Effects of posterior chamber lens implantation on the endothelium of transplanted corneas

AIMS—The morphological changes of the corneal endothelium after posterior chamber lens implantation in the transplanted corneas were investigated.
METHODS—36 patients underwent extracapsular cataract extraction with posterior chamber lens implantation. Among these, penetrating keratoplasty had been performed in 18 patients before cataract surgery. The indications for penetrating keratoplasty in these cases included keratoconus, herpetic keratitis, and macula cornea. 18 cataract patients with normal corneas were also studied as controls. The central corneal endothelium in each subject was examined with a wide field specular microscope at a few days before and 3 months after cataract surgery.
RESULTS—Although the transplanted corneas showed lower endothelial cell densities, marked polymegethism, and pleomorphism in the baseline variables, the endothelial morphological changes in the transplanted corneas after posterior chamber lens implantation were comparable with those in the normal corneas. Also, there was no clinical evidence, especially, of corneal epithelial and/or endothelial rejections and corneal decompensation in all corneas.
CONCLUSION—Even though the transplanted corneas have a lower endothelial cell density and marked polymegethism, it is believed that cataract surgery does not induce corneal decompensation in cases where the peripheral recipient endothelium can be considered to have normal morphology.

     

Influence of advanced recipient and donor age on the outcome of corneal transplantation

AIMS—The aims of this study were to examine the influence of advanced recipient and donor age on the long term outcome of corneal transplantation.
METHODS—Records of 1036 penetrating corneal grafts in recipients aged 80 years at surgery (defined as the elderly subset) and 8092 donor corneas used for transplantation were obtained from the Australian Corneal Graft Register database. Kaplan-Meier graft survival plots were compared using log rank statistics.
RESULTS—Elderly recipients constituted 15% of the recipient pool. The major indication for corneal transplantation in the elderly was bullous keratopathy. Graft survival fell with increasing recipient age (p < 0.00001); the major cause of graft failure was rejection (33%). The desired outcome in 51% of cases was to improve vision and in 42% of cases to relieve pain; 23% of elderly recipients achieved a Snellen acuity of 6/18 or better in the grafted eye and 66% recorded improved acuity after transplantation. Elderly recipients suffered more complications and comorbidities in the grafted eye than did younger recipients. Donor age (stratified in 10 year intervals) did not influence corneal graft survival significantly (p = 0.10).
CONCLUSIONS—Elderly graft recipients fared less well after corneal transplantation than did younger recipients, but outcomes in terms of long term graft survival and visual rehabilitation were still good. Donor age did not affect graft survival.

     

Oral immunisation as a strategy for enhancing corneal allograft survival

AIMS—To determine optimal conditions for enhancing corneal allograft survival through oral administration of donor specific corneal cells.
METHODS—A mouse model of penetrating keratoplasty was used to evaluate the efficacy and optimal conditions for preventing immunological rejection of corneal allografts. C3H corneal grafts were transplanted orthotopically to CB6F1 recipients and represented mismatches at the entire major histocompatibility complex (MHC) and multiple minor histocompatibility loci. Tissue cultured C3H corneal epithelial and endothelial cells were administered orally to CB6F1 mice before or shortly after the application of orthotopic C3H corneal allografts. Cultured C3H corneal cells were conjugated with the non-toxic B subunit of cholera toxin as a means of preferentially inducing oral tolerance.
RESULTS—Ten oral doses of donor cells administered before keratoplasty reduced the incidence of corneal graft rejection from 100% in untreated hosts to 54% in orally tolerised mice. Conjugation of cholera toxin to corneal cells significantly enhanced the efficacy of oral tolerance such that only 9% of the mice fed 10 doses of cholera toxin conjugated cells rejected their corneal grafts. Even a single oral inoculation of corneal cells conjugated to cholera toxin was able to reduce corneal graft rejection by 36%.
CONCLUSIONS—Oral administration of donor specific cells greatly enhances corneal graft survival. Use of cholera toxin adjuvant markedly enhances the efficacy of oral tolerance such that even a single oral dose of donor cells significantly reduces the incidence of rejection. The results support the clinical feasibility of this novel strategy for preventing immunological rejection of corneal transplants.

