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October 11, 2002
Elliptical LASEK may have edge for astigmatic patients
Eurotimes/october2002
NICE — A new variation of LASEK called excimer laser sub-epithelial ablation (ELSA) which uses elliptical instruments produces excellent outcomes in astigmatic patients.The ELSA instruments consist of an elliptical-shaped microtrephine (11.0 mm x 8.0 mm) with a 70 micron calibrated blade and an elliptical shaped alcohol cone (11.5 mm x 8.5 mm). The epithelial trephine has a blade on the corneal side that cuts 70 microns into the epithelium and Bowman’s layer. The blade is interrupted on one side of the longer axis, leaving a hinge of 2.0 mm.The ELSA instruments create a circular epithelial flap that exceeds the 8.0 mm maximum cut achieved by current methods. This approach to astigmatic correction using the excimer laser involves ablating tissue from the cornea in a cylindrical fashion. The toric ablation patterns are generally 9.0 mm to 10.0 mm long in one of the cylindrical axes.
Posted by mehdi khanlari at 05:50 PM
New thermodynamic IOL may provide a bag full of accommodation
Eurotimes/October2002
NICE — A new thermodynamic injectable IOL (SmartLensTM, Medennium) which mimics the properties of the natural crystalline lens may provide a new means of restoring accommodation to cataract patients and presbyope.The new IOL is reducible at room temperature to a rod 2.0 mm in diameter which can be inserted through a micro-incision. Once inside the eye, it will unfold to a diameter of 9.5 mm with an average thickness of 2.0 mm to 3.0 mm.
The bi-convex lens will fill the entire capsular bag and remain perfectly centred without the aid of haptics. The gel-like hydrophobic acrylic material of the lens is pliable and has a high refractive index. This means that small changes in the central thickness will result in large changes in accommodative amplitude.Moreover, prior to rod formation at room temperature, the thermodynamic hydrophobic acrylic polymer can have imprinted on it the exact dioptric power in whatever dimensions are desired. The lens can include customised surfaces based on wavefront aberrometry and once inside the eye it will re-conform to the initially imprinted configuration. The new lens, currently undergoing toxicity and optical bench studies, will be implantable through a standard capsulorhexis and remain stably positioned thereafter. And since the lens fills the entire capsule it may prevent the migration of lens epithelial cells which is the principle cause of capsular opacification.
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Posted by mehdi khanlari at 05:42 PM
October 09, 2002
Erbium glass laser shows promise in hyperopia
Eyeworld.oct02
A new noncontact erbium glass laser has yielded encouraging results in the treatment of hyperopia and hyperopic astigmatism, an ophthalmologist based in Hungary says. The principle is based on the retraction of the peripheral stroma, inducing a central curvature.In a study involving 450 eyes of 230 patients who underwent treatment for +0.75 to +6 D of hyperopia with or without astigmatism, all showed improvement of their uncorrected visual acuity and none lost more than 1 line of best-corrected visual acuity.The patients in the study included 134 women and 96 men with a mean age of 39.5 years, within a range of 19 to 60. The spherical equivalent was between +0.75 and +3 D in 90 eyes, between +3 and +6 D in 110 eyes, and greater than +6 D in 80 eyes. Patients underwent treatment with a noncontact erbium glass laser which has a wavelength of 1.54 µm, a spot size of 400 to 450 µm, and energy ranging from 190 to 320 mJ. Erdos applied 24 to 36 spots on two to three concentric rings with diameters of 6, 7, and 8 mm. She applied an additional four to six spots on the flattest meridian in astigmatic eyes. The erbium glass laser is an alternative to PRK [photorefractive keratectomy], LASIK [laser in-situ keratomileusis], and the holmium:YAG laser. Unlike excimer treatments, it does not require debridement of the cornea [no haze] or the use of microkeratome and the creation of a flap.Its potential range of applications includes the treatment of mild and moderate hyperopia, mild and moderate hyperopic astigmatism, and especially
Posted by mehdi khanlari at 10:54 PM
October 05, 2002
New advances in the surgical treatment of glaucoma
Eyeworld.october2002
A miniature glaucoma drainage device, the Ex-Press, provides intraocular pressure reduction in open-angle glaucoma patients, similar to a trabeculectomy. The device was developed by the Swiss-Israeli firm, Optonol Ltd., and in August, Ciba Vision acquired the rights to market it in the United States and Canada. The novel device diverts the aqueous humor from the anterior chamber to the subconjunctival space to form a filtering bleb.The Ex-Press is devised to replace conventional glaucoma surgery and is not to be used as a last-ditch surgery as the large glaucoma drainage devices are.Implantation is rapid, usually less than 5 minutes, he said. It involves minimal tissue manipulation, because it doesn’t require a large conjunctival flap, cautery, scleral dissection, or iridectomy,The insertion procedure is simple, less traumatic than conventional filtering surgery, and is reproducible.The 3-mm long, 400-µm diameter implant received Food and Drug Administration approval in May and is CE marked for marketing in Europe. The device has been implanted in more than 1,200 human patients since 1997 in worldwide clinical trials and is used commercially in Europe
Posted by mehdi khanlari at 11:38 PM
October 03, 2002
Corticosteroids and central serous chorioretinopathy
Ophthalmology (2002) 109: 1834-1837
To investigate the relationship between corticosteroid use and central serous chorioretinopathy (CSC). A consecutive series of patients with acute manifestations of CSC and a control group matched for age, race, and gender were recruited between January 2000 and July 2000. A total of 50 patients was recruited. Twenty-six patients (52%) had a history of exogenous steroid use, including oral, intravenous, intranasal, and intraarticular administration. Two additional patients had a history of endogenous hypercortisolism (Cushing’s syndrome). In a matched control group, eight patients (18%) had a history of steroid use. The difference in corticosteroid exposure between study patients and controls was statistically significant (P < 0.0001). This study is consistent with previous reports associating steroid use with CSC. It identifies corticosteroids as a significant risk factor for the development of acute, exudative macular manifestation and implicates hypercortisolism as a factor in the pathogenesis of this disorder. Several forms of corticosteroid administration were observed to be a risk factor for CSC. Accordingly, susceptible patients in need of corticosteroids should be advised of the risk of developing acute manifestations of CSC.
