Morphology of iris vasculopathy in exfoliation glaucoma

Optic nerve head vessel density in patients with pseudoexfoliation syndrome/glaucoma: a systematic review and meta-analysis

PURPOSE

Exfoliative material has been shown to accumulate in ocular and systemic tissues. We aimed to perform a systematic review and meta-analysis of the current literature evaluating optic nerve head vessel density (VD) using optical coherence tomography angiography (OCTA) in patients with XFS and XFG.

METHODS

Studies were retrieved from PubMed, Scopus, and Web of Science databases. Studies comparing patients with XFS and/or XFG patients to healthy controls, using the optic nerve head-centred 4.5 × 4.5 mm square OCTA scan protocol were included. Pooled results are presented as standardised mean differences with 95% confidence intervals (CI). Meta-regression analysis was performed between mean difference in circumpapillary VD between XFG and controls and mean pRNFL thickness in patients with XFG.

RESULTS

Fifteen studies with 1475 eyes were included in this review. Whole image VD and circumpapillary VD (cpVD) were significantly decreased in patients with XFS [-0.78(95% Cl: -1.08, -0.47); [-0.55(95% Cl: -0.80, -0.30); respectively] and XFG [-1.85(95% CI: -2.33, -1.36); -1.84 (95% CI: -2.30, -1.39); respectively] compared to healthy controls. Furthermore, pRNFL thickness decreased in patients with XFS [-0.55(95% Cl: -0.72, -0.35)] and XFG [-1.78(95% Cl: -2.21, -1.36)] compared to healthy controls. Meta-regression showed that pRNFL thickness decreased with increasing mean cpVD difference in XFG patients compared to healthy controls.

CONCLUSIONS

OCTA provides non-invasive, objective and reproducible assessment of peripapillary VD and is important for the detection of vasculopathy in patients with XFS or XFG. This study provides strong evidence for decreased cpVD in the eyes of patients with XFS and XFG.

The depigmentation degree of iris pigment epithelium in pseudoexfoliation syndrome

BACKGROUND

To compare the optical density of iris pigment epithelium (OD_IPE) and iris stromal thickness (IST) measurements in patients having pseudoexfoliation syndrome (PXS) and age-gender matched participants.

METHODS

This is a cross-sectional study. Patients with PXS were enrolled in the study group. Age and gender-matched healthy subjects with no evidence of PXS were recruited as controls. After a comprehensive ophthalmological evaluation, the anterior segment images were acquired using anterior segment spectral-domain optical coherence tomography (AS SD-OCT). The acquired pictures were further analyzed using the ImageJ program. Two investigators measured the OD_IPE and the IST of the subjects, and the repeatability and reproducibility were checked. SPSS program was used for statistical analysis.

RESULTS

The PXS group was comprised of twenty-two eyes (n = 22 patients), and the control group contained twenty-six eyes of 26 age and gender-matched healthy subjects. The mean temporal OD_IPE of the study group was found to be decreased significantly in comparison to the mean temporal OD_IPE of the control eye (p = 0.018). Both the mean nasal (N) and temporal (T) ISTs of the PEX eyes were thinner than the control eyes (p = 0.006 and p = 0.002, respectively). The mean baseline IOP was found to significantly negatively correlate with the OD_IPE in the PEX group at both N and T sides (r = -0.531, p = 0.011 and r = -0.685, p < 0.001, respectively).

CONCLUSION

The pupillary margin IPE was found more depigmented, and the mean N and T IST were significantly thinner in the PEX group by comparison with the age-gender matched healthy controls. The mean baseline IOP was negatively correlated with the pupillary margin's IPE pigmentation degree in patients with PXS.

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.

A cohort study of duplex Doppler examinations of the carotid artery in primary open angle glaucoma

Objectives

To explore the possibility of pathological change in the common carotid artery at the bifurcation and in the internal carotid artery beyond the bifurcation which could contribute to a reduced diastolic pressure as observed in primary open angle glaucoma.

Design

Duplex ultrasonic examinations of carotid bifurcations were conducted on 80 patients. Carotid artery defects were allocated into three types: no demonstrable flow defects, internal carotid artery abnormalities and disease in the carotid bulb.

Setting

Bristol Royal Infirmary Vascular Laboratory.

Participants

Eighty patients (mean age 69.6 years) providing a total of 160 sides to the analysis.

