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Resume But Etudier l’effet de l’inflammation oculaire au cours des uveites actives sur l’endothelium corneen. Patients et methodes Etude prospective comparative portant sur 63 yeux de 38 patients presentant une uveite active avec un groupe controle de 84 yeux de 42 temoins. Les deux groupes ont eu un examen ophtalmologique complet, une mesure au laser flare photometer et une microscopie speculaire. Pour le groupe d’uveite active, un examen de controle, une mesure au laser flare photometer et une microscopie speculaire etaient faits 1 mois apres l’initiation du traitement. Resultats L’âge moyen des patients avec une uveite active etait de 33 ans (extremes : 9-67 ans) avec 21 hommes et 17 femmes. Pour le groupe d’uveite active, la valeur moyenne du flare a l’inclusion etait de 32 ph/ms (extremes : 15-100 ph/ms) avec un flare≥ 50 dans 13 yeux (21 %) et Conclusions En cas d’uveite active, la microscopie speculaire permet de mettre en evidence des anomalies qualitatives transitoires de l’endothelium corneen, qui dependent de la severite de l’inflammation de la chambre anterieure telle que mesuree par le laser flare meter.

Purpose To assess agreement between 3 measures of central corneal thickness (CCT) taken over a few minutes from nominally normal eyes with a non-contact specular microscope. Methods 100 eyes from 100 healthy adults (with an average age of 22 y) were assessed using the Topcon 3000 P instrument to obtain a high quality image of the endothelium and pachymetry. Results The group mean CCT values from the 1st, 2nd and 3rd measures were 0.519, 0.520 and 0.520 mm, but the sets of values could differ by between – 0.020 mm and + 0.029 mm, i.e. between - 4.0 and + 5.6% of the average values. Paired comparisons (e.g. 2nd vs. 1st set) indicated limits of agreement (LoA) to be between - 0.020 and + 0.020 mm of the averaged value. Across the 3 measures, the averaged SD was 0.005 mm to give an estimate of the intra-subject variability (as the coefficient of variation, COV) of 0.91% (range 0 to 2.3%). The variability in the pachymetry measures was not predictably related to the averaged values of CCT (r = 0.022) or self-reported refractive error of the subjects (r = 0.012). Some repeat pachymetry assessments obviously included the same region of the endothelium. Conclusions Single pachymetry measures with a non-contact specular microscope are only likely to be able to generate CCT estimates within +/− 4% of the expected average values. This repeatability is comparable to single image estimates of endothelial cell density and therefore acceptable in most cases.

Background The purpose of this review was to evaluate the consistency of central corneal thickness (CCT) values reported with use of Topcon SP-2000 P and SP-3000 P non-contact specular microscopes since their introduction in 1999 with the two microscopes having been commonly used in a wide range of studies. Methods As a primary resource, PubMed was used to search for peer-reviewed articles in any language that included CCT values obtained with non-contact specular microscopy reported for humans with nominally healthy corneas. Relevant articles were obtained and any cited publications also checked. Results A total of 76 articles were identified which reported CCT on different small-to-moderate sized groups of individuals, published between 1999 and 2019. From these, an overall group mean CCT value of 0.525 ± 0.013 mm (median 0.525 mm) can be calculated. An estimated 95 % confidence interval (CI, based on 1.96 SD) would be between 0.500 and 0.550 mm. For the two Topcon models, the group mean ± SD values were 0.529 ± 0.013 mm and 0.517 ± 010 mm respectively. An assessment of the CCT data sets in relation to the reported average age indicated no statistically significant effect (p = 0.289, r = −0.129). Very similar average CCT values were also encountered in 4 other reports where these microscopes were used in large-scale population studies as well as in 2 other reports using the newer Topcon SP-1 P model. Conclusions The Topcon stand-alone non-contact specular microscopes have yielded consistent and predictable corneal thickness measures over many years.

Purpose To assess the impact of using different numbers of cells in calculations of the coefficient of variation (COV) value for normal and polymegethous endothelia Methods Four sets of 20 non-contact specular microscope images obtained from Caucasian individuals were assessed, and categorized according to the extent of polymegethism, i.e. grade 0 (none), grade 1 (mild), grade 2 (moderate) and grade 3 (substantial). Cell areas were measured manually and then values for between 2 and 100 cells were progressively added and averaged to generate COV estimates. These were then assessed in terms of their relative values (as percentages +/- SD) in relation to the value obtained on over 100 cells. Results For the 4 sets of endothelia with group-mean COV values of 25.8, 33.1, 45.1 and 56.8%, the reliability of the COV estimates realized asymptotic values of close to ±1.0, ±2.7, ±3.6 and ±5.0% with 90 cells, but with greater uncertainty with few numbers of cells, e.g. only to within ±3.4, ±5.3, ±6.1 and ±7.9% with 75 cells. Conclusions COV estimates for the corneal endothelium are dependent on the number of cells used in the calculations. It is recommended that every effort should be made to not only assess 75–100 cells per endothelial image, but that this number should be the same or very similar for all endothelial images in a particular data set so that the uncertainly (or estimated proportional error) in the estimates is balanced.

