Uso de voriconazol tópico en queratitis por alternaria / Use of topical voriconazole in alternatia keratitis

Caso clínico: Hombre de 38 años remitido de otro centro por presentar queratitis fúngica por Alternaria 25 días después de realizarle una queratoplastia penetrante postraumática en ojo derecho. Se instaura tratamiento con voriconazol tópico y oral con buena evolución posterior. Discusión: Las queratitis fúngicas por Alternaria son poco frecuentes. Su tratamiento es difícil porque la evolución clínica no se correlaciona con la susceptibilidad in vitro del hongo. Producen cuadros clínicos que requieren un rápido diagnóstico y tratamiento, para evitar la pérdida de visión. La combinación de voriconazol tópico y sistémico puede ser una buena alternativa en caso de hongos resistentes al tratamiento convencional

Clinical case: A 38-year-old man with fungal Alternaria keratitis was referred from another hospital 25 days after post-traumatic penetrating keratoplastia surgery on his right eye. We commenced treatment with topical voriconazole and the condition resolved. Discussion: Fungal Alternaria keratitis is rare, and treatment is difficult because the clinical response does not correlate well with the antibiotic in vitro sensitivity of the fungus. Clinical cases need to be diagnosed and treated quickly if visual loss is to be avoided. The combination of topical and systemic voriconazole has been shown to be an effective treatment for this condition (Arch Soc Esp Oftalmol 2008; 83: 493-496)

Graft failure: II. Ocular surface complications.

Risk factors for corneal transplantation failure include both immunologic factors, such as graft rejection, corneal neovascularization, and peripheral anterior synechiae, as well as non-immunologic factors, such as ocular surface disorders (OSD) and glaucoma. This review highlights the necessity of having healthy ocular surface epithelia, tears, and eyelids. It presents different types of OSD, their underlying pathology, and their impact on native cornea and corneal grafts. In addition, a range of proposed donor and surgical factors influencing surface integrity following corneal transplant are addressed. Current medical and surgical research, both pre- and post-operative that promise to further improve the outcome of corneal grafts in the context of OSD are discussed.

In vivo confocal microscopy of corneal grafts shortly after penetrating keratoplasty.

PURPOSE: To describe the microstructural status of corneal grafts shortly after penetrating keratoplasty (PK) and to evaluate the efficacy and safety of confocal microscopy in examining corneal grafts at that time. METHODS: A confocal microscope with a 40 x front lens was used to examine corneal grafts in 32 patients (32 eyes) 4 days after PK. Images were analyzed, and endothelial cell density counts were compared with presurgical, eye bank values determined by specular microscopy. RESULTS: Microstructural alterations of the graft included epithelial and stromal edema, epithelial degeneration in both superficial and basal cell layers, dark stromal striae, activated keratocytes, and needle-like structures in the stroma. Descemet membrane folds were visible in 31 of 32 grafts; in 1 graft, the dense stromal edema did not allow imaging of posterior layers. Stromal nerve fibers were imaged in 28 grafts (88%). Endothelial cell density ranged from 1666 to 2548 cells/mm2 (mean+/-SD, 2125+/-283 cells/mm2); perioperative endothelial cell density loss varied from 0% to 29% (mean, 12%). No adverse reactions or signs of worsening of clinical condition were observed after the examination. CONCLUSIONS: White light scanning slit confocal microscopy permits imaging of a graft's microstructure (including epithelium and stromal layers), as well as calculation of endothelium cell density, as soon as 4 days after PK. The most frequently observed morphologic alterations of corneal grafts shortly after PK include epithelial and stromal edema, epithelial degeneration, stromal striae, and Descemet membrane folds. Stromal nerves can still be seen in the graft 4 days after PK.

Keratocyte density and recovery of subbasal nerves after penetrating keratoplasty and in late endothelial failure.

