Electron-microscopic study of pseudo-exfoliation of the lens capsule

Histopathology of Exfoliation Syndrome

Exfoliation syndrome (XFS) is characterized by light and electron microscopy by age-dependent gradual accumulation of whitish material of largely unknown composition and origin along both the anterior and posterior chambers and widely within the iris stroma. These deposits can be fairly specifically labeled with selected antibodies and lectins. Immunohistochemistry shows that intraocular exfoliation deposits share antigens with the microfibrillar elastic fiber system and several basement membrane components, including carbohydrate epitopes on glycosaminoglycans, proteoglycans, and cell adhesion molecules. The earliest histopathologic manifestation of XFS seems to be the deposition of characteristic fibers in various extraocular and anterior segment tissues, as observed by electron microscopy, and perivascular deposition of material within the iris stroma, which is antigenically typical of that found in classic intraocular exfoliation deposits. These findings precede the clinical diagnosis of XFS and likewise can be detected in the seemingly uninvolved fellow eyes of patients with clinically unilateral XFS. Indeed, histopathologic examination of capsulotomy, iridectomy, and trabeculectomy specimens can lead to a clinically unexpected diagnosis of XFS. Exfoliation fibers are additionally found widely distributed in extraocular connective tissues and visceral organs, but the matrix of these fibers seems to differ from that of intraocular deposits. In addition to this histopathologic discrepancy, both the frequent occurrence of clinically unilateral, histopathologically highly asymmetric exfoliation deposits, and the relationship between the early iris vasculopathy that not infrequently may be observed histopathologically for years before classic widespread exfoliation deposits appear along the anterior and posterior chambers remain to be resolved.

Non-contact in vivo confocal scanning laser microscopy in exfoliation syndrome, exfoliation syndrome suspect and normal eyes

PURPOSE

This study aimed to evaluate the efficacy of non-contact confocal laser microscopy in detecting structural alterations of the cornea, iris and lens in fellow eyes of patients with clinically unilateral exfoliation syndrome (XFS) and XFS suspects.

METHODS

In a prospective observational case series, eyes of 12 patients with clinically unilateral XFS, six XFS suspects and six age-matched controls were divided into four groups. Group A included eyes with clinically visible exfoliation material (XFM) on the pupillary border or anterior lens capsule (n = 12); group B included fellow eyes of clinically unilateral XFS patients without visible XFM (n = 12); group C comprised eyes in XFS suspects with signs of pigment dispersion without visible XFM (n = 10), and group D consisted of control eyes with no evidence of XFM or pigment dispersion (n = 12). The cornea, iris and lens were imaged using a non-contact lens prototype for the Rostock Cornea Module (HRT II). Images were analysed by two observers masked to the clinical findings.

RESULTS

Visible XFM (group A) on the lens capsule was characterized by hyperreflectivity in the granular and central disc areas and hyporeflective spaces in the intermediate zones. Similar hyperreflectivity was noted in four of 12 and one of 10 eyes in groups B and C, respectively, but in none in group D. Corneal endothelial hyperreflective deposits were found in eight of 12, four of 12 and one of 10 eyes in groups A, B and C, respectively, and no eyes in group D.

CONCLUSIONS

This technology permits visualization of XFM and ⁄ or XFMrelated changes in the cornea and lens in the unaffected eyes of patients with clinically unilateral XFS. It may allow early detection of XFS and impact glaucoma screening and clinical surveillance decisions.

Atomic force microscopy-based antibody recognition imaging of proteins in the pathological deposits in pseudoexfoliation syndrome

The phenomenon of protein aggregation is of considerable interest to various disciplines, including the field of medicine. A range of disease pathologies are associated with this phenomenon. One of the ocular diseases hallmarked by protein aggregation is the Pseudoexfoliation (PEX) Syndrome. This condition is characterized by the deposition of insoluble proteinaceous material on the anterior human lens capsule. Genomic and proteomic analyses have revealed an association of specific genetic markers and various proteins, respectively, with PEX syndrome. However, the ultrastructure of the protein aggregates is poorly characterized. This study seeks to build capacity to determine the molecular nature of PEX aggregates on human lens capsules in their native state by AFM-based antibody recognition imaging. Lysyl oxidase-Like 1 (LOXL1), a protein identified as a component of PEX aggregates, is detected by an antibody-modified AFM probe. Topographical AFM images and antibody recognition images are obtained using three AFM-based techniques: TREC, phase and force-volume imaging. LOXL1 is found to be present on the lens capsule surface, and is localized around fibrous protein aggregates. Our evaluation shows that TREC imaging is best suited for human tissue imaging and holds significant potential for imaging of human disease tissues in their native state.

