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Biomedical subjects

Mana Tehrani

Publications and source records attributed to Mana Tehrani.

24 records · Page 2Linked to original sources
PubMed2003

[Cost effectiveness evaluation of cataract patient care in respect of monofocal intraocular lenses from the perspective of German statutory health insurance].

BACKGROUND: Data on the cost effectiveness of cataract surgery with respect to the German statutory health insurance system are hardly available. Hence the increase in visual acuity as primary efficacy endpoint, order of posterior capsule opacification as primary complication endpoint and direct cost for supplementation with monofocal intraocular lenses have been assessed via meta-analyses to evaluate the procedure's cost effectiveness from the perspective of the German statutory health insurance system. MATERIAL AND METHODS: Using the medical internet database MEDLINE two meta-analyses on publications between 1995 and 2002 were carried out, one estimating the gained increase in visual acuity, the second to estimate the frequency of posterior capsule opacification 5 years after implantation of a monofocal lens. To estimate the direct cost of German health insurance current reimbursement rates were used. The primary objective of this investigation was the individual incremental cost effectiveness ratio (ICER) linking the direct cost with the cataract surgery-associated increase in visual acuity. RESULTS: 51 studies were included in the meta analysis regarding the increase in visual acuity after cataract surgery. The median increase in visual acuity was about 5 visual units (interquartile range 3.6 - 8.0 units) reaching a median postoperative visual acuity of 0.8. The median incidence rate of posterior capsule opacification during the observed period of 5 years was estimated 24 % (10 - 34 %). Computation of the current reimbursement rates of German health insurance resulted in a median incremental cost of 223.25 euro; per gained visual unit. CONCLUSION: Providing of cataract patients with monofocal intraocular lenses means median incremental costs of about 223 euro; to be refunded by the health insurance and is associated with a median visual acuity outcome of 0.8. Therefore the cost effectiveness of cataract surgery can be regarded quite encouraging compared to the outcome of other ophthalmological outpatient surgery.

Cataract↗
PubMed2002

[Implantation of an ARTISANtrade mark toric phakic intraocular lens to correct high astigmatism after penetrating keratoplasty].

BACKGROUND: Visual outcome after penetrating keratoplasty is often Iimited by residual astigmatism. Sometimes conservative treatment modalities like glasses or contact lenses fail to correct the keratoplasty-associated astigmatism. Refractive options are arcuate keratotomy, photorefractive keratectomy or laser in situ keratomileusis. The implantation of an ARTISAN toric intraocular lens presents an additive option to correct corneal astigmatism in phakic eyes. This toric intraocular lens (IOL) has an optical zone of 5.0 mm with a sphericaI front and a toric back. The torus of the IOL is available up to 7 D in half dioper steps. CASE REPORT: A 27-year old female presented with a bestcorrected visual acuity of 20/32. Penetrating keratoplasty was performed in 1997 because of a decompensated keratoconus. Despite a clear allgraft visual acuity was limited because of a keratoplasty-related high astigmatism of 7.6 D/124 degrees, which could not be sucessfully treated with glasses or contact lenses. An ARTISAN toric intraocular lens with - 3 D spherical and 7.0 D/0 degrees cylindrical power (individually manufactured) was implanted via a sclerocorneal tunnel incision into the anterior chamber. Postoperatively an optimal graft clarity with a well-centered and stable-positioned IOL was found. After 3 months uncorrected visual acuity was 20/25. Six months after implantation the IOL was still well-centered and uncorrected visual acuity was 20/20. CONCLUSION: Implantation of an ARTISAN toric intraocular lens in phakic eyes is an alternative and new option to correct higher astigmatism. In contrast to the keratorefractive option minor manipulation on the allograft can be expected. For a final conclusion of the endothelial cell loss longer follow-up is necessary.

Adult↗
PubMedDate not supplied

Material properties of various intraocular lenses in an experimental study.

