Shear behavior of bovine scleral tissue.

Ocular tissue properties have been widely studied in tension and compression for humans and a variety of animals. However, direct shear testing of the tissues of the sclera appear to be absent from the literature even though modeling, analyses, and anatomical studies have indicated that shear may play a role in the etiology of primary open angle glaucoma (POAG). In this work, the mechanical behavior of bovine scleral tissue in shear has been studied in both out-of-plane and in-plane modes of deformation. Stress-strain and relaxation tests were conducted on tissue specimens at controlled temperature and hydration focusing on trends related to specimen location and orientation. There was generally found to be no significant effect of specimen orientation and angular location in the globe on shear stiffness in both modes. The in-plane response, which is the primary load carrying mode, was found to be substantially stiffer than the out-of-plane mode. Also, within the in-plane studies, tissue further from the optic nerve was stiffer than the near tissue. The viscosity coefficient of the tissue varied insignificantly with distance from the optic nerve, but overall was much higher in-plane than out-of-plane.

Examination of the anterior uveoscleral pathway in domestic species.

OBJECTIVE: To investigate the uveoscleral (US) pathway in the normal eyes of four domestic spp.: the cat, pig, cow and horse by examining the comparative anatomical structure of anterior US pathway. ANIMALS STUDIED: Four cats, ten pigs, four cows, eight horses. PROCEDURES: Formalin-preserved specimens from anterior uveas of the cat, pig, cow and horse were embedded and serially sectioned sagittally and tangentially and stained with H&E, Masson's trichrome, smooth muscle actin immunolabel, or elastin stain. RESULTS: Spaces between the endings of the outer anterior ciliary body musculature (CBM) formed avenues for the beginning of the US pathway and varied in the amount of extracellular matrix (ECM) material being most developed in the pig. In the cow, other anterior muscle bundles attached the CBM to the sclera concomitant with the presence of an anterior elastic sheath. In the horse, these muscle bundles were connected to branching connective tissue trabeculae within the US pathway that were attached radially to the sclera. In the cat, muscle bundles were more abundant and formed a fine meshwork of trabecular associations with the posterior ICA. Supraciliary development was most pronounced in the horse and least in the pig. CONCLUSION: All species possessed clearly developed and unique US pathways. The outermost muscle bundles of the CBM appeared to have close interaction with the US pathway and the degree of these muscle associations differed with species. The species specific anatomical variations within the US pathway could play a pivotal role in the variability of aqueous outflow along this pathway.

Diffuse corneoscleral limbal neuromas with prominent corneal nerves in multiple endocrine neoplasia syndrome type IIB.

This report describes a 7-year-old boy with multiple endocrine neoplasia type 2B who presented to the ophthalmology department because of peripheral corneal changes. In addition to prominent corneal nerves and eyelid neuromas, the patient was found to have substantial corneoscleral limbal thickening with corneal neovascularization.

Comparison of the trabecular meshwork length between open and closed angle with evaluation of the scleral spur location.

This study analysed the trabecular meshwork (TM) length in open and closed angle patients and presented a better method for locating the scleral spur using Schwalbe's line method in anterior segment optical coherence tomography (AS-OCT). Patients who underwent AS-OCT at Yonsei University Gangnam Severance Hospital we enrolled; 58 and 57 open and closed angle eyes, respectively. We measured the distance from the scleral spur to Schwalbe's line as the TM length and compared it between open and closed angle patients, and to previous studies. TM length was applied to locate the scleral spur using Schwalbe's line method. Mean TM lengths were 811 ± 83 µm and 575 ± 96 µm in the open and closed angle groups, respectively (p < 0.001). Comparing the actual TM heights using Schwalbe's line method with an updated reference distance significantly increased accuracy to locate the scleral spur (open: 811 µm, closed: 575 µm) when compared with the 1000 µm reference distance (p < 0.001). TM length was significantly different between open and closed angle patients. Further, the reference distance for Schwalbe's line method should be distinguished according to open and closed angle eyes in order that the scleral spur can be located properly.

Nerve terminals at the human corneoscleral limbus.

