Corneal graft survival after therapeutic keratoplasty for Acanthamoeba keratitis

PURPOSE

To describe corneal graft survival and visual outcome after therapeutic penetrating keratoplasty in patients with Acanthamoeba keratitis (AK) that is unresponsive to clinical treatment.

METHODS

Retrospective study. Thirty-two patients with AK who underwent therapeutic penetrating keratoplasty (tPK) from August 1996 to August 2005 were included. Data relating to clinical features, visual acuity, surgical technique, graft survival and complications were collected. Graft survival was evaluated by the Kaplan-Meier method and comparisons were performed using the Log-rank test.

RESULTS

Most patients (62.5%) were female. Mean age [+/- standard deviation (SD)] was 35 (+/- 13) years (range 15-68 years). All patients were contact lens wearers. Eighteen patients (56%) presented paralytic mydriasis and glaucoma during the treatment. Thirteen patients (40%) developed glaucoma after surgery; eight of them (61%) required a second PK because of graft failure. Of the 32 keratoplasty eyes, 56.2% presented graft failure at any follow-up point. Forty-five per cent of graft failures occurred before the 12 month follow-up, so 55% remained clear in the first year after surgery. Twelve patients underwent a second PK; seven of them failed and 45% were clear at 1 year. Two patients presented graft recurrence of amoebic infection. There was no significant difference in graft survival when eyes with or without mydriasis were compared (P = 0.40). Eyes with glaucoma presented a significantly shorter graft survival (P = 0.01).

CONCLUSION

Penetrating keratoplasty is a treatment option for eyes that are unresponsive to clinical treatment infections. However, graft survival is poor; postoperative glaucoma is frequent and is associated with shorter graft survival.

Contrast sensitivity in deep anterior lamellar keratoplasty versus penetrating keratoplasty

PURPOSE

To compare the measurements of contrast sensitivity at a distance in patients submitted to penetrating keratoplasty versus patients submitted to deep anterior lamellar keratoplasty for keratoconus treatment.

METHODS

Contrast sensitivity of 15 subjects submitted to penetrating keratoplasty and 15 subjects submitted to deep anterior lamellar keratoplasty have been analyzed through the Functional Acuity Contrast Test (F.A.C.T) 301.

RESULTS

There was no statistically significant difference between the measurements for penetrating keratoplasty and deep anterior lamellar keratoplasty.

CONCLUSION

Contrast sensitivity was similar among the subjects submitted to penetrating keratoplasty and to deep anterior lamellar keratoplasty for keratoconus treatment.

Prolongation of corneal allograft survival by CTLA4-FasL in a murine model

BACKGROUND

To investigate the therapeutic effect of CTLA4-FasL-B7 costimulatory pathway blockage-on graft survival in a murine model of corneal transplantation.

METHODS

Orthotopic penetrating keratoplasty was performed on BALB/c mice. The mice were randomized into four groups: the isograft group, untreated allograft group, cyclosporine A drug delivery system (CsA DDS)-anterior chamber implanted group, and 10 microg/mL CTLA4-FasL-treated group. Allografts were from C57BL/6 mice. Survival time of corneal grafts was evaluated. Immunohistological method and TdT-mediated dUTP Nick End Labeling (TUNEL) were applied for the detection of CD4+ T cells and apoptotic cells in corneal transplants. To assess whether peripheral immune tolerance appeared after the treatment of CTLA4-FasL, CsA DDS-implanted- and CTLA4-FasL-treated BALB/c mice with clear grafts received skin allografts at 4 weeks after keratoplasty, and the status of corneal transplants were observed when skin grafts were rejected.

RESULTS

Allografts in the CTLA4-FasL group (median survival time [MST] = 106 days, p = 0.0042) and the CsA DDS group (MST = 60 days, p = 0.0037) revealed extending survival time, compared with that in the untreated allograft group (MST = 14 days). There were significantly fewer CD4-positive T cells in both the isograft group and the CsA DDS group. In the untreated allograft group, the number of CD4+ T cells gradually increased from day 1 until the final day of observation (day 21). By contrast, it reached a peak on day 7 and then absolutely reduced in the CTLA4-FasL group. Many apoptotic cells were detected on day 7 in the CTLA4-FasL group, but very few were seen in the other groups. Within 30 days of skin-graft rejection, previously healthy and long-standing corneal grafts became rejected in the CsA DDS group but remained clear in the CTLA4-FasL group.