Main outcome measures

An estimated central retinal artery pressure, intraocular pressure and field loss were recorded for each side measured.

Results

Doppler investigations revealed significant levels of pathological change in the internal carotid distinct from changes at the carotid bulb. The disease revealed in the internal carotid artery was significantly associated with intraocular pressure (p = 0.032), with an effect small to medium in magnitude. The Q2 measure, derived from mean arterial pressure and intraocular pressure, was also substantively associated with disease in the internal carotid artery. Both intraocular pressure and the Q2 measure effectively discriminated between groups, with field loss providing rather less discriminating capability. There was a strong trend towards a higher intraocular pressures and a greater visual field loss with internal carotid artery disease.

Conclusions

Pathological changes in the extra cranial carotid artery in primary open angle glaucoma exceed those in the arteries classified as normal. The presence of disease specifically in the internal carotid artery emphasised the need for a mechanism for the evaluation of the internal carotid apart from the carotid bulb. A basis for clarifying the presence of an ischaemic zone is proposed.

Matrix metalloproteinases and their tissue inhibitors after selective laser trabeculoplasty in pseudoexfoliative secondary glaucoma

BACKGROUND

The aim of this study was to assess changes in metalloproteinases (MMP-2) and tissue inhibitor of metalloproteinases (TIMP-2) following selective laser trabeculoplasty (SLT) in patients with pseudoexfoliative glaucoma (PEXG).

METHODS

We enrolled 15 patients with PEXG and cataracts (PEXG-C group) and good intraocular pressure (IOP) controlled with beta-blockers and dorzolamide eye drops who were treated by cataract phacoemulsification and 15 patients with pseudoexfoliative glaucoma (PEXG-SLT group). The PEXG-SLT patients underwent a trabeculectomy for uncontrolled IOP in the eye that showed increased IOP despite the maximum drug treatment with beta-blockers and dorzolamide eye drops and after ineffective selective laser trabeculoplasty (SLT). The control group consisted of 15 subjects with cataracts. Aqueous humor was aspirated during surgery from patients with PEXG-C, PEXG-SLT and from matched control patients with cataracts during cataract surgery or trabeculectomy. The concentrations of MMP-2 and TIMP-2 in the aqueous humor were assessed with commercially available ELISA kits.

RESULTS

In PEXG-SLT group in the first 10 days after SLT treatment a significant reduction in IOP was observed: 25.8 +/- 1.9 vs 18.1.0 +/- 1.4 mm/Hg (p < 0.001), but after a mean time of 31.5 +/- 7.6 days IOP increased and returned to pretreatment levels: 25.4 +/- 1.6 mm/Hg (p < 0.591). Therefore a trabeculectomy was considered necessary.The MMP-2 in PEXG-C was 57.77 +/- 9.25 microg/ml and in PEXG-SLT was 58.52 +/- 9.66 microg/ml (p < 0.066). TIMP-2 was 105.19 +/- 28.53 microg/ml in PEXG-C and 105.96 +/- 27.65 microg/ml in PEXG-SLT (p < 0.202). The MMP-2/TIMP-2 ratio in the normal subjects was 1.11 +/- 0.44. This ratio increase to 1.88 +/- 0.65 in PEXG-C (p < 0.001) and to 1.87 +/- 0.64 in PEXG-SLT (p < 0.001). There was no statistically significant difference between the PEXG-C and PEXG-SLT ratios (p < 0.671).

CONCLUSION

This case series suggest that IOP elevation after SLT can be a serious adverse event in some PEXG patients. The IOP increase in these cases would be correlated to the failure to decrease the TIMP-2/MMP-2 ratio.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN79745214.

Cerebral haemodynamics in patients with pseudoexfoliation glaucoma

PURPOSE

To evaluate the cerebral haemodynamics in patients with pseudoexfoliation glaucoma.

METHODS

A total of 19 consecutive patients with pseudoexfoliation glaucoma and 19 age- and sex-matched healthy volunteers were recruited in a prospective comparative study. The affected eye in patients with unilateral glaucoma and the eye with more advanced lesions in patients with bilateral glaucoma were included in the study, and the ipsilateral middle cerebral arteries (MCA) were evaluated. While in the controls, the study eye and the ipsilateral MCA were chosen randomly. Measurements included systemic arterial pressure, heart rate, intraocular pressure (IOP), and transcranial colour Doppler parameters, including peak systolic velocity (PSV), end-diastolic velocity (EDV), time-averaged maximum velocity (TAMAX), resistivity index (RI), and pulsatility index (PI).