AIMS: To demonstrate and characterise distinct subepithelial compact nerve endings (CNE) at the human corneoscleral limbus. METHODS: Ten fresh human donor corneoscleral discs (mean age, 67 years) and 26 organ-cultured corneoscleral rims (mean age, 59 years) were studied. All samples were subjected to enzyme histochemical staining related to endogenous acetylcholinesterase present in nerve tissue and H&E staining. Whole-mount en face imaging with NanoZoomer digital pathology microscope and serial cross-section imaging with light microscope were undertaken. RESULTS: Nerves entering the corneoscleral limbus and peripheral cornea terminate under the epithelium as enlarged multiloculated and multinucleated ovoid structures within a 2 mm zone. They are closely associated with the rete pegs of the limbal palisades and the limbal epithelial crypts, often located within characteristic stromal invaginations of these structures. Their numbers ranged from 70 to 300 per corneoscleral rim. The size ranged from 20 to 100 µm. They had one or more nerve connections and were interconnected to other similar endings and to the limbal nerve plexus. CONCLUSION: Human corneoscleral limbus demonstrates a population of nerve terminals resembling CNE with distinct morphological features. They are closely associated with the limbal stem cell niches, suggesting a potential contribution to the niche environment.

Promotion of angiogenesis in tissue engineering: developing multicellular matrices with multiple capacities.

One of the aims of tissue engineering is to be able to develop multi-tissue organs in the future. This requires the optimization of conditions for the differentiation of multiple cell types and maintenance of the differentiated phenotype within complex engineered tissues. The goal of this study was to develop prototype tissue engineered matrices to support the simultaneous growth of different cell types with a particular focus on the angiogenic process. We examined two different matrix compositions for the promotion of blood vessel and tube formation. A fibrin-based matrix with the addition of a combination of growth factors supported vascular growth and the invasion of inflammatory cells. Using this fibrin matrix, in combination with a collagen-based hydrogel, a simple in vitro model of the cornea with adjacent sclera was developed that was complete with innervation and vascular structures. In addition, we showed that collagen-based matrices were effective in delivering mononuclear endothelial progenitor cells to ischemic tissue in vivo, and allowing these cells to incorporate into vascular structures. It is anticipated that with further development, these matrices have potential for use as delivery matrices for cell transplantation and for in vitro study purposes of multiple cell types.

Angioarchitecture and innervation of the primate anterior episclera.

PURPOSE: To investigate the primate episcleral vasculature and its innervation with respect to morphological specializations. METHODS: Serial sections of the anterior episclera of 8 monkey eyes and 20 human eyes were investigated enzyme- and immunohistochemically using antibodies against smooth-muscle alpha-actin (SMA), neurofilament, synaptophysin, substance P (SP), calcitonin gene-related peptide (CGRP), vesicular acetylcholine transporter (VACHT), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), tyrosine hydroxylase (TH), vesicular monoamine transporter II (VMAT II), as well as the NADPH-diaphorase reaction. Arteriovenous anastomoses (AVA) were quantified. RESULTS: All episcleral vessels including veins showed intense staining for SMA. Capillary loops were only seen in the limbal arcades, not in the episclera itself. Instead, AVA connected the episcleral arteries with the veins, which formed an interlacing vascular network. In the monkey episclera, 4-6/mm2 AVA were found; in the human episclera, 0.5-1/mm2. Numerous nerve endings staining for NADPHd (NADPHdiaphorase) and TH surrounded all episcleral vessels including anastomoses and veins. NPY, VIP, and VACHT-immunoreactive (IR) nerve terminals were less numerous. CGRP and SP-IR terminals were seen both at the vessels and in the intervascular connective tissue. CONCLUSIONS: The episcleral vasculature shows a specialized morphology with absence of capillaries, numerous arteriovenous anastomoses, a muscle-rich venous network, and intense innervation by vasodilative and vasoconstrictive nerves. This might allow regulation of blood flow and volume in the episcleral vessels and Voigt's capillaries for thermoregulation and modulation of episcleral venous pressure and thereby outflow facility.

Three-dimensional reconstruction of scleral cold thermoreceptors of the cat eye.

