Characterization of epithelial downgrowth by confocal microscopy.

A 43-year-old white woman with a history of multiple ocular surgeries, including 4 penetrating keratoplasties, developed a concentric retrocorneal membrane at the graft periphery in the right eye. A white-light, tandem, scanning confocal microscope using a 24x/0.60 contact objective was used to examine the right eye in vivo. At the endothelial layer, confocal microscopic images similar to corneal epithelial cells were detected at the graft periphery. Unlike normal endothelial cells, the imaged cells demonstrated easily recognizable nuclei.

Confocal microscopy in lattice corneal dystrophy.

BACKGROUND: The purpose of the study was to assess the appearance of lattice corneal dystrophy by means of white-light confocal microscopy. METHODS: Two consecutive patients with lattice corneal dystrophy were prospectively examined. In vivo white-light tandem-scanning confocal microscopy was performed in the right eye of the first patient. Her left eye had undergone penetrating keratoplasty 4 years earlier. Histologic findings of the corneal button were compared with confocal microscopic findings of the right eye. The other patient was monocular and confocal microscopy was performed only in the non-seeing eye. RESULTS: In both patients, linear and branching structures with changing reflectivity and poorly demarcated margins were visualized in the stroma. The linear structures measured approximately 40-80 microm in width. CONCLUSION: Lattice corneal dystrophy presents characteristic linear images on confocal microscopy and should not be misdiagnosed as fungal hyphae in cases of corneal infection.

Confocal microscopy in posterior polymorphous corneal dystrophy.

PURPOSE: To report the distinguishing characteristics of posterior polymorphous corneal dystrophy (PPMD) using confocal microscopy. MATERIAL AND METHODS: Two consecutive patients with PPMD were prospectively examined using a white-light tandem scanning confocal microscope with a 24x/0.60 contact objective. RESULTS: At the level of Descement's membrane, roundish hyporeflective images were found in 1 patient. In the other patient, hyporeflective bands were detected. In both patients, patchy hyperreflective areas were identified. CONCLUSION: Confocal microscopy may allow diagnosis of PPMD by demonstrating the alterations in Descement's membrane. This technique is especially valuable in cases of endothelial decompensation, where slit-lamp and specular microscopy may fail to demonstrate changes in Descement's membrane.

Corneal thickness measurements with the Topcon SP-2000P specular microscope and an ultrasound pachymeter.

OBJECTIVE: To compare the reproducibility of measurements obtained with a new pachymetry instrument, the Topcon specular microscope (Topcon SP-2000P; Topcon America Corp, Paramus, NJ), with those obtained by ultrasound pachymetry. METHODS: Corneal thickness was measured in 40 eyes of 40 patients 3 times each with the Topcon SP-2000P and an ultrasound pachymeter (DGH 500, DGH Technology Inc, Exton, Pa) by 2 separate investigators. Comparisons included average thickness as measured by each instrument, average thickness for each instrument as measured by each investigator, and differences in thickness due to corneal abnormalities. RESULTS: Mean corneal thickness measured by the Topcon instrument was significantly less (32 microm; P<.001) than the mean value obtained with the ultrasound pachymeter. Similarly, mean values obtained with the 2 instruments by the 2 investigators were significantly different (P<.001 and .008 for investigators 1 and 2, respectively), with the Topcon value less than the ultrasound value in both cases. Both instruments detected abnormalities in corneal thickness equally well. However, the measurements obtained with the Topcon instrument by the 2 investigators were more consistent (no significant difference [P=.32]) than those obtained with the ultrasound unit (difference was significant [P=.02]). CONCLUSIONS: The new noncontact Topcon specular microscope provides measurements of corneal thickness that are somewhat less than those of ultrasound pachymetry, but that seem to be more consistent from one operator to another, possibly as a result of the elimination of observer bias induced by probe placement required by the ultrasound unit. This consistency may be important in the comparison of measurements by different operators over time in patients being followed up after refractive surgery or other therapeutic interventions.

Confocal microscopy in cornea guttata and Fuchs' endothelial dystrophy.

