Biomedical subjects

Barbara Kiss

Publications and source records attributed to Barbara Kiss.

At least 19 recordsLinked to original sources

PubMed2006

Influence of severity of nuclear cataract on optical biometry.

PURPOSE: To compare preoperative and postoperative measurements of the axial length (AL) performed with the IOLMaster (Carl Zeiss Meditec) to evaluate the effect of nuclear cataract on the optical biometry. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: In 245 consecutive eyes of 162 patients scheduled for cataract surgery, type and severity of cataract was evaluated using the Lens Opacities Classification System III. Preoperative and postoperative axial length measurements were performed with the IOLMaster. The postoperative readings of AL were corrected for the IOL optic material implanted. RESULTS: The preoperative AL measurements were 0.07 mm +/- 0.05 (SD) (range -0.18 to 0.11 mm) longer than the postoperative measurements (P<.001). These differences in AL were only weakly correlated (r = -0.28, P = .01) with the nuclear cataract grade, mean 3.5 +/- 0.9. CONCLUSION: In this study, AL measurements with optical biometry using the IOLMaster were not influenced by the severity of nuclear cataract to a clinically relevant degree. Furthermore, it was found that AL in the phakic eye was overestimated by about 0.07 mm because of a slightly too low value of the group refractive index used for the crystalline lens.

Adult↗

PubMed2005

Long-term efficacy of adding a sharp posterior optic edge to a three-piece silicone intraocular lens on capsule opacification: five-year results of a randomized study.

PURPOSE: To compare the intensity of capsule opacification with the sharp and the round optic edge variant of an open-loop hydrophobic silicone intraocular lens (IOL). DESIGN: Randomized, controlled, double-blind clinical trial with intraindividual comparison. METHODS: Fifty-one patients with bilateral age-related cataract were included (102 eyes). Each patient had had cataract surgery in both eyes and received a Microsil IOL with a sharp optic edge design (model S) in one eye and a Microsil IOL with a round optic edge design (model R) in the fellow eye. Both IOLs had an identical haptic design (nonangulated polymethylmethacrylate) and silicone optic material. The patients were examined at the slit lamp, best-corrected visual acuity was assessed, and standardized high-resolution digital retroillumination images of the posterior capsule were taken 5 years after surgery. The intensity of regeneratory posterior capsule opacification (rPCO), fibrotic PCO (fPCO), and anterior capsule opacification (ACO) was assessed subjectively at the slit lamp, and of rPCO, objectively using automated image analysis software (AQUA). The need for an Nd:YAG laser capsulotomy (Nd:YAG-LCT) was noted. RESULTS: The mean AQUA PCO score was 1.2 for the model S and 2.4 for the model R lens (P = .001). The model S lens also led to less peripheral fPCO (P = .003). Concerning ACO, there was no significant difference between both IOL groups (P = .72). Whereas no capsulotomy was required with the model S, four cases (16%) had been performed in the model R group. CONCLUSION: Five years postoperatively, the sharp-edged silicone IOL showed less rPCO and fPCO than the round-edged IOL. However, regarding ACO, there was no significant difference between both IOL styles.

Aged↗

PubMed2005

Optical biometry of the anterior eye segment: interexaminer and intraexaminer reliability of ACMaster.

PURPOSE: To evaluate the interexaminer and intraexaminer reliability of corneal thickness, anterior chamber depth (ACD), and crystalline lens thickness measurements using a commercially available anterior segment optical biometry instrument (ACMaster, Carl Zeiss Meditec) based on partial coherence interferometry (PCI). SETTING: Medical University of Vienna, Vienna, Austria. METHODS: Interexaminer reliability and intraexaminer reliability were evaluated in 10 eyes of 10 young volunteers and 11 eyes of 11 cataract patients. The measurements of the interexaminer reliability were taken by 3 examiners. Corneal thickness, ACD, and lens thickness of the intraexaminer reliability were measured twice in all eyes by 1 examiner. To evaluate the effect of cycloplegia on the variability, the measurements were performed on 5 volunteers under cyclopentolate 1%. Measurements were performed using the prototype of the ACMaster based on PCI. RESULTS: The interexaminer/intraexaminer reliabilities were 99.9% for corneal thickness and ACD. The reliability of lens thickness could not be estimated because of a large number of missing values in the cataract patient group. The median interexaminer variability (SD) was 1.9 microm for corneal thickness, 7.5 microm for ACD, and 10.6 microm for lens thickness. The median intraexaminer variability (SD) was 1.6 microm for corneal thickness, 10.8 microm for ACD, and 8.7 microm for lens thickness. With cycloplegia, both the interexaminer variability and intraexaminer variability were smaller than without cycloplegia. CONCLUSIONS: Partial coherence interferometry measurements of anterior chamber distances (corneal thickness, ACD, lens thickness) using the prototype of ACMaster were highly reliable, allowing examiner-independent measurements. However, lens thickness measurements in cataract eyes were often difficult.