CONCLUSIONS

CTLA4-FasL can prolong the survival time of corneal allografts in mice, exerting a negative regulation on T-cell activation simultaneously by blocking B7 costimulatory signals and inducing Fas-FasL apoptotic pathway. Due to the adjunctive role of FasL, it also appears to be a potential activity of tolerance induction through T-cell apoptotic pathways.

Corneal transplantation in a developing country: problems associated with technology transfer from rich to poor societies

PURPOSE

To evaluate the results of penetrating corneal transplantation at a university hospital in Brazil.

METHODS

A prospective cohort study was conducted on 146 patients who underwent penetrating keratoplasty at the University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Brazil. The participants were followed postoperatively for 36 months or until graft failure.

RESULTS

In this period, 49% of the grafts lost transparency. All the corneal diseases analysed were present in about the same proportions, except for keratoconus and bullous keratopathy, which showed 3% and 73% rates of graft oedema, respectively. Only 8% of the failures could be attributed to rejection. Other variables such as age, multiple surgeries and previous eye conditions could not explain the high rate of graft failure. Non-adherence to postoperative care increased with age, with a significant association between this behaviour and the rate of graft failure in the older age group. Keratoconus seems to be much less demanding and bullous keratopathy seems to be more exigent in terms of corneal transplantation than other corneal diseases.

CONCLUSION

Although it involves an apparently simple surgical procedure, corneal transplantation is a demanding enterprise that can lead to very poor results under unfavourable conditions.

Long-term changes in corneal surface configuration after penetrating keratoplasty

PURPOSE

To examine the long-term longitudinal changes in corneal surface configuration as determined by Fourier series harmonic analysis of videokeratography data and of visual acuity and refraction after penetrating keratoplasty (PK).

DESIGN

Interventional case series.

METHODS

One hundred thirty eyes of 130 consecutive patients who were scheduled for PK using 16 interrupted 10-0 nylon sutures were recruited. Spherical equivalent power, regular astigmatism component, irregular astigmatism (asymmetry and higher-order irregularity) component of the central cornea as determined by Fourier analysis of videokeragraphic data, spectacle-corrected visual acuity, and spherical equivalent were examined at 1 week, and at 1, 3, 6, 9, 12, 18, and 24 months after PK.

RESULTS

Spherical equivalent power increased considerably for up to 1 month after PK, but thereafter showed no further appreciable change up to the final follow-up at 24 months. The regular astigmatism component decreased markedly for up to 6 months after PK, while the total irregular astigmatism (sum of the asymmetry and higher-order irregularity) component decreased considerably up to approximately 3 months, and then these showed no further relevant change for up to 24 months. Spectacle-corrected visual acuity also improved markedly until approximately 3 months after PK, after which it was virtually stable. Furthermore, important correlations were found between regular and irregular astigmatism and the spectacle-corrected visual acuity.

CONCLUSIONS

Corneal surface configuration after PK appears to be stable by approximately 6 months after PK, concurrent with postkeratoplasty stabilization of visual acuity.

The long-term results of keratoplasty in eyes with a glaucoma drainage device

PURPOSE

To study the outcome of penetrating keratoplasty (PK) in eyes with a glaucoma drainage device (GDD).

DESIGN

Retrospective case-controlled study.

METHODS

We reviewed all patients who underwent PK from December 1986 to September 2002 at the University of California, Davis (n = 1,974). We identified 33 patients (40 grafts) who were treated with a GDD and followed up for 6 months or more after PK. Graft survival and glaucoma control were compared with grafts in patients without glaucoma (n = 40) and patients with medically controlled glaucoma (n = 17). Kaplan-Meier survival analysis, log rank test, repeated-measures analysis of variance (ANOVA), Fisher exact test, and chi(2) were used in group comparisons. Multivariate analysis was performed using the Cox proportional hazards model.

RESULTS

The percentages of clear grafts in the glaucoma drainage device group were 58.5% and 25.8% at 1 and 2 years, respectively. At these time points, glaucoma was controlled in 74.0% and 63.1% of the eyes, respectively. Both medically controlled glaucoma patients and nonglaucomatous patients had higher graft survival percentages at comparable time points. The presence of a GDD was an important factor influencing graft survival (Hazard ratio = 6.8).

