Volume 5, Number 50
Monday, December 19, 2005



In this issue: (click heading to view article)
Sensitive and Rapid PCR-Based Diagnosis of Mycotic Keratitis
Transconjunctival Suture Adjustment for Initial IOP Control After Trabeculectomy
Corneal Higher-Order Aberrations Induced by Myopic and Hyperopic LASIK
Briefly











Sensitive and Rapid PCR-Based Diagnosis of Mycotic Keratitis

India’s Central Drug Research Institute has developed a method for early and correct diagnosis of mycotic keratitis.

Corneal scrapings of four patients were processed for DNA extraction. They were amplified by fungal specific primers of internal transcribed spacer region I (ITS1). These products were sequenced and analyzed by single stranded conformation polymorphism (SSCP) for species identification. The DNA samples from all four corneal scrapings were successfully amplified by the primer pair ITS1 and ITS2, and investigators established similarity/dissimilarity using Jaccard"s coefficient. Patient Isolate 1 was identified as Nectria hematococca, Isolate 2 as Candida albicans, and Isolates 3 and 4 as Bipolaris papendorfii. This led to prompt initiation of antifungal therapy in all cases, and useful vision was restored.

The authors believe that this method allows for earlier correct diagnosis than conventional methods, and that it can help in the prompt initiation of antifungal therapy in patients suspected of having mycotic keratitis infection.

SOURCE: Kumar M, Mishra NK, Shukla PK. Sensitive and rapid polymerase chain reaction based diagnosis of mycotic keratitis through single stranded conformation polymorphism. Am J Ophthalmol. 2005;140(5):851-57. 		Table of Contents











Transconjunctival Suture Adjustment for Initial IOP Control After Trabeculectomy

In an experimental human eye model of trabeculectomy, scleral flap suture adjustment allows predictable control of intraocular pressure (IOP). This approach had not previously been described in clinical use; in this study, New Zealand investigators present a prospective, non-comparative, interventional case series with the application of the technique.

Surgeons performed 40 trabeculectomies using a 3 mm x 4 mm scleral flap with two apical adjustable 10-0 nylon sutures under a fornix-based conjunctival flap. Intraoperatively the scleral flap sutures were tied tightly to appose the edges of the flap. All trabeculectomies were augmented with antimetabolite intraoperatively. On Day 1, patients with an IOP greater than 15 mm Hg had their suture tension adjusted to lower their IOP to a target range (10 mm Hg to 15 mm Hg). Major outcome measures were IOP before and after adjustment and success at last follow-up (IOP 15 mm Hg or lower on no glaucoma medication and no clinically significant complications) without and with adjunctive needling. Other outcomes measured were postoperative complications, bleb needling, final bleb morphology and visual acuity change from pre-operation to final follow-up.

Average Day 1 IOP was 14.8 mm Hg (SD 7.8). Fourteen patients had a Day 1 IOP higher than 15 mm Hg and underwent suture adjustment, lowering IOP to between 10 mm Hg and 15 mm Hg. (Mean post adjustment IOP was 10.7 mm Hg [SD 3.6]). One patient had a conjunctival tear intraoperatively. Four patients had transient wound leaks. No patients had shallow anterior chambers. All but four had diffuse blebs at last follow-up. Success rate without any further surgical intervention was 75 percent, and success rate with adjunctive needling was 100 percent. The mean duration of follow-up was 6.3 months (range 1 to 12 months).

The authors conclude that tying scleral flap sutures tightly with transconjunctival adjustment of sutures if IOP is greater than 15 mm Hg on Day 1 allows excellent control of early postoperative IOP.

SOURCE: Ashraff NN, Wells AP. Transconjunctival suture adjustment for initial intraocular pressure control after trabeculectomy. J Glaucoma. 2005;14(6):435-40.		 Table of Contents










Corneal Higher-Order Aberrations Induced by Myopic and Hyperopic LASIK

Investigators at Germany’s Johann Wolfgang Goethe-University compared the change in anterior corneal higher-order (third- to fifth-order) aberrations induced by myopic and hyperopic LASIK in a retrospective, comparative case series.

