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Biomedical subjects

M J Tassignon

Publications and source records attributed to M J Tassignon.

At least 19 recordsLinked to original sources
PubMed2005

Clinical, epidemiological and cost aspects of contact lens related infectious keratitis in Belgium: results of a seven-year retrospective study.

AIM: Evaluation of the clinical, epidemiological and cost aspects of contact lens related infectious corneal ulcers requiring hospitalisation. METHODS: A retrospective analysis was performed on the files of patients hospitalised for contact lens induced corneal ulcer in the eight Belgian University Hospitals over a seven-year period (January 1997 until December 2003). For all hospitalised patients registration of the diagnosis is compulsory using the International Code of Diagnostics (ICD-9). RESULTS: 107 patients with contact lens related corneal ulcer were included. The great majority, 99 subjects, used soft contact lenses, of which 9 were disposables, 73 planned replacement and 17 conventional lenses. Only 6 patients were night and day wearers. Three patients used daily disposable lenses. The most frequently cultured organisms were Pseudomonas and other Gram-negative germs (70%) and Acanthamoeba (16%). The majority (77%) of the corneal ulcerations were localised centrally which resulted in an average visual loss of 4 lines. In 16 patients a corneal graft was performed and one eye had to be eviscerated. CONCLUSION: Despite important technological improvements in contact lens materials and care systems, the problem of infectious ulceration has all but disappeared. On the contrary, during the study period, the number of patients hospitalised increased from 5 in 1997 to 22 in 2003, which is only partially explained by the increasing prevalence of lens wearers: 3,5% of the Belgian population in 1995 and 6,5% in 2003.

Acanthamoeba↗
PubMed2005

Gaussian broad-beam excimer laser: clinical and experimental results.

PURPOSE: To evaluate the mid-term (1-3 years) results of the Gaussian broad-beam excimer laser Delivery System (DS) after single treatment for the correction of myopia. To study the corneal surface with scanning electron microscopy (SEM) after excimer laser ablation using a flying spot delivery system (Bausch & Lomb) and a Gaussian Delivery System (GDS) (InPro). METHODS: The 1035 consecutive eyes studied were split in four groups with respect to the treated myopia, expressed in spherical equivalent: low myopia up to -3.00 D (183 eyes), moderate myopia from -3.25 D to -6.00 D (540 eyes), high myopia from -6.25 D to -10.00 D (210 eyes) and very high myopia from -10.25 D to -20.00 D (102 eyes). Four post-mortem eyes of two donors were treated using the flying spot DS on one eye and the GDS on the other eye. RESULTS: We achieved postoperative spheriqual equivalent within +/- 1 D of emmetropia in respectively 99.1%, 98.9%, 83% and 21% of the eyes of group 1, 2, 3 and 4. UCVA was 10/10 or better in respectively 65%, 51% and 19% of group 1, 2 and 3. UCVA was 5/10 or better in respectively 86% and 75% of group 3 and 4. The defocus equivalent refraction was 1.0 or less in respectively 98%, 93%, 62%, and 7% of the four groups. On SEM, the corneal surface presented a smooth and polished profile for the GDS. CONCLUSIONS: The Gaussian Delivery System gives comparable results to the flying spot laser system for surface laser ablation in myopic eyes up to -10 D. Advantages of this system are: smooth ablation surface, short treatment time, low haze rate, high reliability and easy maintenance of the device due to the optical DS. It is an interesting alternative for the more complex mechanical DS.

Follow-Up Studies↗
PubMed2005

Searching the way out for posterior capsule opacification.

Searching the way out for posterior capsule opacification was one of our goals in improving current cataract surgery techniques. The second goals was restoring accommodation but this goal prooved to remain unsolved. The bag-in-the-lens concept of IOL and implantation technique has been used in 271 patients of which 15 children. These patients have a follow-up of one month to 5 years. The optical axis of all these patients remained crystal clear, which allows us to conclude that the problem of PCO is solved by the bag-in-the-lens implantation concept. These very encouraging results inspired us to new ideas, which will receive priority in our research: accommodation and optimising the quality of vision by compensating for the ocular aberrations.