OBJECTIVE: To determine central keratocyte and subbasal nerve densities in clear and failed grafts after penetrating keratoplasty. METHODS: Clear grafts and grafts with late endothelial failure (LEF) were examined using confocal microscopy 1 to 31 years after penetrating keratoplasty. Keratocyte density, number of keratocytes in a full-thickness column of stroma, and subbasal nerve density were determined from images. Comparisons were made with normal corneas. RESULTS: The mean +/- SD keratocyte density in clear grafts (22 101 +/- 3799 cells/mm(3)) was lower than that in normal corneas (26 610 +/- 3683 cells/mm(3); P < .001) but did not differ from that in grafts with LEF (21 268 +/- 3298 cells/mm(3); P = .47). The mean +/- SD number of keratocytes in clear grafts (10 325 +/- 1708 cells) was lower than that in normal corneas (11 466 +/- 1503 cells; P < .001) but did not differ from that in grafts with LEF (10 778 +/- 1760 cells; P = .39). Median subbasal nerve density in clear grafts (150 microm/mm(2)) was lower than that in normal corneas (7025 microm/mm(2); P < .001), and nerve recovery correlated with time after surgery (r = 0.36; P < .001). CONCLUSIONS: Keratocyte density and number are decreased in penetrating grafts compared with normal corneas. Subbasal nerve density does not recover to normal through 3 decades.

Graft central thickness measurement by rotating Scheimpflug camera and ultrasound pachymetry after penetrating keratoplasty.

PURPOSE: To assess agreement between rotating Scheimpflug camera and ultrasound pachymetry in measuring graft central thickness, and compare reproducibility/repeatability of these methods in corneal grafts and normal corneas. DESIGN: Experimental study. PARTICIPANTS: Sixty-five patients with corneal grafts after penetrating keratoplasty and 20 controls with normal corneas (1 eye per patient). METHODS: In 45 eyes with clear grafts after penetrating keratoplasty, graft central thickness measurements were compared between the 2 methods (examiner 1). In another 20 eyes with clear grafts after penetrating keratoplasty and in 20 normal corneas, 2 independent examiners (1 and 2) each employed both methods in a first session to assess interexaminer reproducibility; measurements were then repeated by examiner 1 alone in a second session, and differences with his first session measurements used to assess intraexaminer repeatability. Paired t test, intraclass correlation coefficient (ICC) and 95% limits of agreement (95% LoA) were calculated to assess differences, correlation, and variability of methods, examiners, and first-second measurements. MAIN OUTCOME MEASURES: Graft central thickness measurements by 2 methods. Difference of measurements by 2 examiners; and difference of first-second measurements by 1 examiner, in corneal grafts and normal corneas with both methods. RESULTS: Mean graft central thickness measurement was 556.9+/-41.8 microm with the rotating Scheimpflug camera and 561.8+/-40.8 with ultrasound pachymetry (P = 0.012). There was a significant linear correlation in graft central thickness measurement between the 2 methods (r = 0.93; P<0.001) and 95% LoAs were -34 to +23.4 microm. Interexaminer and intraexaminer correlations were high with both methods: ICCs were > or = 0.94 in corneal grafts and > or = 0.98 in normal corneas. Interexaminer and intraexaminer variability was slightly higher with the rotating Scheimpflug camera than with ultrasound pachymetry, and in corneal grafts than in normal corneas. CONCLUSIONS: Measurements of graft central thickness with the rotating Scheimpflug camera, although slightly lower, were comparable to those with ultrasound pachymetry. The reproducibility and repeatability of these methods in corneal grafts are only slightly lower than in normal corneas.

Laminins in normal, keratoconus, bullous keratopathy and scarred human corneas.

