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Gottfried O H Naumann

Publications and source records attributed to Gottfried O H Naumann.

At least 19 recordsLinked to original sources
PubMed2006

Long-term refractive and visual outcome after penetrating keratoplasty only versus the triple procedure in Fuchs' dystrophy.

BACKGROUND: Long-term refractive and visual outcome after penetrating keratoplasty (PK) only and the triple procedure in eyes with Fuchs' endothelial dystrophy were assessed and compared. DESIGN: Retrospective, non-randomized, cross-sectional, clinical, single-centre study. METHODS: Ninety-two eyes of 87 patients were divided into two groups. Group 1 consisted of 28 eyes (mean age 62+/-13 years) that had undergone PK only and group 2 consisted of 64 eyes (mean age 69+/-10 years) that had undergone the triple procedure. Inclusion criteria were: (1) Fuchs' dystrophy, (2) central nonmechanical trephination, (3) double-running suturing technique and (4) availability of 'two-sutures-out' findings. In all eyes, a central trephination was performed (donor trephination from the epithelial side) using the 193-nm excimer laser along metal masks with eight 'orientation teeth/notches'. A double-running 10-0 nylon suture was applied in all eyes. Subjective refractometry (trial glasses), standard keratometry (Zeiss) and corneal topography analysis (TMS-1, Tomey) were performed in all eyes with 'two-sutures-in', 'one-suture-out', and 'two-sutures-out'. Main outcome measures included refractive cylinder, keratometric and topographic net astigmatism, keratometric and topographic central power, best-corrected visual acuity (BCVA), spherical equivalent (SE) of manifest refraction, surface regularity index (SRI), surface asymmetry index (SAI), and regularity of keratometry mires. RESULTS: The results were compared between the two groups (i.e. group 1 vs group 2) at various stages (i.e. 'two-sutures-in', 'one-suture-out', 'two-sutures-out'). Refractive cylinder in dioptres [D] was 2.5/2.0/2.5 vs 2.0/1.5/3.0, keratometric astigmatism [D] was 3.5/2.6/3.0 vs 3.5/3.1/3.5 and topographic astigmatism [D] was 3.9/4.1/4.9 vs 4.2/5.0/5.1. Keratometric central power [D] was 41.7/42.4/43.8 vs 41.5/41.9/43.3 and topographic central power [D] was 42.3/43.6/43.7 vs 42.6/41.8/44.3. BCVA was 0.5/0.6/0.6 vs 0.5/0.5/0.5. SE [D] was 0.0 /0.0/-0.5 vs -0.5/-0.5/-1.1. SRI was 1.5/1.1/1.0 vs 1.4/1.4/1.2 and SAI was 1.0/0.8/1.0 vs 1.3/1.2/1.0. The proportion of 'regular' and 'mildly irregular' keratometry mires was 44% / 69% / 68% vs 29% / 46% / 66%. The differences between the two groups did not reach statistical significance at any of the stages. CONCLUSIONS: Refractive and visual outcome after the triple procedure did not differ significantly from that after PK only. Therefore, we recommend the triple procedure in elderly patients with Fuchs' dystrophy and cataract to avoid delayed visual rehabilitation and a second surgical procedure.

Adult↗
PubMed2006

Ocular and systemic pseudoexfoliation syndrome.

PURPOSE: To provide an update on most recent developments regarding ocular and systemic manifestations and complications, clinical diagnosis and management, and molecular pathophysiology of pseudoexfoliation (PEX) syndrome, and to discuss future tasks and challenges in this field. DESIGN: Perspective. METHODS: Review of recent literature and authors' own clinical and laboratory studies. RESULTS: PEX syndrome is a common age-related generalized fibrotic matrix process of worldwide significance, which may not only cause severe chronic open-angle glaucoma and cataract, but also a spectrum of other serious spontaneous and surgical intraocular complications. Recent progress and advances have led to (1) improvements in clinical management by understanding the effects of the PEX process on ocular tissues, by refining diagnostic criteria, by applying new treatment regimes, and by developing preventive strategies to reduce surgical complications; (2) increasing evidence for systemic associations of PEX with cardiovascular and cerebrovascular morbidity; and (3) new insights into the molecular pathophysiology by analyzing the composition of PEX material, the differential gene expression of affected tissues, and key factors involved in pathogenesis. The current pathogenetic concept describes PEX syndrome as an elastic microfibrillopathy involving transforming growth factor-beta1, oxidative stress, and impaired cellular protection mechanisms as key pathogenetic factors. CONCLUSIONS: Future tasks and challenges comprise epidemiologic prevalence and genetic studies of PEX syndrome, prospective randomized clinical and histopathological screening studies on its systemic manifestations and associations, and intensified basic research on differential protein and gene expression, animal and in vitro models, as well as potential biomarkers for PEX syndrome and its associated glaucoma.