Detecting protein aggregates on untreated human tissue samples by atomic force microscopy recognition imaging

We apply topography and recognition (TREC) imaging to the analysis of whole, untreated human tissue for what we believe to be the first time. Pseudoexfoliation syndrome (PEX), a well-known cause of irreversible blindness worldwide, is characterized by abnormal protein aggregation on the anterior lens capsule of the eye. However, the development of effective therapies has been hampered by a lack of detailed knowledge of the protein constituents in these pathological deposits and their distribution. Using both TREC and immunofluorescence, one of the proteins implicated in the PEX pathology--the apolipoprotein clusterin--was detected, and differences in its distribution pattern on the surface of untreated human lens capsule tissue in both PEX and normal control samples were investigated. Our study shows the potential of TREC imaging for the analysis of whole, untreated human tissue samples.

The ultrastructural changes in the exfoliation syndrome

Exfoliation fibrils have a characteristic ultramicroscopic appearance. They are 20-30 nm thick with 10 nm subunits and may be 800 or 900 nm long. They sometimes have a characteristic banding periodicity of about 50 nm. The fibrils have been located in the lens capsule, zonular threads, iris, ciliary body and trabecular meshwork. Extraocular locations have also been found in conjunctival vessels and retroorbital tissue.

Light microscopy of the exfoliation syndrome

The exfoliation syndrome affects all structures of the ocular anterior segment, as well as the conjunctiva and occasionally, nonocular structures. The exfoliative material has been shown by a series of light microscopic and gross anatomic studies to be only loosely adherent to the anterior lens capsule, zonules and anterior vitreous face, and firmly adherent to the equatorial lens capsule and posterior epithelium of the iris and the nonpigmented ciliary epithelium. Electron microscopy demonstrates that, in these latter regions, exfoliation material consisting of characteristic, cross-banded fibrils embedded in an amorphous matrix, is present both within the epithelial cells and associated with a disorganized, reduplicated basement membrane. These findings suggest that the material arises from the epithelium of the lens, iris and ciliary body, possibly the result of an underlying metabolic disorder. From these areas, the material enters the aqueous humor and later deposits on the anterior lens capsule, zonules, vitreous face, anterior surface of the iris, and trabecular meshwork. Histochemical studies demonstrate the presence of glycosaminoglycans, which may comprise the interfibrillar portion of the exfoliative material. Other studies demonstrate histochemical similarities between exfoliative material and zonules and are supported by recent work suggesting that the exfoliative fibrils are related to the microfibrillar portion of elastin. Although some reports suggest similarities between exfoliative material and amyloid, a majority of histochemical studies do not support this possibility.

Ultrasound biomicroscopy of zonular anatomy in clinically unilateral exfoliation syndrome

PURPOSE

To evaluate the ability of ultrasound biomicroscopy (UBM) to detect abnormalities in the zonular apparatus in unaffected eyes of patients with clinically unilateral exfoliation syndrome (XFS) using a standardized grading system.

METHODS

The affected and unaffected eyes of 17 patients with clinically unilateral XFS and 17 eyes of 17 control subjects underwent UBM. Radial sections detailing the lens and zonules at 12:00, 1:30, 3:00, 4:30, 6:00, 7:30, 9:00 and 10:30 clock hours were obtained. The images were graded by a masked, experienced UBM observer using a standardized scoring system based on the zonular appearance (0, none; 1 and 2, uneven or disrupted zonules with or without patchy deposits; 3, diffuse granulation, thick zonules or both; 4, total zonular disruption). Affected meridians were compared by the Friedman test, while distributions of unaffected and affected eyes were compared using the Student t-test.

