Thaer Alomar

In vivo confocal microscopic findings in patients with limbal stem cell deficiency

Aim To describe in vivo confocal microscopy (IVCM) findings in patients with limbal stem cell deficiency (LSCD). Methods 23 eyes of 17 consecutive patients suffering from LSCD were included in this study. A detailed examination by IVCM was performed in addition to a routine slit-lamp biomicroscopy. Size and density of corneal epithelial and conjunctival epithelial cells on cornea were measured and statistically analysed using SPSS version 8.0 software. Results were compared with histology in select cases. Results Anatomical and morphological differences were observed between normal corneal cells and conjunctival epithelial cells on cornea. Size and density differences reached statistically significant levels between the normal corneal cells and the conjunctival epithelial cells on cornea (p<0.01). Goblet cells were visible throughout the conjunctivalised corneal epithelium in eight eyes. Several IVCM features could be correlated with histology in six of our patients. Conclusions A number of features were demonstrated by laser IVCM in patients presenting clinically with LSCD. Some of these features were corroborated with features observed on histological examination of tissue samples.

Ex vivo confocal microscopy of human corneal nerves.

Aims To evaluate the distribution, morphometry and the postmortem changes of the central and peripheral human corneal nerves by exvivo laser-scanning confocal microscopy (EVCM). Methods 24 eyes from 14 cadavers were retrieved at different time intervals after death and examined by EVCM. Five regions were examined in each eye: central, superior, inferior, temporal and nasal. In each region, corneal nerve images were categorised according to their anatomical location in the cornea into sub-basal, stromal and limbal nerves. Five nerve parameters were measured: density, orientation, diameter, numbers and branching pattern. Results Exvivo confocal scanning of a motionless eye allows high quality imaging and tracking of corneal and limbal nerves. Stromal nerves from the sub-Bowmans plexus perforate the Bowmans zone and terminate in bulb-like structures, from each of which a leash of sub-basal nerves arises. Following death, sub-basal nerve parameters showed significant changes. The density decreased from 9.23±4.48 to 0.45±0.07 mm/mm2, the diameter from 4.01±0.81 to 2.08±0.20 μm, the numbers from 8.3 to 1.0 and branching pattern from 39.38% to 0% (p<0.05) from day 1 to day 5 postmortem. Stromal and limbal nerves showed no significant changes in their density and diameter. Conclusions This study establishes a direct link between sub-basal nerves and the sub-Bowmans nerves via distinct terminal bulbs. Limbal nerves are the thickest, are seen in all quadrants and can be traced to the corneal centre. The sub-basal nerve plexus rapidly degenerates after death but stromal and limbal nerves survive during the first five days after death.

Corneal Intraepithelial Neoplasia: In Vivo Confocal Microscopic Study With Histopathologic Correlation

PURPOSE To ascertain in vivo confocal microscopic features of corneal/conjunctival intraepithelial neoplasia (CIN) and correlate these with histology of the same lesions. DESIGN Observational case series with evaluation of diagnostic technology. METHODS Four patients with unilateral CIN (3 men and 1 woman) were examined with the Heidelberg Retina Tomograph II (HRT II) Rostock Cornea Module (RCM) confocal microscope before, during, and after treatment. Corneal epithelial samples were taken by alcohol delamination technique in 2 patients, while impression cytology (IC) samples were obtained in the other 2 patients. Morphometric analysis of confocal and histologic images was carried out and the findings correlated. Four controls (all men, 2 with limbal stem cell deficiency, 1 with a limbal lesion, and 1 with diffuse keratoconjunctival proliferation) were similarly examined. Two of these had biopsy for histologic examination. Main outcome measures comprised the degree of correlation between histology and confocal microscopic features of CIN. RESULTS Dysplastic cellular changes were noticed on histopathology and correlated well with confocal microscopy, corresponding to the different corneal epithelial layers. Bright nucleoli within huge nuclei and ill-defined cell borders were a feature of the basal epithelium on histopathology and confocal microscopy. Subbasal corneal nerves were not visualized on confocal microscopy in areas affected by CIN. These features disappeared in response to treatment cycles as the basal epithelium reverted to its normal pattern, as seen by confocal microscopy. CONCLUSION Confocal microscopy findings highly correlate with histologic features in CIN. Confocal microscopic features of CIN as defined in this study will enable a reliable diagnosis in a noninvasive manner. Confocal microscopy will also allow real-time monitoring of the condition during treatment.

