoemulsification. On the first postoperative day, we found a 16% rate of pupil abnormalities in the group which underwent ECCE surgery while only 5.3% of the phacoemulsification group had pupil abnormalities. There were different causes in which the two groups. The most common cause of pupil abnormality after ECCE was due to iris sphincter rupture, whereas the most common cause after phacoemulsification was due to iris trauma during phacoemulsification. These pupil abnormalities are the direct consequence of factors in surgery and we suggest ways to minimize the occurrence of such abnormalities in cataract surgery.

Lens epithelial cell outgrowth and matrix formation on intraocular lenses in rabbit eyes

PURPOSE

To evaluate the presence and distribution of lens epithelial cells (LECs) and extracellular matrix on intraocular lenses (IOLs) implanted in the capsular bag in rabbit eyes.

SETTING

Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan.

METHODS

Five adult albino rabbits had phacoemulsification and IOL implantation in both eyes. Two or 11 months later, the animals were killed by intravenous pentobarbital. The IOLs were removed and observed under scanning and transmission electron microscopy.

RESULTS

In addition to the macrophages and giant cells on the IOLs, all eyes had a monolayer of flattened cells growing out from the residual anterior lens capsule and a fibrous meshwork of extracellular matrix. Unlike those of a macrophagic origin, these cells had no central cytoplasmic elevation of nuclei and few cell surface microvilli and were considered to be proliferating LECs.

CONCLUSION

Lens epithelial cells are involved in the eye's cellular reaction to IOLs and in the formation of extracellular matrix on IOLs. Further study of LEC behavior on IOLs should be done to improve IOL biocompatibility.

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

Evidence that poly(methyl methacrylate) (PMMA) is not inert in the eye has led to the introduction of intraocular lens (IOL) surface modification. In this prospective, double-blind, randomized study, we evaluated the effects of heparin surface modification (HSM) on anterior segment inflammation for one year after endocapsular cataract surgery. Fifty-four eyes were randomized to receive an HSM IOL (29 eyes) or a PMMA IOL (25 eyes) and were assessed postoperatively by corneal endothelial photography, laser flare and cell measurements, fluorophotometry, and IOL surface specular microscopy. Corneal endothelial loss, mean aqueous flare and cells, and fluorophotometry did not differ significantly between the groups, although fewer eyes in the HSM group had high flare values on the first postoperative day. The number of giant cells was significantly less in the HSM group for up to one year after surgery. Although there was no statistical difference in overall visual outcome, more patients in the HSM group (17%, 5/29) achieved a postoperative visual acuity of 20/15 than in the PMMA group (0). These results demonstrate that HSM enhances IOL biocompatibility and these effects are detectable in the low-risk, normal eye.

Natural history of cellular deposits on the anterior intraocular lens surface

Previous cytopathological studies have demonstrated the presence of cellular deposits on the poly(methyl methacrylate) (PMMA) intraocular lens (IOL) surface. In this prospective study, IOL surface specular microscopy was used to document the natural history of these deposits in the first year following PMMA IOL implantation. Intraocular lens surface specular microscopy was performed 1, 3, 6, and 12 months after endocapsular cataract surgery in 27 otherwise normal eyes. Postoperatively, IOLs were assessed for the presence of inflammatory cells, with the number of cells graded from 0 (none) to 4 (many). Two inflammatory cell types were visualized: small and giant cells. Small cells were found on 81.5% of IOLs at 1 month, 73.1% at 3 months, and 30.4% at 12 months. Small cells were found in only small numbers (peak mean cell score of 1.26 +/- 0.94 at 1 month). Giant cells were found on 59.3% of lenses at 1 month, 73.1% at 3 months, and 39.1% at 12 months. The number of giant cells on each lens peaked at 3 months (mean cell score 2.0 +/- 1.55), when 50% of lenses achieved a giant cell score of 3 or 4. Inflammatory cell deposits are, therefore, a normal occurrence on the PMMA IOL surface for up to 1 year after surgery. This cellular response consists of two distinct processes: a small cell response, which peaks by 1 month, and a later giant cell response, which peaks at 3 months.