AIMS: To report the appearances of cornea guttata and Fuchs' endothelial dystrophy from white light confocal microscopy. METHODS: Seven eyes of four consecutive patients with cornea guttata were prospectively examined. Of the seven eyes, three also had corneal oedema (Fuchs' dystrophy). In vivo white light tandem scanning confocal microscopy was performed in all eyes. Results were compared with non-contact specular microscopy. RESULTS: Specular microscopy was precluded by corneal oedema in one eye. In the remaining six eyes, it demonstrated typical changes including pleomorphism, polymegathism, and the presence of guttae appearing as dark bodies, some with a central bright reflex. In all seven eyes, confocal microscopy revealed the presence of round hyporeflective images with an occasional central highlight at the level of the endothelium. Changes in cell morphology and size were readily appreciated. CONCLUSION: By comparison with specular microscopy, the hyporeflective images with an occasional central highlight seen on confocal microscopy are consistent with the presence of guttae. Confocal microscopy may confirm the diagnosis of cornea guttata and Fuchs' endothelial dystrophy by demonstrating the presence of guttae. This technique is especially valuable in cases of corneal oedema, where specular microscopy may fail to visualise the endothelium. However, specular microscopy should remain the method of choice to evaluate the endothelium, principally because it is easier to use.

Confocal microscopy in the iridocorneal endothelial syndrome.

AIMS: To report the appearances of iridocorneal endothelial (ICE) syndrome from real time, white light confocal microscopy. METHODS: Three consecutive patients, each with ICE syndrome, were examined prospectively. Corneal specular and confocal microscopic examinations were performed in all three patients. In the first patient, a penetrating keratoplasty was performed and the cornea was examined by light and scanning electron microscopy. No surgery was performed in the remaining two patients. RESULTS: In the first patient corneal oedema prevented endothelial specular microscopy. Confocal microscopy performed before penetrating keratoplasty successfully revealed abnormal epithelial-like endothelial cells. Histological examinations of the cornea following penetrating keratoplasty revealed the presence of multilayered endothelial cells with epithelial features (microvilli). In the remaining two patients, specular microscopy showed the presence of ICE cells with typical dark/light reversal. Confocal microscopy demonstrated groups of endothelial cells with epitheloid appearances. In all three patients, the contralateral endothelial appearance was normal by specular and confocal microscopy, except for moderate endothelial polymegathism in one patient. Epithelial-like endothelial cells were characterised by prominent nuclei on confocal microscopy. CONCLUSIONS: The application of confocal microscopy indicates that the ICE syndrome is characterised by epitheloid changes in the endothelium. Confocal microscopy may be used to diagnose the ICE syndrome by demonstrating epithelial-like endothelial cells with hyperreflective nuclei. This technique is especially of value in cases of corneal oedema, since specular microscopy may fail to image the endothelium in such cases.

Differential diagnosis of linear corneal images on confocal microscopy.

PURPOSE: This study aimed to detect corneal conditions presenting with linear images on white light confocal microscopy and to analyze their distinguishing characteristics. METHODS: In 1996 and 1997, 153 eyes of 110 patients with various corneal conditions were examined. In vivo examination of the cornea was performed by using a white-light tandem scanning confocal microscope. Images were captured by using a video camera and stored on S-VHS video tapes. In this retrospective study, patient charts and confocal microscopic video records were reviewed. Conditions with linear images were looked for, and the images were analyzed and compared. RESULTS: The only structures presenting as linear images on confocal microscopy in normal subjects consisted of corneal nerves. The following pathologic conditions also had linear images on confocal microscopy: corneal vascularization, mycotic keratitis, lattice corneal dystrophy, and posterior polymorphous dystrophy. Each condition could be identified based on its reflectivity, delineation, size, branching pattern, and location in the cornea. CONCLUSION: Different corneal conditions present with linear images on confocal microscopy. Correct identification is critical to avoid misdiagnosis.

Interface inflammation after laser in situ keratomileusis. Sands of the Sahara syndrome.