Adult↗

PubMed2005

Effects of moderate changes in intraocular pressure on ocular hemodynamics in patients with primary open-angle glaucoma and healthy controls.

PURPOSE: There is some indirect evidence for altered autoregulation in patients with glaucoma, but only a few studies have measured ocular blood flow directly during changes in ocular perfusion pressure. The present study was designed to compare pulsatile choroidal blood flow and optic nerve head (ONH) blood flow during moderate increases in intraocular pressure (IOP) in patients with primary open-angle glaucoma (POAG) and normal controls. DESIGN: Two nonrandomized studies comparing blood flow responses in glaucoma patients and controls in an open design. PARTICIPANTS AND CONTROLS: Sixteen patients with POAG glaucoma and 16 healthy gender-matched and age-matched controls were included in the choroidal blood flow experiments. The ONH blood flow experiment was performed in 14 POAG patients and 14 healthy gender-matched and age-matched controls. METHODS: In the first study, pulsatile choroidal blood flow was assessed by laser interferometric measurement of fundus pulsation amplitude (FPA). In the second study, ONH blood flow was measured using laser Doppler flowmetry. In both cohorts, the IOP was increased stepwise by 10 and 20 mmHg using a suction cup. MAIN OUTCOME MEASURES: Fundus pulsation amplitude and ONH blood flow. RESULTS: The baseline values of FPA and ONH blood flow were lower in glaucoma patients as compared with age-matched and gender-matched healthy controls. In patients with POAG, FPA decreased by -4.5+/-5.8% and -11.3+/-4.9% during elevation of IOP of 10 and 20 mmHg, respectively. These results were not different from the results in healthy controls, where FPA decreased by -5.1+/-3.4% and -12.2+/-4.9% at the 2 pressure levels (P = 0.23 between groups). Optic nerve head blood flow showed no changes during the increase of IOP of 10 and 20 mmHg in either of the 2 groups (glaucoma patients, +2.1+/-14.7% and -0.8+/-15.2%; healthy controls, +4.3+/-12.0% and +0.2+/-14.2%; P = 0.83 between groups). CONCLUSIONS: The present study does not provide evidence for altered autoregulation in patients with POAG during a moderate increase in IOP. However, these results do not necessarily contradict the concept of vascular dysregulation in glaucoma.

Aged↗

PubMed2005

Natural course of intraocular pressure after cataract surgery with sodium chondroitin sulfate 4%-sodium hyaluronate 3% (Viscoat).

PURPOSE: To investigate the natural course of intraocular pressure (IOP) and its peak after small-incision cataract surgery with chondroitin sulfate 4%-sodium hyaluronate 3% (Viscoat, Alcon Laboratories, Inc., Fort Worth, TX). DESIGN: Observational case series. PARTICIPANTS: This prospective study comprised 40 eyes of 40 consecutive cataract patients scheduled for small-incision cataract surgery. METHODS: Cataract surgery was performed with sodium chondroitin sulfate 4%-sodium hyaluronate 3% as the ophthalmic viscosurgical device, which was removed as completely as possible from the eye at the end of surgery. The IOP was measured preoperatively and 30 minutes; 1, 2, 3, 4, 6, 8, and 20 to 24 hours; and 1 week postoperatively. MAIN OUTCOME MEASURES: Postoperative IOP increase. RESULTS: The mean IOP increased significantly at all observation times during the first 20 to 24 hours, with a peak increase of 13.4+/-9.4 mmHg after 1 hour (P<0.05). In all, 28 eyes (70%) had an IOP spike to 30 mmHg or higher. Sixty-eight percent of these spikes occurred at 30 minutes as well as at 1 hour and 2 hours postoperatively. At 20 to 24 hours, no eye had an IOP spike to 30 mmHg or higher. CONCLUSIONS: Significant IOP increases were found during the first 24 hours, peaking at 1 hour after surgery. With a single postoperative IOP measurement, between 30 minutes and 2 hours after surgery, two thirds of these IOP spikes could be detected. To detect all IOP spikes, a second measurement between 4 and 6 hours after surgery would be necessary.