The laminin composition (LMalpha1-alpha5, beta1-beta3, gamma1 and gamma2 chains) of normal corneas and corneal buttons from keratoconus, bullous keratopathy (BKP), Fuchs' dystrophy + BKP, Fuchs' dystrophy without BKP and scar after deep lamellar keratoplasty (DLKP) was investigated with immunohistochemistry. The epithelial basement membranes (BMs) of both normal and diseased corneas contained LMalpha3, alpha5, beta1, beta3, gamma1 and gamma2 chains. The epithelial BM morphology was altered in the different diseases. Scarring was associated with irregular BM and ectopic stromal localization of different laminin chains. The Descemet's membrane (DM) contained LMalpha5, beta1 and gamma1 chains in all cases and additionally LMbeta3 and gamma2 chains in the majority of keratoconus corneas. The interface in the DLKP cornea had patches of LMalpha3, alpha4, alpha5, beta1 and beta2 chains, and an extra BM-like structure under the Bowman's membrane. These results suggest that laminin chains participate in the process of corneal scarring and in the pathogenesis of some corneal diseases. The novel finding of LMalpha3, beta3 and gamma2 in the DM of keratoconus buttons indicates that this membrane is also involved in the disease and that some cases of keratoconus may have a congenital origin, without normal downregulation of the LMbeta3 chain.

Recurrence of keratoconus in two corneal grafts after penetrating keratoplasty.

PURPOSE: To report the recurrence of postkeratoplasty keratoconus in 2 corneal grafts harvested from the same donor. DESIGN: Interventional case reports. METHODS: A 21-year-old-man with advanced keratoconus in his right eye and a 28-year-old-woman with corneal leucoma in her right eye underwent penetrating keratoplasty with 2 grafts coming from the same donor. Approximately 1.5 years after grafting, corneal irregularity and astigmatism caused visual acuities of the patients to decrease to counting fingers. Clinical findings and corneal topography suggested the recurrence of keratoconus. A repeat keratoplasty was performed in both patients. RESULTS: Histopathology of the excised corneal grafts was consistent with keratoconus and confirmed the preoperative diagnosis. CONCLUSIONS: Recurrence of keratoconus in a patient who had no preexisting keratoconus and in 2 corneal grafts coming from the same donor suggested transmission of the disorder from the donor instead of true recurrence.

Comparison of optical low-coherence reflectometry and ultrasound pachymetry in measuring corneal graft thickness.

PURPOSE: To compare optical low-coherence reflectometry (OLCR) and ultrasound pachymetry in measuring corneal graft thickness in patients after keratoplasty. METHODS: We retrospectively measured the central graft thickness in 41 eyes of 41 patients with the OLCR pachymeter (Haag Streit, Koeniz, Switzerland) and the SP-2000 contact ultrasound pachymeter (Tomey, Nagoya, Japan). Five separate measurements were performed on each eye with both methods. Mean, SD, repeatability, and coefficient of variation of measurements were calculated, and the correlation between the 2 methods was studied with Spearman regression. RESULTS: Mean central graft thickness was 546 +/- 51 (SD) microm with the contact ultrasound pachymeter and 546 +/- 47 microm with the OLCR pachymeter. The correlation between both methods was strong (rs = 0.96). No significant differences in mean SD of measurements were observed between OLCR pachymetry (mean SD = 4.66 microm) and contact ultrasound pachymetry (mean SD = 4.88 microm). The repeatability of both methods was comparable (P = 0.06) and high (the average coefficient of variation of the central corneal graft thickness was 0.9% with both pachymeters). The postoperative time did not affect the correlation between both pachymeters (P > 0.05). CONCLUSIONS: Central corneal graft thickness values obtained with the OLCR pachymeter were similar to those obtained with a contact ultrasound pachymeter. In some cases of lamellar keratoplasty, the corneal refractive index could change at the interface level that could affect OLCR measurements.

A longitudinal case series investigating cellular changes to the transplanted cornea using confocal microscopy.