RESULTS

The mean PSV, EDV, and TAMAX were significantly lower in the patients with pseudoexfoliation glaucoma than in healthy controls (P<0.001, <0.001 and <0.001, respectively). Additionally, patients with pseudoexfoliation glaucoma had significantly higher PI and RI than healthy controls (P=0.001 and 0.04, respectively). Systolic and diastolic blood pressures (P=0.19 and 0.91, respectively) and heart rate (P=0.06) were not different between the groups. The mean IOP were significantly higher in the glaucoma patients compared with the controls (P<0.001).

CONCLUSION

This study suggests that pseudoexfoliation glaucoma is associated with a reduction in the blood flow velocity and elevation in the resistance of the MCA.

Study of conjunctival goblet cell morphology and tear film stability in pseudoexfoliation syndrome

BACKGROUND

Tear secretion and tear film stability seem to be influenced by pseudoexfoliation syndrome (PEX). Histopathological evaluation of conjunctival goblet cells in PEX patients might explain the influence on tear film stability.

METHODS

In a prospective, cross-sectional study, 40 eyes of 40 patients with PEX (study group) had measurement of Schirmer test with anesthesia and break-up time prior to cataract surgery. At the end of an uneventful operation, a 1 x 1.5 mm sample of conjunctival tissue was obtained and light and electron microscopy were performed. Results were compared with a control group. Histology evaluation was masked. Primary outcome measures included Schirmer test with anesthesia, break-up time, goblet cell density and morphological character of conjunctiva and conjunctival goblet cells.

RESULTS

Both Schirmer test and break-up time values were significantly lower (P= 0.01 and P= 0.001) in the PEX patients (mean 10.6 mm and 8.6 s respectively) than in the control group (13.4 mm and 12.3 s respectively). The number of goblet cells in patients with PEX compared with the control group showed no statistically significant difference (P= 0.66). Use of trichrome stain revealed significant differences in the staining properties of goblet cells between patients with PEX and controls. On electron microscopy, typical pseudoexfoliation filaments were found in the connective tissue of conjunctiva of PEX patients. Remarkable changes of mucin pockets in the study group were also noticed; they had extremely irregular distribution, various forms of size and appearance and even complete collapse.

CONCLUSION

Pseudoexfoliation seems to alter basic features of goblet cell morphology, thus affecting tear film stability. Further studies are necessary to determine the exact mechanism.

Pseudoexfoliation syndrome: pathological manifestations of relevance to intraocular surgery

Pseudoexfoliation syndrome (PEX) is a common ocular condition often associated with the need for intraocular surgery. Although results of cataract and glaucoma filtering surgery in eyes with PEX in the early stages of the disease may be comparable to those in eyes without PEX, in the later stages morbidity is significantly increased due to periocular surgical complications and the outcome is worse. Surgical and postoperative difficulties are often multifactorial and are directly related to the pathological changes of PEX on intraocular structures. Recent years have seen a large increase in the understanding of the effects of PEX on the various ocular tissues. Although the visible areas of the anterior capsule are most obviously involved, this is only a small part of the picture and of least significance. Biomicroscopically invisible changes of the zonules and their attachments are of greatest consequence. There is also distinct, often active, involvement of almost all tissues of the anterior segment of the eye, many of which have important implications for the anterior segment surgeon including iridopathy, iris vasculopathy (including persistent breakdown of the blood-aqueous barrier and anterior segment hypoxia), ciliary body involvement and keratopathy. Trabecular dysfunction is evident by the deposition of PEX material derived from both in situ and extra-trabecular production as well as protein and melanin deposition. These changes should be kept in mind by all intraocular surgeons as a source of potential difficulties in the perioperative period. Additionally, in light of these changes, patients need to be given realistic expectations regarding the increased risk of complications and more prolonged expected recovery time. In this short review, current reports relating to PEX pathological changes of practical interest to the intraocular surgeon are summarized.

