Degeneration and Regeneration of Subbasal Corneal Nerves after Infectious Keratitis: A Longitudinal In Vivo Confocal Microscopy Study

PURPOSE

To investigate the longitudinal alterations of subbasal corneal nerves in patients with infectious keratitis (IK) during the acute phase, cessation of treatment, and the recovery phase by in vivo confocal microscopy (IVCM).

DESIGN

Prospective, longitudinal, case-control, single-center study.

PARTICIPANTS

Fifty-six eyes of 56 patients with the diagnosis of bacterial (n=28), fungal (n=15), or Acanthamoeba (n=13) keratitis were included in the study. Thirty eyes of 30 normal volunteers constituted the control group.

METHODS

Corneal sensation and serial IVCM of the central cornea were performed prospectively using the Heidelberg Retina Tomograph 3/Rostock Cornea Module (Heidelberg Engineering, Heidelberg, Germany). The IVCM images were assessed at 3 time points: at the acute phase (first visit to the cornea service), at cessation of antimicrobial treatment, and up to 6 months after the resolution of infection.

MAIN OUTCOME MEASURES

Total nerve number and length, main nerve trunks, branching, and corneal sensation were assessed during the follow-up period.

RESULTS

Corneal nerves were reduced significantly during the acute phase in eyes with IK compared with controls across all subgroups, with total nerve length of 5.47±0.69 mm/mm2 versus 20.59±1.06 mm/mm2 (P<0.0001). At the cessation of treatment, corneal nerves in patients with IK had regenerated, including total nerve length (8.49±0.94 mm/mm2; P=0.02) and nerve branch length (4.80±0.37 mm/mm2; P=0.005). During the recovery phase, after resolution of infection, corneal nerves regenerated further, including total nerve length (12.13±1.97 mm/mm2; P=0.005), main nerve trunk length (5.80±1.00 mm/mm2; P=0.01), and nerve branch length (6.33±0.76 mm/mm2; P=0.003) as compared with the acute phase, but were still significantly lower when compared with controls (P<0.05 for all parameters). Corneal degeneration and regeneration correlated with corneal sensation (r=0.47; P=0.0009).

CONCLUSIONS

Patients with IK who sustain profound loss of corneal nerves during the acute phase of infection demonstrate increased corneal nerve density during the first 6 months after the resolution of infection. However, despite significant nerve regeneration, corneal nerve density does not recover fully and remains low compared to controls. By providing an objective methodology to monitor corneal re-innervation, IVCM adds potentially important findings that may have implications for clinical management and surgical planning.

[Evaluation of chemokines in tears of patients with infectious keratitis]

PURPOSE

To investigate the chemokine profile in tears of patients with infectious keratitis.

SUBJECTS AND METHODS

Subjects were 32 eyes of 16 patients with infectious keratitis and 5 eyes of 5 healthy volunteers as a control. The patients with infectious keratitis were classified into two groups of eyes: 10 with bacterial keratitis and 6 with Acanthamoeba keratitis. Tear fluid was obtained from both eyes of the patients with infectious keratitis and from the right eyes of the control subjects using filter paper. Chemokine concentration (unit: Odu/mm2) and its profile in tears was analyzed using an antibody-array.

RESULTS

In terms of chemokine profile in the bacterial keratitis group, the expression volume of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) in the diseased eyes was significantly higher than in the healthy eyes (p < 0.05). The expression volume of mucosae-associated epithelial chemokines (MECs) in the diseased eyes of the bacterial keratitis group was significantly lower than in the healthy eyes of that group (p < 0.05). In the Acanthamoeba keratitis group, chemokines were not significantly increased in the diseased eyes compared with those in the healthy eyes. However, MCP-1 was increased in tears of the Acanthamoeba keratitis group. Regarding the chemokine ratio, the IL-8/MEC ratio in the diseased eyes of the Pseudomonas keratitis group and the MCP-1/IL-8 in the diseased eyes of the Acanthamoeba keratitis group showed a significantly high level (p < 0.05).

CONCLUSION

We concluded that the analyses of the chemokine profile and chemokine ratio in the tears of infectious keratitis patients is useful as a clinical tear laboratory test to interpret the pathologic condition of infectious keratitis

Weight loss and reduced body temperature determine humane endpoints in a mouse model of ocular herpesvirus infection