Aged↗

PubMed2004

Central corneal thickness measurements with partial coherence interferometry, ultrasound, and the Orbscan system.

OBJECTIVE: To compare the reliability of central corneal thickness measurements (CCT) obtained with partial coherence interferometry (PCI), ultrasound pachymetry, and the Orbscan system. DESIGN: Cross-sectional study. PARTICIPANTS: Twenty healthy subjects with CCT measurements in both eyes. METHODS: The CCT measurements were obtained with PCI, ultrasound pachymetry, and the Orbscan system. In each eye, 2 investigators performed 5 repeated measurements with each pachymetric device. Intraclass correlation coefficients (kappa) were calculated and mean CCT measurements were compared. MAIN OUTCOME MEASURES: The CCT measurements obtained with ultrasound pachymetry, the Orbscan system (Orbtek Inc., Salt Lake City, UT), and PCI. RESULTS: Mean CCT values measured with ultrasound pachymetry were significantly thicker than those measured with PCI (21.5 microm; P<0.001) or the Orbscan system (19.8 microm; P<0.001). The correlation coefficients for the intraobserver variability were 0.999 for PCI measurements, 0.983 for ultrasound pachymetry measurements, and 0.988 for Orbscan system measurements. The correlation coefficients for the interobserver variability were 0.998 for PCI measurements, 0.980 for ultrasound pachymetry measurements, and 0.988 for Orbscan system measurements. There was a slightly better consistency between ultrasound pachymetry and PCI (kappa = 0.96) than between the Orbscan system and PCI (kappa = 0.92) and between ultrasound pachymetry and the Orbscan system (kappa = 0.89). CONCLUSIONS: Partial coherence interferometry was the method with the least intraobserver or interobserver variability. Mean CCT as measured with ultrasound pachymetry was approximately 20 microm thicker than with the Orbscan system and PCI. However, corneal thickness measurements with ultrasound pachymetry and PCI were slightly more consistent than those of the Orbscan system and PCI. This slightly better consistency, however, may be important, especially in corneal refractive surgery.

Adult↗

PubMed2004

Effect of optic edge design and haptic angulation on postoperative intraocular lens position change.

PURPOSE: To assess the effect of optic edge design and optic-haptic angulation of open-loop intraocular lenses (IOLs) on postoperative axial movement and the final position of the optic by measuring the anterior chamber depth (ACD) during the first postoperative year using partial coherence interferometry (PCI). SETTING: Department of Ophthalmology, Vienna General Hospital, Institute of Medical Physics, University of Vienna, Vienna, Austria. METHODS: In study 1, a 3-piece silicone IOL with nonangulated modified C-loop haptics (MicroSil, Dr. Schmidt) was implanted in 78 eyes of 39 patients; patients were randomized to receive a round-edged optic IOL in 1 eye and a sharp-edged optic IOL in the other eye. The ACD was measured by PCI 1 day, 1 week, 3 months, and 1 year after surgery. In study 2, a foldable, 3-piece acrylic IOL with modified 10-degree angulated J-loop haptics (AcrySof MA60BM, Alcon) was implanted in 32 eyes of 32 patients. The ACD was measured by PCI 1 day, 1 week, and 3 months after surgery. RESULTS: In eyes with a nonangulated silicone IOL, there was a significant postoperative change in ACD with both sharp-edged and round-edged designs (P<.01). There was forward movement of both IOL designs in the first week, with no significant difference between the 2 models. From 1 week to 3 months, there was backward movement of IOLs of both designs, with the sharp-edged IOL moving a significantly greater amount (P<.001). From 3 months to 1 year, IOLs with both optic edge designs moved slightly backward. Sixty-six percent of angulated IOLs showed continuous but variable forward movement and 34%, backward movement. CONCLUSIONS: Optic edge design influenced postoperative axial optic movement and thus had an impact on the development of postoperative refraction (refractive shift, deviation from target refraction). The influence of optic-haptic angulation proved to be significantly greater and more variable than edge design.