Melanin-containing hydrogel intraocular lenses: a histopathological study in animal eyes

Poly(2-hydroxyethyl methacrylate) hydrogel intraocular lenses, containing adrenochrome-melanin, were manufactured and implanted in animal eyes in order to assess the effect of melanin upon (a) biocompatibility of implants with the eye tissues, and (b) fibrous proliferation of lens epithelium responsible for the opacification of the posterior capsular membrane. An equal number of control lenses were also implanted. The animals were followed up for durations up to two years, and a detailed histopathological examination of the eyes was performed subsequent to their enucleation. The postoperative complications were minor and probably caused by surgical trauma. The study failed to give any indication of the postulated antiproliferative activity of adrenochrome-melanin since minimal capsular opacification occurred in the operated eyes, regardless of the presence of melanin.

Collagen types in human posterior capsule opacification

The fibrous type of human posterior capsule opacification was examined by electron microscopy and immunoelectron microscopy to determine which types of collagen were present. The opacification consisted of lens epithelial cells and a large amount of extracellular matrix. The extracellular matrix comprised collagen fibrils and basal lamina-like material. Immunoelectron microscopy revealed that collagen types I, III, and IV were present. Types I and III were localized to the collagen fibrils. Type IV was present in the basal lamina of the lens epithelial cells and in the basal lamina-like material of the extracellular matrix.

The diameter of the ciliary sulcus: a morphometric study

Based on a precise definition of boundaries of the ciliary sulcus, a new anatomical method was used to measure the diameter of the ciliary sulcus in postmortem eyes. In each of 41 globes, 24 different ciliary sulcus diameters were measured and were compared with the axial length, measured by ultrasonography. The mean ciliary sulcus diameter was 11.25 mm (SD = 0.38 mm). By linear regression, the axial length values were significantly correlated with ciliary sulcus diameters. In addition, our data suggest that existence of two groups of eyes differentiated exclusively by the diameter of the ciliary sulcus, independent of the axial length. We propose that the displacement of the pars plicata corporis ciliaris from the peripheral iris to the iris root during the embryonic period may be incomplete in eyes of shorter axial length. The findings of the present study may play a role in cataract surgery in which an intraocular lens is inserted into the ciliary sulcus.

Clinicopathologic study of the effect of radial tears and loop fixation on intraocular lens decentration

PURPOSE

The purpose of this study is to determine the effect of loop fixation and anterior capsular tears on intraocular lens (IOL) decentration.

METHODS

A retrospective measurement of IOL decentration was performed on 144 human eyes with posterior chamber (PC) IOLs obtained after death.

RESULTS

Decentration in eyes with asymmetrical bag-sulcus fixation (mean +/- standard deviation, 0.64 +/- 0.39 mm) was significantly higher than eyes with symmetrical fixation. In the presence of radial tears, symmetrically fixated IOLs in either the capsular bag or the ciliary sulcus decentered to a similar degree, 0.35 +/- 0.25 mm and 0.4 +/- 0.26 mm, respectively. The least decentration was observed with capsular fixation and no radial tears (0.18 +/- 0.09 mm). This was significantly less decentration than with any other form of fixation in the presence of radial tears.

CONCLUSION

This study shows that capsular fixation with no radial tears, as can be achieved by using the continuous curvilinear capsulorhexis, is associated with the least decentration.

Posterior capsule opacification

A complication of extracapsular cataract extraction with or without posterior chamber intraocular lens (PC-IOL) implantation is posterior capsule opacification. This condition is usually secondary to a proliferation and migration of residual lens epithelial cells. Opacification may be reduced by atraumatic surgery and thorough cortical clean-up. Clinical, pathological and experimental studies have shown that use of hydrodissection, the continuous curvilinear capsulorhexis and specific IOL designs may help reduce the incidence of this complication. Capsular-fixated, one-piece all-polymethylmethacrylate PC-IOLs with a C-shaped loop configuration and a posterior convexity of the optic are effective. Polymethylmethacrylate loops that retain "memory" create a symmetric, radial stretch on the posterior capsule after in-the-bag placement, leading to a more complete contact between the posterior surface of the IOL optic and the taut capsule. This may help form a barrier against central migration of epithelial cells into the visual axis. Various pharmacological and immunological methods are being investigated but conclusive data on these modalities are not yet available.

