Penetrating keratoplasty 1981-1988: clinical indications and pathologic findings

We analyzed 740 penetrating keratoplasty specimens received at the Intermountain Ocular Research Center from 1981 through 1988. These corneal specimens were categorized by clinical indications for removal and pathologic confirmation of the clinical findings. Keratoconus was the most common indication for a penetrating keratoplasty (22.8%). This was closely followed by pseudophakie bullous keratopathy (21.8%), regraft (13.2%), scarring (8.9%), aphakic bullous keratopathy (6.4%), and Fuchs' endothelial dystrophy (5.8%). Since 1984, pseudophakic bullous keratopathy has surpassed keratoconus as the most common indication for penetrating keratoplasty (27.3% vs. 20.2%). Pseudophakic bullous keratopathy was found more commonly than keratoconus in each of the last four years of this study. The most common type of intraocular lens associated with pseudophakic bullous keratopathy was an anterior chamber lens (52.8%), with iris-fixated (26.7%) and posterior chamber (17.4%) lenses seen less frequently.

[Cornea guttata and Fuchs' endothelial-epithelial dystrophy. Clinico-histologic study of 73 patients]

In a retrospective, clinico-histological study, 84 corneas from 73 patients with diagnosed Fuchs' dystrophy (FD) were examined after penetrating keratoplasty. Seven types of posterior corneal degeneration were found: six with diversely arranged and pronounced guttae and a thickened Descemet's membrane, and a seventh with no guttae in either eye. This last variant appeared histologically in only two patients. Whether it represents a different syndrome can only be speculated. Our study showed, however, that the frequency of cornea guttata (CG) in FD is statistically significant in all the histological variants.

Keratoconus and Fuchs' corneal endothelial dystrophy in a patient and her family

A 44-year-old patient with bilateral keratoconus and bilateral Fuchs' dystrophy underwent penetrating keratoplasty. Examination of the patient's family revealed keratoconus in the patient's son and central guttata and abnormal endothelial cells in the patient's mother and daughter. Histopathologic evaluation of the corneal button demonstrated a thinned central epithelium and folds and keratocytes in Bowman's layer consistent with keratoconus. Central guttata, subepithelial bullae, and a decreased number of endothelial cells, consistent with Fuchs' endothelial dystrophy, were also seen. This case demonstrates that two distinct familial corneal diseases can occur in the same patient. Although one cannot conclude inheritance patterns based on this limited evaluation, the findings in this family support previous observations that keratoconus can be familial, and that Fuchs' corneal dystrophy has a female predilection with an autosomal-dominant inheritance pattern.

Moderate Fuchs' endothelial dystrophy ATPase pump site density

The Na+, K+-ATPase pump site density on corneal endothelial cells from Fuchs' endothelial dystrophy corneas has been shown to be drastically decreased in end-stage disease (McCartney et al, Invest Ophthalmol Vis Sci 28:1955, 1987) and significantly increased in the early stages (Geroski et al, Ophthalmology 92:759, 1985) as compared to normal endothelium. In order to provide values for corneas between these two extremes, eye bank corneas from donors with no evidence of corneal edema but with guttata across the extent of the cornea were processed for autoradiography as well as immunohistochemistry. Pump site density was increased compared to end-stage disease but was less than values reported for either functional tissue or early stage disease. Similarly, immunohistochemistry results showed the amount of Na+, K+-ATPase antibody localization to be increased in respect to end-stage disease, but reduced as compared to functional tissue. These results suggest that pump site density on endothelial cells affected with Fuchs' endothelial dystrophy follows a gradual decline towards end-stage disease values as opposed to a sudden sharp deterioration after an initial increase.

Corneal hydration control in Fuchs' dystrophy

Corneal hydration control was tested in 22 patients with Fuchs' dystrophy, and eight subjects of similar age without the disease, by measuring the corneal thickness recovery from swelling induced by hypoxia or following overnight sleep. Measurement precision was enhanced by using a modified optical pachometer and conducting two test procedures which were analyzed by a coupled exponential model. We have identified three parameters of the recovery from corneal swelling which may be used to describe hydration control: percent recovery per hour (PRPH) (mean 25.4% for Fuchs' and 34.2% for normals), time for 95% of corneal thickness recovery (mean 10.2 hr for Fuchs' and 7.1 hr for normals), and the open-eye steady-state thickness (mean 562 microns for Fuchs' and 537 microns for normals.) A PRPH of 17.1%/hr was identified as the minimum below which the cornea could not regain its open-eye steady state during the entire day and approaches decompensation. Our test procedure quantifies the corneal hydration control mechanism and may provide a test of endothelial function which can be used to monitor the progression of Fuchs' disease and guide decisions related to corneal surgery.