Acrylic Resins↗

PubMed2003

Nitric oxide regulates retinal vascular tone in humans.

The purpose of the present study was to investigate the contribution of basal nitric oxide (NO) on retinal vascular tone in humans. In addition, we set out to elucidate the role of NO in flicker-induced retinal vasodilation in humans. Twelve healthy young subjects were studied in a three-way crossover design. Subjects received an intravenous infusion of either placebo or NG-monomethyl-L-arginine (L-NMMA; 3 or 6 mg/kg over 5 min), an inhibitor of NO synthase. Thereafter, diffuse luminance flicker was consecutively performed for 16, 32, and 64 s at a frequency of 8 Hz. The effect of L-NMMA on retinal arterial and venous diameter was assessed under resting conditions and during the hyperemic flicker response. Retinal vessel diameter was measured with a Zeiss retinal vessel analyzer. L-NMMA significantly reduced arterial diameter (3 mg/kg: -2%; 6 mg/kg: -4%, P < 0.001) and venous diameter (3 mg/kg: -5%; 6 mg/kg: -8%, P < 0.001). After placebo infusion, flicker induced a significant increase in retinal vessel diameter (P < 0.001). At a flicker duration of 64 s, arterial diameter increased by 4% and venous diameter increased by 3%. L-NMMA did not abolish these hyperemic responses but blunted venous vasodilation (P = 0.017) and arterial vasodilation (P = 0.02) in response to flicker stimulation. Our data indicate that NO contributes to basal retinal vascular tone in humans. In addition, NO appears to play a role in flicker-induced vasodilation of the human retinal vasculature.

Adult↗

PubMed2003

Short-term effect of dorzolamide hydrochloride on central corneal thickness in humans with cornea guttata.

OBJECTIVE: To investigate the short-term effect of dorzolamide hydrochloride, a topical carbonic anhydrase inhibitor, on central corneal thickness in patients with cornea guttata. DESIGN AND METHODS: In this randomized, placebo-controlled, double-masked, 3-drug crossover study, 20 patients with cornea guttata (mean endothelial cell count, 1321 cells/mm2) and 8 healthy control subjects (mean endothelial cell count, 2483 cells/mm2) were included. Study medications included 2% dorzolamide hydrochloride (Trusopt 2% eye drops; Merck & Co Inc, Whitehouse Station, NJ), 0.9% saline solution (saline placebo), and a solution identical to the carrier substance of dorzolamide in Trusopt (carrier placebo). The study drugs were applied 4 times per day for 1 day only. Central corneal thickness measurements were performed using partial coherence interferometry on every study day at baseline and after 24 hours of study medication treatment. MAIN OUTCOME MEASURES: Change in central corneal thickness. RESULTS: The mean thickening in central corneal thickness within 24 hours in eyes with cornea guttata treated with dorzolamide, saline placebo, and carrier placebo was 12.0 micro m (95% confidence interval [CI], 7.0-17.1 microm), 0.6 micro m (95% CI, -1.0 to 2.2 microm), and 1.3 micro m (95% CI, -0.1 to 2.6 microm), respectively. CONCLUSION: Application of dorzolamide for 1 day results in a slight but statistically significant thickening of central corneal thickness in patients with cornea guttata.

Administration, Topical↗

PubMed2003

Intraocular lens movement caused by ciliary muscle contraction.

PURPOSE: To investigate intraocular lens (IOL) movement, measured as a change in anterior chamber depth (ACD) caused by pilocarpine-induced ciliary muscle contraction. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: In this prospective study, the ACD was measured using high-precision, high-resolution, dual-beam partial coherence interferometry in 62 pseudophakic eyes of 55 patients under pilocarpine- and cyclopentolate-induced ciliary muscle contraction and relaxation. The following were studied: 2 models of a ring-haptic IOL (designed to accommodate), a plate-haptic IOL, and 3 types of 3-piece IOLs. Measurements were performed 3 months after surgery. RESULTS: The ring-haptic IOLs and plate-haptic IOL showed a forward movement (ring haptic 43A, -116 microm; ring haptic 43E, -222 microm; plate haptic -162 microm). The 3-piece IOLs showed no change in ACD except in 1 IOL type in which there was backward movement (156 microm). CONCLUSIONS: Pilocarpine-induced ciliary muscle contraction caused forward movement of ring- and plate-haptic IOLs that resulted in an estimated accommodative amplitude of less than 0.50 diopter in most cases. The accommodating ring-haptic IOLs did not perform better than the conventional plate-haptic IOL.