PURPOSE: To perform a longitudinal evaluation of subjects who had undergone penetrating keratoplasty, using slit scanning confocal microscopy. METHODS: In vivo confocal microscopy was used to evaluate the central cornea of four subjects who had recently undergone penetrating keratoplasty. Subjects were examined on four occasions over a 12-month period after surgery. Quantitative and qualitative aspects of corneal morphology were compared against data from normal control subjects. RESULTS: The epithelium varied in appearance between subjects and took at least 12 months to return to a similar arrangement to that seen in normal eyes. Bowman's layer was viewed as an acellular layer immediately after surgery with no evidence of nerve fibres, although nerve components were apparent 12 months after surgery. Stromal nerves were not visible immediately after surgery. One year following penetrating keratoplasty there was evidence of thin nerves running a straight course through the central stroma. Keratocyte density in the anterior and posterior stroma was lower in the transplanted cornea but appeared to remain constant over a period of 1 year. Activated keratocytes were seen in the anterior stroma of all subjects; they appeared to be responsible for significant levels of corneal haze. The time period within which this keratocyte activation occurred varied between individuals. Endothelial cell density decreased at an accelerated rate over the 12-month period. CONCLUSIONS: Confocal microscopy allows cellular changes to be monitored in vivo following penetrating keratoplasty and may assist clinicians in understanding postoperative recovery.

Endotoxin in storage medium of human corneal grafts and clinical course after penetrating normal-risk keratoplasty.

PURPOSE: It is well known that endotoxins in storage medium may stimulate cytokine production and expression of adhesion molecules as well as endothelial damage in human corneal grafts. It has been supposed that endotoxin exposure of corneal grafts may, therefore, cause immune reactions and lead to reduced endothelial cell count after penetrating keratoplasty. It was the purpose of this prospective study to evaluate if this hypothesis is true. METHODS: A consecutive series of 274 samples of sterile organ culture storage medium from 274 human corneal grafts was collected between August 1998 and February 1999 and tested for endotoxin using Limulus amebocyte-lysate assay (LAL) after 7 days of organ culture. Threshold endotoxin level was set at 1.0 U/ml. A total of 161 grafts were transplanted and 113 were discarded. Within the 161 corneas transplanted, 62 were grafted to normal-risk patients and 99 to high-risk patients. Only normal-risk keratoplasty patients were included in the study and followed for at least 10 months. Immune reactions, graft failures, and postoperative endothelial cell counts were recorded. RESULTS: The mean endotoxin level in organ culture medium of all transplanted grafts was 1.07+/-2.96. Mean endotoxin level in organ culture medium of discarded grafts was 1.68+/-5.76, with 71 samples being below and 42 above the threshold of 1.0 U/ml called endotoxin-negative and endotoxin-positive, respectively. In all 36 culture medium samples from the 62 grafts transplanted to the group of normal-risk keratoplasty patients were endotoxin-negative and 26 endotoxin-positive. An influence of endotoxin levels on incidence of immune reactions, graft failure, and postoperative endothelial cell counts could not be revealed in patients with normal-risk keratoplasty. CONCLUSION: Low endotoxin levels in storage medium neither seem to promote immune reactions nor to contribute to postoperative chronic endothelial cell loss in normal-risk keratoplasty patients.

Preliminary findings in corneal allograft rejection in patients with keratoconus.