Cataract↗
PubMed2004

LASIK and arcuate incisions for the treatment of post-penetrating keratoplasty anisometropia and/or astigmatism.

PURPOSE: To study the efficacy of Laser In Situ Keratomileusis (LASIK) and Arcuate Keratotomy (AK) for the treatment of anisometropia and/or astigmatism after Penetrating Keratoplasty (PKP) in an attempt to optimize binocular vision. MATERIAL AND METHODS: Correction of post-PKP anisometropia and/or astigmatism was considered only when stable refraction was achieved for at least 6 months. Four eyes were treated for anisometropia and astigmatism using the LASIK technique (IN-PRO Gauss Excimer Laser and SKBM Microkeratome). Five eyes were treated with AK to correct post-PKP astigmatism only. The results were evaluated using the following parameters: uncorrected visual acuity (UCVA), best subjective spectacle correction (BSC-VA), corneal uniformity (CU) index and predictive corneal (PC) acuity from the Holladay Diagnostic Summary (HDS) analysis. RESULTS: Post-PKP anisometropia and astigmatism were treated successfully after primary LASIK in three out of the four cases. One eye needed an additional diode thermal keratoplasty (DTK). Astigmatism post-PKP was treated successfully after primary AK in four of the five cases. One eye needed an additional LASIK. CONCLUSION: AK can be used successfully in cases of low-grade post-PKP astigmatism. LASIK gives better results in cases of post-PKP anisometropia and astigmatism. In order to affine the final results a combination with other refractive techniques such as DTK can be proposed. CU index and PC acuity (EyeSys-HDS analysis) are poor predictive parameters for visual outcome in cases of irregular corneal surfaces as it is often the case after PKP.

Adult↗
PubMed2004

Intraocular lens exchange for late-onset opacification.

PURPOSE: To report on the clinical, light microscopic and spectroscopic analyses of Hydroview intraocular lenses (IOLs) explanted for late postoperative IOL opacification. MATERIAL AND METHODS: Retrospective study of all cases with secondary lens implantation performed at the University Hospital of Antwerp during a period of one year (2002-2003) for postoperative opacification of Hydroview IOLs. Further analyses on some of the explanted IOLs included gross and light microscopic evaluation and RAMAN spectroscopy. RESULTS: Lens exchange for late-onset IOL opacification was needed in seven eyes of six patients. IOL opacification became apparent between 15 and 25 months after uneventful phacoemulsification and lens implantation. Visual acuity varied from < 0.05 to 0.6 before explantation. In almost all cases postoperative visual acuity improved to the pre-opacification level. Light microscopic and spectroscopic analyses showed that the opacification was mainly located in the anterior portion of the IOL optic as a layer of irregular granular deposits composed of calcium phosphate. CONCLUSION: Late postoperative opacification of Hydroview IOLs may cause severe visual impairment, requiring explantation. Calcium phosphate is involved in the formation of these opacifications. Reporting on this type of complications is mandatory according to the Belgian and European directives for medical devices.

Aged↗
PubMed2003

Lasek for myopia: first results.

PURPOSE: To evaluate the efficacy and safety of laser-assisted subepithelial keratectomy (LASEK) for the treatment of myopia and astigmatism (low, moderate and high). MATERIAL AND METHODS: Laser-assisted subepithelial keratectomy was performed by 3 surgeons in 45 eyes using an INPRO Gauss Excimer laser (31 eyes) or a NIDEK EC-5000 Excimer Laser (14 eyes). The mean follow-up is 9 months (3-15 months). Preoperative best-corrected visual acuity (BCVA) and corneal topography were measured. The postoperative parameters were: uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalent refraction (SER), defocus equivalent refraction (DER), and corneal topography. RESULTS: The mean preoperative sphere and cylinder were -4.09 diopters (D) +/- 1.94 D (range -1.25 D to -9.75 D) and -0.67 D +/- 0.55 D (range 0 D to -2.50 D) respectively. No eye lost 2 or more lines of BCVA. The UCVA was > or = to 20/20 in 56% of the cases and 20/40 or better in 100% of the cases. No eye developed corneal haze that affected visual acuity. No major complications were recorded. CONCLUSIONS: LASEK treatment is a safe and effective technique for treatment of low to high myopia. This surgical technique is less invasive and more effective than LASIK because of the lack of flap- and microkeratome-related complications.