     

Endotoxins modulate the autocrine function of organ cultured donor corneas and increase the incidence of endothelial cell death

BACKGROUND/AIMS—Bacterial endotoxin is a potent inflammatory stimulator, the local and systemic responses thereby elicited being mediated via the release of cytokines from diverse cell types. Under physiological conditions, the corneal endothelium is protected from these toxins by the epithelial and vascular barriers, but in organ culture these safeguards are no longer operative, and such substances will therefore have ready access to this cell layer. The consequences of such exposure may take the form of overt damage to the endothelium and/or a more discreet influence on the cornea's immunological status, the effects of which may be realised only after transplantation, by its poor performance. The media bathing organ cultured donor corneas were monitored for the presence of various cytokine mediators of the inflammatory response before and after incubation with endotoxin, and these data compared with those pertaining to endothelial cell morphology and numerical density.
METHODS—Six pairs of fellow donor corneas were cultured for an initial equilibration period of 10 days and then transferred to fresh medium; thereafter, one of each pair was incubated in the absence, and the other in the presence, of endotoxin (50 µg/ml  25 000 units/ml), and culturing continued for a further 10 days. Samples of medium were withdrawn at regular intervals throughout the 20 days and screened for the cytokines IL-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, GM-CSF, and TNF by ELISA; endothelial cell morphology and area density were assessed on days 0, 10, and 20.
RESULTS—Spiking of organ culture media with endotoxin led to a substantial increase in the level of IL-8, and a smaller one in that of IL-6, but none of the other cytokines were detected. In five of the six stimulated corneas, these changes coincided with an increased incidence of endothelial cell loss, compared with that incurred by the fellow control, and the surviving population also evinced signs of degeneration not seen in the latter.
CONCLUSION—Endotoxin induced increases in the levels of IL-6 and IL-8 appear to be correlated with endothelial cell loss. Since no adverse effects of this toxin on long term cultured monolayers of human corneal endothelial cells have been previously observed, the damage incurred in corneal organ culture may well be attributable to the influence of cytokines produced by other corneal cells or a non-intrinsic (passenger) cell population, such as macrophages, Langerhans cells, or lymphocytes present under these latter conditions.

     

Corneal thickness and endothelial density before and after cataract surgery

BACKGROUND/AIMS—Deturgescence of the corneal stroma is controlled by the pumping action of the endothelial layer and can be monitored by measurement of central corneal thickness (pachymetry). Loss or damage of endothelial cells leads to an increase in corneal thickness, which may ultimately induce corneal decompensation and loss of vision. Little is known about the effect of moderate reductions in endothelial cell number on the thickness of the corneal stroma. This study aimed to investigate this matter further using patients who had incurred moderate decreases in their endothelial cell counts as a result of cataract surgery.
METHODS—Central corneal thickness was measured 1 day before surgery, 1 day after surgery, and again at 3 months or 1 year. Endothelial cell counts were also performed 1 day before surgery and thereafter at 3 months or 1 year after surgery. The relationship between these two parameters was assessed statistically. Precise measurements of central corneal thickness were made by optical low coherence reflectometry. For comparative purposes, this parameter was also determined by ultrasonic pachymetry. Central corneal endothelial cell numerical density was estimated on photomicrographs taken with a specular microscope.
RESULTS—All patients had significant postoperative corneal swelling on the day after surgery; preoperative values were restored by 3 and 12 months, even though significant endothelial cell losses had occurred. No correlation existed between central corneal thickness and central corneal endothelial cell numerical density. Measurements estimated by ultrasonic pachymetry were more variable and significantly higher than those determined by optical low coherence reflectometry.
CONCLUSION—As long as the numerical density of the corneal endothelial cells does not fall below the physiological threshold, a moderate decrease in this parameter does not compromise the pumping activity of the layer as a whole.