PURPOSE: Classically, corneal allograft rejection is thought to be a T(H)1-mediated phenomenon. However, T(H)2-mediated allograft rejection has been reported in other transplanted organ systems, including the heart and kidney. We previously reported a form of T(H)2-mediated corneal allograft rejection in a murine model with a T(H)2 immune bias. In this study we sought to determine if there was any evidence for this form of corneal allograft rejection in humans. DESIGN: Experimental study with an interventional case series. METHODS: The clinical records of all keratoconus patients undergoing penetrating keratoplasty at the University of Texas, Southwestern Medical Center from 1994 to 1999 were reviewed. Careful attention was paid to a clinical history of atopy. Atopic patients were selected, because these patients have been shown to have a "T(H)2 immune bias." The corneal graft rejection rate in these patients and the number of repeat corneal transplants performed was determined. The experimental group consisted of patients with a clinical history of atopy and keratoconus who had at least one repeat penetrating keratoplasty for an immunologically rejected corneal transplant. Any patient with evidence of primary allograft failure was excluded from this study. Tissue specimens from these patients were embedded in paraffin, serially sectioned, stained with Giemsa stains, and examined histologically. The control group consisted of patients without a clinical history of allergy (and therefore no T(H)2 immune bias) who underwent corneal transplantation for Fuch corneal endothelial dystrophy, or aphakic/pseudophakic bullous keratopathy. Failed grafts from these control patients were also paraffin embedded, serially sectioned, stained, and examined histologically. The human experimental and control corneal specimens were compared with data obtained in a murine model of T(H)2-mediated corneal allograft rejection. Briefly, full-thickness penetrating C57BL/6ByJ corneal allografts were transplanted onto Balb/cByJ and Balb/c-IFN-gamma(tm1Ts) (Balb/c-IFN-gamma knockout) mice. Additionally, full-thickness Balb/cByJ corneal allografts were transplanted onto C57BL/6ByJ and C57BL/6ByJ-IFN-gamma(tm1Ts) mice. Corneal allograft rejection rates and mean rejection times were calculated and compared between wild-type and interferon gamma (IFN-gamma) knockout hosts. The rejected allografts were examined histologically by the same methods used in the human tissue. RESULTS: There were 84 penetrating keratoplasties performed from 1994 to 1999 for keratoconus. Seven of these 84 patients rejected their corneal grafts. Of the 7 patients who rejected their corneal allografts, 4 had repeat penetrating keratoplasty. Of these 4 repeat corneal allografts, 3 showed eosinophilia when compared with rejected grafts in control patients. Atopic keratoconus patients had a mixed inflammatory cellular infiltrate in the rejected corneal tissue specimen with a significantly greater density of eosinophils (P =.001) compared with patients who did not have a pre-existing T(H)2 bias. The inflammatory infiltrate in these patients without a T(H)2 immune bias was mononuclear. In the murine model, corneal allograft rejection did occur in the absence of IFN-gamma, a critical T(H)1 cytokine in both fully allogeneic donor-host combinations. Histologically, rejection in these ("T(H)2 mice") was characterized by a predominant eosinophilic infiltrate in the rejected graft bed when compared with wild-type animals ("T(H)1 mice") that had a predominantly mononuclear infiltrate in the rejected corneal graft bed. CONCLUSIONS: Preliminary findings show that corneal allograft rejection in patients with a pre-existing T(H)2 phenotype is similar to what is seen in the murine model of T(H)2-mediated corneal allograft rejection. Based on this small sample, it appears that eosinophils may play a role in corneal allograft rejection in this group of patients. However, further study is necessary to determine the importance of these cells in allograft rejection.

Histopathological correlation of corneal diseases with optical coherence tomography.

PURPOSE: To correlate the cross-sectional images of corneal diseases obtained by optical coherence tomography (OCT) with light microscopy (LM) to determine the corneal components represented in OCT images. METHODS: In a prospective comparative tissue study clinicopathological correlations of six patients with pseudophakic bullous keratopathy ( n=3), advanced keratoconus ( n=1), persistent epithelial defect with corneal thinning ( n=1), and retrocorneal membrane ( n=1) were included. Immediately before a planned penetrating keratoplasty (PKP) noncontact slitlamp-adapted OCT of the cornea was performed. After PKP and following standard histological processing the specimens were examined under LM to compare qualitatively the morphology, and quantitatively the morphometry at selected corneal locations. RESULTS: The cross-sectional optical-reflectivity profiles enabled the reproducible morphological evaluation of the corneal structures and changes. Layers of relative high reflectivity corresponded to the anterior corneal surface and internal stromal layers. In contrast, the deeper corneal epithelial layer demonstrated relative low reflectivity by OCT. An increase in light reflectivity corresponded to corneal scarring, irregularities of the corneal lamellae, and deposition of basal membrane material. Low signal intensity was particularly due to fluid accumulations and shadowing. The most prominent changes were caused by corneal scars or edematous tissue. The morphometric analysis with OCT revealed, in this study, thickness measurements ranging from 31 to 902 micro m. Although the mean OCT thickness values were up to 9% ( P=0.014) higher than those derived from LM, there was a significant positive correlation (r=0.94; P<0.001) between corneal OCT and the light-microscopic measurements. CONCLUSION: Noncontact slitlamp-adapted corneal OCT revealed a good correlation with histological sections. The differences noted were partly related to shrinking processes during preparation. Thus, with certain limitations, OCT allows a non-invasive optical biopsy of pathological structures in corneal diseases.