The corneal endothelial dystrophies

Three major types of corneal endothelial dystrophies i.e. congenital hereditary corneal oedema, posterior polymorphous dystrophy and Fuchs endothelial dystrophy are reviewed. Clinical and histopathological characteristics are discussed and results of surgical management presented.

Epithelial abnormalities in chronic corneal edema: a histopathological study

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A comparison of corneal endothelial morphology in cornea guttata, Fuchs' dystrophy and bullous keratopathy

Changes on corneal endothelial specular microscopy were compared in 14 patients with cornea guttata, 4 patients with Fuchs' corneal dystrophy and 19 patients with various forms of bullous keratopathy. The patients with cornea guttata showed well marked guttae 1 to 6 endothelial cells in diameter in the endothelial mosaic and in the relief mode while the endothelial mosaic was usually otherwise within normal limits. In 2 patients with Fuchs' dystrophy the endothelium could be examined, showing gross guttae but a few areas of relatively normal endothelial cells. The unaffected eye of 3 other patients showed findings similar to cornea guttata, but with some reduction in endothelial cell count in 2 patients. The patients with bullous keratopathy fell into 2 groups, one with gross reduction in cell count in a markedly abnormal endothelial cell mosaic, the other a mixed group with moderate reduction in cell count and numerous guttae. Some miscellaneous cases included one of aphakic peripheral bullous keratopathy, one associated with cyclitis and aphakia and 2 with idiopathic non-surgical bullous keratopathy. We believe the corneal endothelium is not grossly abnormal away from the guttae in Fuchs' dystrophy, but the gross guttata formation determines the endothelial dysfunction.

ATPase pump site density in human dysfunctional corneal endothelium

Proper corneal hydration is maintained by a Na, K-ATPase pump located in the lateral membranes of the endothelial cells. In dysfunctional corneas this pumping action appears to break down as the corneas become edematous. In order to provide quantitative and qualitative data on the Na, K-ATPase pump site density on dysfunctional and functional human corneal endothelial cells, the present study has employed both autoradiographic and histochemical techniques. Computer-assisted morphometrics and statistical analysis showed that there was a significant reduction (P less than 0.001) in 3H-ouabain binding, and thus ATPase pump sites, in the three types of corneas (Fuchs' endothelial dystrophy, aphakic and pseudophakic bullous keratopathy) with dysfunctional endothelia as compared to both types of corneas (eye bank, keratoconus) with functional endothelial cells. There were no significant differences amongst the dysfunctional types or between the two functional types of corneal endothelial cells in respect to density of silver grains. Histochemical staining for ATPase showed less p-nitro-phenylphosphatase histochemical reaction product present on dysfunctional endothelial lateral membranes than in the functional cells.

Endothelial viral inclusions in Fuchs' corneal dystrophy

A case of Fuchs' corneal dystrophy is presented. The patient, a 70-year-old white woman, had bilateral decreasing vision, especially while reading and driving at night. Clinical features were characteristic of Fuchs' corneal dystrophy. Ultrastructural studies demonstrated findings in Descemet's membrane typical of those previously reported with numerous tactoids of fibrous long-spacing collagen in the posterior collagenous layer and in the guttata. In the endothelial cells were encapsulated ellipsoid viral particles, 400 nm long and 225 nm in diameter. They contained an outer and inner membrane with an electron-dense intervening region and a central dense core. Nucleocapsids were present in the endothelial cells and stromal keratocytes. The authors suggest that the pathogenesis of Fuchs' corneal dystrophy may be endothelial damage, and that in this case, the etiology is a viral infection.

Fuchs' corneal dystrophy. A clinicopathologic study of the variation in corneal edema

Corneal buttons from six patients with Fuchs' dystrophy had varying degrees of clinical edema measured in most cases by preoperative optical or ultrasonic pachymetry. These were sectioned in the operating room so that histologic correlations could be made. Histologically, marked thickening of Descemet's membrane and abnormal corneal endothelium corresponded to areas of severe clinical edema and were usually located in the central and paracentral regions. Descemet's membrane displayed multiple prominent guttata of varying size and shape, either facing the anterior chamber, or buried within multilaminar Descemet's membrane. In some corneas, aggregates of 10 nm fibrils were seen at the edges of guttata, corresponding to areas that stained for oxytalan fibrils. The endothelium was attenuated underlying the guttata. Clinical edema was not present unless accompanied by marked thickening of Descemet's membrane with multiple guttata and attenuation of corneal endothelium. The peripheral cornea was relatively clear clinically and showed minimal histologic changes.

