The outcome of corneal grafting in patients with stromal keratitis of herpetic and non-herpetic origin.

AIM: To evaluate the outcome of corneal grafting in patients with stromal keratitis of herpetic (HSK) and non-herpetic origin, using predefined diagnostic criteria and standardised postoperative therapeutic strategies. METHODS: 384 adult immunocompetent recipients of a corneal graft for herpetic (n = 186) or non-herpetic (n = 198) keratitis were followed up prospectively for up to 5 years. RESULTS: The herpetic group displayed significantly more corneal vascularisation (p = 0.013), more epithelial defects (p = 0.049), lower corneal sensitivity (p <0.001), more graft rejection episodes (p = 0.002), and required larger grafts (p<0.001). However, the postoperative course of visual acuity, endothelial cell numerical density, and rate of graft failures were similar in both groups. After 5 years, cumulative probability of graft survival in HSK patients (40.85%) was similar to that observed in individuals with non-herpetic keratitis (50.15%; log rank = 0.874; relative risk: 1.04). CONCLUSION: Despite a markedly higher preoperative risk profile in herpetic eyes, the functional outcomes of grafts in individuals with keratitis of herpetic or non-herpetic origin were similar. Probably the most important contribution is a consequent close follow up and a therapeutic strategy including systemic prophylaxis of viral recurrence and of graft rejection by well adopted local steroid therapy.

Real-time pachymetry during photorefractive keratectomy using optical low-coherence reflectometry.

Optical low-coherence reflectometry (OLCR) was used as a noncontact method to measure the central corneal thickness of three patients intraoperatively during photorefractive keratectomy. Continuous on-line measurements were performed on the intact cornea immediately before the beginning of surgery, after the removal of the corneal epithelium, during laser tissue photoablation, and for 3 min after the ablation process. Corneal thinning due to evaporation was studied on a separate patient with the OLCR instrument, and it was found to be -0.14 microm/s during the first 5 min after epithelium removal. This baseline corneal thinning rate was used as a fit parameter to calculate actual from measured ablation depths. The measurements showed a maximum difference of +/-10 microm between planned ablations (34-92 microm) and measured ablation depths.

Pentoxifylline influences the autocrine function of organ cultured donor corneas and enhances endothelial cell survival.

BACKGROUND/AIMS: Scientific interest in pentoxifylline has been reawakened owing to the recognised effects of this drug on immune functions, particularly its influence on cytokine production. In a previous study, the authors demonstrated that spiking of organ culture media with endotoxin elicited a marked enhancement in the release of IL-6 and IL-8 from corneal tissue and that these events coincided with degenerative changes in endothelial cells and a higher incidence of actual loss among this population. Since traces of donor derived endotoxin can be detected in up to 50% of corneal organ cultures, this substance may have a direct influence on graft viability or trigger inflammatory responses in the host. They, therefore, wished to ascertain whether supplementation of media with pentoxifylline improved endothelial cell survival in organ cultured donor corneas. METHODS: 12 fellow pairs of donor corneas were cultured for 20 days, with a change of medium on day 10: One of each pair was incubated in the absence, and the other in the presence, of pentoxifylline (25 microg/ml). Samples of medium were withdrawn at regular intervals during the course of incubation and screened for cytokines IL-6, IL-8, and prostaglandin E2 by ELISA. Endothelial cell morphology and numerical density were assessed on days 0, 10 and 20. RESULTS: Addition of pentoxifylline to organ culture media led to a significant improvement in endothelial cell survival. This drug also elicited a significant increase in the level of IL-6 and marginally suppressed that of IL-8 during the initial 10 day phase of incubation. During the second 10-20 day phase, the level of both IL-6 and IL-8 decreased significantly in the presence of pentoxifylline, the relation between these two cytokines being the inverse of that observed in the absence of the drug. No significant changes in the level of prostaglandin E2 were apparent. CONCLUSION: The addition of pentoxifylline to organ culture media leads, ultimately, to a suppression of IL-6 and IL-8 secretion by corneal tissue. The potentially damaging effects of these cytokines are thereby quelled, as evidenced by the improvement in endothelial cell survival.

Morphology of the stromal surface and endothelium using two different microkeratomes.