     

Expression of adhesion molecule CD44 on human corneas

AIMS—This study was undertaken to confirm the distribution and expression of the molecule CD44 on human corneas under normal and pathological conditions.
METHODS—Fifty eight corneal buttons from adult patients suffering from various corneal diseases and four normal corneas were included in this study. Frozen sections were stained immunohistochemically with monoclonal antibodies against human CD44 using an APAAP method and observed under a light microscope.
RESULTS—In normal corneas CD44 was predominantly expressed on the membranes of basal epithelial cells and on the keratocytes, as well as on the vascular endothelial cells of the corneal limbi, but was not expressed on corneal endothelial cells. Enhanced expression of CD44 was observed on the epithelium of corneas with inflammation and allograft rejection. In a number of abnormal conditions including allograft rejection, corneal trauma, primary and secondary corneal endothelial decompensation the remaining endothelial cells stained positively for CD44. However, in some corneas of keratitis, keratoconus, and dystrophy the endothelium which appeared relatively integral in morphology and amount remained CD44 negative.
CONCLUSIONS—These results suggest that CD44, the hyaluronate receptor, may play an important role in corneal cell-cell and cell-matrix interactions. Its regulation is closely related to corneal inflammatory reactions. The induction of CD44 on corneal endothelium might play a potential role in compensatory processes when corneal endothelial cells are injured.

     

Successful visual rehabilitation after neonatal penetrating keratoplasty

BACKGROUND—Penetrating keratoplasty in infancy and childhood has traditionally met with limited visual success due to a combination of unique physiology and technical problems in this patient population. With the advances in microsurgical instrumentation, corneal preservation, and visual developmental physiology ophthalmologists are finding increasing indications for penetrating keratoplasty in the childhood population. The long term results of neonatal penetrating keratoplasty in two patients with unilateral congenital corneal opacification are reported.
METHODS—Penetrating keratoplasty was performed on one eye in each of two infants within the first 3 weeks of life. Amblyopia treatment and optical therapy have been continued since surgery.
RESULTS—After 6 years both grafts have remained clear. One patient developed the infantile esotropia syndrome. Visual development using Snellen optotypes is age normal for both transplanted eyes.
CONCLUSIONS—Penetrating keratoplasty when combined with optical correction and amblyopia therapy may restore and preserve vision in selected patients with congenital corneal opacification if performed in the neonatal period.

     

Survival analysis and visual outcome in a large series of corneal transplants in India

AIM/BACKGROUND—The public health significance of corneal transplantation in dealing with corneal blindness in the developing world would depend upon the survival rate of transplants. This study was done to analyse the survival rate of corneal transplants in a large series in India, and to evaluate the influence of various risk factors on transplant survival.
METHODS—The records of a series of 1725 cases of corneal transplants carried out during 1987-95 at a tertiary eye care institution in India were reviewed. The Kaplan-Meier method was used to determine 5 year survival rates of corneal transplants performed for the various categories of preoperative diagnosis. Multivariate Cox proportional hazards regression was used to assess how preoperative diagnosis, socioeconomic status, age, sex, vascularisation of host cornea, quality of donor cornea, and training status of surgeon influenced transplant survival. The effect of these variables on visual outcome was assessed using multiple logistic regression.
RESULTS—The survival rates at 1, 2, and 5 years for all corneal transplants performed for the first time in 1389 cases were 79.6% (95% confidence interval = 77.3-81.9%), 68.7% (65.7-71.7%) and 46.5% (41.7-51.3%). The 5 year survival rate was highest if the corneal transplant was done for keratoconus (95.1% (84.8-100%)) and lowest if carried out for previous transplant failure (21.2% (13.8-28.6%)). The relative risk of transplant failure was higher if the preoperative diagnosis was previous transplant failure (2.04 (1.62-2.55)), aphakic bullous keratopathy (1.78 (1.38-2.28)), corneal clouding due to miscellaneous causes including congenital conditions and glaucoma (1.63 (1.21-2.19)), or adherent leucoma (1.11 (0.81-1.51)) than for the other preoperative diagnoses. Patients with lower socioeconomic status had higher relative risk of transplant failure (1.28 (1.16-1.42)), as did patients <10 years of age (1.42 (1.23-1.64)). Higher relative risk of transplant failure was associated with vascularisation of the host cornea before transplantation (1.15 (1.04-1.27)), and with the use of fair quality donor cornea for transplantation compared with excellent, very good, or good quality donor cornea (1.26 (1.06-1.52)). Before corneal transplant 80.2% of the eyes were blind (visual acuity <3/60), whereas at last follow up 41.8% eyes were blind. The odds of having visual acuity >6/18 were higher if the transplant was done for keratoconus (9.99 (6.10-16.36)) or corneal dystrophies (1.77 (1.21-2.58)) than for the other preoperative diagnoses.
CONCLUSION—Reasonable success with corneal transplantation is possible in the developing world if data from this part of the world regarding the different survival rates for the various preoperative diagnoses and the influence of risk factors on transplant survival and visual outcome are taken into account while determining priority for transplant cases in the present situation of limited availability of donor corneas.