RESULTS

In the control group, 15/17 eyes showed normal zonules; the remaining two eyes showed grade 1 changes in some meridians. The mean grade score was 0.33 [standard deviation (SD) 0.84]. Eyes with XFS had a higher score than control eyes, with a mean score of 14.35 (SD 7.14, P < 0.001, Student t-test). In clinically unaffected fellow eyes, the mean score was 10.53 (SD 7.44), and was less than that of XFS eyes (P = 0.008, Student t-test). Twelve XFS eyes (71%) and six unaffected fellow eyes (35%) had grade 3 or 4 in at least one meridian (P = 0.07, Friedman test).

CONCLUSION

Bilateral zonular involvement is present in subjects with clinically unilateral XFS. These zonular changes may be extensive in fellow eyes without clinically evident exfoliation material. UBM assessment of zonular status in fellow eyes prior to cataract extraction may aid in surgical planning.

Ultrasound biomicroscopic assessment of zonular appearance in exfoliation syndrome

PURPOSE

To assess zonular appearance using biomicroscopy (UBM) in exfoliation syndrome (XFS).

METHODS

Normal eyes and eyes with XFS were enrolled in this prospective, consecutive, comparative cohort study. Following pupillary dilation, XFS patients were classified into three clinical stages (early, moderate or severe) by a single examiner (R.R.). Cross-sectional zonular UBM images were obtained circumferentially at eight evenly spaced locations. Five experienced observers evaluated the images using a standardized scoring system based on the zonular appearance (0, none; 1, early; 2, moderate; 3, severe). The extent of zonular involvement on UBM based on UBM score of all observers was correlated with the clinical stage of XFS using a five-stage classification.

RESULTS

We enrolled 44 eyes (44 patients), 11 normal and 33 with XFS (10 early, 10 moderate and 13 severe) [mean age 69.4 +/- 9.9 (SD) years; range 50-87 years]. UBM scores of all observers were significantly different between the normal/early and moderate/severe groups (P < 0.001, t-test). With discriminant analysis, the predicted XFS stage showed good agreement with the clinical staging [all kappa > 0.61, area under receiver operating characteristic (ROC) curve > 0.86].

CONCLUSION

UBM can detect zonular involvement in XFS and may be useful in preoperative planning. This may be important in eyes with posterior synechiae in which a diagnosis and the severity of XFS cannot be determined on slit-lamp examination.

Zonular fibers, multimolecular composition as related to function (elasticity) and pathology

Zonular fibers (ZF) play an important role in accommodation. With the rapid increase over the last decade of the oldest part of the population in industrialized countries, age-dependent loss of accommodation became an increasingly important problem. It appeared therefore interesting to review old and recent literature on ZF, their composition, structure and pathological alterations. By comparing former and recent reports it appeared to us, that several previous reports were not sufficiently taken in consideration for the understanding of the rheological properties of ZF. Elastin and proteoglycans-glycosaminoglycans were reported previously as constituents of ZF. Their presence besides fibrillin, the major constituent, helps to explain the rheological properties of these fibers, and especially their elasticity and its age- and pathology-dependent decline. Our review points also to some of the major problems, which remain to be addressed by future experiments.

Characterizing pseudoexfoliation syndrome through the use of ultrasound biomicroscopy

PURPOSE

To determine the clinical utility of ultrasound biomicroscopy (UBM) in diagnosis of pseudoexfoliation (PEX) syndrome by characterizing the lens capsule and zonules before cataract surgery.

SETTING

Veterans Administration Hospital, East Orange, and University of Medicine & Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey, USA.

METHODS

Ultrasound biomicroscopy was performed on 10 patients clinically diagnosed with PEX syndrome. The clinical diagnosis was made by the presence of fibrillin deposits on the anterior lens capsule, lack of pigment at the pupillary ruff, and poor pharmacologic dilation. Five persons without PEX were used as controls. The thickness of the anterior lens capsule was measured in 5 locations in each eye: centrally and in the peripheral lens capsule superiorly, inferiorly, nasally, and temporally. Four measurements were taken from the zonule at the thickest point on each fiber. The UBM also found the presence or absence of nodular deposits on the zonules.