The corneal endothelium state is verified on the basis of an in vivo specular microscope image from which the shape and density of cells are exploited for data description. Due to the relatively low image quality resulting from a high magnification of the living, non-stained tissue, both manual and automatic analysis of the data is a challenging task. Although, many automatic or semi-automatic solutions have already been introduced, all of them are prone to inaccuracy. This work presents a comparison of four methods (fully-automated or semi-automated) for endothelial cell segmentation, all of which represent a different approach to cell segmentation; fast robust stochastic watershed (FRSW), KH method, active contours solution (SNAKE), and TOPCON ImageNET. Moreover, an improvement framework is introduced which aims to unify precise cell border location in images pre-processed with differing techniques. Finally, the influence of the selected methods on clinical parameters is examined, both with and without the improvement framework application. The experiments revealed that although the image segmentation approaches differ, the measures calculated for clinical parameters are in high accordance when CV (coefficient of variation), and CVSL (coefficient of variation of cell sides length) are considered. Higher variation was noticed for the H (hexagonality) metric. Utilisation of the improvement framework assured better repeatability of precise endothelial cell border location between the methods while diminishing the dispersion of clinical parameter values calculated for such images. Finally, it was proven statistically that the image processing method applied for endothelial cell analysis does not influence the ability to differentiate between the images using medical parameters.

Purpose To analyze corneal surface temperature profile in a young and healthy study population and to determine the impact of corneal thickness (CT), anterior chamber depth (ACD), and endothelial cell density (ECD) on surface temperature. Methods In this prospective, single-center study 61 healthy right eyes of 61 subjects without tear film pathologies (mean age 24.9 ± 6.7 years) were recruited. Ocular surface temperature (OST) was measured with the Ocular Surface Thermographer TG-1000. From Pentacam HR CT and ACD, and from specular microscopy ECD and central corneal thickness (CCT) were acquired. From the raw measurement data (OST, CT and ACD) we extracted a) local OST the corneal center and 3 mm away from the center at the 3, 6, and 9 o‘clock positions, and b) Zernike parameters Z1, Z2 and Z3 to evaluate the general temperature profile within a 6 mm circular area around the center. Results Overall, there was no correlation between OST and CT, ACD or ECD. Local OST did not correlate with CT at any measurement position. On average local OST was highest at measurement positions where CT was lowest, but without reaching statistical significance. Baseline OST was highest at thin corneal regions and temperature decay over time was smallest in those regions. Z1, Z2 and Z3 correlated well with CT. Conclusions In healthy subjects corneal thickness, endothelial cell density and anterior chamber depth have no effect on corneal surface temperature. The general temperature profile seems to be influenced by the corneal thickness profile effecting a higher temperature and lower decay at thinner corneal regions.

Optisol–GS storage medium allows donor corneas to remain viable until they are transplanted to cornea-blind recipients. In order to remain viable, the corneal endothelial cell density (ECD) must remain above 2 200 cells per mm2. The objective of this study is to determine how long donor corneas may remain viable in Optisol-GS based on their ECD. Although our findings show that the ECD of corneas stored in Optisol-GS decreased steadily, it remained above the critical level of 2 200 cells per mm2 for up to 9 days, suggesting that corneal buttons may remain viable for at least this amount of time.

Purpose To assess the variation in central corneal thickness (CCT) following the instillation of oxybuprocaine hydrochloride (0.4%), in normal subjects. Methods This was a randomized, prospective study of CCT measurements (before and after the instillation of topical anaesthesia) obtained with the Topcon SP-3000P noncontact specular microscope, in 60 eyes of thirty subjects. The subjects’ mean age was 20 ± 1 years (mean ± SD). In each subject, one eye was treated with one drop of oxybuprocaine hydrochloride (HCl) and the fellow eye with one drop of normal saline (control). The SP-3000P CCT readings were first obtained before instillation (baseline) and monitored every 30 s after instillation of each eye drop for a period of 10 min. Results The mean baseline CCT for oxybuprocaine was 526 ± 23 μm. Ten minutes after, it was 526 ± 24 μm. In the control, the mean CCT was 526 ± 27 μm, 10 min after it was 526 ± 28 μm. The mean variation in CCT measurement was −0.7 ± 3.1 (5.5 to −6.8 μm, 95% CI) for oxybuprocaine and −0.6 ± 4.1 μm (7.5 and −8.6 μm, 95% CI) for the fellow eyes (P > 0.05). There was no significant variation among the 20 CCT columns for either oxybuprocaine or the control group (P > 0.05 for both). Conclusions One drop of topical oxybuprocaine 0.4% did not cause a significant change in CCT at up to 10 min following instillation. However, higher differences were observed at 2.30 min and 4.30 min after instillation.