Herpes simplex virus (HSV) has been studied in well-established mouse models to generate latently infected animals for investigations into viral pathogenesis, latency mechanisms, and reactivation. Mice exhibit clinical signs of debilitating infection, during which time they may become severely ill before recovery or die spontaneously. Because the cohort of mice that does survive provides valuable data on latency, there is keen interest in developing methodologies for earlier detection and treatment of severe disease to ultimately increase survival rates. Here, BALB/c mice were inoculated ocularly with either a wildtype (LAT(+)) or mutant (LAT(-)) strain of HSV1. Mice were monitored daily through day 30 after infection; trigeminal ganglia were harvested at day 60 to assess viral DNA load. Cages were provided with nesting material, and fluid supplementation was administered to mice with body temperatures of 35 °C or lower, as measured by subcutaneous microchip thermometry. The results showed that infected mice with temperatures less than 34.5 °C did not recover to normothermia and were euthanized or spontaneously died, regardless of infective viral strain. By using a combination of criteria including body temperature (less than 34.5 °C) and weight loss (more than 0.05 g daily) for removal of animals from the study, approximately 98% of mice that died spontaneously could have been euthanized prior to death, without concern of potential recovery to the experimental endpoint (100% specificity). Frequent monitoring of alterations to general wellbeing, body temperature, and weight was crucial for establishing humane endpoints in this ocular HSV model.

Role of miR-132 in angiogenesis after ocular infection with herpes simplex virus

MicroRNAs (miRNAs) are small regulatory molecules that control diverse biological processes that include angiogenesis. Herpes simplex virus (HSV) causes a chronic immuno-inflammatory response in the eye that may result in corneal neovascularization during blinding immunopathological lesion stromal keratitis (SK). miR-132 is a highly conserved miRNA that is induced in endothelial cells in response to growth factors, such as vascular endothelial growth factor (VEGF). In this study, we show that miR-132 expression was up-regulated (10- to 20-fold) after ocular infection with HSV, an event that involved the production of both VEGF-A and IL-17. Consequently, blockade of VEGF-A activity using soluble VEGF receptor 1 resulted in significantly lower levels of corneal miR-132 after HSV infection. In addition, low levels of corneal miR-132 were detected in IL-17 receptor knockout mice after HSV infection. In vivo silencing of miR-132 by the provision of anti-miR-132 (antagomir-132) nanoparticles to HSV-infected mice led to reduced corneal neovascularization and diminished SK lesions. The anti-angiogenic effect of antagomir-132 was reflected by a reduction in angiogenic Ras activity in corneal CD31-enriched cells (presumably blood vessel endothelial cells) during SK. To our knowledge, this is one of the first reports of miRNA involvement in an infectious ocular disease. Manipulating miRNA expression holds promise as a therapeutic approach to control an ocular lesion that is an important cause of human blindness.

Factors predicting unsuccessful big bubble deep lamellar anterior keratoplasty

PURPOSE

To evaluate the role of corneal structural resistance as a surgical failure factor in deep lamellar keratoplasty (DLK).

METHOD

A total of 10 eyes of 10 patients underwent DLK at the Ophthalmic Hospital in Rome. The big bubble technique was performed for deep stromal dissection by air injection. Seven patients were affected by advanced keratoconus and corneal thinning ranging from 441 to 235 microm. Two patients were affected by central corneal opacity from herpetic keratitis, and one patient suffered from corneal leucoma caused by bacterial keratitis. Clinical follow-up comprising final astigmatism and visual acuity findings were evaluated with a minimum follow-up of 12 weeks.

RESULTS

DLK was successfully performed in eight eyes, five of which were affected by moderate to advanced keratoconus and three by post-infective corneal opacity. In these patients preoperative ultrasonic pachymetry ranged between 441 and 287 microm. In the remaining two patients a perforation of the Descemet's membrane (DM) occurred while attempting to separate it from the overlying stroma by the big bubble technique, requiring a penetrating keratoplasty (PK) to be performed. In both cases preoperative ultrasonic pachymetry was below 250 microm. Both perforations occurred at a different site than the needle site and at the operative time of the big-bubble injection.

DISCUSSION

An ultrastructurally weakened DM may suffer a loss of resistance to a stressing force, becoming unable to tolerate the big bubble technique, and thus being perforated. Since the weakening of the DM is related to end-stage keratoconus corneal thinning, the preoperative corneal thickness rather than the surgeon's ability can play a major role in surgical failure of DLK. Our study reveals a very high risk of perforation of the DM when pre-operative total pachymetry is below limit of 250 microm.

Circulating anti-galectin-1 antibodies are associated with the severity of ocular disease in autoimmune and infectious uveitis

PURPOSE

Galectin (Gal)-1, an endogenous lectin found at sites of immune privilege, plays a critical role in the regulation of the immune response. Therapeutic administration of Gal-1 or its genetic delivery suppresses chronic inflammation in experimental models of autoimmunity. The purpose of this work was to investigate the occurrence of circulating anti-Gal-1 antibodies in patients with autoimmune and infectious uveitis as potential determinant factors of disease progression.