CONCLUSION

A GDD implant is an independent risk factor for graft failure. Although these devices are effective in controlling intraocular pressure (IOP) in the majority of eyes in the presence of PK, corneal graft clarity is often compromised.

Quality of vision following clinically successful penetrating keratoplasty

PURPOSE

To evaluate visual function following clinically successful penetrating keratoplasty (PKP).

SETTING

Department of Ophthalmology, Ege University, School of Medicine, Izmir, Turkey.

METHODS

Patient group (PG) included 9 patients (12 eyes) who had clinically successful PKP in our department. The control group (CG) included 12 people (18 eyes) who had no ocular disease other than refractive errors. Those with a visual acuity level less than 20/25 were not included in the study. Contrast sensitivity levels and light threshold values of the central retina were measured; scanning-slit corneal topography-pachymetry and aberrometric analysis were performed.

RESULTS

There were no statistical difference in terms of age (32.55 years +/- 9.25 (SD) in PG, 36.75 +/- 5.85 years in CG; P =.53), cylinder power in plus form (2.60 +/- 1.25 diopter (D) in PG, 2.79 D +/- 2.51 D in CG; P =.88), and spherical equivalent of refractive errors (-3.66 +/- 3.57 D in PG, -5.52 +/- 3.37 D in CG; P =.29) between the PG and CG. Cambridge low-contrast grating scores were 96.5 +/- 41.1 in grafted eyes and 148 +/- 27.7 in CG (P =.004). Central retinal light sensitivity was measured as 29.91 +/- 2.39 db in PG and 33.08 +/- 1.56 db in CG (P =.001). In corneal topographic analysis, mean kappa intercept was 0.69 +/- 0.37 mm in PG and 0.55 +/- 0.24 mm in CG (P =.20). Lower-order Zernike root mean squares (RMS) were 7.30 +/- 3.89 microm for PG and 8.58 +/- 3.46 microm for CG (P =.37). However, higher-order Zernike RMS were 2.15 +/- 0.78 in PG and 0.38 +/- 0.10 in CG, which is a statistically significant difference (P<.001).

CONCLUSIONS

Even though the clinically successful PKP patients have correctable amount of spherocylindrical refractive errors with spectacle lenses, they still have reduced visual quality because of the significantly high amount of higher- order aberrations when compared with naturally occurring refractive errors.

Low endothelial cell count and clear corneal grafts

Specular microscopic study on clear corneal grafts indicates that at times surprisingly low endothelial cell density can maintain the grafted cornea in a relatively dehydrated state. The critical limit of the endothelial cell count for corneal decompensation is thought to be 700 cells/mm2. This communication reports 13 cases of clear corneal graft with endothelial cell count below 700 cells/mm2.

Assessment of visual function after corneal transplantation: the quality of life and psychometric assessment after corneal transplantation (Q-PACT) study

PURPOSE

Many patients with successful corneal grafts have poor vision postoperatively. This study evaluates changes in vision-related quality of life after penetrating keratoplasty (PK).

DESIGN

Multicenter prospective cohort study.

METHOD

Penetrating keratoplasty candidates from the university-affiliated ophthalmology clinics of four participating centers were enrolled and followed up prospectively. We used the PK-VFQ, a modified version of the Visual Function Index-14, combined with clinical examinations before and at 6 and 12 months after PK. We used multivariate linear regression models to examine predictors of change in PK-VFQ scores.

RESULTS

We studied 74 grafts in 71 eyes of 67 patients aged 23 to 91 (mean, 61) years who were followed up for at least 6 months. Indications for surgery included bullous keratopathy (27%), scarring (16%), keratoconus (16%), dystrophies (16%), and regrafts (15%). Median preoperative visual acuity was 20/200 in the graft candidate and 20/30 in the best eye. Median best-corrected postoperative visual acuity in the operated eyes was 20/60 at 6 months. PK-VFQ scores improved at 6 months in 79% by an average of 13.0 points (range, -16.7 to 67.5). Improvement in PK-VFQ scores was associated with younger age (P =.04), poorer preoperative visual acuity in the best eye (P =.001), and postoperative contact lens use (P =.04) but not with postoperative acuity in the grafted eye (P =.49). Postoperatively, 80% of patients were moderately to very satisfied with their vision, and 97% of patients stated they would have the surgery again.

CONCLUSIONS

Improvement in visual function is inversely associated with visual acuity in the better-seeing eye but does not correlate with the postoperative acuity in the grafted eye. Although most keratoplasties are done unilaterally in the setting of good visual acuity in the contralateral eye, for the majority of patients visual function improves after PK.