Objetivo: Evaluar el efecto de la inyección intravítrea de 0,5mg ranibizumab sobre el endotelio corneal en pacientes con degeneración macular asociada a la edad (DMAE). Método: Estudio piloto de serie de casos, observacional y prospectivo con observador enmascarado. Veintiséis ojos (26 pacientes) con DMAE fueron evaluados. Todos los pacientes recibieron 1 inyección intravítrea mensual de 0,5mg de ranibizumab durante 3 meses consecutivos. El periodo de seguimiento fue de 6 meses. El endotelio corneal central fue evaluado antes, a los 7 días y a los 6 meses de la primera inyección de ranibizumab con microscopía especular. La densidad de las células endoteliales, coeficiente de variación del tamaño celular y porcentaje de hexagonalidad celular fueron analizados. También fue medido el espesor corneal central. Resultados: No se encontraron diferencias estadísticamente significativas entre los valores preinyección y postinyección a los 7 días y 6 meses de la primera inyección de ranibizumab en las densidades de células endoteliales, coeficientes de variación del tamaño celular y porcentajes de hexagonalidad celular (p>0,5). Tampoco se encontraron modificaciones significativas en el espesor corneal central a lo largo del periodo de seguimiento (p>0,5). Conclusiones: Inyecciones intravítreas repetidas de 0,5mg ranibizumab no parecen causar cambios importantes sobre el endotelio corneal a los 6 meses de seguimiento. Purpose: To determine the effect of intravitreal injection of 0.5mg ranibizumab on the corneal endothelium in patients with age-related macular degeneration (AMD). Methods: Observational, prospective case series pilot study. Twenty-six eyes of 26 consecutive patients with AMD were evaluated. All participants received one monthly intravitreal injections of 0.5mg ranibizumab for three consecutive months. The follow-up period was 6 months. Central corneal specular microscopy was performed before injection and at 7 days and 6 months after the first intravitreal injection. The endothelial cell density, coefficient of variation of cell size, and percentage of hexagonal cells were analyzed and the central corneal thickness was measured. Results: There were no significant differences in the endothelial cell densities, coefficients of variation of cell size and percentages of hexagonal cells before injection and at 7 days and 6 months after the first intravitreal ranibizumab injection (P >0.5). There was also no significant difference in central corneal thickness measurements through the follow-up period (P >0.5). Conclusions: Repeated intravitreal injections of 0.5mg ranibizumab do not seem to cause substantial changes in the corneal endothelium.

Specular microscopy is widely used to study the human corneal endothelium status in vivo. In this paper, the corneal endothelium is represented as a binary image composed of the cell inscribed circles. The granulometric distribution function of the complement of this image is used as a functional descriptor, which provides information about the shape, size and spatial arrangement of cells. Experimental evaluation using bootstrap techniques shows its ability to discriminate between controls and pathological cases. It represents a reliable and graphical alternative to the classical indices (cell density, hexagonality and coefficient of variation of cell areas), which behave poorly when detecting subtle abnormalities.

Purpose To determine the usefulness of the Pentacam corneal volume assay in the assessment of corneal endothelial damage caused by phacoemulsification and aspiration (PEA). Design Prospective, comparative, observational case series. Methods PEA was performed in 85 eyes by three surgeons under different conditions. Central cell density (CD) was determined using a specular microscope before and one month after surgery. Pentacam was used before and one day, one week, and one month after surgery to determine 3- and 10-mm corneal volumes. Results For all surgeons, no significant differences in the 3-mm corneal volumes were noted between the before and one-month after surgery values. However, 10-mm corneal volumes at one month were significantly higher than preoperative levels. No correlation was noted between the increasing rate of the 10-mm corneal volume and decreasing rate of CD. Conclusions Pentacam-determined corneal volumes may be useful in assessing PEA-caused corneal damage.

PURPOSE Sustained increase in intraocular pressure (IOP) in humans results in a loss of corneal endothelial cells and an increase of corneal thickness. The effects of chronically elevated IOP on the corneal endothelium of monkeys with laser-induced ocular hypertension, a commonly used animal model of human glaucoma have not been documented. This study examined the central corneal thickness (CCT), the corneal endothelial cell density (ECD), and the corneal endothelial cell size (ACS) in Rhesus monkeys with experimental ocular hypertension. Materials and methods. Ten male monkeys with argon laser-induced ocular hypertension in one eye for an average duration of 2.4+/-0.7 years, were sedated with ketamine hydrochloride, and the CCT, ECD, and ACS measured at the center of the cornea of both eyes with a Topcon SP-2000P non-contact specular microscope (Topcon America Corporation((R)), Paramus, NJ, USA). CCT was also measured using a DHG-500 Pachette ultrasonic pachymeter (DHG Technology Inc., Exton, PA, USA). Mean and standard deviation (S.D.) of CCT, ECD and ACS for each eye was calculated and statistically compared.Results. Mean CCT in the hypertensive and normal eyes measured by specular microscopy was 0.477+/-0.023mm and 0.468+/-0.020 mm, respectively. Mean ECD in the hypertensive and normal eyes was 2601.7+/-631.8 and 3990.2+/-402.9 cells mm(-2), respectively. The mean size of the endothelial cells was 252.4+/-23.9 micro m(2) in the normal eye and 408.7+/-115.0 microm m(2) in the hypertensive eye. No significant difference in the measurement of CCT was observed between the specular microscope and the pachymeter (p=0.46). No significant difference in the mean CCT was observed between the two eyes (p=0.4820), whereas the mean ECD was significantly lower in the hypertensive eye than in the normal eye (p