[Chronic endothelial cell loss of the graft after penetrating keratoplasty: influence of endothelial cell migration from graft to host]. / Chronischer Endothelzellverlust des Transplantats nach perforierender Keratoplastik: Einfluss der Migration von Endothelzellen vom Transplantat zur Wirtshornhaut.

BACKGROUND: Chronic endothelial cell loss of the graft is common after penetrating keratoplasty. Some kind of subclinical immunological reaction that is not visible at the slitlamp has been suspected as main cause for this phenomenon. Furthermore, migration of graft endothelial cells towards the host cornea has been discussed to add to this loss in special cases. In this study, 3 homogenous patient groups with similar risk of immunological reactions were examined. Main difference between these groups was the potential of graft endothelial cells to migrate towards the host cornea. PATIENTS AND METHODS: Patients with keratoconus without cataract surgery (group I with little migration potential, n = 273), patients with Fuchs endothelial dystrophy without/with cataract surgery (groups IIa/IIb with moderate migration potential, n = 89/n = 165) and patients with bullous keratopathy after cataract surgery (group III with potentially large migration tendency, n = 188) were included in the study. All patients had a first keratoplasty. Patients with glaucoma or further intraocular procedures after keratoplasty were excluded from the study. Clear graft survival and ratio of grafts without immune reactions were estimated according to Kaplan and Meier. Endothelial analysis concerned only patients without immune reactions and with at least 3 postoperative endothelial cell density values of the graft center (76 patients in I, 18 patients in IIa, 41 patients in IIb and 23 patients in III). RESULTS: Mean relative loss of endothelial cells per year was 14.0 +/- 19.0 % in group I, 17.0 +/- 19.1 % in group IIa, 20.8 +/- 18.2 % in group IIb and 29.4 +/- 17.6 % in group III (ANOVA, p < 0.01). Five years postoperatively in group I 99 %, in group IIa 98 %, in group IIb 93 % and in group III 69 % of the grafts were centrally clear (log rank test, p < 0.001). In the same period in group I 88 %, in group IIa 86 %, in group IIb 83 % and in group III 81 % of the grafts were free of immune reactions (log rank test, p < 0.05). Reasons for irreversible graft failure were immune reactions (0 in group I; 0 in group IIa; 1 in group IIb; 9 in group III, ), surface disorders (1 in group I; 0 in IIa; 1 in group IIb; 3 in group III) and endothelial failure (0 in group I; 1 in group IIa; 5 in group IIb; 6 in group III) (chi square test, p < 0.01). CONCLUSIONS: In patients with bullous keratopathy endothelial cell loss via migration seems to add significantly to the general chronic loss which is suspected to be immunological. Peripheral migration of endothelial cells, therefore, most probably contributes to limited prognosis of patients with bullous keratopathy in terms of clear graft survival. In consequence, corneal grafts for bullous keratopathy should be as large as immunologically tolerable, and endothelial cell density should be as high as possible in order to counteract this special endothelial loss factor.

[Epithelial damage of corneal grafts after prolonged storage in dextran-containing organ culture medium - a prospective study]. / Hornhautepithelschädigung bei langer Transplantatverweildauer in dextranhaltigem Organkulturmedium - eine prospektive Studie.