Excimer laser "corneal shaping": a new technique for customized trephination in penetrating keratoplasty. First experimental results in rabbits

PURPOSE

The aim of the presented experimental work was to develop a technique for congruent trephination of donor and recipient corneas in free form using a 193-nm excimer laser and to study the clinical follow-up after the application of the technique in a rabbit model.

METHODS

In 12 New Zealand White rabbits homologous penetrating keratoplasty was performed. Trephination of donor buttons and recipient beds was achieved in six animals by conventional mechanical trephination and in six by excimer laser trephination with a guided laser beam in a non-circular geometry. The surgical procedure and its applicability to human subjects were evaluated and the postoperative clinical course was followed for 6 months.

RESULTS

The surgical procedure of full-thickness excimer laser trephination could be performed reproducibly in the animal model both for dissection of the donor buttons and for preparation of the recipient beds. Keratoplasty was performed with kidney-shaped transplants after trephination in free form with the guided laser beam. Postoperative clinical follow-up did not show any differences between the two trephination groups that could be related to the applied trephination technique. After 6 months we observed well-adapted and clear corneal grafts, kidney-shaped in the excimer trephination group and circular in the mechanical trephination group. No side effects on the crystalline lens and the central retina could be clinically observed following excimer laser trephination.

CONCLUSION

We present the first experimental study of keratoplasty with freely selected transplant geometry and perfect congruence of donor button and recipient bed. The application of this technique in certain corneal disorders in humans will offer improved treatment options in the future.

The influence of keratoplasty on visual prognosis in aniridia: a historical review of one large family

PURPOSE

To evaluate the visual prognosis in aniridia and the influence of keratoplasty in one large family.

METHODS

The medical charts of 30 affected members of this family were studied retrospectively. Their eyes were divided in keratoplasty and nonkeratoplasty groups. In the keratoplasty group, 42 keratoplasties (26 lamellar and 16 penetrating) were performed (20 eyes), with a median follow-up of 18.5 years. In the nonkeratoplasty group, 18 eyes with sufficient follow-up were included. Best corrected visual acuity ever measured (BCVA-ever), BCVA at the last visit (end-BCVA), and the difference between BCVA-ever and end-BCVA (long-term Delta-BCVA) were compared in those two groups. Best postoperative VA (post-BCVA), the difference between pre- and post-BCVA (short-term Delta-BCVA), and its duration and outcomes of the grafts were evaluated in the keratoplasty group. Possible side effects of other procedures and incidents related to aniridia were compared.

RESULTS

The median BCVA-ever was 1/10 in both groups. The median end-BCVA was 2/300 in the keratoplasty group and 1.5/300 in the nonkeratoplasty group; the long-term Delta-BCVA was comparable in the two groups. There was a temporary improvement of BCVA in 36 of 42 eyes after corneal transplantation, with a median of 8 logMAR and duration of 12 months. Most grafts failed because of recurrence of aniridic keratopathy. In the keratoplasty group, there were more corneal infections and more retinal detachments. The occurrence of glaucoma was comparable in both groups. In the nonkeratoplasty group, more eyes (five versus three) lost light perception.

CONCLUSION

Corneal transplantation in aniridia provided only a temporary improvement in VA in this family. The long-term visual outcome was not affected by keratoplasty.

Temporal contrast sensitivity using full-field flicker test (Erlangen flicker test) in patients after penetrating keratoplasty

BACKGROUND

The purpose of this study was to evaluate the feasibility of temporal contrast sensitivity testing using full-field flicker stimulation in patients after penetrating keratoplasty (PK) and to assess whether this method is influenced by postoperative corneal topographic changes.

METHODS

Forty-five patients (age 46.5+/-14.2, median 47 years) who had undergone PK and 194 age-matched controls were included in this study. The postoperative interval was 11.8+/-10.2 months (median 9 months). Patients with pre-existing glaucoma or any postoperative intraocular pressure elevation were excluded. The indications for PK were keratoconus in 54% of cases, Fuchs' dystrophy in 38% and stromal dystrophies in 8%. Temporal contrast sensitivity was determined with sinusoidal flickering light (37.1 Hz) of constant mean photopic luminance (10 cd/m(2)) presented in a full-field bowl with an increasing threshold strategy.