METHODS

IgG, IgE, and IgA anti-Gal-1 antibodies were assessed by ELISA and Western blot in sera from patients with autoimmune (n = 47) and infectious (n = 15) uveitis compared with healthy control subjects (n = 30). The frequency of anti-Gal-1 antibodies was examined in patients experiencing poor clinical outcome (n = 21) or good evolution (n = 9). Anti-Gal-1 antibodies were eluted by incubating patient sera with nitrocellulose filters adsorbed with rGal-1. The ability of these antibodies to recognize retinal tissue was assessed by ELISA, Western blot, and immunohistochemistry.

RESULTS

IgE, IgG, and IgA anti-Gal-1 antibodies were increased in sera from patients with autoimmune uveitis (P < 0.001 vs. controls) and toxoplasmic retinochoroiditis (P < 0.001). The level of anti-Gal-1 IgE and IgG antibodies was associated with progressive disease and poor outcome in autoimmune and infectious uveitis. Furthermore, these antibodies strongly immunoreacted with retinal lysates and recognized retinal structures mainly photoreceptors in retinal sections.

CONCLUSIONS

Anti-retinal Gal-1 antibodies are present in sera from patients with uveitis and can be associated with the progression of ocular disease, suggesting their potential use in follow-up observations of these patients.

Consequences of CXCL10 and IL-6 induction by the murine IFN-alpha1 transgene in ocular herpes simplex virus type 1 infection

Herpes simplex virus type 1 infection of the mouse eye results in an impressive inflammatory response culminating in the death of the animal or the establishment of a "latent" infection depending on a number of ill-defined variables that include components of the innate and adaptive immune system. The application of type I interferon transgenes has been found to antagonize viral replication and spread from the eye to the nervous system. Associated with the in situ transfection of the cornea is the upregulation of two inflammatory molecules, interleukin-6 and CXCL10. In this article, we will further examine the contribution these molecules may have in the host response to ocular infection with herpes simplex virus type 1.

Keratocyte loss in corneal infection through apoptosis: a histologic study of 59 cases

BACKGROUND

Keratocyte loss by apoptosis following epithelial debridement is a well-recognized entity. In a study of corneal buttons obtained from patients of corneal ulcer undergoing therapeutic keratoplasty, we observed loss of keratocytes in the normal appearing corneal stroma, surrounding the zone of inflammation. Based on these observations, we hypothesized that the cell loss in the inflammatory free zone of corneal stroma is by apoptosis that could possibly be a non-specific host response, independent of the nature of infectious agent.

METHODS

To test our hypothesis, in this study, we performed Terminal deoxyribonucleotidyl transferase-mediated d-Uridine 5" triphosphate Nick End Labelling (TUNEL) staining on 59 corneal buttons from patients diagnosed as bacterial, fungal, viral and Acanthamoeba keratitis. The corneal sections were reviewed for morphologic changes in the epithelium, stroma, type, degree and depth of inflammation, loss of keratocytes in the surrounding stroma (posterior or peripheral). TUNEL positivity was evaluated in the corneal sections, both in the zone of inflammation as well as the surrounding stroma. A correlation was attempted between the keratocyte loss, histologic, microbiologic and clinical features.

RESULTS

The corneal tissues were from 59 patients aged between 16 years and 85 years (mean 46 years) and included fungal (22), viral (15), bacterial (14) and Acanthamoeba (8) keratitis. The morphological changes in corneal tissues noted were: epithelial ulceration (52, 88.1%), destruction of Bowman's layer (58, 99%), mild to moderate (28; 47.5%) to severe inflammation (31; 52.5%). Morphologic evidence of disappearance or reduced number of keratocytic nuclei in the corneal stroma was noted in 49 (83%) cases; while the TUNEL positive brown cells were identified in all cases 53/54 (98%), including cases of fungal (19), bacterial (14), viral (13), and Acanthamoeba keratitis. TUNEL staining was located mostly in the deeper stroma and in few cases the peripheral stroma. TUNEL positivity was also noted with the polymorphonuclear infiltrates and in few epithelial cells (10 of 59, 17%) cases, more with viral infections (6/10; 60%).

CONCLUSIONS

We report apoptotic cell death of keratocytes in the corneal stroma in infectious keratitis, a phenomenon independent of type of infectious agent. The inflammatory cells in the zone of inflammation also show evidence of apoptotic cell death. It could be speculated that the infective process possibly triggers keratocyte loss of the surrounding stroma by apoptosis, which could possibly be a protective phenomenon. It also suggests that necrotic cell death and apoptotic cell deaths could occur simultaneously in infective conditions of the cornea.