Adult↗
PubMed2002

[PRK with InPro-Gauss excimer laser: statistical analysis of results].

PURPOSE: To analyse retrospectively the pre- and postoperative refraction and visual acuity according to Standard Graphs proposed by Waring for refractive surgery. METHODS: Ninety-three eyes with myopia ranging from -1.50 to -8 diopters (D) and/or with astigmatism ranging from 0.75 to 3 D were treated between July 1998 and June 2001. The laser delivers a broad beam with a regular gaussian energy repartition obtained by means of a plate containing an array of diffractive micro-lenses. RESULTS: The coefficient of linear correlation between the attempted and achieved spherical equivalent refraction was 0.97. A postoperative spherical equivalent refraction between -0.50 and +0.50 D was found in 92.3% of eyes. The defocus equivalent refraction (spherical refraction added to one-half of the cylindrical component, ignoring the sign) represents more accurately the reality of the refractive state, and in our study was within +/- 0.50 D for 86.4% of the eyes. A preoperative best corrected visual acuity of 10/10 was found in 78% of eyes and 64% achieved postoperatively an uncorrected visual acuity of 10/10. CONCLUSION: The InPro-Gauss excimer laser gives good refractive results. The Gauss profile delivery system provides reliability and quality of the ablated surface of cornea.

Humans↗
PubMed2001

The effect of photodynamic therapy with bacteriochlorin a on lens epithelial cells in a capsular bag model.

Photodynamic therapy (PDT) with bacteriochlorin a(BCA) has proved to be a successful treatment for many cancers and to be cytocidal for different cell lines in culture. The present study aimed to investigate in vitro the potential of this treatment for killing lens epithelial cells (LECs) left in the human capsular bag after extracapsular cataract extraction (ECCE). Capsular bags were prepared from donor eyes using an ECCE procedure and incubated in various concentrations of bacteriochlorin a(1.6-50 microg ml(-1)) during various incubation periods (2-10 min). Subsequently, the capsules were illuminated during various exposure times (2-15 min) with a diode laser (wavelength 760 nm). After treatment, the capsular bags were cultured for 7 days in Eagle's minimal essential medium supplemented with 2% fetal calf serum. The specimens were fixed in glutaraldehyde/paraformaldehyde and examined with routine light microscopy, Hoechst staining for DNA and transmission electron microscopy. Proliferation of LECs on the posterior capsule was assessed in flat mounts. Capsular bags receiving BCA without illumination and capsular bags receiving illumination only served as controls.BCA alone or light alone have no effect on structure and proliferative activity of LECs. At a threshold protocol of incubation in BCA at 10 microg ml(-1)for 10 min and subsequent illumination for 15 min, proliferative activity of cells is largely arrested and nearly all LECs on the capsule exhibit severe signs of apoptosis. Photodynamic therapy with bacteriochlorin a induces cell death and suppression of proliferation inlens epithelial cells and could be a promising means of prevention of posterior capsule opacification.

Adult↗
PubMed2001

Eligibility criteria for Nd-YAG laser treatment of highly symptomatic vitreous floaters.

Ten eyes of nine patients were treated for very disturbing vitreous floaters with the technique of Nd-YAG laser vitreolysis. The Scanning Laser Ophthalmoscope (SLO) was used to objectivate the position, the size and the motility of the vitreous floaters with respect to the patient's visual axis, which can be precisely located with the SLO. With this technique it was possible to define more precisely some eligibility criteria for Nd-YAG laser treatment of vitreous floaters and to classify the vitreous floaters in ill-suspended and well-suspended floaters in the vitreous body, the well-suspended floaters responding better to treatment compared to the ill-suspended vitreous floaters. The treatment was performed using the Q-Switched Nd-YAG Laser type Nanolas 15S of Alcon.

Eligibility Determination↗
PubMed2001

[Comparison of preoperative target ametropia and postoperative refraction for three types of lenses and intra-ocular differences (one pliable acrylic, one pliable PMMA-copolymer and one non-pliable PMMA) ].