BACKGROUND: High-molecular dextran added to organ culture medium is used for deswelling of corneal grafts before surgery. As we had the impression to have more often epithelial desquamation if storage time in dextran-containing medium was longer than 1 day, we investigated this problem in a pilot study. METHODS: We examined prospectively the effect of the storage period on the graft epithelium one day after penetrating keratoplasty in 137 corneal grafts which were stored in dextran-containing storage medium (dextran T500 6 %). 88 corneal grafts were stored for 1 - 2 days (12 - 48 hours) and 49 corneal grafts were stored for 3 - 4 days (60 - 96 hours). Before deswelling, all 137 grafts had been stored 10 - 14 days in dextran-free organ culture medium. Postoperative epithelial defects observed 1 day after surgery were classified as margin and central erosions of the graft. RESULTS: With a storage period in dextran-containing organ culture medium of 1 - 2 days statistically significantly less epithelial defects were observed in comparison to a longer storage period of 3 - 4 days (33 % vs. 57 %, p = 0,005). We found a statistically high significant correlation between storage time in dextran-containing organ culture medium and central erosions (p = 0,001), whereas margin erosions were observed after 1 - 2 days as well as after 3-4 days (p = 0,2). CONCLUSION: Our data show that early postoperative epithelial stability of corneal grafts depends on the storage period in dextran-containing organ culture medium.

Corneal endothelial cell changes twenty years after penetrating keratoplasty.

PURPOSE: To evaluate retrospectively the corneal endothelium in 15 eyes which showed clear cornea for 20 years or longer after penetrating keratoplasty. METHODS: The corneal endothelium was investigated in 15 eyes. The causative lesion had been keratoconus in 10 eyes and herpetic keratitis in 5 eyes. At the time of surgery, the patients were aged from 6 to 45 years, average 25.3 +/- 10.4 years. The endothelial cell density was measured 10 and 20 years after surgery by specular microscope. The relation between the rate of endothelial cell density loss and postoperative graft rejection, final visual acuity, causative corneal lesion, age of the patient, and age of the donor was evaluated. RESULTS: The endothelial cell population per mm(2) averaged 998 +/- 343 ten years after surgery and 852 +/- 245 twenty years after surgery. The rate of endothelial cell density loss thus averaged 12.1% +/- 16.3% during the last 10 years. This rate was independent of postoperative graft rejection, final visual acuity, causative corneal lesion, age of the patient, or age of the donor. CONCLUSIONS: The corneal endothelial cells become stabilized 10 years after surgery in cases where the grafts remain transparent 20 years after surgery.

Keratocyte activation and apoptosis in transplanted human corneas in a xenograft model.

PURPOSE: To study keratocyte activation and cellular apoptosis in transplanted human corneas during the early postoperative period. METHODS: Ten human donor corneas preserved for 6 days at 4 degrees C were transplanted into the eyes of 10 adult cats. After confocal and specular microscopy in vivo 1 week after keratoplasty, the cats were killed, and the fixed corneas were examined by TUNEL assay and by scanning (SEM) and transmission electron microscopy (TEM). RESULTS: Abnormal keratocytes, in which portions of cell bodies and processes as well as nuclei were visible, were present in all corneas and occupied the anterior 16 to 562 microm of the stroma. By TEM in the same corneas, these abnormalities represented keratocytes that were activated to a repair phenotype. Only 0% to 1% of all corneal cells were apoptotic by TUNEL assay, except for the donor keratocytes near the wound, where 7% were apoptotic. The midstromal keratocyte density was decreased at 13,936 +/- 5,910 cells/mm(3) (mean +/- SD), and the endothelial cell density was 2,298 +/- 688 cells/mm(2), representing an endothelial cell loss of 7% +/- 16%. CONCLUSIONS: Substantial keratocyte activation and low levels of cellular apoptosis occur 1 week after human corneal transplantation. The human-to-cat xenograft model of corneal transplantation demonstrated endothelial cell loss and other clinical findings similar to human allografts. The model will be useful for preclinical testing of new methods of long-term corneal preservation and of donor endothelial cell augmentation, as well as the study of human corneal wound healing and keratocyte replacement during the early postoperative period.

Effect of alloantibodies on corneal allograft survival.

