Denovo development of corneal guttae and Fuchs' dystrophy in corneal grafts

PURPOSE

To describe two cases of de novo development of corneal guttae and Fuchs' dystrophy in donor tissue following penetrating keratoplasty (PK) for unrelated conditions.

METHODS

Two patients underwent PK for keratoconus and a disciform scar secondary to herpes simplex virus. They were followed clinically for a period of 16 and 11 years, respectively. Specular microscopy was used in one patient.

RESULTS

Corneal guttae were first noted 10 years and 4 years following transplantation in the first and second patient, respectively. In both cases, the corneal guttae gradually increased in number, involving the central and temporal portions of the corneal graft There were no corneal guttae present in the host corneal rim or contralateral cornea of either patient.

CONCLUSIONS

These cases provide evidence to suggest that some corneas may be genetically predetermined to develop corneal guttae and Fuchs' dystrophy many years before any changes can be clinically detected.

Corneal transplantation in young children with congenital hereditary endothelial dystrophy. Multicenter Pediatric Keratoplasty Study

PURPOSE

To describe the surgical success rate and visual results of penetrating keratoplasty in a series of young children with congenital hereditary endothelial dystrophy and to summarize the current literature on outcomes of keratoplasty for congenital hereditary endothelial dystrophy, with particular attention to the timing of surgery.

METHODS

The authors conducted a retrospective study of children aged 12 years and younger who underwent penetrating keratoplasty between 1975 and 1994 at four participating eye centers, and who were followed for at least 6 months postoperatively. For this report, 21 corneal transplants performed in 16 eyes of nine patients with congenital hereditary endothelial dystrophy were studied. Patients' median age at the time of first keratoplasty was 40 months (range, 3 months to 10 years).

RESULTS

During a mean follow-up period of over 70 months (range, 6 to 240 months), 11 (69%) of 16 eyes retained full graft clarity. The 2-year survival rate of first grafts was 71% (95% confidence interval, 47% to 95%). Postoperative visual acuity improvement of 1 or more Snellen lines was seen in five of 10 eyes in which the patients were old enough for accurate assessment of visual acuity; however, just four of these 10 eyes attained a visual acuity of 20/200 or better.

CONCLUSIONS

Penetrating keratoplasty for congenital hereditary endothelial dystrophy in children has a reasonable chance of surgical success when performed at a young age; however, the prognosis for improved visual acuity in children appears to be more guarded. Decisions on the timing of surgical intervention for congenital hereditary endothelial dystrophy should be made on a case-by-case basis. Although the threat of irreversible amblyopia in untreated eyes and good surgical success rates even among very young children argue for the consideration of relatively early surgical intervention in the most severely affected cases, there is evidence to support delaying surgery in some cases.

In vivo confocal microscopy of Fuchs' endothelial dystrophy

PURPOSE

The purpose of this study is to analyze in vivo confocal microscopic findings of corneas with Fuchs' endothelial dystrophy.

METHODS

Central corneas of 17 eyes of 11 patients aged 41-86 years were examined using in vivo scanning slit confocal microscopy after being diagnosed with Fuchs' endothelial dystrophy. The cellular structure of the corneas was analyzed morphologically and quantitatively and compared to control results from 22 healthy corneas.

RESULTS

Bullae were detected in the basal epithelial layer of one eye. Eight of 17 eyes (47%) exhibited an abnormal Bowman's layer: diffuse bright reflection and absence of nerves. Eleven eyes (65%) exhibited abnormal anterior stroma: lacunae and diffuse increased light reflection due to edema. In 12 eyes (71%), lacunae or dark bands 5-20 microm wide against increased background reflection were noted in the posterior stroma. Descemet's membrane was thickened in all eyes. Dark bands were detected in six eyes (35%). Guttae (137-1,231/mm2) 20-40 microm in diameter were found in every endothelial cell layer. The mean endothelial cell count was 1,202 +/- 850 (cells/mm2 +/- SD; range, 0-2,735). There was a positive correlation between endothelial cell counts obtained by specular microscopy and those obtained by confocal microscopy (r = 0.95).

CONCLUSION

In vivo confocal microscopic findings of Fuchs' endothelial dystrophy are described for the first time in a series of cases. Pathological changes in Fuchs' dystrophy were detected in all corneal layers, more frequently in the posterior layers. Endothelial cell counts obtained with confocal microscopy were statistically similar to those obtained with standard specular microscopy.