RESULTS

Mean temporal contrast sensitivity did not differ between patients after PK (1.49+/-0.13, range 1.26-1.78, confidence interval 1.45-1.53) and controls (1.55+/-0.17, range 1.16-1.98, confidence interval 1.47-1.51). No significant correlation between temporal contrast sensitivity and visual acuity could be found in patients after PK or in normals ( r<0.2, P=0.3). In patients after PK, temporal contrast sensitivity was statistically independent of keratometric astigmatism ( r=0.3, P=0.7), topographic astigmatism ( r=0.3, P=0.4), spherical equivalent ( r=0.07, P=0.7), central corneal thickness ( r=-0.06, P=0.7) and time since operation ( r=-0.07, P=0.6).

CONCLUSIONS

Temporal contrast sensitivity using full-field flicker stimulation seems to be feasible in patients after PK and does not depend on topographic changes of the cornea. The results indicate that the full-field flicker test may be helpful as a supplementary means of detecting early glaucoma caused by ocular hypertension in patients after PK.

Use of a Shack-Hartmann aberrometer to assess the optical outcome of corneal transplantation in a keratoconic eye

We report the optical outcome of corneal transplantation treatment on a keratoconic eye as measured with a Shack-Hartmann aberrometer, and we compare the results with the recovery of visual acuity after surgery. Before surgery, the naked keratoconic eye exhibited extremely large aberrations that could not be measured unless the patient wore a rigid gas-permeable contact lens. With the lens, the computed point-spread function of the eye was large and multimodal, and simulated retinal images confirmed the patient's subjective report of multiple, overlapping images. After full recovery from surgery, aberrations of the corrected eye were much smaller compared with the presurgical eye, which implied a more compact point-spread function and clearer retinal images. These optical changes were mirrored by an improvement in uncorrected visual acuity from 1.3 logarithm of the minimum angle of resolution (logMAR) before surgery to 0 logMAR with spectacle correction after full recovery. We conclude that the Shack-Hartmann aberrometer provides an objective, quantitative assessment of the optical outcome of penetrating keratoplasty that allows the clinician to measure retinal image quality objectively and to accurately simulate the complex visual distortions associated with keratoconus.

Corneal graft survival and intraocular pressure control after penetrating keratoplasty and glaucoma drainage device implantation

OBJECTIVE

To investigate corneal graft survival rates and intraocular pressure (IOP) control in eyes after penetrating keratoplasty (PK) and glaucoma drainage device (GDD) implantation.

DESIGN

Retrospective, comparative, consecutive case series.

PARTICIPANTS

All patients who underwent PK and GDD implantation at the Bascom Palmer Eye Institute between January 1, 1993 and October 31, 1998.

MAIN OUTCOME MEASURES

Graft clarity and IOP control.

RESULTS

Of the 72 eyes in 72 patients identified, 47 (65%) underwent combined PK and GDD implantation, and 25 (35%) underwent GDD placement after PK (2-30 months after PK; median, 13 months). The GDD type was Baerveldt 350 mm(2) in 57 eyes, Ahmed in 9, Krupin in 2, and other in 4 eyes. The GDD was placed in the anterior chamber in 54 eyes (75%) and in the vitreous cavity in 18 eyes (25%). Preoperative IOP was 11 to 53 mmHg with or without antiglaucoma medications in 16 eyes (30%) with the GDD implanted in the anterior chamber and in 4 eyes (22%) with the GDD placed in the vitreous cavity (P = 0.76). At 1 year after GDD implantation, the graft was clear in 26 eyes (48%) with the GDD in the anterior chamber compared with 15 eyes (83%) with the GDD in the vitreous cavity (P = 0.013). Forty-eight eyes (89%) with the GDD in the anterior chamber and 18 eyes (100%) with the GDD in the vitreous cavity had IOP between 5 and 21 mmHg with or without antiglaucoma medications (P = 0.33). The mean reduction in IOP, 1 year after surgery, was 12 mmHg among eyes with the GDD in the anterior chamber, compared with 17 mmHg among eyes with the GDD in the vitreous cavity (P = 0.13)

CONCLUSIONS

Corneal graft survival at 1 year is significantly higher among eyes with the GDD implanted in the vitreous cavity compared with those in which the GDD is implanted in the anterior chamber. The IOP was significantly lower at 1 year after surgery compared with before surgery in both groups, and there was no significant difference between the groups in IOP control and amount of IOP reduction. There was no significant difference in corneal graft survival or IOP control between eyes with the GDD implanted concurrently with the PK versus after the PK.

