Volume 10, Number 13
Monday, April 5, 2010



In this issue: (click heading to view article)
Retinal Function in Glaucoma Patients Following Trabeculectomy
Impact of in Vivo Laser Confocal Microscopy in the Diagnosis of Meibomian Gland Dysfunction
Thickening of the Inner and Outer Retina and Visual Acuity in Patients with Epiretinal Membrane
The Relationship Between Corneal Biomechanics, Refraction and Corneal Aberrometry in Keratoconus
Briefly










Retinal Function in Glaucoma Patients Following Trabeculectomy

Investigators in Sweden examined retinal function after reduction of IOP by filtration surgery in patients with medically uncontrolled glaucoma. A total of 11 patients (11 eyes) with medically uncontrolled glaucoma underwent trabeculectomy in this interventional, prospective, consecutive case series.

The investigators performed clinical investigation, visual field (testing with standard automated perimetry [SAP-Humphrey]), optical coherence tomography (OCT), full-field electroretinopgraphy (full-field ERG) and multifocal electroretinography (mfERG) preoperatively as well as 2 and 6 months after surgery.

They saw no significant reduction in mean logMAR visual acuity 2 or 6 months after filtration surgery and the mean preoperative IOP of 27.1 (±6.2) mmHg decreased to 19.0 ((±6.1) mmHg 2 months after surgery and to 17.1 ((±3.4) mmHg 6 months after surgery (both p=0.001). The investigators noted that the reduction in IOP significantly decreased the number of anti-glaucoma agents used, from 3.7 (± 1.6 at baseline to 0.8 (± 0.9 2 months after surgery and to 1.3 (± 1.2 6 months after surgery (p=0.004 and p=0.008, respectively). The results of SAP, OCT and full-field ERG did not show any significant difference between pre- and postoperative values at any point in time. Additionally, the study investigators found no significant improvement with regard to the first positive peak (P1) amplitudes in the macular retina (area 1) or in the perimacular retina/periphery (area 2) when measured with mfERG 2 months after surgery. The mfERG examinations revealed significantly improved P1 amplitudes 6 months after surgery in both area 1 and area 2, compared with the preoperative values (p=0.042 and p=0.014, respectively). Furthermore, the investigators reported that the implicit time of P1 decreased significantly 6 months after surgery in area 2 compared with the preoperative values (p=0.023).

They concluded that a significant lowering of IOP seems to improve the function of the central retina, as demonstrated by increased amplitudes and reduced implicit times assessed with mfERG.

SOURCE: Wittström E, Schatz P, Lövestam-Adrian M, et al. Improved retinal function after trabeculectomy in glaucoma patients. Graefes Arch Clin Exp Ophthalmol 2010;248(4):485-495.





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Impact of in Vivo Laser Confocal Microscopy in the Diagnosis of Meibomian Gland Dysfunction

The authors of this Japanese prospective, controlled, single-center study evaluated the efficacy, sensitivity and specificity of confocal microscopy (CM) parameters: meibomian gland (MG) acinar longest diameter (MGALD), MG acinar shortest diameter (MGASD), inflammatory cell density (ICD) and MG acinar unit density (MGAUD) in the diagnosis of MG dysfunction (MGD).

They recruited 20 MGD patients (9 males, 11 females; mean age, 63.5(±16.5 years) and 26 age- and gender-matched control subjects (13 males, 13 females; mean age, 53.2(±15.7 years). All subjects underwent slit lamp examinations, tear film break-up time (BUT) measurements, assessment of tear evaporation rate from the ocular surface (TEROS), vital stainings, Schirmer test, meibography, MG expressibility and CM of the MG. The authors compared the data between the 2 groups using the Mann-Whitney and chi-square tests. As far as main outcome measures, the authors tested the correlation between the clinical findings of tear functions, vital staining scores and the 4 CM parameters by Spearman's correlation coefficient by rank test. Additionally, receiver operating characteristic curve technique was used to evaluate the sensitivity, specificity and cutoff values of CM parameters.