RESULTS

The anterior and peripheral lens capsule in patients with PEX was thicker than that in the control group. Additionally, patients with PEX had thicker zonules than the control group and had nodular deposits present; the control group had no deposits. These differences were all significant with a 99% confidence interval.

CONCLUSIONS

A thicker anterior lens capsule and lens zonule nodules were associated with PEX. These abnormalities can be visualized with the UBM to confirm the diagnosis of PEX and identify patients at risk for operative complications.

Exfoliation syndrome

Exfoliation syndrome (XFS) is an age-related disease in which abnormal fibrillar extracellular material is produced and accumulates in many ocular tissues. Its ocular manifestations involve all of the structures of the anterior segment, as well as conjunctiva and orbital structures. Glaucoma occurs more commonly in eyes with XFS than in those without it; in fact, XFS has recently been recognized as the most common identifiable cause of glaucoma. Patients with XFS are also predisposed to develop angle-closure glaucoma, and glaucoma in XFS has a more serious clinical course and worse prognosis than primary open-angle glaucoma. There is increasing evidence for an etiological association of XFS with cataract formation, and possibly with retinal vein occlusion. XFS is now suspected to be a systemic disorder and has been associated preliminarily with transient ischemic attacks, stroke, systemic hypertension, and myocardial infarction. Further ramifications await discovery. Deposits of white material on the anterior lens surface are the most consistent and important diagnostic feature of XFS. The classic pattern consists of three distinct zones that become visible when the pupil is fully dilated. Whereas the classic picture of manifest XFS has been often described, the early stages of beginning exfoliation have not been well defined. Next to the lens, exfoliation material is most prominent at the pupillary border. Pigment loss from the iris sphincter region and its deposition on anterior chamber structures is a hallmark of XFS. Despite extensive research, the exact chemical composition of exfoliation material (XFM) remains unknown. An overproduction and abnormal metabolism of glycosaminoglycans have been suggested as one of the key changes in XFS. The protein components of XFM include both noncollagenous basement membrane components and epitopes of the elastic fiber system such as fibrillium. Regardless of etiology, typical exfoliation fibers have been demonstrated electron microscopically in close association with the pre-equatorial lens epithelium, the nonpigmented ciliary epithelium, the iris pigment epithelium, the corneal endothelium, the trabecular endothelium, and with almost all cell types of the iris stroma, such as fibrocytes, melanocytes, vascular endothelial cells, pericytes, and smooth muscle cells. The presence of XFS should alert the physician to the increased risks of intraocular surgery, most commonly zonular dehiscence, capsular rupture, and vitreous loss during cataract extraction. Heightened awareness of this condition and its associated clinical signs are important in the detection and management of glaucoma, and preoperative determination of those patients at increased risk for surgical complications.

Intraocular lens tilt and decentration after implantation in eyes with glaucoma

PURPOSE

To evaluate the extent of intraocular lens (IOL) tilt and decentration after implantation in eyes with glaucoma.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

Fifty-two eyes of 52 patients with glaucoma and 52 control eyes from 52 age-matched patients had phacoemulsification with IOL implantation. Twenty-nine eyes had closed-angle glaucoma (CAG), and the other 23 eyes had open-angle glaucoma (OAG). The extent of IOL tilt and decentration was measured using Scheimpflug videophotography 1 week and 1, 3, 6, 9, and 12 months postoperatively.

RESULTS

The mean tilt angle in the glaucoma group was significantly greater than in the control group throughout the follow-up. Mean decentration length was also greater in the glaucoma than in the control group, but the difference was not significant. The incidence of eyes showing a marked tilt (greater than 5 degrees) or decentration (greater than 0.5 mm) was higher in the glaucoma than in the control group. The mean tilt angle and the incidence of eyes showing a marked tilt or decentration in the CAG group were significantly greater than in the control group.