PURPOSE: To determine the source of the interface debris that causes the interface inflammation known as "sands of the Sahara" after laser in situ keratomileusis (LASIK). SETTING: Department of Ophthalmology, LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans, USA. METHODS: A microkeratome (Automated Corneal Shaper) was used to make a LASIK flap in 8 eyes of 4 rabbits. In 4 eyes, the blade was used directly from the sterile pack; in the contralateral 4 eyes, the blade was cleaned prior to use. In vivo confocal microscopy of the corneas was performed 1 day after surgery. An unused, cleaned blade and an unused, uncleaned blade, as well as blades used in the rabbit eyes, were examined by scanning electron microscopy. RESULTS: Confocal microscopy revealed numerous fragments of debris surrounded by inflammatory cells in the LASIK flap interfaces created by blades taken directly from the sterile package. Interfaces created by the cleaned blades showed only rare, scattered bits of debris. Scanning electron microscopy of the unused blades showed debris on the uncleaned blade removed directly from the sterile package. CONCLUSION: Post-LASIK interface inflammation may be caused by debris on the microkeratome blade, although other sources are possible. The interface debris and inflammation can be reduced or eliminated by cleaning the microkeratome blade before use.

In vivo confocal imaging of corneal neovascularization.

PURPOSE: To investigate the cellular dynamics of vessel formation during corneal neovascularization in the living eye by confocal microscopy. METHODS: Corneal neovascularization was initiated by placing a 7-0 silk suture through the corneal stroma 3 mm from the limbus at the 12 o'clock position in both eyes of 10 New Zealand white rabbits. The corneas were examined for vessel ingrowth at intervals from 1 to 15 days after suture placement using a tandem scanning confocal microscope with a 20X water immersion objective, as well as a slit-lamp biomicroscope. Changes in the limbal vessels were recorded on videotape for later analysis. As early vessel growth appeared to be associated with corneal nerves, the total number of sprouts and the number of sprouts along nerves were counted in confocal images, and the results analyzed for statistical significance. Vessel growth and the structural relationship between vascular buds and the deep stromal nerves were examined by light and transmission electron microscopy. RESULTS: The early events of cell migration from the limbal microvessels were found to be associated with the deep stromal nerves; although this association was easily visualized by confocal microscopy, it could not be documented by slit-lamp biomicroscopy. By 18 h after suture placement, the limbal vessels were dilated and the first vascular buds appeared as short, pointed, or flat-topped protrusions from the deep limbal capillaries. By 96 h, the capillary buds had increased in density and had begun to form lumens. Movement of red blood cells was established between 72 and 80 h after the first signs of bud formation, at the same time that cells of immune origin were seen. Confocal microscopy revealed and transmission electron microscopy verified that new bud formation began with the formation of vascular tubes by endothelial migration along the deep stromal nerves. The total number of sprouts and the number of sprouts associated with stromal nerves were similar on days 1 and 2 but differed on days 3-7, suggesting an association between sprouts and nerves in the early stages of neovascularization. CONCLUSION: Using real-time white light confocal microscopy, we were able, for the first time, to observe the process of corneal neovascularization in the living eye, from the earliest stages within hours after initiation to 2 weeks. The deep stromal nerves appear to serve as a focus for the growth of new vessels, by attracting and supporting vessel growth and/or by providing a potential space for movement of the endothelial cells. Confocal microscopy may provide a new approach to achieving a better understanding of the mechanisms involved in corneal neovascularization.

Characterization of fibrous retrocorneal membrane by confocal microscopy.

PURPOSE: To study the appearance of a fibrous retrocorneal membrane as seen by confocal microscopy. METHODS: A 67-year-old white woman with a history of multiple ocular surgeries, including repeated penetrating keratoplasties for aphakic bullous keratopathy, developed a retrocorneal membrane in the right eye. The membrane was first noticed 3 years after the last corneal transplant and remained stable subsequently. The patient was examined by in vivo white light tandem-scanning confocal microscopy. RESULTS: At the level of the retrocorneal membrane, confocal microscopy disclosed the presence of a hyperreflective fibrous-appearing layer. Normal endothelial cells could not be found. Anterior to the hyperreflective layer, activated keratocytes were identified. CONCLUSION: Confocal microscopy may allow noninvasive diagnosis of fibrous retrocorneal membrane. Additionally, our data suggest that the posterior keratocytes might play a role in the production and deposition of fibrous tissue.

