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Scanning electron microscopy of intumescent white cataract

Poster Details

First Author: M.Hawlina SLOVENIA

Co Author(s):    S. Andjelic   K. Dra┼ílar   A. Hvala        

Abstract Details



Purpose:

The lens capsule and lens epithelium cell complex represents a primary site of barrier and active transport and plays a crucial role in maintaining the levels of electrolytes and water in the lens that are necessary for preserving of lens transparency. We have previously studied white intumescent cataracts with transmission electron microscopy performed at Institute of Pathology3 (Hawlina M et al, Acta Ophthalmologica 2011) and we now extended the study with scanning electron microscopy (SEM). Intumescent white cataract is defined as a swelling of the lens because of fluid absorption due to LEC dysfunction and related protein changes in Na - K pump of LECs. Its dysfunction results in inward osmotic pressure and LECs swelling, which does not occur in nuclear cataracts. The purpose was to study the disturbed morphology of the anterior LECs and the structure of the anterior lens capsule (aLC) of intumescent white cataract in comparison with nuclear cataract in order to prove possible structural reasons for the intumescent white cataract.

Setting:

The aLCs were obtained by capsulorhexis from routine uneventful cataract surgery performed at the Eye Hospital, University Medical Centre (UMC), Ljubljana, Slovenia. All tissue collection complied with the Guidelines of the Helsinki Declaration and was approved by the National Medical Ethics Committee of Slovenia and all patients signed an informed consent form before the operation. After the surgery, the aLCs were prepared for Scanning electron microscopy (SEM) performed at Biotechnical Faculty2.

Methods:

Anterior LCs were obtained freshly after cataract surgery and washing step was applied to the specimens with sodium cacodylate buffer 0.1M, pH 7.2. Then the specimens were double fixed: first, by 1% glutaraldehyde and 0.5 % formaldehyde in 0.1M cacodylate buffer, pH 7.2 for 2 hours (25% glutaraldehyde EM grade; SPI and formalin were obtained from paraformaldehyde, Sigma); second, by 1% OsO4 in cacodylate buffer for 45 min. Dehydration of the LC tissue was performed in an ethanol cascade. For drying of specimens, critical point drying (CPD, Balzers CPD 030 Critical Point Dryer) procedure with CO2 was applied. Dried specimens were glued by carbon adhesive discs to specimen stubs, then Pt sputtered (Bal-Tec SCD 050 Sputter Coater) and examined in field emission scanning electron microscope (FESEM, 7500F, JEOL).

Results:

We observed by SEM that in the aLC obtained from patients with intumescent white cataract, one significant part of the fixed aLC tissue had a LEC monolayer with the dent/cleft surrounding the groups of LECs. This was not observed on the aLCs obtained from the patients with nuclear cataract. In aLC with intumescent white cataract, swelling was pronounced and rounded extrusions/bulges and the spheres were observed. The extrusions of the aLECs were observed on the swollen aLECs, on their apical side, opposite from the basal lamina. Extrusions of different structures could be followed as steps toward the sphere formation. The spheres were observed on the top of the anterior lens epithelium, on its apical side towards fibre cell layer. The structures of the aLC of intumescent white cataract similar to Morgagnian globules were also observed.

Conclusions:

We show by SEM that the aLC LECs of intumescent white cataract have the pronounced structural features not observed in nuclear cataract suggesting that the structure of aLC LECs plays a role in water accumulation in the lens in intumescent white cataract. We also suggest that aLECs by extrusions produce spheres/globules that can form the structures of degenerated material on aLC similar to Morgagnian globules, which are known to be proteinaceous globules produced from the degeneration of optic lens fibers. Intumescent white cataract, known as a mature cataract that progresses; with the lens becoming swollen from the osmotic effect of degenerated lens protein, may be a step toward the mature cortical cataract which hallmark is globular degeneration. FINANCIAL INTEREST: NONE

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