PURPOSE: To compare stromal surface and endothelial morphology after keratectomies and after laser in situ keratomileusis (LASIK), using two different microkeratomes. METHODS: Keratectomies (160-microm and 400-microm) were performed on 82 enucleated porcine eyes using the Chiron Automated Corneal Shaper (52 eyes) and the Microtech Turbokeratome (30 eyes). LASIK procedures of -9.00 D, -27.00 D, and -36.00 D were performed with a Schwind excimer laser. The corneas were immediately fixed in glutaraldehyde or stained with alizarin red and trypan. Scanning electron microscopy was then performed. RESULTS: All keratectomies performed with the Chiron microkeratome displayed a relatively smooth surface. The quality of the keratectomies with the manually advanced Microtech microkeratome was variable, with a high incidence (4 of 9) of incomplete cuts and irregular surfaces. In the eyes in which the stromal laser ablation was performed, a thin layer of condensed stroma (pseudomembrane formation) was seen. Vital staining did not indicate endothelial damage. CONCLUSIONS: The surface morphology was unacceptable for one of the microkeratomes tested. Keratectomies of 160 to 400 microm and LASIK up to -36.00 D did not acutely alter endothelial morphology in porcine eyes.

Central corneal thickness measurements in patients with normal tension glaucoma, primary open angle glaucoma, pseudoexfoliation glaucoma, or ocular hypertension.

BACKGROUND/AIMS: Recent studies have revealed patients with ocular hypertension to have thicker than normal central corneas and those with normal tension glaucoma to have thinner than normal ones, as determined by ultrasonic pachymetry. Since corneal thickness measurements and applanation tonometric estimates of intraocular pressure (IOP) correlate positively, monitoring of the former parameter have served as the basis for adjusting readings pertaining to the latter, with the consequence that many patients have had to be reclassified. With a view to validating these pachymetric studies, the central corneal thickness was determined in patients with normal tension glaucoma, primary open angle glaucoma, pseudoexfoliation glaucoma, or ocular hypertension, as well as that of normal subjects, using optical low coherence reflectometry, which is a new and more precise method than ultrasonic pachymetry. METHODS: 34 patients with normal tension glaucoma, 20 with primary open angle glaucoma, 13 with pseudoexfoliation glaucoma, and 12 with ocular hypertension, together with 21 control subjects, were included in this observational, concurrent case-control study. One eye per individual was randomly selected for investigation. IOP was measured by Goldmann applanation tonometry and central corneal thickness by optical low coherence reflectometry. RESULTS: Central corneal thickness was significantly higher (p < or =0.001) in patients with ocular hypertension than in normal individuals or in subjects with either normal tension glaucoma, primary open angle glaucoma, or pseudoexfoliation glaucoma, there being no significant differences between the latter four groups. Patients with ocular hypertension were also significantly younger (p < or =0.003) than those within any of the three glaucomatous groups. CONCLUSION: This study confirms that a significant number of patients with ocular hypertension have normal IOPs after the appropriate adjustments have been made for deviations from normal in their central corneal thickness. The accurate measurement of this latter parameter is important not only for individual patient care, in permitting more precise estimations of IOP, but also for clinical studies, in assuring a more reliable classification of subjects.

Three-dimensional confocal microscopy of the human cornea in vivo.

This paper reviews the literature from 1990 to 2000 and evaluates the seminal investigations performed with the confocal microscope on the in vivo human cornea. Our pedagogical technique is to illustrate both the advantages and the problems associated with occular confocal microscopy by way of annotated examples. Confocal microscopy offers improved resolution and has resulted in new discoveries of corneal pathology at the cellular level. The ability to provide high-resolution, real-time images of the full thickness of the cornea gives the clinician and the researcher an important new tool for the investigation of the cornea.

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.

Confocal microscopy of the human cornea in vivo.

In vivo, scanning-slit, confocal microscopy offers improved resolution and has resulted in new discoveries of corneal pathology at the cellular level. The ability to provide high resolution, real-time images of the full thickness of the living human cornea gives the clinician and the researcher an important new tool.

Confocal microscopy after implantation of intrastromal corneal ring segments.