Is there any evidence for a post-tubal sterilization syndrome?

OBJECTIVE: To review the literature on menstrual and hormonal changes in women who under go tubal sterilization. DESIGN: A systematic review through MEDLINE and a literature search identified more than 200 articles in the English literature from which the most relevant were selected for this review. RESULT(S): Many authors have investigated the sequelae of female sterilization. Increased premenstrual distress, heavier and more prolonged menstrual bleeding, and increased dysmenorrhea have been reported. However, failure to control for age, parity, obesity, previous contraceptive use, interval since sterilization, or type of sterilization may have affected study results. Most studies that have controlled for these important variables have not reported significant changes, except in women who undergo sterilization between 20 and 29 years of age. CONCLUSION(S): Tubal sterilization is not associated with an increased risk of menstrual dysfunction, dysmenorrhea, or increased premenstrual distress in women who undergo the procedure after age 30 years. There may be some increased risk for younger women, although they do not appear to undergo significant hormonal changes.

PIP: Evidence for a post-tubal sterilization syndrome was sought in a literature review of over 200 English-language articles. This syndrome has been described, variously, as encompassing symptoms such as abnormal bleeding and/or pain, changes in sexual behavior and emotional health, exacerbation of premenstrual symptoms, and menstrual symptoms necessitating hysterectomy or tubal reanastomosis. It has been postulated that the destruction of the fallopian tube and, in some cases, portions of the mesosalpinx, alters the blood supply to the ovary, with consequent impairment of follicular growth and corpus luteum function. Evaluation of the research literature is hindered by the failure to control for age, parity, obesity, previous contraceptive use, interval since sterilization, or type of sterilization. Despite the vast discrepancies in the research findings, it does appear that women 20-29 years of age with pre-existing histories of menstrual dysfunction are at increased risk of some post-tubal sterilization symptoms. After this age, however, there is no consistent evidence that tubal sterilization is associated with an increased risk of menstrual dysfunction, dysmenorrhea, or increased premenstrual distress.

Does creatinine adjustment of urinary pregnanediol glucuronide reduce or introduce measurement error?

Correlation between urinary pregnanediol and serum progesterone measurements and the influence of age, race, smoking and urinary creatinine adjustment was determined during the luteal phase of the menstrual cycle in 175 volunteers. A decline in serum progesterone was observed with increasing age. Mean baseline urinary creatinine declined with increasing age in non-smokers and was not affected by race or baseline weight. An excellent correlation between urinary pregnanediol glucuronide and serum progesterone levels existed except when urinary pregnanediol concentrations were adjusted using creatinine measurements in older individuals. Adjustment of urinary pregnanediol glucuronide concentration using creatinine measurement is therefore discouraged.

Corneal thickness measurements with the Orbscan Topography System and ultrasonic pachymetry.

PURPOSE: To compare corneal thickness measurements obtained with a new instrument, the Orbscan Topography System, with those obtained with the DGH ultrasonic pachymeter and to assess the agreement and repeatability of the two devices. SETTING: LSU Eye Center, New Orleans, Louisiana, USA. METHODS: Measurement agreement was assessed in 51 eyes of 26 normal volunteers using both Orbscan and ultrasonic pachymetry. Repeatability for the instruments was measured in 10 eyes of 5 additional volunteers. Corneal thicknesses were compared using the analysis of variance (ANOVA). The relationship between the devices was assessed by analysis of regression (ANOR). RESULTS: In the measurement agreement experiment, the mean corneal thickness was 571.3 microm +/- 6.21 SEM with the Orbscan system and 543.3 +/- 7.49 microm with ultrasonic pachymetry; these values were significantly different (F test, ANOVA, P = .0048). In the repeatability experiment, the mean thickness was 561.1 +/- 8.42 microm with the Orbscan system and 537.4 +/- 5.84 microm with ultrasound pachymetry; these values were also significantly different (F test, ANOVA, P = .0003). Analysis of regression showed a significant linear regression between the values obtained with the devices (P = .0001, F test, ANOR). CONCLUSIONS: In both studies, the Orbscan system obtained statistically significantly different and higher values for corneal thickness. Regression analysis suggests that over the range of values in this study, the two devices differ by a constant amount (intercept and slope). The nonzero intercept of this regression shows that the values from the devices differ and cannot be directly substituted for each other. We therefore conclude that in this study, Orbscan system measurements of corneal thickness were 23 to 28 microm greater than ultrasonic pachymeter measurements. Linear regression equations may be developed for the results of measurements from the two devices and used as a precise transformation factor for the values obtained with the two devices.