According to the study authors, the mean tear film BUT, vital staining scores, TEROS values, MG expressibility and MG dropout grades by meibography were significantly worse in MGD patients compared with controls (p<0.001). They noted that the mean values of the MGALD, MGASD, ICD and MGAUD in MGD patients were significantly worse than those observed in the controls with CM. All CM parameters showed a strong, significant correlation with tear functions, ocular surface vital stainings, MG expressibility and MG dropout grades. The cutoff value for MGALD, MGASD, ICD and MGAUD in the diagnosis of MGD were 65 µm, 25 µm, 300 cells/mm² and 70 glands/mm², respectively. Furthermore, the sensitivity and specificity values of these parameters under these cutoff values were 90% and 81% for MGALD, 86% and 96% for MGASD, 100% for ICD, 81% and 81% for MGAUD.

The authors determined that confocal microscopy has the potential to diagnose the simple MD with high sensitivity and specificity. The CM-based diagnostic parameters correlated significantly and strongly with the status of the ocular surface disease.


SOURCE: Ibrahim OM, Matsumoto Y, Dogru M, et al. The efficacy, sensitivity, and specificity of in vivo laser confocal microscopy in the diagnosis of meibomiam gland dysfunction. Ophthalmol 2010; 117(4):665-672.






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Thickening of the Inner and Outer Retina and Visual Acuity in Patients with Epiretinal Membrane

This study examined the relationship between thickening of the inner and outer retinal layers and visual acuity in patients with idiopathic epiretinal membrane.

A total of 30 eyes (30 patients) and 25 eyes of 25 healthy volunteers as age-matched normal control subjects were examined and the inner (between the vitreoretinal interface and the outer border of inner plexiform layer), outer and full retinal thickness at the fovea, parafovea and perifovea were measured using spectral-domain optical coherence tomography (SD-OCT).

It was noted that thickening ratios of both the inner and outer retina were greater in the fovea than in the other macular regions (p<0.0001) and that inner foveal retinal thickening was significantly greater than outer foveal retinal thickening (p<0.0001). However, outer retinal thickening in the fovea (r=0.644, p<0.001), parafovea (r=0.616, p<0.001) and perifovea (r=0.410, p=0.025) was significantly correlated with visual acuity; inner retinal thickening was not. It was also reported that visual acuity tended to be worse, although not significantly so, in eyes with photoreceptor disruption.

In conclusion, epiretinal membrane-induced retinal damage associated with visual acuity seems to be located within the outer retina external to the inner plexiform layer.

SOURCE: Arichika S, Hangai M, Yoshimura N. Correlation between thickening of the inner and outer retina and visual acuity in patients with epiretinal membrane. Retina 2010;30(3):503-508.




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The Relationship Between Corneal Biomechanics, Refraction and Corneal Aberrometry in Keratoconus

Spanish researchers evaluated the relationship of corneal biomechanical properties to refraction and corneal aberrometry in keratoconic eyes and found that the corneal resistance factor (CRF) correlates with the magnitude of corneal spherical-like aberrations, especially in severe keratoconus.

They included 81 consecutive keratoconic eyes of 81 patients ranging in age from 11 to 58 years in the study differentiated three groups according to the severity of keratoconus: mild (37 eyes), moderate (24 eyes) and severe (20 eyes). The researchers also evaluated visual acuity, refraction, corneal topography and corneal aberrations and analyzed corneal biomechanics in relation to two parameters: corneal hysteresis (CH) and CRF. They investigated correlations between these biomechanical factors and the remaining clinical parameters.

According to the study researchers, CH and CRF in the severe keratoconus group were significantly lower than those in the other two groups (p≤0.01). They found a significant difference in CRF between mild and moderate cases (p=0.04) and a moderate correlation between the CRF and mean keratometry in the overall sample (r=-0564). They also found a significant, strong correlation between the spherical-like root mean square (RMS) and the CRF only in the severe keratoconus group (r=-0.655). Moreover, multiple regression analysis revealed that CRF correlated significantly with keratometry and the corneal spherical-like RMS (R2=0.40, p<0.01).