OBJECTIVE: Confocal in vivo real-time microscopy was used to study the corneal morphologic features in eyes after Intrastromal Corneal Ring Segments (ICRS; now called KeraVision INTACS, KeraVision, Inc., Fremont, CA) implantation. DESIGN: Noncomparative, interventional case series. PARTICIPANTS: The authors performed confocal real-time microscopy on a total of 21 eyes from 11 patients. Seventeen eyes from 10 patients (five female, five male; mean age 32.3 years; range 22-42 years) underwent uncomplicated ICRS surgery to correct myopia and were examined after surgery (average 8.6 months; range 2-15 months). Three patients had the ICRS implanted into only one eye, and those eyes were compared with the untreated fellow eyes. One eye of another patient was examined 1 and 6 months after ICRS removal. INTERVENTION: Flying slit-confocal microscopy was performed with water immersion objectives in the corneal center and near the nasal or temporal ICRS. Corneal optical sections were recorded in real time without further digital processing and were reviewed frame by frame. MAIN OUTCOME MEASURES: Video frames selected from all corneal layers were evaluated qualitatively and quantitatively. RESULTS: In the central cornea, we found normal morphologic features at all layers. In peripheral sections, epithelial cells with highly reflective nuclei in the basal cell layer were observed in six of 17 eyes (35%) implanted with ICRS. We found an intact corneal nerve plexus and undisturbed corneal endothelium immediately underneath the ICRS. Around the ICRS, moderate fibrosis was seen. In one eye, linear structures in bamboo-like orientation were detected after ICRS removal in the last keratocyte layer underneath the collapsed tunnel. CONCLUSIONS: Whereas the central corneal zone appears unchanged, the corneal stroma adjacent to the ICRS displays a slight, but distinct, activation of wound healing. Epithelial cells with highly reflective nuclei in this region may be an indicator for an increased biologic stress caused by the device.

Treatment of postkeratitis fusarium endophthalmitis with amphotericin B lipid complex.

PURPOSE: The authors report the first case of Fusarium solani keratitis that progressed to fungal endophthalmitis and was successfully treated with amphotericin B lipid complex (ABLC). METHOD: The case of a 34-year-old immunocompetent woman who developed a contact lens-related F. solani keratitis requiring emergency penetrating keratoplasty (PKP) was analyzed. The immunocompetent patient developed fungal endophthalmitis (anterior chamber tap positive for F. solani three months after PKP) and was eventually treated with ABLC. RESULTS: Systemic amphotericin B (total, 0.42 g) and ketoconazole in addition to topical natamycin and amphotericin did not prove to be effective in eradicating the mycosis in the anterior chamber. Under ABLC treatment (total, 8.79 g), the anterior chamber inflammation resolved completely. No recurrence was observed during an 11-month follow-up after treatment was discontinued. CONCLUSION: ABLC proved to be effective in treating F. solani endophthalmitis. It is an important addition to the ophthalmic armamentarium, and appeared to be a better therapeutic agent than standard amphotericin B in this patient.

[Nocturnal measurements of intraocular pressure in patients with normal-tension glaucoma and sleep apnea syndrome]. / Nächtliche Messungen des Intraokulardrucks bei Patienten mit Normaldruckglaukom und Schlaf-Apnoe-Syndrom.

BACKGROUND: About half of all normal-tension glaucoma patients and about one third of all primary open-angle glaucoma patients have sleep apnea syndrome. If sleep apnea syndrome causes some cases of glaucoma, the optic nerve damage could result from repetitive nocturnal hypoxias or from repetitive intraocular pressure elevations at the end of the apneas. In this study, we determined the intraocular pressure at the end of long apneas. PATIENTS AND METHODS: In three patients having sleep apnea syndrome and normal-tension glaucoma we recorded in a sleep laboratory during at least six hours of sleep the respiration (oxymetry, nasal and oral air flow, and inductive plethysmography). The intraocular pressure was measured with a pneumatonometer at predetermined times and compared to the values measured at the end of prolonged apneas. RESULTS: The intraocular pressure during normal respiration was in the first patient 19.5 +/- 1.0 mm Hg OD and 19.3 +/- 1.7 mm Hg OS, in the second patient 25.0 +/- 4.2 respectively 25.5 +/- 4.9 mm Hg and in the third one 22 +/- 1.0 respectively 21.3 +/- 1.3 mm Hg. At the end of prolonged apneas the intraocular pressure was in the first patient 19.0 +/- 0.0 mm Hg OD and 19.5 +/- 0.7 mm Hg OS, in the second patient 26.5 +/- 0.6 and 26.8 +/- 0.1 mm Hg and in the third one 20.0 +/- 0.0 respectively 21.0 +/- 0.0 mm Hg. The difference between intraocular pressures during normal respiration and at the end of prolonged apneas was not significant (p > 0.1 for each comparison, paired t-test). CONCLUSIONS: We did not find an increase of intraocular pressure at the end of prolonged apneas compared to periods of normal respiration in patients with sleep apnea syndrome and normal-tension glaucoma. If sleep apnea syndrome causes some cases of glaucoma, it seems more probable that the the optic nerve is damaged by the repetitive hypoxias. Alternatively, an unknown factor might induce both, sleep apnea syndrome and normal-tension glaucoma.