CONCLUSION

Intraocular lens tilt was more extensive in the eyes with glaucoma, especially in those with CAG, than in normal eyes. Decentration was also greater in the glaucoma groups than in the control group, although the differences were not significant.

Anterior capsule contraction and intraocular lens dislocation in eyes with pseudoexfoliation syndrome

AIMS

To examine the extent of anterior capsule contraction as well as intraocular lens (IOL) decentration and tilt following implant surgery in eyes with pseudoexfoliation syndrome (PE).

METHODS

53 eyes from 53 patients with PE and 53 control eyes from 53 age matched patients, undergoing phacoemulsification and implant surgery, were recruited. The anterior capsule opening area and the amounts of IOL decentration and tilt after undergoing continuous curvilinear capsulorhexis were measured using the Scheimpflug videophotography system at 1 week and 1, 3, 6, 9, and 12 months postoperatively.

RESULTS

The mean area of the anterior capsule opening in the PE group was significantly smaller than that in the control group at 1 month postoperatively and later. The percentage reductions in the PE group were approximately 25%, while they were less than 10% in the control group. The degree of IOL tilt was also larger in the PE group than in the control group. Five eyes (9.4%) in the PE group underwent a neodymium: YAG laser anterior capsulotomy, but none in the control group underwent a capsulotomy.

CONCLUSIONS

The contraction of the anterior capsule opening was more extensive in the PE eyes than in the control eyes, thus resulting in a high Nd:YAG laser anterior capsulotomy rate. The IOL tilt was also greater in the PE eyes than in the control eyes.

Distribution and characterization of proteoglycans associated with exfoliation material

PURPOSE

To examine the distribution of proteoglycans in the exfoliation materials in order to investigate the nature of the materials.

METHODS

The anterior parts of two eyes with exfoliation syndrome were examined by electron microscopy after staining with cupromeronic blue (cmb). Some specimens were treated with enzymes and/or nitrous acid prior to staining. The effects of the enzymes were evaluated statistically by counting the density of the cmb-positive filaments in the exfoliation materials, using a computer. One eye with exfoliation syndrome stained with alcian blue was observed with light microscopy.

RESULTS

Exfoliation materials were observed along the epithelial cells of the iris and ciliary body, and in the trabecular meshwork and zonules. In tissue specimens treated with cmb, electron-dense filaments were seen associated with the exfoliation materials. Microfibrils in the trabecular meshwork and iris, and zonular fibrils themselves were free of any filament staining, while the exfoliation materials located closely to the fibrils contained the electron-dense filaments. In the tissue specimens treated with chondroitinase AC, chondroitinase B, chondroitinase ABC or nitrous acid before cmb staining, the amount of the filament associated with exfoliation materials decreased in comparison to the controls. Digestion with keratinase did not demonstrate any significant changes in staining. A combination treatment with chondroitinase ABC and nitrous acid eliminated almost all filaments associated with the exfoliation materials. In the eye stained with alcian blue, the zonules that did not stain for the dye demonstrated an accumulation of exfoliation materials that stained strongly for alcian blue.

CONCLUSIONS

Exfoliation materials contain chondroitin sulfate, dermatan sulfate, heparan sulfate proteoglycans. Depositions of proteoglycans on the microfibrils may be closely associated with the formation of exfoliation materials.

Prevalence and surgical complications of pseudoexfoliation syndrome in Portuguese patients with senile cataract

PURPOSE

To determine the prevalence and surgical complications of pseudoexfoliation syndrome (PES) in a Portuguese population of patients with senile cataract.

SETTING

Department of Ophthalmology, Coimbra University Hospitals, Coimbra, Portugal.

METHODS

In a prospective study, 183 consecutive patients with senile cataract referred to the Implant and Refractive Surgery Section of the Department of Ophthalmology were examined for PES. To determine the occurrence of intraoperative and postoperative complication of extracapsular extraction with posterior chamber intraocular lens implantation in patients with PES, two groups of similar age were compared: one with PES (n = 31) and a control group without PES (n = 31).