The Binkhorst Medal Lecture. Biologic relationship between poly(methyl methacrylate) intraocular lenses and uveal tissue

Implantation of a poly(methyl methacrylate) (PMMA) intraocular lens (IOL) after cataract surgery is associated with breakdown of the blood-ocular barrier and a foreign body inflammatory response. Although the material is biocompatible, it is not inert. The history of PMMA IOL implantation has reflected mechanical, chemical, and immunological interactions between the IOL and ocular tissues. The common link in these events is instability of the blood-ocular barrier. In this lecture, I discuss the nature of these interactions and present evidence that currently investigated methods of surface modification and capsular bag IOL implantation are effective in stabilizing the blood-ocular barrier.

The glaucomas in aphakia and pseudophakia

Intraocular pressure may become temporarily or permanently elevated at various intervals following cataract surgery. There are several mechanisms by which glaucoma develops as a complication of the cataract extraction itself. The presence of a pseudophakos may or may not contribute to the pathogenesis. Important diagnostic clues include the anterior chamber depth, the presence or absence of an iridectomy, gonioscopic findings, and the appearance of the optic nerve head. Life-long medical treatment is frequently justified, as alternative laser or surgical modalities may not be successful. The exact causes for high failure of filtration surgery in aphakic eyes is not clearly understood; scarring of the conjunctiva, the vitreous, and altered characteristics of the aqueous humor have all been incriminated. Current research to improve surgical success includes the development of effective artificial drainage implants or the use of pharmacologic modulators of wound healing, which promote filtration by preventing scar formation.

Iris modifications following extracapsular cataract extraction with posterior chamber lens implantation

We prospectively examined 94 eyes of 93 consecutive patients who had planned extracapsular cataract extraction or phacoemulsification with posterior chamber intraocular lens (IOL) implantation. The observed postoperative iris biomicroscopic modifications are described and classified. Iris synechial formation was more frequently observed in eyes with pseudoexfoliation syndrome, when an irregular anterior capsulotomy was performed, when the IOL was other than in the bag, and in cases of postoperative fibrinous exudation. Synechias occurred more frequently in intraoperatively injured iris areas. Pupil capture was the only postoperative iris modification that was observed to affect visual acuity. The maximal postoperative dilation was greater and the pupillary photic reaction was significantly less modified postoperatively (P = .0058) when the IOL was fixated within the capsular bag.

Experimental evaluation of a phakic anterior chamber implant in a primate model. Part II. Pathology

Anterior chamber intraocular lenses were implanted in 50 phakic primate eyes and followed by serial histopathology for two years. Significant observations included corneal endothelial alterations, haptic erosion into and encapsulation by peripheral iris and ciliary body, and chronic low grade inflammation.

Experimental evaluation of a phakic anterior chamber implant in a primate model. Part I. Clinical observations

Anterior chamber intraocular lenses were implanted in phakic cynomolgus monkey eyes and followed clinically over two years. Significant observations included erosion and/or uveal envelopment of the haptic and a decrease in endothelial cell counts. There was good positional stability, no significant inflammation, initial ocular hypotension that returned to normal intraocular pressure, and no evidence of cataracts or cystoid macular edema.

Recovery of the blood-aqueous barrier after cataract surgery

Following extracapsular cataract and posterior chamber implant surgery the sequential recovery of the blood-aqueous barrier was measured by anterior segment fluorophotometry. Postoperatively 49 (69.0%) out of 71 eyes (71 patients) had recovered at a uniform rate, re-establishing a normal blood-aqueous barrier by the end of the three-month study. In these eyes recovery of the blood-aqueous barrier was unaffected by the use of preoperative indomethacin, the surgeon, the type of section, or the type of fixation of the implant. In eyes recovering normally after cataract surgery the rate of recovery of the blood-aqueous barrier can be expressed by a in the equation a = (y-b)/x, in which y is the logarithm of the anterior chamber fluorescence, x is the time after surgery, and b is a constant for each patient which is the anterior chamber fluorescence measured immediately after surgery. This normal rate of recovery provides a baseline from which to assess surgical technique or postoperative medication.