     

A murine model of interlamellar corneal transplantation

AIMS/BACKGROUND—There are more reagents and information available for immunological studies in the mouse compared with other animals. Unfortunately, the mouse penetrating keratoplasty model is associated with high background inflammation which hinders study of the immune response to the graft. To mitigate this drawback, a murine orthotopic corneal interlamellar transplantation model with mild non-specific inflammation was developed.
METHODS—A 1.5 mm diameter full thickness donor corneal button was placed in a 2 mm diameter recipient corneal interlamellar pocket without placement of a suture. The clinical course of graft status was studied daily for 60 days in 30 allografts (donor strain CBA 101 (H-2^k) to recipient NIH (H-2^q)) and 30 syngeneic grafts (NIH to NIH) by slit lamp biomicroscopy and scored for neovascularisation, opacity, oedema, and granularity. In another cohort of animals, histological observation was performed after 30 minutes and on days 10, 20, 30, and 40 after transplantation (four allografts and four syngeneic grafts per time point). Histological study was also performed on grafts without donor epithelium and on interlamellar pockets without grafts.
RESULTS—There was significantly more neovascularisation (NV), opacity, oedema, and granularity in 24/30 allografts (80%) than in syngeneic grafts. Such grafts were defined as rejected. The median time to rejection was 21 days (range 18 to >60 days). By histology, some allografts showed moderate to heavy cell infiltration which correlated with clinical scores of NV (4-5), opacity (1-3), oedema (1-3), and granularity (1-3). Such infiltration was absent in other allografts and syngeneic grafts.
CONCLUSION—Surgically, corneal interlamellar transplantation could be accomplished in the mouse and rejection could be clearly defined. The model can therefore be useful for in situ study of cell and molecular aspects of corneal graft rejection.

Keywords: interlamellar keratoplasty; corneal transplantation; graft rejection; mouse     

Bilateral, anterior stromal ring opacity of the cornea

AIMS/BACKGROUND—To describe a bilateral, mid peripheral, ring-shaped corneal opacity, not resembling any known corneal degeneration, dystrophy, or other disorder, and occurring without ocular or systemic disease.
METHODS—Ophthalmic examination, haematological screening, and ultrasound biomicroscopy.
RESULTS—A 25 year old man showed grey-white, granular opacities in both corneas, with an 8 mm diameter ring configuration, and a V-shaped distribution in the anterior stroma. The surrounding corneal stroma was clear, and the tear film, the epithelium and its basement membrane, Descemet's membrane, and the endothelium were normal. Evidence of systemic disease was not found. Family members did not show corneal abnormalities.
CONCLUSION—A bilateral corneal ring opacity may occur in healthy, asymptomatic, young people. These corneal rings may result from depositions of unknown origin, or possibly a rare corneal dystrophy.