This paper presents an application to a medical problem of methods of shape analysis based on mathematical morphology. The medical problem consists on the detection of abnormalities in the corneal endothelium, a tissue composed by quasi-planar cells of ideally regular hexagonal shape. Images of this tissue are taken by a specular microscope and used to evaluate the corneal endothelium status. Up to now, cell density, hexagonality and an analysis of cell areas are the usual descriptors of a corneal endothelium. These parameters are not sensitive enough to detect subtle lesions. What this paper proposes is an analysis based on granulometries, which are size-shape descriptors widely used in Mathematical Morphology. Applications of granulometries lead to distribution functions whose moments are used as shape descriptors. Former approaches proposed a global evaluation of the whole corneal endothelium but irregularities affecting to a few cells could be ignored. Differently to that approach, this paper uses the granulometric size distribution of each cell. A group of normal cells is chosen as controls and a given cell is classified as normal or abnormal by comparing its granulometric size distribution with the corresponding distributions of the controls. The technique is illustrated with the analysis of some images of corneal endothelia.

Images of corneal endothelium obtained from specular microscopy are of great importance in the evaluation of the corneal endothelium status. Several commercial tools provide some numerical descriptors to characterize these images in terms of cell density, hexagonality, and some descriptive statistics of the cell areas. However, it is a too simple analysis that only detects severe abnormal endothelia with many irregular and large cells. Detection of subtle abnormalities needs a more refined analysis. This paper proposes a shape-size descriptor based on some modified versions of the geometric covariogram. This descriptor is presented as a valid alternative to the classical analysis that provides a reliable, visual, and easy evaluation of the corneal endothelium. Control images of normal endothelia can be used to classify a given image as normal or abnormal with respect to these controls by means of a graphical test.

Specular microscopy is a common practice in Ophthalmology. The corneal endothelium status is usually evaluated by means of the density, the hexagonality, the mean, the standard deviation and the coefficient of variation of cell areas. We propose to replace the cell area moments by the corresponding moments of a different probability distribution, the granulometric size distribution associated to a disc. All cells touching the frame are ignored by the area moments but used by the granulometric moments. Twenty images have been analyzed. When the size of the focused region is reduced, the area moments show a greater variation than the corresponding granulometric moments.

OBJECTIVE: Quantitative assessments of in vivo endothelial cell density, size and shape after cataract surgery provide an important tool for control of surgical quality. To investigate reproducibility, quality and advantages or disadvantages of individual specular micrographs obtained with a non-contact microscope, endothelial cell parameters were compared with micrographs obtained with a contact specular microscope. STUDY DESIGN: Five photographs of the central cornea of 24 eyes (17 patients) 6 months after clear-corneal cataract surgery were assessed by non-contact, using the zoom mode, and contact specular microscopy, respectively. After qualitative morphological and quantitative morphometric analysis of the 240 photographs, data of both methods were compared. SETTING: Department of Ophthalmology, Giessen, Germany. MAIN OUTCOME: Image analysis of different cell parameters showed a few significant differences in both methods: Intraphotographic analysis showed no significant coefficient variation of mean cell parameters, while interphotographic analysis detected a significantly higher spread of many values, such as cell density and area in non-contact specular microscopy. The rate of obtaining endothelial images was very successful. CONCLUSIONS: The clinical advantages of the non-contact instrument are the high successful rate of taking images with safety and useful reproducibility. The smaller field obtained with the noncontact system allows estimation of endothelial morphological and quantitative parameters. More detailed information and precision of the posterior endothelial surface was provided by the contact specular microscope.

Objective: The use of specular microscopy to photograph in-vivo intraocular lens defects produced as a result of Nd-YAG laser posterior capsulotomy. Patients: Thirty randomly selected patients following Nd-YAG laser posterior capsulotomy. IOL: Lathe cut PMMA planoconvex. Results: IOL damage was found in 28 (93%) of IOLs. The most common damage was a crater with melted margins, craters with irregular margins and inclusions are also seen. Stellate defects in the intraocular lens were found in two cases. Conclusion: Specular microscopy performed during and after Nd-YAG laser capsulotomy demonstrates various kinds of intraocular lens defect.

Our purpose was to learn whether specular microscopy is useful in evaluating corneal epithelia with peripheral corneal desiccation (3 and 9 o'clock staining), which affects most rigid gas permeable contact lens wearers. The Keeler-Koran specular microscope was used to photograph corneas of 10 lens wearers and 10 control subjects. Photoanalysis revealed that lens wearers had reduced peripheral and increased central cell areas compared to control subjects, and corneal staining was correlated with decreased cell areas. Specular microscopy was found to be valuable for analyzing and quantifying the epithelium.