Nucleotide-induced restoration of conjunctival chloride and fluid secretion in adenovirus type 5-infected pigmented rabbit eyes

We evaluated the role of extracellular UTP and other nucleotides in the regulation of chloride (JCl) and fluid secretion (JCl) across the pigmented rabbit conjunctiva. Jv was determined in freshly excised conjunctival tissues mounted between two buffer reservoirs maintained in an enclosed environment at 37 degrees C. Short circuit current (Isc) and 36Cl flux were measured using modified Ussing-type chambers. Fluid flux measurements were made with a pair of capacitance probes. After observing the baseline for 15 to 30 min, fluid flux was measured in the presence of mucosally applied nucleotides (10 microM) for a period of 30 min. Mucosal application of 10 microM each of UTP, UDP, ATP, ADP, AMP, adenosine, and ATP-gamma-S transiently stimulated fluid secretion across the conjunctiva to a significant extent for 10 to 15 min. Other nucleotides did not show any significant effect. The stimulation of fluid secretion correlated well with the stimulation in Isc (r2 = 0.85). UTP (0.1-1000 microM) led to a maximal increase in fluid secretion by 11.72 +/- 0.48 microl/(h x cm2) with an EC50 value of 10.39 +/- 1.08 microM. ATP (0.1-1000 microM) caused a maximal increase in fluid secretion by 11.89 +/- 0.88 microl/(h x cm2) with an EC50 value of 17.23 +/- 2.63 microM. Adenovirus type 5 (Ad5) infection significantly decreased both net 36Cl secretion across the conjunctiva by approximately 56% and the rate of fluid secretion by approximately 56%. UTP (10 microM), but not 1 mM 8-bromo-cAMP, was able to elicit a normal stimulatory response in the Ad5-infected tissues. In conclusion, mucosal application of purinergic nucleotides may be therapeutically important in restoring ion and fluid secretion in the diseased conjunctiva.

[Cat scratch disease with posterior segment involvement]

PURPOSE

To describe the clinical characteristics of patients with cat scratch disease during the last 2 years.

METHODS

Clinical characteristics and anterior and posterior segment manifestations were reviewed in five patients who were serologically diagnosed as having cat scratch disease.

RESULTS

Four women and one man were examined. Their ages ranged from 7 to 60 years. Each patient had a markedly elevated serum anti-Bartonella henselae antibody titer. Visual symptoms developed 2 weeks or less after the onset of systemic symptoms. Lymphadenopathy was detected in one of five patients. Neuroretinitis was found in 4 patients, and papillitis in 1 patient. Seven eyes showed retinochoroidal exudates. Anterior uveitis was observed in three eyes. Four patients received systemic corticosteroids.

CONCLUSION

The ocular manifestations of cat scratch disease include neuroretinitis, papillitis, retinochoroidal exudates, and anterior uveitis.

[Role of the vitreous body in vitreoretinal diseases]

Recent research during the last decades revealed evidence for the pathogenic role of the vitreous in many diseases of the retina. After a survey of the surgical anatomy and biochemistry of the vitreous, the author summarises present knowledge of various vitreoretinal disorders. Vitreoretinal disorders are discussed as follows: congenital anomalies, pathologic vitreoretinal adhesions, vitreous opacities, inflammatory diseases, vitreous hemorrhages and cellular infiltration of the vitreous. Special emphasis is placed on vitroretinal disorders of general importance, such as diabetic retinopathy, endogenous (fungal) endophthalmitis, Whipple disease, Crohn disease, sarcoidosis, shaken-baby syndrome, Terson syndrome, metastatic tumours of the choroid, cellular infiltration of the vitreous due to leukaemia or non-Hodgkin lymphoma, and amyloidosis. During the last few years better understanding of vitreoretinal disorders and improved diagnostic and therapeutic methods opened a new era of vitreoretinal surgery.

Current approaches to diagnosis and management of ocular lesions in human immunodeficiency virus positive patients

Human immunovirus infection in India is rapidly increasing. Ocular lesions due to highly active antiretroviral therapy have been well recognized. Acquired immunodeficiency syndrome can affect all parts of the eye. However, posterior segment lesions are the most common and of these, Human immunodeficiency virus retinopathy and cytomegalovirus retinitis predominate. Often clinical examination can establish the diagnosis of many ocular lesions in acquired immunodeficiency syndrome; therefore, ophthalmologists need to be aware of the more common ones. Various drugs in different routes can used to treat cytomegalovirus retinitis. Highly active antiretroviral therapy has remarkably reduced systemic and ocular morbidity among acquired immunodeficiency syndrome patients. To facilitate care of these patients aseptic precautions for ophthalmic care personnel are now well established and therefore ophthalmologist should not hesitate to provide ophthalmic care to acquired immunodeficiency syndrome patients.

Techniques for collection and interpretation of tissue samples in ocular disease

One of the keys to the accurate diagnosis of ocular disease is the appropriate selection and interpretation of ocular tissue samples. Without a good understanding of which test(s) to select and how to interpret test results, the clinician may arrive at an incorrect diagnosis and prescribe improper and/or ineffective therapy. This article outlines some of the more common ocular diagnostic procedures and gives guidance in the interpretation of test results.