Exfoliation Syndrome↗
PubMed2006

Histologic and ultrastructural changes in corneas with granular and macular dystrophy after excimer laser phototherapeutic keratectomy.

PURPOSE: The histologic changes after phototherapeutic keratectomy (PTK) in corneas with granular and macular dystrophy were studied. METHODS: We studied 3 corneas of 2 patients (1 granular, 2 macular dystrophy), who underwent penetrating keratoplasty (PK) at 0.8, 2.16, and 3.25 years after PTK; and 11 corneas (controls) from 10 PK patients (5 granular, 6 macular dystrophy) by light microscopy and by transmission electron microscopy. PTK was performed by using the Asclepion-Meditec MEL 60 excimer laser. RESULTS: After PTK the epithelium (15-40 versus 5-100 microm), and the upper stromal collagen lamella thickness (50-75 versus 50-100 microm) were less irregular than for the controls. In 1 eye (macular dystrophy) 10 months after PTK an acid mucopolysaccharide-positive band was detected in the subepithelial stroma, which could be removed by hyaluronic acid digestion. This fact suggests that it was "haze" formed after PTK, rather than a subepithelial recurrence of the dystrophy. All PTK corneas had deposits in the mid- and posterior stroma. Concerning controls, deposits were detected under the epithelium in all corneas. Electron microscopy of the study corneas revealed a mostly continuous basal lamina, occasionally forming projections into the subepithelial stroma, and large numbers of well-developed hemidesmosomes (5.2 +/- 0.8 per microm membrane length) present at greater density than in the controls (3.5 +/- 0.8). CONCLUSIONS: In stromal dystrophies, PTK was effective in removing large subepithelial stromal plaques. There were no subepithelial recurrences, and hemidesmosome density was increased.

Adult↗
PubMed2006

Corneal curvature after penetrating keratoplasty before and after suture removal: a comparison between keratoconus and Fuchs' dystrophy.

PURPOSE: To assess the differences concerning corneal curvature and visual acuity after penetrating keratoplasty (PKP) comparing keratoconus (KC) and Fuchs' dystrophy (FUCHS). METHODS: Inclusion criteria for this prospective, comparative, interventional study were: (1) one surgeon, (2) central round nonmechanical excimer laser PKP without previous surgery, (3) FUCHS (n = 35) or KC (n = 52), (4) standardized graft size (7.5-8.0 mm) and technique, 16-bite double running cross-stitch suture. In 69% of FUCHS, a triple procedure was performed. The main outcome measures were: keratometric astigmatism, surface regularity index, surface asymmetry index, keratometric central corneal power and best-corrected visual acuity before (1.2 +/- 0.4 years) and after suture removal (1.8 +/- 0.6 years). RESULTS: Astigmatism did not differ significantly between KC and FUCHS (p > 0.1) before (3.3 dpt vs. 3.5 dpt median) and after suture removal (2.5 dpt vs. 3.0 dpt). Surface regularity index and surface asymmetry index were significantly higher in FUCHS than in KC (p < 0.001) at both time stages. Central power was significantly greater in KC than in FUCHS (p < 0.001) with sutures in place. Due to a significant steepening in FUCHS and flattening in KC, this difference was no longer present after suture removal. Visual acuity in KC exceeded that in FUCHS before (0.68 vs. 0.60) and even more after suture removal (0.86 vs. 0.60; p < 0.001). CONCLUSIONS: In KC, keratometric astigmatism is not higher than in FUCHS after PKP. After suture removal, graft topography in KC and FUCHS may be expected to regularize and the excessive corneal flattening in FUCHS to normalize in the mid-term.

Adult↗
PubMed2006

Clusterin deficiency in eyes with pseudoexfoliation syndrome may be implicated in the aggregation and deposition of pseudoexfoliative material.