In an examination of more than 200 randomly selected young and old people, complaints were made in a number of cases about symptoms of dry eyes. An examination of the left eye in each case using a specular microscope revealed a characteristic appearance of the lipid layer of the precorneal tear film with dry eyes. The lipid layer looked jagged, like broken ice, or cloudy, spotty, or stripped. It had a gray color. The interference patterns were documented with photographs. In addition to the Schirmer test and the breakup time test, specular microscopy is a simple and fast process for the recognition of dry eye.

espanolObjetivo/Metodo: Mujer hipermetrope de 50 anos desea informacion sobre cirugia refractiva. En la cornea se aprecia vesiculas y bandas en la membrana de Descement y endotelio catalogandose de distrofia polimorfa posterior (DPP). El recuento endotelial resulta bajo por lo que se le contraindica cualquier cirugia refractiva corneal. Resultados/Conclusiones: La presencia de vesiculas y bandas a nivel de la membrana de Descement y endotelio es caracteristico de una DPP. En estos casos resulta obligatorio realizar una microscopia especular previa a una cirugia refractiva con laser excimer. Un recuento de celulas endoteliales bajo puede constituir una contraindicacion para el LASIK hipermetropico en casos de DDP por el posible riesgo de descompensacion endotelial. EnglishObjective/Method: A 50-year-old hyperopic woman requested information about refractive surgery. Vesicle and band lesions at Descemet’s membrane and endothelium were suggestive of posterior polymorphous dystrophy (PPD). Lower than normal endothelial cell densities were detected. A corneal refractive procedure was not recommended in this case. Results/Conclusions: The presence of vesicles and bands at Descemet’s membrane and endothelium is suggestive of PPD. Specular microscopy is mandatory in such patients, although corneal decompensation is not evident. A low endothelial cell count may be a contraindication for a hyperopic LASIK procedure in cases of PPD because of the possible risk of corneal decompensation.

Specular microscopy was used for investigation of cellular reactions on the intraocular lens (10L) anterior surface of Heparin surface-modified (HSM) versus regular polymethyl methacrylate (PMMA) lenses (Pharmacia types 7000 versus 700B, respectively). The double-masked randomized study included 53 patients investigated at 1 and 4 weeks postoperatively. Giant cells were only found on control lenses and more frequently at 4 weeks. Small cells were found on both lens types, but in a higher frequency on the control lenses. The number of small cells decreased during the first 4 weeks on both the control and HSM lenses. However, those control lenses that had giant cells on their surface showed an increase in the number of small cells during the same time. The results of the current study show that HSM lenses give rise to less postoperative inflammatory cellular reactions than regular PMMA lenses.

Purpose To report the endothelial cell loss and clinical outcomes in Descemet stripping automated endothelial keratoplasty (DSAEK) with internationally shipped, precut donor corneas. Design Retrospective analysis of a noncomparative case series. Methods The setting was a single hospital. The clinical results of 134 eyes of 128 patients who underwent DSAEK in Kyoto, Japan, with internationally shipped precut donor corneas from Portland, Oregon, or Seattle, Washington, were evaluated. In addition, 40 precut donor corneas from Seattle were evaluated in respect to the postprecut international shipment-related loss of corneal endothelial cell density (ECD). Observation procedures were noncontact specular microscopy. The main outcome measures were the evaluation of international shipment-related ECD loss, postoperative ECD, visual recovery, and complications. Results The mean postprecut ECD loss in 40 donor corneas during international shipment was 2.3%. The mean elapsed time from cut to surgery was 63.2 ± 31.1 hours. At 6, 12, 24, and 36 months postoperatively, the mean ECD of the internationally shipped donor corneas was 2038, 1933, 1670, and 1431 cells/mm 2 , respectively. The mean ECD loss at 6, 12, 24, 36 months after DSAEK was 30%, 34%, 44%, and 51%, respectively. Preoperative logarithm of the minimum angle of resolution (logMAR) best spectacle-corrected visual acuity was 1.40 ± 0.55, and at 12 months after DSAEK was 0.22 ± 0.19. Complications included graft dislocation in 12 eyes (8.9%) and graft rejection in 3 eyes (2.2%). Conclusions The present study shows that the outcomes of DSAEK with internationally shipped precut donor corneas were acceptable and that the additional endothelial cell loss associated with international shipment was minimal and did not affect the clinical results.

To observe longitudinal changes in the corneal endothelium after pediatric cataract surgery with intraocular lens implantation.Prospective, longitudinal study.settings: Iladevi Cataract and IOL Research Centre, Ahmedabad, India. study population: This study included 100 pediatric eyes undergoing cataract surgery with intraocular lens implantation. Posterior capsule management was based on the status of the posterior capsule. Two-port anterior limbal vitrectomy was carried out after posterior capsule plaque peeling. observation procedures: Corneal endothelial morphologic features: endothelial cell density (cell/mm(2)), coefficient of variation, percentage of hexagonality, and central corneal thickness were assessed. main outcome measures: To evaluate whether there is a difference in endothelial cell morphologic features before surgery and 3 months after surgery and also whether pediatric cataract surgery with and without anterior vitrectomy has any impact on the endothelial cell morphologic features.A comparison of preoperative and postoperative specular microscopy is given here: endothelial cell density, 3225.1 ± 346.8 cells/mm(2) versus 3057.7 ± 330.1 cells/mm(2) (P.001); coefficient of variation, 27.5 ± 10.6 versus 37.7 ± 16.3 (P.001); percentage of hexagonality, 58.1 ± 15.3 versus 48.6 ± 13.4 (P.001); and central corneal thickness, 529 ± 30 μm versus 527 ± 34 μm (P = .64). There was 5.1% decrease in mean endothelial cell loss at 3 months after surgery. No statistically significant difference was noted in the percentage decrease in mean endothelial cell density between eyes undergoing cataract surgery with intact posterior capsules, eyes undergoing manual posterior capsulorrhexis without anterior limbal vitrectomy, and eyes undergoing anterior limbal vitrectomy (P = .543).Endothelial cell loss with currently practiced techniques of pediatric cataract surgery is within acceptable limits by adhering to the principles of close chamber technique.

