The reluctance of human corneal endothelial cells (HCECs) to divide has continually intrigued investigators. Related to this, the discovery of an increased endothelial cell population in the periphery of the human cornea has prompted an investigation for evidence of the existence of stem-like cells in the endothelial periphery. Researchers at the University of Alabama and Emory University (Atlanta) conducted a study aimed at showing that stem cells or transient amplifying cells may exist in the periphery of the cornea, which might explain the origin of HCECs and indicate a source for these cells in wound repair.

The researchers obtained human corneas with attached scleral rims from eye banks and assayed them for telomerase activity and bromodeoxyridine (BrdU) incorporation to determine, respectively, the presence of a stem-like cell marker and replicative activity. In the case of telomerase activity, they divided the tissues into central, intermediate and peripheral areas using trephines. They performed BrdU staining on whole corneas plus scleral rims exposed to BrdU antibodies on the endothelial side, whereas BrdU fluorescence was obtained from transverse sections of the these tissues by the same procedure. Some corneas were wounded to determine whether the wounded areas stimulated BrdU (by staining or fluorescence) followed by the synthesis of transforming growth factor beta (TGF-beta). The latter was determined by quantitative ELISA. Rabbit corneas were also assayed for BrdU incorporation to compare their evidence of cell division with that of humans.

After corneas were divided into central, intermediate and peripheral sections, the dissected endothelial tissues exhibited positive telomerase activity in the peripheral and intermediate sections. There was no activity in the central endothelial tissues or the limbus between the trabecular meshwork and Schwalbe's line. BrdU staining with alkaline phosphatase was occasionally observed in the wounded area's human corneal endothelial cells after wounding. When BrdU fluorescence assays were made on corneal transverse sections with fluorescein, fluorescence occurred in an area just at and adjacent to the trabecular meshwork, but was not at the corneal endothelium. After wounding, BrdU fluorescence extended into the corneal endothelium. TGF-beta levels were increased in fluids bathing the endothelium following wounding, but the increases lagged behind the wounding event.

The authors suggest that stem-like cells may be sequestered in a niche at the junctional region where the corneal endothelial cells and the trabecular meshwork come together. These putative stem cells may supply new cells for both the corneal endothelium and the trabeculae. Evidence suggests that cells from this area migrate (perhaps as transient amplifying cells) to the endothelial periphery and, perhaps, to wounded areas of the corneal endothelium when needed. The migration may not be constant and may be age dependent.

This study sought to evaluate ultrasound biomicroscopy (UBM) in the management of anterior segment tumors. Investigators conducted a retrospective analysis of medical records of consecutive patients referred to the ocular oncology unit, University of California-San Francisco (UCSF), for suspected anterior segment tumors from 1999 to 2004.

The researchers evaluated 132 eyes from 130 patients, which included 55 uveal melanomas (UM), 21 iris nevi, 30 iris cysts and 26 remaining lesions. Of the melanomas, 45 were also evaluated with conventional A/B-scan. There was 29 percent correspondence between the anatomical structures invaded by melanoma as identified by B-scan vs. disease extent defined by UBM. Ciliary body and peripheral iris involvement by melanomas was significantly more frequently observed by UBM than B-scan. Seven of 30 benign cysts were diagnosed as cystic before UBM evaluation. In three cases, neuroepithelial cysts were associated with intercurrent pathology including iris nevus (two cases) and ciliary body melanoma (one case). Two ciliary body melanomas showed cavitation, including one patient with a pseudocyst. Histopathological correlation was possible in six cases.

The authors believe their results show that UBM is an indispensable tool for managing anterior segment tumors. They maintain that the study demonstrates the superiority of UBM vs. conventional B-scan for the precise localization of uveal melanoma, especially involving the ciliary body and peripheral iris.

The University of California-Davis conducted this study of the Ocular Hypertension Treatment Study (OHTS) results to compare the occurrence of normal visual field (VF) test results following two vs. three consecutive, abnormal and reliable test results in OHTS.

Sixty-four participants (68 eyes) out of a total of 1,636 participants in OHTS developed a VF primary open-angle glaucoma (POAG) end point. Investigators compared the proportion of normal VF test results after a VF POAG end point among eyes whose VF abnormality was confirmed by two (nine eyes) vs. three (59 eyes) consecutive, abnormal and reliable VF test results.

The proportion of VF test results that were normal subsequent to a VF POAG end point in eyes whose abnormality was confirmed by two consecutive, abnormal and reliable test results was significantly higher (73 of 110, or 66 percent) compared with eyes whose abnormality was confirmed by three consecutive, abnormal and reliable test results (46 of 381, or 12 percent). The authors of this study conclude that a VF POAG end point confirmed by three consecutive, abnormal and reliable VF test results appears to have greater specificity and stability than either one or two consecutive, abnormal and reliable VF test results. However, some eyes whose VF POAG end point was confirmed by three consecutive, abnormal, reliable test results nonetheless had one or more normal test results on follow-up.

The Confocal Scanning Laser Ophthalmoscopy (CSLO) Ancillary Study to the Ocular Hypertension Treatment Study, conducted by University of San Diego’s Hamilton Glaucoma Center and Diagnostic Imaging Laboratory, aimed to determine whether baseline CSLO optic disc topographic measurements are associated with the development of primary open-angle glaucoma (POAG) in individuals with ocular hypertension.

A total of 865 eyes from 438 participants who had good-quality baseline CSLO images were included in this study. Each baseline CSLO parameter was assessed in univariate and multivariate proportional hazards models to determine its association with the development of POAG.

Forty-one eyes from 36 CSLO Ancillary Study participants developed POAG. Several baseline topographic optic disc measurements were significantly associated with the development of POAG in both univariate and multivariate analyses, including larger cup-disc area ratio, mean cup depth, mean height contour, cup volume, reference plane height, smaller rim area, rim area to disc area and rim volume. In addition, classification as "outside normal limits" by the Heidelberg Retina Tomograph classification and the Moorfields Regression Analysis classifications (overall, global, temporal inferior, nasal inferior and superior temporal regions) was significantly associated with the development of POAG. Within the follow-up period of this analysis, the positive predictive value of CSLO indexes ranged from 14 percent (Heidelberg Retina Tomograph classification and Moorfields Regression Analysis overall classification) to 40 percent for Moorfields Regression Analysis temporal superior classification.

The authors of this study believe that longer follow-up is required to evaluate the true predictive accuracy of CSLO measures.