Corneal thickness in Fuchs' dystrophy with and without epithelial oedema

PURPOSE

To investigate whether the occurrence of epithelial oedema in Fuchs' endothelial dystrophy is associated with a particular corneal thickness or the extent of central corneal guttae.

METHODS

Sixty-seven patients, aged 52-90 years, presenting in our clinic with Fuchs' dystrophy were divided on the basis of the presence or absence of epithelial oedema as determined by slit lamp examination. After exclusion of extreme cases, the 56 cases without oedema were compared with the 10 cases with oedema with respect to corneal thickness, measured by ultrasound pachymetry and corneal guttae diameter, obtained from the slit lamp examination.

RESULTS

Mean corneal thickness was significantly higher (p = 0.002) in the oedematous group (mean = 0.682 mm) than in the group without epithelial oedema (mean = 0.624 mm). A corneal thickness greater than 0.650 mm was associated with a greater than 85% probability of oedema occurrence. Corneal guttae diameter did not differ significantly (p = 0.941) between the two groups and was not significantly correlated with corneal thickness (p = 0.269).

CONCLUSION

There is a demonstrable association between epithelial oedema and the measured thickness of the cornea.

The regularity of laser keratectomy depth in nonmechanical trephination for penetrating keratoplasty

BACKGROUND AND OBJECTIVES

To study the regularity of laser keratectomy depth in nonmechanical trephination for penetrating keratoplasty (PK) and to assess its implications on astigmatism and visual acuity (VA).

PATIENTS AND METHODS

In this retrospective clinicopathologic study, the authors enrolled 26 women and 32 men (mean age 54 +/- 20 years) with either keratoconus (n = 27) or Fuchs' dystrophy (n = 31), who underwent excimer laser (193 nm) trephination using a manually guided beam. Donor cornea trephination was performed using an artificial anterior chamber and either an automated rotation device (n = 27) or a manually guided beam (n = 31). The minimum residual corneal thickness (MRCT) and the random residual corneal thickness (RRCT), requiring division with scissors in excised patient buttons or corneoscleral donor rims, were assessed in a masked fashion using histologic sections. The postkeratoplasty keratometric net astigmatism, the subjective cylinder, and the VA were evaluated before and after suture removal.

RESULTS

In patients with keratoconus, the mean MRCT (13% +/- 14%) and RRCT (38% +/- 20%) were significantly higher than in the patients with Fuchs' dystrophy (7% +/- 11% and 26% +/- 15%, respectively) (P < .01). When an automated rotation device for trephination of the donor cornea was used, the mean MRCT (2% +/- 4%) and RRCT (14% +/- 11%) were significantly smaller than when a manually guided laser beam was employed (15% +/- 12% and 38% +/- 15%, respectively) (P < .001). After suture removal, the VA increased significantly with automated trephination (P = .04), but not with manually guided trephination of the donor cornea (P = .24). However, after a mean follow-up of 30 +/- 8 months, the differences in the mean keratometric astigmatism, refractive cylinder, and VA after automated trephination (3.0 D, 2.6 D, 20/29, respectively) compared with those after manually guided trephination of the donor cornea (4.3 D, 3.9 D, 20/33, respectively) did not reach statistical significance.

CONCLUSIONS

The regularity of donor trephination depth can be significantly improved by using an automated rotation device instead of a manually guided beam. Although residual postkeratoplasty astigmatism was not directly related to trephination depth, the improvement of the functional results after suture removal seems to be promoted by automated trephination.

Fuchs' corneal endothelial cells transduced with the human papilloma virus E6/E7 oncogenes