Surgical repair of a traumatic iridodialysis.

A novel method for the surgical repair of traumatic iridodialysis is described. This method involves the use of a double-armed suture with straight needles to re-appose the iris by means of mattress sutures. In the case report presented, good cosmetic and optical results were obtained.

Diagnosis of bacterial contact lens related keratitis with the white-light confocal microscope.

PURPOSE: We used white-light confocal microscopy to identify the causative organisms in two patients with contact lens related keratitis. METHODS: The corneal infiltrates were examined by confocal microscopy and corneal specimens were obtained for culture. RESULTS: In both patients, confocal microscopy revealed 1.5- to 2-micron diameter hyper-reflective bodies below the level of the epithelium. The sizes of these structures were consistent with those of bacteria. The corneal cultures from one patient grew Staphylococcus werneri and the cultures from the other patient grew Streptococcus viridans. CONCLUSIONS: The confocal microscope permitted the in vivo observation of what we believe to be bacteria in patients diagnosed with contact lens related keratitis.

Transient corneal stromal and endothelial changes following soft contact lens wear: a study with confocal microscopy.

PURPOSE: Previous studies have described transient corneal endothelial changes in non-contact lens wearers after a short period of soft contact lens wear by means of contact and noncontact specular microscopy and modified slit lamp biomicroscopy, which provide magnifications from 60 to 100x. In this investigation, we documented and characterized these contact lens-related corneal changes using the white light, real-time confocal microscope, which is capable of cellular resolution imaging of all layers within the cornea at magnifications of 100 to 500x. METHODS: We used a clinical confocal microscope to study corneal changes in three patients wearing a high water content soft contact lens for the first time. RESULTS: In one patient, endothelial changes consisting of irregularly shaped, round or oval, dark regions were observed within the endothelial mosaic. Scattered hyper-reflective keratocyte nuclei were seen in the posterior stroma. The keratocytic and endothelial changes were most evident 20 minutes after placement of the lens. By 30 minutes, the changes were fewer and less prominent, and the brightness of the highly reflective keratocyte nuclei had decreased. CONCLUSIONS: These studies show, for the first time, that the transient changes associated with contact lens wear occur not only in the endothelium, but also in the corneal stroma. It has been suggested that the changes result from an increase in CO2 and lactic acid, which causes a transient reduction in the corneal pH. We hypothesize that the resulting acidic environment may induce gene expression that causes changes in the involved nuclei, which in the keratocytes become hyper-reflective, and in the endothelium become enlarged, resulting in posterior displacement of the cell membrane and producing the dark "blebs" and irregular lines observed at this level of the posterior cornea.

Confocal microscopy of corneal graft rejection.

Corneal allografts were transplanted into inflamed and vascularized graft beds in rabbit eyes. The grafts were examined every 4 days by slit-lamp biomicroscopy and scanning confocal microscopy. Confocal images were recorded with a video camera and computer enhanced in real-time. Layers of the cornea were visualized in serial optical sections parallel to the epithelium. In the third postoperative week, signs of graft rejection were observed; slit-lamp examination revealed a circumferential line of epithelial rejection, along with cloudiness and edema. Vessels were observed growing into the graft. By confocal microscopy, infiltrating cells were seen in the graft stroma. Foci of cells were especially pronounced around the sutures. Scattered leukocyte infiltrates were prominent at capillary terminals. There was an accompanying reduction in the stromal keratocyte density in the region of the infiltrate. Additionally, various degrees of fibrosis were noted around each suture and at the host-graft interface. Confocal microscopy may provide a valuable clinical tool for determining the earliest indicators of an antigraft immune response, and as an aid in the differential diagnosis of other inflammatory conditions of the cornea.