Accommodation, Ocular↗

PubMed2003

Corneal endothelial cell protection with a dispersive viscoelastic material and an irrigating solution during phacoemulsification: low-cost versus expensive combination.

PURPOSE: To evaluate the protective effect on corneal endothelial cells of a low-cost and an expensive combination of a dispersive viscoelastic material and an irrigating solution during phacoemulsification. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: This prospective randomized examiner- and patient-masked study comprised 90 eyes of 45 consecutive patients with age-related cataract in both eyes. For each patient, the first eye was randomly assigned to receive hydroxypropyl methylcellulose 2% (Ocucoat) and Ringer's solution (low-cost combination) or sodium chondroitin sulfate 4%-sodium hyaluronate 3% (Viscoat) and an enriched balanced salt solution (BSS Plus) (expensive combination) during phacoemulsification. The contralateral eye received the other treatment. Endothelial cell function was evaluated by measuring corneal thickness (CT) using partial coherence interferometry, morphology assessment, and endothelial cell counts. RESULTS: The acute postoperative increase in CT was +9.8 microm in the low-cost group and +10.9 microm in the expensive group; the difference between groups was not significant. After 1 month, the CT still differed significantly from baseline in the low-cost group. Three months after surgery, the CT had returned to baseline values in both groups. There was no significant between-group difference in endothelial cell counts or morphology. CONCLUSIONS: During phacoemulsification in a nonselected patient population, there was no difference in acute postoperative corneal edema and endothelial cell morphology after 3 months between a Viscoat and BSS Plus combination and an Ocucoat and Ringer's solution combination. Eyes receiving the expensive combination had marginally faster recovery of corneal swelling by 3 months. However, the cost of Viscoat and 500 mL BSS Plus is 5 times that of Ocucoat and Ringer's solution.

Aged↗

PubMed2003

After-cataract in adults with primary posterior capsulorhexis: comparison of hydrogel and silicone intraocular lenses with round edges after 2 years.

PURPOSE: To evaluate the potential of primary posterior continuous curvilinear capsulorhexis (PCCC) to prevent after-cataract 2 years after surgery and perform a bilateral comparison of 2 intraocular lens (IOL) materials, silicone and hydrogel. SETTING: Department of Ophthalmology, University of Vienna, Medical School, Vienna, Austria. METHODS: In this randomized patient- and examiner-masked study, 37 patients (74 eyes) with age-related cataract had bilateral small-incision cataract surgery with PCCC. Randomly, 1 eye received a hydrogel IOL and the contralateral eye, a silicone IOL. Both IOLs had open-loop haptics and a round-edged optic. Standardized digital retroillumination photographs were taken 1 day and 1, 6, 12, and 24 months after surgery to evaluate development of after-cataract on the anterior and posterior capsules by subjective grading. Opacification of the PCCC area was also objectively evaluated using new software. RESULTS: Twenty-nine patients (58 eyes) completed the 2-year follow-up. Partial closure with ongrowth at the edge of the PCCC was found in 55% in the hydrogel group and 28% in the silicone group. Total closure of the PCCC was observed in 3 eyes, 2 in the hydrogel group and 1 in the silicone group. CONCLUSION: Ongrowth onto the PCCC area was dependent on IOL material. Because of less ongrowth and more fibrotic after-cataract with silicone IOLs, the efficacy of the PCCC was higher in this group.

Aged↗

PubMed2003

Comparison of anterior chamber depth measurement methods in phakic and pseudophakic eyes.

