Differentiation-dependent expression of alpha-2,3-sialyltransferase in rabbit corneal epithelium.

PURPOSE: Lectin studies have shown that in the rabbit corneal epithelium, alpha-2,3 sialylation of O-linked glycans differentiates limbal and corneal epithelial cell phenotypes. Because sialic acid can be regulated at the level of the expression of sialyltransferases (STs), the purpose of the present study was to analyze the expression of alpha-2,3STs in this tissue. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used to generate ST cDNA from total rabbit corneal epithelium RNA using primers selected from the sequences of three previously cloned STs capable of catalyzing the transfer of sialic acid to O-linked oligosaccharides, human placental Galbeta-1,3GalNAc-Galbeta-1,4GluNAcalpha-2,3ST (STZ), and mouse brain Galbeta-1,3GalNAcalpha-2,3ST types I and II (ST3Gal I and ST3Gal II). Tissue distribution of mRNA was assayed by fluorescent in situ hybridization. A synthetic peptide whose sequence was deduced from a cloned cDNA fragment was synthesized and used to prepare an anti-ST goat antiserum. The molecular weights of immunodetectable polypeptides and their distribution in cryostat sections of the limbocorneal area were investigated by western blot analysis and indirect immunofluorescence, respectively. RESULTS: RT-PCR yielded cDNA of expected basepair length for STZ and ST3(Gal II. The rabbit STZ cDNA was 86% identical with its human equivalent. Its mRNA was confined to the cornea, mainly in basal epithelial cells, and was not expressed in the limbus. Western blot analysis identified a band at 37 kDa whose binding was abolished by preincubation of the antiserum with the immunization peptide. Immunohistologic analysis revealed the presence of immunoreactive epitopes in all basal cells of the cornea but not in the limbus. CONCLUSIONS: STZ mRNA and the enzyme itself are expressed in the basal layer of the corneal epithelium but are absent in the limbus. This enzyme's de novo expression seems thus responsible for the differential expression of alpha-2,3 sialylation along the limbocorneal differentiation axes. At least one more alpha-2,3ST is also present in the epithelium.

High-resolution ultrasound biomicroscopy of the pars plana and peripheral retina.

OBJECTIVE: This study aimed to evaluate the ability and role of ultrasound biomicroscopy in imaging the peripheral retina, pars plana, and anterior choroid. DESIGN: The study design was a case series. PARTICIPANTS: Seventeen eyes of 17 patients with a variety of clinical diagnoses involving the anterior portion of the posterior segment were studied. INTERVENTION: High-frequency (50 MHz), high-resolution (50 microns) ultrasound biomicroscopy was performed. RESULTS: Ultrasound biomicroscopy was capable of imaging the peripheral retina, pars plana, and anterior choroid. Images had features consistent with known histopathology. Retinoschisis consisted of one thin hyper-reflective echo and could be differentiated from a retinal detachment, which was thicker and formed a bilayered echo. A choroidal effusion could be identified as an echolucent space within the suprachoroidea, whereas a choroidal hemorrhage was moderately echodense. Inflammatory diseases, such as a sarcoid granuloma, pars planitis, and Harada's disease, were characterized by different forms of uveal thickening. A ciliochoroidal nevus was internally hyporeflective and could be measured accurately and localized. CONCLUSIONS: Imaging of the peripheral retina, pars plana, and anterior choroid is possible with ultrasound biomicroscopy and may aid in the diagnosis and management of pathology involving this region.

Peter's anomaly: diagnosis by ultrasound biomicroscopy.

Peter's anomaly is a congenital corneal disorder characterized by a central leukoma and adhesions at the periphery of the corneal opacity. A 35-year-old man presented for clinical evaluation of suspected sclerocornea. High-resolution ultrasound biomicroscopy revealed iridocorneal adhesions throughout the anterior segment, a shallow anterior chamber, and abnormal hyper-reflectivity along the posterior corneal surface. Through ultrasound biomicroscopy, characteristics of Peter's anomaly were recognized, and a diagnosis was established. This case illustrates how ultrasound biomicroscopy aids in the clinical differentiation between Peter's anomaly and other causes of congenital corneal opacification.

Ultrasound biomicroscopy in anterior ocular trauma.