Pump function of the human corneal endothelium. Effects of age and cornea guttata

The specific binding of tritiated ouabain to endothelial Na/K ATPase was used to quantitate the density of pump sites in the human corneal endothelium. Donor eyes, unsuitable for use in keratoplasty, were obtained from the Wisconsin Lions Eye Bank. The endothelium of each donor eye was examined using wide-field specular microscopy, and the specular micrographs were traced and digitized for the determination of cell density. Ouabain binding was measured in matched pairs of isolated endothelial sheets. A total of 26 pairs of donor eyes, ranging in age from 11 through 91 years, were studied. Twenty pairs, determined to have normal endothelia, were found to have a constant pump site density which was independent of donor age. Six donor pairs had moderate guttata; in this group pump site density was significantly increased. These results indicate that, although pump site density is normally constant in the human corneal endothelium, conditions which increase endothelial permeability, such as guttata, can cause a compensatory increase in pump site density and presumably pump function.

Color specular microscopy of disorders involving the corneal epithelium

Color specular microscopy, a noninvasive, in vivo microscopic technique, was utilized to study the corneal epithelium in 17 patients including eight with keratoconus, seven with bullous keratopathy, and two with Fuchs' corneal dystrophy. Color specular microscopy was also performed on rabbit corneas with experimental surgical trauma. Changes observed by specular microscopy in these diseased states correlated with alterations noted by light microscopy and scanning and transmission electron microscopy. Specular microscopy can provide detailed in vivo cellular morphology of the ocular surface, obviating the need for tissue biopsy. Thus, specular microscopy is a valuable diagnostic technique available for the clinician to monitor changes of the diseased ocular surface.

Is there an association between Fuchs' endothelial dystrophy and cardiovascular disease?

In order to investigate whether there is a clinical association between Fuchs' endothelial dystrophy of the cornea and atherosclerosis, the prevalence of cardiovascular disease was studied retrospectively in 27 patients with Fuchs' dystrophy and in 27 age- and sex-matched controls. The presence of cardiovascular disease was judged from a patient history of myocardial infarction, angina pectoris or heart insufficiency treated by medicaments and was found in 44% of the group with Fuchs' dystrophy and in 11% of the control group (P less than 0.05). The hypothesis is advanced that there may exist a common endothelial factor of possible significance for the development of corneal endothelial dystrophy, as well as the development of atherosclerotic lesions.

The ultrastructure of Descemet's membrane. III. Fuchs' dystrophy

The ultrastructure of Descemet's membrane was studied by transmission electron microscopy in corneal buttons removed from 11 phakic eyes with Fuchs' dystrophy. Abnormalities in Descemet's membrane consistent with abnormal endothelial function early in life (prior to age 20 years) were present in all corneas. Thus, despite the relatively late clinical onset of Fuch's dystrophy, endothelial abnormalities are present quite early in life in this disease. An abnormal fibrillar layer was thicker in those corneas with greater stromal and epithelial edema, possibly indicating that this layer is formed mainly during periods of endothelial decompensation.

A specular microscopic study of families with endothelial dystrophy

A prospective study of 12 families in which the proband had Fuchs's dystrophy was undertaken. Forty-four relatives were examined with the clinical specular microscope. Nine relatives, all women over 40 years of age, were affected. The mean endothelial cell density for unaffected relatives was 2889 cells/mm2 in the right eye and 2923 cells/mm2 in the left eye. Variability in endothelial cell size was not present in unaffected relatives but was present in those relatives with cornea guttata. Endothelial cell density decreased with age. The mean corneal thickness for unaffected and affected relatives was 0.51 mm and 0.53 mm, respectively. Unaffected relatives were compared with a control group with respect to endothelial cell density and corneal thickness. No significant difference was found between the 2 groups. In this study the clinical specular microscope failed to differentiate between controls and relatives of patients with Fuchs's dystrophy who at the time of examination did not have endothelial dystrophy. The instrument, therefore, could not be used to identify endothelial characteristics not visible with the slit-lamp which might be the forerunner of endothelial dystrophy.

Endothelial function in patients with cornea guttata

Measurements of corneal thickness, endothelial cell size, endothelial permeability to fluorescein, and intraocular pressure were made in two groups of human subjects: 21 persons with cornea guttata (early Fuchs dystrophy without epithelial edema) and 17 persons age- and sex-matched but with normal corneas. Statistically significant differences were found between the two groups in all four measured variables. The two groups did not differ with respect to the variability in endothelial cell sizes. There were statistically significant positive correlations between endothelial permeability to fluorescein, endothelial cell size, and corneal thickness. The endothelial pump rate was calculated for each group, and the difference was not statistically significant. Our results suggest that the earliest defect in Fuchs' dystrophy is solely a breakdown in barrier function and thus increased permeability, resulting in a thicker cornea.