Keywords: cornea; corneal opacity; corneal rings     

Deep lamellar keratoplasty with complete removal of pathological stroma for vision improvement

AIMS/BACKGROUND—Deep lamellar keratoplasty (DLK) was performed to restore visual acuity in 120 eyes with corneal stromal opacification. DLK is believed to be an effective treatment in eyes in which endothelial cell function had been preserved, and in which there was no epithelial or stromal oedema. The purpose of this study was to evaluate the effectiveness of this treatment.
METHODS—The stroma was excised to the extent that only Descemet's membrane remained, at least in the optical zone. Donor corneas of full, or almost full, thickness with Descemet's membrane removed, or which had been lathed to a thickness of 0.4 mm from the endothelial side, were attached by suturing.
RESULTS—In 113 eyes which were observed for 6 months or more postoperatively in which average prospective visual acuity was 0.09, average postoperative visual acuity improved to 0.6. Specular microscopy 1 month postoperatively revealed average endothelial cell counts of 2225 (SD 659)/mm², while 24 months postoperatively this value was 1937 (642)/mm² (cell loss 13%). Puncturing of Descemet's membrane during surgery occurred in 47 of 120 eyes (39.2%), but after 12 months, there was no difference in visual acuity or number of endothelial cells between these eyes and those in which no puncturing had occurred.
CONCLUSIONS—There was no postoperative endothelial rejection reaction with DLK, and restoration of postoperative visual acuity was quite adequate. Compared with penetrating keratoplasty, DLK allows endothelial cell counts to be maintained for a longer period. In addition, results can be expected to be more consistent over the long term with DLK.

     

Clinical results of implantation of the Chirila keratoprosthesis in rabbits

AIMS/BACKGROUND—An ideal keratoprosthesis (KPro) would closely resemble a donor corneal button in terms of its surgical handling, optics, and capacity to heal with host tissue in order to avoid many of the complications associated with the KPros which are currently in clinical use. This study was carried out to assess the long term clinical outcomes on implantation of the core and skirt poly(2-hydroxyethyl methacrylate) KPro in animals.
METHODS—20 KPros were made and implanted as full thickness corneal replacements into rabbits and followed for up to 21 months to date.
RESULTS—80% of the prostheses have been retained, with a low incidence of complications such as cataract, glaucoma, and retroprosthetic membrane formation which are frequently associated with KPro surgery.
CONCLUSIONS—KPros of this type may offer promise in the treatment of patients for whom penetrating keratoplasty with donor material carries a poor prognosis. Refinement of the KPro and further animal trials, including implantation into abnormal corneas, are however mandatory before human implantation could be planned.

Keywords: complications; keratoprosthesis; optics; PHEMA     

Corneoscleral transplantation for end stage corneal disease

AIM—To describe the prognosis and complications of corneoscleral transplantation in the management of end stage eye disease.
METHODS—A case series is presented of 23 patients who have undergone corneoscleral transplantation (11 mm). Patients were examined for visual acuity, intraocular pressure, recurrence of disease process, epithelialisation of the graft, signs of rejection, and other potential complications.
RESULTS—14 patients retained their eye, with six maintaining a clear graft. Vision ranged from 6/30 to no perception of light. 13 patients developed glaucoma (range 25-69 mm Hg), with six patients requiring surgical intervention. 12 patients required tarsorrhaphy to promote epithelialisation. Only two grafts resulted in typical rejection.
CONCLUSIONS—The technique of corneoscleral transplantation can salvage otherwise end stage eye disease, but the results are poor with respect to maintenance of vision. These patients need careful follow up because of potential complications of glaucoma, epithelial defects, rejection, and recurrence of disease.

Keywords: corneoscleral graft; end stage corneal disease; sclerokeratoplasty     

Influence of topical human epidermal growth factor on postkeratoplasty re-epithelialisation

AIM—To test the efficacy and safety of recombinant human epidermal growth factor (hEGF) on corneal re-epithelialisation following penetrating keratoplasty.
METHODS—A prospective, randomised, placebo controlled study was carried out in which patients were matched for diagnosis and received either hEGF ophthalmic solution (30 µg/ml or 100 µg/ml) or placebo in a double masked fashion. Matched pairs of patients received donor corneas from the same donor and were operated by the same surgeon on the same day. At the end of surgery all donor epithelium was removed mechanically. Patients were examined twice daily and fluorescein stained photographs were taken until the epithelium had closed. The area of the defect was measured by planimetry of the fluorescein stained defect on the photographs.
RESULTS—There were no significant differences in re-epithelialisation of the donor cornea between the placebo group and the group treated with 30 µg/ml hEGF. Time until complete closure was slightly longer with 100 µg/ml hEGF compared with 30 µg/ml hEGF and with placebo. Mean healing rate of the epithelial defect with 100 µg/ml hEGF was significantly slower than in the other groups.
CONCLUSION—No significant acceleration of corneal re-epithelialisation was demonstrated with the use of recombinant hEGF after penetrating keratoplasty in humans.