Sensory endings that respond to local cooling were identified electrophysiologically in the cat's sclera. Functionally identified scleral thermal fibers were then used to analyze the structural characteristics of cold receptor endings. Four Adelta units sensitive to controlled cooling of their scleral receptive fields were recorded. The receptive areas were mapped, demarcated with pins and examined electron microscopically using extensive three-dimensional reconstructions. The supporting tissue within the receptive areas of cold units consisted of dense collageneous tissue with a small number of blood vessels that were either veins or capillaries. Adelta nerve fibers were found within these tissue blocks presumably corresponding with cold sensitive fibers. Small nerves and single nerve fibers devoid of a perineurium were found in all parts of the tissue, only occasionally passing a blood vessel. The terminal portions showed axonal swellings all along the unmyelinated segment filled with mitochondria, glycogen particles, and some vesicles. About 30% of the terminal axonal membrane is not covered by Schwann cells. In the unmyelinated distal portion, the mitochondrial content ranged from 0.012 to 0.038 microm(3) mitochondrial volume per microm(2) nerve fiber membrane. In comparison with sensory endings in the cat's knee joint, cold receptors in the cat sclera showed many similarities in their three-dimensional structure with polymodal nociceptor endings of the knee joint but contain less mitochondria. This suggests that cold sensory endings do not require specialized cellular processes for the transduction of cold stimuli, as is the case for multimodal transduction and sensitization in the terminal portion of polymodal nociceptors.

Substance P-like immunoreactive nerves in the anterior segment of the rabbit, cat and monkey eye.

The indirect immunofluorescence technique demonstrates a substance P-like immunoreactive innervation to the anterior segment of the rabbit, cat and monkey eye. In all three species there is a sparse, but definite, corneal innervation. For the rabbit, substance P-like immunoreactive nerves to the aqueous outflow apparatus are found chiefly in the pectinate ligament. In the cat, this innervation is somewhat more extensive, being seen in the septae of the ciliary cleft as well. The monkey has a more plentiful innervation to the outflow apparatus than either the cat or the rabbit. Substance P-like immunoreactive nerves are visible in the trabecular meshwork and at the inner and outer walls of Schlemm's canal. For all three animals, the iris contains immunoreactive nerve fibers to the sphincter muscle, to the large blood vessels and to the anterior stromal melanocytes. In the ciliary body, the ciliary processes receive a constant innervation; it is somewhat more dense in the rabbit. Some of the large ciliary body blood vessels also are innervated. Ciliary body melanocytes are innervated; it was not possible to determine whether or not immunoreactive fibers innervate the ciliary muscle cells as well. The present study extends prior knowledge of the innervation of the eye. Taken with the known physiologic effects of substance P, it indicates a series of potential roles for this peptide in the vegetative processes of the eye.

Activation of scleral cold thermoreceptors by temperature and blood flow changes.

PURPOSE: To study the response of scleral cold receptors located in areas of the eye unexposed to temperature and blood flow changes. METHODS: In anesthetized cats, the neural activity was recorded from single, cold-sensory fibers of the ciliary nerves innervating the sclera and limbus. Controlled temperature changes of the receptive field were performed with a contact thermode. Ocular blood flow reductions were obtained by occluding the ipsilateral common carotid artery for 30 to 60 seconds with a compressor placed around the artery. Local blood flow was measured with a laser Doppler flowmeter. Temperature was measured with a microprobe introduced in the subscleral space. Ocular sympathetic stimulation was performed with a pair of silver electrodes placed on the preganglionic cervical sympathetic trunk. To induce local hypoxia, N(2) was applied on the scleral surface with a specially designed chamber. For systemic hypoxia the breathing air was replaced with a gas mixture containing 10% O(2) in N(2). RESULTS: Sensory nerve fibers identified as cold receptors exhibited ongoing nerve activity in bursts at 35 degrees C and responded to cooling pulses applied to their receptive fields with an increase in the impulse discharge that reached a peak and decayed gradually to a lower level. When temperature was reduced from 35 degrees C to 34 degrees C, frequency increased monotonically with decreasing temperature of the sclera. Between 35 degrees C and 30 degrees C, peak and mean frequencies were roughly proportional to temperature of the sclera. The characteristics of burst discharges also depended on scleral temperature. Electrical stimulation of the cervical sympathetic trunk induced a decrease in blood flow and temperature and evoked an increase in the firing frequency of cold-sensory fibers that was proportional to the frequency of stimulating pulses. Carotid occlusion also elicited an increase of the discharge of cold thermoreceptor fibers that occurred in parallel with a decrease in blood flow and temperature in the receptive field area. Local or systemic hypoxia did not modify appreciably the spontaneous firing frequency of scleral cold-sensory fibers. CONCLUSIONS: Scleral and episcleral cold-sensory fibers encoded as a change in their impulse frequency and firing pattern temperature reductions of less than 1 degrees C in scleral tissues. Activation of scleral and episcleral cold-sensory fibers by sympathetic vasoconstriction and acute arterial pressure reductions appear to be secondary to the temperature decrease that accompanies the reduction in ocular blood flow caused by these maneuvers. Scleral thermosensory fibers are located in ocular territories not directly exposed to external temperature changes. Thus, the sensory information on local blood flow variations provided by these receptors may be involved in a reflex regulation of choroidal blood flow that functions to maintain a constant temperature and blood supply to the retina.