Histologic Features of Transplanted Amniotic Membrane: Implications for Corneal Wound Healing

PURPOSE To evaluate the histologic changes occurring in the transplanted amniotic membrane in human eyes. DESIGN Observational consecutive case series. PARTICIPANTS Seven consecutive patients who underwent amniotic membrane transplantation (AMT) for bullous keratopathy and subsequently had a penetrating keratoplasty (PK). METHODS Corneal buttons obtained at PK were examined by light and electron microscopy and by immunohistology with antibodies against CD34 (keratocytes), alpha smooth muscle actin and vimentin (myofibroblasts and fibroblasts respectively). Time from AMT to PK ranged from 2 to 32 months. MAIN OUTCOME MEASURES Immunophenotypic characteristics of cells populating transplanted amniotic stroma. RESULTS Amniotic tissue was covered with stratified corneal epithelium with well-defined desmosomes and hemidesmosomes. Transformed corneal stroma-derived cells (CSDCs) could be seen migrating from the anterior stroma, through breaks in the Bowmans zone, into connective tissue of the amniotic membrane. Immunohistology showed that the cells populating amniotic stroma were CD34 negative but positive for vimentin and alpha smooth muscle actin. In 2 samples in which corneal transplants were performed approximately 1 year or more after AMT, some cells in the amniotic stroma showed CD34+ staining. Features of increased metabolic activity and formation of new collagen were seen on electron microscopy. In 2 cases, epithelial cell nests were seen in the amniotic stroma. CONCLUSIONS The amniotic basement membrane facilitates epithelial cell migration and adhesion. The amniotic stroma supports CSDCs and epithelial cells. Repopulation of the amniotic stroma by CSDCs migrating through breaks in Bowmans zone integrates the amnion with corneal tissue and allows for rebuilding of corneal stroma. Over time, some CSDCs may revert to the resting keratocyte immunophenotype.

Corneal nerve aberrations in bullous keratopathy.

PURPOSE To study the corneal nerves in patients with chronic bullous keratopathy. DESIGN Prospective observational case series with histologic evaluation. METHODS We studied 25 eyes of 25 bullous keratopathy patients of different etiologies (17 female, 8 male; mean age, 76.3 years) as well as 6 eyes of 6 normal control subjects (5 male, 1 female; mean age, 38 years). All subjects were scanned by laser scanning confocal microscope. Five corneal buttons obtained following penetrating keratoplasty from 5 of the above patients and 6 normal control corneal buttons were stained as whole mounts with acetylcholinesterase (AChE) method for corneal nerve demonstration and scanned in multiple layers with digital pathology scanning microscope. RESULTS The density, branching pattern, and diameter of sub-basal nerves were significantly lower in corneas with bullous keratopathy compared with normal corneas (density: 4.42 ± 1.91 mm/mm(2) vs 20.05 ± 4.24 mm/mm(2); branching pattern: 36.02% ± 26.57% vs 70.79% ± 10.53%; diameter: 3.07 ± 0.64 μm vs 4.57 ± 1.12 μm). Aberrations such as localized thickenings or excrescences, abnormal twisting, coiling, and looping of the (mid) stromal nerves were observed in the study group both by in vivo confocal microscopy and on histology. CONCLUSIONS Striking alterations in corneal innervation are present in corneas with bullous keratopathy that are unrelated to any specific etiology of bullous keratopathy. This study provides histologic confirmation of novel in vivo confocal microscopy findings related to corneal nerves in bullous keratopathy.

In vivo confocal microscopy in the diagnosis and management of acanthamoeba keratitis showing new cystic forms

Acanthamoeba keratitis (AK) is a painful potentially blinding corneal infection that has been increasingly reported in association with soft contact lens wear. Pain out of proportion to signs is noted when there is associated nerve involvement but epithelial AK might not present with severe pain. We present two cases in whom the decision to treat for AK was based on in vivo confocal microscopy (IVCM) findings, with favourable outcomes. Novel IVCM presentations of cysts as ‘signet rings’ and ‘bright spots’ in addition to the classical ‘double wall’ images, were noted. In both cases, acanthamoeba were confirmed on culture as well. IVCM can provide early evidence of acanthameba infection. Treatment, when initiated while the organism is largely confined to the epithelium as was carried out in these two patients, can result in healing with minimal scarring. A 24-year-old female contact lens wearer presented with a 1-mm diameter paracentral stromal infiltrate (Fig. 1a) with no overlying ulcer, in her left eye. Her vision was 20/20. Routine IVCM examination with HRT II Rostock Cornea Module (Heidelberg Engineering,

Rings around Cones

A 65-year-old Caucasian male was referred for suspected keratoconus with Fleischer ring in both eyes. He had worn hard contact lenses since 1975 and recently changed to rigid gas permeable lens due to intolerance towards hard lens. His family history revealed that his son was diagnosed as having keratoconus. His best contact lens corrected visual acuity was 6/9 and 6/6 in the right and left eye, respectively. Slit-lamp examination revealed paracentral thinning, Vogt striae …

Localized conjunctival extra-nodal marginal zone B cell lymphoma with presumed paraproteinic crystalline keratopathy

Crystalline corneal deposits have been well reported in individual cases of lymphoproliferative disorders associated with hyper-gammaglobulinemia, hence called ‘Crystalline Paraproteinemic Keratopathy’. This is the first report of corneal deposits in a case of localised conjunctival B-cell Lymphoma without paraproteinaemia/hyper-gammaglobulinemia, hence called ‘Presumed Paraproteinic Crystalline Keratopathy’.