     

Combined PRK and PTK in myopic patients with recurrent corneal erosion

AIM—To study the results of combined photorefractive keratectomy (PRK) and phototherapeutic keratectomy (PTK) in myopic patients with recalcitrant recurrent corneal erosion.
METHODS—PRK was performed in 16 eyes with the Visx 20/20 excimer laser at a central 6.0 mm zone, following total epithelial scraping. Subsequently, confluent 3.0 mm zones of PTK were ablated at a depth of 6.0 µm, surrounding the zone of PRK. The follow up period ranged from 26 to 42 months.
RESULTS—Complete alleviation of symptoms was demonstrated and there was no recurrence of corneal erosion. Visual acuity (VA) improved slowly following treatment, with a final uncorrected VA ranging between 6/9 and 6/12. A final myopic spherical equivalent −1.0 D was found in 14 out of 16 eyes.
CONCLUSIONS—A combination of PRK and PTK is effective in the alleviation of symptoms and prevention of recurrences of corneal erosion. It is suggested that recalcitrant recurrent corneal erosion is a diffuse disease, although it often manifests as a local problem, and therefore extensive excimer laser ablation is required to prevent recurrence and to alleviate symptoms completely.

     

Corneal aldehyde dehydrogenase and glutathione S-transferase activity after excimer laser keratectomy in guinea pigs

BACKGROUND—The free radical balance of the eye may be changed by excimer laser keratectomy. Previous studies have demonstrated that excimer laser keratectomy increases the corneal temperature, decreases the superoxide dismutase activity of the aqueous, and induces lipid peroxidation in the superficial corneal stroma. Aldehyde dehydrogenase (ALDH) and glutathione S-transferase (GST) are known to play an important role in corneal metabolism, particularly in detoxification of aldehydes, which are generated from free radical reactions.
METHODS—In three groups of guinea pigs mechanical corneal de-epithelialisation was performed in group I, superficial corneal photoablation in group II, and deep corneal photoablation in group III, and the corneal ALDH and GST activities measured after 48 hours.
RESULTS—The mean ALDH and GST activities of group I and II showed no differences compared with the controls (p>0.05). The corneal ALDH activities were found to be significantly decreased (p<0.05) and GST activities increased (p<0.05) in group III.
CONCLUSION—These results suggest that excimer laser treatment of high myopia may change the ALDH and GST activities, metabolism, and free radical balance of the cornea.

Keywords: excimer laser keratectomy; aldehyde dehydrogenase; glutathione S-transferase     

Correlation between central corneal thickness, applanation tonometry, and direct intracameral IOP readings

BACKGROUND—Several authors reported incorrect high intraocular pressure (IOP) values in eyes with a thick cornea using applanation tonometry. This hypothesis was checked by comparing applanation tonometry with direct intracameral manometry.
METHODS—73 patients, scheduled for intraocular surgery, were enrolled. Immediately before surgery, the following were registered: (i) central corneal thickness (CCT), (ii) applanatory IOP (Perkins/Tonopen), and (iii) intracameral IOP.
RESULTS—The difference between applanatory and intraocular measurements was completely independent of CCT (y=−3.43+3.8x; where y is the difference between applanatory and intracamerally measured IOP (mm Hg) and x is CCT (mm); r²=0.002; p=0.72).
CONCLUSIONS—There is no systematic error of applanation tonometry with increasing CCT. Therefore it is inadequate to recalculate IOP based on regression formula of applanatory IOP versus CCT.