Prospective, randomized clinical evaluation of Optisol vs organ culture corneal storage media.

OBJECTIVE: To compare the outcome of penetrating keratoplasty with the use of corneas stored either in Optisol (Chiron Ophthalmics, Irvine, Calif) or in organ culture. METHODS: Penetrating keratoplasty was performed on 12 pairs of patients matched by age and diagnosis. Each pair of procedures was done on the same day by the same surgeon using the same technique. Twelve pairs of corneas were used. One cornea of each pair had been stored in organ culture at 36 degrees C and one in Optisol at 4 degrees C. Mean (+/-SD) storage time was 6+/-3 days. Mean endothelial cell density before storage was 2617/mm(2) for the corneas in organ culture and 2624/mm(2) for the corneas in Optisol. Examinations were performed at 1, 4, 12, and 24 months. RESULTS: One reversible rejection occurred in the Optisol group. At 1 month the mean endothelial cell density was 2327+/-341/mm(2) for the organ culture group and 2240+/-504/mm(2) for the Optisol group. At 12 months the difference was more pronounced (2225+/-410 and 2103+/-466/mm(2), respectively), although statistically not significant. Corneal thickness also did not show any statistically significant difference. CONCLUSION: Penetrating keratoplasty performed with corneas stored for a maximum of 11 days in either Optisol or organ culture show similar outcomes in the first 2 postoperative years. Arch Ophthalmol. 2000;118:757-760

Primary open-angle glaucoma is associated with sleep apnea syndrome.

INTRODUCTION: The etiology of primary open-angle glaucoma remains unclear. Various risk factors, including vascular abnormalities, have been associated with this disease. Sleep-associated diseases, like sleep apnea syndrome, might also represent a risk factor. Sleep apnea syndrome is characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption with the risk of cardiovascular and neurological sequelae. In this study, we determined the prevalence of sleep apnea syndrome in primary open-angle glaucoma patients. METHODS: Overnight transcutaneous finger oximetry was performed in 30 consecutive patients having primary open-angle glaucoma. We assessed the oximetry disturbance index during night sleep, a parameter used to diagnose sleep apnea syndrome and to grade its severity. RESULTS: Sleep apnea syndrome was more prevalent among primary open-angle glaucoma patients compared to normal historic controls of the same age and sex distribution (chi(2) = 9.35, d.f. = 3, p < 0.025). The oximetry disturbance index grade was significantly larger in the primary open-angle glaucoma group compared to normal controls (U = 3, 352, p = 0.01). According to the oximetry disturbance index, 20% (6/30) of primary open-angle glaucoma patients had sleep apnea syndrome. CONCLUSION: Primary open-angle glaucoma is associated with sleep apnea syndrome. Early recognition and treatment of sleep apnea syndrome are important to avoid cardiovascular and neurological complications.

Topical rivastigmine, a selective acetylcholinesterase inhibitor, lowers intraocular pressure in rabbits.

Non-selective acetylcholinesterase (AChE) inhibitors are known hypotensive agents. The purpose of the present investigation was carried out to ascertain whether rivastigmine, a selective carbamate-type inhibitor of AChE, which inhibits selectively an isoform of this enzyme found almost exclusively in the central nervous system, is able to depress the intraocular pressure (IOP) in normotensive rabbits. IOP was monitored with a TonoPen XL in conscious adult rabbits before and hourly up to 8 hr after administration of the drug. Baseline measurements without treatment and after one single topical application of rivastigmine [1% (n=8); 2% (n=4); and 5% (n=6)] to the right eye and of the vehicle alone to the left one were performed. Rivastigmine reduced the IOP of treated eyes significantly (p<0.05) in a dose-independent manner. Maximal effects of 23.2% (5% rivastigmine), 19.6% (2% rivastigmine) and 15.2% (1% rivastigmine) were achieved 1, 3 and 5 hr after application of the drug. A non-significant reduction of IOP in the contralateral eye was also observed. Rabbits evidenced no signs of discomfort after administration of rivastigmine. No conjunctival discharge or other signs of drug related local toxicity were found. Rivastigmine, a selective antagonist of AChE, lowers IOP significantly and may thus be of potential use in glaucoma therapy.

Toxicity of pentoxifylline on monolayers of highly proliferative cells of epithelial origin.