Implantation of scleral-fixated posterior chamber intraocular lenses

A surgical technique for implanting a posterior chamber intraocular lens (IOL) in eyes without capsular or zonular support is presented. A 10-0 polypropylene suture attached to a standard needle is tied to the apex of each haptic and passed transclerally through the ciliary sulcus to secure the haptics at the 3 o'clock and 9 o'clock meridians. This technique produced good visual results in six aphakic patients who were contact lens intolerant, two patients in whom capsular or zonular rupture at the time of cataract surgery precluded standard nonsuture fixation techniques, one patient who had intracapsular cataract extraction for a subluxated, cataractous lens, and one patient who had secondary IOL implantation in combination with penetrating keratoplasty for aphakic bullous keratopathy. Advantages over other techniques of posterior chamber lens implantation in the absence of capsular support include technical ease, avoidance of iris fixation, and more precise placement of scleral fixation sutures, thus minimizing IOL decentration.

Cellular reactions on heparin surface-modified versus regular PMMA lenses during the first postoperative month. A double-masked and randomized study using specular microphotography

Specular microscopy was used for investigation of cellular reactions on the intraocular lens (IOL) anterior surface of Heparin surface-modified (HSM) versus regular polymethylmethacrylate (PMMA) lenses (Pharmacia types 700C versus 700B, respectively). The double-masked randomized study included 53 patients investigated at 1 and 4 weeks postoperatively. Giant cells were only found on control lenses and more frequently at 4 weeks. Small cells were found on both lens types, but in a higher frequency on the control lenses. The number of small cells decreased during the first 4 weeks on both the control and HSM lenses. However, those control lenses that had giant cells on their surface showed an increase in the number of small cells during the same time. The results of the current study show that HSM lenses give rise to less postoperative inflammatory cellular reactions than regular PMMA lenses.

Experimental intraocular lens implantation in the rabbit eye and in the mouse peritoneal space. Part V: Phagocytosis and nuclear patterns of giant cells observed on the implanted lens surface

The major cellular components on intraocular lenses experimentally implanted in the rabbit eye and in the mouse peritoneal space were examined. They consisted of macrophages and their metamorphosed epithelioid cells with occasional formations of foreign-body giant cells from the fusion of the macrophage-related cells. Lymphocytes, individually and in clusters, were also seen on the lenses implanted in the mouse peritoneal space but rarely on those implanted in the rabbit eye. Macrophages, epithelioid cells, and giant cells exhibited active phagocytosis on the implanted intraocular lenses. These cells phagocytized not only minor foreign particles such as artificially fed latex or carbon colloids but also living cells including erythrocytes, leukocytes, and lymphocytes. The nuclear pattern of the giant cell formation process initially assumed a centrally located nuclear distribution of a foreign-body giant cell type, and then a peripherally located Langhans type distribution when the number of nuclei reached about five in both the mouse peritoneal space and the rabbit eye chamber. Ultra-large giant cells containing a number of nuclei, however, were only observed on lenses implanted in the rabbit eye, demonstrating a difference between the two environments.

Penetrating keratoplasty for pseudophakic bullous keratopathy associated with closed-loop anterior chamber intraocular lenses

Closed-loop anterior chamber intraocular lenses (AC IOLs) are associated with a high incidence of pseudophakic bullous keratopathy (PBK). The prognosis for recovery of vision with penetrating keratoplasty and the exchange of one type of AC IOL for another remains controversial. A total of 40 consecutive patients with closed-loop AC IOLs and varying degrees of PBK underwent penetrating keratoplasty, explanation of the closed-loop AC IOL, and implantation of a flexible tripod AC IOL--all done with a uniform technique. The average follow-up study was 24 months. Average preoperative visual acuity was 20/170 (range, 20/25-hand motions) and average postoperative visual acuity was 20/44 (range, 20/20-no light perception). A total of 23 eyes (57.5%) achieved a visual acuity of 20/40 or better. Eleven eyes (27.5%) had a visual acuity of 20/200 or worse. Persistent cystoid macular edema was the most frequent cause of poor vision postoperatively (4 eyes), followed by age-related macular degeneration (3 eyes) and graft rejection (2 eyes). This is the first series documenting a good visual outcome for at least 2 years after penetrating keratoplasty and exchange of a closed-loop AC IOL for a single type of flexible tripod AC IOL.