PURPOSE: To determine the role of the extracellular chaperone clusterin in the pathophysiology of pseudoexfoliation (PEX) syndrome/glaucoma, which is characterized by the stable deposition of abnormal extracellular fibrillar material in anterior segment tissues. METHODS: Real-time PCR, in situ hybridization, and immunohistochemistry were applied to analyze the mRNA and protein expression of clusterin in PEX eyes of patients without and with glaucoma and to compare them with eyes of patients with primary open-angle glaucoma and angle-closure glaucoma and with normal control eyes. Aqueous levels of clusterin were determined by Western blot analysis. Real-time PCR and Western blot analysis were used to study the effect of TGF-beta1, which is significantly increased in the aqueous humor of PEX eyes, on clusterin expression by nonpigmented ciliary epithelial cells in vitro. RESULTS: Clusterin mRNA was ubiquitously expressed in most ocular cells and tissues, particularly in the epithelium of ciliary processes, whereas the protein was mostly located to extracellular structures, such as ocular basement membranes and stromal fibers. Real-time PCR and in situ hybridization displayed significant downregulation of clusterin mRNA in all anterior segment tissues of PEX eyes, irrespective of the presence or type of glaucoma, compared with normal and glaucomatous control eyes, whereas posterior segment tissues did not show any differential expression. A generally decreased immunoreactivity, but a prominent binding of clusterin to all PEX deposits, could be observed in ocular tissues of PEX eyes. Clusterin levels in aqueous humor were significantly reduced in eyes of patients with PEX syndrome compared with normal and glaucomatous control eyes. The expression of clusterin mRNA and protein in nonpigmented ciliary epithelial cells was significantly downregulated by TGF-beta1 in vitro. CONCLUSIONS: Considering the known role of clusterin as a highly efficient extracellular chaperone, its deficiency in the anterior segment of PEX eyes may promote the stress-induced aggregation and stable deposition of the pathologic extracellular matrix product characteristic of PEX syndrome.

Aged↗
PubMed2006

Intra-individual variability of penetrating keratoplasty outcome after excimer laser versus motorized corneal trephination.

PURPOSE: To assess the intra-individual variability of outcomes after penetrating keratoplasty by comparing mechanical and nonmechanical corneal trephination. METHODS: Fifteen patients (30 eyes, 16 with keratoconus and 14 with Fuchs' dystrophy; median age at penetrating keratoplasty 56.3/53.5 years) were assessed whose trephination was performed using a motor trephine in one eye and the 193-nm excimer laser (MEL 60, Carl Zeiss-Meditec) in the other eye by one experienced surgeon. Subjective refractometry, standard keratometry, and corneal topography were used to assess best spectacle-corrected visual acuity (BSCVA); spherical equivalent refraction; keratometric and topographic central corneal power; refractive, keratometric, and topographic astigmatism; surface regularity index; surface asymmetry index; and potential visual acuity preoperatively, before first suture removal (at 1 year), and at last available follow-up after final suture removal but before additional surgery (1.3 and 1.9 years, respectively). RESULTS: Before first suture removal BSCVA was significantly higher (0.7 vs 0.5; P=.008) after excimer laser trephination. At the end of follow-up, refractive/ keratometric/topographic astigmatism (2.20/2.10/2.40 diopters [D] vs 5.00/6.00/7.10 D) and surface regularity index (0.8 vs 1.1) were significantly lower (P=.02, P=.005, P=.01, and P=.03, respectively) and potential visual acuity was significantly higher (0.9/0.6; P=.02) after excimer laser trephination. CONCLUSIONS: During long-term follow-up, all-sutures-out postkeratoplasty astigmatism and surface regularity are superior in the eye where nonmechanical excimer laser was applied in contrast to the fellow eye with motor trephination in the same individual.

Adult↗
PubMed2005

Inverse mushroom-shaped nonmechanical penetrating keratoplasty using a femtosecond laser.

PURPOSE: To demonstrate the feasibility of an inverse mushroom-shaped nonmechanical corneal trephination using a femtosecond laser in a noncontact manner. DESIGN: Experimental study. METHODS: In this laboratory study, 10 polymethylmethacrylate (PMMA) blocks and 20 porcine corneas were treated with an industrial femtosecond laser source. The trephination profile consisted of (1) a 7- or 6-mm diameter cylinder from the anterior chamber, (2) an intermediate horizontal connecting plane, and (3) a concentric 5- or 4-mm diameter cylinder upwards. RESULTS: Applying appropriate combinations of pulse energy and spacing, trephination took less than 60 seconds. In porcine eyes, light microscopy displayed trephination edges delineated by partly confluent gas bubbles (10-40 mum) with tissue bridges in between. By TEM, the cut edges were lined by a delicate, electron-dense layer (5-40 nm). CONCLUSIONS: Femtosecond laser technology seems to offer a promising approach towards minimally invasive self-sealing "no-stitch keratoplasty."