8-Isoprostaglandin F2a and ascorbic acid concentration in the aqueous humour of patients with exfoliation syndrome

BACKGROUND/AIMS

The authors investigated the concentrations of 8-isoprostaglandin F(2a), a marker of oxidative stress in vivo, and ascorbic acid, a protectant against oxidative damage, in the aqueous humour of patients with exfoliation syndrome (XFS) and cataract and compared the results with those in age matched patients with cataract, but without XFS, to determine whether XFS is associated with increased oxidative stress.

METHODS

Aqueous humour was aspirated at the beginning of phacoemulsification cataract surgery from 27 eyes of 27 cataract patients with XFS and 27 eyes of 27 age matched cataract patients without XFS. 8-Isoprostaglandin F(2a)concentration in the aqueous was determined with a commercial immunoassay; ascorbic acid concentration was measured with a microplate assay method.

RESULTS

The mean concentration of 8-isoprostaglandin F(2a)in the aqueous from patients with XFS (2429 (SD 2940) pg/ml; range 400-10500 pg/ml) was significantly higher than that measured in the aqueous of age matched control patients (529.1 (226.8) pg/ml; range 325-1000 pg/ml); (p = 0.0028). Furthermore, mean ascorbic acid concentration in XFS patients (0.75 (0.39) mM; range 0.28-1.70 mM) was significantly lower than that found in control patients (1.19 (0.47) mM; range 0.53-2.4 mM); (p = 0.0005). There was a reverse correlation between 8-isoprostaglandin F(2a)and ascorbic acid concentration.

CONCLUSION

8-Isoprostaglandin F(2a)was significantly increased in the aqueous of patients with XFS, and ascorbic acid was decreased, providing evidence of a role for free radical induced oxidative damage in the pathobiology of XFS.

Ocular hemodynamics in pseudoexfoliation syndrome and pseudoexfoliation glaucoma

OBJECTIVE

To evaluate orbital blood flow velocities by using color Doppler imaging in patients with pseudoexfoliation syndrome and pseudoexfoliation glaucoma.

DESIGN

Prospective, comparative case series.

PARTICIPANTS

Twenty-eight patients with pseudoexfoliation syndrome (n = 14) or pseudoexfoliation glaucoma (n = 14) and 14 healthy control participants were included.

INTERVENTION

Color Doppler imaging was used with a 7.5-MHz probe. Evaluation of the ophthalmic, central retinal, short posterior nasal, and temporal ciliary arteries was performed, and peak systolic and end diastolic flow velocities were measured. Resistive indices were calculated.

RESULTS

When compared with the control participants, patients with pseudoexfoliation syndrome showed statistically significant decreases in the mean peak systolic velocity of the central retinal artery (11.21 +/- 2.19 cm/second; P < 0.05), and end diastolic velocities of the central retinal artery (3.00 +/- 1.03 cm/second; P < 0.005), and short posterior temporal ciliary arteries (3.50 +/- 1.74 cm/second; P < 0.005), whereas mean resistive indices of the ophthalmic artery (0.75 +/- 0.06 cm/second; P < 0.005) and central retinal artery were found to have increased (0.70 +/- 0.05 cm/second; P < 0.01). Patients with pseudoexfoliation glaucoma, when compared with the control participants, showed statistically significant decreases in the mean peak systolic and end diastolic velocities and increased mean resistive indices in all vessels measured (P < 0.05). Compared with the patients with pseudoexfoliation syndrome, patients with pseudoexfoliation glaucoma showed statistically significant decreases in the mean peak systolic velocities of the ophthalmic artery (30.07 +/- 4.00 cm/second; P < 0.05) and short posterior nasal ciliary arteries (2.35 +/- 0.09 cm/second; P < 0.05), and in the mean end diastolic velocities of the ophthalmic artery (6.28 +/- 2.12 cm/second; P < 0.05), and short posterior nasal ciliary arteries (2.35 +/- 0.09 cm/second; P < 0.05). The differences in the mean resistive indices were not statistically significant between the patients with pseudoexfoliation syndrome and the ones with pseudoexfoliation glaucoma.

CONCLUSIONS

The findings suggest that hemodynamic parameters in the retrobulbar vessels were altered in patients with pseudoexfoliation syndrome and pseudoexfoliation glaucoma; however, these alterations were more prominent in the latter group.

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.