In this retrospective study we compared the preoperative target ametropia, calculated with the SRK-T formula, with the postoperative refraction after extracapsular extraction by phacoemulsification and implantation of different posterior chamber lenses. The results show, for all 3 types of lenses, a postoperative refraction stability after the first month. According to our criteria, after 6 month, we have respectively for the non foldable PMMA lens, the PMMA-copolymere foldable and the acrylic foldable lens: 78%, 72% and 78% of good results; 13%, 28% and 9% of mild results and 9%, 0% and 13% of bad results. According to our criteria, the acrylic foldable lens has a tendency to move slightly backwards and the foldable PMMA-copolymere lens to move slightly frontwards. The non foldable lens gives pretty good results, however it is difficult to compare this lens with the 2 other lenses because of the large size of the incision.

Cataract↗
PubMed2001

Combined fourth and sixth cranial nerve palsy after lumbar puncture: a rare complication. A case report.

Palsies of cranial nerves are well-known complications after lumbar puncture. Sixth nerve palsies are the most common. They normally occur 4 to 14 days after the lumbar puncture and spontaneously recover in a few weeks or months. The occurrence of a fourth nerve palsy following lumbar puncture however is extremely rare. We report on a patient who developed a combined contralateral fourth and sixth nerve palsy after lumbar puncture (Syndrome of Intracranial Hypotension), requiring surgical correction for secondary diplopia.

Abducens Nerve Diseases↗
PubMed2000

Multicenter study of the Artisan phakic intraocular lens.

PURPOSE: To assess the Artisan intraocular lens to correct myopia in phakic eyes. SETTING: European multicenter study sponsored by Ophtec BV, Groningen, The Netherlands. METHODS: In this prospective multicenter clinical study, the Artisan lens was implanted in 518 eyes between September 1991 and October 1999. The power of the lenses ranged from -5.0 to -20.0 diopters (D). Follow-up examinations were performed at 6 months and 1, 2, and 3 years. Follow-up ranged from 6 months (n = 454) to 3 years (n = 249). The preoperative uncorrected visual acuity (UCVA) was not recorded but was estimated to be worse than 0.1. The preoperative mean best spectacle-corrected visual acuity (BSCVA) was 0.67 +/- 0.26 (SD). Endothelial cell counts were done at 6 months and 1, 2, and 3 years in a subgroup of 129 eyes. RESULTS: A UCVA of 20/40 or better was observed in 76.8% of eyes regardless of the postoperative goal. A BSCVA of 20/40 or better was observed in 93.9% of eyes and remained stable throughout the follow-up. Of the eyes with extremely high myopia (>-15.0 D), 63.3% gained 2 or more lines of BSCVA; of those with moderate myopia (-5.0 to -10.0 D), 23.5% gained 2 or more lines. The mean endothelial cell density change was 4.8% at 6 months, 2.4% at 1 year, 1.7% at 2 years, and 0.7% at 3 years. The incidence of persistent adverse events at 3 years was relatively low. Secondary surgical interventions included repositioning of the lens because of poor initial placement and lens exchange because of preoperative power calculation errors. Glare and halo effects during night driving were noted and were related to large pupils in young patients. CONCLUSION: The Artisan lens is a safe, stable, efficacious, and predictable method to correct -5.0 to -20.0 D of myopia. This study suggests that the corneal endothelial cell loss is stabilized to the physiologically normal level after 3 years.

Adolescent↗
PubMed2000

Frontalis suspension combined with blepharoplasty as an effective treatment for blepharospasm associated with apraxia of eyelid opening.

PURPOSE: Essential blepharospasm can be associated with apraxia of eyelid opening and is characterized by the inability to initiate the act of eyelid elevation even after cessation of orbicularis spasms. Current therapies such as botulinum toxin injections, orbicularis resection, or neurectomy may be unsuccessful or have undesired side effects. METHODS: Frontalis suspension was used to treat 13 consecutive patients with apraxia and blepharospasm during a 4-year interval. Follow-up ranged from 16 months to 55 months. To improve the aesthetic outcome, an upper blepharoplasty was done at the same time as the frontalis suspension in 7 cases. RESULTS: Good or excellent functional results were obtained in 10 of 13 patients. In 6 of these patients, the spasm disappeared completely. Therapy was unsuccessful in 1 patient, and in 2 patients blepharospasm recurred after 9 months. CONCLUSION: Patients with blepharospasm and apraxia of eyelid opening may benefit from a frontalis suspension operation, which can be considered minimally invasive and reversible.