Agaricales↗
PubMed2005

Repeat keratoplasty for correction of high or irregular postkeratoplasty astigmatism in clear corneal grafts.

PURPOSE: To evaluate the functional results of repeat penetrating keratoplasty in clear corneal grafts with high/irregular postkeratoplasty astigmatism. DESIGN: Retrospective, longitudinal, single-center, consecutive clinical case series. METHODS: We studied 17 eyes (16 keratoconus, 1 Fuchs' dystrophy) of 16 patients (age, 54.9 +/- 12.6 years). They were treated with repeat PK, performed using the 193-nm Zeiss-Meditec MEL-60 excimer laser using round metal masks (diameter, 7.5-8.0 mm), and employing double running sutures. main outcome measures: Subjective refractometry, standard keratometry, and corneal topography (Tomey TMS-1) were used to assess best-corrected visual acuity (BCVA), spherical equivalent (SEQ), keratometric and topographic central corneal power (CP), refractive, keratometric and topographic astigmatism, surface regularity index (SRI), surface asymmetry index (SAI), and potential visual acuity (PVA) preoperatively, before and after first suture removal (1.1 year), and after second suture removal (1.8 years). RESULTS: Visual acuity improved significantly (BCVA from 0.2-0.5, P = .04 or better) for all postoperative measurements. CP decreased significantly, but SEQ did not change. All measures of astigmatism and SRI and SAI values showed postoperative improvement with sutures in place; however, astigmatism increased significantly after second suture removal. CONCLUSIONS: With all-sutures-in, BCVA and astigmatism improve significantly after repeat PK for high/irregular astigmatism. However, to present significant increase in astigmatism, final suture removal should be postponed as long as possible in such eyes.

Adult↗
PubMed2005

Spontaneous long-term changes of corneal power and astigmatism after suture removal after penetrating keratoplasty using a regression model.

PURPOSE: To assess the diagnosis-based spontaneous long-term changes in corneal power and refraction with a regression model in the all-sutures-out time period following non-mechanical penetrating keratoplasty (PK). DESIGN: Retrospective non-randomized clinical trial. METHODS: setting: Clinical practice. study population: 147 eyes [47 Fuchs dystrophy (FD); 100 keratoconus (KC)] were studied after suture removal in this retrospective longitudinal study. main outcome measures: Zeiss keratometry [equivalent power (KEQ) and astigmatism (KAST)], corneal topography analysis [equivalent power (TEQ) and astigmatism (TAST)], and subjective refractometry [spherical equivalent (SEQ) and refractive cylinder (RAST)] were assessed in at least three up to 16 ophthalmologic examinations in the all-sutures-out time period. observation procedure: The time course of each target variable was analyzed in a longitudinal manner (time interval > or = 12 months) separately for each patient with a linear regression model. RESULTS: Post-keratoplasty follow-up ranged from 31 months to 10.3 years. In the linear regression model, the annual change in FD/KC showed an increase/a decrease in KEQ (0.29 +/- 0.50/-0.63 +/- 0.46 diopters, P = .02) and an increase/a decrease in TEQ (0.37 +/- 0.54/-0.69 +/- 0.49 diopters, P = .04) corresponding to a decrease/an increase in SEQ (-0.31 +/- 0.47/0.63 +/- 0.43 diopters, P = .02). KAST/TAST/RAST showed a minimal annual decrease (-0.06 +/- 0.41/-0.05 +/- 0.45/-0.06 +/- 0.41 diopters) in FD but an increase in KC (0.46 +/- 0.41/0.51 +/- 0.43/0.46 +/- 0.38 diopters) (P = .05/0.06/0.12). CONCLUSIONS: In the follow-up after post-keratoplasty suture removal, patients with FD/KC tend to develop a spontaneous myopic shift (steepening of the cornea)/hyperopic shift (flattening of the cornea). In contrast with those with FD, patients with KC should be counseled on the fact that astigmatism may increase again over time after suture removal.