Exfoliation syndrome and exfoliation glaucoma

Exfoliation syndrome abnormal deposition in the anterior segment of the eye of an unknown substance thought to be related to elastic fibres and basement membrane components is associated with accelerated cataract progression. increased frequency of intraoperative and postoperative complications and increased risk for glaucoma and. therefore, is a clinically important finding. A clear association has been shown with age. The syndrome occurs worldwide but its prevalence seems to vary from country to country. The best-known sign of exfoliation syndrome is deposits of greyish-white material on the anterior lens surface. Sometimes exfoliation material can also be seen at the pupillary border, on the anterior iris surface, corneal endothelium, and on the anterior vitreous face. When clinically detected, exfoliation syndrome is somewhat more often unilateral than bilateral. According to recent investigations clinically unilateral exfoliation syndrome is probably never truly unilateral but rather asymmetric, because exfoliation material has been detected ultrastructurally and immunohistochemically around iris blood vessels of the nonexfoliative fellow eyes. Indeed, electron microscopy identifies in various organs of patients with exfoliation syndrome fibrils similar to those seen in intraocular exfoliation deposits. Other clinical signs associated with exfoliation syndrome are pigment dispersion, transillumination defects of the iris and reduced response to mydriatics. In unilateral exfoliation syndrome, intraocular pressure (IOP) of the exfoliative eye is approximately 2 mmHg higher than IOP of the nonexfoliative fellow eye. Whether elevated IOP, vascular changes or exfoliation syndrome itself is the main factor causing optic nerve head damage and conversion of an exfoliative eye to glaucomatous, is not known. Glaucoma in the exfoliation syndrome has been shown to have a more serious clinical course than in primary open-angle glaucoma (POAG). At the time of diagnosis, IOP and its diurnal variation are generally higher and visual field defects tend to be greater in exfoliation glaucoma than in POAG. Because the decrease in lOP variation and lowering of the mean IOP level has been shown to improve visual field prognosis more in exfoliation glaucoma than in POAG, the glaucomatous process is considered to be more pressure-related in exfoliation glaucoma. Furthermore, progression of optic disc damage has been shown to be similar in exfoliation glaucoma and POAG when lOPs are lowered to a comparable level by the treatment. However, vascular disturbances in the posterior segment of the eye might after all be of equal importance in these two types of glaucoma; optic disc haemorrhages and venous occlusions have been reported to be as frequent in exfoliation glaucoma as in POAG. Perhaps in exfoliation glaucoma circullatory disturbances combined with high IOP lead to a particularly relentlessly progressing form of the disease.

Iris fluorescein angiography and iris indocyanine green videoangiography in pseudoexfoliation syndrome

BACKGROUND

Precise evaluation of the iris vascular pattern in pseudoexfoliation syndrome (PXS) may be difficult with iris fluorescein angiography (IFA) because of the frequent presence of a heavily pigmented iris and conspicuous late leakage. However, iris indocyanine green videoangiography (IICGV) can precisely visualize details of the iris vascular pattern. This study analyzed the utility of IICGV in detecting microvascular changes in PXS and compared these findings with those of IFA.

METHODS

Twenty-eight patients with PXS in both eyes underwent an ophthalmic examination including IFA and IICGV. IICGV was done with the IMAGEnet system H1024.

RESULTS

IICGV gave better visualization of iris hypoperfusion and anastomotic vessels whereas iris microneovascularisation was far more clearly visible on IFA. IICGV also detected iris pigment epithelium defects.

CONCLUSIONS

IICGV can be considered a useful tool for evaluation of the iris vascular pattern in PXS. Iris hypoperfusion did not appear to contribute to the development of iris microvascular changes.

Early changes in iris blood vessels in exfoliation syndrome

PURPOSE

To look for possible changes in iris blood vessels that might precede the formation of true exfoliation material, and to correlate these changes, if present, to aging of the iris.

METHODS

Iris blood vessels of 10 clinically normal irises from 10 eyes (ages: 1 day-80 years), 4 irises with exfoliation (ages: 64-80 years) and 3 irises from primary open-angle glaucoma (POAG) (ages: 27-65 years) were examined with an electron microscope.

RESULTS

Pronounced multilayering of the basal lamina around the vessels, abnormal excessive formation of microfibrils, presence of atrophic invaginations in the outer cell membranes of endothelial cells containing interlacing basal lamina, and an apparent decrease in the perivascular collagen fibers were evident in exfoliative iris vessels devoid of true exfoliation material. Similar, but much milder, changes were evident in normal aged and POAG irises.