RESULTS

The prevalence of PES in the 183 Portuguese patients with senile cataract was 23.5%. There was statistically significant difference between the two groups in the presence of phacodonesis (P < .05), insufficient intraoperative mydriasis (P < .001), need to perform sphincterotomies to facilitate nucleus expression (P < .01), and formation of pupillary fibrin membranes in the postoperative period (P < .01). These complication were more frequent in the PES group. Zonular breaks also occurred more often in patients with PES, although this was not statistically significant.

CONCLUSIONS

Pseudoexfoliation syndrome was a common condition in patients with senile cataract having surgery in Portugal. Inadequate mydriasis was the major intraoperative difficulty; a pupil enlargement procedure should be performed in these cases. In the first days postoperatively, therapy with topical, subconjunctival, and systemic corticosteroids is recommended to reduce the inflammatory reaction in the anterior chamber.

A histopathologic study of zonular instability in pseudoexfoliation syndrome

A weak zonular apparatus has been postulated to account for the high incidence of phacodonesis, lens dislocation, and vitreous complications during extracapsular cataract surgery in eyes with pseudoexfoliation syndrome. To clarify and localize the cause of zonular weakness, we examined 11 eyes with pseudoexfoliation syndrome by using scanning and transmission electron microscopy. The production of pseudoexfoliation material by both the nonpigmented ciliary epithelium and the pre-equatorial lens epithelium resulted in typical alterations of the zonules at three levels. (1) At their origin and anchorage in the ciliary body, the zonular bundles were separated from the disrupted basement membrane of the nonpigmented epithelium by intercalating pseudoexfoliation fibers. (2) In the pars plicata of the ciliary body, pseudoexfoliation material infiltrated the zonular bundles passing alongside the ciliary processes leading to zonular rupture. (3) At their attachment to the anterior lens capsule, the zonular lamella was focally lifted and subsequently ruptured by pseudoexfoliation masses erupting through the capsular surface. The immunohistochemical demonstration of lysosomal enzymes within pseudoexfoliation aggregates indicates that proteolytic mechanisms facilitate zonular disintegration. Ophthalmologists treating eyes with pseudoexfoliation syndrome should be aware of these alterations.

Capsule contraction syndrome

Capsule contraction syndrome is an exaggerated reduction in anterior capsulectomy and capsular bag diameter after extracapsular cataract surgery. While rarely seen with can-opener-style capsulectomies with anterior radial capsular tears, it is relatively frequent with capsulorhexis. It is particularly common in patients with pseudoexfoliation and in eyes with a history of moderately severe uveitis. Its effects, which include extreme reduction in the capsulectomy opening, malposition of the opening, reduction in equatorial capsular diameter, and displacement of the IOL, seem more exaggerated in small capsulorhexis openings and in the older patient. Neodymium: YAG laser radial anterior relaxing capsulotomies done within three weeks of cataract surgery reduce the sphincter effect of the contraction and lessen the chronic zonular-traction-related complications of the condition, which may include spontaneous IOL dislocation and retinal detachment.

Pseudoexfoliation syndrome as a risk factor for acute ciliary block angle closure glaucoma

Two patients presented with unilateral ciliary block angle closure glaucoma and bilateral pseudoexfoliation (PSX) syndrome and were treated successfully with posterior sclerotomy (one case), extracapsular cataract extraction and posterior chamber lens implantation. None of the eyes had undergone previous ocular surgery except Nd: YAG-laser iridotomy. Axial lengths as measured with A-scan ultrasonography were 22.48 mm and 24.30 mm. During follow-up of 5 and 12 months, intraocular pressure was well controlled without antiglaucoma medication in both patients. We suspect that the well-known changes of the zonula origin at the ciliary epithelium in PSX syndrome lead to anterior subluxation of the lens with consecutive ciliary block angle closure glaucoma. Ciliary block angle closure glaucoma seems to be another serious complication in PSX syndrome. Therefore, miotics should probably be used with care in PSX eyes with signs of zonular alterations because they may trigger this mechanism.