Posted by mehdi khanlari at 06:43 AM
Surgical strategies for coexisting glaucoma and cataract
Ophthalmology (2002) 109: 1902-1913
To assess short- and long-term control of intraocular pressure (IOP) with different surgical treatment strategies for coexisting cataract and glaucoma. We performed a search of the published literature to identify all eligible articles pertaining to the surgical management of coexisting cataract and glaucoma in adults. One investigator abstracted the content of each article onto a custom-designed form. A second investigator corroborated the findings. The evidence supporting different approaches was graded by consensus as good, fair, weak, or insufficient. The evidence was good that long-term IOP is lowered more by combined glaucoma and cataract operations than by cataract operations alone. On average, the IOP was 3 to 4 mmHg lower in the combined groups with fewer medications required. The evidence was weak that extracapsular cataract extraction (ECCE) alone results in short-term increase in IOP and was insufficient to determine the short-term impact of phacoemulsification cataract extraction (PECE) on IOP in glaucoma patients. The evidence was weak that short-term IOP control was better with ECCE or PECE combined with an incisional glaucoma procedure compared with ECCE or PECE alone. The evidence was also weak (but consistent) that long-term IOP is lowered by 2 to 4 mmHg after ECCE or PECE. Finally, there was weak evidence that combined PECE and trabeculectomy produces slightly worse long-term IOP control than trabeculectomy alone, and there was fair evidence that the same is true for ECCE combined with trabeculectomy. There is strong evidence for better long-term control of IOP with combined glaucoma and cataract operations compared with cataract surgery alone. For other issues regarding surgical treatment strategies for cataract and glaucoma, the available evidence is limited or conflicting.
Posted by mehdi khanlari at 06:21 AM
October 02, 2002
Corneal implants intended for insertion beneath the epithelium
OCULAR SURGERY NEWS 10/1/02
SYDNEY, Australia – A novel method of inserting a contact lens just below the epithelium is in animal clinical trials here, in an effort to provide an effective yet reversible method of vision correction. The corneal onlay is a contact lens designed to be inserted just beneath the epithelium to provide stable yet reversible refraction. Patients could potentially have less visual downtime than with LASIK and improved long-term stability of refractive correction, the device’s developers say. To insert the onlay, the epithelium is removed and the onlay placed on the underlying tissue. The epithelium then regrows, incorporating the inlay into the corneal tissue as part of the normal wound-healing response. The lens could be removed or replaced as the refractive needs of the patient changed with time. The lens could also be used to replace scarred or diseased corneal tissue. This would eliminate the problems of limited supply, tissue rejection and infection associated with corneal transplants. The onlay is made from a highly porous perfluoropolyether that is isorefractive with corneal tissue. The correction in refractive error is achieved by the change in curvature of the anterior corneal surface. The first-generation CRCERT Implantable Lens will offer a range of correction from –6 D to 6 D, with astigmatic and possibly presbyopic applications in the future.
The procedure is the simplest, easiest and most reversible of all potential refractive surgery procedures. It should be predictable and very optically accurate,“These amazing materials also have their surface topography designed so that the basal layer of the epithelium will invade the surface of the lenticle, synthesizing the attachment fibrils and plaques to anchor the epithelium. Perhaps even more important is that we have researched, defined and patented the permeability needed through the onlay to supply the epithelium with the aqueous-derived metabolites essential to its health. The polymer must be biocompatible with the surrounding tissue, as well as encourage and sustain a functioning epithelium to grow over the implant. The implant will maintain this compatibility for at least 10 years. If the patient requires their prescription to be updated, it would be a simple procedure to remove the implant and replace it. Currently the candidate polymer is being tested and could enter human trials in 2 or 3 years.
Posted by mehdi khanlari at 11:42 AM
October 01, 2002
Implants help manage aniridic patients
OCULAR SURGERY NEWS 9/15/02
Options for surgical management of patients with traumatic or congenital aniridia are few, but several implants now offer hope for patients with the condition. Though no implants currently have regulatory approval in the United States, one is now in clinical trials and others have been implanted on a compassionate-use basis.The Ophtec Aniridia Lens (Ophtec USA) recently began a clinical trial for Food and Drug Administration approval. The first implant in the trial was performed last month by Francis W. Price Jr., MD. According to the company, this is the first multicenter study of an implantable artificial iris for FDA approval. Sources agree the low incidence of patients suffering from such iris defects is a main reason device manufacturers have not previously sought FDA approvals.
Posted by mehdi khanlari at 06:26 AM