INTRODUCTION: With the recent introduction of small-incision cataract surgery, requirements for intraocular lens (IOL) flexibility, strength and hydrophilicity have rapidly evolved. The IOL surface, however, remains a critical factor influencing uveal biocompatibility. PURPOSE: To objectively quantify factors of material properties of various IOLs using contact angle measurements, differential scanning calorimetry, dynamic-mechanical measurements and scanning electron microscopy. MATERIAL AND METHODS: In our study, 17 currently available IOLs were investigated using contact angle measurements to assess hydrophilicity and biocompatibility, as well as differential scanning calorimetry for the estimation of glass transition temperature. Mechanical capacity and flexibility were investigated using dynamic-mechanical measurements. Additional analysis of the IOL surface was performed using scanning electron microscopy. RESULTS: The contact angle measurements of the studied IOLs revealed similar values within each group. The silicone IOLs had values between 106 and 119 degrees. The PMMA IOLs were found to have a narrower range of values, between 73.2 and 75.5 degrees. Lenses made of hydrogel had values between 59.2 and 69.1 degrees. The heparin-modified surface showed the lowest contact angle of 56.5 degrees. The glass transition temperature was determined by dynamic differential scanning calorimetry. The resulting values were between 118.8 and 113.5 degrees C for PMMA IOLs, 15.5 and 14.0 degrees C for acrylic IOLs, and -91.7 and -119.6 degrees C for silicone IOLs. The dynamic-mechanical measurements revealed that PMMA lenses manifested characteristics similar to glass, whereas silicone lenses had characteristics similar to rubber. Acrylic lenses were between rubber and glass. Scanning electron microscopy revealed smooth dispersion of fibrin on hydrophobic IOLs and a relative lack of fibrin adhesion on hydrophilic materials. CONCLUSION: These results demonstrate that material properties of various IOL materials are consistent within classes of IOL materials. This suggests that the intraoperative and postoperative behavior of an IOL is predictable and related to its composition, thus allowing surgeons to choose IOLs more appropriate for different surgical situations and individual patient characteristics.

Acrylates↗
PubMedDate not supplied

Refractive lens exchange with an array multifocal intraocular lens.

PURPOSE: To prospectively evaluate safety, efficacy, predictability, stability, complications, and patient satisfaction after refractive lens exchange (clear lens extraction) followed by posterior chamber implantation of a multifocal intraocular lens (IOL). METHODS: Fifty eyes of 25 patients (mean age 51 years, range 44 to 62 years) with preoperative spherical equivalent refraction between -15.50 and +5.75 D and cylinder between 0 and 1.50 D underwent bilateral implantation of a zonal progressive multifocal IOL (Array, AMO). RESULTS: Eyes were divided into group A (n=24; myopia, average preoperative spherical equivalent refraction -7.11 +/- 3.25 D (-1.75 to -15.50 D), and group B (n=26; hyperopia, average preoperative spherical equivalent refraction +3.04 +/- 1.04 D). Follow-up was 6 months in all eyes. Postoperatively, all eyes of both groups were within +/-1.00 D of target refraction. No eye in group A and three eyes in group B sustained a loss of one line of BSCVA. Forty-seven eyes (94%) remained unchanged or gained one or more lines of their preoperative BSCVA. In all eyes, postoperative UCVA was 20/40 or better. When compared to preoperative, uncorrected near visual acuity improved (statistically significant). All patients achieved uncorrected binocular visual acuity of 20/30 and J4 or better. Patient satisfaction was extremely high; no intra- or postoperative complications were reported. CONCLUSION: Six-month results of implantation of the AMO Array multifocal IOL for refractive lens exchange demonstrated safety, efficacy, and predictability in correcting high ametropia and significant improvement of uncorrected near and distance visual acuity.

Adult↗
PubMedDate not supplied

The "sandwich technique" for iris-fixated phakic intraocular lens implantation.

PURPOSE: To describe a new technique of implantation of the Artisan/Verisyse phakic intraocular lens (PIOL). METHODS: After PIOL insertion into the anterior chamber, a bolus of a high viscosity ophthalmic viscosurgical device (OVD) is placed over the optic, separating it widely from the endothelium. RESULTS: The technique decreases the chance of endothelial damage during enclavation. CONCLUSIONS: A bolus of a high viscosity OVD placed on the anterior surface of the Artisan/Verisyse PIOL may make enclavation safer.

Anterior Chamber↗