A proper understanding of the endothelial cell morphology of the cornea is of great significance to the corneal surgeon. Specular microscopy allows direct visualization of endothelial cell morphology and a proper analysis of these data needs automated computerized type of systems. Automated pattern analysis seems to offer a good option in this direction. From our experience it appears that such systems can be used with great advantage in the analysis of endothelial cell morphology. The data obtained from such analysis help to develop some indices for various facets of endothelial cell morphology.

We studied the characteristics of the corneal epithelium by specular microscopy in 12 eyes of 11 patients, at three, six, and 16 months after epikeratophakia surgery. We found attenuation of cells; irregular shape; decreased density; loss of differentiation into dark and light cells and into small, medium, and large cells; and poor interdigitation between adjacent cells. Corneal hypesthesia noted in these grafts may contribute to the aberrant epithelial characteristics.

Extended-wear contact lenses (EWCL) are being used increasingly for the correction of aphakia in infants, but there is a lack of data documenting their effects on the corneas of young children. Therefore, corneal studies were performed on infant monkeys wearing EWCL for the correction of surgical aphakia. Nine newborn monkeys underwent unilateral lensectomy and anterior vitrectomy. Seven eyes were fitted with aphakic EWCL postoperatively and two wore no lenses. After at least six months, corneas were studied with slit-lamp and specular microscopy, and with light microscopy (LM) and electron microscopy (EM). Small central corneal opacities developed in two aphakic eyes corrected with EWCL after episodes of keratoconjunctivitis. One of these corneas was found to have a mildly increased coefficient of variation (CV) of endothelial cell size (polymegathism). Although EWCL are well tolerated by the corneas of aphakic infant primates, their association with endothelial polymegathism, which may indicate physiologic compromise, mandates careful long-term follow-up.

In 20 patients, corneal endothelium was examined by specular microscopy after acute angle-closure glaucoma, and before any surgical treatment in order to assess possible damage during pressure induced abnormal hydration of the cornea. The mean intraocular pressure was elevated to 55 mm Hg and had lasted, on an average, 47 (5--192) hours. The mean endothelial cell density in the affected eye was 1534 and in the nonaffected fellow eye 2243 cells/mm2 (mean decrease 33%, P = 0.002). The amount of cell loss correlates with the duration of the intraocular pressure increase. Thirty-five percent of these patients presented a bilateral cornea guttata. This high incidence of endothelial dystrophy was confirmed in a retrospective specular microscopic study in 20 patients with a history of unilateral acute angle-closure glaucoma. The decreased number of endothelial cells after acute angle-closure glaucoma frequently combined with bilateral cornea guttata, accounts for the corneal degeneration in these patients following a later cataract extraction.

A technique for the rapid measurement of cell size in the corneal endothelium is demonstrated. The technique involves the measurement of nearest-neighbor distances by centering a circular target within the cell boundaries. Measurements of mean cell area as a function of age were performed and compared with similar planimetric area measurements. The age independence of a dimensionless shape factor indicates that the average cell shape remains unchanged even though the endothelium becomes increasingly pleomorphic with age.

Clinical specular microscopic examination of 17 patients with features common to the iridocorneal endothelial syndrome (including Chandler's syndrome, iris nevus syndrome, and essential iris atrophy) showed pathognomonic endothelial changes and no areas of normal endothelial mosaic. Even in those patients with minimal anterior synechiae, gross central endothelial changes could be found, suggesting that the endothelial changes are primary and not secondary to the iris-corneal adhesions. Specular microscopy of the clinically uninvolved contralateral eye in these patients revealed frequent endothelial cell pleomorphism incommensurate with the patient's age. This study also confirmed the value of the specular microscope for qualitative endothelial observations.

Through the use of a scanning mirror system, the field of view has been expanded to as much as 0.9 mm in diameter. Both contact and non-contact specular microscopy are possible, each having advantages. In a research application, wound healing in rabbit endothelium is documented by time lapse photography. The study demonstrates the capability to return to an area of interest provided there is a landmark. Clinical applications and advantages over conventional specular microscopy are discussed.

Using specular microscopy and computer-assisted morphometry, we studied 27 eyes with pseudoexfoliation syndrome, 17 apparently normal fellow eyes, and 15 eyes of matched normal subjects with no ocular disease other than senile cataract. Endothelium of the eyes with pseudoexfoliation syndrome showed significantly lower cell density than did the endothelium from control eyes. Endothelium of both eyes of patients with unilateral pseudoexfoliation syndrome showed significant morphologic changes in cell size (polymegethism) and shape variability (pleomorphism); these changes were essentially the same in overtly affected and apparently normal fellow eyes. The results suggested that the corneal endothelial changes are consistent and might serve as an early sign of the disorder.