We sought to develop corneal endothelial cell cultures with extended lifespan from corneas with Fuchs' dystrophy. Descemet's-endothelial cell explants from histology confirmed recipient corneas of two patients with Fuchs' dystrophy were cultured. After a small number of corneal endothelial cells with irregular, endothelial morphology migrated from the explants onto the culture plate, the cells were transduced with a disabled retrovirus (pLXSN16E6/E7) coding for the human papilloma virus type 16 transforming oncoproteins E6 and E7. Expression of E6/E7 mRNA in the cell cultures with extended lifespan was monitored by RT-PCR. In vitro labeled cellular protein patterns of the Fuchs' E6/E7 cell cultures with extended lifespan were compared with those from normal human corneal endothelial E6/E7 cell cultures with extended lifespan using two-dimensional gel electrophoresis. Two endothelial cell cultures with extended lifespan were derived from Fuchs' corneas. The morphology of the Fuchs' cells expressing E6 and E7 was similar to that of normal corneal endothelial cells expressing E6 and E7. Surprisingly, the rate of proliferation of Fuchs'-derived cells was similar to that of normal endothelial cells transduced with E6/E7. Proliferation of each Fuchs' cell culture with extended lifespan continued for over 30 population doublings. There were limited quantitative differences in the two-dimensional gel electrophoretic protein patterns of the Fuchs'-derived and normal endothelial cell cultures with extended lifespan, respectively. Retroviral integration is dependent on cell proliferation. Thus, cells that migrated from the Fuchs' Descemet's explants were undergoing at least limited in vitro proliferation when the retroviral vector coding for E6/E7 integrated. Fuchs' corneal endothelial cells expressing E6 and E7 had similar proliferation, cellular morphology, and two-dimensional gel protein electrophoretic patterns to normal corneal endothelial cells expressing the same oncoproteins.

Keratan sulphate in the trabecular meshwork and cornea

PURPOSE

A study was made of the distribution of keratan sulphate in the human anterior chamber.

METHODS

The monoclonal antibody, 5-D-4, was used in immuno-electron microscopy to visualise keratan sulphate distribution in the anterior chamber of 16 normal eyes, 7 Fuchs' dystrophy corneas, and a macular dystrophy cornea.

RESULTS

Keratan sulphate was detected in normal human aqueous humour and also on the surface of trabecular cells in the uveal meshwork. Normal corneal stroma showed an increase in keratan sulphate labelling from anterior to posterior, with marked labelling in the posterior region of Descemet's membrane. The apical surface of the corneal endothelium labelled positively, but showed considerable variation in the level of labelling from cell to cell. The macular dystrophy cornea had the classic histopathological features of a type I case, including a highly abnormal Descemet's membrane. No keratan sulphate was detected in the macular dystrophy patient's corneal stroma or serum. The Fuchs' endothelial dystrophy corneas showed a normal distribution of keratan sulphate labelling in the stroma. The Fuchs' endothelial cells labelled for keratan sulphate but were highly abnormal in appearance, often exhibiting long filopodia and appearing to be actively migrating.

CONCLUSIONS

This work has shown that keratan sulphate has a much wider distribution than was previously believed. The detection of keratan sulphate on the trabecular and endothelial cell surfaces also suggests a possible role for this molecule in cell adhesion and/or migration.

Increased Corneal Scarring after Phototherapeutic Keratectomy in Fuchs' Corneal Dystrophy

PURPOSE

A 63-year-old female with Fuchs' endothelial corneal dystrophy, stromal edema and subepithelial scarring was inappropriately treated with phototherapeutic keratectomy, leading to a central focal circular corneal scar and decreased visual acuity that required penetrating keratoplasty.

METHOD

The host corneal button was bisected and fixed in 10% formaldehyde and in glutaraldehyde immediately after its removal.

RESULTS

Light microscopy demonstrated a central area of absent Bowman's layer with a thin layer of subepithelial fibrosis, stromal corneal edema, and thickened Descemet's membrane.

CONCLUSION

Correct estimation of differential ablation rates of tissue and shallow, repeated ablations followed by slit-lamp microscopy and/or videokeratography help prevent over-treatment.

Histologic Changes and Wound Healing Response Following 10-Pulse Noncontact Holmium:YAG Laser Thermal Keratoplasty

BACKGROUND

Noncontact holmium:YAG laser thermal keratoplasty (Ho:YAG LTK) is a promising new technology for correction of hyperopia and astigmatism. We studied the acute histologic changes and wound healing response following Ho:YAG LTK performed with treatment parameters encompassing those used in clinical studies.

METHODS

We performed 10-pulse noncontact Ho:YAG LTK on three human corneas 1 day before their removal at penetrating keratoplasty and on six New Zealand white rabbit corneas followed for up to 3 months. Tissues were studied with light and transmission electron microscopy and immunohistochemistry.