Long-term follow-up of corneal graft survival following bone marrow transplantation in the Maroteaux-Lamy syndrome

PURPOSE

To present a case of Maroteaux-Lamy syndrome (MLS, mucopolysaccharidosis [MPS] type VI) who underwent bone marrow transplantation (BMT) for gene transfer at the age of 13, and penetrating keratoplasty at the age of 17, and maintained clear corneal grafts bilaterally for 13 years. To our knowledge, this is the longest follow-up reported on corneal graft survival in a patient with MLS and BMT.

METHODS

In 1982, BMT was successfully performed on a 13-year-old girl with MLS with growth retardation, typical facial features, skeletal and joint deformities, hepatosplenomegaly, cardiopulmonary dysfunction, and corneal clouding. Corneal transplantation was done on the left eye in 1986, and on the right eye in 1987 (6 months later) without difficulty or complication.

RESULTS

Thirteen years postoperatively, the patient was systemically well, and both eyes retained clear corneal grafts.

CONCLUSION

BMT retarded further dysfunction from MLS, and the corneal transplants retained clarity. Further controlled studies with longer follow-up are required to establish the efficacy of BMT in ocular manifestations of MPS or MLS.

Keratometric results during the first year after keratoplasty: adjustable single running suture technique versus double running suture technique

BACKGROUND AND OBJECTIVE

To compare the 3-month and 1-year postoperative keratometric results in a retrospective sequential series of corneal grafts performed with either a double running suture technique or an adjustable single running suture technique.

MATERIALS AND METHODS

Keratometry values obtained 3 months and 1 year after penetrating keratoplasty, when sutures were still present, were compared between 31 grafts with double running sutures and 27 grafts with single running sutures, 15 of which had been adjusted postoperatively.

RESULTS

No significant difference in mean keratometry between the 2 groups was found either 3 months or 12 months after keratoplasty. Mean keratometric astigmatism was significantly less in the single running group at both 3 months (2.2 +/- 1.9 vs 4.5 +/- 2.8, mean +/- SD, P <0.001) and 12 months (3.0 +/- 2.2 vs 4.2 +/- 2.1, P = 0.03). Within groups, there was no significant change from 3 months to 12 months in either mean keratometry or keratometric astigmatism.

CONCLUSION

The single running suture technique, with postoperative adjustments, produced less keratometric astigmatism during the first postoperative year, when sutures were still in place.

Role of recipient epithelium in promoting survival of orthotopic corneal allografts in mice

PURPOSE

To determine whether epithelium-deprived corneal allografts covered with syngeneic epithelium display immune privilege in orthotopic transplantation and whether syngeneic epithelium containing antigen-presenting cells nullifies this effect.

METHODS

Epithelium-deprived allogeneic corneas (C57BL/6) and epithelium-deprived allogeneic corneas reconstituted with syngeneic (BALB/c) epithelium (containing or deprived of Langerhans' cells) were transplanted orthotopically into normal eyes of BALB/c mice. Graft survival was assessed clinically and evaluated histologically.

RESULTS

Epithelium-deprived corneal grafts survived in syngeneic recipients but were swiftly rejected in allogeneic recipients. These allografts incited intense stromal inflammation and neovascularization. Epithelium-deprived allografts that were resurfaced in vivo by syngeneic epithelium derived from immune-incompetent SCID mice also underwent intense acute rejection when placed in normal eyes of BALB/c mice. The epithelium of in vivo resurfaced grafts was replete with Langerhans' cells. By contrast, most of the epithelium-deprived allografts reconstituted in vitro with fresh, normal BALB/c corneal epithelium survived indefinitely when placed in eyes of BALB/c mice. Similar grafts reconstituted with BALB/c epithelium containing Langerhans' cells were swiftly rejected.

CONCLUSIONS

Replacement of donor epithelium with Langerhans' cell-deficient syngeneic epithelium protects orthotopic allogeneic cornea grafts (stroma plus endothelium) from immune-mediated rejection. The presence of an intact, histocompatible layer of corneal epithelium has two important effects on orthotopic corneal allografts: It suppresses nonspecific inflammation and neovascularization within the graft, and it blunts the alloimmunogenicity of the histoincompatible stroma and endothelium.