Failure of increased intracranial pressure to affect rapid axonal transport at the optic nerve head.

In owl monkeys, elevation of intracranial pressure to 500 mm. saline for 4 to 7 hours failed to cause an accumulation at the optic nerve head of protein carried by rapid axonal transport. This suggests that the block of rapid transport observed by others during papilledema may be the result of axon swelling, not its cause. Alternatively, more than 8 hours may be required for intracranial pressure to show an effect, only the slow transport may be affected initially, or other factors than simple hydrostatic pressure may be operative in papilledema. In addition, the elevated intracranial pressure did not prevent the block of axonal transport at the lamina cribrosa produced by elevated intraocular pressure, even though the elevated intracranial pressure reduced the pressure gradient to which the axon is subjected as it crosses the lamina cribrosa. Perhaps the block produced by intraocular pressure is not due to a simple mechanical or hydrostatic mechanism.

Orthograde and retrograde axoplasmic transport during acute ocular hypertension in the monkey.

Orthograde and retrograde axoplasmic transport have been studied in the optic nerve heads of 37 Macaca fascicularis eyes with normal or elevated intraocular pressure (IOP) produced by cannulation of the anterior chamber. Orthograde transport was labeled by 3H-amino acids injected intravitreally and incorporated into retinal ganglion cell proteins. Retrograde transport was studied in the same eyes by injecting horseradish peroxidase (HRP) into one or both optic tracts and dorsal lateral geniculate nuclei (dLGN). Both tracers accumulated in the lamina scleralis (LS) of eyes maintained at pressures of 25 to 150 mm. Hg for 12 to 28 hours (pressure in normal controls = 10 to 14 mm. Hg) but the HRP technique was markedly more sensitive. The degree of retrograde transport obstruction in the LS appeared to be directly proportional to both the height and the duration of elevated IOP. In one experiment, the blockades of orthograde and retrograde transport induced at 50 mm. Hg were demonstrated to be reversible. Serial reconstructions of radioautographs and peroxidase-reacted sections of the optic nerve heads demonstrated that the orthograde and retrograde transport obstructions were coincidental anatomically by light microscopy in the LS and occurred most prominently in the temporal quadrants of the nerve head. These transport obstructions occurred at moderate elevations of IOP (25 TO 50 mm. Hg) despite (1) elevated arterial PO2 levels during inhalation of 100 percent oxygen and (2) intact nerve head capillary circulation, as demonstrated by perfusion with nucleated avian erythrocytes.

Nerve endings with structural characteristics of mechanoreceptors in the human scleral spur.

PURPOSE: The innervation of the scleral spur region was investigated to learn whether mechano-receptors are present in this region. METHODS: Serial tangential sections and whole-mount preparations of the scleral spur region of 18 human eyes of different ages were investigated with electronmicroscopic and immunohistochemical methods. For immunohistochemistry antibodies against neurofilament-proteins, synaptophysin, substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), tyrosine-hydroxylase, dopamine-beta-hydroxylase, and acetylcholinesterase were used. RESULTS: Club- or bulb-shaped nerve endings with a diameter of 5 microns to 25 microns were identified in the scleral spur region throughout the whole circumference of the eyes. The terminals derive from myelinated axons with a diameter of approximately 3 microns and stain with antibodies against neurofilament-proteins and synaptophysin but do not stain for tyrosine-hydroxylase, dopamine-beta-hydroxylase, acetylcholinesterase, NPY, VIP, SP, or CGRP. Electronmicroscopically, the endings contain abundant neurofilaments, granular and agranular vesicles of different sizes, numerous mitochondria, and lysosome-like lamellated structures. The endings are incompletely ensheathed by Schwann cells. Those areas of the cell membrane of the endings that are not covered by Schwann cells are in intimate contact with the fibrillar connective tissue elements of the scleral spur. CONCLUSION: These structural features are highly characteristic for mechanoreceptive nerve endings in other tissues of the human body. The authors therefore hypothesize that the club-or bulb-shaped nerve endings in the human scleral spur are afferent mechanoreceptors that measure stress or strain in the connective tissue elements of the scleral spur. Such changes might be induced by ciliary muscle contraction and/or by changes in intraocular pressure.