PURPOSE: To compare anterior chamber depth (ACD) measurements in phakic and pseudophakic eyes using a slit-beam photographic technique (IOLMaster, Carl Zeiss Meditec AG) with those obtained with the laboratory prototype version of partial coherence interferometry (PCI) and with conventional applanation ultrasound in phakic eyes. SETTING: Department of Ophthalmology, Vienna General Hospital, Vienna University, Vienna, Austria. METHODS: Thirty-three ACDs of 28 patients with age-related cataract were measured preoperatively with a slit-beam photographic technique (IOLMaster) and the prototype version of PCI. In 24 eyes, the ACD was also assessed with applanation ultrasound. In addition, 34 ACDs of 18 pseudophakic patients in a different study population were examined postoperatively with the IOLMaster and PCI. RESULTS: The median ACD in the phakic eyes was 3.06 mm (range 1.93 to 3.90 mm) with the IOLMaster, 3.09 mm with PCI (range 1.49 to 4.06 mm), and 2.87 mm (range 2.18 to 3.33 mm) with applanation ultrasound. The precision was 0.005 mm for PCI and 0.015 mm for IOLMaster measurement. The median difference between the IOLMaster and PCI ACD biometry was 0.01 mm +/- 0.14 (SD) (range -0.44 to 0.17 mm) (P =.71). In pseudophakic eyes, the 2 methods showed a median difference of -0.22 mm (range -0.45 to 1.99 mm) (P >.1) and did not correlate (r = 0.21; P >.2). CONCLUSIONS: In phakic eyes, the difference between IOLMaster and PCI measurements was small and not statistically significant. In pseudophakic eyes, the difference was larger and the methods did not correlate.

Anterior Chamber↗

PubMed2003

Effect of a fixed dorzolamide-timolol combination on intraocular pressure after small-incision cataract surgery with Viscoat.

PURPOSE: To evaluate the effect of a fixed dorzolamide-timolol combination (Cosopt) on intraocular pressure (IOP) after small-incision cataract surgery with sodium chondroitin sulfate 4%-sodium hyaluronate 3% (Viscoat). SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: This prospective randomized study comprised 76 eyes of 38 patients scheduled for small-incision cataract surgery in both eyes. Patients were randomized to receive 1 drop of the fixed dorzolamide-timolol combination in 1 eye or no treatment (control) immediately after cataract surgery. The fellow eye received the other assigned treatment. Cataract surgery was performed with Viscoat in an identical fashion in both eyes. The IOP was measured preoperatively and 6 hours, 20 to 24 hours, and 1 week postoperatively. RESULTS: Six hours after surgery, the mean increase in IOP was significantly lower in the dorzolamide-timolol group than in the control group (4.3 mm Hg +/- 5.6 [SD] versus 8.4 +/- 6.1 mm Hg; P =.003). Two eyes in the dorzolamide-timolol group and 9 in the control group had IOP spikes of 30 mm Hg or higher (P =.022). Twenty to 24 hours after surgery, the mean IOP change was -2.6 +/- 3.3 mm Hg in the dorzolamide-timolol group and 1.5 +/- 3.2 mm Hg in the control group (P<.001). CONCLUSIONS: The fixed dorzolamide-timolol combination was effective in reducing IOP 6 hours and 20 to 24 hours after cataract surgery. However, it did not prevent Viscoat-induced IOP spikes of 30 mm Hg or higher.

Aged↗

PubMed2003

Influence of operator experience on the performance of ultrasound biometry compared to optical biometry before cataract surgery.

PURPOSE: To compare measurements performed with the IOLMaster (Carl Zeiss, Meditec AG) with those obtained by applanation ultrasound (US) and manual keratometry and to evaluate the effect of operator experience on US biometry. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: The axial length (696 eyes) and anterior chamber depth (ACD) (462 eyes) were measured in 377 patients with cataract using the IOLMaster and applanation US. To assess the effect of operator experience on the biometric results, the operators were divided into 2 groups: experienced and less experienced in performing US biometry. The difference in measurements between the methods and the variability of the difference were compared between the 2 groups. RESULTS: Applanation US measured axial length and ACD shorter than the IOLMaster; the mean numerical difference was 0.13 mm and 0.19 mm, respectively (P<.01). For axial length, the absolute difference was smaller with experienced operators than with less experienced operators (0.15 mm versus 0.22 mm) (P<.01). For ACD, experienced operators obtained a smaller difference between measurement techniques (0.21 mm versus 0.29 mm; P<.05). CONCLUSIONS: Experienced US operators had less difference and lower variability in the difference between applanation US and IOLMaster readings for axial length and ACD measurements. The noncontact optical method, which is essentially operator independent, gave significantly more reliable biometry before cataract surgery, especially in the case of less experienced operators.