PURPOSE: The precise role of antibodies in corneal transplantation is ambiguous, with evidence to support as well as repudiate their involvement in graft rejection. Accordingly, this study was undertaken to investigate the direct contribution of donor-specific antibodies to corneal graft rejection. METHODS: Serum samples from CB6F1 rejecters of orthotopically grafted C3H/Hej corneas were tested by ELISA for elevated levels of donor-specific alloantibody. Orthotopic corneal allograft rejection was also examined in B-cell-deficient mice. In a prospective study, naïve BALB/c T-cell-deficient nude mice and complement-depleted nude mice were passively infused with immune donor-specific serum and grafted with fully allogeneic C57BL/6J corneas. The incidence and speed of graft rejection were observed in each case. The susceptibility of corneal cells to antibody-mediated lysis was tested in vitro. RESULTS: Seventy percent of the CB6F1 hosts that rejected the C3H/Hej corneal allografts possessed significantly elevated levels of alloantibody in serum. Although BALB/c corneal allografts were rejected by B-cell-deficient mice at the same incidence as wild-type control mice, their mean survival time (MST) was significantly longer than that of their wild-type counterparts. Serum of BALB/c mice immunized against C57BL/6J alloantigens produced complement-dependent cytolytic activity against C57BL/6J corneal cells in vitro. Passive transfer of this alloantiserum to T-cell-deficient BALB/c nude mice produced complement-dependent corneal lesions, resulting in significantly increased opacity of C57BL/6J corneal grafts, compared with the relatively clear grafts in control hosts. CONCLUSIONS: Alloantibody, although not necessary for corneal graft rejection, can produce extensive injury to corneal allografts in a complement-dependent manner.

Topographic analysis of corneal regularity after penetrating keratoplasty.

PURPOSE: To evaluate the accuracy of the Holladay Diagnostic Summary of the EyeSys Corneal Analysis System in predicting the corneal visual acuity potential in patients who have undergone penetrating keratoplasty (PKP). METHODS: Astigmatism patterns, refractive and topographic astigmatism, best spectacle-corrected visual acuity (BSCVA), and hard contact lens (HCL) visual acuity of 54 patients were analyzed 3 months after PKP and compared with the Potential Corneal Acuity (PCA) value predicted by the Holladay Diagnostic Summary. RESULTS: Qualitative patterns of astigmatism (p = 0.01) and refractive (p = 0.002) and topographic (p = 0.0002) astigmatism were significantly correlated with PCA values. Using HCL visual acuities to correct the BSCVA (HCL-corrected BSCVA) for noncorneal causes of reduced vision, we found that the PCA values of 48.1% of the patients were within one line of the HCL-corrected BSCVA; 81.5% were within two lines; and 93.0% were within three lines. CONCLUSION: The Holladay PCA measurement may be useful in the postoperative evaluation of the optical quality of the central corneal surface in patients who have undergone PKP.

Cellular changes in transplanted human corneas.

PURPOSE: To measure endothelial cell and keratocyte densities in transplanted corneas and the changes in these densities with time. METHODS: The endothelia of 500 consecutive penetrating corneal transplants were studied longitudinally by specular microscopy for 10 to 20 years. The keratocytes of 36 corneal transplants that varied in postoperative times from 1 month to 20 years were studied cross-sectionally by clinical confocal microscopy. The keratocytes of five transplanted corneas were studied longitudinally by confocal microscopy at 1 day, 1 week, and 1 month postkeratoplasty. RESULTS: Endothelial cell density decreased progressively at an accelerated rate for 20 years after transplantation, with concurrent increases in the coefficient of variation of cell area and corneal thickness and decreases in the percentage of hexagonal cells. Grafts with insufficient endothelial cells developed late endothelial failure, which was the primary cause of graft failure after the first 5 postoperative years. The grafts with late endothelial failure did not lose endothelial cells faster than grafts that did not fail, but instead had fewer cells immediately after transplantation, diminishing to a critically low cell density earlier. The keratocyte density was also decreased in transplanted corneas. Keratocytes became "activated" during the first week after keratoplasty and in grafts with late endothelial failure. CONCLUSION: It should be possible to prevent or delay late endothelial failure, the primary cause of graft failure, by increasing the number of endothelial cells on transplanted corneas. The status of the keratocytes appears to affect corneal transparency and, thus, visual quality in the grafted eye.