     

Transplantation of congenitally opaque corneas

AIMS—To assess retrospectively the prognosis and complications of corneal grafting for congenital opacities.
METHODS—Fifty eight eyes of infants and young children with congenital corneal opacities were studied retrospectively. Preoperative diagnoses included sclerocornea (27 eyes), Peters' anomaly (17 eyes), partial sclerocornea (12 eyes), and congenital glaucoma (two eyes). Penetrating keratoplasty was performed between 5 days and 65 months of age with a mean follow up of 40 (SD 29) months.
RESULTS—The overall success (including regrafts) was 70% in eyes with sclerocornea, 83% for partial sclerocornea, and 100% for Peters' anomaly. However, 23 eyes had to be regrafted between 2 weeks and 110 months postoperatively. The probability of maintaining a clear graft, calculated by survival analysis, was 75% (SE 6%) at 1 year and 58% (7%) at 2 years for the entire group. Complications included cataract development (12 eyes), secondary glaucoma (14 eyes), epithelial defects (six eyes), band keratopathy (five eyes), retinal detachment (three eyes), wound leakage (two eyes), retrocorneal membrane (one eye), and microbial keratitis (two eyes).
CONCLUSIONS—It is concluded that corneal grafting for congenital opacities in infants has an excellent potential for long term survival and should be performed as early as possible for unilateral as well as bilateral involvement. The postoperative course is complex and often requires regrafting.

     

Corneal infiltration after recurrent corneal epithelial erosion

AIMS—To describe the clinical features of patients with a history of recurrent corneal epithelial erosion who develop acute corneal infiltration.
METHODS—The records were reviewed of patients who had previously been examined and treated for recurrent corneal epithelial erosion and who presented again with signs suggestive of a microbial keratitis.
RESULTS—11 patients were described; one patient presented with similar signs on two occasions. There was typically a paracentral epithelial defect >2 mm in diameter with an associated stromal infiltrate and an intense anterior uveitis. Three patients had a hypopyon, and four developed a subepithelial ring infiltrate. Samples were taken for microscopy and bacterial culture, with a positive isolate from two of 12 episodes (16%). Treatment with topical antibiotics and topical corticosteroid resulted in rapid re-epithelialisation and a reduction of inflammation. There was good visual outcome for all eyes, with a recurrence or symptoms of epithelial erosion in only one eye after a mean follow up period of 18 months.
CONCLUSIONS—Corneal infiltrates are an uncommon complication of recurrent corneal epithelial erosion. Despite the intensity of the infiltration the majority are culture negative using established techniques. There is typically rapid resolution and a good visual outcome, with a tendency for the episode to mark the end of further symptoms of epithelial erosion.

     

Effect of mycophenolate mofetil, cyclosporin A, and both in combination in a murine corneal graft rejection model

AIMS—To compare the effectiveness of mycophenolate mofetil (MMF), cyclosporin A (CSA), and both in combination, in preventing rejection following corneal transplantations.
METHODS—Rats of the inbred strains Brown Norway and Lewis were used as donors and recipients respectively. MMF was administered orally in both monotherapy and combination therapy for 14 days in a dosage of 40 mg/kg body weight, and CSA was administered, likewise for 14 days, in an intramuscular dosage of 10 mg/kg body weight. The transplants were examined every third day by slit lamp microscopy. Every transplant was subjected to histological or immunohistological evaluation.
RESULTS—The average transplant survival rate in the allogenic strain combination was 7.9 days (SEM 1.1). Monotherapy with MMF led to a statistically significant prolongation of transplant survival to 11.6 days (SEM 0.9, p< 0.05). Monotherapy with CSA delayed transplant rejection statistically significantly longer than MMF (21 days, 0.0, p< 0.05). The combination therapy with CSA and MMF was statistically significantly superior to the monotherapy with MMF (22.3 days, 0.5, p< 0.05). The combination therapy prolonged transplant survival compared with the CSA monotherapy, albeit not to a statistically significant extent.
CONCLUSIONS—In this study we were able to prove the immunosuppressive effect of oral MMF on acute rejection following corneal transplantation. Double drug therapy with CSA and MMF conferred a marginal benefit without a higher incidence of complications related to drug toxicity or overimmunosuppression.

Keywords: immunosuppressive agents; perforating keratoplasty