Astigmatism↗
PubMed2005

Selective upregulation of the A3 adenosine receptor in eyes with pseudoexfoliation syndrome and glaucoma.

PURPOSE: Adenosine is increasingly released in metabolic stress conditions, like hypoxia or ischemia, and regulates many physiologic processes, such as aqueous humor secretion and intraocular pressure, via activation of four adenosine receptors. In the current study, the role of the adenosine system in the pathophysiology of pseudoexfoliation (PEX) syndrome, which is typically associated with anterior chamber hypoxia and elevated intraocular pressure, was examined. METHODS: RT-PCR, Northern hybridization, in situ hybridization, and immunohistochemistry were applied to analyze the mRNA and protein expression of the adenosine receptor subtypes A1, A2A, A2B, and A3 in anterior segment tissues of PEX eyes, without and with glaucoma, in comparison to eyes with primary open-angle or angle-closure glaucoma and normal control eyes. Real-time PCR was used to study the effect of hypoxia and oxidative stress on adenosine receptor expression by nonpigmented ciliary epithelial cells in vitro. Levels of adenosine and its catabolites inosine, hypoxanthine, and xanthine were measured in cell culture supernatants and aqueous humor samples by HPLC. RESULTS: All four adenosine receptor subtypes (A2A > A1 > A2B > A3) were coexpressed but differently distributed in the ciliary epithelium of control eyes, with the A3 receptor being localized to the basolateral membrane infoldings of the nonpigmented epithelial cells. A selective, approximately 10-fold upregulation of A3 receptor mRNA and protein was consistently found in the nonpigmented ciliary epithelium of all PEX eyes, with and without glaucoma, compared with the normal and glaucomatous control eyes. Significant upregulation of A3 receptor message in nonpigmented epithelial cells was induced by both hypoxia and oxidative stress in vitro, together with increased levels of inosine, hypoxanthine, and xanthine in the supernatants. Levels of adenosine and its catabolites, however, were not significantly elevated in the aqueous humor of patients with PEX. CONCLUSIONS: Considering the known role of the A3 adenosine receptor in modulating aqueous humor secretion, its selective, probably hypoxia-induced upregulation in the ciliary epithelium may not only confer cytoprotection but also influence aqueous humor dynamics and may be accessible to therapeutic intervention in patients with PEX.

Adenosine↗
PubMed2005

Differential gene expression in pseudoexfoliation syndrome.

PURPOSE: To identify and characterize genes differentially expressed in anterior segment tissues of eyes with pseudoexfoliation (PEX) syndrome and glaucoma. METHODS: Anterior segment tissues (iris, ciliary processes, lens epithelium) were obtained from eight surgically enucleated eyes with PEX-associated open-angle or closed-angle glaucomas and eight age-matched glaucomatous control eyes without PEX. cDNA libraries were generated from three PEX and three control specimens, and their gene expression patterns were compared by means of cDNA subtraction. Differentially expressed clones from the subtracted cDNA libraries were sequenced, and their differential expression was verified by means of RT-PCR, virtual Northern blot analysis, and in situ hybridization with specific RNA probes. RESULTS: Subtraction of cDNA libraries identified 27 candidate genes for differential expression in PEX tissues, of which 23 genes were confirmed by virtual Northern blot, RT-PCR, and in situ hybridization. One set of genes consistently upregulated in anterior segment tissues from different patients with PEX comprised latent transforming growth factor binding proteins (LTBP-1 and -2), which are structural components of elastic microfibrils, the cross-linking enzyme transglutaminase-2 (TGase-2), tissue inhibitor of matrix metalloproteinase-2 (TIMP-2), A-kinase anchor protein-2 (AKAP-2), apolipoprotein D, and the adenosine receptor-A3 (AdoR-A3). Genes reproducibly downregulated in PEX tissues included TIMP-1, clusterin, microsomal glutathione-S-transferase-1 (mGST-1), and serum amyloid A1. Further transcripts, such as elastase, GST-T1, integrin beta4, and dehydrocholesterol reductase, did not show a consistent differential expression pattern in tissues obtained from different patients. Although fibrillin-1 was not isolated from subtracted cDNA libraries, upregulated expression of this elastic microfibrillar component was also demonstrated by RT-PCR and in situ hybridization. CONCLUSIONS: Differentially expressed genes with a high level of reproducibility in different tissues and different patients with PEX syndrome are mainly related to extracellular matrix metabolism and cellular stress. The underlying pathophysiology of PEX syndrome appears to be associated with an excessive production of elastic microfibril components, enzymatic cross-linking processes, a proteolytic imbalance between matrix metalloproteinases and their inhibitors, and increased cellular and oxidative stress supporting the notion of PEX syndrome as a stress-induced elastic microfibrillopathy.