BACKGROUND AND OBJECTIVE: The authors investigated the role of ultrasound biomicroscopy after ocular trauma. PATIENTS AND METHODS: Ultrasound biomicroscopy was performed in six eyes of six patients at the New York Eye and Ear Infirmary after a variety of traumatic ocular injuries. RESULTS: Eyes with angle recession, iridodialysis, cyclodialysis, hyphema, an intraocular foreign body, scleral laceration, and subluxed crystalline lens were imaged without complication. Ultrasound biomicroscopy aided in the diagnosis when visualization was limited by media opacities or distorted anterior segment anatomy. CONCLUSION: Ultrasound biomicroscopy is a safe and effective adjunctive tool for the clinical assessment and management of ocular trauma, especially when visualization is limited and multiple traumatic injuries are involved.

Ciliary body enlargement and cyst formation in uveitis.

BACKGROUND: Acute anterior uveitis has diverse causes and systemic associations. Inflammation is predominantly localised to the iris and pars plicata. Little is known about the in vivo effects of uveitis on ciliary body anatomy. METHODS: Bilateral, high frequency, high resolution, ultrasound biomicroscopy was performed on consecutive patients with unilateral anterior uveitis to evaluate ciliary body anatomy. Imaging was repeated when possible during the clinical course. The cross sectional area of the anterior ciliary body was measured using image processing and analysis software. Measurements from the uveitic eyes were compared with the fellow eyes and the effect of treatment was evaluated. RESULTS: Fourteen patients were enrolled. Ultrasound biomicroscopy demonstrated a larger ciliary body cross sectional area in the uveitic eyes compared with the fellow, clinically uninvolved eyes (2.45 (SD 0.48) mm2 versus 1.55 (SD 0.15) mm2, (p = 0.0000; paired t test)). A ciliochoroidal effusion was present in one uveitic eye. Epithelial cysts were imaged bilaterally in four uveitic patients (29%) and unilaterally in unaffected eyes of two uveitic patients. Ciliary body cross sectional area decreased following steroid therapy (p = 0.0001; paired t test). New cysts were noted in three uveitic eyes during the follow up period and in none of the fellow, unaffected eyes. CONCLUSION: Ultrasound biomicroscopy offers a new approach to the evaluation of anterior uveitis. The response to treatment can be evaluated objectively and therapeutic efficacy can be more easily assessed. It has the potential to help elucidate the pathophysiology and anatomical changes of this heterogeneous group of disorders.

Increase in iris-lens contact after laser iridotomy for pupillary block angle closure.

PURPOSE: To quantitate changes in anterior ocular segment anatomy after laser iridotomy for pupillary block angle closure. METHODS: We prospectively performed ultrasound biomicroscopy and A-scan biometry in 13 eyes of 13 consecutive untreated patients with relative pupillary block and appositional angle closure, without peripheral anterior synechiae on indentation gonioscopy. A radial, perpendicular image in the horizontal temporal meridian was obtained with ultrasound biomicroscopy before and one week after laser iridotomy in each eye. RESULTS: Mean age of the 13 patients was 69.3 +/- 1.8 (S.E.) years, mean refractive error was +1.37 +/- 0.39 diopters, and mean axial length was 22.54 +/- 0.20 mm. In 13 eyes, before and after laser iridotomy measurements of angle-opening distance (0.11 +/- 0.02 vs. 0.18 +/- 0.02 mm) (P = .0004; paired t test), angle aperture (8.3 +/- 1.3 vs 18.6 +/- 2.8 degrees) (P = .0003) and iris-lens contact distance (0.58 +/- 0.06 vs 1.18 +/- 0.14 mm) (P = .0003) were greater postoperatively, but anterior chamber depth was unchanged (P = .7). CONCLUSIONS: Flattening of the iris after laser iridotomy for pupillary block causes an increase in iris-lens contact. The change in angle configuration after iridotomy results more from an alteration in aqueous pressure gradients across the iris rather than from posterior lens movement.

Reduced trabecular meshwork height in juvenile primary open-angle glaucoma.

OBJECTIVE: To compare trabecular meshwork height in a series of patients with juvenile primary open-angle glaucoma (JPOAG) with that in normal control patients. METHODS: Ultrasound biomicroscopy and A-scan biometry were performed on 16 eyes with JPOAG and 24 normal eyes. A radial, perpendicular image in the horizontal temporal meridian detailing the line of Schwalbe, scleral spur, and angle anatomy was obtained for each eye by a single examiner. Trabecular meshwork height was defined as the distance from the scleral spur to the Schwalbe line. RESULTS: Mean patient age (P = .85, t test), refractive error (P = .68), sex distribution (P = .26, Fisher exact test) and axial length (P = .39) were similar between the groups. Mean +/- SE trabecular meshwork heights were 0.36 +/- 0.03 mm (range, 0.19-0.53 mm) for JPOAG and 0.58 +/- 0.02 mm (range, 0.40-0.80 mm) for controls (P < .001). Eyes with greater axial length tended to have larger trabecular meshworks in both groups (P = .012, multivariate regression). A trabecular meshwork height-axial length ratio of 0.021 or less was associated with a significantly increased risk for JPOAG being present (odds ratio, 57; 95% confidence interval, 6.0-541). CONCLUSIONS: The trabecular meshwork is smaller in eyes with JPOAG compared with that in normal eyes. This finding suggests a structural abnormality that may underlie the reduced outflow.