Postmortem histological survey of the ocular lesions in a British population of AIDS patients

AIMS

To study ocular pathology and systemic correlations in a series of 73 postmortem eyes from British patients who died from AIDS before the introduction of a HAART regimen.

METHODS

The eyes were studied with conventional histology, special histochemical stainings, and immunohistochemistry.

RESULTS

72.6% of the cases showed chronic uveal inflammation, caused by opportunistic agents in 37.7% of them (cytomegalovirus (CMV) in 30.1%, C neoformans in 5.6%, and Gram positive bacteria in 1.8%). Cytoid bodies were noted in 10/73 eyes, three linked to CMV retinitis. Six retinal haemorrhages, four of which were secondary to CMV, were found. 14 specimens (19. 1%) showed foci of calcification, and a further 11 (15%) calcium oxalate deposits. In no cases were the calcific deposits suspected clinically. Six eyes (8.2%) did not show any abnormality.

CONCLUSIONS

CMV retinitis is the most common (28.7%, 21/73) ocular infection in this series and may occur either during or in the absence of systemic dissemination. Conversely, ocular cryptococcosis appears to be an epiphenomenon of systemic and CNS disease. No other opportunistic ocular infections were present in this series. Interesting findings were the presence of intraocular precipitates of calcium oxalate and calcium phosphate or carbonate in a significant number of cases (15% and 19%, respectively), and the high prevalence of idiopathic uveal inflammation (43.8%).

Twenty-five-year panorama of corneal immunology: emerging concepts in the immunopathogenesis of microbial keratitis, peripheral ulcerative keratitis, and corneal transplant rejection

PURPOSE

To describe the most recent advances in our understanding of the cellular and molecular mechanisms involved in the immunopathogenesis of corneal immunoinflammatory disorders including microbial keratitis, peripheral ulcerative keratitis. and allograft rejection.

METHODS

Review of the published peer-reviewed literature that has contributed significantly to our modern understanding of corneal immunology. In addition, the authors have summarized the information in conceptual diagrams that highlight the critical cellular and molecular pathways that lead to corneal immune responses in the two most thoroughly studied corneal immune disorders, herpes simplex keratitis (HSK) and transplant rejection.

RESULTS

In spite of the wide array of molecular and cellular factors that mediate corneal immunity, critical mechanistic facets are shared by the various corneal immunoinflammatory disorders. These include activation and migration of local antigen-presenting cells (APCs), including Langerhans cells (LCs), upregulation in pleiotropic proinflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor-alfa (TNF-alpha) that can mediate a wide array of immune functions in addition to up-regulating protease expression. and chemokines that play a critical role on the one hand in attracting nonantigen-specific inflammatory cells such as neutrophils and on the other in attracting CD4+ T helper type 1 (Th1) cells that mediate most of the destruction in the cornea.

CONCLUSIONS

In the last 25 years, we have seen our field develop from a descriptive stage into a new phase where the fundamental processes that mediate and effect corneal immunity are being accurately deciphered. It is anticipated that this new knowledge will allow development of specific molecular and genetic therapeutic strategies that could target critical steps in the immunopathogenesis of disease without the untoward side-effects of nonspecific generalized immune suppression that still remains the standard of care today.

Murine cytomegalovirus infection causes apoptosis of uninfected retinal cells

PURPOSE

To determine the role of apoptosis in prevention and/or exacerbation of retinal disease in a mouse model of cytomegalovirus retinitis.

METHODS

Immunocompetent or T-cell- depleted BALB/c mice were injected with murine cytomegalovirus (MCMV) by supraciliary injection. On sequential days after infection, mice were killed, and eyes were harvested for cryosectioning or for DNA extraction. Ocular sections were stained with monoclonal antibodies specific for MCMV or for T cells or used in the TdT-dUTP terminal nick-end labeling (TUNEL) assay to detect apoptotic cells.

RESULTS

In immunocompetent BALB/c mice, TUNEL assays revealed that a large area of the retina was apoptotic in relation to the relatively small number of MCMV-infected cells that were observed in the subjacent choroid and/or retinal pigment epithelium. In infected eyes from T-cell- depleted mice, there were more TUNEL-positive cells, and the areas of apoptosis were more extensive than in immunocompetent mice. These observations correlated with the increased extent of MCMV infection that is observed in the eyes of T-cell- depleted mice. However, irrespective of immune status, TUNEL-positive apoptotic cells were present mainly in areas of the retina overlying areas of MCMV-infected choroid and/or retinal pigment epithelium. More intense DNA laddering, indicative of increased apoptosis, was observed in the posterior segments of the eyes of T-cell- depleted mice after supraciliary inoculation with murine cytomegalovirus compared with less intense DNA laddering in the posterior segments of eyes of immunocompetent MCMV-infected mice.