Adult↗
PubMed2000

Quantitative measurement of the PCCC area in the postoperative period.

BACKGROUND/AIMS: The major complication of extracapsular cataract extraction (ECCE) is posterior capsule opacification (PCO). Posterior continuous circular capsulorhexis (PCCC) seems to be very promising in preventing PCO. This study was aimed at determining if the PCCC area changes as a function of time and if pearl formation could influence it. METHODS: 24 eyes of 23 patients underwent ECCE with PCCC. Retroillumination photographs were taken at 6 months and then yearly. To measure the PCCC area, the computerised program EPCO (evaluation of posterior capsule opacification) was used. The ratio of the PCCC area in relation to the IOL surface was calculated for the different time stages and the presence of pearl formation was noted. Firstly, proportional changes in diameter were compared in PCCC areas measured after 6 months and after 1 year (group I, n=13) and after 1 year and 2 years (group II, n=14). Secondly, PCCC areas were compared between two time stages in patients with (group III, n=19) and without pearl formation (group IV, n=8). RESULTS: No statistically significant difference was found in diameter change in either group. The PCCC area remains stabile between 6 months to 1 year and 1 year to 2 years. No differences are found between eyes with or without pearl formation. CONCLUSIONS: The PCCC area remains stable as a function of time and is not influenced by pearl formation.

Adult↗
PubMed2000

Spontaneous corneal perforation and endophthalmitis in Pseudomonas aeruginosa infection in a ventilated patient: a case report.

We report a case of Pseudomonas keratitis and endophthalmitis after inoculation from the respiratory tract in a mechanically ventilated patient. In these (semi)comatose and more vulnerable patients, colonisation of the upper respiratory tract by Pseudomonas occurs frequently, and this can lead to inoculation of the eyes. Emphasis lies on careful prevention of ocular inoculation and aggressive therapy as soon as keratitis is noticed.

Corneal Ulcer↗
PubMed2000

Multifocal intraocular lens implantation in patients with presenile unilateral primary and secondary cataract.

Multifocal intraocular lens implantation was studied in 6 eyes with a unilateral cataract due to ocular trauma. Two patients had an uncomplicated traumatic cataract, two patients had a complicated traumatic cataract and two patients had a unilateral primary presenile cataract. Postoperative visual acuity for distance and for near vision, with and without additional spectacle correction, as well as the presence of postoperative binocular vision was evaluated. Additionally, we looked for pre- and postoperative parameters, assuming these criteria determine the success ratio of a multifocal intraocular lens implantation: presence of a stereoscopic vision pre-operatively, or absence of a pre-operative strabismus; rather good visual prognosis (no retinal damage in the traumatic cases and no amblyopia in the primary cases); normal functioning of the pupillary sphincter.

Adolescent↗
PubMed2000

Cell biological mechanisms underlying posterior capsule opacification: search for a therapy.

The present paper overviews our recent studies for PCO prevention using an in vitro human capsular bag model and application of hyperthermia and photodynamic therapy with Bacteriochlorin A as the sensitizer as described in previous papers. These studies clearly showed that both treatments are successful in vitro and almost completely reduce the proliferation of lens epithelial cells on the posterior capsule and thus are potential candidates to eliminate the occurrence of PCO in vivo. Hyperthermia has a threshold temperature between 55 degrees C and 60 degrees C which makes this approach not very useful for in vivo application. Threshold conditions for PDT/BCA are much more moderate. Recent preliminary in vivo studies in the rabbit showed that using the in vitro threshold conditions, the formation of a ring of Soemmering and outgrowth of lens epithelial cells on the posterior capsule is significantly reduced. However, these conditions have an adverse affect on the corneal stroma and endothelium. Studies of PDT conditions which further reduce LEC outgrowth without affecting the corneal integrity are in progress.

Animals↗