CONCLUSIONS

Abnormal elastic tissue and/or basal lamina production plays a role early in the formation of exfoliation material around iris blood vessels.

A histopathologic study of iris changes in pseudoexfoliation syndrome. Ophthalmology. 1995;102:1279-1290. [PMID: 9097764 DOI: 10.1016/s0161-6420(95)30873-1]

PURPOSE

To investigate the histopathologic causes for the most prominent clinical observations of the iris of patients with pseudoexfoliation syndrome (PXS), particularly poor mydriasis but also atrophy of the iris pigment epithelium with anterior chamber melanin dispersion, stromal atrophy, and vascular changes.

METHODS

Thirty-three iris specimens from patients with PXS with and without glaucoma were investigated by transmission electron microscopy with special regard to sphincter and dilator muscle tissues.

RESULTS

Pseudoexfoliation fibers were observed consistently in association with fibroblasts and melanocytes in the iris stroma, endothelial cells and pericytes of vessels, both anterior and posterior pigment epithelial cells, and muscle cells of sphincter and dilator muscles. The various cell types showed uniformly surface cell membrane excavations with PXS fibers, indicating local PXS production. Focal disintegration of the pigment epithelial layers was associated with unusual PXS material aggregations along the apical aspects of epithelial cells. Compared with age-matched control specimens, the muscle cells showed, in addition to PXS production, remarkable degenerative and atrophic changes in PXS eyes.

CONCLUSION

The authors suggest that abnormal extracellular matrix production and/or vascular abnormalities leading to tissue hypoxia cause degenerative tissue changes and that atrophy of muscle cells might potentiate the reduction of dilating properties of the iris.

Pseudoexfoliation syndrome with poorly dilating pupil: a light and electron microscopic study of the sphincter area

BACKGROUND

The study was carried out to examine histological changes in the iris sphincter muscle and surrounding tissue in eyes with pseudoexfoliation syndrome (PXS).

METHODS

Seventeen patients with PXS, 14 of them having capsular glaucoma, were enrolled into the study. Iris biopsies were obtained during extracapsular cataract extractions (ECCE) requiring sphincterotomies. Thirteen biopsy specimens underwent histological examination by light microscopy, and four were examined with the electron microscope. Three iris biopsies from cadaver eyes and one obtained during ECCE from a patient with a miotic pupil (no PXS) served as control specimens on light microscopy. Electron microscopic controls included three iris specimens from cadavers.

RESULTS

In the light microscopic examination, blood vessel walls were stained with Congo Red in seven of the 13 PXS specimens. In three of these seven specimens the stromal tissue was extensively fibrotized, and in two specimens fibrosis was moderate. Distinct stromal fibrosis was also observed in one and moderate fibrosis in two PXS specimens negative for amyloid. The control specimens were not positive for Congo Red, but stromal tissue was moderately fibrotized in one specimen. Light microscopy did not reveal differences in muscle tissue between PXS and control specimens. Electron microscopically, however, the muscle tissue was fibrotic or disorganized in three PXS specimens and in one control specimen. Fibrils, similar to the fibrillar component of pseudoexfoliation material described in previous studies, were found in intimate association with the capillary basal lamina in all of the PXS specimens showing muscular fibrosis.

CONCLUSIONS

These findings support the theory that PXS is associated with amyloid, and in some PXS eyes miosis is connected with degenerative changes both in the stromal tissue and in the muscular layer of the iris.

Immunogold study of non-collagenous matrix components in normal and exfoliative iris

The present investigation was undertaken to determine if some of the components of exfoliation material in iris tissue were unique to exfoliation or were part of normal iris architecture. Eleven normal iris specimens and 10 exfoliative iris specimens were processed for cryoultramicrotomy and London resin white embedding. Immunogold electron microscopy was used to investigate the fine structural distribution of amyloid P component, elastin, entactin, fibronectin, gp115, and vitronectin in normal iris and their association with exfoliation material. Exfoliation material was positive for amyloid P component and possibly gp115, neither of which were present in normal iris tissue. Elastin and fibronectin were present in the normal iris stroma but were not associated with exfoliation material. The distribution of amyloid P component in the vessel lumen and wall led to the conclusion that amyloid P is a serum contaminant. The presence of gp115 in exfoliation material represents the synthesis of a component novel to the iris vascular cell synthetic repertoire.