Risk factors for ciliochoroidal effusion after panretinal photocoagulation.

PURPOSE: To determine the incidence, duration, and risk factors for ciliochoroidal effusion after panretinal photocoagulation. METHODS: Thirty-nine consecutive patients with diabetic retinopathy underwent ultrasound biomicroscopy of both eyes to image the ciliochoroidal space immediately before and 1 day after unilateral argon-green panretinal photocoagulation. Imaging was repeated on days 3, 7, and 14 in patients in whom ciliochoroidal effusion developed. RESULTS: Low-lying ciliochoroidal effusions were imaged in 23 (59%) of 39 eyes. Of 23 eyes, effusions resolved in 6 (26%), 12 (52%), and 5 (22%) eyes by 3, 7, and 14 days respectively. The number of laser applications (P = 0.02), shorter axial length (P = 0.01), and percentage of retinal surface area treated (P = 0.02) were associated with systemic hypertension, location of treatment, previous panretinal photocoagulation of cataract surgery, retinal surface area treated, and mean blood pressure before photocoagulation were not associated with effusion. All fellow, untreated eyes remained effusion-free. CONCLUSION: Ciliochoroidal effusion develops commonly after panretinal photocoagulation. Limiting the number of laser applications and the percentage of retinal surface area treated reduces the likelihood of this complication. Eyes with shorter axial lengths are at higher risk

Ultrasound biomicroscopic features of iris retraction syndrome.

BACKGROUND AND OBJECTIVES: To examine anatomic relationships of anterior and posterior chamber structures in iris retraction syndrome using ultrasound biomicroscopy. PATIENTS AND METHODS: Four eyes of four patients with iris retraction syndrome were imaged using high-frequency, high-resolution, anterior segment ultrasound biomicroscopy. In two patients, scans were obtained before and after medical therapy. RESULTS: Three patients presented with iris retraction configuration and one with iris bombe. In the latter case, iris bombe converted to iris retraction and back to iris bombe with the administration and later withdrawal of aqueous suppressants. Ciliochoroidal effusion was present in all eyes. CONCLUSIONS: Ciliochoroidal effusion is a constant feature of iris retraction syndrome. The hypotony associated with this disorder may result in part from aqueous hyposecretion related to ciliary body detachment. Ultrasound biomicroscopy is a useful aid in the diagnosis and follow-up of eyes with iris retraction syndrome.

Location of the iris insertion in pigment dispersion syndrome.

PURPOSE: To evaluate the position of the iris insertion into the ciliary body in persons with pigment dispersion syndrome (PDS) and control subjects. METHODS: Ultrasound biomicroscopy was performed on 19 eyes with PDS and on 21 eyes of control subjects. A radial, perpendicular image in the temporal meridian detailing Schwalbe line (SL), scleral spur (SS), and iris root insertion (IR) was obtained for each eye by a single examiner. The distances between these structures then was measured. RESULTS: There were no differences between the groups in refractive error (mean +/- standard error, -2.8 +/- 0.7 diopters for PDS eyes versus -2.2 +/- 0.6 for control subjects) (P=0.46), sex distribution (P=0.49), and trabecular meshwork height (SL to SS) (0.63 +/- 0.03 mm [PDS eyes] versus 0.59 +/- 0.03 [control eyes]; P = 0.24). The SS-to-IR distance was significantly greater in PDS eyes (0.04 +/- 0.04 mm) than in control eyes (0.28 +/- 0.04 mm) (P=0.01) as was the overall distance from SL to IR (0.98 +/- 0.04 mm versus +/- 0.04 mm) (P = 0.003). CONCLUSION: The insertion of the iris into the ciliary body is more posterior in PDS eyes than in control eyes. This anatomic variation places the iris pigment epithelium proximal to the zonular apparatus and may increase the likelihood of iridozonular contact and zonular pigment dispersion.

Imaging congenital optic disc pits and associated maculopathy using optical coherence tomography.