RESULTS

The amount of acute tissue injury increased according to the pulse radiant energy. In human corneas, changes in the irradiated zones included epithelial cell injury and death, loss of fine filamentous structure in Bowman's layer, disruption of stromal lamellae, and keratocyte injury and death. In the rabbit corneas, similar acute changes were noted. By 3 weeks, epithelial hyperplasia and stromal contraction were present. Wound healing in the rabbits included repair of the epithelial attachment complex, keratocyte activation, synthesis of type I collagen, partial restoration of stromal keratan sulfate and type VI collagen, and retrocorneal membrane formation.

CONCLUSIONS

Noncontact Ho:YAG LTK produces acute epithelial and stromal tissue changes and in rabbit corneas stimulates a brisk wound healing response.

Successful Phototherapeutic Keratectomy for Recurrent Erosions in Bullous Keratopathy

BACKGROUND

The treatment of patients with recurrent erosions due to bullous keratopathy is disappointing in cases when penetrating keratoplasty cannot be performed. A trial has been made to prevent recurrent erosions through the smoothing of the cornea with the excimer laser.

METHODS

Excimer laser phototherapeutic keratectomy (PTK) was performed after removal of the epithelium.

RESULTS

Sixteen patients (17 eyes) with recurrent erosions due to bullous keratopathy were treated. The mean follow-up period was 17.2 months (range: 3 to 32 months). All patients responded well to the treatment; their pain subsided after a few weeks. In four cases, a second treatment was necessary because areas with loose epithelium remained, which resulted in recurrent erosions. No complications have been seen so far.

CONCLUSION

Excimer laser PTK is an effective, easy to perform treatment of bullous keratopathy.

Primary cornea guttata in Japanese patients with cataract: specular microscopic observations

To evaluate the prevalence of primary cornea guttata (the first stage of Fuchs' dystrophy) in Japanese patients, we retrospectively examined specular photomicrographs of patients' cataracts. Primary cornea guttata in subjects without corneal inflammation was defined as dark areas, seen on specular microscopy, and irregular refractile dots, observed with slit-lamp microscopy. In 107 patients with cataract (211 eyes), primary cornea guttata was found in 4 women (7 eyes), aged 56 to 76 years. One eye of patient 4, who had a history of angle-closure glaucoma and laser iridotomy, had bullous keratopathy. We also examined 16 relatives (32 eyes) of these 4 affected patients (probands), and found 2 women (4 eyes) with primary cornea guttata. No hereditary influence was identified. We believe that the incidence of primary cornea guttata (Fuchs' dystrophy) in Japan is lower than that in North America.

The significance of anterior chamber depth in Fuchs' corneal dystrophy and cornea guttata

It is sometimes claimed that a relationship exists between Fuchs' dystrophy and angle closure glaucoma and that this is an indication for the simultaneous performance of keratoplasty and cataract extraction in patients with Fuchs' dystrophy. If such a relationship exists, then the anterior chamber depth in Fuchs' dystrophy should resemble that in angle closure glaucoma and a significant degree of cornea guttata might be expected to be common in angle closure glaucoma. In 88 patients with angle closure glaucoma we found that the anterior chamber depth was significantly shallower than in cornea guttata or Fuchs' dystrophy for acute (p < 0.001), chronic (p < 0.002) or incipient angle closure glaucoma (p < 0.001). Cornea guttata and Fuchs' dystrophy were very infrequent in these patients with angle closure, only two having cornea guttata and one Fuchs' dystrophy. These results do not support a relationship between angle closure glaucoma and Fuchs' dystrophy or cornea guttata and do not justify performing combined cataract surgery and keratoplasty in all cases of cornea guttata or Fuchs' dystrophy undergoing keratoplasty. Each case should be assessed on its merits and combined surgery should be reserved for patients shown to have a shallow anterior chamber or significant cataract.

Emergence of cornea guttata in donor tissue: a cause of late graft failure

Analysis of 321 failed full-thickness corneal transplant specimens submitted for histopathological examination over a 10-year period has identified 10 instances in which the defect appeared to have been caused by the development of cornea guttata in the donor tissue. The primary condition necessitating keratoplasty in 5 of the 10 patients was Fuchs' endothelial dystrophy but, given the limited capacity of corneal endothelium for regeneration, it is considered unlikely that the defect in the grafts represented a recurrence. In 7 of 8 cases for which the duration of graft survival was known the endothelial disorder presented as a long-term event and it is assumed that the condition was not present at the time of the keratoplasty. The rare emergence of Fuchs' dystrophy in donor transplant tissue should be added to the potential causes of late graft failure.