CONCLUSIONS

The ability of the mouse's immune system to control MCMV infections in some tissues depends on induction of apoptosis in virus-infected cells. However, in the retina, cells undergoing apoptosis were not virus-infected, a finding that suggests that apoptosis of uninfected retinal cells may play a role in the pathogenesis of MCMV retinitis.

Risk factors for glaucoma filtering bleb infections

OBJECTIVE

To determine risk factors for bleb-related ocular infection after glaucoma filtering surgery.

METHODS

A case-control study comparing all consecutive cases of glaucoma filtering bleb-related infections (55 eyes of 55 patients) with matched control eyes between January 1, 1990, and June 30, 1998, was performed. Bleb-related infection was classified as blebitis when a mucopurulent infiltrate was identified within the bleb and associated with mild to moderate anterior segment inflammation. Eyes with endophthalmitis had hypopyon, cells in the anterior vitreous cavity, or a positive vitreous biopsy sampling result. A control was selected for each case based on matching of the surgeon, date and type of glaucoma surgery, and type of antifibrotic agent used. Multivariate, matched, case-control logistic regression analysis was performed using age, race, sex, diagnosis, number of previous incisional operations, filtering bleb location, and presence of bleb leak to determine which variables were associated with bleb-related infection.

RESULTS

The odds of an eye with a bleb-related infection being seen with a concomitant late-onset bleb leak are 25.8 times the odds of a noninfected eye having a late-onset bleb leak at any time in the postoperative period (P<.001; 95% confidence interval, 2.3-294.1). Other risk factors for bleb-related infection included younger age (P = .05), black race (P = .03), diagnosis of primary open-angle glaucoma (P = .03), and inferior location of the filtering bleb (P = .04).

CONCLUSIONS

Late-onset bleb leakage is a significant risk factor for bleb-related infection. The risk of infection may warrant closure of late-onset bleb leaks in selected eyes.

Clinical confocal microscopy

Because it provides much higher magnification and better optical sectioning than a slit-lamp biomicroscope, confocal microscopy is ideally suited for clinical imaging of the cornea. One important clinical application of confocal microscopy has been the early detection and diagnosis of a number of infectious conditions, including infection with Acanthamoeba and microsporidium species, fungal keratitis, and contact lens-associated bacterial keratitis. Confocal microscopy has also been used for temporal evaluation of corneal wound healing following refractive surgery and penetrating keratoplasty. With the development of the new technique of quantitative confocal microscopy through-focusing, confocal microscopy can be used to measure epithelial, stromal, and corneal thickness accurately and reproducibly in human patients. Furthermore, conofocal microscopy through-focusing can be used to determine the initial photoablation depth, changes in epithelial, stromal, and corneal thickness, and subepithelial haze following photorefractive keratectomy.

Endophthalmitis cluster from contaminated donor corneas following penetrating keratoplasty

OBJECTIVE

To attempt to identify common events or factors in four cases of endophthalmitis that developed after penetrating keratoplasty performed within a 1-week interval.

DESIGN

Case series.

SETTING

Tertiary care eye hospital in Riyadh, Saudi Arabia.

PATIENTS

Four patients in whom endophthalmitis developed after penetrating keratoplasty performed in May 1993.

OUTCOME MEASURES

Source of donor tissue, transportation of corneas, handling of corneas at the eye hospital, and causative organism and sensitivity profile.

RESULTS

The donor tissue in all four cases originated from the same eye bank. Organisms were cultured from 10 of the 11 donor rims from eye bank A tissue used during the week in question. The causative organisms were Enterococcus faecalis in three patients and Torulopsis glabrata in one patient. In each case the same organism was cultured from the recipient eye and the corresponding donor rim. Two of the four patients had a favourable outcome.

CONCLUSIONS

Donor rim culture is essential if the cause of endophthalmitis after penetrating keratoplasty is to be determined. Close communication between eye bank personnel, the microbiology laboratory and the operating surgeon is important as it may influence early detection, choice of treatment and outcome of endophthalmitis after penetrating keratoplasty. Epidemiologic studies from both the source eye bank and the recipient facility are required to fully investigate the cause of a cluster of endophthalmitis cases from contaminated donor tissue following penetrating keratoplasty.

Confocal microscopy as a tool for the investigation of the anterior part of the eye

In recent years, confocal microscopy has become a powerful tool for examining microscopic structures in the living eye. The decisive advantage of this technique is that it permits the investigation of optical sections of relatively thick (> 10 microns) specimens. Because confocal microscopy suppresses the out-of-focus blur, sharp three-dimensional images with excellent resolution can be obtained. Confocal microscopy is therefore able to provide more information than the classic methods--i.e., specular microscopy and slit-lamp biomicroscopy. This paper reviews recent applications of confocal microscopy in three fields of ophthalmology: the observation of the anatomy of the anterior parts of the eye, the investigation of these structures after local administration of drugs and, finally, the use of this technique for the diagnosis of infectious ocular diseases.

