Influence of viscoelastic substances used in cataract surgery on corneal metabolism and endothelial morphology: comparison of Healon and Viscoat.

PURPOSE: To evaluate the influence of cohesive and dispersive ophthalmic viscosurgical devices (OVDs) on endothelial morphology and corneal metabolism during cataract surgery. SETTING: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. METHODS: In this prospective randomized blind study, 50 eyes of 43 patients were randomized into 2 groups before surgery. Phacoemulsification with implantation of a posterior chamber intraocular lens was performed in all patients. In half the patients, sodium hyaluronate 1% (Healon) was used as the OVD and in the other half, sodium hyaluronate 3%-chondroitin sulfate 4% (Viscoat). Corneal metabolism was evaluated by fluorophotometric measurement of corneal autofluorescence. The corneal fluorescence values were corrected for interference by fluorescence of the ocular lens. Specular microscopy (Noncon Robo SP800, Canon) was used to evaluate the endothelial cell density, coefficient of variation, and percentage of hexagonal cells. Examinations were performed preoperatively and 3 days, 1 and 4 weeks, and 3 months postoperatively. RESULTS: There were no significant changes between preoperative and postoperative endothelial cell density measurements in either group (P =.1717). The percentage of hexagonal cells was similar (P =.3489); however, there was a slightly increasing tendency toward polymorphism in both groups. Corneal autofluorescence decreased 3 days after surgery, increased after 1 week, and decreased again subsequently in both groups. There was no significant difference in the influence on corneal metabolism between the 2 OVDs (P =.9899). CONCLUSIONS: There was no significant difference between Healon and Viscoat. Thus, this study did not confirm an advantage of either for endothelial protection of healthy corneas.

A new colour vision arrangement test to detect functional changes in diabetic macular oedema.

AIM: A study was undertaken to investigate the correlation between colour discrimination tests and the presence of macular oedema in patients with type I diabetes to find a sensitive diagnostic tool for the detection of early functional changes. METHODS: The study was performed in 39 type I diabetic patients, 10 with and 29 without macular oedema. The examination included biomicroscopy, fundus photography of the macula, videofluorescein angiography, the LogMAR visual acuity chart, Farnsworth-Lanthony desaturated D-15 test, and the new Mollon-Reffin "Minimalist" test for colour vision deficiencies version 6.0. RESULTS: A highly significant correlation was found between the tritan value of the Mollon test and the presence of clinically significant macular oedema (p<0.0015), with a high sensitivity (88.9%) and specificity (93.3%). The DD-15 test was not significant (p=0.345) and showed low sensitivity for the presence of macular oedema (36%). All variables concerning the grading of macular oedema showed a highly significant association with the tritan values of the Mollon test (p<0.0001). CONCLUSION: The results suggest that the Mollon-Reffin "Minimalist" test version 6.0 is the best colour discrimination test for detecting macular oedema, with higher specificity and sensitivity than the other methods used in the study.

Biomicroscopic measurement of the optic disc with a high-power positive lens.

PURPOSE: To compare the magnification properties of four different indirect double aspheric fundus examination lenses for clinical disc biometry. METHODS: Experimental study in a model eye. The relationship between the true size of a fundus object and its image was calculated for each fundus lens for an ametropic range between -12.5 and +12.6 D using a slit lamp biomicroscope with adjustable beam length. RESULTS: Equations for determining the correction factor p (degrees per millimeter) were calculated for each fundus lens. The factor can be used in calculations to determine true optic disc size. The total change in magnification of the system from myopia to hyperopia was -21.1% to +24.0% (60-D lens; Volk Opticals, Mentor, OH), -12.9% to +16.2% (Volk super 66 stereo fundus lens), -13.2% to +13.9% (Volk 78-D lens), and -13.3% to +14.0% (Volk super-field NC lens). When the fundus lens position was altered im relation to the model eye by +/-2 mm under myopic conditions, the change in magnification of the system was -4.3% to +5.7% (60-D lens), -4.6% to +6.1% (66 stereo fundus lens), -4.9% to +6.3% (78-D lens), and -5.9% to +7.8% (super-field NC lens). In the hyperopic condition the change was -2.7% to +3.6%, -3.4% to +4.5%, -3.6% to +4.8%, and -4.5% to +6.0%. CONCLUSIONS: The study has shown that the use of a single magnification correction value for each fundus lens may not be appropriate. These findings have important implications for the way in which calculations for determining the true optic disc size and other structures of the posterior pole are performed using indirect biomicroscopy.

Normalization of orbital arterial blood flow in non-ischemic central retinal vein occlusion after 6 months.

INTRODUCTION: Central retinal vein occlusion (CRVO) is a common vascular disorder and may lead to blindness. The aim of the study was to obtain information about the possible imbalance and recovery of orbital arterial blood flow in non-ischemic CRVO. METHODS: Vascular resistance (pulsatility index-PI) in the orbital arteries of 14 patients with non-ischemic CRVO was examined within 3 weeks after onset of CRVO and 6 months later. The control group consisted of 14 age- and sex-matched healthy control eyes. RESULTS: PI was increased in all orbital arteries of CRVO eyes measured within 3 weeks after the onset. Normal PI values were recorded in the same retrobulbar arteries, and re-measured 6 months later. DISCUSSION: There is an increase in vascular resistance in all orbital arteries at the onset of non-ischemic CRVO, followed by a recovery of vascular resistance to normal levels 6 months later. The increase at the onset may be caused by arterial vasospasm or by intraocular hemostasis affecting the afferent arteries.

[Results of fundus perimetry after resorbed premacular hemorrhages under the internal limiting membrane in 10 patients]. / Ergebnisse der Fundusperimetrie nach resorbierten prämakulären Sublimitansblutungen bei 10 Patienten.

BACKGROUND: During their acute phase, premacular hemorrhages under the internal limiting membrane induce an absolute scotoma. It is generally suspected that extravasal blood has a toxic effect on the neuroretina. The objective of this study is to investigate whether one can indeed detect sensoric defects after resorbed hemorrhages under the internal limiting membrane. MATERIALS AND METHODS: Our patient group consisted of 10 patients with resorbed premacular hemorrhages, which had been caused by either Vasalva-Manouver or arterial macroaneurysms. In order to avoid visual field defects due to other causes, patients with diabetes, retinal vein occlusion and glaucoma were excluded from this study. The investigation was carried out with the Scotometry Programme Vers. 2.01 of the Rodenstock Scanning Laser Ophthalmoscope. Furthermore, fundus photographs were taken. RESULTS: Under condition of no pre-existing retinal pathologies, no scotomas could be revealed at the site of the preretinal hemorrhage after full resorption. Relative or absolute scotomas could only be found in cases of pre-existing epiretinal gliosis, pigmentepitheliumdefect, persistent subretinal hemorrhages or scars. CONCLUSION: Since no sensoric defects of the retinal receptors could be detected, the hypothesis of the extravasal blood having a direct toxic effect on the neuroretina, could not be confirmed in this patient group.