Aim: To examine the distribution of melatonin 1a (MT1) receptors in the human eye. Methods: Seven normal human eyes were examined by immunohistochemical staining of paraffin sections, using an anti-MT1 primary antibody and an ABC detection system. Results: MT1 receptor immunoreactivity (MT1-IR) was detected primarily in the inner segments of rods and cones and in retinal ganglion cells. In addition, MT1-IR was present in the adventitia of retinal arteries and veins, including the papillary region, but absent in ciliary and choroidal vessels. Mild staining of corneal endothelial cells and keratocytes was observed in all but two eyes. Conclusion: MT1-IR is present in various ocular tissues with the highest density in photoreceptor cells and ganglion cells. The physiological function of these receptors deserves further investigation.

We present the features of a malignant tumor of the RPE with unequivocal extraocular extension. These findings raise the possibility that RPE hyperplasia may transform into a malignant tumor.

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Na+/Ca2+ exchanger of the cardiac type is present in human retina and RPE. The variation in immunoreactivity among the different specimens may reflect the different diseases of these eyes and their different metabolic states. A specific relation between certain diseases and malfunction of the Na+/Ca2+ exchanger could have a major impact on therapeutic regimens.

Purpose Reactive lymphoid hyperplasia (RLH), also called inflammatory pseudotumor, benign lymphoma or pseudolymphoma, is a benign and reversible enlargement of lymphoid tissue probably as a reaction to antigen hyperstimulation. RLH consists of dense sheets of small mature lymphocytes with the formation of primary and secondary follicles reminiscent of normal lymph node architecture. In this study we wanted to evaluate the clinical presentation of RLH on the ocular surface. Methods We reviewed 6 patients (3 males, 3 females) with RLH of the ocular surface. The mean age at the time of diagnosis was 28 yrs (range: 8 to 77 yrs). Paraffin sections were stained with H&E and PAS and further evaluated using immunohistochemistry. Results In 2 patients, RLH was confined to the caruncle. One patient presented with a large cyst‐like lesion, another one with a conjunctival nodule near the medial canthus, and in the oldest patient the RLH manifested itself as a pemphigoid‐like conjunctival lesion in the lower fornix. A 26‐years old female patient with a Non‐Hodgkin‐Lymphoma of the left conjunctiva developed conjunctival RLH one month later in the lower fornix of the fellow eye. Follow‐up (1‐11 yrs) was uneventful in all patients. Conclusion In our case series, RLH presented as a singular lesion with varying clinical morphology. Obviously, it has to be carefully distinguished from lymphoma and should be considered in the differential diagnosis even of cyst‐like lesions and at unusual sites such as the caruncle.