Exfoliation syndrome and the effect of phenylephrine and pilocarpine on pupil size

The horizontal diameter of the pupil was measured on 20 eyes with exfoliation syndrome and 20 control eyes before and after the instillation of 10% phenylephrine and 4% pilocarpine eye drops. Pupil dilation induced by topical application of the alpha 1 adrenoceptor agonist phenylephrine was significantly smaller in eyes with exfoliation syndrome compared to controls. The cholinergic agonist pilocarpine decreased pupil diameter and this effect was significantly less in cases with exfoliation syndrome. We conclude from these data that the pharmacological response to both adrenergic and cholinergic stimulation is weaker in eyes with exfoliation syndrome compared to controls.

Quantitative assessment of aqueous flare and aqueous 'cells' in pseudoexfoliation syndrome

We used the laser flare-cell meter to measure aqueous flare and aqueous 'cells' in 38 eyes of 38 patients with pseudoexfoliation, in 36 normal control eyes of 36 subjects, and in 19 eyes of 19 patients with chronic open-angle glaucoma unrelated to pseudoexfoliation. In pseudoexfoliation eyes, both aqueous flare (0.61 +/- 0.55 mg/ml human albumin equivalent) and aqueous 'cells' (mean 10.70, range 0-50.6 cells/0.075 mm3) were significantly higher than in the normal control group (flare 0.15 +/- 0.06 mg/ml, 'cells' 0.43, range 0-2, P less than 0.0001) and in the glaucoma group without pseudoexfoliation (flare 0.19 +/- 0.08 mg/ml, 'cells' 0.80, range 0-2.4, P less than 0.0001 and P less than 0.005). No significant difference could be found between the flare and cell counts of normal eyes and glaucoma eyes without pseudoexfoliation (P greater than 0.09, P greater than 0.05) and between PSX eyes with (18 eyes) and without (20 eyes) open-angle glaucoma (P greater than 0.99, P greater than 0.4). Our findings indicate that the blood-aqueous barrier is impaired in eyes with pseudoexfoliation, and that the laser flare-cell meter may be a useful tool to quantify these changes. These alterations of the blood-aqueous barrier need to be considered in medical therapy and intraocular surgery.

Occurrence of pseudoexfoliative material in parabulbar structures in pseudoexfoliation syndrome

The blind and painful left eye of a 88-year-old woman was enucleated and examined by light and transmission electron microscopy. Three years earlier, after unilateral pseudoexfoliation syndrome with advanced open angle glaucoma of the left eye had been diagnosed, argon laser trabeculoplasty and pars plicata diathermy were performed. Light microscopy showed deposits of typical pseudoexfoliative material in the anterior segment and endothelialization of the chamber angle. By transmission electron microscopy we demonstrated pseudoexfoliative fibers not only at the typical intraocular locations and in the bulbar conjunctiva but also ultrastructurally identical material in hitherto not described extraocular locations such as extraocular rectus and oblique muscles, vortex veins and the optic nerve sheaths. Ultrastructurally, the fibers showed all the characteristic features of pseudoexfoliative material. Our findings are another strong indication that pseudoexfoliation syndrome is not a purely intraocular disorder but represents a more widespread disease.

Glycoconjugates in exfoliation syndrome. A lectin histochemical study of the ciliary body and lens

The binding of ten biotin-coupled lectins with different carbohydrate specificities to exfoliative material and neighbouring tissues was studied in 16 formalin-fixed and paraffin-embedded human eyes. Eight of the eyes were exfoliation positive while the rest were exfoliation negative. Exfoliative material reacted intensely with Lens culinaris (LCA), Canavalia ensiformis (ConA) and Ricinus communis (RCA-I) agglutinins. Positive reaction was also seen with wheat germ (WGA), peanut (PNA) and soybean (SBA) agglutinins. The superficial zonular lamella, zonular fibers and the non-pigmented epithelium of the ciliary body had a rather similar lectin-binding profile to exfoliative material. The lens capsule was essentially unreactive with all the lectins used. The lens epithelium reacted faintly with ConA, LCA, WGA and RCA-I. Pre-treatment with neuraminidase to remove sialic acid resulted in increased binding of PNA and SBA to exfoliative material, zonular fibers and the zonular lamella, and in decreased binding of WGA to the non-pigmented epithelium of the ciliary body, zonular fibers and the zonular lamella. The results indicate that alpha-mannosyl, beta-galactosyl, N-acetyl-D-glucosaminyl and N-acetylneuraminic acid residues are present in glycoconjugates of exfoliative material and neighbouring tissues.