The interpretation of clinical specular microscopical images of abnormal corneal endothelium remains a problem in many instances when the relief mode is negative. This is primarily because different cellular changes occurring simultaneously present similar appearances. In this paper is compiled a number of specular images of small, dark (non-reflecting) cell changes in the endothelium which resemble one another and clinical examples, that have been induced in rabbit eyes by various means. Specific cells showing these changes have been relocated by scanning electron microscopy and orientated to match specular photomicrographs taken before fixation. This has allowed precise comparison of their specular and scanning electron microscopical appearances and the interpretation of the former by the latter. It is found that reversible changes are expressed as an excess of microvilli on the cells and minor inclination of the posterior cell membrane from the perpendicular with the axis of the microscope, and irreversible changes are due to cell fragmentation or total loss with exposure of Descemet's membrane to the aqueous humour. Re-examination of specular photomicrographs with this knowledge in mind indicates that very subtle differences in the specular images often betray the true nature of the cell change. An exception to the rule is included.

The toxicity and side effects of drugs and their adjuncts are reviewed according to effect on corneal epithelium, stroma, and endothelium, when topically applied to healthy or wounded surfaces, or introduced into the anterior chamber of the eye. Corneal research techniques are reviewed, including scanning and transmission electron microscopy, electrophysiological techniques, and specular microscope observation. Clinical interpretation of these results is discussed. Reviews of specific toxicologic techniques and of medications are cited. Present research makes it increasingly apparent that not only medications but also their preservatives cannot be considered innocuous. Preservatives may be effective yet less damaging to the ocular integument when used at lower concentrations than those presently available commercially. Complete avoidance of preservatives by the use of special dispensing systems is found increasingly desirable.

Samples from the center of a wide-field specular micrograph adequately assessed cell density and frequency distribution of cell areas. A preliminary analysis of the spread of values indicated whether an increased sample size was required. An algorithm determined how large a sample taken from the central photogreaph (three, five, or nine rectangles) was necessary to permit detection of a 10% change in cell area. This analysis of sample size also indicated that sampling by small-field specular microscopy was not representative of the surrounding square millimeter of corneal endothelium.

We examined and photographed the central corneal endothelium of 16 patients with the clinical specular microscope before and at intervals after cataract extraction. No detectable loss of the endothelial cells occurred in 75% of the patients, including 12 routine intracapsular cryoextractions and four phacoemulsifications of soft cataracts in young adults. Only one of the four cases of significant endothelial cell loss occurred in a normal cornea without demonstrable operative or postoperative complications. Two of the four corneas that lost central endothelial cells at cataract extraction continued to lose more cells during the ensuing weeks. A significant increase in central endothelial cell density was demonstrated in one patient. The four corneas with endothelial cell loss also had a significantly higher mean increase in corneal thickness postoperatively, although this was transient. All 16 corneas remained clear during the period of observation (maximum, 14 weeks), and long-term studies are needed to measure the chronic effects of the endothelial damage.

A patient with monocular retinoblastoma was examined with the wide-field specular microscope before undergoing enucleation. An unusual image on the corneal endothelium consisted of irregular oval dark structures within which bright reflections formed a lacy network. Light and electron microscopy confirmed these structures to be clusters of retinoblastoma cells adherent to the endothelium. These findings suggest that the specular microscope may aid in the diagnosis of intraocular tumors.

We evaluated the safety and efficacy of 2% methylcellulose as an adjunct for cataract extraction with implantation in cat and monkey models. When used intraoperatively, methylcellulose reduced the iridovitreal bulge during surgery. No significant increase in clinical inflammation occurred nor was there statistically significant intraocular pressure elevation at 24 hours, 7 days, or 90 days. In the cat model, the central corneal thickness increased at day seven in both control and methylcellulose eyes; this thickness persisted to 90 days. The endothelial cell loss decreased significantly at day 90 in methylcellulose eyes. In the monkey model, no statistically significant increase in corneal thickness occurred in control or methylcellulose eyes at day seven. The endothelial cell loss was greater than in the cat model in both control and methylcellulose eyes; there was no statistically significant difference between the two. Two percent methylcellulose was safe in both the cat and monkey models. It facilitated surgery in both models and reduced the endothelial cell loss in the cat eye. Key M70rds: cataract-implant surgery, methylcellulose, pachometry, specular microscopy, viscoelastic, viscosurgery

To understand the long-term effects of intraocular lens implantation on corneal endothelium, 52 eyes with intraocular lens implantations and 35 eyes with simple cataract extractions were studied using clinical specular microscopy. Endothelial photographs were obtained preoperatively and at least four times in the postoperative period in each case. The postoperative period ranged from 16 to 43 months. Our observations demonstrated that intraocular implants produce a greater magnitude of endothelial cell damage and iris-supported lenses have a more deleterious effect on the corneal endothelium compared with anterior chamber lenses. Seventy-one percent of the eyes with intraocular implants demonstrated precipitates on the endothelium with 16% developing guttata-like areas. All these changes were progressive with time with no such phenomenon occurring in eyes with simple cataract extractions. The progressive endothelial cell damage may be a sequel of chronic, smoldering uveitis associated with intraocular implants.