Consultation section. Refractive surgical problem

A 29-year-old Hispanic man who had bilateral radial keratotomy (RK) and astigmatic keratotomy (AK) in his right eye 1 year previously went swimming in a lake. He subsequently developed foreign-body sensation and pain with a gradual decrease in vision over the following 5 weeks, despite treatment with ciprofloxacin hydrochloride (Ciloxan) and diclofenac sodium (Voltaren). The patient sought a second opinion. On examination, best corrected visual acuity was 20/40 in the right eye and 20/20 in the left. Slitlamp examination revealed mild conjunctival and scleral injection and a 3.5 mm diameter stromal infiltrate densest at the edges (Figure 1). The infiltrate involved one RK and one AK incision with gaping of both, approximately 90% depth incisions (Figure 2). The anterior chamber was deep and quiet. Examination was otherwise unremarkable. The cornea was scraped, but the smears were negative. The Ciloxan and Voltaren were stopped, and scopolamine four times a day was started. Cultures for aerobic, anaerobic, fungal, acid-fast bacilli, and Acanthamoeba were performed but showed no growth in the following week. Except for vascular ingrowth, there was no change in the appearance of the microbial keratitis during this week. An incisional biopsy and rescraping were performed, but there was again no growth of micro-organisms and no change in the microbial keratitis in the following 4 days. How would you manage this patient at this time?

Ocular manifestation of systemic infections

Careful examination of external and internal ocular structures in patients with systemic infections may assist in early diagnosis and institution of appropriate therapy. Recent literature discussing ocular manifestations in the following systemic infectious diseases are reviewed: tuberculosis, Lyme borreliosis, cat scratch disease, toxocariasis, congenital toxoplasmosis, and invasive aspergillosis.

Clinicopathologic study of retinal and choroidal biopsies in intraocular inflammation

PURPOSE

We reviewed the clinical and histopathologic features of 33 intraocular tissue biopsy specimens from 32 patients and assessed the value of retinal and chorioretinal biopsies performed in patients with intraocular inflammation.

METHODS

Twenty-four endoretinal biopsies and nine chorioretinal or choroidal biopsies were performed. On the basis of clinical indications, the specimens were processed for light microscopy, electron microscopy, immunohistochemical staining, in situ DNA hybridization, and polymerase chain reaction.

RESULTS

Of the 24 endoretinal biopsy specimens, 19 were from patients with clinical signs suggestive of viral retinitis. Overall, the diagnosis of viral retinitis was suggested by electron microscopy, immunohistochemical staining, in situ DNA hybridization, or polymerase chain reaction in 53% (ten of 19) biopsies. The preoperative diagnosis was confirmed in seven of ten biopsies in cases of suspected cytomegalovirus retinitis, in one of seven biopsies in cases of suspected acute retinal necrosis, and in two of two biopsies in cases of progressive outer retinal necrosis. The remaining five endoretinal biopsies disclosed Candida in one specimen, subretinal fibrosis in one, and chronic inflammation in three. Histologic examination of the nine chorioretinal or choroidal biopsies disclosed lymphoma in two specimens, a subretinal neovascular membrane in one, uveal melanocytic proliferation in one, toxoplasmic retinochoroiditis in one, viral retinitis in one, and long-standing inflammation in three.

CONCLUSION

In select cases of intraocular inflammation, intraocular tissue biopsies may provide clinically useful information.

Non-CMV infectious chorioretinopathies in AIDS

Cytomegalovirus (CMV) retinitis is the most common posterior segment opportunistic infection and the leading cause of blindness in acquired immunodeficiency syndrome (AIDS) patients. CMV is not the sole agent that can infect the fundus of an immunocompromised patient. Disseminated herpes zoster (HZ), herpes simplex, toxoplasmosis, and Candidiasis are possible. Syphilis, Pneumocystis carinii, cryptococcosis, tuberculosis, and a host of other viruses, protozoa, bacteria, or neoplasms may invade the retina or choroid. The eye care practitioner must not only differentiate noninfectious retinopathy (AIDS retinopathy) from CMV retinitis, but also distinguish CMV retinitis from other posterior segment infections because the treatment modalities are different. This paper will review the clinical features of non-CMV infectious retinopathies and choroidopathies that occur in AIDS patients.

Lack of association between vitamin A status and measures of conjunctival epithelial integrity in young children in northern Ghana

OBJECTIVE

To investigate the association between vitamin A status and conjunctival epithelial function in young children in rural northern Ghana and to consider whether impaired epithelial function was associated with increased measures of systemic infection in these children.

DESIGN

Children were selected from the Ghana Vitamin A Supplementation Trials' Child Health Study, a randomized, double-blind, placebo-controlled trial of the effect of vitamin A supplementation on morbidity. Treatment group and serum retinol concentrations were used as measures of vitamin A status, conjunctival impression cytology and tear IgA concentrations as measures of conjunctival epithelial integrity, and serum immunoglobulin and alpha 1-acid glycoprotein concentrations as indicators of chronic or acute systemic infection.