Aged↗
PubMed2004

Elevated homocysteine levels in aqueous humor of patients with pseudoexfoliation glaucoma.

PURPOSE: To determine total homocysteine levels in aqueous humor of pseudoexfoliation open-angle glaucoma patients. DESIGN: Case-control study. METHODS: Total homocysteine levels were measured by enzyme-linked immunosorbent assay in aqueous humor and plasma of 29 patients with pseudoexfoliation glaucoma and 31 control patients with cataract. Patients with factors affecting homocysteine levels were excluded. RESULTS: We observed significantly elevated (twofold) homocysteine levels in the aqueous humor of the glaucoma patients (Z = -5.11, P <.0001). Additionally, the calculated ratio (plasma:aqueous humor) was significantly lower in these patients (Z = -3.57, P <.001), and aqueous homocysteine was significantly correlated with their respective elevated plasma levels (r =.42, P =.02). CONCLUSIONS: Because homocysteine induces vascular injury and alterations of extracellular matrix, high aqueous homocysteine may trigger the abnormal matrix accumulation characteristic. It may reflect the proposed impairment of the blood-aqueous barrier of pseudoexfoliation open-angle glaucoma and be involved in its pathogenesis.

Aged↗
PubMed2004

Morphometric analysis of deposits in granular and lattice corneal dystrophy: histopathologic implications for phototherapeutic keratectomy.

OBJECTIVE: To quantify the distribution and size of deposits in granular and lattice corneal dystrophies and to estimate the impact of these findings on the potential benefit of phototherapeutic keratectomy (PTK) as primary treatment in these corneal disorders. METHODS: Central histologic sections of consecutive corneal buttons (34 granular dystrophy specimens of 27 patients (mean age 53 +/- 12 years) and 20 lattice dystrophy specimens of 20 patients (mean age 50 +/- 17 years) obtained from central penetrating keratoplasty were examined by light microscopy using Masson trichrome and Congo Red stains. Localization and anterioposterior diameter of the most superficial, the deepest, and the largest deposits were quantified in the central and the two peripheral thirds of the specimens. Bowman layer status and thickness of the epithelium were recorded. The clear central corneal zone size before and after a hypothetical superficial PTK (100-microm ablation) was calculated. RESULTS: Central deposits in granular dystrophy were mostly superficial (mean distance from the epithelium 28 +/- 19 microm) and associated with Bowman layer and epithelial changes. In lattice dystrophy, deposits were mostly midstromal (mean distance from the epithelium 79 +/- 54 microm, P < 0.001) with a larger scatter, showing minor superficial involvement. After a fictitious PTK, a significant increase in mean clear central zone was achieved (P = 0.004). This increase in mean clear central zone was more pronounced in granular (from 484 +/- 389 microm to 1451 +/- 1954 microm) than in lattice (from 258 +/- 183 microm to 846 +/- 784 microm) dystrophy (P = 0.004). Deposits were completely removed in 22% of the granular dystrophy samples. In both dystrophies, a clear central "pinhole" greater than 1 mm in diameter was achieved in around one third of corneas. CONCLUSION: According to the histopathologic corneal deposit size and distribution, PTK may be an effective treatment to increase visual acuity in patients with granular dystrophy more than in those with lattice dystrophy, to delay or even avoid penetrating keratoplasty.

Corneal Dystrophies, Hereditary↗
PubMed2004

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.

Exfoliation Syndrome↗
PubMed2003

Corneal shrinkage induced by nonmechanical Q-switched erbium:YAG laser trephination for penetrating keratoplasty in porcine eyes.