Adult↗

PubMed2002

Retinal blood flow during hyperoxia in humans revisited: concerted results using different measurement techniques.

Retinal vasculature shows pronounced vasoconstriction in response to hyperoxia, which appears to be related to the constant oxygen demand of the retina. However, the exact amount of blood flow reduction and the exact time course of this phenomenon are still a matter of debate. We set out to investigate the retinal response to hyperoxia using innovative techniques for the assessment of retinal hemodynamics. In a total of 48 healthy volunteers we studied the effect of 100% O(2) breathing on retinal blood flow using two methods. Red blood cell movement in larger retinal veins was quantified with combined laser Doppler velocimetry and retinal vessel size measurement. Retinal white blood cell movement was quantified with the blue field entoptic technique. The time course of retinal vasoconstriction in response to hyperoxia was assessed by continuous vessel size determination using the Zeiss retinal vessel analyzer. The response to hyperoxia as measured with combined laser Doppler velocimetry and vessel size measurement was almost twice as high as that observed with the blue field technique. Vasoconstriction in response to 100% O(2) breathing occurred within the first 5 min and no counterregulatory or adaptive mechanisms were observed. Based on these results we hypothesize that hyperoxia-induced vasoconstriction differentially affects red and white blood cell movement in the human retina. This hypothesis is based on the complex interactions between red and white blood cells in microcirculation, which have been described in detail for other vascular beds.

Adult↗

PubMed2002

Biometry of cataractous eyes using partial coherence interferometry: clinical feasibility study of a commercial prototype I.

PURPOSE: To evaluate the clinical feasibility of the prototype version of a commercial partial coherence interferometry instrument (axial length measurement, ALM, Carl Zeiss Jena) for noninvasive, high-precision biometry in cataractous eyes. SETTING: Department of Ophthalmology, Vienna General Hospital, and Institute of Medical Physics, University of Vienna, Austria. METHODS: The preoperative axial length in 49 eyes of 37 cataract patients was measured with the commercial (ALM) and laboratory (PCI) prototypes of the partial coherence interferometry instrument, as well as with immersion ultrasound (IUS). RESULTS: Axial length measurements with the ALM and PCI did not differ significantly (P = .23). Both prototypes assessed longer axial lengths than the IUS technique (P < .0001; median 203 microm; range -476 to +635 microm). The precision of the axial length measurement was 18 microm, 28 microm, and 54 microm with the PCI, ALM, and IUS, respectively. CONCLUSIONS: Partial coherence tomography is a high-precision, high-resolution, noncontact biometric technique.The commercial PCI prototype is practical in clinical use, with improved comfort for patients, no need for anesthesia, and a reduced risk of infection. However, the difference between the PCI and IUS in axial length measurement must be considered when using the constants supplied by intraocular lens (IOL) manufacturers for IOL power calculations.

Adult↗

PubMed2002

Effect of an acrylic intraocular lens with a sharp posterior optic edge on posterior capsule opacification.

PURPOSE: To compare the posterior capsule opacification (PCO) inhibiting effect of the sharp posterior optic edge design of the Sensar OptiEdge AR40e intraocular lens (IOL) (Allergan Surgical) with that of the round-edged design of the Sensar AR40 IOL. Setting Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: This prospective randomized patient- and examiner-masked study comprised 106 eyes of 53 patients with bilateral age-related cataract. Each patient had cataract surgery in both eyes and received an AR40 IOL in 1 eye and an AR40e IOL in the other eye. Postoperative examinations were at 1 week, 2 and 6 months, and 1 year. Digital slitlamp and digital retroillumination images of each eye were taken. The amount of PCO was assessed subjectively at the slitlamp and objectively using automated image-analysis software. RESULTS: The AR40e group had significantly less regeneratory and fibrotic PCO 1 year after surgery. The mean automated image-analysis software PCO score (scale 0 to 10) was 2.19 in the AR40 group and 1.10 in the AR40e group (P <.001). The AR40e group had less peripheral fibrotic PCO. There was no significant difference in patient-reported edge glare between the 2 IOL groups. CONCLUSIONS: The sharp-edged design of the Sensar OptiEdge AR40e IOL led to significantly less PCO than the round-edged AR40 IOL 1 year postoperatively.

Acrylic Resins↗