Deposits resembling foreign-body giant cells, which can be seen on specular reflex slit-lamp examination, were studied in vivo with a wide-field specular microscope using a low-power dipping cone lens in three cases of posterior chamber lens implantation. The deposits seen as iris pigment on routine examination showed two types of cell-like figures: round, bipolar or ameboid small figures with long branching processes and round, oval, or bizarre large figures. The large cell type had the pigment particles at the central or paracentral area and vacuole-like structures adjacent to the pigment particles. The specular photomicrographic characteristics were similar to those of fibroblast-like cells and foreign-body giant cells, which had been shown on the surfaces of extracted implanted intraocular lenses by the lens implant cytology technique.

Accurate thickness measurements in vivo and in vitro of penetrating keratoplasties in rabbits over a period of time and when evaporation is prevented, show that many grafts, which are deemed successful on clinical criteria, are in fact failures. The specular microscope was used to measure the thickness of grafts under silicone fluid and revealed that integral autografts that clinically appeared successful maintained a constant close-to-normal thickness, while endothelium-free grafts which also appeared successful, swelled rapidly. Hence a clear graft is not necessarily a satisfactory one. Evaluation of experimental donor corneas by their fate after transplantation is invalid unless their physiological powers of deturgescence are clearly demonstrated. Clinical evaluation and intermittent thickness measurements cannot distinguish success from failure of corneal grafts in rabbits. Tarsorrhaphy or contact lenses to prevent evaporation are inadvisable in this animal.

Fifteen patients who had had a successful penetrating keratoplasty were photographed with the clinical specular microscope and the resulting endothelial photomicrographs were analyzed. The average endothelial cell area was one to six times larger and the average endothelial cell perimeter was one to 2 1/2 times larger than that of a normal cornea of a subject the same age as the donor. In each corneal graft, endothelial cell areas and perimeters clustered tightly around a mean value, although the mean value for different corneas varied significantly. The thickness and transparency of each graft was normal, indicating that within the observed limits the success of the transplantation procedure did not depend on final endothelial cell size or perimeter.

Summary This presentation supports many of the findings described by Dr Chandler. Pathologic findings with light microscopy have led us toward some understanding of the damage produced by proliferating tissues. Transmission and scanning electron microscopy may help us to further understand the pathogenesis. At this stage, we believe the specular microscope may be useful in cases of unexplained unilateral glaucoma with subtle endothelial abnormalities undetected by slitlamp examination. It may, in the future, facilitate the differentiation of these interesting endothelial dystrophies with their accompanying glaucomas.

Changes in the specular microscopical appearance of the corneal endothelium are induced by the application of glycerin drops, in clinically used concentrations, to the epithelial surface of living rabbit corneas. Many of the affected cells appear to recover but a large number fall away and are replaced by the spread of neighbouring cells, eventually to leave no trace of their loss. The processes involved are described as seen and photographed in vivo with a modified, “roving”, specular microscope over prolonged periods of observation. The reduction in cell population results in no demonstrable loss of functional efficiency of the endothelium as evaluated by the temperature reversal phenomenon in vitro, after a period of cooling the eyes to 4°C. However, urethane anaesthesia is shown to be suspect in interfering with the pump-leak mechanisms of the endothelium.

Studies were made on the effects of hydrostatic pressure on the hydration of intact, de-epithelialized, de-endothelialized and denuded corneas mounted for specular microscopy and perfused with normal Ringer of perfused with bicarbonate and carbon dioxide-free Ringer which is claimed to “switch off” the endothelial pump. Rapid transient changes in thickness of any cornea are caused by rapid changes in hydrostatic pressure during an experiment such that, for example, an increase in hydrostatic pressure causes a decrease in corneal thickness before any subsequent effects are seen. Hydrostatic pressures below about 50 cm water have negligible effect (other than that of transient thickness change with rapid change in hydrostatic pressure) on the hydration of corneas with an intact epithelium whatever the condition of the endothelium, that is, in de-endothelialized preparations as well as in intact corneas with pumping or with non-pumping endothelia. If a cornea has no epithelium, hydrostatic pressure can balance the swelling pressure of the stroma to maintain a constant thickness in the absence of a pumping endothelium, that is, “equilibrium” thicknesses occur in denuded corneas (bare stroma), and in de-epithelialized corneas with endothelial pump “switched off”, which are related to the applied hydrostatic pressure. Hydrostatic pressure alone can act to deturgesce swollen de-epithelialized corneas whether the endothelial pump is “switched on” or is “switched off” or the endothelium removed. These findings are discussed in relation to corneas swollen considerably (>25%) above physiological thickness as often encountered in long-term refrigerated or cryopreserved preparations.

Specular microscopy performed six months postoperatively on 122 lens implant patients showed that endothelial cell loss rates varied according to method of cataract extraction and type of lens implant. Phacoemulsification with implantation of a Platina-style lens was associated with the highest cell loss; planned extracapsular cataract extraction with implantation of a Choyce-style or J-loop lens was associated with the lowest cell loss. The presence of marked striate keratopathy on the first postoperative day was directly related to endothelial cell loss.