A total of 100 eyes (50 myopes and 50 hyperopes) of 59 patients were included. The mean preoperative spherical equivalent (SE) was -4.22 +/- 1.78D (range, -1.25D to -8.00D) in the myopic group (Group 1) and +2.72 +/- 1.25D (range, +0.25D to +5.00D) in the hyperopic group (Group 2). Surgeons performed LASIK using a conventional spherocylindrical laser algorithm (Planoscan V2.9992, Bausch & Lomb/Technolas). Optical zone diameter was 6.70 +/- 0.32 mm (range, 6 mm to 7 mm) in Group 1 and 6.59 +/- 0.19 mm (range, 6.5 mm to 7 mm) in Group 2. Third- to fifth-order corneal higher-order aberrations were computed for a pupil diameter of 6 mm from corneal topographic examinations before and one month after surgery.

The total higher-order aberration root mean square (RMS) changed in Group 1 by 0.167 +/- 0.180 microns (factor 1.53) and in Group 2 by 0.341 +/- 0.341 microns (factor 1.89). The mean induction of coma RMS was significantly different in both groups (myopes, 0.092 +/- 0.195 microns; hyperopes, 0.252 +/- 0.305 microns). For spherical aberration (Z 4,0), the Group 1 showed a significant increase (0.130 +/- 0.120 microns; factor 1.6), whereas Group 2 showed a significant decrease (-0.317 +/- 0.158 microns; factor 0.76). Fifth-order aberrations showed an increase in both groups, which was higher in Group 2 (0.069 +/- 0.120 microns; factor 2.46) than in Group 1 (0.005 +/- 0.065 microns; factor 1.49).

The results show that myopic and hyperopic LASIK have different patterns of higher-order aberration induction. Myopic LASIK induced positive spherical aberrations and positive secondary astigmatism, whereas hyperopic LASIK induced negative spherical aberrations and negative secondary astigmatism. Hyperopic LASIK induced more third- and fifth-order comalike aberrations than myopic LASIK.

SOURCE: Kohnen T, Mahmoud K, Buhren J. Comparison of corneal higher-order aberrations induced by myopic and hyperopic LASIK. Ophthalmol. 2005;112(10):1692.		 Table of Contents

 




BRIEFLY
  • FDA DENIES APPROVAL OF INSPIRE"S DRY EYE DRUG. The FDA recently sent Inspire Pharmaceutical a second letter outlining steps it needs to take before the FDA will approve diquafosol tetrasodium, a P2Y2 receptor agonist targeted for treating dry eye disease through rehydration of the ocular surface. Inspire says that the FDA strongly encouraged representatives of the to meet with its agents to discuss how best to move forward with the application, and that it intends to request such a meeting. The company also plans to discuss strategies for the diquafosol tetrasodium program in a Joint Development Committee with its partner, Allergan. For more information, go to www.inspirepharm.com.
  • ANTIMICROBIAL SELENIUM-COATED CONTACT LENSES IN CLINICAL TESTS. Emergent Technologies Inc. (ETI) has announced that one of its companies, Selenium Ltd., has entered into an agreement with the Institute for Eye Research at the University of New South Wales, Sydney, NSW, Australia. The Institute will conduct laboratory and clinical testing of antimicrobial contact lenses using a proprietary selenium coating. Terms were not disclosed. The technology was developed by Drs. Ted Reid and Julian Spallholz at Texas Tech University Health Sciences Center in Lubbock, TX. More than 250 patients are expected to participate in the clinical trials, which will test daily-wear and extended-wear coated lenses. The objective is to demonstrate that lenses coated with selenium can stop the normal buildup of bacteria, film and deposits on the lenses, and that this will eliminate adverse reactions, risk of infection and discomfort. For more information go to www.seleniumltd.com.
  • UPDATED CLINICAL RESULTS AVAILABLE FOR SJÖGREN"S SYNDROME TREATMENT. Immunomedics has reported that patients with primary Sjögren"s Syndrome retained clinical benefits six months after being treated with epratuzumab. The trial was an open-label, non-randomized, two-center Phase I/II study aimed at assessing the feasibility, safety and early evidence of efficacy in fifteen patients with primary Sjögren’s Syndrome. Epratuzumab, a recombinant humanized antibody against CD22 expressed on B-lymphocytes, was administered intravenously in about one hour, every other week, for four doses of 360mg/m(2) each. Patients were then evaluated 24 hours, four weeks, 12 weeks and six months post-therapy. Epratuzumab therapy was associated with a mean decrease in circulating B-cells of 33 percent during the six-month evaluation. No immunogenicity was observed, and one patient experienced a serious drug-related infusion reaction, which resolved completely with no further recurrence of symptoms.


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