OBJECTIVE: To elucidate the anatomy of congenital optic disc pits with and without maculopathy using optical coherence tomography. SETTING: All patient were examined, photographed, and scanned at the New York Eye and Ear Infirmary. PATIENTS: Ten eyes of eight consecutive patients with congenital optic disc pits were studied. Three eyes had associated serous macular detachment (group 1), four had evidence of resolved detachment (group 2), and three had no clinical macular pathologic lesion (group 3). METHODS: Optical coherence tomography, a new, noninvasive, noncontact, imaging technology capable of producing cross-sectional images of the retina in vivo with high resolution ( < 17 microns) was used to obtain multiple cross-sectional images of the pit, peripapillary retina, and macula. Ophthalmologic examination and standard fundus photography were performed on all eyes. Fluorescein angiography was performed in eyes that had associated macular detachment. RESULTS: Communication between a schisis cavity or subretinal space and the optic nerve pit was imaged in all eyes in group 1. No such communication could be identified in groups 2 and 3. Cystic degeneration and schisis were imaged in the peripapillary retina, macula, or both in all eyes of groups 1 and 2 and in one patient in group 3. A direct communication between the subretinal space and vitreous cavity could not be identified in any eye. CONCLUSIONS: Schisis formation plays an integral role in the development of serous retinal detachment in the presence of congenital optic disc pits. Our findings are consistent with the theory that the optic disc pit acts as a conduit for fluid flow between the schisis cavity or subretinal space and the subarachnoid space.

Na(+-) Cl(-)- and HCO3(-)-dependent base uptake in the ciliary body pigment pigment epithelium.

Segments of whole ciliary body dissected from Dutch belted rabbits were incubated for 60 min at 36 degrees C in a 30 microM Ca2+ Ringer's. The inner limiting membrane with its adherent non-pigmented epithelium then was mechanically removed from the surface. The newly-exposed viable layer of pigmented cells was then loaded with the fluorescent probe 2'-7'-bis (carboxymethyl)-5(6) carboxyfluorescein by incubating the segments for 45 min at RT with the cell permeable acetoxymethoxy form of the dye. These loaded tissues were perfused in a flow-through chamber, mounted on the heated stage of a microscope equipped for quantitative epifluorescence, and the intracellular pH (pHi) of small groups of cells was derived from the ratio of emission intensities generated by excitations at 490 and 440 nm, respectively. In N[2-hydroxyethyl] piperazine-N"-[2 ethane sulfonic acid](Hepes)-buffered Ringer's the intracellular pH was 7.23 +/- 0.21 (+/- S.D., n = 20). Replacement of 28 mM Hepes by 28 mM HCO3-/5% CO2 led to a 0.14 +/- 0.04 increase in pHi. This increase required the presence of Na+ and Cl- and was inhibited by 0.2 mM diisothiocyanatostilbene-2-2'-disulfonic acid. These observations as well as characteristic pHi, responses to the removal or introduction of Na+ or Cl- indicated the presence in the pigmented cells of a Na(+)- and Cl(-)-dependent HCO3- transporter responsible for base uptake.

Separation of the rabbit ciliary body epithelial layers in viable form: identification of differences in bicarbonate transport.

Sections of whole ciliary (CB) dissected from Dutch belted rabbits were incubated for 2 hr at 36 degrees C in a 30 microM Ca2+ Ringer's. This incubation resulted in the spontaneous dissociation of the two cell layers comprising this epithelium, each remaining firmly cohesive with its own basement membrane. The inner limiting membrane with its adherent non-pigmented epithelium (NPE) was then mechanically removed from the surface exposing the apical surface of the pigmented epithelium (PE). Ultrastructural examination revealed no noxious effects in most cells although gross morphological changes in the NPE cells were noted. The newly separated layers were loaded with the cell-permeable acetoxymethyl ester form of the fluorescent probe BCECF. Most cells of both layers acquired stable BCECF fluorescence indicating viability. To achieve a preliminary evaluation of differences in PE and NPE bicarbonate transport, dye-loaded tissues were perfused in a flow-through chamber which was mounted on a microscope equipped for quantitative epifluorescence. The intracellular pH (pHi) of groups of cells (5-10) was derived from the ratio of emission intensities generated by excitations at 490 and 440 nm. In Hepes-buffered Ringer's the pHis for the PE and NPE were 7.20 +/- 0.10 and 7.33 +/- 0.14 (+/- S.D., n = 6), respectively. Replacement of 28 mM Hepes by 28 mM HCO3-/5% CO2 led to a 0.13 pHi increase in the PE and a decrease of 0.27 U in the NPE. The pHi responses of the two cell layers to removal and/or reintroduction of Na+ and/or Cl- were also highly dissimilar.(ABSTRACT TRUNCATED AT 250 WORDS)