PURPOSE: To assess the degree of corneal diameter shrinkage induced by Q-switched mid-infrared laser corneal trephination for penetrating keratoplasty in an experimental model. METHODS: Corneal trephination was performed in 80 enucleated porcine eyes fixed in a holder centered on an automated globe rotation device, by Q-switched (2.94 microm) Er:YAG laser along open masks. Four types of masks were used to protect the underlying corneal tissue: metal masks (donor and recipient) and ceramic masks (donor and recipient). Two spot diameters (0.65 mm and 0.96 mm) were combined with two energy settings (40 mJ/pulse and 50 mJ/pulse) for each of the masks used. Repetition rate was fixed at 5 Hz. Diameters of donor buttons/recipient beds (horizontal and vertical) were measured immediately after the trephination and compared to the given mask size. RESULTS: Minimum corneal shrinkage was found in the recipient metal mask group (mean +/- SD=0.3+/-0.4%) with 50 mJ pulse energy and 0.65 mm spot diameter (in the horizontal diameter), while the maximum shrinkage (5.3+/-2.8%) was found in the donor metal mask group with 50 mJ pulse energy and 0.96 mm spot diameter. Corneal shrinkage was less pronounced in recipient beds than in donor buttons (P<0.01). The differences in shrinkage between the use of ceramic and metal masks were insignificant (P>0.05). Mean induced corneal diameter discrepancies between the donor button and the recipient bed (with metal and ceramic masks) were 2.5% and 2.5% in vertical diameter and 3.4% and 2.4% in horizontal diameter. CONCLUSIONS: The Q-switched Er:YAG laser experimental corneal trephination for penetrating keratoplasty may induce minor degrees of corneal diameter shrinkage in donor buttons and recipient openings. Oversizing of donor masks by 0.25-0.35 mm (i.e. 3-4% of graft size) may be a valid option to avoid refractive consequences.

Animals↗
PubMed2003

Nonmechanical Q-switched erbium:YAG laser trephination for penetrating keratoplasty: experimental study on human donor corneas.

OBJECTIVE: To assess the alterations in human donor corneal tissue induced by Q-switched erbium (Er):YAG laser corneal trephination. METHODS: Thirty human corneoscleral donor buttons unsuitable for transplantation were placed in an artificial chamber on an automated rotation device. Corneas were trephined with a Q-switched Er:YAG laser (wavelength, 2.94 microm; pulse duration, 400 nanoseconds) along (donor and recipient) aluminum silicate (ceramic) open masks. A spot diameter of 0.65 mm, energy setting of 50 mJ/pulse, and repetition rate of 5 Hz were used. Corneal thermal damage and cut regularity were quantitatively assessed in 24 corneas processed for light microscopy and by transmission and scanning electron microscopy. RESULTS: The stromal thermal damage was the highest (mean [SD], 8.0 [2.7] microm) at a 150-microm cut depth and decreased downward. Cut regularity was very good and did not significantly differ between donors and recipients. Scanning electron microscopy confirmed that the cuts were highly regular; transmission electron microscopy revealed 2 distinctive subzones within the stromal thermal damage zone. CONCLUSIONS: Thermal damage induced by Q-switched Er:YAG nonmechanical corneal trephination was low, and the regularity of the cuts was very good. CLINICAL RELEVANCE: The Q-switched Er:YAG laser may have the potential to become an alternative to the excimer laser for nonmechanical penetrating keratoplasty.

Cornea↗
PubMed2003

Nonmechanical posterior lamellar keratoplasty using the femtosecond laser (femto-plak) for corneal endothelial decompensation.

PURPOSE: To assess the potential of a short pulsed laser to cut a posterior graft and bed for posterior lamellar keratoplasty (PLAK). DESIGN: Experimental study. METHODS: Using the laser FEMTEC (20/10 Perfect Vision, Heidelberg, Germany), posterior lamellar dissections (wave length approximately 1 microm, pulse energy < 10 microJ, spot size <10 microm, repetition rate 12.5 kHz, 6-mm-7 mm diameter, 31 s and 90 s) were performed in 18 freshly enucleated porcine eyes and 10 human donor corneas starting from the anterior chamber and ending with the lamellar bed. RESULTS: Before removal, 50 microm to 500 microm-thick flaps were delineated by partly confluent gas bubbles (maximum 2-mm long) with minute tissue bridges (typically 5- to 10 microm) in between. Scanning electron microscopy displayed smooth cut surfaces and rectangular corners with minor remaining tissue bridges (approximately 5 microm). By transmission electron microscopy, the cut edges were lined by a delicate, electron-dense layer (5 nm-10 nm in width) and essentially normal adjacent collagen fibers. CONCLUSIONS: Femtosecond laser technology seems to offer a promising approach to minimally invasive posterior lamellar keratoplasty (femto-PLAK) through small tunnel incisions in corneal endothelial diseases.

Animals↗