Innervation of myofibroblast-like scleral spur cells in human monkey eyes.

PURPOSE: To study the innervation of the presumably contractile, myofibroblast-like scleral spur cells in human and cynomolgus monkey eyes. METHODS: Serial tangential sections of the scleral spur region of the eyes of 16 human donors and 6 cynomolgus monkeys were investigated with immunocytochemical methods. Antibodies against acetylcholinesterase, synaptophysin, alpha-smooth muscle actin, calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), nitric oxide synthase (NOS), substance P (SP), tyrosine hydroxylase (TH), and vasoactive intestinal peptide (VIP) were used. In addition, sections were processed for glyoxylic acid-induced catecholamine fluorescence (CF) and for NADPH-diaphorase (NADPH-d). RESULTS: In the eyes of both species, circumferentially oriented varicose axons were observed in the scleral spur region of all quadrants. Double labeling showed that most of these scleral spur axons were in close contact with the alpha-smooth muscle actin-positive, myofibroblast-like scleral spur cells. In human eyes, the axons showed like-immunoreactivity (LI) for SP, CGRP, NPY, VIP, and NOS. In addition, numerous scleral spur axons stained for NADPH-d. Most SP-LI scleral spur axons were double-labeled for CGRP-LI, and none for VIP-LI. All NPY-LI scleral spur axons were double labeled for VIP-LI but lacked immunoreactivity to TH. Some VIP-LI axons were not labeled for NPY-LI. Nerve fibers immunoreactive (IR) for TH or positively stained for CF were not observed in association with scleral spur cells. In contrast, in cynomolgus monkey eyes, circumferentially oriented TH-IR and CF-positive varicose axons were observed frequently in the scleral spur region. In addition, SP-LI, CGRP-LI, and NPY-LI/TH-IR axons were present in the chamber angle of monkey eyes, whereas VIP-LI, VIP-LI/NPY-LI, NOS-positive, or NADPH-d-positive nerve fibers were absent. In both species, positive staining for acetylcholinesterase was seen only in the ciliary muscle, not in the scleral spur region. CONCLUSIONS: The close association of varicose axons with the myofibroblast-like scleral spur cells indicates that nervous signals modulate scleral spur cell tone. A sympathetic scleral spur cell innervation is present only in cynomolgus monkeys but seems to be absent in humans. Conversely, scleral spur axons of presumably parasympathetic origin (NOS-IR or NADPH-d-positive, VIP-LI, and VIP-LI/NPY-LI) are absent in the cynomolgus monkeys but present in humans. In both species, a cholinergic innervation of the scleral spur cells seems to be rare or absent.

Efferent and afferent innervation of primate trabecular meshwork and scleral spur.

PURPOSE: To determine the correlation between nerve terminals and cells or extracellular matrix (ECM) components in different portions of the primate trabecular meshwork (TM) and scleral spur (SS). METHODS: Serial sagittal and tangential sections through the anterior segments of 10 cynomolgus monkey eyes and 12 human eyes were investigated immunohistochemically with antibodies against the vesicular acetylcholine transporter (VACHT), vasoactive intestinal polypeptide (VIP), tyrosine-hydroxylase (TH), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP), and galanin (GAL) and with a reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPHd) reaction. The distribution of the terminals was compared with that of alpha-smooth-muscle actin (SMA) staining in TM and SS. The relationship between terminals and adjacent cells or ECM components was also studied in ultrathin sections through the TM and SS of 11 monkey eyes cut in sagittal, tangential, and frontal planes. RESULTS: NADPHd-positive nerve terminals were present, especially in the outer portion of both human and monkey TM and in the SS. VACHT-immunoreactive (IR) fibers were found in human but not in monkey SS and TM. The fibers were most numerous in the elongated SS and posterior TM where most cells also stained for SMA. SP- and CGRP-IR nerve endings were also more numerous in the outer TM and SS than in the inner TM. Ultrastructurally, staining for SP was seen in nerve endings containing mitochondria and dense core vesicles and was in contact with the cribriform elastic network. In the posterior SS of monkey eyes were large terminals similar to those previously described in human eyes. CONCLUSIONS: The results show for the first time that in the primate TM and SS, there are cholinergic and nitrergic nerve terminals that could induce contraction and relaxation of TM and SS cells. Terminals in contact with the elastic-like network of the TM and containing SP-IR resemble afferent mechanoreceptor-like terminals in other parts of the body. These findings raise the possibility that the TM may have some ability to self-regulate aqueous humor outflow.