Capsular bag distension after endophacoemulsification and posterior chamber intraocular lens implantation

Six cases of capsular bag distension after capsulorhexis, endophacoemulsification, and posterior chamber intraocular lens (IOL) implantation are presented. Five cases had prominent posterior subcapsular cataracts preoperatively. In three cases, the anterior chamber depths were shallower and the apparent refractive errors were more myopic than normal after surgery. All six cases exhibited an apparent early complete sealing of the anterior capsular remnant against the anterior IOL optic. In each case, the capsular bag contained moderate particulate debris and flare while the adjacent vitreous and anterior chambers were clear. I suspect the particles are epithelial cell and cortical debris suspended in a fluid comprising lens epithelial protein, cellular breakdown products, balanced salt solution, and water. Five cases have received no specific treatment. In one case, a neodymium:YAG laser anterior capsulotomy allowed a forward egress of fluid from the distended capsular bag and a return to normal pseudophakic anatomy.

Forces on intraocular lens haptics induced by capsular fibrosis. An experimental study

Electronic dynamometry measurements, performed upon intraocular lens (IOL) haptics of prototype one-piece three-loop silicone lenses, accurately defined the relationships between elastic force and haptic displacement. Lens implantations in the capsular bag of dogs (loop span equal to capsular bag diameter, loops underformed immediately after the operation) were evaluated macrophotographically 5-8 months postoperatively. The highly constant elastic property of silicon rubber permitted quantitative correlation of subsequent in vivo haptic displacement with the resultant force vectors responsible for tissue contraction. The lens optics were well centered in 17 (85%) and slightly offcenter in 3 (15%) of 20 implanted eyes. Of the 60 supporting loops, 28 could be visualized sufficiently well to permit reliable haptic measurement. Of these 28, 20 (71%) were clearly displaced, ranging from 0.45 mm away from to 1.4 mm towards the lens' optic center. These extremes represented resultant vector forces of 0.20 and 1.23 mN respectively. Quantitative vector analysis permits better understanding of IOL-capsular interactions.

Sutured retropupillary posterior chamber intraocular lenses for exchange or secondary implantation. The 12th annual Binkhorst lecture, 1988

The histopathologic findings of four eyes obtained postmortem with iris-sutured posterior chamber intraocular lenses (PC IOLs) are described. These IOLs were implanted as exchange procedures. In most instances, the loops were not situated in the ciliary sulcus but rather were suspended behind the iris and ciliary body. Therefore, the primary mechanism of fixation of iris-sutured PC IOLs appears to be the sutures themselves rather than adherence to the ciliary tissues. This report of four eyes is preliminary, but the pathologic analysis, showing few significant lesions attributable to the IOL, provides a reason for optimism for using this technique. A long-term clinical study comparing the results of sutured PC IOLs with those of anterior chamber IOLs (AC IOLs) used in secondary or exchange implantation, as well as collection and analysis of more pathologic specimens, should provide a more definitive answer as to the preferred procedure.

Penetrating keratoplasty for pseudophakic bullous keratopathy associated with semiflexible, closed-loop anterior chamber intraocular lenses

We performed penetrating keratoplasty on 32 eyes that developed pseudophakic bullous keratopathy associated with closed-loop anterior chamber intraocular lenses. All lenses were exchanged at the time of keratoplasty. Seventeen patients received anterior chamber intraocular lenses and 15 patients had a posterior chamber lens sutured to the iris or sclera. Postoperatively, 13 of 32 eyes (41%) achieved a visual acuity of 20/100 or better, and 27 of 32 eyes (84%) had a clear graft. A high incidence of cystoid macular edema (eight cases), and graft rejection (seven cases) resulted in marked visual loss.

Complications of implanting three-piece C-loop posterior chamber lenses in the anterior chamber

We have examined a total of four eyes in three patients who had undergone implantation of three-piece C-loop posterior chamber intraocular lenses into the anterior chamber. All four eyes exhibited four or more of the following complications: 1) loop encapsulation by peripheral anterior synechiae; 2) recurrent iritis; 3) central loop displacement with corneal endothelial touch; 4) progressive endothelial cell loss and corneal edema; 5) glaucoma; and 6) cystoid macular edema. Intraocular lens removal was required in all four eyes, and penetrating keratoplasty was performed in one. We believe that these complications are attributable to the inherent fallacies of fixating three-piece open-loop lenses in the anterior chamber angle.