Fuchs' endothelial dystrophy of the cornea

Fuchs' endothelial dystrophy of the cornea is a significant cause of corneal blindness in the United States. The disease is characterized by a slow, continuous loss of morphologically and physiologically altered endothelial cells, eventually leading to corneal edema. The endothelial cells synthesize a thickened Descemet's membrane with focal excrescences of altered basement membrane material (guttae). This review details the epidemiological, clinical, and laboratory data that have accumulated on Fuchs' dystrophy. Several hypotheses regarding the pathogenesis of Fuchs' dystrophy are discussed, including the possible influences of aberrant embryogenesis, hormones, and injury on the development of the disease. The current state of medical and surgical management is summarized, along with the future prospects for treatment.

Corneal endothelial involvement in pseudoexfoliation syndrome

Information on corneal manifestation in pseudoexfoliation syndrome is restricted to specular microscopic studies. We investigated morphologic changes of the posterior cornea of two corneal buttons with Fuchs' endothelial dystrophy obtained at penetrating keratoplasty and of one enucleated glaucomatous eye from three patients with ocular pseudoexfoliation syndrome. By transmission electron microscopy, large clumps of typical pseudoexfoliation material were found adhering to the corneal endothelium and masses of pseudoexfoliation material were incorporated into the posterior Descemet's membrane. In the affected areas, the endothelial layer appeared irregular and discontinuous, with loosely adherent, degenerating cells producing pseudoexfoliation fibers and fibroblastic cells spreading to cover denuded Descemet's membrane. The present findings indicate that the pseudoexfoliation material is initially formed by degenerative endothelial cells and that it becomes subsequently buried by overgrowing cells. The corneal endothelial involvement may potentiate complications of cataract surgery and open angle glaucoma in patients with pseudoexfoliation syndrome.

Growth of human corneal endothelium on altered Descemet's membrane

To determine whether Descemet's membrane (DM), which is altered by disease, interferes with endothelial cell growth, healthy human corneal endothelial cells were seeded onto DM from normal corneas and diseased corneal buttons from patients with Fuchs' endothelial dystrophy and pseudophakic bullous keratopathy (PBK). DM was first peeled off the corneal specimens and the endothelial cells removed by trypsinization. A suspension of first-passage corneal endothelial cells (2,000 cells/microliters; obtained from donor eye bank eyes and grown in Dulbecco's minimal essential medium with 10% fetal bovine serum and 1.5% chondroitin sulfate) were seeded on DM. Epidermal growth factor (10 ng/ml) and insulin (1 U/ml) were added to the medium after seeding cells on the DM. The cells attached and flattened within 1 hour and reached confluency in 1 week on normal DM. Cells grown on DM from corneas of patients with Fuchs' endothelial dystrophy also flattened and grew to confluency in 1 week. Cells grown on DM from corneas of patients with PBK did not grow to confluency. Further studies with bovine and rabbit corneal endothelial cells showed similar growth pattern to human cells. These data indicate that DM from corneas of patients with Fuchs' dystrophy does not interfere with the growth of corneal endothelial cells but that DM from corneas of patients with PBK does interfere with cell growth.

[The pathologically changed Descemet membrane. Cultivation of human corneal endothelium on transformed membrane]

Corneal endothelial diseases are connected with structural and biochemical changes of Descemet's membrane (DM). Little is known about the possible effects of these changed basement membranes. In the present study we investigated the influence of changed DM on endothelium. Human corneal endothelial cells were cultured on DM of healthy corneas as well as corneas with Fuchs' endothelial dystrophy or bullous keratopathy, and cell growth and morphology were compared. On healthy DM, cells formed a confluent monolayer within 4 days. Cells cultured on Fuchs' DM showed a similar pattern. The polygonal cell pattern was interrupted merely in the area of the guttae, which were covered by cell processes alone. Culturing cells proved to be difficult on DM from corneas with bullous keratopathy. Even though the cells attached to the DM, they did not spread but became spindle shaped and rarely formed intercellular contacts. Even after 7 days no confluent monolayer was established. These results indicate that some though not all pathological DM changes interfere with cell growth.

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

Images

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.