Risk factors for intraoperative complications in 1000 extracapsular cataract cases

A prospective study of the risk factors in extracapsular surgery was carried out between October 1984 and April 1986. One thousand extracapsular cataract extractions were performed by seven physicians. Decreasing pupil size was the only statistically significant risk factor for vitreous loss (P = 0.0002). Zonular breaks occurred more commonly with pseudoexfoliation syndrome (PX) (P less than 0.0001), with decreasing pupil size (P less than 0.0001), and with one surgeon who used the Simcoe aspirating needle (Storz) exclusively (P = 0.0001). It is acknowledged that it is very difficult to standardize what constitutes a small zonular break; hence, the increase in zonular breaks recorded by this surgeon may have been due only to his using less stringent criteria than the others. Capsule breaks had no significant risk factors at the 0.01 level. High myopia, advanced cataract, glaucoma, advanced age, and diabetes mellitus were not found to be risk factors for vitreous loss, zonular breaks, or capsular breaks.

Ultrastructural observations on (pseudo-) exfoliation of the lens capsule: a re-examination of the involvement of the lens epithelium

One lens each from 2 separate patients suffering from pseudoexfoliation and one lens from a normal eye were examined ultrastructurally. The normal lens capsule was internally lamellar in places and externally of a somewhat reduced electron density but otherwise of a homogeneous appearance and free of inclusions. Observations on the abnormal lenses revealed an electron dense and mainly granular but sometimes fibrillar material along the surface of the peripheral one-third of the capsule. Material of similar ultrastructural appearance was also found deeper in the capsule and in the immediately underlying epithelium. Since the capsule close to the pole of the lens was completely free of these abnormal inclusions and the underlying epithelium also lacked this material, it is concluded that the lens epithelium is a source of the surface debris in pseudoexfoliation. These findings therefore support previous authors who proposed a lenticular involvement in this disease. The present study does, however, not rule out the possibility of a uveal contribution of abnormal material but disputes its exclusive involvement in this disease, as has previously been postulated. Build-up of exfoliated material close to the capsular surface caused an apparent peeling of the lens capsule. It is therefore concluded that the anomalous lenses suffered from a true exfoliative process that may be more correctly termed 'exfoliation of the lens capsule.'

Lysosomal enzymes in ocular tissues and diseases

Lysosomal enzymes are distributed widely in various ocular tissues. Among these tissues, the uvea and retina show the higher enzyme activities of acid phosphates, beta-blucuronidase, alpha-fucosidase, alpha-mannosidase, arylsulfatase, cathepsin D, cathepsin B and others. The particular role of lysosomal enzymes in the pathogenic processes of ocular diseases such as storage disease, uveitis, retinal degeneration, retinal detachment, corneal dystrophy and glaucoma is strongly suggested. The enzymes also have additional importance in ocular physiopathology.

Identification of a basement membrane proteoglycan in exfoliation material

We have used the indirect immunperoxidase technique to examine the exfoliation syndrome and can demonstrate that the fibrils so typically found in this disease certainly contain basement membrane proteoglycans. This finding is interesting for two reasons: 1. For the first time, an electron-microscopical technique is described that is able to identify one protein component of the exfoliation material. 2. The fact that the basement membrane proteoglycans are present in the exfoliation material supports the hypothesis that this disease is caused by a disturbance in the biosynthesis of the basement membrane.

Acid phosphatase in eyes with pseudoexfoliation

We studied the activity of acid phosphatase in the anterior segment of the eye with pseudoexfoliation histochemically and biochemically. Light and electron microscopic histochemistry revealed lead precipitates indicating acid phosphatase activity in pseudoexfoliative materials. Biochemical assay for acid phosphatase was significantly higher in the aqueous humor of eyes with pseudoexfoliation than in that of cataractous eyes without pseudoexfoliation.