SUBJECTS

Children 13-64 months old.

INTERVENTION

60 mg retinol as retinyl palmitate every 4 months for 1 year.

RESULTS

Vitamin A status was not significantly associated with epithelial integrity nor with measures of systemic infection. Impaired conjunctival epithelial integrity was also not associated with increased systemic infection.

CONCLUSIONS

There was no evidence for a major role of improved epithelial integrity and function on the biochemical indices of chronic or acute systemic infection after vitamin A supplementation. These data support the observations in the main study that vitamin A supplementation did not improve conjunctival impression cytology nor decrease the prevalence of most morbidity symptoms.

Retinochoroiditis in the acquired immune deficiency syndrome. Findings in consecutive post-mortem examinations

A number of opportunistic agents may cause retinitis or retinochoroiditis in patients with the acquired immunodeficiency syndrome. Minimal consecutive data is available on the histopathologically confirmed prevalence of these ocular infections. A total of 48 consecutive patients with acquired immunodeficiency syndrome-related death underwent autopsy and had their eyes submitted for histopathological examination. Conventional light microscopy combined with immunohistochemistry revealed cytomegalovirus retinitis in 15 patients, toxoplasma gonddi retinochoroiditis in 3 patients and mycobacterial choroiditis in one individual with some infections being coexistent. Clinical examination prior to death was highly accurate in detecting cytomegalovirus retinitis, but failed to determine all non-cytomegalovirus causes of retinochoroiditis. Ten of 15 patients with cytomegalovirus retinitis had associated non-cular cytomegalovirus infections, most often in the brain and adrenals. After clinical detection of cytomegalovirus retinitis the median survival time was 5.5 months, not adversely affected by additional non-ocular cytomegalovirus infection.

The eye in bone marrow transplantation. VI. Retinal complications

OBJECTIVE

To evaluate the posterior segment ocular complications of patients undergoing bone marrow transplantation (BMT).

DESIGN

Retrospective analysis.

SETTING

Academic ophthalmology department at a tertiary care hospital with a BMT unit.

PATIENTS

Patients undergoing BMT were seen by an ophthalmologist for clinical care and enrolled in a long-term follow-up study, during which they were seen 6 and 12 months after the transplantation and annually thereafter.

RESULTS

Of 397 patients undergoing BMT, 51 (12.8%) developed posterior segment complications. Fourteen patients (3.5%) developed hemorrhagic complications with either intraretinal and/or vitreous hemorrhages and 17 patients (4.3%) developed cotton-wool spots in the fundus of both eyes. Eleven patients (2.8%) had bilateral optic disc edema, with eight cases attributed to the toxic effects of cyclosporine and three to other causes. Two patients (0.5%) developed serious retinal detachments. Eight patients (2.0%) developed infectious retinitis and/or endophthalmitis. Fungal infections with Candida or Aspergillus usually occurred within 120 days after BMT, while viral infections with herpes zoster or cytomegalovirus and parasitic infections with Toxoplasma occurred later. Intraocular lymphoma occurred in one patient (0.2%).

CONCLUSION

Severe, potentially vision-threatening, posterior segment complications following BMT occur due to a variety of causes.

Adnexal findings in AIDS

We reviewed the adnexal and orbital findings in a large population with HIV infection followed in one medical center. Around 6% of the series had positive periocular findings. In 1% of the series, the periocular findings were the first manifestation of HIV infection or AIDS. We present the first case of basal cell carcinoma in an HIV-infected individual; the carcinoma involved the eyelid. Orbital findings included lymphoma, cellulitis, Kaposi's sarcoma, and nonspecific inflammatory disease. Adnexal findings included Kaposi's sarcoma, molluscum contagiosum, bacterial folliculitis, madarosis, psoriasis, basal cell carcinoma, and chalazion. Additional opportunistic infections and tumors involving the periocular region are expected to be reported in the future.

Ocular and periocular infections

In this article, the author emphasises the symptoms and signs of infections of the eye and their significance in establishing a diagnosis. Factors in the natural history and treatment that may modify the general practitioner's approach are indicated. Warning signs requiring immediate referral are highlighted.

[Rhinosporidiosis: presentation of 4 cases]

We report 4 cases of rhinosporidiosis in the province of Cáceres. Two had nasal localization and in two ocular conjunctiva was involved. Three patients, two of which came from the same village, had the antecedent of bathing in the same stagnant water. The diagnosis was made by the microscopic observation of characteristic sporangia of Rhinosporidium seeberi in the histopathological study. The lesions did not respond to antibiotic and antiinflammatory treatment. After excision there were no recurrences, and the patients are asymptomatic after 1 1/2 year follow up.