Based on their findings, the researchers concluded that CRF should be considered an additional factor in keratoconus grading.

SOURCE: Piñero DP, Alio JL, Barraquer RI, et al. Corneal biomechanics, refraction and corneal aberrometry in keratoconus: an integrated study. Invest Ophthalmol Vis Sci 2010;51(4):1948-1955.












  • ALCON ACQUISITION OF DUREZOL AND ZYCLORIN COMPLETE.According to a recent press release, Alcon has received regulatory approval and has finalized the acquisition of the rights in the United States for the topical ophthalmic corticosteroid Durezol emulsion (used to treat postoperative inflammation and pain associated with ocular surgery) and the global rights, excluding Latin America, for the topical ophthalmic immunomodulator and immunosuppressive agent Zyclorin (under clinical investigation to treat dry eye and other ocular surface diseases) from Sirion Therapeutics, Inc. Alcon will immediately assume all marketing, promotion and sales of Durezol and according to management, it is continuing to evaluate options to acquire the antiviral Zirgan, which the FDA recently approved for the treatment of acute herpetic keratitis.
  • INTERNATIONAL ADVISORS APPOINTED TO AAO BOARD OF TRUSTEES. The International Advisor position on the American Academy of Ophthalmology's (AAO) Board of Trustees was established in 2010 to bring a global perspective to the board's decision making and policy setting. According to the AAO, each advisor serves a one-year term and represents one of the five major geographic world regions. Dennis S.C. Lam, MD, of Hong Kong and Stefan Seregard, MD, of Sweden, have recently been appointed to serve a one-year term on the Board. In 2011, the new appointees will represent two of the remaining three regsions.
  • FDA ACCEPTS LUX'S NDA FOR LUVENIQ. Lux Biosciences, Inc. has announced that the FDA has accepted the filing of the company's New Drug Application for Luveniq (oral voclosporin) and has granted the application priority review, which is given to drugs that offer major advances in treatment, or provide a treatment where no adequate therapy exists.
  • PROTOTYPE BIONIC EYE UNVEILED. Bionic Vision Australia (BVA) has unveiled its wide-view neurostimulator concept â€" a prototype bionic eye that will be implanted into Australia's first recipient of the technology. BVA says that the prototype will deliver improved quality of life for patients suffering from degenerative vision loss caused by retinitis pigmentosa and age-related macular degeneration. The implant, which consists of a miniature camera mounted on glasses that captures visual input, transforming it into electrical signals that directly stimulate surviving neurons in the retina, is currently undergoing testing. Says BVA, the device will enable recipients to perceive points of light in the visual field that the brain can then reconstruct into an image. For additional information, click here.
  • CLINICAL TRIAL FOR DIABETIC EYE DISEASE TREATMENT NOW ENROLLING PARTICIPANTS. The Juvenile Diabetes Research Foundation (JDRF) and The Wilmer Eye Institute of Johns Hopkins University announced that the Ranibizumab for Edema of the mAcula in Diabetes â€" Protocol 3 with High Dose Study (READ 3 Study) has begun enrolling participants and will evaluate the safety and efficacy of injections of an antibody treatment in people with diabetic macular edema (DME). The READ-3 Study is a collaboration between JDRF and Johns Hopkins University, with funding support from Genentech, Inc. and involves 14 clinical centers across the United States that will collectively enroll some 100 patients. The JDRF says that the study is designed to compare two different doses of the antibody treatment to determine if a higher dose is more effective in improving vision and decreasing retinal thickness; it will also determine whether higher doses can reduce the frequency of subsequent treatments for DME. Participants 18 years of age and older with confirmed DME (and no other factors that would exclude someone from the study) will receive either 1 or 2 doses of ranibizumab for six months, followed by a six-month follow-up period with the option for additional treatments. Learn more by clicking here. For additional study information and participation, visit www.READ3.net or JDRF's Clinical Trials Connection at http://www.trials.jdrf.org.
















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