Interest in pentoxifylline has been recently reawakened owing to its suppressive effect on cell cytokine production. In this capacity, it may be of value as a routine supplement for culture media containing donor corneas. The purpose of the present study was to evaluate the toxic effects of pentoxifylline on two standardized cell lines of epithelial origin. Vero and Chang cells were incubated with various concentrations of pentoxifylline. Acute toxicity (4 hr) was assessed by monitoring the permeability of cells to propidium iodide; chronic toxicity (7 days) was determined by monitoring the effect of pentoxifylline on esterase activity and cell proliferation. The viability of cells was also assessed by microscopic inspection. Signs of acute toxicity became manifest at a pentoxifylline concentration of 100 mg/l in both Chang and Vero cells. Indications of chronic toxicity were observed at a drug concentration of 10 mg/l in Chang cells but at 1 mg/l in Vero ones. Proliferation was suppressed at pentoxifylline concentrations of 100 mg/l and 10 mg/l in Chang and Vero cells, respectively. Degenerative morphological changes were observed at a drug concentration of 100 mg/l in both cell types. At a concentration of 0.1 mg/l, pentoxifylline elicited no signs of acute or chronic toxicity in either Chang or Vero cells. At this dose, the drug is therefore unlikely to have deleterious effects on cultured donor corneas.

Evaluation of phacotrabeculectomy versus trabeculectomy alone.

Our purpose was to evaluate phacotrabeculectomy (PT) versus trabeculectomy alone (TA). 161 eyes with primary open angle or pseudoexfoliative glaucoma operated on consecutively by one surgeon were followed prospectively. 1 year follow-up was available for 70 eyes with PT and 54 with TA (77% of all eyes). Intraocular pressure (IOP) in PT dropped from 23.4 +/- 8.9 to 13.3 +/- 3.4 mm Hg and in TA from 24.8 +/- 7.5 to 14.2 +/- 3.9 mm Hg. IOP difference between PT and TA at 1 year was nonsignificant (p > 0.1). The average number of medications in PT dropped from 1.9 +/- 0.9 to 0.1 +/- 0.5 and in TA from 2.2 +/- 0.9 to 0.3 +/- 0.6 (p > 0.1). We conclude that additional phacoemulsification does not influence intraocular pressure control at 1 years.

Morphological and functional analysis of immortalized human corneal endothelial cells after transplantation.

Approximately 50% of donor corneas are unsuitable for keratoplasty due to an unacceptably low endothelial cell count. One way of overcoming this problem and minimizing wastage of donor corneas may be to transplant cultured human corneal endothelial cells onto these. In this study, we examined the morphological characteristics and functional attributes of endothelial layers formed after the transplantation of immortalized cells in vitro. Cultured human corneal endothelial cells, immortalized by transfection with a plasmid encoding SV40 T-antigen, were seeded onto human corneas denuded of their own endothelium. Seven days after transplantation the newly established monolayers were examined by light, confocal and scanning electron microscopy. Endothelial pump function was gauged by monitoring changes in corneal thickness during perfusion of the endothelial face. The endothelia formed from transplanted immortalized cells had a cobblestone-like appearance, being composed of polygonal units joined by junctional complexes. The stromal hydration state of corneas bearing such endothelial layers could be controlled during perfusion. This was an active process achieved via the Na(+)/K(+)-ATPase-dependent endothelial pump, as demonstrated by inhibiting the enzyme with ouabain. Transplantation of immortalized human corneal endothelial cells onto recipient corneas led to the establishment of new monolayers which had the morphology of the native ones in organ-cultured corneas. This model provides us with a means of studying the formation and function of corneal endothelial layers in vitro.

In vivo confocal microscopy of fleck dystrophy.

PURPOSE: To use in vivo confocal microscopy to evaluate corneas with fleck dystrophy. METHODS: Both eyes of three patients with corneal fleck dystrophy were examined with a scanning slit confocal microscope. Corneal epithelium, stroma, and endothelium were evaluated, as well as the basal epithelial and stromal nerves. RESULTS: The epithelium did not show any anomalies, but the basal nerves showed hyperreflective inclusions. Throughout the entire stroma, hyperreflective dots of various shapes were seen. These consisted mostly of spherical matter with a diameter of 3-5 microm and were sometimes enclosed in cyst-like structures. The majority of the stromal cells and stromal nerves appeared normal. The endothelial cell layer was unaffected. CONCLUSION: In vivo confocal microscopy demonstrates previously unreported inclusions in the basal nerves of fleck dystrophy corneas. In addition to this new finding, the study confirms earlier histopathologic reports, demonstrating accumulation of pathologic material in the stromal cells.