Stability of graft refractive power after penetrating keratoplasty

PURPOSE

Patients needing penetrating keratoplasty (PK) and cataract extraction with intraocular lens (IOL) implantation may be handled with a single triple procedure or a two-stage procedure with initial keratoplasty and cataract surgery in a later session. The latter approach is considered more safe by some surgeons and allows adjustment of the IOL power to the power of the actual corneal graft. The purpose of this study was to estimate the optimal timing of cataract surgery with IOL implantation by studying the refractive stability of 8 mm penetrating keratoplasty grafts.

METHODS

Penetrating keratoplasty (8.0 mm graft and recipient bed) was performed in 28 eyes of 28 patients. Corneal topography (TMS-1) was studied at 1, 2, 3, 6, and 12 months after surgery and after suture removal (30 months). The central spherical equivalent graft power was computed from the topographical data (rings 2 through 4).

RESULTS

On average, the spherical equivalent graft power was stable from one month after surgery up to suture removal (range: 41.9 to 42.7 diopters). After suture removal the graft steepened slightly (0.7 diopters). Corneal refractive power of single grafts fluctuated considerably over time. The standard deviation on time-dependent changes in graft power was from 3 months efter PK smaller than the standard deviation on the graft powers at 12 months.

CONCLUSION

The average central spherical equivalent power of an 8.0 mm donor graft in an 8.0 mm recipient bed was stable from one month after penetrating keratoplasty until suture removal. A two-stage procedure with cataract surgery performed 3 months after PK can, compared to the triple procedure, reduce postoperative ametropia at 12 months if graft topography is taken into consideration at the time of cataract surgery. We recommend that cataract surgery with IOL implantation takes place from 3 months after penetrating keratoplasty.

Factors influencing graft clarity

Successful penetrating keratoplasty depends on both host- and donor-related factors. We compared the results of keratoplasty in a group with a wide range of donor ages to gauge the effect of donor age on graft success. We conducted a retrospective review of donor data, recipient age, preoperative diagnosis, and postoperative complications with respect to graft clarity at 24 months after surgery in 99 consecutive patients in an effort to determine the role of donor age in graft clarity. The only factors that we isolated that appeared to influence graft clarity at 24 months postoperatively were a preoperative diagnosis classified as inflammatory/traumatic and the occurrence of postoperative complications. There was no association between graft clarity and recipient age, donor age, death-to-preservation time, or preservation-to-surgery time.

Functional measurements on the enlarged endothelial cells of corneal transplants

PURPOSE

To measure the morphologic and functional status of the endothelium of long-term corneal transplants.

METHODS

We induced hypoxic corneal edema and measured corneal deswelling (expressed as percent recovery per hour, PRPH, over 7 hours) with a modified optical pachometer in 12 corneas of 8 patients transplanted 7-18 years previously and in 21 normal adult control subjects. Fluorophotometry and specular microscopy were also performed on each eye. Results in the 2 groups were compared with a 2-tailed Student T test for means.

RESULTS

The transplanted corneas had significantly decreased PRPH, induced swelling, endothelial permeability to fluorescein, and endothelial cell density compared to the controls, despite a similar estimated open-eye steady-state thickness.

CONCLUSIONS

The markedly enlarged endothelial cells of long-term corneal transplants have a reduced ability to deturgesce the cornea and decreased permeability to small solutes. These findings could result from a reduction in intercellular space that occurs when the number of cells lining the posterior surface of the cornea is substantially decreased.

The epithelial barrier function in clear corneal grafts

We conducted a corneal epithelial permeability study using a fluorophotometer on 93 eyes of 79 patients with clear corneal grafts. There were 45 males and 34 females, aged 61.6 +/- 10.2 years. All eyes received penetrating keratoplasty at least 1 year (mean 40.4 +/- 31.3 months) before examination. The normal fellow eyes of 65 subjects were examined as controls. The averaged corneal epithelial permeability of grafted corneas was significantly higher than that of controls (p < 0.001). In the 65 individuals having an otherwise healthy fellow eye, the grafted corneas were significantly more permeable than their control fellow eyes verified by paired t test (n = 65, p = 0.006). Concomitant corneal sensitivity test revealed a significantly hypesthetic cornea. These results show that in spite of a clinically normal clear graft, there is usually a subnormal epithelial barrier function and reinnervation, even years after corneal transplantation.