The anatomy at the lamina cribrosa in the normal cat eye.

In normal cat eyes, the mean cross-sectional area of the nerve fiber bundles is greater in the temporal than in the nasal lamina cribrosa. The area occupied by the interbundle trabeculae is less in the temporal sectors than in the nasal sectors of the nerve. The number and the shape of the laminar pores are similar in all nerve sectors.

Intrascleral nerve loop mistakenly identified as a foreign body.

A 5-year-old boy had an excisional biopsy of a pigmented scleral lesion thought clinically to be a foreign body, probably graphite from a pencil. Histological study demonstrated that the pigmented lesion was an intrascleral nerve loop (Axenfeld).

Axonal transport interruption and anatomy at the lamina cribrosa.

Pressure-induced, focal axonal transport abnormalities were studied in 14 cat eyes by the examination of serial step-section tissue radioautogram. Although the patterns of the transport interruption at the lamina cribrosa varied from eye to eye, the temporal sectors of the nerve head were most often involved by this abnormality. The anatomy at the lamina cribrosa was studied in adjacent (6 micrometers) cross-sectional specimens. The thickness of the extra-bundle trabeculae and the nerve fiber bundle dimensions including the cross-sectional area and the number and the shape (the ratio of the major and the minor axis diameters) of the laminar pores were measured by computer-assisted perimeter analysis. There was no correlation between the location of the transport interruption and any of these anatomic measurements.

Axon deviation in the human lamina cribrosa.

AIMS: To examine the course taken by individual retinal ganglion cell axons through the human lamina cribrosa. METHODS: Retinal ganglion cell axons were labelled using the retrograde tracer horseradish peroxidase applied directly to the optic nerve in two normal human eyes removed during the course of treatment for extraocular disease. RESULTS: A majority of axons took a direct course through the lamina cribrosa but a significant minority, in the range 8-12%, deviated to pass between the cribrosal plates in both central and peripheral parts of the optic disc. CONCLUSIONS: It is postulated that these axons would be selectively vulnerable to compression of the lamina cribrosa in diseases such as glaucoma in which the intraocular pressure is increased.

Expression of protein gene product 9.5 in lepromatous eyes showing ciliary body nerve damage and a "dying back" phenomenon in the posterior ciliary nerves.

BACKGROUND/AIM: Peripheral nerve destruction is the hallmark of leprosy. Ocular complications form a substantial part of the clinical manifestations but histopathology of nerve destruction within ocular structures has not been shown satisfactorily. The role of protein gene product (PGP) 9.5 in identifying nerve destruction in the ciliary body and posterior ciliary nerves of lepromatous eyes is shown. METHODS: Serial sections from two lepromatous eyes and two non-lepromatous eyes were stained with PGP 9.5. Histopathological comparison was done on the expression of the PGP 9.5 stain in nerves within the ciliary body, posterior ciliary nerves adjacent to the optic nerve, and nerves tracking through the sclera. RESULTS: In non-lepromatous eyes, PGP 9.5 was expressed in nerves within the ciliary body, the nerves within the sclera, and posterior ciliary nerves adjacent to the optic nerve. In lepromatous eyes no PGP 9.5 was expressed, signifying nerve destruction. CONCLUSIONS: Nerve destruction in lepromatous eyes has been confirmed histopathologically by the absence of or patchy staining with PGP 9.5. Nerve destruction in the ciliary body can extend to the posterior ciliary nerves by an ascending axonopathy. This "dying back" phenomenon is akin to the "glove and stocking" anaesthesia found in lepromatous leprosy.